A novel Eu^(2+)-Eu^(3+)co-activated ratiometric thermo-sensitive phosphor was developed and synthesized by solid-state reaction.The valence state of Eu,photoluminescence and thermo-sensitive performance of the phospho...A novel Eu^(2+)-Eu^(3+)co-activated ratiometric thermo-sensitive phosphor was developed and synthesized by solid-state reaction.The valence state of Eu,photoluminescence and thermo-sensitive performance of the phosphor prepared either in ambient air or carbothermally were investigated and discussed.The phosphor shows high sensitivity(Sa=0.0173 K^(-1),S_(r)=0.461%/K)and superior signal discriminability(Δν∼10380 cm^(−1)).The thermo-sensitive performance is subject to the dual effects of different thermo-responses by Eu^(2+)versus Eu^(3+)combined with energy transfer from Eu^(2+)to Eu^(3+),so that the sensitivity of the phosphor in the temperature range presents a non-monotonic trend.The development of the BaAl_(2)B_(2)O_(7):Eu^(2+),Eu^(3+)phosphor is not only expected to be relevant for application in the field of temperature sensing,but also of reference significance for improving the sensitivity by means of energy transfer between co-activator ions over a wider temperature range of Eu^(2+)-Eu^(3+)co-activated ratiometric thermo-sensitive phosphors.展开更多
Efficient reconstruction of severe cutaneous wounds necessitates the orchestration of effective cell-mediated matrix remodeling and robust protection against microbial invasion.Herein,we engineered a near-infrared lig...Efficient reconstruction of severe cutaneous wounds necessitates the orchestration of effective cell-mediated matrix remodeling and robust protection against microbial invasion.Herein,we engineered a near-infrared light(NIR)-stimulated,thermo-responsive bilayer system based on a drug-loaded hydrogel with a thermal-responsive temperature of~42℃ as the matrix layer and an antibacterial nanofibrous mat as the top layer.The matrix layer integrates basic fibroblast growth factor(bFGF)-loaded thermosensitive gelatin(Gel)hydrogel with polydopamine-Cu^(2+)coated short nanofibers(P@SF).Upon NIR exposure,P@SF elicits a photothermal effect,causing a rapid increase in temperature by 13.4℃ within 1 min at a power density of 0.75 W/cm^(2),which triggers the gel-sol transition of Gel and controls the release of bFGF.This,in turn,enhances fibroblast and endothelial cells ingrowth into the hydrogel,fostering cell functionalization and matrix remodeling.The top layer consists of poly(L-lactide-co-caprolactone)nanofibers functionalized with lysine-doped polydopamine and poly-l-lysine.It possesses antibacterial efficacy by isolating,controlling(76.23%for E.coli and 89.16%for S.aureus),and eliminating bacteria upon NIR activation.In rat skin wound models,this NIR-responsive smart bilayer system prevents S.aureus-mediated bacterial infection(indicative of reduced IL-6 expression),regulates CD31-positive neovascularization,and facilitates collagen remodeling for skin regeneration.In summary,this study introduces a novel strategy,inspired by the centralization of authority,for developing a smart thermo-responsive system with promising potential for the effective reconstruction of severe cutaneous wounds.展开更多
The effect of graft yield on both the thermo-responsive hydraulicpermeability and the therrno-responsive diffusional permeability through porous membranes withplasma-grafted poly(N-isopropylacrylamide) (PNIPAM) gates ...The effect of graft yield on both the thermo-responsive hydraulicpermeability and the therrno-responsive diffusional permeability through porous membranes withplasma-grafted poly(N-isopropylacrylamide) (PNIPAM) gates was investigated. Both thermo-responsiveflat membranes and core-shell microcapsule membranes with a wide range of graft yield of PNIPAM wereprepared using a plasma-graft pore-filling polymerization method. The grafted PNIPAM was formedhomogeneously throughout the entire thickness of both the flat polyethylene membranes and themicrocapsule polyamide membranes. Both the hydraulic permeability and the diffusional permeabilitywere heavily dependent on the PNIPAM graft yield. With increasing the graft yield, the hydraulicpermeability (water flux) decreases rapidly at 25℃ because of the decrease of the pore size;however, the water flux at 40℃ increases firstly to a peak because of the increase ofhydrophobicity of the pore surface, and then decreases and finally tends to zero because of the poresize becoming smaller and smaller. For the diffusional permeability, the temperature showsdifferent effects on the diffusional permeability coefficients of solutes across the membranes. Whenthe graft yield was low, the diffusional coefficient of solute across the membrane was higher attemperature above the lower critical solution temperature (LCST) than that below the LCST; however,when the graft yield was high, the diffusional coefficient was lower at temperature above the LCSTthan that below the LCST. It is very important to choose or design a proper graft yield of PNIPAMfor obtaining a desired thermo-responsive 'on/off' hydraulic or diffusional permeability.展开更多
Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide （NIPAM） with silane-modified halloysite nanot...Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide （NIPAM） with silane-modified halloysite nanotubes （HNT） through thermally initiated free-radical polymerization. With methylene blue as a model drug, thermo-responsive drug release results demonstrate that the drug release from the nanotubes in the composited hy-drogel can^be well controlled by manipulating the environmental temperature. When the hydrogel network is swol- len at temperature below the lower critical solution temperature （LCST）, drug releases steadily from lumens of the embedded nanotubes, whereas the drug release stops when hydrogel shrinks at temperature above the LCST. The release of model drug from the HNT-composited hydrogel matches well with its thermo-responsive volume phasetransition, and shows characteristics of well controlled release. The design strategy and release results of the pro- posed novel HNT-composited thermo-responsive hydrogel system provide valuable guidance for designing respon- s_i_ve nanocomposites for controlled-release of active agents.展开更多
A novel hydrophilic nanocomposite additive （TiO2-g-PNIPAAm） was synthesized by the surface modification of titanium dioxide （TiO2） with N-isopropylacrylamide （NIPAAm） via ＂graft-from＂ technique. And the nanoco...A novel hydrophilic nanocomposite additive （TiO2-g-PNIPAAm） was synthesized by the surface modification of titanium dioxide （TiO2） with N-isopropylacrylamide （NIPAAm） via ＂graft-from＂ technique. And the nanocomposite membrane of poly（vinylidene fluoride） （PVDF）/TiO2-g-PNIPAAm was fabricated by wet phase inversion. The graft degree was obtained by thermo-gravimetric analysis （TGA）. Fourier transform infrared attenuated reflection spectroscopy （FTIR-ATR） and X-ray photoelectronic spectroscopy （XPS） characterization results suggested that TiO2-g-PNIPAAm nanoparticles segregated on membrane surface during the phase separation process. Scanning electron microscopy （SEM） was conducted to investigate the surface and cross-section of the modified membranes. The water contact angle measurements confirmed that TiO2-g-PNIPAAm nanoparticles endowed PVDF membranes better hydrophlilicity and thermo-responsive properties compared with those of the pristine PVDF membrane. The water contact angle decreased from 92.8~ of the PVDF membrane to 61.2~ of the nanocompostie membrane. Bovine serum albumin （BSA） static and dynamic adsorption experiments suggested that excellent antifouling properties of membranes was acquired after adding TiO2-g- PNIPAAm. The maximum BSA adsorption at 40℃ was about 3 times than that at 23 ℃. The permeation experiments indicated the water flux recover ratio and BSA rejection ratio were improved at different temperatures.展开更多
Despite the fact that some progress has been made in the self-assembly of H-shaped polymers, the corresponding self-assemblies that respond to external stimulus and are further utilized to adjust the release of drugs ...Despite the fact that some progress has been made in the self-assembly of H-shaped polymers, the corresponding self-assemblies that respond to external stimulus and are further utilized to adjust the release of drugs are still deficient. The stimuli-responsive segments with amphiphilic H-shaped structure are generally expected to enhance the controllability of self-assembly process. The synthesis and self-assembly behavior of thermo-responsive amphiphilic H-shaped polymers with poly（ethylene glycol） （PEG）, polytetrahydrofuran （PTHF） and poly（N-isopropyl acrylamide） （PNIPAM） as building blocks are reported in this paper. The inner architecture structure and size of complex micelles formed by H-shaped self-assemblies were effectively adjusted when the solution temperature was increased above the lower critical solution temperature of PNIPAM segments. Furthermore, it was found that the architecture of self-assemblies underwent a transition from the complex micelles based on primary micelles with hybrid PEG/PNIPAM shells to large complex micelles based on primary micelles with hybrid PTHF/PNIPAM cores and PEG shells during the thermal-induced self-assembly process. The adjustable release rate ofdoxorubicin （DOX） from the DOX-loaded complex micelles and basic cell experiments further proved the feasibility of these self-assemblies as the thermal-responsive drug delivery system.展开更多
Thermo-responsive butyl acrylate/furfuryl methacrylate copolymer-based （PBF backbone） graft （co）polymers with dynamic covalent linkages between their backbones and side chains via the Diels-Alder reaction of furar...Thermo-responsive butyl acrylate/furfuryl methacrylate copolymer-based （PBF backbone） graft （co）polymers with dynamic covalent linkages between their backbones and side chains via the Diels-Alder reaction of furardmaleimide were synthesized. Atom transfer radical polymerization （ATRP） was used to synthesize graft copolymers with thermo-responsive transformation from graft copolymers to linear polymers with bimodal or wide MWD. The NMR measurements indicated that the Diels-Alder reaction and retro- Diels-Alder reaction occurred, depending on the change of the temperature, meaning that the side chains could be cleaved and reformed according to the variation of the temperature. GPC measurements demonstrated that the molecular weights of the polymers were thermo- responsive. Furthermore, three graft copolymers with various branching chains （PBF-g-PBA, PBF-g-P（BMA-co-MA） and PBF-g-PBMA） were compared to study the influence of compatibility between the backbone and the branching chain on the efficiency of Diels-Alder reaction after the cleavage of the DA linkage. The results showed that the ability of the side chains to come back to the main chain was strongly affected by the compatibility between the backbone and the side chains and the flexibility of the polymer chains.展开更多
Therrno-responsive block copolymers poly（ethylene glycol）-block-poly（N-acryloyl-2,2-dimethyl-1,3-oxazolidine）, PEG-b-PADMO, based on linear PEG were prepared via a versatile reversible addition-fragmentation chain...Therrno-responsive block copolymers poly（ethylene glycol）-block-poly（N-acryloyl-2,2-dimethyl-1,3-oxazolidine）, PEG-b-PADMO, based on linear PEG were prepared via a versatile reversible addition-fragmentation chain transfer （RAFT） polymerization, PEG22 （Mw = 1000） was used as the hydrophilic component, whose dehydration was the main driving force for the phase transition of these copolymers, as demonstrated by the tH-NMR spectra. Their lower critical solution temperatures （LCSTs） could be tuned in the range of 20℃ to 35℃, by adjusting the degree of polymerization （DP） of PADMO between 14-27. Furthermore, a sharp phase transition at ca. 33℃, close to the physiological temperature with minimal hysteresis, was observed for the PEGzz-b-PADMO14 copolymer. Moreover, excellent reversibility and reproducibility were displayed for the same copolymer over 10 cycles of repeated temperature change between 25℃ （below the LCST） and 40℃ （above the LCST）.展开更多
In this work,the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature(LCST)of the macroporous thermo-responsive poly(N-isopropylacrylamide)grafted poly(viny...In this work,the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature(LCST)of the macroporous thermo-responsive poly(N-isopropylacrylamide)grafted poly(vinyl alcohol)formaldehyde(PVF-g-PNIPAM)hydrogels are investigated with differential scanning calorimetry(DSC).Four kinds of anions with strong hydration,including CO3^2–,SO4^2–,S2 O3^2–,and F^–,and four kinds of anions with weak hydration,including Br^–,NO3^–,I^–,and ClO4^–,and Cl^–as a medium anion are systematically studied and found to demonstrate the effects of the residual hydroxyl groups and network structure of PVF on the LCST values of PVF-g-PNIPAM hydrogels in comparison with that of neat PNIPAM.On the one hand,the existence of hydroxyl groups on PVF backbone promotes the solubility of grafted PNIPAM due to their hydrophilicity and hydrogen-bond interactions with water.On the other hand,the network structure of as-prepared samples restricts free movements of grafted PNIPAM chains,which results in the increase of LCST values.In addition,the difference of grafting percentage also influences the variation of LCST values of PVF-g-PNIPAM hydrogels under salt concentration.展开更多
The doubly thermo-responsive triblock copolymer nanoparticles of polystyrene-block-poly（N- isopropylacrylamide）-block-poly[N,N-（dimethylamino） ethyl methacrylate] （PS-b-PNIPAM-b-PDMAEMA） are successfully prepare...The doubly thermo-responsive triblock copolymer nanoparticles of polystyrene-block-poly（N- isopropylacrylamide）-block-poly[N,N-（dimethylamino） ethyl methacrylate] （PS-b-PNIPAM-b-PDMAEMA） are successfully prepared through the seeded RAFT polymerization in situ by using the PS-b-PNIPAM-TTC diblock copolymer nanoparticles as the seed. The seeded RAFT polymerization undergoes a pseudo-first-order kinetics procedure, and the molecular weight increases with the monomer conversion linearly. The hydrodynamic diameter （Dh） of the triblock copolymer nanoparticles increases with the extension of the PDMAEMA block. In addition, the double thermo-response behavior of the PS-b-PNIPAM-b-PDMAEMA nanoparticles is detected by turbidity analysis, temperature-dependent 1H-NMR analysis, and DLS analysis. The seeded RAFT polymerization is believed as a valid method to prepare triblock copolymer nanoparticles containing two thermo-responsive blocks.展开更多
The monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly( N-isopropylacrylamide)( PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure( Au@ Ag NR@ PNIPAM ...The monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly( N-isopropylacrylamide)( PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure( Au@ Ag NR@ PNIPAM microgel)by seed-precipitation polymerization method using butenoic acid modified Au @ Ag NRs as seeds. When the temperature of the aqueous medium increases from 20℃ to 50℃,the localized surface plasmon resonance( LSPR) band of the entrapped Au @ Ag NR is pronouncedly red-shifted because of the decreased spatial distances between them as a result of shrinkage of the microgels,leading to their plasmonic coupling. The temperature tunable plasmonic coupling is demonstrated by temperature dependence of the surface enhanced Raman spectroscopy( SERS) signal of 1-naphthol in aqueous solution. Different from static plasmonic coupling modes from nanostructured assembly or array system of noble metals,the proposed plasmonic coupling can be dynamically controlled by environmental temperature. Therefore, the thermo responsive hybrid microgels have potential applications in mobile LSPR or SERS microsensors for living tissues or cells.展开更多
Thermo-responsive multiblock polycarbonates were facilely synthesized by covalently binding poly(ethylene glycol)(PEG) and poly(propylene glycol)(PPG) blocks,using triphosgene as coupling agent and pyridine as catalys...Thermo-responsive multiblock polycarbonates were facilely synthesized by covalently binding poly(ethylene glycol)(PEG) and poly(propylene glycol)(PPG) blocks,using triphosgene as coupling agent and pyridine as catalyst.The aqueous solutions of thermo-responsive polycarbonates were investigated by rheological measurements.Steady-state shear measurements reveal that the polycarbonate solutions exhibit shear-thinning behavior and the hydrophilic content has a pronounced effect on the flow behavior of the polycarbonates aqueous solutions.The shear viscosity decreases with increasing poly(ethylene oxide)(PEO) composition.The increase of viscosity with increasing concentration is probably attributed to the formation of stronger network owing to interchain entanglement of PEO block at higher concentration.When the flow curves are fitted to the power law model,flow index is obtained to be less than 1,as exhibiting typical pesudoplastic fluid.The viscoelastic properties of the system also show close dependence on the composition of polycarbonates.Temperature sweep confirms that the multiblock polycarbonates exhibit thermo-responsive properties.For 7% aqueous solution of polycarbonate with composition ratio of EO to PO of 1/1,the sol-gel transition occurs at 37 ℃,which makes the system suitable as an injectable drug delivery system.展开更多
As a new concept having emerged in last few years,the“deep eutectic solvents”(DESs)effect integrated into the imprinting technology inevitably exposes design limitations of stimuli-responsive molecularly imprinted p...As a new concept having emerged in last few years,the“deep eutectic solvents”(DESs)effect integrated into the imprinting technology inevitably exposes design limitations of stimuli-responsive molecularly imprinted polymers(MIPs),as well as inadequate analysis of the adsorption performance of MIPs.Herein,a simple yet defined N-isopropylacrylamide/(3-acrylamidopropyl)trimethylammonium chloride(NIPAM/APTMAC)binary DESs system was proposed to prepare intelligent MIPs with thermo-sensitivity.Accordingly,magnetic and thermo-responsive MIPs based on functional monomers-derived DESs(TMDESs-MIPs1)were synthesized,revealing DESs effect-regulated affinity/kinetics for the enhanced adsorption capability,eco-friendly thermo-regulated elution for high release efficiency,and simple magnetic separation,along with superior selectivity to rhein(RH)and good regeneration ability.TM-DESs-MIPs1 were utilized to extract RH from Cassiae semen samples coupled with high performance liquid chromatography(HPLC),yielding satisfactory recoveries(79.47%−110.82%)and low limits of detection(LOD)(16.67μg/L).Another two kinds of MIPs adopting the thermo-responsive moiety-derived DESs effect strategy further demonstrated great applicability of such intelligent MIPs for analyses of complicated samples.展开更多
Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted sign...Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted significantly on account of low water permeability and poor dynamic tunability of 2D nanochannels under temperature stimulation.Here,we present a biomimetic negatively thermo-responsive MXene membrane by covalently grafting poly(N-isopropylacrylamide)(PNIPAm)onto MXene nanosheets.The uniformly grafted PNIPAm polymer chains can enlarge the interlayer spacings for increasing water permeability while also allowing more tunability of 2D nanochannels for enhancing the capability of gradually separating multiple molecules of different sizes.As expected,the constructed membrane exhibits ultrahigh water permeance of 95.6 L m^(-2) h^(-1) bar^(-1) at 25℃,which is eight-fold higher than the state-of-the-art negatively thermoresponsive 2D membranes.Moreover,the highly temperature-tunable 2D nanochannels enable the constructed membrane to perform excellent graded molecular sieving for dye-and antibiotic-based ternary mixtures.This strategy provides new perspectives in engineering smart 2D membrane and expands the scope of temperature-responsive membranes,showing promising applications in micro/nanofluidics and molecular separation.展开更多
Thermo-respansive chitosan hydrogel system （TRCHS） was prepared and its mierostructure was investigated by scaning electron microscope （SEM） and mercury intrusion poremaster （MIP）. Based on analyzing the data, a...Thermo-respansive chitosan hydrogel system （TRCHS） was prepared and its mierostructure was investigated by scaning electron microscope （SEM） and mercury intrusion poremaster （MIP）. Based on analyzing the data, a special porosity property was reported at the first time. Its gelling mechanism was studied by a group of contrast experiments. Results may provide experimental and theoretical supports for how to apply it on tissue engineering scaffold and how to influeuee or control its essential properties.展开更多
Thermo-responsive random copolymers,poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-(ethylene glycol)methyl ether methacrylate)(P(EO_(2)-co-EO_(4/5)))and poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-ethylen...Thermo-responsive random copolymers,poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-(ethylene glycol)methyl ether methacrylate)(P(EO_(2)-co-EO_(4/5)))and poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-ethylene glycol methacrylate(P(EO2-co-EG4/5))are synthesized via atom transfer radical polymerization(ATRP).The successful synthesis and the narrow polydispersity index(PDI)of two copolymers are indicated by 1H nuclear magnetic resonance(1H-NMR)and gel permeation chromatography(GPC)analyses.The transition behaviors of polymers in the aqueous solution are demonstrated by changes in turbidity and particle sizes.The transition behavior of P(EO2-co-EG4/5)is found to be milder than that of P(EO2-co-EO4/5).Moreover,the presence of hydrogen bonds without thermo-responsive properties established by hydroxyl groups in the end-side chain of P(EO_(2)-co-EG_(4/5))hinders the dehydration at the transition temperature(TT).Attenuated total reflection Fourier transform infrared spectrometry(ATR-FTIR)analysis along with contact angle measurements reveals that both P(EO_(2)-co-EO_(4/5))and P(EO_(2)-co-EG_(4/5))films undergo phase transitions from hydrophilicity to hydrophobicity above TT.By examining the swelling and collapse behaviors of the polymer films during phase transitions,it can be concluded that the end hydroxyl groups may establish hydrogen bonds with neighboring ether groups within the films,which remain intact throughout the phase transition process due to their strong bonding interactions.This leads to an increase in steric hindrance within swollen films thereby impeding dehydration processes and inducing hysteresis during phase transitions.展开更多
The induction of antitumor immunity by tumor antigens released from cancer cells following regional photothermal therapy(PTT)alone may not be adequate for achieving complete tumor elimination.Combination therapy with ...The induction of antitumor immunity by tumor antigens released from cancer cells following regional photothermal therapy(PTT)alone may not be adequate for achieving complete tumor elimination.Combination therapy with immune adjuvants enhances antitumor immune responses,but faces challenges such as targeting deficiencies,systemic toxicity,and uncontrolled release behavior.Herein,we introduce a novel dual-functional hybrid membrane nanoparticle(HM-NP)incorporating gold nanorods(GNRs)and a thermally responsive polymer shell.HM-NP demonstrates exceptional homotypic targeting efficacy beneath the tumor cell membrane(TM),leading to substantial tumor accumulation.Upon in situ near-infrared(NIR)stimulation,GNRs within HM-NP generate heat,triggering the burst release of HM by facilitating the contraction and disintegration of the thermally responsive polymer shell.HM-NP exhibits excellent photothermal conversion efficiency under NIR irradiation,enabling effective destruction of primary tumors,release of tumor-associated antigens,and stimulation of potent anti-cancer immune.Simultaneously,the immune responses are strengthened by TM and Escherichia coli membrane(EM)through promoting the maturation of antigen presenting cells(APCs)and activating cytotoxic T lymphocytes(CTLs).Moreover,the use of polymer shells enables efficient cancer therapy with minimal host clearance and adverse effects.This photothermally triggered immunotherapy holds promise for precise and personalized treatment of tumors.展开更多
Linear copolymers from N-isopropylacrylamide （NIPA）, acrylic acid （AA） and diacetone acrylamide （DAA） have been prepared. The effect of composition, ionic strength and pH on their lower critical solution tempera...Linear copolymers from N-isopropylacrylamide （NIPA）, acrylic acid （AA） and diacetone acrylamide （DAA） have been prepared. The effect of composition, ionic strength and pH on their lower critical solution temperature （LCST） has been investigated.展开更多
A new kind of hollow hydrogel microfiber with discontinuous hollow structure was prepared by an ice-segregation-induced self-assembly process. Monodisperse thermo-responsive hollow poly（N-isopropylacrylamide）（PNIPA...A new kind of hollow hydrogel microfiber with discontinuous hollow structure was prepared by an ice-segregation-induced self-assembly process. Monodisperse thermo-responsive hollow poly（N-isopropylacrylamide）（PNIPAM） microgels were first synthesized by seed precipitation polymerization using colloidal Si O2 nanoparticles as seeds, followed by removing the silica cores of the formed Si O2/PNIPAM core/shell composite microgels with hydrofluoric acid. Then, the discontinuously hollow hydrogel microfibers were produced by unidirectional freezing of 1 wt% hollow PNIPAM microgel aqueous dispersion in liquid nitrogen bath, followed by freeze-drying to remove the formed ice crystals. Many orderly arrayed dents were observed on the surfaces of the hydrogel microfibers by field-emission scanning electron microscopy, indicating that they are constructed by closely packed monodisperse hollow PNIPAM microgels. The effect of freezing method and the hollow microgel concentration in the aqueous dispersion on the morphological structure of the hollow hydrogel microfibers was investigated.展开更多
Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not bee...Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.展开更多
基金Project supported by the Central Funding Project for Local Science and Technology Development(2022JH6/100100048)the National Natural Science Foundation of China(52103038)Shenyang Science and Technology Plan Project(20-202-1-12)。
文摘A novel Eu^(2+)-Eu^(3+)co-activated ratiometric thermo-sensitive phosphor was developed and synthesized by solid-state reaction.The valence state of Eu,photoluminescence and thermo-sensitive performance of the phosphor prepared either in ambient air or carbothermally were investigated and discussed.The phosphor shows high sensitivity(Sa=0.0173 K^(-1),S_(r)=0.461%/K)and superior signal discriminability(Δν∼10380 cm^(−1)).The thermo-sensitive performance is subject to the dual effects of different thermo-responses by Eu^(2+)versus Eu^(3+)combined with energy transfer from Eu^(2+)to Eu^(3+),so that the sensitivity of the phosphor in the temperature range presents a non-monotonic trend.The development of the BaAl_(2)B_(2)O_(7):Eu^(2+),Eu^(3+)phosphor is not only expected to be relevant for application in the field of temperature sensing,but also of reference significance for improving the sensitivity by means of energy transfer between co-activator ions over a wider temperature range of Eu^(2+)-Eu^(3+)co-activated ratiometric thermo-sensitive phosphors.
基金support by Shandong Provincial Natural Science Foundation(Grant No ZR2024QH150,ZR2024YQ068)Taishan Scholars Program of Shandong Province(Grant No tsqn202306272)+5 种基金National Natural Science Foundation of China(Grant No 82302388)National Key Research and Development Project of China(Grant No 2023YFFO715101)Qingdao Natural Science Foundation(Grant No 23-2-1-132-zyyd-jch)the Leading Project of Science and Technology of Yantai Development Zone(Grant No 2021RC016)National Key RD Program of China(2021YFF1201100)Hubei Key Laboratory of Biomass Fibers&Eco-Dyeing&Finishing(Wuhan Textile University,Grant No STRZ202322).
文摘Efficient reconstruction of severe cutaneous wounds necessitates the orchestration of effective cell-mediated matrix remodeling and robust protection against microbial invasion.Herein,we engineered a near-infrared light(NIR)-stimulated,thermo-responsive bilayer system based on a drug-loaded hydrogel with a thermal-responsive temperature of~42℃ as the matrix layer and an antibacterial nanofibrous mat as the top layer.The matrix layer integrates basic fibroblast growth factor(bFGF)-loaded thermosensitive gelatin(Gel)hydrogel with polydopamine-Cu^(2+)coated short nanofibers(P@SF).Upon NIR exposure,P@SF elicits a photothermal effect,causing a rapid increase in temperature by 13.4℃ within 1 min at a power density of 0.75 W/cm^(2),which triggers the gel-sol transition of Gel and controls the release of bFGF.This,in turn,enhances fibroblast and endothelial cells ingrowth into the hydrogel,fostering cell functionalization and matrix remodeling.The top layer consists of poly(L-lactide-co-caprolactone)nanofibers functionalized with lysine-doped polydopamine and poly-l-lysine.It possesses antibacterial efficacy by isolating,controlling(76.23%for E.coli and 89.16%for S.aureus),and eliminating bacteria upon NIR activation.In rat skin wound models,this NIR-responsive smart bilayer system prevents S.aureus-mediated bacterial infection(indicative of reduced IL-6 expression),regulates CD31-positive neovascularization,and facilitates collagen remodeling for skin regeneration.In summary,this study introduces a novel strategy,inspired by the centralization of authority,for developing a smart thermo-responsive system with promising potential for the effective reconstruction of severe cutaneous wounds.
基金Supported by the National Natural Science Foundation of China(No.29876022).
文摘The effect of graft yield on both the thermo-responsive hydraulicpermeability and the therrno-responsive diffusional permeability through porous membranes withplasma-grafted poly(N-isopropylacrylamide) (PNIPAM) gates was investigated. Both thermo-responsiveflat membranes and core-shell microcapsule membranes with a wide range of graft yield of PNIPAM wereprepared using a plasma-graft pore-filling polymerization method. The grafted PNIPAM was formedhomogeneously throughout the entire thickness of both the flat polyethylene membranes and themicrocapsule polyamide membranes. Both the hydraulic permeability and the diffusional permeabilitywere heavily dependent on the PNIPAM graft yield. With increasing the graft yield, the hydraulicpermeability (water flux) decreases rapidly at 25℃ because of the decrease of the pore size;however, the water flux at 40℃ increases firstly to a peak because of the increase ofhydrophobicity of the pore surface, and then decreases and finally tends to zero because of the poresize becoming smaller and smaller. For the diffusional permeability, the temperature showsdifferent effects on the diffusional permeability coefficients of solutes across the membranes. Whenthe graft yield was low, the diffusional coefficient of solute across the membrane was higher attemperature above the lower critical solution temperature (LCST) than that below the LCST; however,when the graft yield was high, the diffusional coefficient was lower at temperature above the LCSTthan that below the LCST. It is very important to choose or design a proper graft yield of PNIPAMfor obtaining a desired thermo-responsive 'on/off' hydraulic or diffusional permeability.
基金Supported by the National ]qatural Science Foundation of China （20906064）, the National Basic Research Program of China （2009CB623407）, the Program for Changjiang Scholars and Innovative Research Team in University （IRTl163）, and the Foundation for the Author of National Excellent Doctoral Dissertation of China （201163）.
文摘Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide （NIPAM） with silane-modified halloysite nanotubes （HNT） through thermally initiated free-radical polymerization. With methylene blue as a model drug, thermo-responsive drug release results demonstrate that the drug release from the nanotubes in the composited hy-drogel can^be well controlled by manipulating the environmental temperature. When the hydrogel network is swol- len at temperature below the lower critical solution temperature （LCST）, drug releases steadily from lumens of the embedded nanotubes, whereas the drug release stops when hydrogel shrinks at temperature above the LCST. The release of model drug from the HNT-composited hydrogel matches well with its thermo-responsive volume phasetransition, and shows characteristics of well controlled release. The design strategy and release results of the pro- posed novel HNT-composited thermo-responsive hydrogel system provide valuable guidance for designing respon- s_i_ve nanocomposites for controlled-release of active agents.
基金financially supported by the National Natural Science Foundation of China(No.51303028)the Natural Science Foundation of Fujian Province(No.2011J01044)
文摘A novel hydrophilic nanocomposite additive （TiO2-g-PNIPAAm） was synthesized by the surface modification of titanium dioxide （TiO2） with N-isopropylacrylamide （NIPAAm） via ＂graft-from＂ technique. And the nanocomposite membrane of poly（vinylidene fluoride） （PVDF）/TiO2-g-PNIPAAm was fabricated by wet phase inversion. The graft degree was obtained by thermo-gravimetric analysis （TGA）. Fourier transform infrared attenuated reflection spectroscopy （FTIR-ATR） and X-ray photoelectronic spectroscopy （XPS） characterization results suggested that TiO2-g-PNIPAAm nanoparticles segregated on membrane surface during the phase separation process. Scanning electron microscopy （SEM） was conducted to investigate the surface and cross-section of the modified membranes. The water contact angle measurements confirmed that TiO2-g-PNIPAAm nanoparticles endowed PVDF membranes better hydrophlilicity and thermo-responsive properties compared with those of the pristine PVDF membrane. The water contact angle decreased from 92.8~ of the PVDF membrane to 61.2~ of the nanocompostie membrane. Bovine serum albumin （BSA） static and dynamic adsorption experiments suggested that excellent antifouling properties of membranes was acquired after adding TiO2-g- PNIPAAm. The maximum BSA adsorption at 40℃ was about 3 times than that at 23 ℃. The permeation experiments indicated the water flux recover ratio and BSA rejection ratio were improved at different temperatures.
基金financially supported by the National Natural Science Foundation of China(No.21674086)Scientific Research Program Funded by Shaanxi Provincial Education Department(No.17JK0103)
文摘Despite the fact that some progress has been made in the self-assembly of H-shaped polymers, the corresponding self-assemblies that respond to external stimulus and are further utilized to adjust the release of drugs are still deficient. The stimuli-responsive segments with amphiphilic H-shaped structure are generally expected to enhance the controllability of self-assembly process. The synthesis and self-assembly behavior of thermo-responsive amphiphilic H-shaped polymers with poly（ethylene glycol） （PEG）, polytetrahydrofuran （PTHF） and poly（N-isopropyl acrylamide） （PNIPAM） as building blocks are reported in this paper. The inner architecture structure and size of complex micelles formed by H-shaped self-assemblies were effectively adjusted when the solution temperature was increased above the lower critical solution temperature of PNIPAM segments. Furthermore, it was found that the architecture of self-assemblies underwent a transition from the complex micelles based on primary micelles with hybrid PEG/PNIPAM shells to large complex micelles based on primary micelles with hybrid PTHF/PNIPAM cores and PEG shells during the thermal-induced self-assembly process. The adjustable release rate ofdoxorubicin （DOX） from the DOX-loaded complex micelles and basic cell experiments further proved the feasibility of these self-assemblies as the thermal-responsive drug delivery system.
基金financially supported by the National Natural Science Foundation of China(Nos.51233005,21374114,and21274152)
文摘Thermo-responsive butyl acrylate/furfuryl methacrylate copolymer-based （PBF backbone） graft （co）polymers with dynamic covalent linkages between their backbones and side chains via the Diels-Alder reaction of furardmaleimide were synthesized. Atom transfer radical polymerization （ATRP） was used to synthesize graft copolymers with thermo-responsive transformation from graft copolymers to linear polymers with bimodal or wide MWD. The NMR measurements indicated that the Diels-Alder reaction and retro- Diels-Alder reaction occurred, depending on the change of the temperature, meaning that the side chains could be cleaved and reformed according to the variation of the temperature. GPC measurements demonstrated that the molecular weights of the polymers were thermo- responsive. Furthermore, three graft copolymers with various branching chains （PBF-g-PBA, PBF-g-P（BMA-co-MA） and PBF-g-PBMA） were compared to study the influence of compatibility between the backbone and the branching chain on the efficiency of Diels-Alder reaction after the cleavage of the DA linkage. The results showed that the ability of the side chains to come back to the main chain was strongly affected by the compatibility between the backbone and the side chains and the flexibility of the polymer chains.
文摘Therrno-responsive block copolymers poly（ethylene glycol）-block-poly（N-acryloyl-2,2-dimethyl-1,3-oxazolidine）, PEG-b-PADMO, based on linear PEG were prepared via a versatile reversible addition-fragmentation chain transfer （RAFT） polymerization, PEG22 （Mw = 1000） was used as the hydrophilic component, whose dehydration was the main driving force for the phase transition of these copolymers, as demonstrated by the tH-NMR spectra. Their lower critical solution temperatures （LCSTs） could be tuned in the range of 20℃ to 35℃, by adjusting the degree of polymerization （DP） of PADMO between 14-27. Furthermore, a sharp phase transition at ca. 33℃, close to the physiological temperature with minimal hysteresis, was observed for the PEGzz-b-PADMO14 copolymer. Moreover, excellent reversibility and reproducibility were displayed for the same copolymer over 10 cycles of repeated temperature change between 25℃ （below the LCST） and 40℃ （above the LCST）.
基金financially supported by Foundation of State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry
文摘In this work,the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature(LCST)of the macroporous thermo-responsive poly(N-isopropylacrylamide)grafted poly(vinyl alcohol)formaldehyde(PVF-g-PNIPAM)hydrogels are investigated with differential scanning calorimetry(DSC).Four kinds of anions with strong hydration,including CO3^2–,SO4^2–,S2 O3^2–,and F^–,and four kinds of anions with weak hydration,including Br^–,NO3^–,I^–,and ClO4^–,and Cl^–as a medium anion are systematically studied and found to demonstrate the effects of the residual hydroxyl groups and network structure of PVF on the LCST values of PVF-g-PNIPAM hydrogels in comparison with that of neat PNIPAM.On the one hand,the existence of hydroxyl groups on PVF backbone promotes the solubility of grafted PNIPAM due to their hydrophilicity and hydrogen-bond interactions with water.On the other hand,the network structure of as-prepared samples restricts free movements of grafted PNIPAM chains,which results in the increase of LCST values.In addition,the difference of grafting percentage also influences the variation of LCST values of PVF-g-PNIPAM hydrogels under salt concentration.
基金financially supported by 973 Program of China,under the contract(No.2015CB655105)the National Science Fund for Distinguished Young Scholars(No.51225801)+1 种基金the National Natural Science Foundation of China(No.51408275)the Provincial Science and Technology Cooperation Project of Jiangsu-Guangxi cooperation project(No.BM2014050)
文摘The doubly thermo-responsive triblock copolymer nanoparticles of polystyrene-block-poly（N- isopropylacrylamide）-block-poly[N,N-（dimethylamino） ethyl methacrylate] （PS-b-PNIPAM-b-PDMAEMA） are successfully prepared through the seeded RAFT polymerization in situ by using the PS-b-PNIPAM-TTC diblock copolymer nanoparticles as the seed. The seeded RAFT polymerization undergoes a pseudo-first-order kinetics procedure, and the molecular weight increases with the monomer conversion linearly. The hydrodynamic diameter （Dh） of the triblock copolymer nanoparticles increases with the extension of the PDMAEMA block. In addition, the double thermo-response behavior of the PS-b-PNIPAM-b-PDMAEMA nanoparticles is detected by turbidity analysis, temperature-dependent 1H-NMR analysis, and DLS analysis. The seeded RAFT polymerization is believed as a valid method to prepare triblock copolymer nanoparticles containing two thermo-responsive blocks.
基金National Natural Science Foundation of China(No.51373030)Chinese Universities Scientific Fund(No.CUSF-DH-D-2014023)
文摘The monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly( N-isopropylacrylamide)( PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure( Au@ Ag NR@ PNIPAM microgel)by seed-precipitation polymerization method using butenoic acid modified Au @ Ag NRs as seeds. When the temperature of the aqueous medium increases from 20℃ to 50℃,the localized surface plasmon resonance( LSPR) band of the entrapped Au @ Ag NR is pronouncedly red-shifted because of the decreased spatial distances between them as a result of shrinkage of the microgels,leading to their plasmonic coupling. The temperature tunable plasmonic coupling is demonstrated by temperature dependence of the surface enhanced Raman spectroscopy( SERS) signal of 1-naphthol in aqueous solution. Different from static plasmonic coupling modes from nanostructured assembly or array system of noble metals,the proposed plasmonic coupling can be dynamically controlled by environmental temperature. Therefore, the thermo responsive hybrid microgels have potential applications in mobile LSPR or SERS microsensors for living tissues or cells.
基金Projects(2006GG2203007) supported by the Scientific Research Project of Shandong Province,China
文摘Thermo-responsive multiblock polycarbonates were facilely synthesized by covalently binding poly(ethylene glycol)(PEG) and poly(propylene glycol)(PPG) blocks,using triphosgene as coupling agent and pyridine as catalyst.The aqueous solutions of thermo-responsive polycarbonates were investigated by rheological measurements.Steady-state shear measurements reveal that the polycarbonate solutions exhibit shear-thinning behavior and the hydrophilic content has a pronounced effect on the flow behavior of the polycarbonates aqueous solutions.The shear viscosity decreases with increasing poly(ethylene oxide)(PEO) composition.The increase of viscosity with increasing concentration is probably attributed to the formation of stronger network owing to interchain entanglement of PEO block at higher concentration.When the flow curves are fitted to the power law model,flow index is obtained to be less than 1,as exhibiting typical pesudoplastic fluid.The viscoelastic properties of the system also show close dependence on the composition of polycarbonates.Temperature sweep confirms that the multiblock polycarbonates exhibit thermo-responsive properties.For 7% aqueous solution of polycarbonate with composition ratio of EO to PO of 1/1,the sol-gel transition occurs at 37 ℃,which makes the system suitable as an injectable drug delivery system.
基金National Key Research and Development Project(No.2019YFC1604904)National Natural Science Foundation of China(No.32101212)+1 种基金Natural Science Foundation of Jiangxi(No.20224ACB215009)Research Program of State Key Laboratory of Food Science and Technology in Nanchang University(No.SKLF-ZZB-202127).
文摘As a new concept having emerged in last few years,the“deep eutectic solvents”(DESs)effect integrated into the imprinting technology inevitably exposes design limitations of stimuli-responsive molecularly imprinted polymers(MIPs),as well as inadequate analysis of the adsorption performance of MIPs.Herein,a simple yet defined N-isopropylacrylamide/(3-acrylamidopropyl)trimethylammonium chloride(NIPAM/APTMAC)binary DESs system was proposed to prepare intelligent MIPs with thermo-sensitivity.Accordingly,magnetic and thermo-responsive MIPs based on functional monomers-derived DESs(TMDESs-MIPs1)were synthesized,revealing DESs effect-regulated affinity/kinetics for the enhanced adsorption capability,eco-friendly thermo-regulated elution for high release efficiency,and simple magnetic separation,along with superior selectivity to rhein(RH)and good regeneration ability.TM-DESs-MIPs1 were utilized to extract RH from Cassiae semen samples coupled with high performance liquid chromatography(HPLC),yielding satisfactory recoveries(79.47%−110.82%)and low limits of detection(LOD)(16.67μg/L).Another two kinds of MIPs adopting the thermo-responsive moiety-derived DESs effect strategy further demonstrated great applicability of such intelligent MIPs for analyses of complicated samples.
基金supported by the National Nature Science Foundation of China(No.22278179,U23A20688)the National Key Research and Development Program of China(2021YFB3802600)+3 种基金the Fundamental Research Funds for the Central Universities(JUSRP622035)National First-Class Discipline Program of Light Industry Technology and Engineering(LIFE2018-19)MOE&SAFEA for the 111 Project(B13025)Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01D030).
文摘Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted significantly on account of low water permeability and poor dynamic tunability of 2D nanochannels under temperature stimulation.Here,we present a biomimetic negatively thermo-responsive MXene membrane by covalently grafting poly(N-isopropylacrylamide)(PNIPAm)onto MXene nanosheets.The uniformly grafted PNIPAm polymer chains can enlarge the interlayer spacings for increasing water permeability while also allowing more tunability of 2D nanochannels for enhancing the capability of gradually separating multiple molecules of different sizes.As expected,the constructed membrane exhibits ultrahigh water permeance of 95.6 L m^(-2) h^(-1) bar^(-1) at 25℃,which is eight-fold higher than the state-of-the-art negatively thermoresponsive 2D membranes.Moreover,the highly temperature-tunable 2D nanochannels enable the constructed membrane to perform excellent graded molecular sieving for dye-and antibiotic-based ternary mixtures.This strategy provides new perspectives in engineering smart 2D membrane and expands the scope of temperature-responsive membranes,showing promising applications in micro/nanofluidics and molecular separation.
文摘Thermo-respansive chitosan hydrogel system （TRCHS） was prepared and its mierostructure was investigated by scaning electron microscope （SEM） and mercury intrusion poremaster （MIP）. Based on analyzing the data, a special porosity property was reported at the first time. Its gelling mechanism was studied by a group of contrast experiments. Results may provide experimental and theoretical supports for how to apply it on tissue engineering scaffold and how to influeuee or control its essential properties.
基金Fujian External Cooperation project of Natural Science Foundation,China(No.2022I0042)。
文摘Thermo-responsive random copolymers,poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-(ethylene glycol)methyl ether methacrylate)(P(EO_(2)-co-EO_(4/5)))and poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-ethylene glycol methacrylate(P(EO2-co-EG4/5))are synthesized via atom transfer radical polymerization(ATRP).The successful synthesis and the narrow polydispersity index(PDI)of two copolymers are indicated by 1H nuclear magnetic resonance(1H-NMR)and gel permeation chromatography(GPC)analyses.The transition behaviors of polymers in the aqueous solution are demonstrated by changes in turbidity and particle sizes.The transition behavior of P(EO2-co-EG4/5)is found to be milder than that of P(EO2-co-EO4/5).Moreover,the presence of hydrogen bonds without thermo-responsive properties established by hydroxyl groups in the end-side chain of P(EO_(2)-co-EG_(4/5))hinders the dehydration at the transition temperature(TT).Attenuated total reflection Fourier transform infrared spectrometry(ATR-FTIR)analysis along with contact angle measurements reveals that both P(EO_(2)-co-EO_(4/5))and P(EO_(2)-co-EG_(4/5))films undergo phase transitions from hydrophilicity to hydrophobicity above TT.By examining the swelling and collapse behaviors of the polymer films during phase transitions,it can be concluded that the end hydroxyl groups may establish hydrogen bonds with neighboring ether groups within the films,which remain intact throughout the phase transition process due to their strong bonding interactions.This leads to an increase in steric hindrance within swollen films thereby impeding dehydration processes and inducing hysteresis during phase transitions.
基金supported by the National Natural Science Foundation of China(Nos.92059112,82072821 and 31470964)University of Shanghai for Science and Technology(No.10-21302-405)+1 种基金the Program of Shanghai Academic/Technology Research Leader(No.22XD1404700)the Shanghai Songjiang Municipal Science and Technology Commission Natural Science Foundation(No.20SJKJGG250)。
文摘The induction of antitumor immunity by tumor antigens released from cancer cells following regional photothermal therapy(PTT)alone may not be adequate for achieving complete tumor elimination.Combination therapy with immune adjuvants enhances antitumor immune responses,but faces challenges such as targeting deficiencies,systemic toxicity,and uncontrolled release behavior.Herein,we introduce a novel dual-functional hybrid membrane nanoparticle(HM-NP)incorporating gold nanorods(GNRs)and a thermally responsive polymer shell.HM-NP demonstrates exceptional homotypic targeting efficacy beneath the tumor cell membrane(TM),leading to substantial tumor accumulation.Upon in situ near-infrared(NIR)stimulation,GNRs within HM-NP generate heat,triggering the burst release of HM by facilitating the contraction and disintegration of the thermally responsive polymer shell.HM-NP exhibits excellent photothermal conversion efficiency under NIR irradiation,enabling effective destruction of primary tumors,release of tumor-associated antigens,and stimulation of potent anti-cancer immune.Simultaneously,the immune responses are strengthened by TM and Escherichia coli membrane(EM)through promoting the maturation of antigen presenting cells(APCs)and activating cytotoxic T lymphocytes(CTLs).Moreover,the use of polymer shells enables efficient cancer therapy with minimal host clearance and adverse effects.This photothermally triggered immunotherapy holds promise for precise and personalized treatment of tumors.
文摘Linear copolymers from N-isopropylacrylamide （NIPA）, acrylic acid （AA） and diacetone acrylamide （DAA） have been prepared. The effect of composition, ionic strength and pH on their lower critical solution temperature （LCST） has been investigated.
基金supported by the National Natural Science Foundation of China(Nos.51073033 and 51373030)the Fundamental Research Funds for the Central Universities(No.2232014D3-43)
文摘A new kind of hollow hydrogel microfiber with discontinuous hollow structure was prepared by an ice-segregation-induced self-assembly process. Monodisperse thermo-responsive hollow poly（N-isopropylacrylamide）（PNIPAM） microgels were first synthesized by seed precipitation polymerization using colloidal Si O2 nanoparticles as seeds, followed by removing the silica cores of the formed Si O2/PNIPAM core/shell composite microgels with hydrofluoric acid. Then, the discontinuously hollow hydrogel microfibers were produced by unidirectional freezing of 1 wt% hollow PNIPAM microgel aqueous dispersion in liquid nitrogen bath, followed by freeze-drying to remove the formed ice crystals. Many orderly arrayed dents were observed on the surfaces of the hydrogel microfibers by field-emission scanning electron microscopy, indicating that they are constructed by closely packed monodisperse hollow PNIPAM microgels. The effect of freezing method and the hollow microgel concentration in the aqueous dispersion on the morphological structure of the hollow hydrogel microfibers was investigated.
基金financially supported by the National Natural Science Foundation of China(Grant No.52150410427)the Key Support Program for Foreign Experts of the Ministry of Science and Technology of the People's Republic of China(No.wgxz2022057)funding for post-doctoral work by the Department of Human Resources and Social Security of Hubei Province。
文摘Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.
