Nanomaterials are frequently employed in daily life goods,including health,textile,and food industry.A comprehensive picture is lacking on the role of the capping agents,added ligand molecules,in case of nanoparticle ...Nanomaterials are frequently employed in daily life goods,including health,textile,and food industry.A comprehensive picture is lacking on the role of the capping agents,added ligand molecules,in case of nanoparticle reactions and degradation in aqueous solutions,like surface waters or biofluids.Here,we aim to elucidate the capping agent influence on nanoparticle reactivity probing two commonly employed capping agents citrate and polyvinylpyrrolidone(PVP).Their influence on silver nanoparticle(AgNP)transformation is studied,which is particularly important due to its application as an antimicrobial agent.We induce oxidation and reduction processes of AgNPs in halide solutions and we monitor the associated transformations of particles and capping agents by spectro-electrochemical surface-enhanced Raman spectroscopy(SERS).Raman bands of the capping agents are used here to track chemical changes of the nanoparticles under operando conditions.The sparingly soluble and non-plasmon active silver salts(AgBr and AgCl)are formed under potential bias.In addition,we spectroscopically observe plasmon-mediated structural changes of citrate to cis-or trans-aconitate,while PVP is unaltered.The different behavior of the capping agents implies a change in the physical properties on the surface of AgNPs,in particular with respect to the surface accessibility.Moreover,we showcase that reactions of the capping agents induced by different external stimuli,such as applied bias or laser irradiation,can be assessed.Our results demonstrate how SERS of capping agents can be exploited to operando track nanoparticle conversions in liquid media.This approach is envisaged to provide a more comprehensive understanding of nanoparticle fates in complex liquid environments and varied redox conditions.展开更多
Of several noble metal nanoparticles,silver nanoparticles(AgNPs)have attracted special attention due to their distinct properties,such as favorable electrical conductivity,chemical stability,and catalytic and antibact...Of several noble metal nanoparticles,silver nanoparticles(AgNPs)have attracted special attention due to their distinct properties,such as favorable electrical conductivity,chemical stability,and catalytic and antibacterial activities.Green synthesis of AgNPs using plant extracts containing phytochemical agents has attracted considerable interest.This environmentally friendly approach is more biocompatible and costefficient and has the capability of supporting large-scale synthesis.This study developed an eco-friendly method for the preparation of AgNPs using the aqueous leaf extract of Saussurea obvallata as reducing and capping agents.Ultraviolet visible spectroscopy(UV-is),Fourier transform infrared spectroscopy(FTIR),Raman,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),and transmission electron microscopy(TEM)analyses were conducted to characterize the synthesized AgNPs.The morphology of AgNPs was found to be spherical with an average crystallite size of 12 nm and a maximum absorbance at 410 nm.10 mg of AgNPs had potential to reduce 4-nitrophenol to 4-aminophenol in 16 min and exhibited strong biological activities against the Gram-negative bacteria Escherichia coli(12 mm)and Gram-positive bacteria Enterococcus faecalis(13 mm).The antioxidant activity of the synthesized AgNPs was investigated against the 2,2-diphenyl-1-picrylhydrazyl(DPPH)radical scavenging and exhibited up to 61.21%±0.02%at an AgNPs concentration of 500 mg/mL.展开更多
Eu3＋ doped CaWO4 with tetragonal system were prepared at comparatively low temperature （125 ℃） in ethylene glycol medium. The phosphor was further investigated by X-ray difffactometer （XRD）, photoluminescence sp...Eu3＋ doped CaWO4 with tetragonal system were prepared at comparatively low temperature （125 ℃） in ethylene glycol medium. The phosphor was further investigated by X-ray difffactometer （XRD）, photoluminescence spectrophotometer （PL）, Fourier transform infra red （FT-IR） spectroscopy and transmission electron microscopy （TEM）. XRD analysis indicated a decrease in the unit cell volume of CaWO4 with increasing Eu3＋ ion concentration. It indicated the homogeneous substitution of Ca2＋ ions in CaWO4 by the Eu3＋ ions. TEM images showed that the particle size ranged from 20 to 200 nm and it could extend the application of the nanoparticles. The photoluminescence study showed that the intensity of electric dipole transition （SD0→TF2） at 614 nm dominated over the magnetic dipole transition （SD0→TFx） at 592 nm. The optimum concentration of Eu3＋ for the highest luminescence was found to be 20 at.%. The as prepared samples were found to be dispersible in water and methanol.展开更多
Silver nanorods have been successfully synthesized in large scale by the ethylene glycol（EG） reduction in the presence of ionic liquid（IL） 1-butyl-3-methylimidazolium tetrafluoroborate（bmimBF_4） and polyvinyl-py...Silver nanorods have been successfully synthesized in large scale by the ethylene glycol（EG） reduction in the presence of ionic liquid（IL） 1-butyl-3-methylimidazolium tetrafluoroborate（bmimBF_4） and polyvinyl-pyrrolidone（PVP）.The silver nanorods were characterized by scanning electron microscopy（SEM）,high-resolution transmission electron microscopy（HRTEM）,transmission electron microscopy（TEM）,electron energy disperse spectroscopy（EDS） and UV-vis spectroscopy.The results showed that the uniform silver nanorods have an average diameter of about 100 nm and the aspect ratio from 15 to 20.IL,bmimBF_4 may play a role of capping agent together with PVP in the formation of silver nanorods.On the other band,bmimBF_4 may accelerate nucleation and improve the stability of the resulting Ag nanorods due to the low interface tension of IL.展开更多
β-FeOOH nanorods of 40 nm wide and 450 nm long were fabricated through precisely regulating the hydrolysis kinetics of Fe^(3+)in polyethylene glycol and the concentration of C1-as the structure-directing agent.Detail...β-FeOOH nanorods of 40 nm wide and 450 nm long were fabricated through precisely regulating the hydrolysis kinetics of Fe^(3+)in polyethylene glycol and the concentration of C1-as the structure-directing agent.Detailed structural and chemical analyses of the intermediates during the synthesis identified that the strong interaction between PEG and Fe^(3+)modulated the hydrolysis kinetics of Fe^(3+)and prevented the aggregation ofβ-FeOOH nanorods;while C1-provided sufficient nucleation sites,stabilized the hollow channel ofβ-FeOOH,and more importantly induced the growth of the nanorods along[001]direction.展开更多
Particle size and shape of cells are essential determining the outcome of drug delivery of nano carrier for medical applications.In this study,different size silver nanoparticles were controllably synthesized to treat...Particle size and shape of cells are essential determining the outcome of drug delivery of nano carrier for medical applications.In this study,different size silver nanoparticles were controllably synthesized to treat two shapes of cells.Silver nanoparticles(AgNPs)were synthesized via chemical reduction using NaBH4 and modified with polyvinylpyrrolidone(PVP)and bovine serum albumin(BSA)or encapsulated in liposomes to enhance cellular uptake.Different nanoparticle sizes were obtained as follows:uncapped AgNPs(30 nm),PVP–AgNPs(34.7 nm),BSA–AgNPs(113.9–145.2 nm),and liposome-encapsulated AgNPs(70.9–142.0 nm).Liposomes with a 5:3 molar ratio of dipalmitoylphosphatidylcholine(DPPC)-to-cholesterol formed stable vesicles,each encapsulating up to 66 AgNPs at a concentration of 2 mmol/L.Cytotoxicity assays revealed that uncapped 2 mM AgNPs exhibited strong toxicity toward both Caco-2 and U251 cells(IC_(50):13.52μmol/L at 24 h).Liposomal AgNPs displayed concentration-dependent effects,with 1 mM AgNPs–liposomes exhibiting the highest toxicity toward Caco-2 cells(IC_(50):0.5μmol/L at 24 h),but significantly lower toxicity toward U251 cells(IC_(50):134.3μmol/L at 24 h).The formulation exhibiting the highest toxicity at 48 h was 2 mmol/L AgNPs–liposomes against Caco-2 cells(IC_(50):4.6μmol/L).In contrast,BSA and PVP coatings significantly reduced toxicity,with IC_(50) of 2.2μmol/L for 50 mmol/L BSA–AgNPs and 14.9μmol/L for 50 mmol/L PVP–AgNPs in Caco-2 cells.Liposome-encapsulated AgNPs showed enhanced toxicity against square-shaped Caco-2 cells compared to fibroblast-like U251 cells(p<0.05),highlighting their potential for targeted cancer therapy.The findings of this study demonstrate that surface modifications and encapsulation strategies critically influence the biological effects of AgNPs in liposomes,providing a promising approach for enhanced anticancer activity.展开更多
基金K.W.acknowledges the German Chemical Industry Fund(FCI Kekule Stipendium).This work was supported by the Research Training group“Confinement-controlled Chemistry”funded by the Deutsche Forschungsgemeinschaft(DFG)(No.GRK2376/331085229)K.T.thanks the Ministry of Innovation,Science and Research of North Rhine-Westphalia for funds(NRW Ruckkehrerprogramm)+1 种基金This work was funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy-EXC 2033-90677874-RESOLV and the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(MITICATgrant agreement No.949724).
文摘Nanomaterials are frequently employed in daily life goods,including health,textile,and food industry.A comprehensive picture is lacking on the role of the capping agents,added ligand molecules,in case of nanoparticle reactions and degradation in aqueous solutions,like surface waters or biofluids.Here,we aim to elucidate the capping agent influence on nanoparticle reactivity probing two commonly employed capping agents citrate and polyvinylpyrrolidone(PVP).Their influence on silver nanoparticle(AgNP)transformation is studied,which is particularly important due to its application as an antimicrobial agent.We induce oxidation and reduction processes of AgNPs in halide solutions and we monitor the associated transformations of particles and capping agents by spectro-electrochemical surface-enhanced Raman spectroscopy(SERS).Raman bands of the capping agents are used here to track chemical changes of the nanoparticles under operando conditions.The sparingly soluble and non-plasmon active silver salts(AgBr and AgCl)are formed under potential bias.In addition,we spectroscopically observe plasmon-mediated structural changes of citrate to cis-or trans-aconitate,while PVP is unaltered.The different behavior of the capping agents implies a change in the physical properties on the surface of AgNPs,in particular with respect to the surface accessibility.Moreover,we showcase that reactions of the capping agents induced by different external stimuli,such as applied bias or laser irradiation,can be assessed.Our results demonstrate how SERS of capping agents can be exploited to operando track nanoparticle conversions in liquid media.This approach is envisaged to provide a more comprehensive understanding of nanoparticle fates in complex liquid environments and varied redox conditions.
文摘Of several noble metal nanoparticles,silver nanoparticles(AgNPs)have attracted special attention due to their distinct properties,such as favorable electrical conductivity,chemical stability,and catalytic and antibacterial activities.Green synthesis of AgNPs using plant extracts containing phytochemical agents has attracted considerable interest.This environmentally friendly approach is more biocompatible and costefficient and has the capability of supporting large-scale synthesis.This study developed an eco-friendly method for the preparation of AgNPs using the aqueous leaf extract of Saussurea obvallata as reducing and capping agents.Ultraviolet visible spectroscopy(UV-is),Fourier transform infrared spectroscopy(FTIR),Raman,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),and transmission electron microscopy(TEM)analyses were conducted to characterize the synthesized AgNPs.The morphology of AgNPs was found to be spherical with an average crystallite size of 12 nm and a maximum absorbance at 410 nm.10 mg of AgNPs had potential to reduce 4-nitrophenol to 4-aminophenol in 16 min and exhibited strong biological activities against the Gram-negative bacteria Escherichia coli(12 mm)and Gram-positive bacteria Enterococcus faecalis(13 mm).The antioxidant activity of the synthesized AgNPs was investigated against the 2,2-diphenyl-1-picrylhydrazyl(DPPH)radical scavenging and exhibited up to 61.21%±0.02%at an AgNPs concentration of 500 mg/mL.
基金Project supported by the Department of Science and Technology (DST), New Delhi, Govt. of India
文摘Eu3＋ doped CaWO4 with tetragonal system were prepared at comparatively low temperature （125 ℃） in ethylene glycol medium. The phosphor was further investigated by X-ray difffactometer （XRD）, photoluminescence spectrophotometer （PL）, Fourier transform infra red （FT-IR） spectroscopy and transmission electron microscopy （TEM）. XRD analysis indicated a decrease in the unit cell volume of CaWO4 with increasing Eu3＋ ion concentration. It indicated the homogeneous substitution of Ca2＋ ions in CaWO4 by the Eu3＋ ions. TEM images showed that the particle size ranged from 20 to 200 nm and it could extend the application of the nanoparticles. The photoluminescence study showed that the intensity of electric dipole transition （SD0→TF2） at 614 nm dominated over the magnetic dipole transition （SD0→TFx） at 592 nm. The optimum concentration of Eu3＋ for the highest luminescence was found to be 20 at.%. The as prepared samples were found to be dispersible in water and methanol.
基金supported by the National Natural Science Foundation of China(No.20773081 and 20873074)National Basic Research Program(No.2007CB808004 and 2009CB930101)Laboratory of Organic Optoelectronic Functional Materials and Molecular Engineering,TIPC,CAS.
文摘Silver nanorods have been successfully synthesized in large scale by the ethylene glycol（EG） reduction in the presence of ionic liquid（IL） 1-butyl-3-methylimidazolium tetrafluoroborate（bmimBF_4） and polyvinyl-pyrrolidone（PVP）.The silver nanorods were characterized by scanning electron microscopy（SEM）,high-resolution transmission electron microscopy（HRTEM）,transmission electron microscopy（TEM）,electron energy disperse spectroscopy（EDS） and UV-vis spectroscopy.The results showed that the uniform silver nanorods have an average diameter of about 100 nm and the aspect ratio from 15 to 20.IL,bmimBF_4 may play a role of capping agent together with PVP in the formation of silver nanorods.On the other band,bmimBF_4 may accelerate nucleation and improve the stability of the resulting Ag nanorods due to the low interface tension of IL.
基金supported by the National Natural Science Foundation of China(21025312,21303193,21321002)the National Key Basic Research Program of China(2013CB933100)
文摘β-FeOOH nanorods of 40 nm wide and 450 nm long were fabricated through precisely regulating the hydrolysis kinetics of Fe^(3+)in polyethylene glycol and the concentration of C1-as the structure-directing agent.Detailed structural and chemical analyses of the intermediates during the synthesis identified that the strong interaction between PEG and Fe^(3+)modulated the hydrolysis kinetics of Fe^(3+)and prevented the aggregation ofβ-FeOOH nanorods;while C1-provided sufficient nucleation sites,stabilized the hollow channel ofβ-FeOOH,and more importantly induced the growth of the nanorods along[001]direction.
文摘Particle size and shape of cells are essential determining the outcome of drug delivery of nano carrier for medical applications.In this study,different size silver nanoparticles were controllably synthesized to treat two shapes of cells.Silver nanoparticles(AgNPs)were synthesized via chemical reduction using NaBH4 and modified with polyvinylpyrrolidone(PVP)and bovine serum albumin(BSA)or encapsulated in liposomes to enhance cellular uptake.Different nanoparticle sizes were obtained as follows:uncapped AgNPs(30 nm),PVP–AgNPs(34.7 nm),BSA–AgNPs(113.9–145.2 nm),and liposome-encapsulated AgNPs(70.9–142.0 nm).Liposomes with a 5:3 molar ratio of dipalmitoylphosphatidylcholine(DPPC)-to-cholesterol formed stable vesicles,each encapsulating up to 66 AgNPs at a concentration of 2 mmol/L.Cytotoxicity assays revealed that uncapped 2 mM AgNPs exhibited strong toxicity toward both Caco-2 and U251 cells(IC_(50):13.52μmol/L at 24 h).Liposomal AgNPs displayed concentration-dependent effects,with 1 mM AgNPs–liposomes exhibiting the highest toxicity toward Caco-2 cells(IC_(50):0.5μmol/L at 24 h),but significantly lower toxicity toward U251 cells(IC_(50):134.3μmol/L at 24 h).The formulation exhibiting the highest toxicity at 48 h was 2 mmol/L AgNPs–liposomes against Caco-2 cells(IC_(50):4.6μmol/L).In contrast,BSA and PVP coatings significantly reduced toxicity,with IC_(50) of 2.2μmol/L for 50 mmol/L BSA–AgNPs and 14.9μmol/L for 50 mmol/L PVP–AgNPs in Caco-2 cells.Liposome-encapsulated AgNPs showed enhanced toxicity against square-shaped Caco-2 cells compared to fibroblast-like U251 cells(p<0.05),highlighting their potential for targeted cancer therapy.The findings of this study demonstrate that surface modifications and encapsulation strategies critically influence the biological effects of AgNPs in liposomes,providing a promising approach for enhanced anticancer activity.
