The main compounds of off-odor volatiles from irradiated refrigerated vacuum-packaged pork were ana- lyzed by gas chromatograph/mass spectrometer (GC-MS).The analytical results showed that the main compounds of off-od...The main compounds of off-odor volatiles from irradiated refrigerated vacuum-packaged pork were ana- lyzed by gas chromatograph/mass spectrometer (GC-MS).The analytical results showed that the main compounds of off-odor volatiles were dimethyl disulfide,dimethyl sulfide,dimethyl trisulfide,S-methyl thioacetate,and methanethiol.It was proved that the off-odor volatile came from irradiated S-containing amino acid and thiamin.展开更多
Degradation of low-concentration p-nitrophenol(p-NP)aqueous solution was carried out in 254/185 nm photolysis.The effects of Mn^(2+),pH value,O_2 and O_3 on the degradation efficiency have been investigated.It was obs...Degradation of low-concentration p-nitrophenol(p-NP)aqueous solution was carried out in 254/185 nm photolysis.The effects of Mn^(2+),pH value,O_2 and O_3 on the degradation efficiency have been investigated.It was observed that the singlet oxygen scavenger Mn^(2+)did not affect the degradation of p-NP.In acidic and alkaline solutions,the degradation efficiency was enhanced in comparison to that in neutral solution.The presence of O_2 dramatically promoted the degradation of p-NP,while that of O_3 impeded it.展开更多
Photoinduced chemical reactions of 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF_6]) were studied by laser photolysis at a wavelength of 266 nm.Excited triplet state ~3[bmim]^+ was observed,radical cation...Photoinduced chemical reactions of 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF_6]) were studied by laser photolysis at a wavelength of 266 nm.Excited triplet state ~3[bmim]^+ was observed,radical cation [bmim]^(2+) and neutral [bmim] radical via photoionization were also formed.Energy transfer from ~3[bmim]^+ toβ-carotene was confirmed.Oxidation via one electron transfer from TMPD to ~3[bmim]^+ was also observed and the rate constant was determined to be 1.2×10.5 L.mol^(-1).s^(-1).The reaction of [bmim][PF_6] with hydrated electron (e_(aq)) was confirmed by laser photolysis in aqueous solution.展开更多
Reaction of p-tert-oxocalix[4]arene in acetonitrile (CH3CN) by 308nm laser pulses was investigated to understand its mechanism as polymer stabilizer. Four main absorption bands were observed at 300nm, 400nm, 460nm and...Reaction of p-tert-oxocalix[4]arene in acetonitrile (CH3CN) by 308nm laser pulses was investigated to understand its mechanism as polymer stabilizer. Four main absorption bands were observed at 300nm, 400nm, 460nm and 540nm. The 300nm absorption was assigned to the absorption of phenoxy radical, and the 460nm and 540nm were triple state absorption. It was concluded that the relative stable phenoxy radical mediate was formed through intramolecular energy transition of carbonyl triplet after laser excitation in CH3CN. The formation mechanism of phenoxyl radical was quite different from that in cyclohexane (C6H12), which was cooperation of two-photon process and one-photon process.展开更多
Due to the nontoxicity and efficient anti-cancer activity, more and more attention has been paid to N-glycoside compounds. Laser photolysis of N-(α-D-glucopyranoside) salicyloyl hydrazine (NGSH) has been performed fo...Due to the nontoxicity and efficient anti-cancer activity, more and more attention has been paid to N-glycoside compounds. Laser photolysis of N-(α-D-glucopyranoside) salicyloyl hydrazine (NGSH) has been performed for the first time. The research results show that NGSH has high photosensitivity and is vulnerable to be photo-ionized via a monophotonic process with a quantum yield of 0.02, generating NGSH+· and hydrated electrons. Under the aerobic condition of cells, the hydrated electrons are very easy to combine with oxygen to generate 1O2 and O2-, both of which are powerful oxidants that can kill the cancer cells. In addition, NGSH+· can be changed into neutral radicals by deprotonation with a pKa value of 4.02 and its decay constant was determined to be 2.55×109dm3·mol-1·s-1. NGSH also can be oxidized by SO4-. with a rate constant of 1.76×109 dm3·mol-1.s-1, which further confirms the results of photoionization. All of these results suggest that this new N-glycoside compound might be useful for cancer treatment.展开更多
Under the photocatalysis of 365 nm ultraviolet radiation,ultrafine TiO_(2)caused the oxidative damage of Teasy plasmid DNA.The damage was determined by gel-electrophoresis.Then,a different dose ofβ-CD was added to th...Under the photocatalysis of 365 nm ultraviolet radiation,ultrafine TiO_(2)caused the oxidative damage of Teasy plasmid DNA.The damage was determined by gel-electrophoresis.Then,a different dose ofβ-CD was added to the reaction,and the damage was restrained.The rate of damage restraining reached 97%when the mass ofβ-CD was 4 times as that of TiO_(2).Through UV scan and IR spectroscopy,it was found that the Ti-O of ultrafine TiO2 was bound with-OH ofβ-CD cavum and the-OH on the surface of ultrafine TiO2 disappeared,so the formation of?OH was controlled.The ultrafine TiO2 has been widely used,but it was determined to be carcinogenic by some research.The protection effect ofβ-CD to DNA in the molecular level takes a new look on the surface modification of nano particles to decrease the toxic effect.展开更多
One-pot synthesis of magnetic nanogels via photochemical method is reported in this paper. Poly(2-hydroxyethyl methacrylate)(PHEMA) magnetic nanogels are synthesized by in-situ polymeriza-tion of 2-hydroxyethyl methac...One-pot synthesis of magnetic nanogels via photochemical method is reported in this paper. Poly(2-hydroxyethyl methacrylate)(PHEMA) magnetic nanogels are synthesized by in-situ polymeriza-tion of 2-hydroxyethyl methacrylate(HEMA) and N,N'-methylene-bis-(acrylamide)(MBA) in Fe3O4 aqueous suspension under UV irradiation. The structure and compositions of magnetic nanogels are characterized by FTIR,TGA,SEM,TEM and PCS. TGA measurement indicates that magnetic nanogels contain 90% magnetite. Both naked Fe3O4 and magnetic nanogels are superparamagnatic at room temperature according to magnetization curves. The swollen capability of the hydrogel shell is proved by contrasting the particles sizes obtained by SEM,TEM and PCS. Particle diameters can be manipu-lated by changing monomer concentration and irradiation time. A mechanism of the coating process is proposed.展开更多
The impact of TiO2 nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied.The impact of TiO2 nanoparticles on DNA synthesis was investigated by adding TiO2 nanopart...The impact of TiO2 nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied.The impact of TiO2 nanoparticles on DNA synthesis was investigated by adding TiO2 nanoparticles in different sizes and at various concentrations into the polymerase chain reaction(PCR)system.TiO2 nanoparticles were premixed with the DNA polymerase,the primer or the template,respectively and then the supernatant and the precipitation of each mixture were added into the PCR system separately to observe the impact on DNA synthesis.Sequentially the interaction be-tween TiO2 nanoparticles and the DNA polymerase,the primer or the template was further analyzed by using UV-visible spectroscopy and polyacrylamide gel electrophoresis(PAGE).The results suggest that TiO2 nanoparticles inhibit DNA synthesis in the PCR system in the dark more severely than mi-croscale TiO2 particles at the equivalent concentration and the inhibition effect of TiO2 nanoparticles is concentration dependent.The molecular mechanism of such inhibition is that in the dark,TiO2 nanoparticles interact with the DNA polymerase through physical adsorption while TiO2 nanoparticles do with the primer or the template in a chemical adsorption manner.The disfunction levels of the bio-molecules under the impact of TiO2 nanoparticles are in the following order:the primer>the tem-plate>the DNA polymerase.展开更多
The photooxidation damage of lysozyme under 315-375 nm irradiation in the presence of riboflavin was studied by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE).Indica- tions showed that the m...The photooxidation damage of lysozyme under 315-375 nm irradiation in the presence of riboflavin was studied by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE).Indica- tions showed that the mechanisms and products of oxidative damage were relative to the concentra- tion of riboflavin,the time of irradiation and the ambience.The type I process was examined in a nitrogen saturated solution,whereas both type I and type II were observed in an aerobic atmosphere and type II was the dominant process.The study also suggested that antioxidants,such as melatonin, can reduce the damage of lysozyme effectively.展开更多
One-pot synthesis of magnetic nanogels with excellent biocompatibility via the photochemical method is reported in this paper.Poly(PEGMA) modified superparamagnetic nanogels(poly(PEGMA) magnetic nanogels) were synthes...One-pot synthesis of magnetic nanogels with excellent biocompatibility via the photochemical method is reported in this paper.Poly(PEGMA) modified superparamagnetic nanogels(poly(PEGMA) magnetic nanogels) were synthesized by in-situ polymerization using poly(ethylene glycol) methacrylate(PEGMA) as the monomer and N,N'-methylene-bis-(acrylamide)(MBA) as the cross-linking agent in magnetite aqueous suspension under UV irradiation.The surface functional groups and components of magnetic nanogels were analyzed by Fourier transform infrared spectroscopy(FTIR) and a thermogra-vimetric analyzer(TGA).The results indicated that the poly(PEGMA) magnetic nanogels were synthe-sized successfully by coating poly(PEGMA) on the Fe3O4 nanoparticles under UV irradiation,and the Fe3O4 nanoparticles content in this nanogels was above 50 wt%.The morphology,size,zeta-potential and magnetic property were also characterized.The magnetic nanogels had a nearly spherical shape and core-shell structure,the average size in aqueous system measured by photon correlation spec-troscopy(PCS) was 68.4 nm,which was much bigger than that in the dry state,the nanogels behaved superparamagnetically with saturated magnetization of 58.6 emu/g,and the zeta-potential was-16.3-_17.3 mV at physiological pH(6.8-7.4) which could help to maintain stability in blood.The preliminary application as drug carrier was made and the doxorubicin-loaded magnetic nanogels had an excellent property in slow-release.The experiment indicated that the magnetic nanogel was an ideal candidate carrier in target drug delivery systems and other biomedical application.展开更多
The reactions between gatifloxacin(GFX) and various one-electron oxidants,such as ˙OH,N3˙,Br2˙ˉ,and SO4˙ˉ,have been studied by pulse radiolysis techniques.The GFX radical anion formed in the reaction of GFX with...The reactions between gatifloxacin(GFX) and various one-electron oxidants,such as ˙OH,N3˙,Br2˙ˉ,and SO4˙ˉ,have been studied by pulse radiolysis techniques.The GFX radical anion formed in the reaction of GFX with eaqˉ could either be protonated or deprotonated,and the absorption of GFX radical anion was located at 390 nm.The transient species produced by the reaction of GFX with ˙OH radical shows a broad band in the 380?600 nm region with a shoulder,while the oxidation by N3˙,SO4˙ˉ,and Br2˙ˉ results in an absorption band with λmax = 370 nm.At neutral condition(pH 7),the rate constants of GFX reacting with ˙OH,N3˙,Br2˙ˉ,SO4˙ˉ and eaqˉ are estimated to be 1.0 × 1010,3.1 × 109,2.8 × 109,3.0 × 109,and 1.8 × 1010 dm3 mol?1 s?1,respectively.From the pH dependence on the formation of electron adducts and on the rate constant of GFX with eaqˉ,the pKa of GFX radical anion is estimated to be 5.5 and 9.3.展开更多
The properties of norfloxacin(NFX)and its 4?-N-acetyl derivative(ANFX)are investigated in different pH aqueous solutions and H2O-CH3CN mixed solutions,to determine the effects of pH and polarity on their ground and ex...The properties of norfloxacin(NFX)and its 4?-N-acetyl derivative(ANFX)are investigated in different pH aqueous solutions and H2O-CH3CN mixed solutions,to determine the effects of pH and polarity on their ground and excited states.The triplet states of NFX and ANFX are affected more by pH than by polarity.The pH dependence of the NFX and ANFX triplet states is likely due to the different quantum yields of different protonated forms.Steady-state fluorescence,time-resolved fluorescence,and laser flash photolysis experiments at different pH values provide clear evidence of the involvement of different intramolecular charge-transfer pathways in the singlet states of NFX and ANFX.The different electron-donating capacities of 1-N,1?-N,and 4?-N under different conditions determine the major pathway.展开更多
To study the molecular mechanism of high mutation frequency induced by high-energy-pulse-electron (HEPE) beam radiation, the effects of HEPE radiation on yeast cells, plasma membrane, plasmid DNA, and protein activity...To study the molecular mechanism of high mutation frequency induced by high-energy-pulse-electron (HEPE) beam radiation, the effects of HEPE radiation on yeast cells, plasma membrane, plasmid DNA, and protein activity were investigated by means of cell counting, gel electrophoresis, AO/EB double fluorescent staining, etc. The results showed that the viability of yeast cells declined statistically with increase of absorbed doses. The half lethal dose (LD50) was 134 Gy. HEPE beam radiation had little influence on the function of plasma membrane and protein, while it could induce much DNA damage of single strand breaks (SSB) and double strand breaks (DSB) that were required for gene mutation. The G-value for DSB formation of HEPE beam radiation in aqueous solution was 5.7 times higher than that caused by 60Co gamma rays. HEPE can be a new effective method for induced mutation breeding and deserves further research in the future.展开更多
The electron transfer reaction of triplet menadione(3MQ?)with polyguanylic acid(polyG)in CH3CN rich(97%)solution was investigated by 248 nm(KrF)laser flash photolysis.The transient absorption spectra and kinetics obta...The electron transfer reaction of triplet menadione(3MQ?)with polyguanylic acid(polyG)in CH3CN rich(97%)solution was investigated by 248 nm(KrF)laser flash photolysis.The transient absorption spectra and kinetics obtained from the interaction of 3MQ?with polyG demonstrated that the primary radical ion pair,radical cation of polyG and radical anion of me-nadione can be detected simultaneously.The results demonstrated that the reaction rate con-stant of 3MQ?with polyG is almost equal to that of 3MQ?with dGMP.展开更多
The photo-physical and photo-chemical properties of melatonin(ML)werestudied by 266 nm laser flash photolysis(LFP).ML undergoes photo-ionization to produce radicalcation of ML(ML^(·+))and hydrated electrons(e_(aq...The photo-physical and photo-chemical properties of melatonin(ML)werestudied by 266 nm laser flash photolysis(LFP).ML undergoes photo-ionization to produce radicalcation of ML(ML^(·+))and hydrated electrons(e_(aq)^-),while excited triplet state~3ML~*is alsoformed during photolysis.The oxidation via one electron transfer from ML to SO_4^(·+)and thetriplet state of riboflavin(~3RF~*)has been also investigated and the rate constants for theprocess have been determined to be 8.0x10^9 and 1.4x10^9 L·mol^(-1)·s^(-1)respectively.Theradical cation of 2,2''-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS^(·+))scavengingcapacities of melatonin and other antioxidants are compared in this paper.展开更多
Scavenging of hydroxyl radical (·OH) by phycobiliproteins (C-phycocyanin, Allophyco- cyanin and R-phycoerythrin) was studied by competitive kinetics methods. Hydroxyl radicals were generated from pulse radiolysis...Scavenging of hydroxyl radical (·OH) by phycobiliproteins (C-phycocyanin, Allophyco- cyanin and R-phycoerythrin) was studied by competitive kinetics methods. Hydroxyl radicals were generated from pulse radiolysis of aqueous systems saturated with nitrous oxide (N2O). The experimental results indicated that the three types of phycobiliproteins are all strong scavengers of· OH, the rate constants are around (2.8-5.6)×109 L·2 mol1 · s 1.展开更多
The piperonal electron affinity was studied using pulse radiolysis technique.The electron transfer reaction process between piperonal and anthraquinone-2-sulfate was observed in the pH 7 phosphoric acid salt buffer.Th...The piperonal electron affinity was studied using pulse radiolysis technique.The electron transfer reaction process between piperonal and anthraquinone-2-sulfate was observed in the pH 7 phosphoric acid salt buffer.The transient absorption spectra of electron transfer re-action between piperonal and anthraquinone-2-sulfate were obtained,and the initial proof of the electron transfer between electron donor and acceptor was provided directly.The one-electron reduction potential of piperonal was determined to be?0.457 V.展开更多
基金Supported by National Natural Science Foundation of China(10475025).
文摘The main compounds of off-odor volatiles from irradiated refrigerated vacuum-packaged pork were ana- lyzed by gas chromatograph/mass spectrometer (GC-MS).The analytical results showed that the main compounds of off-odor volatiles were dimethyl disulfide,dimethyl sulfide,dimethyl trisulfide,S-methyl thioacetate,and methanethiol.It was proved that the off-odor volatile came from irradiated S-containing amino acid and thiamin.
文摘Degradation of low-concentration p-nitrophenol(p-NP)aqueous solution was carried out in 254/185 nm photolysis.The effects of Mn^(2+),pH value,O_2 and O_3 on the degradation efficiency have been investigated.It was observed that the singlet oxygen scavenger Mn^(2+)did not affect the degradation of p-NP.In acidic and alkaline solutions,the degradation efficiency was enhanced in comparison to that in neutral solution.The presence of O_2 dramatically promoted the degradation of p-NP,while that of O_3 impeded it.
基金Supported by National Natural Science Foundation of China(20573130,20673137)
文摘Photoinduced chemical reactions of 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF_6]) were studied by laser photolysis at a wavelength of 266 nm.Excited triplet state ~3[bmim]^+ was observed,radical cation [bmim]^(2+) and neutral [bmim] radical via photoionization were also formed.Energy transfer from ~3[bmim]^+ toβ-carotene was confirmed.Oxidation via one electron transfer from TMPD to ~3[bmim]^+ was also observed and the rate constant was determined to be 1.2×10.5 L.mol^(-1).s^(-1).The reaction of [bmim][PF_6] with hydrated electron (e_(aq)) was confirmed by laser photolysis in aqueous solution.
基金National Natural Science Foundation of China (No.29602005)Director’s Funds of CAEP (No.42105040407 and No.62601080311)
文摘Reaction of p-tert-oxocalix[4]arene in acetonitrile (CH3CN) by 308nm laser pulses was investigated to understand its mechanism as polymer stabilizer. Four main absorption bands were observed at 300nm, 400nm, 460nm and 540nm. The 300nm absorption was assigned to the absorption of phenoxy radical, and the 460nm and 540nm were triple state absorption. It was concluded that the relative stable phenoxy radical mediate was formed through intramolecular energy transition of carbonyl triplet after laser excitation in CH3CN. The formation mechanism of phenoxyl radical was quite different from that in cyclohexane (C6H12), which was cooperation of two-photon process and one-photon process.
基金the National Natural Science Foundation of China (Grant Nos. 30570376 and 50673078)Shanghai Project (Grant Nos. 06JC14068 and 08ZZ21)
文摘Due to the nontoxicity and efficient anti-cancer activity, more and more attention has been paid to N-glycoside compounds. Laser photolysis of N-(α-D-glucopyranoside) salicyloyl hydrazine (NGSH) has been performed for the first time. The research results show that NGSH has high photosensitivity and is vulnerable to be photo-ionized via a monophotonic process with a quantum yield of 0.02, generating NGSH+· and hydrated electrons. Under the aerobic condition of cells, the hydrated electrons are very easy to combine with oxygen to generate 1O2 and O2-, both of which are powerful oxidants that can kill the cancer cells. In addition, NGSH+· can be changed into neutral radicals by deprotonation with a pKa value of 4.02 and its decay constant was determined to be 2.55×109dm3·mol-1·s-1. NGSH also can be oxidized by SO4-. with a rate constant of 1.76×109 dm3·mol-1.s-1, which further confirms the results of photoionization. All of these results suggest that this new N-glycoside compound might be useful for cancer treatment.
基金Supported by the National Natural Science Foundation of China(Grant No.50572074)Shanghai Special Fund for Nano Materials(05nm05028).
文摘Under the photocatalysis of 365 nm ultraviolet radiation,ultrafine TiO_(2)caused the oxidative damage of Teasy plasmid DNA.The damage was determined by gel-electrophoresis.Then,a different dose ofβ-CD was added to the reaction,and the damage was restrained.The rate of damage restraining reached 97%when the mass ofβ-CD was 4 times as that of TiO_(2).Through UV scan and IR spectroscopy,it was found that the Ti-O of ultrafine TiO2 was bound with-OH ofβ-CD cavum and the-OH on the surface of ultrafine TiO2 disappeared,so the formation of?OH was controlled.The ultrafine TiO2 has been widely used,but it was determined to be carcinogenic by some research.The protection effect ofβ-CD to DNA in the molecular level takes a new look on the surface modification of nano particles to decrease the toxic effect.
基金Supported by the Shanghai Municipal Commission for Special Project of Nanometer Science and Technology (Grant No. 0452nm068)
文摘One-pot synthesis of magnetic nanogels via photochemical method is reported in this paper. Poly(2-hydroxyethyl methacrylate)(PHEMA) magnetic nanogels are synthesized by in-situ polymeriza-tion of 2-hydroxyethyl methacrylate(HEMA) and N,N'-methylene-bis-(acrylamide)(MBA) in Fe3O4 aqueous suspension under UV irradiation. The structure and compositions of magnetic nanogels are characterized by FTIR,TGA,SEM,TEM and PCS. TGA measurement indicates that magnetic nanogels contain 90% magnetite. Both naked Fe3O4 and magnetic nanogels are superparamagnatic at room temperature according to magnetization curves. The swollen capability of the hydrogel shell is proved by contrasting the particles sizes obtained by SEM,TEM and PCS. Particle diameters can be manipu-lated by changing monomer concentration and irradiation time. A mechanism of the coating process is proposed.
基金Supported by the National Natural Science Foundation of China(Grant Nos.50572074&50673078)the Shanghai Key Fundamental Project(Grant No.06JC14068)the Innovation Program of Shanghai Municipal Education Commis-sion(Grant No.08ZZ21)
文摘The impact of TiO2 nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied.The impact of TiO2 nanoparticles on DNA synthesis was investigated by adding TiO2 nanoparticles in different sizes and at various concentrations into the polymerase chain reaction(PCR)system.TiO2 nanoparticles were premixed with the DNA polymerase,the primer or the template,respectively and then the supernatant and the precipitation of each mixture were added into the PCR system separately to observe the impact on DNA synthesis.Sequentially the interaction be-tween TiO2 nanoparticles and the DNA polymerase,the primer or the template was further analyzed by using UV-visible spectroscopy and polyacrylamide gel electrophoresis(PAGE).The results suggest that TiO2 nanoparticles inhibit DNA synthesis in the PCR system in the dark more severely than mi-croscale TiO2 particles at the equivalent concentration and the inhibition effect of TiO2 nanoparticles is concentration dependent.The molecular mechanism of such inhibition is that in the dark,TiO2 nanoparticles interact with the DNA polymerase through physical adsorption while TiO2 nanoparticles do with the primer or the template in a chemical adsorption manner.The disfunction levels of the bio-molecules under the impact of TiO2 nanoparticles are in the following order:the primer>the tem-plate>the DNA polymerase.
基金the National Natural Science Foundation of China(Grant Nos.20373086 and 10574134)the research program of the Chinese Academy ofSciences
文摘The photooxidation damage of lysozyme under 315-375 nm irradiation in the presence of riboflavin was studied by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE).Indica- tions showed that the mechanisms and products of oxidative damage were relative to the concentra- tion of riboflavin,the time of irradiation and the ambience.The type I process was examined in a nitrogen saturated solution,whereas both type I and type II were observed in an aerobic atmosphere and type II was the dominant process.The study also suggested that antioxidants,such as melatonin, can reduce the damage of lysozyme effectively.
基金Supported by the Natural Science Foundation of Shandong Province (Grant No. Q2006F01)Scientific and Technological Project of Shandong Province (Grant No. 2007GG3WZ02066)+1 种基金Scientific and Technological Project of Department of Education, Shandong (Grant No. J07WC01)supported by the Key Laboratory of Bio-physics of Shandong Province
文摘One-pot synthesis of magnetic nanogels with excellent biocompatibility via the photochemical method is reported in this paper.Poly(PEGMA) modified superparamagnetic nanogels(poly(PEGMA) magnetic nanogels) were synthesized by in-situ polymerization using poly(ethylene glycol) methacrylate(PEGMA) as the monomer and N,N'-methylene-bis-(acrylamide)(MBA) as the cross-linking agent in magnetite aqueous suspension under UV irradiation.The surface functional groups and components of magnetic nanogels were analyzed by Fourier transform infrared spectroscopy(FTIR) and a thermogra-vimetric analyzer(TGA).The results indicated that the poly(PEGMA) magnetic nanogels were synthe-sized successfully by coating poly(PEGMA) on the Fe3O4 nanoparticles under UV irradiation,and the Fe3O4 nanoparticles content in this nanogels was above 50 wt%.The morphology,size,zeta-potential and magnetic property were also characterized.The magnetic nanogels had a nearly spherical shape and core-shell structure,the average size in aqueous system measured by photon correlation spec-troscopy(PCS) was 68.4 nm,which was much bigger than that in the dry state,the nanogels behaved superparamagnetically with saturated magnetization of 58.6 emu/g,and the zeta-potential was-16.3-_17.3 mV at physiological pH(6.8-7.4) which could help to maintain stability in blood.The preliminary application as drug carrier was made and the doxorubicin-loaded magnetic nanogels had an excellent property in slow-release.The experiment indicated that the magnetic nanogel was an ideal candidate carrier in target drug delivery systems and other biomedical application.
基金supported by the National Natural Science Foundation of China (21173252)
文摘The reactions between gatifloxacin(GFX) and various one-electron oxidants,such as ˙OH,N3˙,Br2˙ˉ,and SO4˙ˉ,have been studied by pulse radiolysis techniques.The GFX radical anion formed in the reaction of GFX with eaqˉ could either be protonated or deprotonated,and the absorption of GFX radical anion was located at 390 nm.The transient species produced by the reaction of GFX with ˙OH radical shows a broad band in the 380?600 nm region with a shoulder,while the oxidation by N3˙,SO4˙ˉ,and Br2˙ˉ results in an absorption band with λmax = 370 nm.At neutral condition(pH 7),the rate constants of GFX reacting with ˙OH,N3˙,Br2˙ˉ,SO4˙ˉ and eaqˉ are estimated to be 1.0 × 1010,3.1 × 109,2.8 × 109,3.0 × 109,and 1.8 × 1010 dm3 mol?1 s?1,respectively.From the pH dependence on the formation of electron adducts and on the rate constant of GFX with eaqˉ,the pKa of GFX radical anion is estimated to be 5.5 and 9.3.
基金supported by the National Natural Science Foundation of China(10675158)
文摘The properties of norfloxacin(NFX)and its 4?-N-acetyl derivative(ANFX)are investigated in different pH aqueous solutions and H2O-CH3CN mixed solutions,to determine the effects of pH and polarity on their ground and excited states.The triplet states of NFX and ANFX are affected more by pH than by polarity.The pH dependence of the NFX and ANFX triplet states is likely due to the different quantum yields of different protonated forms.Steady-state fluorescence,time-resolved fluorescence,and laser flash photolysis experiments at different pH values provide clear evidence of the involvement of different intramolecular charge-transfer pathways in the singlet states of NFX and ANFX.The different electron-donating capacities of 1-N,1?-N,and 4?-N under different conditions determine the major pathway.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 30570376 and 50673078)the Shanghai Key Fundamental Project (Grant No. 06JC14068)the Innovation Program of Shanghai Municipal Education Commis-sion (Grant No. 08ZZ21)
文摘To study the molecular mechanism of high mutation frequency induced by high-energy-pulse-electron (HEPE) beam radiation, the effects of HEPE radiation on yeast cells, plasma membrane, plasmid DNA, and protein activity were investigated by means of cell counting, gel electrophoresis, AO/EB double fluorescent staining, etc. The results showed that the viability of yeast cells declined statistically with increase of absorbed doses. The half lethal dose (LD50) was 134 Gy. HEPE beam radiation had little influence on the function of plasma membrane and protein, while it could induce much DNA damage of single strand breaks (SSB) and double strand breaks (DSB) that were required for gene mutation. The G-value for DSB formation of HEPE beam radiation in aqueous solution was 5.7 times higher than that caused by 60Co gamma rays. HEPE can be a new effective method for induced mutation breeding and deserves further research in the future.
基金the National Natural Science Foundat ion of China(Grant Nos.20133020&39830090)the Photo Science&Technology Research Foundat ion of Science and Technology Committee of Shanghai.
文摘The electron transfer reaction of triplet menadione(3MQ?)with polyguanylic acid(polyG)in CH3CN rich(97%)solution was investigated by 248 nm(KrF)laser flash photolysis.The transient absorption spectra and kinetics obtained from the interaction of 3MQ?with polyG demonstrated that the primary radical ion pair,radical cation of polyG and radical anion of me-nadione can be detected simultaneously.The results demonstrated that the reaction rate con-stant of 3MQ?with polyG is almost equal to that of 3MQ?with dGMP.
基金This work was supported by the National Natural Science Foundation of China(Grant No.20373086).
文摘The photo-physical and photo-chemical properties of melatonin(ML)werestudied by 266 nm laser flash photolysis(LFP).ML undergoes photo-ionization to produce radicalcation of ML(ML^(·+))and hydrated electrons(e_(aq)^-),while excited triplet state~3ML~*is alsoformed during photolysis.The oxidation via one electron transfer from ML to SO_4^(·+)and thetriplet state of riboflavin(~3RF~*)has been also investigated and the rate constants for theprocess have been determined to be 8.0x10^9 and 1.4x10^9 L·mol^(-1)·s^(-1)respectively.Theradical cation of 2,2''-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS^(·+))scavengingcapacities of melatonin and other antioxidants are compared in this paper.
文摘Scavenging of hydroxyl radical (·OH) by phycobiliproteins (C-phycocyanin, Allophyco- cyanin and R-phycoerythrin) was studied by competitive kinetics methods. Hydroxyl radicals were generated from pulse radiolysis of aqueous systems saturated with nitrous oxide (N2O). The experimental results indicated that the three types of phycobiliproteins are all strong scavengers of· OH, the rate constants are around (2.8-5.6)×109 L·2 mol1 · s 1.
基金supported by the National Natural Science Foundation of China(Grant No.30100035)Natural Science Foundation of Fujian(Grant No.C0510029).
文摘The piperonal electron affinity was studied using pulse radiolysis technique.The electron transfer reaction process between piperonal and anthraquinone-2-sulfate was observed in the pH 7 phosphoric acid salt buffer.The transient absorption spectra of electron transfer re-action between piperonal and anthraquinone-2-sulfate were obtained,and the initial proof of the electron transfer between electron donor and acceptor was provided directly.The one-electron reduction potential of piperonal was determined to be?0.457 V.
