A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing.The necessity for its sophistication arises from the availability of multi-dimensional s...A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing.The necessity for its sophistication arises from the availability of multi-dimensional sensing signals.Simultaneous monitoring of the redox current and color change synchronized with the oxidation state change significantly enhances sen-sitivity and selectivity.This study aimed to elucidate the modification of an indium tin oxide(ITO)electrode with a viologen monolayer with an ordered orientation.Novel methods were developed to immobilize a viologen molecule bearing a car-boxyl group to form assembled monolayers through a condensation reaction using 1-ethyl-3-(3-dimethylaminopropyl)-car-bodiimide with N-hydroxy-succinimide(EDC/NHS).In the two methods of immobilization,one utilizes a two-step process to firstly form an aromatic siloxane base layer and subsequently attach the viologen derivative through an amide linkage by post-amidation.The other employs a direct ester linkage between the hydroxyl groups of the ITO surface and the car-boxyl group of the viologen derivative.The latter method was also applied to immobilize a ferrocenyl group at a very short distance from the ITO surface.Potential-modulated UV-visible transmission absorption spectral measurement techniques with oblique incidence of plane-polarized light were employed to determine the orientation of the longitudinal axis of the reduced form of the viologen.The frequency dependence data of the potential-modulated transmission absorption signals were utilized to analyze the electron transfer kinetics.The performance of the two viologen-modified electrodes was com-pared to that of an ITO modified by post-amidation to the most commonly used base layer prepared with 3-aminopropyl triethoxysilane.展开更多
The aim of the present study was to compare one-step method to EDC/NHS crosslinking （EDC/NHS group） and one-step simultaneous method to EDC/NHS crosslinking and heparin immobilization （EDC/NHS- Heparin group） in i...The aim of the present study was to compare one-step method to EDC/NHS crosslinking （EDC/NHS group） and one-step simultaneous method to EDC/NHS crosslinking and heparin immobilization （EDC/NHS- Heparin group） in improving physiochemical and biological properties of native collagen sponge （Control group）. Modified collagen sponge overcome the disadvantages of native collagen sponge. IR spectra suggest the change of the functional groups. DSC data indicate that the stability of caloric transformation in EDC/NHS group is slightly higher than that of EDC/NHS-Heparin group. The crosslinking degree, stability against enzymes, stability in morphologically and biomechanical properties of EDC/NHS-Heparin group are higher than those of EDC/NHS group, whereas, the water-binding capacity in EDC/NHS-Heparin group is lower than that of EDC/NHS group. HUVECs in EDC/NHS-Heparin group scaffold proliferate fast, migrate well and distribute uniformly. One-step simultaneous method gains the better effects in above aspects, heparinized collagen matrices increase in angiogenic potential and suit for defect repairing and tissue engineering.展开更多
Tissue engineering response may be tailored via controlled,sustained release of active agents from protein-loaded degradable microparticles incorporated directly within three-dimensional(3D)ice-templated collagen scaf...Tissue engineering response may be tailored via controlled,sustained release of active agents from protein-loaded degradable microparticles incorporated directly within three-dimensional(3D)ice-templated collagen scaffolds.However,the effects of covalent crosslinking during scaffold preparation on the availability and release of protein from the incorporated microparticles have not been explored.Here,we load 3D ice-templated collagen scaffolds with controlled additions of poly-(DL-lactide-co-glycolide)microparticles.We probe the effects of subsequent N-(3-dimethylaminopropyl)-N0-ethylcarbodiimide hydrochloride crosslinking on protein release,using microparticles with different internal protein distributions.Fluorescein isothiocyanate labelled bovine serum albumin is used as a model protein drug.The scaffolds display a homogeneous microparticle distribution,and a reduction in pore size and percolation diameter with increased microparticle addition,although these values did not fall below those reported as necessary for cell invasion.The protein distribution within the microparticles,near the surface or more deeply located within the microparticles,was important in determining the release profile and effect of crosslinking,as the surface was affected by the carbodiimide crosslinking reaction applied to the scaffold.Crosslinking of microparticles with a high proportion of protein at the surface caused both a reduction and delay in protein release.Protein located within the bulk of the microparticles,was protected from the crosslinking reaction and no delay in the overall release profile was seen.展开更多
基金supports by the Grant-in-Aid of Scientific Research of Challenging Research(Exploratory)(JP23K17738)to TS from MEXT of Japanthe 41st grant of research from Nippon Sheet Glass Foundation for Materials Science and Engineering to TS.
文摘A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing.The necessity for its sophistication arises from the availability of multi-dimensional sensing signals.Simultaneous monitoring of the redox current and color change synchronized with the oxidation state change significantly enhances sen-sitivity and selectivity.This study aimed to elucidate the modification of an indium tin oxide(ITO)electrode with a viologen monolayer with an ordered orientation.Novel methods were developed to immobilize a viologen molecule bearing a car-boxyl group to form assembled monolayers through a condensation reaction using 1-ethyl-3-(3-dimethylaminopropyl)-car-bodiimide with N-hydroxy-succinimide(EDC/NHS).In the two methods of immobilization,one utilizes a two-step process to firstly form an aromatic siloxane base layer and subsequently attach the viologen derivative through an amide linkage by post-amidation.The other employs a direct ester linkage between the hydroxyl groups of the ITO surface and the car-boxyl group of the viologen derivative.The latter method was also applied to immobilize a ferrocenyl group at a very short distance from the ITO surface.Potential-modulated UV-visible transmission absorption spectral measurement techniques with oblique incidence of plane-polarized light were employed to determine the orientation of the longitudinal axis of the reduced form of the viologen.The frequency dependence data of the potential-modulated transmission absorption signals were utilized to analyze the electron transfer kinetics.The performance of the two viologen-modified electrodes was com-pared to that of an ITO modified by post-amidation to the most commonly used base layer prepared with 3-aminopropyl triethoxysilane.
基金Funded by the National Natural Science Foundation of China (10832012)the Natural Science Foudation of Tianjin city(08JCYBJC03400)
文摘The aim of the present study was to compare one-step method to EDC/NHS crosslinking （EDC/NHS group） and one-step simultaneous method to EDC/NHS crosslinking and heparin immobilization （EDC/NHS- Heparin group） in improving physiochemical and biological properties of native collagen sponge （Control group）. Modified collagen sponge overcome the disadvantages of native collagen sponge. IR spectra suggest the change of the functional groups. DSC data indicate that the stability of caloric transformation in EDC/NHS group is slightly higher than that of EDC/NHS-Heparin group. The crosslinking degree, stability against enzymes, stability in morphologically and biomechanical properties of EDC/NHS-Heparin group are higher than those of EDC/NHS group, whereas, the water-binding capacity in EDC/NHS-Heparin group is lower than that of EDC/NHS group. HUVECs in EDC/NHS-Heparin group scaffold proliferate fast, migrate well and distribute uniformly. One-step simultaneous method gains the better effects in above aspects, heparinized collagen matrices increase in angiogenic potential and suit for defect repairing and tissue engineering.
基金the European Research Council[ERC Advanced Grant 3205983D-E]the Medical Research Council,Arthritis Research UK,Reumafonds and the UKRMP。
文摘Tissue engineering response may be tailored via controlled,sustained release of active agents from protein-loaded degradable microparticles incorporated directly within three-dimensional(3D)ice-templated collagen scaffolds.However,the effects of covalent crosslinking during scaffold preparation on the availability and release of protein from the incorporated microparticles have not been explored.Here,we load 3D ice-templated collagen scaffolds with controlled additions of poly-(DL-lactide-co-glycolide)microparticles.We probe the effects of subsequent N-(3-dimethylaminopropyl)-N0-ethylcarbodiimide hydrochloride crosslinking on protein release,using microparticles with different internal protein distributions.Fluorescein isothiocyanate labelled bovine serum albumin is used as a model protein drug.The scaffolds display a homogeneous microparticle distribution,and a reduction in pore size and percolation diameter with increased microparticle addition,although these values did not fall below those reported as necessary for cell invasion.The protein distribution within the microparticles,near the surface or more deeply located within the microparticles,was important in determining the release profile and effect of crosslinking,as the surface was affected by the carbodiimide crosslinking reaction applied to the scaffold.Crosslinking of microparticles with a high proportion of protein at the surface caused both a reduction and delay in protein release.Protein located within the bulk of the microparticles,was protected from the crosslinking reaction and no delay in the overall release profile was seen.
