The influence of different pH values between assembly and application environment on the surface properties of layer-by-layer assembled heparin and chitosan multilayer films was investigated.The high adsorption amount...The influence of different pH values between assembly and application environment on the surface properties of layer-by-layer assembled heparin and chitosan multilayer films was investigated.The high adsorption amount of cationic dye and high wettability on the chitosan terminated multilayer films at high environment pH may indicate the excess of free sulfate group existed on the chitosan surface.Since the ionization degree of chitosan decreased with increasing of pH,the multilayer films assembled at low pH will lead to some excess free unpaired sulfate group in higher pH application environment,which paired with ionized amino group under prepared conditions.The blood-compatibility tests performed with these films clearly demonstrated that the good anticoagulant activity of low pH assembled heparin/chitosan even on the chitosan-terminated surface.Such an easy and controlled processing by the difference of pH values between assembly and application environment may have a good potential for fabrication of biomedical device coating.展开更多
The deprotonation of an amphiphilic porphyrin, meso-tetra (p-hydroxylphenyl)porphyrin with a hexadecyl chain(THPPH2), has been observed by means of UV-Visspectroscopy in CTAB micellar solutions. With increasing of PH ...The deprotonation of an amphiphilic porphyrin, meso-tetra (p-hydroxylphenyl)porphyrin with a hexadecyl chain(THPPH2), has been observed by means of UV-Visspectroscopy in CTAB micellar solutions. With increasing of PH values, the Soret band shiftsfrom 424 nm to 441nm, and the four-Q bands (520 nm, 560 nm, 595nm, 655 nm) aredisappeared while two new Q-bands are appeared at 585 nm and 675 nm, which is similar tometal-porphyrin, means that the deprotonation of porphyrin takes place. Comparing withthe spectra in an other solutions, the spectral characteration of THPPH2 in neutral and inbasic CTAB solutions is similar to that in CHCI3 and basic aqueous solutions respectively,suggesting that the solubilizing location of THPPH2 takes a change from inner to the outer of theCTAB micellars with the PH value of solutions increasing between 6. 20 and 11. 19.展开更多
文摘The influence of different pH values between assembly and application environment on the surface properties of layer-by-layer assembled heparin and chitosan multilayer films was investigated.The high adsorption amount of cationic dye and high wettability on the chitosan terminated multilayer films at high environment pH may indicate the excess of free sulfate group existed on the chitosan surface.Since the ionization degree of chitosan decreased with increasing of pH,the multilayer films assembled at low pH will lead to some excess free unpaired sulfate group in higher pH application environment,which paired with ionized amino group under prepared conditions.The blood-compatibility tests performed with these films clearly demonstrated that the good anticoagulant activity of low pH assembled heparin/chitosan even on the chitosan-terminated surface.Such an easy and controlled processing by the difference of pH values between assembly and application environment may have a good potential for fabrication of biomedical device coating.
文摘The deprotonation of an amphiphilic porphyrin, meso-tetra (p-hydroxylphenyl)porphyrin with a hexadecyl chain(THPPH2), has been observed by means of UV-Visspectroscopy in CTAB micellar solutions. With increasing of PH values, the Soret band shiftsfrom 424 nm to 441nm, and the four-Q bands (520 nm, 560 nm, 595nm, 655 nm) aredisappeared while two new Q-bands are appeared at 585 nm and 675 nm, which is similar tometal-porphyrin, means that the deprotonation of porphyrin takes place. Comparing withthe spectra in an other solutions, the spectral characteration of THPPH2 in neutral and inbasic CTAB solutions is similar to that in CHCI3 and basic aqueous solutions respectively,suggesting that the solubilizing location of THPPH2 takes a change from inner to the outer of theCTAB micellars with the PH value of solutions increasing between 6. 20 and 11. 19.
