过氧化氢酶在琼脂糖膜中的电化学研究

用琼脂糖(Agarose)将过氧化氢酶(Cat)固定在热裂解石墨电极表面,制备了Cat-agarose膜修饰电极。包埋在琼脂糖中的过氧化氢酶可以与电极直接传递电子,在pH6．0的磷酸缓冲溶液中可得一对可逆的过氧化氢酶辅基血红素Fe(Ⅲ)／Fe(Ⅱ)氧化还原峰,式电势为-0．343V(vs．SCE)。其式电势随溶液的pH值增加而负移且呈线性关系,直线斜率为-36．8mV／pH,说明过氧化氢酶的电子传递过程伴随有质子的转移。紫外可见光谱、红外光谱表明,在琼脂糖膜中过氧化氢酶的构象保持不变。并研究了过氧化氢酶修饰电极对氧气、过氧化氢、一氧化氮的电催化性质。在16．5～278／μmol／L的范围内,催化电流与过氧化氢浓度呈线性关系;在2．75～20．76mmol／L的范围内,催化电流与亚硝酸根浓度呈线性关系。     

磺酰脲除草剂与过氧化氢酶的相互作用

应用荧光光谱法研究了水溶液中氯磺隆、甲磺隆、苄嘧磺隆与过氧化氢酶分子间的结合反应。结果表明,3种除草剂对过氧化氢酶的荧光均有较强的猝灭作用,且形成复合物所产生的静态猝灭是引起过氧化氢酶荧光猝灭的主要原因。进一步根据荧光猝灭结果确定了除草剂-酶复合物的形成常数和结合位点数。氯磺隆：K=8.69×105 L·mol-1, n=1.16;甲磺隆：K=1.01×106 L·mol-1, n=1.21;苄嘧磺隆：K=3.52×103 L·mol-1, n=0.77。由此可见,3种除草剂与过氧化氢酶的结合作用：甲磺隆＞氯磺隆＞苄嘧磺隆。     

Mussel-inspired chemistry in producing mechanically robust and bioactive hydrogels as skin dressings

The development of hydrogels as skin dressings demonstrates a great potential in real life applications. To achieve this, the hydrogel has to conquer its natural poor mechanical strength, and to prolong its lifetime, antifatigue and self-healing properties originating from dynamic interactions are also required. As skin dressings, the hydrogel needs to maintain its ductility while pursuing the above mentioned properties. In this work, poly(ethylene glycol) diacrylate is used to produce skin dressings by reinforcing poly(ethylene glycol) diacrylate/alginate double network hydrogels with a crosslinker from mussel-inspired chemistry, which is 3,4-dihydroxy-l-phenylalanine. This crosslinking methodology significantly improved mechanical strength of the hydrogel, with 11,200% increase in compressive failure strength; it endowed the hydrogel with outstanding antifatigue and training strengthening properties that makes its mechanical strength increasing in a 50 cycles compressive test; the hydrogel showed excellent self-healing properties that in rheological characterization; it also displayed enhanced storage modulus after withstanding a shear strain up to 1100%; meanwhile, the hydrogel exhibited extreme ductility with an elastic modulus of only 10.90–16.53 kPa. 3,4-dihydroxy-l-phenylalanine also renders the hydrogel its inherent antioxidant activity, conductivity, and bioadhesiveness. Together with the highly transparent appearance, the hydrogels possess a great potential and practibility in the fields of skin dressings.