胃蛋白酶对CdS纳米粒子的表面修饰及分析应用

以巯基乙酸为稳定剂及表面修饰剂,在水溶液中合成了平均粒径为10 nm左右的CdS纳米粒子,用胃蛋白酶改变CdS纳米粒子的表面修饰状态并研究了其系列特性.CdS纳米粒子在292 nm附近有强的紫外吸收，有524.8 nm的荧光发射，胃蛋白酶对其表面修饰后，紫外吸收峰位不变，荧光峰位蓝移至462.4 nm,荧光强度降低.温度及pH值对表面修饰产生影响.在最佳实验条件下,胃蛋白酶质量浓度在2～20 mg/L范围内与荧光降低值之间成线性关系,检测限 (3σ) 为0.13　mg/L (n=10)，方法可用于人体胃液胃蛋白酶的测定.

Surface-Modification of CdS Nano-Particles by Using Pepsin and Its Analytical Application

CdS semiconductor nano-particles were synthesized in aqueous solution by using mercaptoethylic acid as the stabilizer as well as surface-modification reagent.The average size of CdS nano-particles estimated from TEM graph is ca.10 nm.The CdS nano-particles exhibited strong ultraviolet absorption at 292 nm and fluorescence emission at 524.8 nm.When surface-modification of CdS nano-particles were replaced with pepsin,ultraviolet absorption peak kept same,fluorescence emission intensity decreased as well as fluorescence peak shifted to 462.4nm.Temperature and pH value influenced surface-modification of CdS nano-particles.Under optimal conditions,a concentration of 2～20 mg/L of pepsin could be determined on the basis of fluorescence intensity decrease ratio of CdS nano-particles,with a detection limit 3σ of 0.13 mg/L (n=10).The proposed method was applied to the detection of the concentration of pepsin in human gastric juice.