胃蛋白酶对CdTe纳米粒子的表面修饰及分析应用

以巯基乙酸为稳定剂和表面修饰剂, 在有机相中合成了平均粒径为3 nm左右的CdTe纳米粒子, 用胃蛋白酶改变纳米粒子的表面修饰状态并研究其系列特性. CdTe纳米粒子在320 nm处有强的紫外吸收, 在524.8 nm处有荧光发射. 经胃蛋白酶对其表面修饰后, 紫外吸收峰位不变, 但吸光强度升高, 荧光峰位蓝移至467.2 nm, 荧光强度降低. 温度、pH值及离子强度均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4—40 mg/L范围内与荧光降低值之间呈线性关系, 检测限(3σ)为0.28 mg/L(n=10), 该方法已被用于人体胃液胃蛋白酶的测定.

Surface-modification of CdTe Nano-particles by Pepsin and Its Analytical Application

CdTe semiconductor nano-particles were synthesized with mercaptoethylic acid as the stabilizer as well as surface-modification reagent. The average size of CdTe nano-particles estimated from TEM graph was ca. 3 nm. The CdTe nano-particles exhibited a strong ultraviolet absorption at 320 nm and fluorescence emission at 524.8 nm, respectively. When surface-modification of CdTe nano-particles were replaced with pepsin, ultraviolet absorption peak kept the same, absorption intensity at 320 nm increased. It can be observed that the fluorescence emission intensity decreased as well as the fluorescence peak shifted to 467.2 nm. Temperature, ion strength and pH value influenced the surface-modification of CdTe nano-particles. Under the optimal conditions, a mass concentration of pepsin in the range of 4—40 mg/L shows a linear relationship with the fluorescence intensity decreasing value of CdTe nano-particles, with a detection limit 3σ of 0.28 mg/L(n=10). The proposed method was applied to detection of the concentration of pepsin in human gastric juice.