Zhuo Cai-Xia, Wang Li-Hui, Feng Jing-Jing, Zhang Yao-Dong
Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China.
Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China.
Sensors (Basel). 2016 Nov 9;16(11):1477. doi: 10.3390/s16111477.
Trypsin is important during the regulation of pancreatic exocrine function. The detection of trypsin activity is currently limited because of the need for the substrate to be labeled with a fluorescent tag. A label-free fluorescent method has been developed to monitor trypsin activity. The designed peptide probe consists of six arginine molecules and a cysteine terminus and can be conjugated to DNA-stabilized silver nanoclusters (DNA-AgNCs) by Ag-S bonding to enhance fluorescence. The peptide probe can also be adsorbed to the surface of graphene oxide (GO), thus resulting in the fluorescence quenching of DNA-AgNCs-peptide conjugate because of Förster resonance energy transfer. Once trypsin had degraded the peptide probe into amino acid residues, the DNA-AgNCs were released from the surface of GO, and the enhanced fluorescence of DNA-AgNCs was restored. Trypsin can be determined with a linear range of 0.0-50.0 ng/mL with a concentration as low as 1 ng/mL. This label-free method is simple and sensitive and has been successfully used for the determination of trypsin in serum. The method can also be modified to detect other proteases.
胰蛋白酶在胰腺外分泌功能的调节过程中起着重要作用。目前，由于需要用荧光标签标记底物，胰蛋白酶活性的检测受到限制。一种无标记荧光方法已被开发用于监测胰蛋白酶活性。所设计的肽探针由六个精氨酸分子和一个半胱氨酸末端组成，可通过Ag-S键与DNA稳定的银纳米簇（DNA-AgNCs）结合以增强荧光。该肽探针也可吸附到氧化石墨烯（GO）表面，由于Förster共振能量转移，导致DNA-AgNCs-肽缀合物的荧光猝灭。一旦胰蛋白酶将肽探针降解为氨基酸残基，DNA-AgNCs就会从GO表面释放出来，DNA-AgNCs增强的荧光得以恢复。胰蛋白酶的测定线性范围为0.0 - 50.0 ng/mL，最低检测浓度为1 ng/mL。这种无标记方法简单且灵敏，已成功用于血清中胰蛋白酶的测定。该方法也可进行改进以检测其他蛋白酶。
