Xia Ning, Wang Xin, Wang Xiaojin, Zhou Binbin
Henan Province of Key Laboratory of New Optoelectronic Functional Materials, College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang 455000, Henan, China.
Materials (Basel). 2016 Oct 21;9(10):857. doi: 10.3390/ma9100857.
We presented the colorimetric and electrochemical methods for determination of the dipeptidyl peptidase-IV (DPP-IV) activity and screening of its inhibitor using gold nanoparticle (AuNP) as the probe. In the colorimetric assay, the substrate peptide with a sequence of Arg-Pro-Arg induced the aggregation and color change of AuNPs, whereas cleavage of the peptide by DPP-IV prevented the aggregation of AuNPs. Furthermore, the aggregation of AuNPs in the solution was easily initiated on a solid/liquid (electrode/electrolyte) surface, which induced a decrease in the electron-transfer resistance. However, once the peptide was clipped by DPP-IV, the assembly of AuNPs on electrode surface was prevented. Consequently, a higher electron-transfer resistance was observed. The colorimetric and electrochemical assays allowed for the determination of DPP-IV with the detection limits of 70 μU/mL and 0.55 μU/mL, respectively. Meanwhile, the proposed methods were used to determine DPP-IV inhibitor with satisfactory results. Both the colorimetric and electrochemical methods are simple, rapid and sufficiently sensitive for DPP-IV activity assay and inhibitor screening. The results also demonstrated that the AuNP-based colorimetric assay could be converted into an enhanced surface tethered electrochemical assay with improving sensitivity. The simple detection principle may be extended to the design of other peptidases biosensors with easy manipulation procedures.
我们展示了以金纳米颗粒（AuNP）为探针测定二肽基肽酶-IV（DPP-IV）活性及其抑制剂筛选的比色法和电化学方法。在比色测定中，序列为Arg-Pro-Arg的底物肽诱导AuNPs聚集并发生颜色变化，而DPP-IV对该肽的切割则阻止了AuNPs的聚集。此外，溶液中AuNPs的聚集很容易在固/液（电极/电解质）表面引发，这导致电子转移电阻降低。然而，一旦肽被DPP-IV切割，AuNPs在电极表面的组装就会被阻止。因此，观察到更高的电子转移电阻。比色法和电化学测定法分别以70 μU/mL和0.55 μU/mL的检测限测定DPP-IV。同时，所提出的方法用于测定DPP-IV抑制剂，结果令人满意。比色法和电化学方法对于DPP-IV活性测定和抑制剂筛选都简单、快速且灵敏度足够。结果还表明，基于AuNP的比色测定法可以转化为具有更高灵敏度的增强型表面 tethered 电化学测定法。简单的检测原理可能会扩展到其他操作程序简便的肽酶生物传感器的设计中。
