Gold Nanoparticle-Based Colorimetric and Electrochemical Methods for Dipeptidyl Peptidase-IV Activity Assay and Inhibitor Screening

Ning Xia,Xin Wang,Xiaojin Wang,Binbin Zhou

doi:10.3390/ma9100857

Abstract

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.

Highlights

Diabetes is a group of metabolic disorder diseases
New therapies for managing this disease are focusing on modulation of the incretins glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), two peptidic hormones with glucose-dependent insulin secretion promotion and β-cell-proliferative effect [2,3]
We presented the colorimetric and electrochemical methods for dipeptidyl peptidase-IV (DPP-IV) activity assay and inhibitor screening based on the unique size-dependent optical property and the good electrical ability of AuNPs

Summary

Introduction

Diabetes is a group of metabolic disorder diseases. Type 2 diabetes, accounting for 90%–95% of all the cases, is characterized by high blood sugar, insulin resistance, and relative lack of insulin [1].Recently, new therapies for managing this disease are focusing on modulation of the incretins glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), two peptidic hormones with glucose-dependent insulin secretion promotion and β-cell-proliferative effect [2,3].these hormones show a rather short half-life to dipeptidyl peptidase-IV (DPP-IV, EC 3.4.14.5) [4].Optimistically, DPP-IV inhibitors can be used to increase the lifetime of incretins by reducing DPP-IV activity, and DPP-IV has been regarded as the prime drug target to treat and prevent type 2 diabetes [2]. many of the inhibitors, such as sitagliptin, vildagliptin, and saxagliptin, exhibited impressive intrinsic potencies by lowering the level of serum glucose, these drugs lead to some undesired side effects, such as angioedema, pancreatitis, and infective disorders [5,6]. New therapies for managing this disease are focusing on modulation of the incretins glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), two peptidic hormones with glucose-dependent insulin secretion promotion and β-cell-proliferative effect [2,3]. These hormones show a rather short half-life to dipeptidyl peptidase-IV (DPP-IV, EC 3.4.14.5) [4]. DPP-IV inhibitors can be used to increase the lifetime of incretins by reducing DPP-IV activity, and DPP-IV has been regarded as the prime drug target to treat and prevent type 2 diabetes [2]. The currently used methods for monitoring DPP-IV activity and screening of its monitoring

Methods

Results

Conclusion