A colorimetric biosensor based on guanidinium recognition for the assay of protein tyrosine phosphatase 1B and its inhibitors

Abstract

In this study, a colorimetric biosensor was established for the detection of protein tyrosine phosphatase 1B (PTP1B) and its inhibitor based on the guanidinium recognition assisted coordination of arginine-glycine-cysteine (RGC) modified gold nanoparticles (RGC/AuNPs) with 4-aminophenyl phosphate-functionalized Fe₃O₄ magnetic nanoparticles (MNPs/APP). PTP1B can catalyze the cleavage of the phosphate ester bond and the departure of the phosphate acid group from the surface of MNPs/APP, resulting in the loss of the corresponding coordination reactivity. Upon the addition of a solution of RGC/AuNPs, RGC/AuNPs remained in the supernatant solution after magnetic separation and a high absorbance value was observed. Thus, a simple colorimetric biosensor for PTP1B assay was developed. Under the optimized experimental conditions, PTP1B was detected within a linear range of 0.002 U mL⁻¹ to 0.08 U mL⁻¹ with the lowest detection limit of 0.0013 U mL⁻¹. Moreover, using this proposed biosensor, the inhibition effect of betulinic acid and 6-chloro-3-formyl-7-methylchromone on PTP1B is determined with IC₅₀ values of 9 μM and 15 μM, respectively. Therefore, this new biosensor not only has great potential for PTP1B analysis but also for the detection of its inhibitors.