Synthesis of PtPb hollow nanoparticles and their application in an electrochemical immunosensor as signal tags for detection of dimethyl phthalate

Abstract

Platinum–lead (PtPb) hollow nanoparticles were used as signal tags for the first time to fabricate an electrochemical immunosensor, which was then used as the first electrochemical immunosensor to detect dimethyl phthalate (DMP). Pt nanoparticles possess good biocompatibility, highly efficient catalytic properties and good electrical conductivity. Pb was introduced to produce electrochemical signals, reduce the dosage of the noble metal and save costs. An AuPt–graphene sheet (AuPt–GS) was used to immobilize the DMP antibodies (Anti-DMP) due to its excellent conductivity and large surface area. A novel competitive immunoassay was proposed, using PtPb nanoparticles covalently conjugated with bovine serum albumin (BSA)–DMP for the sensitive detection of DMP concentrations. The quantitative detection was based on the competitive binding of DMP antibodies with PtPb-tagged DMP or free DMP. The electrochemical signal decreased with increasing concentration of the free DMP as the amount of PtPb–BSA–DMP tags decreased at the immunosensor. Electron microscopy, energy dispersive spectrometry, X-ray powder diffraction and a series of electrochemical techniques were used to characterize the nanoparticles. Differential pulse voltammetry was used to monitor the electrochemical response. The immunosensor exhibited a linear response from 1 to 1000 ng mL⁻¹ DMP with a detection limit of 0.33 ng mL⁻¹. The excellent performance of the PtPb nanoparticles showed promising applications as a sensor platform.