Bio-initiated light addressable potentiometric sensor for unlabeled biodetection and its MEDICI simulation

Abstract

A bio-mimetic anchoring strategy based on L-3,4-dihydroxyphenylalanine (L-DOPA) was exploited to activate the surface of light addressable potentiometric sensor (LAPS), with the structure of Si₃N₄/SiO₂/Si. X-Ray photoelectron spectroscopy (XPS) measurements were carried out to ascertain its existence. The protein's immobilization on L-DOPA-initiated LAPS were also tested by our LAPS system. Then L-DOPA-activated LAPS were applied in the unlabeled rabbit anti-mouse immunoglobulin (IgG) detection. The maximum sensitivity of L-DOPA-activated LAPS to antigen (Ag) is about 5.68 nA/p[Ag]. LAPS responses in IgG measurements were from 95 to 180 nA, when the concentration was varied from 0–4 μg mL⁻¹. These experiments show that L-DOPA is an available material for LAPS surface modifications. At the same time, simulations based on MEDICI (Synopsys™) were performed. The simulated curves are in accordance with experimental data which demonstrate our theoretical analysis for the experimental phenomenon, and indicate the feasibility of simulating biological electronic devices with MEDICI.