Using Monoclonal Antibody to Determine Lead Ions with a Localized Surface Plasmon Resonance Fiber-optic Biosensor

Abstract

A novel reflection-based localized surface plasmon resonance (LSPR) fiber-optic probe has been developed to determine the heavy metal lead ion concentration. Monoclonal antibody as the detecting probe containing massive amino groups to capture Pb(II)-chelate complexes was immobilized onto gold nanoparticle-modified optical fiber (NMAuOF). The optimal immobilizing conditions of monoclonal antibody on to the NMAuOF are 189 μg/mL in pH7.4 PBS for 2 h at 25°C. The absorbability of the functionalized NMAuOF sensor increases to 12.2 % upon changing the Pb(II)-EDTA level from 10 to 100 ppb with a detection limit of 0.27 ppb. The sensor retains 92.7 % of its original activity and gives reproducible results after storage in 5% D-( )-Trehalose dehydrate solution at 4°C for 35 days. In conclusion, the monoclonal antibody-functionalized NMAuOF sensor shows a promising result for determining the concentration of Pb(II) with high sensitivity.

Keywords: biosensor; gold nanoparticle; lead-chelate complex; lead-chelate complex. antibody; localized surface plasmon resonance; monoclonal antibody.

Figure 1.

(a) Images of 2-D and 3-D AFM surfaces on the prepared MPTMS; (b) Electron micrograph and particle size distribution of pure Au nanoparticles.

Figure 2.

The chemical reactions scheme carried out for covalent binding of monoclonal antibody to the fiber-based LSPR sensor.

Figure 3.

The schematic representation of the LSPR biosensor system.

Figure 4.

An example of serial Pb(II)-EDTA complex response signal in the range of 10∼100 ppb by two sensors with/without monoclonal antibody coating.

Figure 5.

Effects of (a) the incubating monoclonal antibody concentration, (b) incubating time, and (c) pH on the response for detecting 10∼100 ppb Pb(II)-EDTA complex in pH 7.4 PBS buffer solution at 25°C.

Figure 6.

Effect of the detection temperature on the response for detecting 10∼100 ppb Pb(II)-EDTA complex in pH 7.4 PBS buffer solution at 25°C.

Figure 7.

Comparison of the responses between different metal-chelate complexes (i.e., Mg(II)-, Cu(II)-, and Ni(II)-EDTA) through the monoclonal antibody-functionalized LSPR biosensor.