Nanoporous Gold Films Prepared by a Combination of Sputtering and Dealloying for Trace Detection of Benzo[a]pyrene Based on Surface Plasmon Resonance Spectroscopy

Abstract

A wavelength-interrogated surface plasmon resonance (SPR) sensor based on a nanoporous gold (NPG) film has been fabricated for the sensitive detection of trace quantities of benzo[a]pyrene (BaP) in water. The large-area uniform NPG film was prepared by a two-step process that includes sputtering deposition of a 60-nm-thick AuAg alloy film on a glass substrate and chemical dealloying of the alloy film in nitric acid. For SPR sensor applications, the NPG film plays the dual roles of analyte enrichment and supporting surface plasmon waves, which leads to sensitivity enhancement. In this work, the as-prepared NPG film was first modified with 1-dodecanethiol molecules to make the film hydrophobic so as to improve BaP enrichment from water via hydrophobic interactions. The SPR sensor with the hydrophobic NPG film enables one to detect BaP at concentrations as low as 1 nmol·L−1. In response to this concentration of BaP the sensor produced a resonance-wavelength shift of ΔλR = 2.22 nm. After the NPG film was functionalized with mouse monoclonal IgG1 that is the antibody against BaP, the sensor’s sensitivity was further improved and the BaP detection limit decreased further down to 5 pmol·L−1 (the corresponding ΔλR = 1.77 nm). In contrast, the conventional SPR sensor with an antibody-functionalized dense gold film can give a response of merely ΔλR = 0.9 nm for 100 pmol·L−1 BaP.

Enhanced Sensitivity of Surface Plasmon Resonance Biosensor Functionalized with Doped Polyaniline Composites for the Detection of Low-Concentration Acetone Vapour

“…SPR-based sensors have been successfully applied in the detection of some volatile compounds and gases like benzene, ammonia, chloroform, ethanol, methanol, ethyl benzene, 2-propanol, toluene, and acetone vapours [8,[26][27][28][29][30][31][32]. The performance of the sensors has been improved through various design modifications which include the incorporation of nanoparticles of different morphologies [33][34][35], bimetallic layers [2,[36][37][38][39], porous gold [40][41][42][43], graphene layer on gold [5,44], conducting and insulating polymer coatings [26,45,46], and metal oxide coatings [47,48]. However, SPR detection of acetone vapour has not been optimized for suitable applicability in diabetes monitoring and screening [32].…”

Recent Advances in Spectroscopy Technology for Trace Analysis of Persistent Organic Pollutants

“…However, this makes the fabrication process of the SPR sensors complicated and exhaustive. To overcome this problem, Wang et al adopted nanoporous gold (NPG) film as an effective and alternative approach for the SPR sensor in the trace detection of BaP [35]. The NPG film could not only dramatically enhance the sensitivity for the great enrichment of BaP throughout the entire thickness but also support the surface plasmon wave with a simple structure of the SPR sensor (Figure 4b).…”

“…The detection limit for BaP was 5 pmol•L −1 , which was increased by 20 times compared to that of conventional SPR sensors ( Figure 5). Therefore, this suggested that the technique in SPR sensors shows enormous potential for trace detection and monitoring of small-molecular environmental pollutants [35].…”

“…Sci. 2019, 9, x FOR PEER REVIEW 10 of 16 this suggested that the technique in SPR sensors shows enormous potential for trace detection and monitoring of small-molecular environmental pollutants [35].…”

“…(a) Schematic of polychlorinated biphenyl (PCB)-sensitive optical detection system using surface plasmon resonance, (b) Illustration of surface plasmon resonance (SPR) sensors based on the nanoporous gold (NPG) film. Republished with permission from[35,38] (Copyright © 2008, Elsevier).…”