Microstructure evolution of sandwich graphite oxide/interlayer-embedded Au nanoparticles induced from γ-rays for carcinoembryonic antigen biosensor

Abstract

With the capability of inducing small particle sizes of supported metal in graphite oxide (GO), the γ-ray irradiation method applied for preparing graphite oxide-gold (GO-Au) nanocomposites as electrochemical immunosensors has attracted specific attention recently. To study the accurate factors influencing the precise morphology and final performance of the prepared composites in the γ-irradiation system, we proposed a facile method to investigate the evolution of the GO structure, size and dispersion of Au nanoparticles (AuNPs) produced with the addition of isopropyl alcohol to the system. The GO-Au nanocomposites were characterized by Fourier transform infrared spectroscopy, x-ray diffraction spectra, Raman spectra, x-ray photoelectron spectroscopy and high resolution transmission electron microscopy. These nanocomposites with sandwich morphology exhibited an excellent immunosensor performance with a low detection limit of 15.8 pg ml −1 (S/N=3) and a wide linear range from 1 to 40 ng ml −1 for detecting carcinoembryonic antigens. The enhanced biosensing performance is attributed to the synergistic effect of γ-irradiation and the precise structure of GO, which endows the smaller size and more uniform distribution of AuNPs on the GO as well as the good signal amplification capability. Furthermore, adopting the γ-irradiation method and use of GO as a precursor is propitious for application in large-scale production because of its high-efficiency and high-yielding characteristics.

Mechanistic Insight into the Limiting Factors of Graphene-Based Environmental Sensors

“…Here, we address the need for in-depth inquiry into the sensing mechanisms by studying for the first time devices based on chemical vapor deposition (CVD)-grown graphene as they are exposed to one of the most common volatile organic compounds (VOC), ethanol. Currently, sensors based on large-scale high-quality graphene growth methods such as CVD are less explored than chemical derivatives of graphene. − We find that, contrary to previous reports, small residues at the surface of graphene dramatically affect its electrical properties in gas sensing applications. We explore the consequences of distinct surface treatment procedures and interpret them by corroborating microscopic surface studies obtained by scanning probe microscopy and theoretical calculations of molecule/surface interactions.…”

“…47 The force field parameters for PMMA were taken from literature 48 with a modified ester-methyl group torsion. 49 Three different amounts of ethanol (23,115, and 230 molecules in simulation box) and two lengths of PMMA polymer (3mer and two 8-mers of MMA fragments) were considered. Initially, ethanol molecules were placed randomly on one side of the graphene/ graphene polymer system within a distance of 5 nm from the surface.…”

Constructing Conductive Channels between Platinum Nanoparticles and Graphitic Carbon Nitride by Gamma Irradiation for an Enhanced Oxygen Reduction Reaction

“…), where e − aq is the active and powerful reducing free radical, while •OH is the dominant oxidizing free radical. 24 The adsorption of [PtCl 6 ] 2− ions on g-C 3 N 4 reduced them to metal Pt species by reducing the free radicals generated from gamma irradiation. Meanwhile, isopropanol (IPA) as a solvent in the solution could effectively exfoliate g-C 3 N 4 .…”

“…When gamma rays irradiated the aqueous solutions, water molecules were decomposed into reducing groups (e – aq ,·H) and oxidizing groups (·OH, H 2 O 2, etc. ), where e – aq is the active and powerful reducing free radical, while ·OH is the dominant oxidizing free radical . The adsorption of [PtCl 6 ] 2– ions on g-C 3 N 4 reduced them to metal Pt species by reducing the free radicals generated from gamma irradiation.…”

Detection of Six β-Agonists by Three Multiresidue Immunosensors Based on an Anti-bovine Serum Albumin-Ractopamine-Clenbuterol-Salbutamol Antibody

“…Electrochemical immunosensors are a new class of sensors that combine highly sensitive electrochemical sensing technology with highly specific immunological techniques. − Based on the specific binding of the antigen and antibody, the electrochemical immunosensor analysis can detect the change of the antigen–antibody conjugate and convert the nonelectric signal into an electrical signal , so as to realize the correlation between the electric signal and the concentration of the substance to be tested, which is a relatively advanced detection method and has broad application prospects in food, environment, and other fields. − Poo-arporn et al prepared a disposable electrochemical sensor for determination of RAC with a detection limit of 13 nM (S/N = 3) . A disposable electroanalytical device for the competitive enzyme-linked immunosorbent assay of phenylethanolamine A (PA) was reported by Deng et al with a detection range of 0.005–60 ng·mL –1 and a detection limit of 2.6 pg·mL –1 .…”