Immunoglobulin G-Encapsulated Gold Nanoclusters as Fluorescent Tags for Dot-Blot Immunoassays

Abstract

Few-atom gold nanoclusters (AuNCs) have been fabricated and used for various fields owing to their remarkable optical and photophysical features. However, the rational design for the antibody-mediated synthesis of fluorescent AuNCs for direct antigen–antibody reactions remains unexplored. In this work, immunoglobulin G (IgG)-functionalized AuNCs (IgG-AuNCs) were successfully prepared via a facile and fast biomineralization process. The generated IgG-AuNCs can emit intense red fluorescence with a high photoluminescence quantum yield. Besides strong emission, the bioactivity of IgG on the IgG-AuNCs can be retained. Surface plasmon resonance measurements suggested that IgG-AuNCs can bind to goat anti-human IgG with an affinity constant of 6.21 × 10–8 M. A simple detection method was then developed using a dot-blot immunoassay with IgG-AuNCs as fluorescent tags. Experimental results confirmed that the IgG-AuNC-based fluorescent reporters had many advantages such as low nonspecific adsorption and good photostability, offering immense potential for the development of efficient biosensors. This work can be extended to other specific antibodies to produce multifunctional AuNCs and utilized to detect and monitor targeted analytes and biological events of interest.

Fabrication of avidin-stabilized gold nanoclusters with dual emissions and their application in biosensing

“…1 B). The photoluminescence quantum yield (PLQY) of Av–Au NCs in aqueous solution was ~ 19.4%, which was obviously higher than that of previously reported Prot-Au NCs [ 38 ]. Chevrier’s group [ 39 ] used proteases to degrade the outer shell of BSA-stabilized Au NCs, causing a decrease in fluorescence intensity and quantum yield.…”

“…X-ray photoelectron spectroscopy (XPS) was performed to detect the chemical state of gold in Av–Au NCs that emit pink fluorescence. According to the literature, the gold core of Au 8 NCs is completely composed of Au (0) [ 20 ], whereas that of Au 25 NCs is composed of Au (0) and Au (I) [ 38 ]. Thus, the Av–Au NCs that emit pink fluorescence should contain both Au (0) and Au (I).…”

Direct imaging of antigen–antibody binding by atomic force microscopy

“…Antigen–antibody binding research has particular significance in medical diagnosis, vaccine exploration, immunological study and disease mechanism analysis (Nergiz et al 2019 ; Bruno et al 2019 ). In recent years, many immunoassay methods have been used to detect antigen–antibody binding, which include many additional biochemical reagents (Meyer et al 2020 ; Stentzel et al 2015 ; Zhuang et al 2019 ). The extensive use of biochemical agents not only requires tedious process, but also causes serious environmental pollution.…”

Fabrication of a paper strip for facile and rapid detection of bovine viral diarrhea virus via signal enhancement by copper polyhedral nanoshells

“…[15][16][17][18] The advantages of dot-blot assays are simplicity, rapidity, and not requiring skilled labor, which could make it possible to simply screen BVDV in the eld. [19][20][21] In other words, by combining this nanomaterial with the dot-blot immunoassay method, the detection performance could be highly improved. 22 To enhance the optical signal reecting the amount of BVDV in the sample, the copper polyhedral nanoshell (CuP) growth on the surface of AuNPs was introduced (Scheme 1).…”