Colorimetric biosensing assays based on gold nanoparticles functionalized/combined with non-antibody recognition elements

Biosensing assays involving antibody-antigen interactions have been widely applied in diagnostics and healthcare in virtue of their superior selectivity and sensitivity. However, antibodies typically suffer from complex and fragile functional structures, tedious preparation (resource-intensive and time-consuming), and large molecular size. As a result, the application of antibody-based biosensors tends to be constrained by short shelf-life and limited on-site/remote applicability. To date, AuNP-based colorimetric assays have been widely employed for point-of-care diagnostics in virtue of their user-friendly nature, low cost, chemical versability, and great potential in naked-eye detection. In this review, recent advances in the development of colorimetric assays based on gold nanoparticles (AuNPs) functionalized/combined with non-antibody recognition elements (e.g., liposomes, peptides, aptamers, other chemical molecules) for naked-eye detection of various analytes (e.g., enzymes, viruses, DNAs and bacteria) are discussed in terms of performances and characteristics. Additionally, challenges and future opportunities of these assays are explored.