Recent developments in the colorimetric sensing of biological molecules using gold nanoparticles-based probes

•Colorimetric sensing of various classes of biological molecules has been discussed.•Recognition of chiral forms of amino acids has been presented.•Colorimetric discrimination of proteins has been discussed.•Mechanisms of colorimetric sensing of biological molecules has been provided. The localized surface plasmon resonance (LSPR) phenomenon of the noble metal nanoparticles is responsible for their strongly coloured colloidal solutions. The colorimetric or colour-based detection generally relies on the aggregation of the metal nanoparticles in the presence of the analyte. In this review, the sensing of numerous classes of biological molecules such as amino acids, proteins, DNA bases, neurotransmitters and vitamins have been discussed using gold nanoparticles (GNPs) - based probes. The performance characteristics of the probes such as linearity range and limit of detection (LOD) have been presented in a tabular form. The colorimetric recognition of the chiral enantiomers of amino acids has been discussed with the help of pertinent examples. The GNPs-based colorimetric quantification and differentiation of several proteins has also been presented in the review. The mechanisms of the sensing of biological molecules in the presence of the GNPs have been discussed in detail. Hydrogen-bonding interaction and coulombic-bridging between the analyte and the GNPs were found to induce the agglomeration of the particles in most of the systems. [Display omitted]