Phenolic compounds mediated biosynthesis of gold nanoparticles and evaluation of their bioactivities: A review

Gold nanoparticles (AuNPs) have been applied in a variety of fields based on their unique physical and chemical properties. Phenolic compounds (PCs) are the largest variety of phytochemicals in foods and have received substantial attention owing to their extraordinary health benefits. Recently, extensive studies have been conducted on the synthesis and conjugation of PCs onto AuNPs (AuNP/PC) characterisation, their bioactivities such as antimicrobial, anticancerous, anti-inflammatory. PCs served the dual roles, i.e., as reductant and stabiliser during the synthesis of AuNPs/PC in a one-pot process. The synthesis parameters for AuNP/PCs and the characteristic properties of as-synthesised AuNP/PCs should be evaluated to achieve the highly efficient bioactivities. Therefore, the critical criteria for the synthesis of AuNP/PC such as the temperature, pH, and molar ratio of the precursors are reviewed. It is found that the PCs mediated reduction of gold salt can provide the well dispersed and stable AuNPs with a high negative surface charge (-15 to -54 mV) and an average SPR band ranging from 520 to 600 nm. The presence of surface hydroxyl groups in AuNP/PCs was the indication of successful conjugation of PCs with AuNPs. It can be concluded that the synergistic effect of the PCs-conjugated AuNPs greatly enhanced their bioactivities.