In order for a compound to attach to a gold nanoparticle, it must have the following properties:
1. Antioxidant/reducing property. It must be able to donate electrons to Au3+ ions in order to "stick"
2. Capping/stabilization property. the antioxidant must prevent "clumping" of nanoparticles into macroparticles by coating the gold ion.
3. Specific chemical features required. Phenolic hydroxyl groups and aromatic rings are highlighted for suitable candidates.

Polyphenols (such as molecules found in green tea), other molecular compounds may suit this purpose:
A. Flavonids: Many flavonids, such as quercetin, rutin, luteolin and genistein are less complex molecularly, but still contain reduction and capping capacity, some with known theraputic applications.
B. Anthocyanins: Natural pigments found in fruits and vegetables with multiple hydroxyl groups and aromatic systems.
C. Tannins: Highly branched polyphenol subgroup with many phenolic hydroxyl groups, such as tannic and gallic acid.
D. Lignins and Lignans: Complex polymers and dimers derived from plant cell walls
E. Thiol (-SH) groups: Compounds such mercaptobenzoic acid, Cysteine and Glutathione, are not phenolic, they are strong reducing agents and are well-known for stabilizing nanoparticles with Au-S bonds, potentially delivering other compounds.
F. Amino Acids: Tyrosine, Tryptophan, Cysteine and Methionine, respectively, contain a spread of aromatic rings, sulfur atoms required for Au-S bonds, and phenolic hydroxyl groups. This could be used for sequence delivery methods displaying reducing and capping abilities.
G. Carboxylic and Hydroxy Acids: Citric Acid, Tartaric Acid and Ascorbic acid are commonly used in green synthesis that contain enediol groups rather than being phenolic, still presenting reducing ability to gold nano-particles for enhance delivery.
H. Synthetic Antioxidants: Candidates such as Propyl gallate, hydroquinones and catechols are strong electron donors that can act as capping agents.