Table 4. Typical Procedures for Site-Specific Coupling of Biomolecules to Au Surfaces.

entry	linker	coupling strategy	typical procedurea	benefits	risks
a	Pro-Linker	linker synthesized by multistep synthesis according to ref (73) and commercially available from the authors; coupling employing host–guest, bipolar, and van der Waals interactions with biomolecule functional groups	gold chip was incubated in 3 mM solution ProLinker B solution in CHCl3 for 1 h at room temperature; after rinsing and drying, the chip was incubated in 100 μg/mL PBS IgG solution for 1 h at room temperature	• site-specific coupling	• multistep procedure required
					• high cost
					• high time
b	Diels–Alder	linker and modified biomolecules synthesized by multistep synthesis according to ref (74) and not commercially available; coupling employs click chemistry between them	gold chip was immersed in the linker solution (1.0 mM) in EtOH at room temperature in a scintillation vial for 12–16 h; the surface was the treated with modified biomolecules (5 mM in water) for 4 h at room temperature	• site-specific coupling	• multistep procedure required
					• high cost
					• high time

^aInspired by refs (73 and 74).