Fig. 2.

The interaction of AuNP-COOH with His-tagged GFP variants. Fluorescence (λ_ex=475 nm, λ_em=510 nm) titrations between nanoparticles and GFPs (100 nM) in (a) 5 mM phosphate buffer (PB), and (b) PBS buffer (150 mM NaCl in 5 mM PB) at pH 7.4. The complex association constant (K_S) and the binding stoichiometry (n) were determined using previously reported method.²¹