Fig. 1. (a) The mode of pH controlled covalent and noncovalent interaction of SqNPs with BSA protein. (b) Time dependent fluorescence response of 16 : 1 BSA–SqNPs at 700 nm (λ _ex@640 nm). (c) Fluorescence response of SqNPs towards BSA protein (0–96 μM) followed by the addition of DNSA (0–120 μM). Experiments were performed using a 6 μM SqNP solution in a 25 mM phosphate buffer at pH 4.0.