Investigations on the Interaction between Cuprous Oxide Nanocubes and Bovine Serum Albumin with Comprehensive Spectroscopic Methods

The interaction between cuprous oxide (Cu(2)O) nanocubes and bovine serum albumin (BSA) was investigated from a spectroscopic angle under simulative physiological conditions. Under pH 7.4, Cu(2)O could effectively quench the intrinsic fluorescence of BSA via static quenching. The apparent binding constant (K(A)) was 3.23, 1.91, and 1.20?×?10(4) M(-1) at 298, 304, and 310 K, respectively, and the number of binding sites was 1.05. According to the Van't Hoff equation, the thermodynamic parameters (ΔH° = -63.39 kJ mol(-1), ΔS° = -126.45 J?mol(-1) K(-1)) indicated that hydrogen bonds and van der Waals forces played a major role in stabilizing the BSA-Cu(2)O complex. Besides, the average binding distance (r(0)?= 2.76 nm) and the critical energy transfer distance (R(0) = 2.35 nm) between Cu(2)O and BSA were also evaluated according to F?rster's non-radioactive energy transfer theory. Furthermore, UV-visible and circular dichroism results showed that the addition of Cu(2)O changed the secondary structure of BSA and led to a decrease in α-helix. All results showed that BSA underwent substantial conformational changes induced by Cu(2)O, which can be very helpful in the study of nanomaterials in the application of biomaterials.