Banerjee, Indranil

In this study, we have investigated the effect of variants of BSA on the NIR-induced phototherapeutic performance of the BSA-ICG complex to identify the best BSA variant for complexing with ICG. Three variants of BSA, namely BSA-A7030 (protease, fatty acid, and globulin free), BSA-A3059 (protease & globulin free), and BSA-A3294 (only protease free), were chosen. UV-vis-NIR absorption, fluorescence, and CD spectroscopy studies showed no significant difference in the spectra of all the BSAs, but in the presence of Cu2+, a differential reactivity of the three BSA variants was noticed. The biophysical study of the BSA-ICG complexes (1 : 1 molar ratio) showed that post-binding, there was a significant red shift of the ICG peak (both absorption and fluorescence) for BSA-A7030 with a widening of the excitation-emission hotspot. The photothermal properties of the BSA-ICG complexes under NIR (808 nm) exposure were similar to those of free ICG, whereas the photodynamic property increases for BSA-A3059. All the BSA-ICG complexes were found to be cytocompatible when tested with the NIH 3T3 cell line in vitro. The effect of the BSA type on the 808 nm NIR-mediated phototherapeutic properties of the BSA-ICG complex was tested in vitro on lung cancer cell line A549 (2D model) and a 3D osteosarcoma spheroid model. The study showed a NIR-induced cytoskeletal disruption of A549 cells with maximum damage caused by the BSA-A7030-ICG complex. The same complex was found to show the highest phototherapeutic effect on the 3D spheroid model. This study implied that an appropriate BSA variant is crucial for BSA-ICG complex-mediated NIR phototherapy. © 2025 RSC.