Impact of protein corona on the optical properties of gold nanoparticles in blood.

Gold nanoparticles (AuNPs) exhibit significant potential in photothermal therapy and bioimaging due to their localized surface plasmon resonance (LSPR) effect and biocompatibility. However, the formation of a protein corona on the nanoparticle surface in blood can substantially alter their optical properties, yet a systematic analysis of its influence remains limited. To address this, this study established a gold-protein corona core-shell structure model and systematically investigated the modulation mechanisms of PC parameters (thickness and complex refractive index) on the optical responses of AuNPs in blood environments using Mie scattering theory. The results demonstrate dynamic spectral responses under varying PC parameters, with maximum redshifts of 23.11 and 42.57 nm observed in absorption and scattering peaks, respectively. Compared to pure AuNP systems, the formation of a PC reduced both absorption and scattering efficiencies. Under a fixed PC refractive index, absorption and scattering efficiencies exhibited a negative correlation with increasing PC thickness. Conversely, a constant PC thickness led to reduced scattering and absorption with elevated refractive indices. At a PC refractive index of 1.30 and a thickness equivalent to 1.4 times the core diameter, the maximum attenuation amplitudes of absorption and scattering efficiencies reached 93.9% and 95.6%, respectively, compared to pure AuNPs. For a PC containing absorbing media, absorption and scattering peaks remained stable regardless of the medium's absorption capacity. The absorption efficiency increased by up to 14.6%, while the scattering efficiency decreased by 12.2%. This study establishes the first quantitative model linking PC parameters to LSPR responses in blood environments, to our knowledge, providing theoretical insights for optimizing photothermal therapy efficiency and developing PC detection technologies based on LSPR shifts.