Multi-scale numerical simulations of photothermal therapy for tumors based on PDA-coated gold nanoparticles

This paper presents a multiscale computational model, 'micro-to-meso-to-macro', to simulate polydopamine coated gold nanoparticles (AuNP@PDA) for assisted tumor photothermal therapy (PTT). The optical properties, mainly refractive index, of the PDA unit molecules are calculated using the density functional theory (DFT) method in this multiscale model. Subsequently, the thermodynamic properties, including thermal conductivity and heat capacity, of the PDA cells and AuNP@PDA particles are calculated using molecular dynamics (MD) simulation. The absorption and scattering coefficients of the AuNP@PDA particle at the mesoscale were calculated using the finite element method (FEM) with the given input parameters. Subsequently, the photothermal conversion ratio was calculated. Finally, the photothermal conversion ratio was used in the macroscale PTT model to calculate the tumor temperature and thermal damage ratio. The calculated absorption peak of AuNP@PDA is red-shifted by 32 nm compared to that of AuNPs, while the experimental value was 38 nm. The photothermal conversion ratio of AuNP@PDA is 35.33%, which is higher than that of AuNPs (21.31%). The experimental values of AuNP@PDA and AuNPs were 33% and 23%, respectively. Moreover, the temperature change of the AuNP@PDA solution after laser irradiation closely matched the experimental findings. The results indicate the validity of the multiscale method used in this study. This multiscale computational strategy provides new insight into the study of the properties of complex systems in the absence of experimental material property data.