Furthermore, the Dox release kinetic mechanism from P-TN-Dox@CM nanogels was explored by different fitting models. The linear correlation coefficients (R 2 ) denoted the fitting precision of various models. As presented in Figure and Table , the Dox release curves were not well fitted with zero-order model. When the Dox release profiles were fitted with Higuchi model, which was widely used in swellable polymer systems due to its simplicity, all the diffusion constants (k2) were higher than 1, suggesting the domination of Fickian diffusion in the drug release behaviors. Peppas-Sahlin model was the optimal fitting kinetic model with the highest linear correlation coefficients (R 2 ＞0.95) to describe the Dox release behaviors from P-TN-Dox@CM nanogels. In this model, the effects of Fickian diffusion (item 1) and case II transport (item 2) were considered. The results showed that k3 was significantly higher than k4, further indicating that Fickian diffusion dominated in the Dox release mechanism. (25, 37, and 42 °C).