To investigate the role of source tumor cell membrane cloaking during P-TN-Dox@CMmediated tumor in vivo imaging, a comparison of fluorescent imaging between P-TN-Dox and P-TN-Dox@CM nanogels were carried out. Full spectrum in vivo fluorescence imaging system was employed to track the nanogels in 4T1 tumor-bearing Balb/c mice at different time intervals, and the corresponding fluorescence signal intensity was quantified by ImageJ software. As Figure and 5b shown, the fluorescence signal intensity of P-TN-Dox@CM nanogels in tumors was much higher than that of P-TN-Dox nanogels, demonstrating the efficient intratumoral accumulation of these cell membrane-enveloped nanogels relying on the excellent homologous active targeting effects. Besides, the intratumoral accumulation of P-TN-Dox@CM nanogels constantly elevated with the time and reached a peak level at 24 h post intravenous injection, which can be regarded as the suggested time point of the 808 nm laser irradiation for optimal therapy efficiency. Subsequently, the tumors and major organs (heart, lung, kidney, intestine, spleen and liver) of the mice were harvested and ex vivo imaged to explore the biodistribution of P-TN-Dox and P-TN-Dox@CM nanogels. As shown in Figure and, the quantitative analysis pointed out that the P-TN-Dox@CM nanogels exhibited 3.27-fold higher intratumoral accumulation than that of P-TN-Dox nanogels, further revealing the superiority of source tumor cell membrane cloaking strategy. The P-TN-Dox and P-TN-Dox@CM nanogels were both metabolized quickly in the main organs aside from the spleen and liver. Accordingly, the noninvasive fluorescence imaging offers spatiotemporal resolution information of the therapeutics accumulation in tumor, thus assisting to designate the optimal time window after intravenous injection for irradiation. The praiseworthy accumulation and prolonged retention of P-TN-Dox@CM nanogels in the tumor sites also contributed to the subsequent boosted chemotherapy effect and hyperthermia.