Fig. 4.

Tumor targeting (passive) and renal clearance of renal clearable NPs with different sizes. The NP size, renal clearance and targeting efficiency, were plotted from the data sets in Table S1 in supplementary information. As a result, the NPs with more efficient renal clearance (> 80%ID) would generally have lower targeting efficiency (< 3%ID/g). Meanwhile, the renal clearable PEG-AuNPs (asterisk (*) in the figure) were found to have higher tumor targeting efficiency compared to other NPs of similar sizes, which might be due to the density-dependent margination effect in tumor blood flow and resulting enhanced NP extravasation, ref. [156]. To be noted, the renal clearance efficiencies were mainly quantified based on the recovery percentages (ranging from 24 to 168 h post-injection) of the administrated NPs in urine from the reports; the targeting efficiencies were analyzed as the NP accumulation in tumor at selected time points (at least 6 h post-injection) from the reports.