Moreover, the bright fluorescence signal around recipient's bladder indicates that the leakage of urine from the ureterovesical suturing site (Fig. ). Quantitative analysis showed that the mean fluorescence intensity of the recipient's bladder in either the urinary leak or ureteral stenosis model was significantly reduced in contrast to the successful urinary tract reconstruction model, suggesting that the urine excreted by the donor kidney could not flow unimpeded into the bladder (Fig. ). Collectively, these results demonstrate the capability of DIPT-ICF NPs as an excellent contrast agent for fluorescent ureterography in the NIR-IIa window.