Before performing
in vivo imaging, we designed a dose escalation experiment using three dose schemes (1, 5, and 10 mg kg
-1) over 35 days to further evaluate
in vivo biocompatibility in three healthy adult cynomolgus monkeys (Figure
2(a)). No IV injection of AIE probes in cynomolgus monkeys has been reported to our knowledge. Therefore, the escalating of IV injection dose of AIE probes could effectively investigate the safety of the monkeys and detect the tolerated ability of AIE probes. The cumulative IV dose reaches 16 mg kg
-1 (equivalent IV dose of an adult human ~5.3 mg kg
-1,
), which was more than tenfold of the IV dose of ICG (0.5 mg kg
-1) for NIR-II fluorescence imaging in clinical trials [
25,
26]. Therefore, the designed dose-escalating experiment could be used to evaluate the tolerance of as-prepared AIE probes in cynomolgus monkeys. Before IV injection of AIE probes, physiological parameters and blood chemistry of three cynomolgus monkeys were measured as the control group. This experiment design can not only greatly minimize the error caused by individual differences but also potentially reduce the sample size of experimental monkeys. After IV injection of AIE probes with the dosage escalation of 1, 5 mg kg
-1, and 10 mg kg
-1, the body weight of the monkeys showed no fluctuation, indicating minimal systemic effects (Fig. S11). Similarly, there was no change in body temperatures during the test (Fig. S12). No statistically significant differences in daily behavioral patterns (eating, drinking, sleeping, and activity), neurological status, and physical features were observed (data not shown). Next, a complete blood count was conducted at regular intervals to investigate the immune response to AIE probes (Figures
2(d)–
2(q)). Results showed no sharp fluctuation in the 14 hematological indicators compared with the control and reference values, indicating no acute toxicity. Similarly, serum biochemistry assays revealed that 10 indicators of liver function (TP, A/G, ALB, ALP, ALT, AST, DBIL, GGT, GLOB, and TBIL) and 2 indicators of kidney function (CREA and UREA) were normal throughout the examination period (Figures
2(p)–
2(z-1)), suggesting no sign of liver and kidney injuries. At the end of the 36-day postinjection period, one cynomolgus monkey was randomly selected and euthanized, and its heart, liver, spleen, lung, kidney, brain, muscle, and lymph nodes were removed for histological analysis (Figure
3). Two clinical pathologists, both unaware of the AIE probe treatment, analyzed the tissue sections and found no abnormality in the myocardial fibers, no signs of inflammatory response in the liver, no pulmonary fibrosis in the lung, nor necrosis in all histological samples, and clear structure of the glomerular. These results provided preliminary evidence that AIE probes, with a cumulative IV dose of 16 mg kg
-1, did not induce acute toxicity in cynomolgus monkeys during the experimental period. Moreover, two other AIE probe-treated cynomolgus monkeys have been raised for more than ten months without any adverse response.