Fig. 2

Calcium salt binding assay of the designed bone-targeted agents under NIR-I and NIR-II filters. 760 nm excitation and 785 nm LP filters were used for NIR-I imaging, and 808 nm excitation and 1,070 nm LP filters for NIR-II imaging. a 5 µM of each fluorophore in 10% FBS was imaged. b Calcium-salt binding assay of the bone-targeted agents. SBRs were calculated by dividing the fluorescence intensity of each fluorophore by the signal intensity of each blank (which include only calcium salt and PBS). Data is expressed as mean ± S.D. (n = 3): *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. HA, hydroxyapatite; CC, calcium carbonate; CP, calcium phosphate; CO, calcium oxalate; CPP, calcium pyrophosphate