One-Step Synthesis of Water-Dispersible and Biocompatible Silicon Nanoparticles for Selective Heparin Sensing and Cell Imaging.

A sensitive and selective fluorescence "turn-off" sensor to detect heparin using water-soluble silicon nanoparticles (Si NPs) was developed for the first time. The Si NPs were synthesized by a simple one-step procedure, which did not need high-temperature and complex modification. The as-prepared Si NPs featured strong fluorescence, favorable biocompatibility, and robust photo- and pH stability. Significantly, the Si NPs were induced to assemble or aggregate via hydrogen bonding, which resulted in the fluorescence of Si NPs quenched. Under the optimized conditions, the linear range was obtained from 0.02 to 2.0 μg/mL, with a limit of detection of 18 ng/mL (equal to 0.004 U/mL). It was lower than the proper therapeutic level of heparin during cardiovascular surgery and long-term therapy. This proposed method was relatively free of interference from heparin analogues, which commonly existed in heparin samples and could possibly affect heparin detection. Moreover, it did not need to introduce any control medium. As expected, the method was successfully applied to detect heparin in human serum samples with satisfactory recovery ranging from 98.8 to 102.5%. The Si NPs were superbly suitable for cell imaging owing to the negligible cytotoxicity and excellent biocompatibility.