pH-induced highly sensitive fluorescence detection of urea and urease based on carbon dots-based nanohybrids

Carbon quantum dots (CDs) have become one of the most popular fluorescent materials due to their intriguing performance, which are favored by many fields. However, it is difficult to synthesize CDs with high quantum yield by the simple synthesis methods. In this paper, we fabricated CDs- silicon (SiO₂) spheres composites via a versatile hydrothermal route. The prepared BCD-SiO₂ composites exhibited an approximately 10-fold increase in the fluorescence intensity over that of BCDs. At the same time, the purification path was simplified by the facile separation of SiO₂ spheres. The prepared BCD-SiO₂ composites were used to fabricate a special sensing platform for the ultrasensitive detection of urea and urease, with detection limits of 1.67 μM and 0.002 mg/mL, respectively. Furthermore, this strategy was successfully applied to the detection of real samples. This result shows that as-prepared BCDs-SiO₂ composites are promising for broad application to biological analysis.