Abstract
In this report, a novel fluorescent sensing platform using nitrogen-doped carbon dots (N-CDs) as probes for fluorescence signal transmission has been designed for the detection of significant biomolecules pyrophosphate (PPi) and alkaline phosphatase (ALP). The high fluorescent N-CDs could be selectively quenched by Cu2+, and recovered by the addition of PPi because PPi preferentially binds to Cu2+. Once ALP was introduced into the system, ALP can specifically hydrolyze PPi into Pi, the intense fluorescence of N-CDs could be quenched again due to the recombination of the as-released Cu2+ with N-CDs. So, fluorescence of N-CDs is regulated by an ALP-triggered reaction. Based on this strategy, we demonstrated that N-CDs could serve as a very effective fluorescent sensing platform for label-free, sensitive and selective detection of PPi and ALP with low detection limit of 0.16 μM and 0.4 U/L for PPi and ALP, respectively. Moreover, the assay time is just around 0.5 min for PPi and 30 min for ALP. This developed strategy shows remarkable advantages including sensitive, rapid, simple, convenient, and low-cost and so forth. Furthermore, this method was also successfully applied to monitor ALP in human serum, which indicates its great potential for practical applications in biological and clinical diagnosis.
Highlights
Up to date, many techniques have been developed for the detection of PPi and alkaline phosphatase (ALP) including colorimetric[10, 11], fluorometric[12, 13], surface-enhanced Raman scattering[14] and electrochemical methods[15, 16]
Experimental results demonstrate that this proposed assay has robust ability for quantitative analysis of both PPi and ALP activity with high sensitivity, low cost, good selectivity and rapidity as well as simplicity, which are highly desired for the screening of PPi and ALP in clinical diagnostics and other biomedical applications
In the Fourier transform infrared (FT-IR) analysis of nitrogen-doped carbon dots (N-carbon dots (CDs)), the following were observed: stretching vibration of O–H at 3408 cm−1 and C–H at 2930 cm−1, stretching vibration and bending vibration of N–H at 3256 cm−1 and 1586 cm−1, bending vibration of the C–O at 1401 cm−1 and the stretching peak of C–O–C at 1111 cm−1, C–N stretching vibration at 1246 cm−1 (Fig. 1d)[43,44,45]. These results indicate that there are abundant of hydroxyl, amino and carboxyl group on the surface of the N-CDs
Summary
A novel fluorescent sensing platform using nitrogen-doped carbon dots (N-CDs) as probes for fluorescence signal transmission has been designed for the detection of significant biomolecules pyrophosphate (PPi) and alkaline phosphatase (ALP). This developed strategy shows remarkable advantages including sensitive, rapid, simple, convenient, and low-cost and so forth This method was successfully applied to monitor ALP in human serum, which indicates its great potential for practical applications in biological and clinical diagnosis. The fluorescence of N-CDs could be quenched by Cu2+, and recovered by the addition of PPi. ALP could hydrolyze PPi into Pi, the intense fluorescence of N-CDs could be quenched again due to the recombination of the as-released Cu2+ and N-CDs. Experimental results demonstrate that this proposed assay has robust ability for quantitative analysis of both PPi and ALP activity with high sensitivity, low cost, good selectivity and rapidity as well as simplicity, which are highly desired for the screening of PPi and ALP in clinical diagnostics and other biomedical applications
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