Carbon nanoparticles with oligonucleotide probes for a label-free sensitive antibiotic residues detection based on competitive analysis.

Carbon nanoparticles (CNPs) have been combined with aptamer, providing a broad application in small molecule. CNPs can be quenched by small molecules and are usually applied as luminescent probes because of their photophysical characteristics. In this work, we developed a competitive analysis for antibiotic residues detection based on carbon nanoparticles (CNPs) and oligonucleotide probes. Oligonucleotide probes including oxytetracycline (OTC) aptamer was exploited for recognition OTC and was used to restore the luminescence. Tetracycline (TC), as a competitor of OTC, was utilized to quench the luminescence of CNPs and reduce the sample matrix effect. Under optimal conditions, the linear rang of OTC was 0.010~1.0 ng/mL with the relative standard deviations (RSDs) from 2.91% to 11.3%, and the limit of detection (LOD) was low to 0.002 ng/mL. Moreover, the proposal was successfully applied to analyze OTC from drink water, indicating that this approach has great potential for other small molecule analysis.