Fabrication of multi-functional CuO@PDA-MoS2 mediated dual-functional fluorescence Aptamer for the detection of Hg2+ ions and chloramphenicol through desulfurization cleavage reaction and exonuclease I activity

We progress a new sensor probe for the simultaneous detection of Hg2+ ions and chloramphenicol (CAP) by integrating FAM and TAMRA fluorophore labelled phosphorothioate RNA modified *ssDNA (*-PS probe) and CuO@PDA-MoS2 nanosphere. This work also stated a simplistic method to prepare CuO@PDA-MoS2 nanosphere via in-situ growth of MoS2 on the CuO@PDA nanosphere. The multi-functional CuO@PDA-MoS2 having rich binding sites with nanoscale architecture display great potential as an adsorbents for FAM-*ssDNA-TAMRA owing to the several interaction between them. This is lead to robustly quenching the fluorophores emission and minimizing the signal to noise ratio because of the FRET mechanism. In the developed sensor probe consisted of two interaction sections: Hg2+-induced cleavage of the PS-probe can efficiently liberates the FAM fluorophore, leads to remarkable enhancement of FAM emission. Second, the CAP can preferentially bind with remaining ssDNA-TAMRA and the formed CAP-ssDNA-TAMRA complex can be released from CuO@PDA-MoS2 surface, resulting in the regaining of TAMRA emission. Sequentially, the introduction of Exo I is to prompt and digest the CAP-ssDNA-TAMRA complex, caused in the significant regaining of TAMRA emission. Concurrently, the released CAP mediates a new digestion cycle, tends to result in ultra-trace detection of CAP. Under optimal circumstances, the suggested detecting scheme remarkably achieved for the extremely sensitive and selective detection of Hg2+ and CAP with in a wide linear range (0-10 nM Hg2+ and 0-5 nM CAP) and limit of detection 86 and 45 pM, respectively. Our current method is simpler and less expensive than existing methods of detecting Hg2+ and CAP in real water samples. More importantly, the presented approach can be detect the targets simultaneously and/or sequentially without loss of detection accuracy.

Automated summary

We have developed a new sensor probe for the simultaneous detection of Hg2+ ions and chloramphenicol (CAP) by integrating FAM and TAMRA fluorophore labelled phosphorothioate RNA modified *ssDNA and CuO@PDA-MoS2 nanosphere. The probe demonstrated high sensitivity and selectivity with a wide linear range and low limit of detection. This approach provides a simpler, more cost-effective method for the detection of Hg2+ and CAP in real water samples.