Platinum ions mediate the interactions between DNA and carbon quantum dots: diagnosis of MRSA infections

In this study, we have developed a rapid and cost-effective method employing platinum ion (Pt⁴⁺)-capped fluorescent carbon quantum dots (CQDs) coupled with loop-mediated isothermal amplification (LAMP) to detect dual MRSA genes. We synthesized nitrogen- and chlorine-co-doped fluorescent CQDs (CQD_SPDs) from spermidine trihydrochloride via a simple one-step pyrolysis. The CQD_SPDs capped with Pt⁴⁺ ions through the cooperative coordination of the amine and chlorine groups on the surface of CQDs facilitated the double-stranded DNA (dsDNA)-induced fluorescence quenching of CQDs, and enabled the construction of the CQD_SPDs/Pt⁴⁺ probe for the detection of as few as 10 copies of the MRSA gene (mecA and femA). The sensitivity and specificity of the CQD_SPDs/Pt⁴⁺ probe for MRSA detection in clinical specimens (n = 24) were 94% and 86%, respectively. Our results reveal that the CQD_SPDs/Pt⁴⁺ probe has great potential for the diagnosis of antibiotic-resistant superbugs with high sensitivity, specificity, and agreement.