Carbon dot-graphene oxide-based luminescent nanosensor for creatinine detection in human urine

A fluorescence (FL)-based nanosensor has been devised for creatinine (CR) detection in human urine specimens. The proposed nanosensor utilized a nanocomposite (NC) of carbon dots (CDs) and graphene oxide (GO). The formation of CDs/GO NC reduced the CD FL emission (λ_excitation = 390 nm, λ_emission = 461 nm) by ~ 75%. With the introduction of CR to the NC, the CD emission intensity was reinstated by approximately 70%. The linear detection range for CR was 10^-5 to 0.1 mg dL^-1 (R² = 0.998), with a limit of detection of 4.3 × 10^-2 mg dL^-1. Additionally, CDs/GO NC exhibited outstanding consistency and specificity in recognizing CR within urine specimens from both healthy individuals and patients suffering from chronic kidney disease (CKD). The Bland-Altman assessment (utilizing 25 human urine specimens) displayed remarkable consensus (R² = 0.995) among the FL approach and the benchmark Jaffe technique. This observation indicates the hands-on usefulness of the nanosensor for identifying CR in biological specimens.