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.