EDTA-capped silver nanoparticles as a probe for highly sensitive and selective colorimetric sensing of creatinine and optimization using response surface methodology-Box Behnken Design

Creatinine concentration is an essential indicator for assessing kidney function and diagnosing a disease. A selective and sensitive colorimetric detection was developed based on the EDTA-capped AgNPs aggregation to determine creatinine accurately. The developed method was optimized using response surface methodology (RSM) with Box-Behnken Design (BBD) model by studying pH, AgNPs concentration, and detection time as the critical parameters. The result showed that medium pH had the most crucial role in the interaction between EDTA-capped AgNPs and creatinine. The addition of creatinine to the colloidal EDTA-capped AgNPs induced the particle aggregation, followed by a color change from yellow (with lambda max 398 nm) to dark blue (with lambda max 650 nm) within 1 min of reaction at pH 12. The tautomerization of creatinine to its anionic amino species at alkaline pH, which cross-links the EDTA-capped AgNPs through the hydrogen bond networks with the negatively charged EDTA-capped AgNPs, occurs via an aggregation mechanism. The SPR absorbance ratio of A₆₅₀/A₃₉₈ was correlated to the creatinine concentration under the optimized conditions in the range of 0.0–3.0 μM with the limit of detection (LOD) of 0.0073 µM. The proposed method could offer simple, rapid, and inexpensive creatinine analysis for clinical diagnosis.