Encapsulation Capacity of β-Cyclodextrin Stabilized Silver Nanoparticles towards Creatinine Enhances the Colorimetric Sensing of Hydrogen Peroxide in Urine

The β-cyclodextrin shell of synthesized silver nanoparticles (βCD-AgNPs) are found to enhance the detection of hydrogen peroxide in urine when compared to the Horse Radish Peroxidase assay kit. Nanoparticles are confirmed by the UV-Vis absorbance of their localized surface plasmonic resonance (LSPR) at 384 nm. The mean size of the βCD-AgNPs is 53 nm/diameter; XRD analysis shows a face-centered cubic structure. The crystalline structure of type 4H hexagonal nature of the AgNPs with 2.4 nm β-CD coating onto is confirmed using aberration corrected high-resolution transmission electron microscopy (HRTEM). A silver atomic lattice at 2.50 Å and 2.41 Å corresponding to (100) and (101) Miller indices is confirmed using the HRTEM. The scope of βCD-AgNPs to detect hydrogen peroxide (H₂O₂) in aqueous media and human urine is investigated. The test is optimized by examining the effect of volumes of nanoparticles, the pH of the medium, and the kinetic and temperature effect on H₂O₂ detection. The βCD-AgNPs test is used as a refined protocol, which demonstrated improved sensitivity towards H₂O₂ in urine compared to the values obtained by the Horse Radish Assay kit. Direct assessment of H₂O₂ by the βCD-AgNPs test presented always with a linear response in the nM, μM, and mM ranges with a limit of detection of 1.47 nM and a quantitation limit of 3.76 nM. While a linear response obtained from 1.3 to 37.3 nmoles of H₂O₂/mole creatinine with a slope of 0.0075 and regression coefficient of 0.9955 when the βCD-AgNPs is used as refined test of creatinine. Values ranging from 34.62 ± 0.23 nmoles of H₂O₂/mole of creatinine and 54.61 ± 1.04 nmoles of H₂O₂/mole of creatinine when the matrix is not diluted and between 32.16 ± 0.42 nmoles of H₂O₂/mole of creatinine and 49.66 ± 0.80 nmoles of H₂O₂/mole of creatinine when the matrix is twice diluted are found in freshly voided urine of seven apparent healthy men aged between 20 and 40 years old.