Optical sensing of hydrogen peroxide using starch capped silver nanoparticles, synthesis, optimization and detection in urine

Abstract

Silver nanoparticles were synthesized using starch as a capping shell, AgNO3 as a source of silver and sodium borohydride (NaBH4) as a reducing agent. The nanoparticles were confirmed by their localized surface plasmonic resonance (LSPR) Ultraviolet-visible (UV–Vis) absorbance at 403 nm. Dynamic light scattering (DLS) reveals that starch capped silver nanoparticles (SAgNPs) mean size were 4.13 nm/diameter; the structure of SAgNPs was identified as face-centered cubic (FCC) using XRD analysis. HRTEM micrograph and contrast intensity profile confirms Ag atomic lattices at a distance of 2.35 Å and 2.03 Å corresponding to (111) and (200) hkl plane. The scope of SAgNPs to detect hydrogen peroxide (H2O2) in aqueous media and in urine samples was investigated. Volumes of SAgNPs, pH, temperature and time effect were used as parameters to optimize the detection of H2O2. The SAgNPs assay was compared with a commercially available assay kit. Linear responses were obtained with slopes and regression factors of (0.1025; r2=0.9883) and (0.0776; r2=0.9940) for SAgNPs and the assay kit respectively. Limit of detection (LOD) of 3.70 µM was obtained in the 0.45–121 µM range while, a LOD of 10.5 nM was obtained in the 4.70–32.0 nM range for the SAgNPs test. Values in the range of (9.22 ± 0.30 – 17.89 ± 0.28) and (8.43 ± 0.06 – 26.81 ± 0.19) μM of H2O2 were assessed by using SAgNPs and assay kit respectively, in urine samples collected from seven apparently healthy men aged between 20 and 40 years old.