Synthesis of tunable size gold nanoparticles using seeding growth method and its application in glucose sensor

Abstract

This work describes synthesis of gold nanoparticles (AuNPs) of tunable size using the seeding growth method. High concentration of AuNPs of various sizes was synthesized by varying synthesis parameters. The properties were observed using transmission electron microscope (TEM), zetasizernanoZS, X-ray diffractometer (XRD) and UV Vis spectrophotometers. The produced AuNPs were then used in fabrication of glucose sensors with the following structure; Nafion/GOx/AuNPs/ITO. The effect of AuNPs size on glucose sensor properties was studied by measuring electrocatalytic activity of the prepared AuNPs/ITO electrodes using cyclic voltammetry in the range of -0.5 to 0.5 V versus Ag/AgCl reference electrode. Cyclic voltammograms of various sizes of AuNPs tested in 10 mM glucose in 0.01 M PBS. UV-Vis analysis shows the wavelength of AuNPs increases from 518, 519, 523, 525 and 529 for 15 (Au seed), 20, 30, 40 and 50 nm, respectively. Particle size analysis using the zetasizer gave z-average for expected size 20, 30, 40 and 50 nm AuNPs of 29.97, 42.61, 44.16 and 58.78 nm, respectively. All of the z-average is larger than the size expected. The polydispersity index (PDI) for size 20, 30, 40 and 50 nm AuNPs are 0.372, 0.096, 0.112 and 0.102, respectively. XRD analysis matched with (111), (200), (220) and (311) face centered cubic Au planes (ICDD 98-005-0876). The result confirmed that AuNPs is in crystalline structure. For glucose sensor, 30 nm AuNPs has the highest electrocatalytic activity as it has the highest anodic and cathodic peak currents compared to other size of AuNPs. The results obtained could be caused by low PDI value measured using zeta-sizer and the uniform particles size distribution as observed in TEM images.This work describes synthesis of gold nanoparticles (AuNPs) of tunable size using the seeding growth method. High concentration of AuNPs of various sizes was synthesized by varying synthesis parameters. The properties were observed using transmission electron microscope (TEM), zetasizernanoZS, X-ray diffractometer (XRD) and UV Vis spectrophotometers. The produced AuNPs were then used in fabrication of glucose sensors with the following structure; Nafion/GOx/AuNPs/ITO. The effect of AuNPs size on glucose sensor properties was studied by measuring electrocatalytic activity of the prepared AuNPs/ITO electrodes using cyclic voltammetry in the range of -0.5 to 0.5 V versus Ag/AgCl reference electrode. Cyclic voltammograms of various sizes of AuNPs tested in 10 mM glucose in 0.01 M PBS. UV-Vis analysis shows the wavelength of AuNPs increases from 518, 519, 523, 525 and 529 for 15 (Au seed), 20, 30, 40 and 50 nm, respectively. Particle size analysis using the zetasizer gave z-average for expected size 20, 30, 40...