Abstract
This paper reports the synthesis of positively charged gold nanoparticles [(+)AuNPs] for the colorimetric detection of hydrogen peroxide (H2O2). (+)AuNPs were synthesized using an electrochemically active biofilm in an aqueous solution, which is a novel, simple, and green approach. The as-synthesized (+)AuNPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). UV-Vis spectroscopy confirmed the synthesis of AuNPs and DLS showed that the as-synthesized AuNPs had a charge of +32.72 mV. XRD confirmed the formation of AuNPs as well as the purity, crystallinity, and fcc structure. TEM and HRTEM showed that (+)AuNPs were 15–21 nm in size and spherical in shape. The as-synthesized (+)AuNPs were used for the colorimetric detection of H2O2 using 3,3,5,5-tetramethylbenzidine dihydrochoride. This study provides a simple, fast, and sensitive colorimetric method for the detection of H2O2 in the linear range from 1.0 × 10−3 to 2.5 × 10−3 M. The (+)AuNPs possessed extraordinary intrinsic peroxidase-like activity (peroxidase mimic) compared to citrate-capped negatively charged AuNPs. This approach to the colorimetric detection of H2O2 is novel and simple because it uses positively charged gold nanoparticles, which may provide new areas for further research.
Highlights
Over the last decade, gold nanoparticles (AuNPs) are in prodigious demand by researchers in several fields
This paper reports the extension of a previous study, in which the biogenic extracellular synthesis of positively charged gold nanoparticles [(+)AuNPs] using an electrochemically active biofilm (EAB) was performed in an aqueous solution, which is a novel, simple, and green approach [23]
Taking the advantage of these two phenomena exhibited by the EAB and stainless steel, these two principles were combined as an EAB on stainless steel mesh
Summary
Gold nanoparticles (AuNPs) are in prodigious demand by researchers in several fields. Positively charged gold nanoparticles [(+)AuNPs] have attracted considerable attention for their potential use in biotechnology and biological mimicking [20]. There are few reports on the synthesis of positively charged AuNPs. In most cases, positively charged gold nanoparticles were synthesized by coating or capping [21, 22]. This paper reports the extension of a previous study, in which the biogenic extracellular synthesis of positively charged gold nanoparticles [(+)AuNPs] using an electrochemically active biofilm (EAB) was performed in an aqueous solution, which is a novel, simple, and green approach [23]. The as-synthesized AuNPs showed a high positive charge, which plays an important role in its catalytic activity. The high positive charge (+ 32.72 mV) of the AuNPs highlight its potential use in colorimetric assays.
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