Visual and colorimetric determination of H2O2 and glucose based on citrate-promoted H2O2 sculpturing of silver nanoparticles

Abstract

Isotropic silver nanoparticles (iAg NPs) can be easily prepared at low costs, have a low electrochemical potential and high extinction coefficient. An effective colorimetric assay for HO is reported here based on the finding that HO can induce the shape transformation of citrate-capped iAg NPs with the help of citrate. The substantial shape variation affords an apparent surface plasmon resonance (SPR) shift, accompanied by a vivid color change from light yellow to mauve. The color change can be observed visually if the concentration of HO is 2 μM or higher. A good linear relationship was obtained over the concentration range of 0.2-32 μM with a limit of detection of 90 nM. By making use of glucose oxidase, the method is further extended to glucose detection. Glucose at a concentration as low as 10 μM can be well determined with bare eyes. Benefitting from the high selectivity, the detection of glucose in human serum is realized, and the results are in good agreement with those provided by a clinical analyzer. Graphical abstract Schematic presentation of a colorimetric assay for HO and glucose based on citrate-promoted HO-mediated shape transformation of the isotropic silver nanoparticles (Ag NPs). The shape variation of isotropic Ag NPs induces a color change from light yellow to mauve.

Glucose Sensor Using Redox Active Oligonucleotide-Templated Silver Nanoclusters

“…However, the findings of this study suggest that these two peaks might be caused by different oxidation states, with no size change. A number of groups who used NC/NPs as glucose sensors saw an irreversible PL/absorbance shift or quenching caused by NC/NPs agglomeration or disintegration [20,23,30,31]. In contrast, the Ag NCs in this study had a reversible PL change, which is advantageous for use as a cheaper, reusable sensor.…”

“…The response was similar to measurements using glucose in water. It was assumed that GOx was specific for glucose over other blood components due to measurements by Zong et al that had already shown this specificity [20].…”

“…The procedure was adapted from Zong et al for glucose sensing with Ag NPs [20]. Glucose (0–20 mM; 50 µL) and GOx (200 µL, 16.3314 mg·mL −1 , 15 000 U·g −1 , in pH 5.42, 50 mM NaOAc) were combined in a 96-well plate and incubated (~50 min, RT) to allow H 2 O 2 production without Ag NCs because Ag + is known to interfere with GOx activity [33].…”

“…In other systems, the H 2 O 2 oxidises a dye or nanomaterial to show a proportional change to the amount of glucose present [18,19]. Ag and Au nanoparticles/nanoclusters (NPs/NCs) used in this process have typically had irreversible changes, such as aggregation or etching [20]. This was seen with Ag NPs immobilised with GOx in a hydrogel.…”

Phytosynthesis of Palladium Nanoclusters: An Efficient Nanozyme for Ultrasensitive and Selective Detection of Reactive Oxygen Species

“…The biosynthesized nanoclusters exhibited ultrasensitive and selective detection of H 2 O 2 . The novelty of the reported method for the detection of H 2 O 2 , in comparison with previously reported methods, is presented in a tabulated form in Table 1 [20][21][22][23][24][25][26][27][28][29][30][31][32][33]. The biosynthesis of palladium nanoclusters in itself is a novel achievement, and no reports are available on the use of biological methods for this purpose.…”