Protein-Protected Gold Nanocluster-Based Biosensor for Determining the Prooxidant Activity of Natural Antioxidant Compounds

Abstract

In this work, chicken egg white protein (CEW)-protected gold nanoclusters (CEW-AuNCs) were prepared from CEW and HAuCl 4 to measure the Cu(II)-induced prooxidant activity of antioxidant compounds such as epicatechin, epigallocatechin gallate, catechin, rosmarinic acid, resveratrol, ascorbic acid, and glutathione. These compounds reduced Cu(II) to Cu(I), and the latter was mainly bound to thiol groups in the CEW-AuNC structure. As the protein-bound Cu(I) may act as a catalytic center for generating reactive oxygen species, the Cu(II) reducing ability of antioxidants is an indirect measure of their prooxidant potency. The bound Cu(I) may be released with the cuprous-selective ligand neocuproine (Nc), forming the basis of a spectrophotometric method measuring absorbance at 450 nm wavelength of the Cu(I)–Nc chelate. The developed method involved a one-pot synthesis and determination without preseparation and was applied to binary synthetic mixtures of studied antioxidant compounds and to certain herbal plant (green tea, linden, echinacea, and artichoke leaf) extracts to determine the total prooxidant activities. The obtained results were statistically compared with those of the literature Cu(II)–Nc assay using a calcium proteinate-based solid biosensor. The developed biosensor was durable, reliable, easily applicable, and of low cost and wide linear range and could determine the prooxidant activities of natural antioxidant samples with high reproducibility.

One‒pot green synthesized protein‒based silver nanocluster as prooxidant biosensor

“…This study was the green synthesized method using chicken egg white proteins that was carried out with slight changes in the synthesis method of our previous study [20] and…”

“…DNPH reagent was prepared in 0.2 N HCl solution. Two grams amount of fresh apple and grape were extracted using the microwave-assisted extraction technique as described in our previous study after all samples were washed with water and cut into small pieces with plastic knife [20]. Fruit juices and wine samples were diluted with distilled water and applied the proposed assay directly.…”

“…Silver nanoclusters were prepared after slight modifications as described in our previous study [20]. Briefly, protein solution (50 mL, mg mL -1 ) was added to AgNO3 solution (50 mL, 2.5 mM) and vortexed for 2 minutes before the addiction of NaOH solution (12.5 mL, 5.0 N).…”

“…Existing assays in the literature are expensive especially in detecting radicals by Electron Spin Resonance (ESR) spectroscopy, laborious, limited with respect to application area, and cause positive errors in results because of interferences, likewise in protein carbonyl assay. In our previous studies, we have developed new methods to overcome these disadvantages in the literature with the needs of this research area [18][19][20][21][22].…”

Ultrasmall Au and Ag Nanoclusters for Biomedical Applications: A Review

“… Hossein-Nejad-Ariani et al (2018) developed a peptide-capped Au-NCs-based biosensor for the detection of Listeria monocytogenes, which is portable, simple, fast, and can be operated by non-experts. Akyüz et al (2019) fabricated chicken egg white protein capped Au NCs as a biosensor, which was able to determine the pro-oxidant activity of natural antioxidant compounds. Electrochemiluminescence (ECL) is another type of chemiluminescence, and the Au NCs hold the ECL properties that are not available from Au NPs ( Wang et al, 2016 ; Chen et al, 2019 ).…”