Highly sensitive and simple colorimetric assay of hydrogen peroxide and glucose in human serum via the smart synergistic catalytic mechanism

ZnO nanorods grown on Cu wire mesh provide a high sensitivity non-enzymatic absorbance glucose sensor

A highly sensitive non-enzymatic absorption-based glucose sensor is introduced that combines ZnO nanorods with the ferrous oxidation-xylenol orange (FOX) assay. ZnO nanorods were successfully synthesized on the surface of a copper wire mesh, exhibiting high crystallinity, purity, and a large surface area. The glucose sensor displays a high sensitivity of 0.394 mM-1 in a wide linear detection range (0 - 6 mM), along with a low limit of detection of 0.25 mM. The proposed assay has an excellent selectivity towards glucose compared with other sugars such as sucrose, maltose, and fructose. The potential use of the non-enzymatic absorbance sensor for diabetes monitoring is demonstrated by measuring the glucose concentration in human blood serum, obtaining values that are consistent with clinical analysis.

Research Progress of SERS Sensors Based on Hydrogen Peroxide and Related Substances

Hydrogen peroxide (H2O2) has an important role in living organisms, and its detection is of great importance in medical, chemical, and food safety applications. This review provides a comparison of different types of Surface-enhanced Raman scattering (SERS) sensors for H2O2 and related substances with respect to their detection limits, which are of interest due to high sensitivity compared to conventional sensors. According to the latest research report, this review focuses on the sensing mechanism of different sensors and summarizes the linear range, detection limits, and cellular applications of new SERS sensors, and discusses the limitations in vivo and future prospects of SERS technology for the detection of H2O2.

Ultrafast colorimetric detection of Cr(VI) based on competition of 8-HQ to Cr(VI) and TMB oxides using GO/AuNPs nanocomposites as peroxidase mimic

Rapid detection of ultra-trace heavy metal chromium is very important for ecological environment. Herein, a rapid colorimetric assay was constructed for detecting hexavalent chromium (Cr(VI)) in environment water through the strong peroxidase mimicking activity of graphene oxide/gold nanoparticles (GO/AuNPs) nanocomposites and competition of Cr(VI) to 3,3',5,5'-tetramethylbenzidine (TMB) oxides and 8-hydroxyquinoline (8-HQ). Cr(VI) could effectively prevent the reaction between 8-HQ and TMB oxides to restore the blue color of the system. The detection limit for Cr(VI) was as low as0.018 µM by spectroscopic absorption. Paper-based colorimetric analysis had the detection limit of0.153 µM. The high sensitivity was basically due to the strong peroxidase mimicking activity of GO/AuNPs nanocomposite from synergistic coupling action and the firm chelation between 8-HQ and Cr(VI) from inner-sphere surface complexation. The detection results for real water sample showed that the analysis had feasibility in practical application. It is worth mentioning that the assay is performed by one-step mixing mode at room temperature, and a single test can be completed in half a minute. Indeed, this work not only provided an extremely easy method for real-time detecting Cr(VI) in the environment, but also verified the vitality of colorimetric strategy based on the strong peroxidase mimicking activity and competitive reaction.

NIR-II driven photocatalytic hydrogen peroxide-supply on metallic copper-nickel selenide (Cu-Ni0.85Se) nanoparticle for synergistic therapy

Currently, finite intratumoral H₂O₂ content has restricted the efficacy of chemodynamic therapy (CDT). Here, Cu-Ni_0.85Se@PEG nanoparticles are constructed to display intracellular NIR-II photocatalytic H₂O₂ supplement. The formation mechanism is explored to discover that H₂O₂ generation is dominated by photo-excited electrons and dissolved O₂ via a typical sequential single-electron transfer process. Both density functional theory calculation and experimental data confirm its metallic feature that endows the great NIR-II absorption and photothermal conversion efficiency (59.6 %, 1064 nm). Furthermore, the photothermal-assisting consecutive interband and intraband transition in metallic catalyst contributes to the high redox capacity and efficient separation/transfer ability of photo-generated charges, boosting H₂O₂ production under 1064 nm laser irradiation. In addition, Cu-Ni_0.85Se@PEG possess mimic peroxidase and catalase activity, leading to in-situ H₂O₂ activation to produce ∙OH and O₂ for the enhanced CDT and hypoxia relief. What's more, the nanomaterials reveal novel biodegradation that is derived from oxidation from insolvable selenide into soluble selenate, resulting in elimination via feces and urine within 2 weeks. Synergistic CDT and photothermal therapy (PTT) further lead to great tumor inhibition and immune response for anti-tumor. The antitumor mechanism and the potential biological process also are investigated by high-throughput sequencing of expressed transcripts (RNAseq). The great treatment performance is responsible for the regulation of related oxidative stress and stimulus genes to induce organelle (mitochondrial) and membrane dysfunction. Besides, the synergistic therapy also can efficiently evoke immune response to further fight against tumor.

Decorating Zirconium on Graphene Oxide to Design a Multifunctional Nanozyme for Eco-Friendly Detection of Hydrogen Peroxide

Peroxidase enzymes are crucial in analytical chemistry owing to significant peroxide analytes and their key role in hydrogen peroxide (H2O2) detection. Therefore, exploiting appropriate catalysts for the peroxidase like reactions has become crucial for achieving desired analytical performance. Zirconium (Zr) has attracted growing interest, as a safe and stable potential eco-friendly catalyst for various organic transformations that address increasing environmental challenges. Hence, aiming at fast, sensitive and selective optical detection of H2O2, a colorimetric platform is presented here, based on the excellent peroxidase enzyme-like activity of Zr decorated on graphene oxide (GO). The synergistic effect achieved due to intimate contact between an enzyme like Zr and the high surface area 0f GO ensures efficient electron transfer that increases the chemical and catalytic activity of the composite and advances the decomposition of H2O2 into hydroxyl radicals. The designed probe, thus, efficiently catalyzes the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB), via hydroxyl radicals, thereby transforming the colorless TMB into blue oxidized TMB within 2 min. The catalytic mechanism of the Zr-GO enzyme mimic is proposed herein and verified using a fluorescent probe terephthalic acid (TA) and other scavenger experiments. The multifunctional optical probe allows sensitive and highly selective recognition of H2O2 in a linear range from 100 to 1000 µM with a low detection limit of 0.57 µM. Essentially, the direct accessibility of Zr prevents having to use the complicated preparation and purification procedures mostly practiced for conventional biozymes and nanozymes. The devised method offers several gains, including being green and an inexpensive catalyst, having lower LOD, being fast, cost-effective and sensitive, and having selective work-up procedures.

Determination of Cr(VI) based on the peroxidase mimetic catalytic activity of citrate-capped gold nanoparticles

Highly negatively charged gold nanoparticles (AuNPs) are shown to have strong simulated oxidase activity and effectively boosted the oxidation of enzyme substrate 3,3',5,5'-tetramethylbenzidine (TMB) by hexavalent chromium ion Cr(VI), resulting in the formation of oxidation product with blue color. Based on this, a facile colorimetric assay was developed to detect Cr(VI) at a range 0.008~0.156 mg/L with r = 0.996. The detection limit was estimated to be 0.52 μg/L. In addition, the colorimetric assay showed high selectivity against 28 other interfering ions. It was performed at room temperature and required about half an hour including the preparation of AuNPs. The assay was successfully applied to the determination of Cr(VI) in spiked water samples, and recoveries in the range 95.00-105.40% were obtained. This work paves a way for design of high performance sensor based on highly active nanozymes and also provides an extremely practical analytical tool for the monitoring of Cr(VI) in the environment.

Colorimetric oligonucleotide-based sensor for ultra-low Hg2+ in contaminated environmental medium: Convenience, sensitivity and mechanism

A colorimetric sensor for detection of Hg²⁺ is developed via graphene oxide/gold nanoparticles (GO/AuNPs) nanocomposite as peroxidase mimic. In the absence of Hg²⁺, the adsorption of ss-DNA on GO/AuNPs resulted in the decrease of peroxidase-like activity of GO/AuNPs, which catalyzed the oxidation of 3, 3, 5, 5-tetramethylbenzidine (TMB) to be very light blue. In the presence of Hg²⁺, the oligonucleotides of T-Hg²⁺-T conformation formed by thymine-Hg(II)-thymine interaction could not be adsorbed or bonded on GO/AuNPs, and the GO/AuNPs resumed their original high activity of peroxidase mimic and catalyzed the oxidation of TMB into distinct blue product. Under optimized conditions, the absorbance value at the wavelength of 655 nm (A₆₅₅) was linearly related with the concentration of Hg²⁺ in the range between 5.2 × 10^-9 M and 1.2 × 10^-7 M with a detection limit of 3.8 × 10^-10 M. By visual observation with the naked eye, Hg²⁺ as low as 3.3 × 10^-7 M could cause color change in solution. The specific T-Hg²⁺-T binding made it easy to selectively detect Hg²⁺. The results show that the colorimetric assay offers great potential for the detection of Hg²⁺ in real samples.

Phytochemical Analysis and Antidiabetic Potential of Armoracia Rusticana: Pharmacological and Computational Approach

Aims & Objective: Armoracia rusticana has high medicinal values and is an excellent source of phytochemicals. This study was aimed to evaluate the antidiabetic potential of bioactive compounds from Armoracia rusticana.

METHODS

The antidiabetic analysis revealed that Armoracia rusticana was highly active against α- glucosidase with IC50 values of 5.6 μg/ml. Furthermore, molecular docking was used to identify the active constituents against α-glucosidase, while using acarbose as a controlled drug.

RESULTS

Upon phytochemical screening, it was found that six out of ten phytochemicals were successfully docked in the respective binding sites. The lead phytochemical was Quercetin 3-Obeta- D-xylopyranoside, which displayed a more binding score as compared to acarbose. They were subjected to analyze for drug-like properties, which further strengthen its validation.

CONCLUSION

It was, therefore, concluded that Armoracia rusticana might potentially be used in the amelioration of type 2 diabetes. Potential molecules identified from this study could be considered as a lead drug to cure diabetes mellitus.