Construction of a novel electrochemical biosensor based on a mesoporous silica/oriented graphene oxide planar electrode for detecting hydrogen peroxide

A new strategy to build electrochemical enzymatic biosensors using a nanohybrid material based on carbon nanotubes and a rationally designed schiff base containing boronic acid

We report a nanohybrid material obtained by non-covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with the new ligand (((1E,1'E)-(naphthalene-2,3-diylbis(azaneylylidene))bis(methaneylylidenedene)) bis(4-hydroxy-3,1-phenylene))diboronic acid (SB-dBA), rationally designed to mimic some recognition properties of biomolecules like concanavalin A, for the development of electrochemical biosensors based on the use of glycobiomolecules as biorecognition element. We present, as a proof-of-concept, a hydrogen peroxide biosensor obtained by anchoring horseradish peroxidase (HRP) at a glassy carbon electrode (GCE) modified with the nanohybrid prepared by sonication of 2.0 mg mL-1 MWCNTs and 0.50 mg mL-1 SB-dBA in N,N-dimethyl formamide (DMF) for 30 min. The hydrogen peroxide biosensing was performed at -0.050 V in the presence of 5.0 × 10-4 M hydroquinone. The analytical characteristics of the resulting biosensor are the following: linear range between 0.175 μM and 6.12 μM, detection limit of 58 nM, and reproducibility of 2.0 % using the same nanohybrid (6 biosensors), and 9.0 % using three different nanohybrids. The sensor was successfully used to quantify hydrogen peroxide in enriched milk and human blood serum samples and in a commercial disinfector.

Synergistic integration of Ni-metal organic framework/SnS2nanocomposite and nickel foam electrode for ultrasensitive and selective electrochemical detection of albumin in simulated human blood serum

Albumin is a vital blood protein responsible for transporting metabolites and drugs throughout the body and serves as a potential biomarker for various medical conditions, including inflammatory, cardiovascular, and renal issues. This report details the fabrication of Ni-metal organic framework/SnS2nanocomposite modified nickel foam electrochemical sensor for highly sensitive and selective non enzymatic detection of albumin in simulated human blood serum samples. Ni-metal organic framework/SnS2nanocomposite was synthesized using solvothermal technique by combining Ni-metal-organic framework (MOF) with conductive SnS2leading to the formation of a highly porous material with reduced toxicity and excellent electrical conductivity. Detailed surface morphology and chemical bonding of the Ni-MOF/SnS2nanocomposite was studied using scanning electron microscopy, transmission electron microscopy, Fourier transform infra-red, and Raman analysis. The Ni-MOF/SnS2nanocomposite coated on Ni foam electrode demonstrated outstanding electrochemical performance, with a low limit of detection (0.44μM) and high sensitivity (1.3μA/pM/cm2) throughout a broad linear range (100 pM-10 mM). The remarkable sensor performance is achieved through the synthesis of a Ni-MOF/SnS2nanocomposite, enhancing electrocatalytic activity for efficient albumin redox reactions. The enhanced performance can be attributed due to the structural porosity of nickel foam and Ni-metal organic framework, which favours increased surface area for albumin interaction. The presence of SnS2shows stability in acidic and neutral solutions due to high surface to volume ratio which in turn improves sensitivity of the sensing material. The sensor exhibited commendable selectivity, maintaining its performance even when exposed to potential interfering substances like glucose, ascorbic acid, K+, Na+, uric acid, and urea. The sensor effectively demonstrates its accuracy in detecting albumin in real samples, showcasing substantial recovery percentages of 105.1%, 110.28%, and 91.16%.

Synthesis of nanoscale zero-valent iron doped carbonized zeolitic imidazolate framework-8 for methylene blue removal in water

Nanoscale zero-valent iron-doped carbonized zeolitic imidazolate framework-8 (nZVI/CZIF-8) was prepared by carbonation of ferric nitrate and ZIF-8 at 800 °C and used as an adsorbent to remove methylene blue (MB) from water. The synthesized nZVI/CZIF-8 has a specific surface area of 806.9 m2/g, a pore volume of 0.86 cm3/g and an nZVI content of 1.35%, respectively. Both the nZVI/CZIF-8 and CZIF-8 have identical functional groups of O-H, C-H and C=C. With the increase of CZIF-8 size, MB removal rate increased. The doping of nZVI increased the MB removal percentage from 74.5% for ZIF-8 to 96.2% within 80 min for nZVI/CZIF-8. The MB removal percentage increased with the dosage of nZVI/CZIF-8. The MB adsorption with the adsorbents conforms to the Freundlich adsorption isothermal model and the removal rate fitted well to a pseudo-first-order model. The results demonstrate the feasibility of synthesizing high active and stable nZVI/CZIF-8 particles.

Peptide Nanosheet-Inspired Biomimetic Synthesis of CuS Nanoparticles on Ti3C2 Nanosheets for Electrochemical Biosensing of Hydrogen Peroxide

Hydrogen peroxide (H₂O₂) is one of the intermediates or final products of biological metabolism and participates in many important biological processes of life activities. The detection of H₂O₂ is of great significance in clinical disease monitoring, environmental protection, and bioanalysis. In this study, Ti₃C₂-based nanohybrids are prepared by the biological modification and self-assembled peptide nanosheets (PNSs)-based biomimetic synthesis of copper sulfide nanoparticles (CuS NPs), which show potential application in the fabrication of low-cost and high-performance electrochemical H₂O₂ biosensors. The synthesized CuS-PNSs/Ti₃C₂ nanohybrids exhibit excellent electrochemical performance towards H₂O₂, in which CuS NPs can catalyze the decomposition of H₂O₂ and realize the transformation from a chemical signal to an electrical signal to achieve the purpose of H₂O₂ detection. The prepared CuS-PNSs/Ti₃C₂-based electrochemical biosensor platform exhibits a wide detection range (5 μM-15 mM) and a low detection limit (0.226 μM). In addition, it reveals good selectivity and stability and can realize the monitoring of H₂O₂ in a complex environment. The successful biomimetic synthesis of CuS-PNSs/Ti₃C₂ hybrid nanomaterials provides a green and friendly strategy for the design and synthesis of functional nanomaterials and also provides a new inspiration for the construction of highly effective electrochemical biosensors for practical detection of H₂O₂ in various environments.

Biosensor based on bimetallic/graphene composite for non-enzymatic detection of hydrogen peroxide in living tumor cells

A highly sensitive electrochemical biosensor was manufactured with triple synergistic catalysis to detect hydrogen peroxide (H₂ O₂ ). In this study, a highly sensitive biosensor based on Prussian blue-chitosan/graphene-hemin nanomaterial/platinum and palladium nanoparticles (PB-CS/HGNs/Pt&Pd biosensor) was fabricated for the detection of H₂ O₂ . The materials described above were modified on the electrode surface and applied to catalyze the breakdown of hydrogen peroxide. The current response of the biosensor presented a linear relationship with H₂ O₂ concentration from 6 × 10^-2 to 20 μM (R² = 0.9766) and with the logarithm of H₂ O₂ concentration from 20 to 9×10³  μM (R² = 0.9782), the low detection limit of 25 nM was obtained at the signal/noise (S/N) ratio of 3. Besides, the biosensor showed an outstanding anti-interference ability and acceptable reproducibility. PB-CS/HGNs/Pt&Pd electrodes are effective in measuring H₂ O₂ from living tumor cells, which implies that the biosensor has the potential to assess reactive oxygen species in various living tumor cells.

Biomimetic graphene-supported ultrafine platinum nanowires for colorimetric and electrochemical detection of hydrogen peroxide

The detection of hydrogen peroxide (H₂O₂) is of great significance in environmental monitoring, enzymatic reactions, and disease diagnosis. Here we present the peptide-mediated biomimetic synthesis of ultrafine platinum nanowires (PtNWs) on graphene oxide (GO) nanosheets for the formation of functional hybrids, which show high potential for the fabrication of colorimetric and electrochemical sensors for the detection of H₂O₂ with high performance. A multifunctional peptide with the sequence KIIIIKYWYAF was designed to create peptide nanofibers (PNFs) via a controllable self-assembly process, which serves as a bridge between GO nanosheets and PtNWs to form PtNWs-PNFs/GO hybrids. On this basis, a dual-mode sensor platform for both colorimetric and electrochemical sensing of H₂O₂ was fabricated successfully. The obtained results indicate that the synthesized PtNWs-PNFs/GO hybrids could catalyze the decomposition of H₂O₂ to generate ˙OH radicals with a significant current response, and the ˙OH radicals are capable of overoxidizing 3,3',5,5',-tetramethylbenzidine (TMB), producing a blue-colored species with a distinct color change for colorimetric sensing. In addition, due to its high catalytic activity, the fabricated PtNWs-PNFs/GO hybrid-based electrochemical sensor exhibits a wider linear detection range of 0.05 μM-15 mM and a low detection limit of 0.0206 μM, which can be applied to detect H₂O₂ with high selectivity and sensitivity. Our study provides a green and environmentally friendly synthetic strategy for the preparation of biomimetic materials from PtNWs, and the fabricated colorimetric/electrochemical dual-mode H₂O₂ sensor platform will have a great impact in bioanalysis, environmental monitoring, and biomedicine.

Colorimetric assay based on NiCo2S4@N,S-rGO nanozyme for sensitive detection of H2O2 and glucose in serum and urine samples

Traditional bimetallic sulfide-based nanomaterials often have a small specific surface area (SSA), low dispersion, and poor conductivity, thereby limiting their wide applications in the nanozyme-catalytic field. To address the above issues, we herein integrated NiCo2S4 with N,S-rGO to fabricate a nanocomposite (NiCo2S4@N,S-rGO), which showed a stronger peroxidase-mimetic activity than its pristine components. The SSA (155.8 m2 g-1) of NiCo2S4@N,S-rGO increased by ∼2-fold compared to NiCo2S4 with a pore size of 7-9 nm, thus providing more active sites and charge transfer channels. Based on the Michaelis-Menten equation, the affinity of this nanocomposite increased 40% and 1.1∼10.6-fold compared with NiCo2S4 with N,S-rGO, respectively, highlighting the significant enhancement of the peroxidase-like activity. The enhanced activity of this nanocomposite is derived from the joint participation of ˙OH, ˙O2 -, and photogenerated holes (h+), and was dominated by h+. To sum up, N,S-codoping, rich S-vacancies, and multi-valence states for this nanocomposite facilitate electron transfer and accelerate reaction processes. The nanocomposite-based colorimetric sensor gave low detection limits for H2O2 (12 μM) and glucose (0.3 μM). In comparison with the results detected by a common glucose meter, this sensor provided the relative recoveries across the range of 97.4-101.8%, demonstrating its high accuracy. Moreover, it exhibited excellent selectivity for glucose assay with little interference from common co-existing macromolecules/ions, as well as high reusability (>6 times). Collectively, the newly developed colorimetric sensor yields a promising methodology for practical applications in H2O2 and glucose detection with advantages of highly visual resolution, simple operation, convenient use, and satisfactory sensitivity.

Three-dimensional gold nanowires with high specific surface area for simultaneous detection of heavy metal ions

Traditional detection methods to detect heavy metal ions are time-consuming, complicated, and expensive. Here, we developed a simple electroless plating method to prepare three-dimensional gold nanowire (Au NW) films with high specific surface area. In an aqueous plating bath, tetrachloroauric acid, 4-dimethylaminopyridine and formaldehyde are used as precursor, ligand, and reducing agent, respectively. An electrochemical sensor based on a Au NWs/SPE could be applied for simultaneous detection of lead (Pb(II)), arsenic (As(III)), and mercury (Hg(II)) ions. The detection limits of Pb(II), As(III), and Hg(II) are 2.6, 1.5, and 4.2 μg L^-1, all lower than the permissible limits of the WHO for drinking water (the permissible level of Pb(II) and As(III) is 10.0 μg L^-1, and the permissible level of Hg(II) is 6.0 μg L^-1), respectively. This work presents a simple and novel method to prepare gold nanowires for quick detection of trace heavy metal ions.