Protein capped Cu nanoclusters-SWCNT nanocomposite as a novel candidate of high performance platform for organophosphates enzymeless biosensor

An electrochemical biosensor based on hemoglobin-oligonucleotides-modified electrode for detection of acrylamide in potato fries

Acrylamide a neurotoxin and strong carcinogen, is found in various thermally processed foods. In this study, an electrochemical sensor for detection of acrylamide using double stranded DNA (dsDNA)/Hemoglobin (Hb)-modified screen printed gold electrode (SPGE) was designed. The immobilization of ssDNA1-SH on the surface of SPGE was confirmed by cyclic voltammetry, and the interaction between ssDNA2-NH₂ and Hb with the ratio 1:1 was characterized by agarose gel. The excellent response of the designed biosensor towards acrylamide due to acrylamide and Hb adducts and change of reduction/oxidation process of Hb-Fe(III)/Hb-Fe(II) was determined by square wave voltammetry (SWV). The biosensor showed the optimum response at pH 8.0. The linear working range for acrylamide was from 2.0 × 10^-6 to 5.0 × 10^-2 M with a detection limit of 1.58 × 10^-7 M. The biosensor was suitable for direct determination of acrylamide in water extracted of potato fries and displayed good reproductivity and high stability.

Rapid Determination of H2S Poisoning in a Forensic Study Using a Novel Fluorescence Assay Based on Zn/Cu@BSA Nanoclusters

The quantitative determination of H2S in the blood can provide valid evidence for H2S poisoning through occupational exposure. However, known traditional methods for the detection of H2S in blood are time consuming, require complicated pretreatments, and have low sensitivity. In this paper, a new fluorescence sensing assay is proposed for the rapid detection of H2S poisoning in forensic cases based on bovine serum albumin (BSA)-stabilised zinc/copper (Zn/Cu) bi-metal nanoclusters (Zn/Cu@BSA NCs). The as-prepared Zn/Cu@BSA NCs probes have been characterised by UV-vis absorption and fluorescence spectroscopy. The fluorescence of Zn/Cu@BSA NCs can be quenched through specific interactions between HS−/S2− and the Zn2+/Cu2+ bi-metal ions. Under optimised conditions, the fluorescence sensing method was linear in the concentration range of 2.5 nM to 30 mM with 0.69 nM as the limit of detection. Moreover, the practical feasibility of this fluorescence sensing method has also been demonstrated by the analysis of mice blood samples containing different levels of sulfide and human blood samples from forensic cases of H2S poisoning. Compared with gas chromatography/mass spectrometry (GC/MS), this fluorescence sensing method is quite simple, straightforward, and can be accurate for the quantitative determination of H2S poisoning in a few minutes for forensic analysis. Overall, this is the first report of a bi-metal fluorescence sensing assay for detecting H2S poisoning directly in blood. This research may provide a new approach for forensic toxicologists to monitor poisoning by H2S using a fluorescence-sensing method.

A novel and high performance enzyme-less sensing layer for electrochemical detection of methyl parathion based on BSA templated Au–Ag bimetallic nanoclusters

In the present manuscript, a modified glassy carbon electrode with BSA templated Au–Ag bimetallic nanoclusters (Au–Ag@BSA/GCE) was employed for the rapid, selective and sensitive determination of methyl parathion (MP) as an enzyme-less electrochemical biosensor.

Trace level electrochemical determination of the neurotransmitter dopamine in biological samples based on iron oxide nanoparticle decorated graphene sheets

The trace level electrochemical determination of dopamine in biological samples based on an iron oxide nanoparticle-capped graphene sheet modified electrode.

Graphene nanoribbon/FePt bimetallic nanoparticles/uric acid as a novel magnetic sensing layer of screen printed electrode for sensitive determination of ampyra

A novel electrochemical sensor for sensitive determination of ampyra (Am) based on graphene nanoribbons modified by iron-platinum bimetallic nanoparticles and uric acid (SPCE/FePtGNR/UA) dropped on the screen-printed carbon electrode (SPCE) surface and magnetically captured onto an SPCE working electrode surface is reported in the present work. The modified nanocomposite and sensing layer was characterized by different techniques, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray powdered diffraction (XRD). Am determination by conventional electrochemical methods is not possible, because of its high redox overpotential. Therefore, the differential pulse voltammetry (DPV) signals of UA were used as a redox probe for indirect electrochemical determination of Am. The limit of detection (LOD) and linear concentration range were obtained as 0.028 and 0.08-9.0µmolL^-1 (3S_b/m = 3), respectively. The feasibility of the proposed method was examined by the detection of Am in biological and pharmaceutical samples with satisfactory results. The constructed electrochemical sensor was applied for fast, simple and sensitive detection of Am in real environments.

Electrochemical biosensing based on protein-directed carbon nanospheres embedded with SnOx and TiO2 nanocrystals for sensitive detection of tobramycin

A series of nanocomposites comprised of homogeneous mesoporous carbon nanospheres embedded with SnO_x (x = 0, 1, or 2) and TiO₂ nanocrystals using bovine serum albumin (BSA) as template followed by calcinated at different temperatures (300, 500, 700, and 900°C) were prepared, and were denoted as SnO_x@TiO₂@mC. Then a novel electrochemical biosensing strategy for detecting tobramycin (TOB) based on the nanocomposites was constructed. The as-prepared SnO_x@TiO₂@mC nanocomposites not only possess high specific surface area and good electrochemical activity but also exhibit strong bioaffinity with the aptamer strands, therefore, they were applied as the scaffold for anchoring TOB-targeted aptamer and further used to sensitively detect trace TOB in aqueous solutions. By comparing the electrochemical biosensing responses toward TOB detection based on the four SnO_x@TiO₂@mC nanocomposites, the biosensing system constructed with SnO_x@TiO₂@mC₉₀₀ (derived at 900°C) demonstrated the highest determination efficiency, high selectivity, and good stability. In particular, the new proposed aptasensing method based on SnO_x@TiO₂@mC nanocomposite exhibits considerable potential for the quantitative detection of TOB in the biomedical field.

Fabrication of a Novel Highly Sensitive and Selective Immunosensor for Botulinum Neurotoxin Serotype A Based on an Effective Platform of Electrosynthesized Gold Nanodendrites/Chitosan Nanoparticles

In this work, a novel nanocomposite consisting of electrosynthesized gold nanodendrites and chitosan nanoparticles (AuNDs/CSNPs) has been prepared to fabricate an impedimetric immunosensor based on a screen printed carbon electrode (SPCE) for the rapid and sensitive immunoassay of botulinum neurotoxin A (BoNT/A). BoNT/A polyclonal antibody was immobilized on the nanocomposite-modified SPCE for the signal amplification. The structure of the prepared nanocomposite was investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The charge transfer resistance (R_CT) changes were used to detect BoNT/A as the specific immuno-interactions at the immunosensor surface that efficiently limited the electron transfer of Fe(CN)₆^3−/4− as a redox probe at pH = 7.4. A linear relationship was observed between the %∆R_CT and the concentration logarithm of BoNT/A within the range of 0.2 to 230 pg·mL⁻¹ with a detection limit (S/N = 3) of 0.15 pg·mL⁻¹. The practical applicability of the proposed sensor was examined by evaluating the detection of BoNT/A in milk and serum samples with satisfactory recoveries. Therefore, the prepared immunosensor holds great promise for the fast, simple and sensitive detection of BoNT/A in various real samples.

Sensitive electrochemical determination of rifampicin using gold nanoparticles/poly-melamine nanocomposite

Green and facile method for fabrication of a conductive polymer–Au nanocomposite platform as a novel electrochemical sensing layer for rifampicin.