Interferon gamma (IFN-γ)-sensitive TB aptasensor based on novel chitosan-indium nano-kesterite (χtCITS)-labeled DNA aptamer hairpin technology.

There has been increasing interest in the use of biosensors for diagnosis of infectious diseases such as tuberculosis (TB) due to their simplicity, affordability, and potential for point-of-care application. The incorporation of aptamer molecules and nanomaterials in biosensor fabrication explores the advantages of high-binding affinity and low immunogenicity of aptamers as well as the high surface-to-volume ratio of nanomaterials, for increased aptasensor performance. In this work, we employed a novel microwave-synthesized copper indium tin sulfide (CITS) substituted-kesterite nanomaterial, together with a natural biopolymer (chitosan), for signal amplification and increased loading of aptamer molecules.

Bioanalytical methods encompassing label-free and labeled tuberculosis aptasensors: A review.

The high incidence of tuberculosis (TB) infection is of great concern world-wide. The traditional TB diagnostic techniques are not ideal for TB diagnosis in resource-poor countries. This is due to their high complexity, expensive nature, long time duration, poor sensitivity and specificity, as well as their requirement for sophisticated laboratories with special biosafety conditions.

Alpha-Glucosidase and Alpha-Amylase Inhibitory Activities of Novel Abietane Diterpenes from .

The re-investigation of a methanolic extract of collected from the Cape Floristic Region, South Africa (SA), afforded four new abietane diterpenes, namely 19-acetoxy-12-methoxycarnosic acid (), 3β-acetoxy-7α-methoxyrosmanol (), 19-acetoxy-7α-methoxyrosmanol (), 19-acetoxy-12-methoxy carnosol (), and two known named clinopodiolides A (), and B (), in addition to four known triterpenes, oleanolic, and ursolic acids (, ), 11,12-dehydroursolic acid lactone () and β-amyrin (). The chemical structural elucidation of the isolated compounds was determined on the basis of one and two dimensional nuclear magnetic resonance (1D and 2D NMR), high-resolution mass spectrometry (HRMS), ultra violet (UV), fourier transform infrared (IR), in comparison with literature data. The in vitro bio-evaluation against alpha-glucosidase showed strong inhibitory activities of , , and , with the half inhibitory concentration (IC) values of 11.

Electrochemical Screening and Evaluation of Lamiaceae Plant Species from South Africa with Potential Tyrosinase Activity.

South Africa is a country with a wide variety of plants that may contain excellent anti-tyrosinase inhibitors. With wide applications in cosmetics, pharmaceuticals and food products, tyrosinase inhibitors have received very special attention in the recent past as a way of preventing the overproduction of melanin in epidermal layers which often over time brings detrimental effects on human skin. In this present study, a fast screening method using a cyclic voltammetry technique was applied in the evaluation of methanolic extracts of twenty-five species of plants from the Lamiaceae family for anti-tyrosinase activity.

Dendritic copolymer electrode for second harmonic alternating current voltammetric signalling of pyrene in oil-polluted wastewater.

A sensitive dendritic star copolymer-based sensor for pyrene (PY), was developed by in situ electrosynthesis of generation 3 poly(propylene thiophenoimine)-co-poly(3-hexylthiophene) (G3PPT-co-P3HT) on a gold disk electrode (Au). The electrochemical reactivity and the signal transduction properties of the Au|G3PPT-co-P3HT co-polymer electrode were studied by second harmonic alternating current voltammetry (SHACV) and alternating current voltammetry (ACV), respectively. SHACV analysis confirmed the occurrence of Faradaic electrode process (with a standard rate constant, k value of 3.

Label Free Poly(2,5-dimethoxyaniline)-Multi-Walled Carbon Nanotubes Impedimetric Immunosensor for Fumonisin B₁ Detection.

An impedimetric immunosensor for fumonisin B₁ (FB₁) was developed from a poly(2,5-dimethoxyaniline)-multi-walled carbon nanotube (PDMA-MWCNT) composite on the surface of glassy carbon electrode (GCE). The composite was prepared electrochemically and characterized using cyclic voltammetry. The preparation of the FB₁ immunosensor involved the drop-coating of a bovine serum albumin mixture of the anti-fumonisin antibody (anti-Fms) onto the composite polymer-modified GCE.

Electrochemical Interrogation of G3-Poly(propylene thiophenoimine) Dendritic Star Polymer in Phenanthrene Sensing.

A novel dendritic star-copolymer, generation 3 poly(propylene thiophenoimine) (G3PPT)-co-poly(3-hexylthiophene) (P3HT) star co-polymer on gold electrode (i.e., Au|G3PPT-co-P3HT) was used as a sensor system for the determination of phenanthrene (PHE).

Aptameric Recognition-Modulated Electroactivity of Poly(4-Styrenesolfonic Acid)-Doped Polyaniline Films for Single-Shot Detection of Tetrodotoxin.

The work being reported is the first electrochemical sensor for tetrodotoxin (TTX). It was developed on a glassy carbon electrodes (C) that was modified with poly(4-styrenesolfonic acid)-doped polyaniline film (PANI/PSSA). An amine-end functionalized TTX-binding aptamer, 5'-NH₂-AAAAATTTCACACGGGTGCCTCGGCTGTCC-3' (NH₂-Apt), was grafted via covalent glutaraldehyde (glu) cross-linking.

Application on gold nanoparticles-dotted 4-nitrophenylazo graphene in a label-free impedimetric deoxynivalenol immunosensor.

In this paper, we report a new concept to construct a label-free electrochemical inhibition-based immunosensor for the detection of the mycotoxin deoxynivalenol (DON) in cereal samples. The electrochemical impedance spectroscopy of tris(bipyridine) ruthenium (II) chloride was used as a marker enhanced with gold nanoparticles-dotted 4-nitrophenylazo functionalized graphene (AuNp/G/PhNO2) nanocatalyst mediated in Nafion on a glassy carbon electrode. Under the optimized conditions, the formation of immunocomplexes inhibited electron flow and increased the charge transfer resistance of the sensing interface linearly.

Electrochemical aptasensor for endocrine disrupting 17β-estradiol based on a poly(3,4-ethylenedioxylthiopene)-gold nanocomposite platform.

A simple and highly sensitive electrochemical DNA aptasensor with high affinity for endocrine disrupting 17β-estradiol, was developed. Poly(3,4-ethylenedioxylthiophene) (PEDOT) doped with gold nanoparticles (AuNPs) was electrochemically synthesized and employed for the immobilization of biotinylated aptamer towards the detection of the target. The diffusion coefficient of the nanocomposite was 6.

Determination of anthracene on Ag-Au alloy nanoparticles/overoxidized-polypyrrole composite modified glassy carbon electrodes.

A novel electrochemical sensor for the detection of anthracene was prepared by modifying a glassy carbon electrode (GCE) with over-oxidized polypyrrole (PPyox) and Ag-Au (1:3) bimetallic nanoparticles (Ag-AuNPs). The composite electrode (PPyox/Ag-AuNPs/GCE) was prepared by potentiodynamic polymerization of pyrrole on GCE followed by its overoxidation in 0.1 M NaOH.

Electrochemical Immunosensor Based on Polythionine/Gold Nanoparticles for the Determination of Aflatoxin B₁.

An aflatoxin B₁ (AFB₁) electrochemical immunosensor was developed by the immobilisation of aflatoxin B₁-bovine serum albumin (AFB₁-BSA) conjugate on a polythionine (PTH)/gold nanoparticles (AuNP)-modified glassy carbon electrode (GCE). The surface of the AFB₁-BSA conjugate was covered with horseradish peroxidase (HRP), in order to prevent non-specific binding of the immunosensors with ions in the test solution. The AFB₁ immunosensor exhibited a quasi-reversible electrochemistry as indicated by a cyclic voltammetric (CV) peak separation (ΔE) value of 62 mV.

An Electrochemical DNA Biosensor Developed on a Nanocomposite Platform of Gold and Poly(propyleneimine) Dendrimer.

An electrochemical DNA nanobiosensor was prepared by immobilization of a 20mer thiolated probe DNA on electro-deposited generation 4 (G4) poly(propyleneimine) dendrimer (PPI) doped with gold nanoparticles (AuNP) as platform, on a glassy carbon electrode (GCE). Field emission scanning electron microscopy results confirmed the codeposition of PPI (which was linked to the carbon electrode surface by C-N covalent bonds) and AuNP ca 60 nm. Voltammetric interrogations showed that the platform (GCE/PPI-AuNP) was conducting and exhibited reversible electrochemistry (E°' = 235 mV) in pH 7.