Polyvinyl alcohol-citrate-stabilized silver nanoparticles as an optical sensor for selective colorimetric determination of sildenafil.

A facile and sensitive colorimetric detection method for sildenafil citrate (SLDC) has been developed by using polyvinyl alcohol-citrate-stabilized silver nanoparticles (PVA-Cit-AgNPs). The sensitivity and selectivity of colorimetric detection were investigated in detail. The PVA-Cit-AgNPs could be induced to aggregate immediately in the presence of SLDC, especially after the addition of 0.

Spectrophotometric and colorimetric determination of gallium (III) with p-aminohippuric acid-functionalized citrate capped gold nanoparticles.

A new technique for sensing Ga(III) concentration based on polyvinyl alcohol-citrate capped gold nanoparticle- aminohippuric acid hybrid (or three-layer core-shell configurations) has been demonstrated. The aminohippuric acid capped citrate-gold nanoparticles were comfortably agglomerated in the presence of Ga(III), and the color of the reaction quickly turned from red to violet or blue. Under the detection conditions, a good linear relationship was ideally obtained between the ratio of the absorbance intensity at 620 nm to that at 520 nm (A/A).

Nanotechnology-based Colorimetric Approaches for Pathogenic Virus Sensing: A Review.

Fast and inexpensive virus identification protocols are of paramount value to hinder the increase of pandemic diseases, minimize economic and social damages, and expedite proper clinical rehabilitation. Until now, various biosensors have been developed for the identification of pathogenic particles. But, they offer many limitations.

A Review on Colorimetric Sensing of Tumor Markers Based on Enzyme-Mimicking Nanomaterials.

Nanomedicine is an arising field that exploits nanotechnology concepts for pioneered therapy and diagnostics. Colorimetric sensors for tumor markers have displayed interesting benefits compared to conventional systems in clinical laboratory diagnosis. Colorimetric immunoassay-based approaches show up-and-coming results since the goal cancer marker is determined with high sensitivity but without the utilization of advanced/- expensive techniques through an effortless optical color change.

Electrochemical Immunosensors Based on Nanostructured Materials for Sensing of Prostate-Specific Antigen: A Review.

The prostate-specific antigen (PSA) has been considered a crucial serological marker for distinguishing prostate based cancer. This survey shows recent progress in the construction of nanomaterial-based electrochemical immunosensors for a PSA. This review (from 2015 to 2020) reports the latest progress in PSA sensing based on the employ of different types of nanostructured materials.

Electrochemical and Electrochemiluminescence Dendrimer-based Nanostructured Immunosensors for Tumor Marker Detection: A Review.

The usage of dendrimers or cascade molecules in the biomedical area has recently attracted much attention worldwide. Furthermore, dendrimers are interesting in clinical and pre-clinical applications due to their unique characteristics. Cancer is one of the most widespread challenges and important diseases, which has the highest mortality rate.

Electrochemical immunosensors for the detection of cytokine tumor necrosis factor alpha: A review.

In this review, we focus on recent developments in nonlabeled@label-free and labeled@sandwich assay concepts of tumor necrosis factor-alpha (TNF-α) using numerous electrochemical approaches. The fundamental role of such nanostructured materials for the improvement of the analytical response and thus the analytical figures of merit of various TNF-α sensing operations were revealed. Also, this examination focused on recent developments in immuno-electrochemical cytokine TNF-α sensors based on nanostructured materials from 2006 to 2019.

Magnetic nanostructures for preconcentration, speciation and determination of chromium ions: A review.

Magnetic nanoparticles based solid-phase extraction is a new analytical technique based on the use of magnetic sorbents for the preconcentration and quantification of different inorganic and organic species. The present review concentrates on recent developments that have been built in magnetic nanostructures-based solid phase extraction, speciation and quantification of chromium ions. Besides, a description of the preparation, characterization as well as applications of various types of magnetic nanostructures, either with an inorganic or organic coating of the magnetic core, is presented.

Dextran modified magnetic nanoparticles based solid phase extraction coupled with linear sweep voltammetry for the speciation of Cr(VI) and Cr(III) in tea, coffee, and mineral water samples.

A simple and fast solid phase microextraction method using magnetic dextran (Sephadex G-150) as a sorbent was developed for the extraction, separation and speciation analysis of chromium ions. The retained Cr(VI) ions on the magnetic dextran sorbents were eluted and detected by linear sweep voltammetry at the gold nanoparticles modified screen- printed carbon electrode. The linear range, detection limit, quantification limit, and preconcentration factor of the established method for Cr(VI) and Cr(III) were calculated to be 0.

Conducting polymer modified screen-printed carbon electrode coupled with magnetic solid phase microextraction for determination of caffeine.

In the current study, we introduce magnetic solid phase microextraction coupled with electrochemical detection of caffeine. A commercially available disposable screen-printed carbon electrodes modified with poly Alizarin Red S are employed as electrochemical sensors in the detection stage. However, the suitability of magnetic solid phase microextraction for electroanalytical methods such as square wave voltammetry has not been declared.

Square-wave stripping voltammetric determination of caffeic acid on electrochemically reduced graphene oxide-Nafion composite film.

An electrochemical sensor composed of Nafion-graphene nanocomposite film for the voltammetric determination of caffeic acid (CA) was studied. A Nafion graphene oxide-modified glassy carbon electrode was fabricated by a simple drop-casting method and then graphene oxide was electrochemically reduced over the glassy carbon electrode. The electrochemical analysis method was based on the adsorption of caffeic acid on Nafion/ER-GO/GCE and then the oxidation of CA during the stripping step.