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Gum arabic stabilized silver nanoparticles have been used to modify carbon paste electrodes (AgNPs-GA/CPE) for the electrochemical sensing of morin, a flavanoid. The synthesized nanoparticles, before and after modification of electrodes were characterized by UV–visible spectroscopy, X-ray diffraction (XRD), fourier transformation infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements, and thermogravimetric analysis (TGA). The uniform-sized spherical silver nanoparticles have particle sizes less than 10 nm. AgNPs-GA/CPE electrode has shown excellent electrocatalytic activity towards the oxidation of morin at a potential of 0.14 V. The factors influencing the electrochemical determination of morin such as the effect of pH, the effect of scan rate, and the effect of concentration were studied in detail. The linear dynamic range was found to be 0.65 nM to 7.0 nM with a detection limit of 0.216 nM. The developed sensor has been successfully applied for the determination of morin in mulberry leaves and almonds.

This review article portrays the progress in developing novel electrochemical sensors using morphologically varied transition metal oxides. The role and applications of transition metal oxide nanoparticles of iron, titanium, manganese, zirconium, cobalt, nickel and their composites in the field of electrochemical and bio sensing are conferred in detail. Appropriate chemical functionalization of these nanomaterials guarantees the selective and sensitive determination of target molecules including DNA or creating antigen/antibody complexes. Substantial data is summed up in the tables. This review article highlights the significance of transition metal oxide nanoparticles as promising electrode modifiers for fabrication of sensors. The review ends up with a relevant discussion, existing challenges and future scopes.

The biosynthesis of silver nanoparticles is considered to be a feasible, green, and eco-friendly method. Silver nanoparticles (AgNPs) were synthesized using badminton ball tree (Parkia biglandulosa) leaf extract and their significant physiochemical properties were characterized. The aqueous extract of the leaf of P. biglandulosa act as a reducing as well as capping agent for the reduction of Ag+ ​ions. FTIR analysis was conducted to find out the compounds that were liable for the bio-reduction of silver ions and to study the functional groups present in P. bigalandulosa leaf extract. The biologically reduced silver nanoparticles showed a surface plasmon resonance at 439 ​nm as studied from the UV–visible absorption spectrum. TEM studies confirmed the shape of the nanoparticles to be spherical with an average diameter of 15 ​nm. The anti-bacterial properties of the prepared nanoparticles were tested against Bacillus cereus by well plate method. Biosynthesized silver nanoparticles (PbAgNPs) at 0.02 ​M concentration showed the most antibacterial activity with a zone of inhibition of 7 ​mm. The high biocompatibility of the PbAgNPs by using human skin fibroblast cell line was evaluated by Alamar Blue reduction assay. The PbAgNPs had shown the highest cell viability when compared to native nanoparticles, meanwhile, a significant increase in cell viability was noted for the nanoparticles. The biosynthetic approach for synthesis was found to be a facile, rapid, single-step, safe, and effective alternative to the conventional physical/chemical methods.

Vitamin B 12 is very important for human metabolism and its deficiency can cause anemia and the production of large red blood cells. An increased concentration of methylmalonic acid (MMA) is detected much before the transformation of blood cells, which thereby is an early indicator for mild or serious Vitamin B 12 deficiency. A simple electrochemical sensor based on Palladium-Gold (PdAu) was developed by electrodeposition of PdAu nanoparticles on Polypyrrole (PPy) modified carbon fiber paper (CFP) electrode. The modified electrodes were characterized by High resolution transmission electron microscopy (HRTEM), Field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electroanalytical techniques. Differential Pulse Voltammetric (DPV) studies have established that under optimum conditions, the developed sensor exhibits a broad linear dynamic range (4.01 pM - 52.5 nM) with a very low detection limit (1.32 pM). The proposed method was effectively applied in the non-enzymatic determination of MMA at an ultralow level in human blood serum and urine samples. The method displayed high selectivity toward MMA in the presence of other interfering substances., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Nanoparticle mediated extracellular matrix may offer new and improved biomaterial to wound healing and tissue engineering applications. However, influence of nanoparticle size in extracellular matrix is still unclear. In this work, we synthesized different size of silver nanoparticles (AgNPs) comprising of 10nm, 35nm and 55nm using nutraceuticals (pectin) as reducing as well as stabilization agents through microwave irradiation method. Synthesized Ag-pectin nanoparticles were assimilated in the self-assemble process of collagen leading to fabricated collagen-Ag-pectin nanoparticle based scaffolds. Physico-chemical properties and biocompatibility of scaffolds were analyzed through FT-IR, SEM, DSC, mechanical strength analyzer, antibacterial activity and MTT assay. Our results suggested that 10nm sized Ag-pectin nanoparticles significantly increased the denaturation temperature (57.83°C) and mechanical strength (0.045MPa) in comparison with native collagen (50.29°C and 0.011MPa). The in vitro biocompatibility assay reveals that, collagen-Ag-pectin nanoparticle based scaffold provided higher antibacterial activity against to Gram positive and Gram negative as well as enhanced cell viability toward keratinocytes. This work opens up a possibility of employing the pectin caged silver nanoparticles to develop collagen-based nanoconstructs for biomedical applications., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Iron oxide nanoparticles are being viewed with interest owing to the great potential they have in the biomedical applications like MRI contrast enhancement, targeted drug delivery, hyperthermia and recently in magnetic separation of cancer cells from the body. Templated synthesis has been considered ideal for synthesis of iron oxide nanoparticles as particles are attracted magnetically, in addition to usual flocculation through van der Waals attraction. Biological templates are attractive owing to their biocompatibility and the attractive porosity and surface chemistry that nature provides. Polysaccharides like chitosan and alginate have been employed in the synthesis of a polyion complex, which provided the active-binding sites for iron(II) ions in solution to bind. The natural organization of chitosan and alginate into a porous film has been exploited to synthesize spherical iron oxide nanoparticles through careful calcination of the iron(II) conjugate film. Our experiments indicate that the formed nanoparticles are highly crystalline, confirm to the hematite structure and have a superparamagnetic response with a low coercivity of 116Oe. Particles thus synthesized were highly monodisperse with hydrodynamic diameter of 1.8 nm. The symmetric porosity of the film translates into the synthesis of well-aligned nanoparticles of iron oxide. Compared to synthesis in solution, the film-assisted synthesis offered a greater degree of control over the particle size distribution pattern, with the chitosan-alginate template providing the needed spatial separation to prevent the aggregation due to magnetostatic coupling. Such hematite nanoparticles can either be used directly or converted to paramagnetic magnetite by reduction. Zeta potential measurements indicate highly stable nanoparticles, which can therefore be conjugated to cationic liposomes carrying drugs and magnetically guided to target sites.