Cyclodextrin-mediated gold nanoparticles as multisensing probe for the selective detection of hydroxychloroquine drug.

ß-Cyclodextrin (ß-CD) modified gold nanoparticles (AuNP) were rapidly synthesized using microwave assisted procedure. Parameters, such as time, pH and concentrations of ß-CD and gold, were optimized for the synthesis of ß-CD-AuNP. The addition of enantiomers and racemic mixture of hydroxychloroquine (R-HCQ, S-HCQ and RS-HCQ) drugs and their interaction with ß-CD led to a red shift in the surface plasmon resonance of ß-CD-AuNP. The changes associated with the introduction of HCQ in ß-CD-AuNP were studied using various characterization techniques such as UV-vis, FT-IR, XRD, dynamic light scattering, zeta potential, transmission electron microscopy, fluorescence spectroscopy and electrochemical techniques. The host-guest interaction of ß-cyclodextrin with S-HCQ, R-HCQ and RS-HCQ resulted in the aggregation of gold nanoparticles. The surface plasmon resonance at 521 nm for ß-CD-AuNP was shifted to 600, 620 and 670 nm on the addition of S-HCQ, R-HCQ and RS-HCQ, respectively, with a color change from pink to blue. The selectivity and sensitivity of the developed system for RS-HCQ were investigated and the limit of detection (LOD=3 s/m) was found to be 2.61, 0.15, and 0.85 nM for optical, fluorescence and electrochemical methods, respectively. The successful monitoring of RS-HCQ drug in pharmaceutical samples is possible with these techniques. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s11814-020-0719-7 and is accessible for authorized users.

Fast and efficient degradation of water pollutant dyes and fungicide by novel sulfur-doped graphene oxide-modified Ag3PO4 nanocomposite.

The sulfur-doped graphene oxide (sGO)-integrated Ag3PO4 composite displayed very high catalytic activity toward prominent water pollutants like textile dyes and fungicide under sunlight. The optimum amount of sGO doping was found as 5% for degradation. The novel composite degraded 99% of methylene blue (MB) in only 5 min of sunlight exposure, which is 16 and 8 times faster than Ag3PO4 and 5% GO-Ag3PO4. High mineralization was observed for MB with a total organic carbon (TOC) removal of 98% in 30 min. The composite mineralized rhodamine B, methyl orange, and acid red 18 dyes with a TOC removal above 95%. Moreover, a toxic dithiocarbamate fungicide thiram was degraded in 1 h with a TOC removal of 82% leaving less toxic thiourea. The formation of sGO-Ag3PO4 n-n heterojunction increases charge transport and photocatalytic activity of the composite to incredible extent along with hollow morphology and in situ formed Ag nanoparticles (AgNPs).

Metal oxide nanoparticles in electrochemical sensing and biosensing: a review.

This review (with (318) refs) describes progress made in the design and synthesis of morphologically different metal oxide nanoparticles made from iron, manganese, titanium, copper, zinc, zirconium, cobalt, nickel, tungsten, silver, and vanadium. It also covers respective composites and their function and application in the field of electrochemical and photoelectrochemical sensing of chemical and biochemical species. The proper incorporation of chemical functionalities into these nanomaterials warrants effective detection of target molecules including DNA hybridization and sensing of DNA or the formation of antigen/antibody complexes. Significant data are summarized in tables. The review concludes with a discussion or current challenge and future perspectives. Graphical abstract ᅟ.