Sol-gel synthesized nickel oxide (NiO) film deposited onto indium tin oxide (ITO) coated glass plate has been utilized for the development of sensitive and stable DNA biosensor and demonstrated for diagnosis of Visceral Leishmaniasis also known as Kala-azar. Leishmania specific sensor is developed by immobilizing 23mer DNA sequence (oligonucleotide) identified from 18S rRNA gene sequences from Leishmania donovani. Characterization studies like X-ray diffraction and Scanning Electron Microscopy revealed the formation of nano-structured NiO, while immobilization of single strand (ss)-DNA of Leishmania was supported by UV-visible, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy techniques. Response studies of ss-DNA/NiO/ITO bioelectrode are carried out using differential pulsed voltammetry in presence of methylene blue redox dye as a redox mediator. A linear response is obtained in the wide concentration range of 2pg/ml to 2μg/ml of complementary target genomic DNA (parasite DNA) within the variation of 10% for 5 sets of studies. The observed results holds promise for not only diagnosis of Kala-azar patients but also enormous potential of the nano NiO based probe for development of stable and sensitive biosensors.
Delafossite CuMnO 2 powder composed of earth-abundant elements was synthesized by a sol-gel process and thoroughly characterized by powder X-ray diffraction, SEM, XPS, FT-IR, and Raman spectroscopy. More importantly, their electrocatalytic performances for oxygen and hydrogen evolution reactions (OER and HER) have been fully investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and linear sweep voltammetry with a rotating electrode in 1 M KOH electrolyte versus Ag/AgCl. Based on the measurements from these CuMnO 2 -based working electrodes, the specific capacitance, total charge, most accessible charge, electrochemically active surface area, and roughness factor were calculated for the first time. Their stability was also studied for cost-effective and active electrode material. Furthermore, by comparing measurements at 1600 rpm and no rotation of the electrodes in alkaline media, the delafossite CuMnO 2 synthesized in this work showed current densities of 12.3 mA/cm 2 at 1600 rpm and 11.9 mA/cm 2 at no rotation for OER and 6.9 mA/cm 2 and 6.3 mA/cm 2 for HER. Overall, our study demonstrated that delafossite CuMnO 2 possesses effective bifunctional OER and HER activities.
Persistent luminescent nanocrystals (PLNCs) in the sub‐10 nm domain are considered to be the most fascinating inventions in lighting technology owing to their excellent performance in anti‐counterfeiting, luminous paints, bioimaging, security applications, etc. Further improvement of persistent luminescence (PersL) intensity and lifetime is needed to achieve the desired success of PLNCs while keeping the uniform sub‐10 nm size. In this work, the concept of molten salt confinement to thermally anneal as‐synthesized ZnGa2O4:Cr3+ (ZGOC) colloidal NCs (CNCs) in a molten salt medium at 650 °C is introduced. This method led to significantly monodispersed and few agglomerated NCs with a much improved photoluminescence (PL) and PersL intensity without much growth in the size of the pristine CNCs. Other strategies such as i) thermal annealing, ii) overcoating, and iii) the core–shell strategy have also been tried to improve PL and PersL but did not improve them simultaneously. Moreover, directly annealing the CNCs in air without the assistance of molten salt could significantly improve both PL and PersL but led to particle heterogeneity and aggregation, which are highly unsuitable for in vivo imaging. We believe this work provides a novel strategy to design PLNCs with high PL intensity and long PersL duration without losing their nanostructural characteristics, water dispersibility and biocompatibility.
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