CeO₂-CePO₄ and Ag@CeO₂-CePO₄ nanocomposites from Penaeus semisulcatus for heavy metals sensing, UV shielding and cytotoxic applications

CeO2-CePO4 and Ag@CeO2-CePO4 nanocomposites (NCs) were prepared using Penaeus semisulcatus and characterized by various analytical techniques. The NCs exhibited spherical morphology, with average particle sizes measuring 2.36 nm, 3.30 nm and 29.64 nm for the samples air dried, annealed at 550 °C and 800 °C respectively, and the Selected Area Electron Diffraction patterns from HR-TEM revealed their crystalline nature. In 3d X-ray Photoelectron Spectra (XPS) of NCs, the highest binding energies were observed at 916.46 eV (3d3/2) and 898.16 eV (3d5/2) with spin–orbit splitting of 18.3 eV. The X-Ray Diffraction (XRD) patterns of the NCs showed peaks typical of both CeO2 and CePO4 phases. The Fourier Transform-Infra Red (FT-IR) spectrum contained bands due to Ce-O stretching at 560 cm−1 and PO43- groups at 1008 and 711 cm−1, which was further substantiated by Raman spectrum, which had an intense peak at 468 cm−1 corresponding to F2g band of CeO2 and another peak at 976 cm−1 due to PO43- tetrahedron. In the Ultraviolet-Visible Diffuse Reflectance Spectra (UV-Vis DRS), the broad absorption peak at 352 nm and minor peaks around 300 nm confirmed the formation of CeO2-CePO4 NCs. The green synthesized NCs were excellent fluorescence sensors for Pb2+, Cd2+ and Hg2+ in a wide range of concentrations, from 5.0x10-9 M to 4.0x10-5 M. The concentration Vs. emission fitting plot had three distinctive linear ranges. At a low concentration range (5x10-9 to 3.5x10-7 M), the limit of detection for Pb2+, Cd2+ and Hg2+ was found to be 2.41x10-8, 2.56x10-8 and 3.11x10-8 M. The sensitive detection of a mixture of heavy metal ions in ppb levels by biocompatible NCs gained insight in treating aqueous industrial wastes. Further, NCs showed cytotoxicity and UV shielding properties.</p

Nitrogen doped fluorescent carbon dots from Delonix regia for Fe(III) and cysteine sensing, DNA binding and bioimaging

The current work primarily deals with the synthesis of nitrogen rich carbon dots from Delonix regia along with characterisation using several analytical techniques for fluorescent sensing of Fe(III) and cysteine, electrochemical sensing of hydrogen peroxide and DNA binding. The average particle size of the spherical N-CDs is calculated to be 2.23 nm with a quantum yield of 33.5%. The SAED pattern from HR-TEM confirms the slight graphitisation of the N-CDs along with the amorphous carbon core. The synthesised N-CDs served as an efficient turn off sensor for Fe(III) with a detection limit of 5.76 × 10-7 M and turn on sensor for L-Cysteine with a detection limit of 3.76 × 10-4 M. The nature and extent of binding of the N-CDs with ctDNA was evaluated and the binding constant from the Benesi Hildebrand plot is calculated to be 6.49 (mg/mL)-1. The limit of detection was found to be 71 µM for electrochemical sensing of hydrogen peroxide. The less cytotoxic and excellent biocompatible nature of the N-CDs have been taken advantage to image L6 cells and SKMEL cells

PROTECTIVE ROLE OF BACOSIDE A ON BLOOD BRAIN BARRIER INTEGRITY

Oxidative stress induced loss of neuronal function with age is related to disruption of the blood brain barrier (BBB)integrity. The protective effect of Bacopa monnieri in combating oxidative stress induced dysfunction of BBB is being studied. We extracted, isolated and quantified bacoside A from bacopa leaf powder. An invivo trial was conducted in rats, which were treated with two doses of Bacoside A (200 and 400 mg/kg BW), through intra-peritoneal route for 7 consecutive days and the efficacy of the treatment was tested by studying the integrity of BBB using Evan’s Blue (EB) dye extravasation, antioxidant enzyme activity and Lipid peroxidation and expression of tight junction (TJ) protein occludin and ROS induced factor Nrf2in the brain. Bacoside A treatment for 7 days resulted in a dose dependent significant (p&lt;0.001) decrease in concentration of EB into the brain indicative of minimum disruption in BBB integrity compared to control rats. Similarly, bacoside A significantly (p&lt;0.001) increased the activity of antioxidant enzymes viz. SOD, catalyse and GPx, with a concomitant significant (p&lt;0.001) decrease in lipid peroxidation in brain. Further, a small dose depended increase in the relative mRNA expression of occludin and Nrf2 was observed in brain of rats treated with bacoside A. Hence, it is concluded that the beneficial effect of Bacoside A in restoring integrity of BBB could be associated with the increased expression TJ protein occludin and ROS induced transporter Nrf2 that might have strengthened the TJ and minimized ROS induced damage of the BBB.&nbsp