A comparative study on intrinsic fluorescence of BSA and lysozyme proteins in presence of different divalent ions from their solution and thin film conformations.

Optical emission behaviours of lysozyme and bovine serum albumin, from bulk and thin film geometry, were studied in the presence of three different divalent ions (Mg2+ , Ca2+ or Ba2+ ) using different spectroscopic [steady-state fluorescence, UV-Vis and Fourier transform infra-red (FTIR)] techniques. Additionally, protein thin films on silicon surfaces were prepared and morphological studies were carried out using atomic force microscopy. Dynamic quenching was mainly identified for both proteins in the presence of Mg2+ , Ca2+ and Ba2+ ions. The molecular conformation of the proteins was modified in thin films compared with that in solution, consequently quenching efficiencies also varied. ATR-FTIR studies confirmed the conformational changes of proteins in the presence of all divalent ions. All metal ions used were divalent in nature and belonged to the same group of the periodic table but, depending on their individual characteristics such as electron affinity, ionic radius, etc., the magnitude of the protein and hydrated ion interaction varied and accordingly the quenching efficiency was modified. Quenching was maximum for Ca2+ ions, followed by the other two ions. Our study clearly illustrates the geometry-dependent physical and biological functions of proteins.

Functionalization of ß-lactam antibiotic on lysozyme capped gold nanoclusters retrogress MRSA and its persisters following awakening.

In this study we have reported an efficient antibacterial hybrid fabricated through surface functionalization of lysozyme capped gold nanoclusters (AUNC-L) with ß-lactam antibiotic ampicillin (AUNC-L-Amp). The prepared hybrid not only reverted the MRSA resistance towards ampicillin but also demonstrated enhanced antibacterial activity against non-resistant bacterial strains. Most importantly, upon awakening through cis-2-decenoic acid (cis-DA) exposure, the MRSA persister got inhibited by the AUNC-L-Amp treatment. Intraperitoneal administration of this hybrid eliminates the systemic MRSA infection in a murine animal model. Topical application of this nano conjugate eradicated MRSA infection from difficult to treat diabetic wound of rat and accelerated the healing process. Due to inherent bio-safe nature of gold, AUNC-L alone or in the construct (AUNC-L-Amp) demonstrated excellent biocompatibility and did not indicate any deleterious effects in in vivo settings. We postulate that AUNC-L-Amp overcomes the elevated levels of ß-lactamase at the site of MRSA antibiotic interaction with subsequent multivalent binding to the bacterial surface and enhanced permeation. Coordinated action of AUNC-L-Amp components precludes MRSA to attain resistance against the hybrid. We proposed that the inhibitory effect of AUNC-L-Amp against MRSA and its persister form is due to increased Amp concentration at the site of action, multivalent presentation and enhanced permeation of Amp through lysozyme-mediated cell wall lysis.

Glycogen-gold nanohybrid escalates the potency of silymarin.

In this study, a glycogen-gold nanohybrid was fabricated to enhance the potency of a promising hepatoprotective agent silymarin (Sly) by improving its solubility and gut permeation. By utilizing a facile green chemistry approach, biogenic gold nanoparticles were synthesized from Annona reticulata leaf phytoconstituents in combination with Sly (SGNPs). Further, the SGNPs were aggregated in glycogen biopolymer to yield the therapeutic nanohybrids (GSGNPs). Transmission electron microscopy, UV-Vis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analysis confirmed the successful formation and conjugation of both SGNPs and GSGNPs. The fabricated nanohybrids showed significant protection against CCl4-induced hepatic injury in Wistar rats and maintained natural antioxidant (superoxide dismutase and catalase) levels. Animals treated with GSGNPs (10 mg/kg) and SGNPs (20 mg/kg) retained usual hepatic functions with routine levels of hepatobiliary enzymes (aspartate transferase, alanine transaminase, alkaline phosphatase, and lactate dehydrogenase) and inflammatory markers (interleukin-1ß and tumor necrosis factor-α) with minimal lipid peroxidation, whereas those treated with 100 mg/kg of Sly showed the similar effect. These results were also supported by histopathology of the livers where pronounced hepatoprotection with normal hepatic physiology and negligible inflammatory infiltrate were observed. Significant higher plasma Cmax supported the enhanced bioavailability of Sly upon GSGNPs treatment compared to SGNPs and free Sly. Graphite furnace atomic absorption spectrophotometry analysis also substantiated the efficient delivery of GSGNPs over SGNPs. The fabricated therapeutic nanohybrids were also found to be biocompatible toward human erythrocytes and L929 mouse fibroblast cells. Overall, due to increased solubility, bioavailability and profuse gut absorption; GSGNPs demonstrated tenfold enhanced potency compared to free Sly.

Fluorescence behavior of globular proteins from their bulk and thin film conformations in presence of mono-, di- and tri-valent ions.

Photoluminescence behavior of globular proteins, lysozyme and bovine serum albumin (BSA), from their bulk and thin film conformations have been studied in presence of mono-, di- and tri-valent ions by using fluorescence and UV-Vis spectroscopy at two different temperatures and the morphology of the protein thin films have been studied by using atomic force microscopy. Protein- and ion-dependent dynamic and static quenching behaviors have been identified. While dynamic quenching is observed for lysozyme for all the three different valent ions, BSA shows no quenching for mono-valent (Na(+)) ions, dynamic quenching for di-valent (Ni(2+)) ions and static quenching for tri-valent (Fe(3+)) ions at pH≈5.5. After heat treatment, as the conformation of the protein molecules changes, the quenching efficiency for lysozyme in presence of ions decreases but shows enhancement for BSA. In thin film geometry, the molecular conformation of both lysozyme and BSA modifies on the solid surfaces and hence quenching efficiency also modifies in comparison with that of bulk and as a result the quenching efficiency for lysozyme increases but decreases for the BSA film.