Investigation on the effect of zinc oxide nanoparticles in the aggregation of hen egg lysozyme

Protein misfolding and aggregation are responsible for several human pathologies commonly known as protein misfolding diseases. The various examples of protein misfolding diseases are: Alzheimer disease, spongiform encephalopathy, diabetes type 2, serpin-deficiency disorder, Huntington disease, Parkinson disease, amyloid polyneuropathy, and several others. The current research work was carried out to investigate the potential of ZnO nanoparticle to prevent lysozyme aggregation. ZnO nanoparticles were synthesized by chemical precipitation method from Zinc acetate dihydrate and urea. The optical, morphological and structural properties of synthesized ZnO nanoparticles have been studied using UV-Vis spectrophotometer, SEM, DLS, XRD and EDS. UV-Vis spectroscopic study shows that ZnO nanoparticles have surface plasmon resonance at 375nm. DLS analysis shows the average size of synthesized ZnO nanoparticle to be 68 nm. The EDS analysis shows the elemental composition of synthesized ZnO naoparticles and XRD study confirms the wurtzite structure of ZnO nanoparticles. The lysozyme aggregation was prepared by heating the native lysozyme at 1000C. The effect of ZnO nanoparticles on the aggregation of lysozyme was studied. DLS analysis shows the mean size of the aggregates decreases with increasing concentration of ZnO nanoparticle (NP), which was further confirmed by SEM analysis. UV-Vis and Fluorescence spectroscopic studies were performed to analyze the structural changes of lysozyme upon binding with nanoparticles. The Congo red assay was performed to study the formation of amyloid fibrils

Effects of Photocatalytic Nanoparticle Interfaces on Biological Membranes and Biomacromolecules

Inside the biological milieu, nanoparticles come in myriad shape and size those upon interaction with different biomolecules form nano-biomolecular complexes. The interface formed as a result of nanoparticle and biomolecular interactions determines fate of both the nanoparticle and biomolecules inside the biological milieu. Accordingly, investigating the interaction pattern at different interfaces will help in optimizing the use of nanoparticle for relatively wider biomedical applications. Hence, the thesis intends to study the effects of different photocatalytic nanoparticle interfaces on biological membranes, like prokaryotic and eukaryotic membranes, and biomacromolecules, like nucleic acid and protein. To this end, photocatalytic nanoparticles, such as zinc oxide (ZnONP), iron oxide (IONP) and silver (AgNP) nanoparticles, were synthesized using chemical synthesis or green synthesis methods. Initially, the effects of interfacial potential and interfacial functional groups were studied against Gram-positive and Gram-negative bacteria. The studies demonstrated that the interfacial potential and surface functionality significantly affect interaction pattern at the interface, which defines anti-bacterial/cytocompatible property of nanoparticles. In addition, second part of the thesis explored the effect of nanoparticle surface defects on cytotoxic and antimicrobial propensities of nanoparticle. The study revealed that energy band gap reduction significantly enhances the oxidative stress in cells, leading viable cells into non-viable cells. The second part, unlike the first part of the thesis where the focus was cell membrane functionality, focused on the interface effects on nucleic acid. Third objective of the thesis observed photocatalytic nanoparticle interaction with antimicrobial peptide (AMP), like nisin, and its effect on the peptide conformational and functional dynamics. The interaction leading into nisin assembly onto AgNP interface enhanced the efficacy of peptide by many folds, without significant change in peptide conformation. Whereas in fourth objective, interaction with globular protein, like lysozyme, showed that the assembly onto ZnONP interface led into conformational rearrangement that hinders the amyloidogenic propensity of lysozyme in studied conditions. Nevertheless, with increase in ZnONP fraction in the conjugate mixtures, the protein attains relatively more regular conformation than partially unfolded conformation at pH 9. Insignificant conformational changes in lysozyme assembled onto ZnONP interface was observed at pH 7.4. Thus, the findings, altogether, suggested that the physico-chemical properties of photocatalytic nanoparticle interface significantly affect the fate of biomembrane and biomacromolecules inside the biological milieu

Enhancement of properties of recycled coarse aggregate concrete using bacteria

Due to rapid construction, necessity for raw materials of concrete, especially coarse aggregate, tends to increase the danger of early exhaustion of the natural resources. An alternative source of raw materials would perhaps delay the advent of this early exhaustion. Recycled coarse aggregate (RCA) plays a great role as an alternative raw material that can replace the natural coarse aggregate (NCA) for concrete. Previous studies show that the properties of RCA concrete are inferior in quality compared to NCA concrete. This article attempts to study the improvement of properties of RCA concrete with the addition of bacteria named as Bacillus subtilis. The experimental investigation was carried out to evaluate the improvement of the compressive strength, capillary water absorption, and drying shrinkage of RCA concrete incorporating bacteria. The compressive strength of RCA concrete is found to be increased by about 20% when the cell concentration of B. subtilis is 106 cells/ml. The capillary water absorption as well as drying shrinkage of RCA are reduced when bacteria is incorporated. The improvement of RCA concrete is confirmed to be due to the calcium carbonate precipitation as observed from the microstructure studies carried out on it such as EDX, SEM, and XRD

Impact of imidazolium-based ionic liquids on the structure and stability of lysozyme

<p>Various types of water-miscible aprotic ionic liquids (ILs) with different cations (1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-octyl-3-methylimidazolium) and anions (ethylsulfate and chloride) were used as co-solvents to investigate the stability of lysozyme. Different techniques such as fluorescence, thermal absorption, and circular dichroism (CD) spectroscopy have been used for the study. Fluorescence results reveal that the addition of ILs (1-ethyl-3-methylimidazolium ethyl sulfate and 1-ethyl-3-methylimidazolium) increases the hydrophobicity around the tryptophan environment in lysozyme. CD analysis and temperature-dependent studies were done to investigate the stability of the protein. From the CD analysis, it was observed that the ILs keep the native structure of protein intact. Thermal denaturation studies depicted that the melting temperature of the protein increased in the presence of ILs (1-ethyl-3-methylimidazolium ethyl sulfate and 1-ethyl-3-methylimidazolium), which indicates the stabilization of the protein.</p