Thin Film Formation of HSA in the Presence of CTAB-Capped Gold Nanorods through Phase Separation.

Phase behavior in protein-nanoparticle systems in light of protein corona formation has been investigated. We report the formation of HSA thin films following the addition of a solid protein to a solution of CTAB-capped gold nanorods (AuNRs) via phase separation. The phase separation behavior was observed through UV-vis spectroscopy, turbidity assays, and DLS studies. UV-vis spectra for the protein-AuNR solution indicated a possible self-assembly formation by CTAB-HSA complexes and AuNR-HSA conjugates. The turbidity was found to increase linearly up to 30-50% v/v for each component. The growth phase slope is proportional to the concentration of the components, AuNRs, and HSA, with no lag phase. Dynamic light scattering (DLS) shows the formation of larger aggregates with time, implying a segregated phase of AuNR-HSA and a CTAB-HSA-AuNR network. ζ-potential values confirm surface modification, implying protein corona formation on nanorods. The thin films were also characterized using SEM, AFM, SAXS, XPS, FTIR, and TGA studies. SEM images show a smooth surface with a reduced number of pores, indicating the compactness of the deposited structure. AFM shows two different structural pattern formations with the deposition, indicating possible self-assembly of the protein-conjugated nanoparticles. FTIR studies indicate a change in the hydrogen bonding network and confirm the CTAB-HSA-AuNR complex network formation. The XPS studies indicate Au-S bond formation, along with Au-S-S-Au interactions. SAXS studies indicate the formation of aggregates (oligomers), as well as the presence of dominant attractive intermolecular interactions in the thin films.

Cell Penetrability of a γ-Crystallin Peptide Fragment from the Discarded Cataractous Eye Emulsion.

The efficiency of the intracellular transport of medication and target specificity is frequently hampered by biological obstacles. The potential for therapeutic use of peptide fragments from naturally occurring proteins is promising, as peptides exhibit high selectivity due to several possibilities of interaction with their target. Certain peptide sequences, often referred to as cell-penetrating peptides (CPPs), are those that can penetrate cell membranes. Our goal is to find these sequences in the discarded postcataractery surgery emulsion known as the cataractous eye protein isolate (CEPI). One peptide fragment from this discarded protein has been identified to be a potential CPP based on the similarities with other well-known CPPs. Cell membrane penetrability and cytotoxicity of the peptide have been investigated. Fibroblast cells were incubated with the fluorescently labeled peptide and were observed under fluorescence as well as under confocal microscopy. It was found that the peptide possesses a cell-penetrating ability.

Understanding Conformational Changes in Human Serum Albumin and Its Interactions with Gold Nanorods: Do Flexible Regions Play a Role in Corona Formation?

The importance of protein-nanoparticle (NP) conjugates for biomedical applications has seen an exponential growth in the past few years. The protein corona formation on NPs with human serum albumin (HSA), being the most abundant protein in blood serum, has become one of the most studied protein analyses under NP-protein interactions as HSA is readily adsorbed on the surface of the NPs. Understanding the fate of the NPs in physiological media along with the change in biological responses due to the formation of the protein corona thus becomes important. We analyzed the HSA protein corona formation on gold nanorods (AuNRs) through different spectroscopic studies in addition to the effects of change in the protein concentration on the protein-NP interactions. Different imaging techniques such as high-resolution transmission electron microscopy, field emission scanning electron microscopy, and atomic force microscopy were used to determine the morphology and the dimensions of the nanorods and the protein-nanorod conjugates. Fourier-transform infrared data showed a reduction in the α-helix content and an increase in ß-sheet content for the HSA-AuNR conjugate compared to the native protein. A decrease in steady-state fluorescence intensity occurred with instant addition of AuNR to HSA showing better and efficient quenching of Trp fluorescence for the lower concentration of protein. Time-correlated single photon counting results showed greater energy transfer efficiency and faster decay rate for higher concentrations of proteins. The circular dichroism study gives insight into the secondary structural changes due to unfolding, and a greater change was observed for lower concentrations of protein due to a thermodynamically stable protein corona formation. Surface-enhanced Raman spectroscopy (SERS) indicated the presence of aromatic residues such as Phe, Tyr, and Cys that appear to be close to the surface of the AuNRs in addition to hydrophobic interactions between AuNR and the protein. The disordered and flexible regions mapped onto HSA (PDB: 1AO6), predicted by the intrinsically disordered region predictors, point toward the interactions of similar residues with the nanorods observed from SERS and fluorescence studies. These studies could provide a clearer understanding of the interactions between HSA and AuNRs for possible biological applications.

Thermodynamics of the Association of Aminoglycoside Antibiotics with Human Angiogenin.

BACKGROUND: The body needs to maintain a firm balance between the inducers and inhibitors of angiogenesis, the process of proliferation of blood vessels from pre-existing ones. Human angiogenin (hAng), being a potent inducer of angiogenesis, is a cause of tumor cell proliferation, therefore its inhibition becomes a vital area of research. Aminoglycosides are linked ring systems consisting of amino sugars and an aminocyclitol ring and are in use in clinical practices for a long time. These compounds have found clinical uses as antibacterial agents that inhibit bacterial protein synthesis. OBJECTIVE: Gentamycin C1, Kanamycin A, Neomycin B, Paromomycin I, and Streptomycin A are commonly used aminoglycoside antibiotics that have been used for the present study. Among these, Neomycin has reported inhibitory activity against angiogenin-induced angiogenesis on the chicken chorioallantoic membrane. This study focuses on the thermodynamic parameters involved in the interactions of these antibiotics with hAng. METHODS: Agarose gel-based assay, Fluorescence quenching studies and Docking studies. RESULTS: Anti-ribonucleolytic effect of the antibiotics was observed qualitatively using an agarose gelbased assay, which shows that Neomycin exhibits the most efficient inhibition of hAng. Fluorescence quenching studies at different temperatures, using Stern-Volmer and van't Hoff equations provide information about the thermodynamics of binding, which furthermore highlights the higher binding constant of Neomycin. Docking studies showed that the antibiotics preferably interact with the nuclear translocation site, except Streptomycin, which shows affinity towards the ribonucleolytic site of the protein with very less affinity value. CONCLUSION: The study has shown the highly spontaneous formation of Neomycin-hAng complex, giving an exothermic reaction with increase in the degree of freedom of the protein-ligand complex.

Exploring of bacterial blight resistance in landraces and mining of resistant gene(s) using molecular markers and pathogenicity approach.

Bacterial blight, one of the oldest and most severe diseases of rice poses a major threat to global rice production and food security. Thereafter, sustainable management of this disease has given paramount importance globally. In the current study, we explored 792 landraces to evaluate their disease reaction status against three highly virulent strains (BXo69, BXo87 and BXo93) of Xanthomonas oryzae pv. oryzae (Xoo). Subsequently, we intended to identify the possible candidate resistant (R) genes responsible for the resistant reaction using six STS (Sequence Tagged Site) markers correspond to Xa4, xa5, Xa7, xa13, Xa21 and Xa23 genes and finally, we evaluated morphological variability of the potential bacterial blight resistant germplasm using quantitative traits. Based on pathogenicity test, a single germplasm was found as highly resistant while, 33 germplasm were resistant and 40 were moderately resistant. Further molecular study on these 74 germplasm divulged that 41 germplasm carried Xa4 gene, 15 carried xa5 gene, 62 carried Xa7 gene, 33 carried xa13 gene, and 19 carried Xa23 gene. Only a single germplasm found to carry Xa21 gene. Interestingly, we found a wide range of gene combinations ranged from 2 to 4 genes among the germplasm, where 10 germplasm carried 4 genes, 15 germplasm carried 3 genes and 38 germplasm carried 2 genes of various combinations. Notably, G3 genotype (Acc. No. 4216; highly resistant) having Xa4, Xa7, xa13, Xa21 and G43 genotype (Acc.No. 1523; resistant) having Xa4, xa5, xa13 and Xa23 gene combination being the most effective against all the Xoo strains. Nonetheless, UPGMA dendrogram and heatmap analysis based on quantitative traits identified two clusters viz. cluster-III and cluster-VIII with multiple desired traits. The outcome of this study would enrich and diversify the rice gene pool and would be useful for the development of durable bacterial blight resistant varieties. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01139-x.

Genomic DNA-mediated formation of a porous Cu2(OH)PO4/Co3(PO4)2·8H2O rolling pin shape bifunctional electrocatalyst for water splitting reactions.

Among the accessible techniques, the production of hydrogen by electrocatalytic water oxidation is the most established process, which comprises oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Here, we synthesized a genomic DNA-guided porous Cu2(OH)PO4/Co3(PO4)2·8H2O rolling pin shape composite structure in one pot. The nucleation and development of the porous rolling pin shape Cu2(OH)PO4/Co3(PO4)2·8H2O composite was controlled and stabilized by the DNA biomolecules. This porous rolling pin shape composite was explored towards electrocatalytic water oxidation for both OER and HER as a bi-functional catalyst. The as-prepared catalyst exhibited a very high OER and HER activity compared to its various counterparts in the absence of an external binder (such as Nafion). The synergistic effects between Cu and Co metals together with the porous structure of the composite greatly helped in enhancing the catalytic activity. These outcomes undoubtedly demonstrated the beneficial utilization of the genomic DNA-stabilised porous electrocatalyst for OER and HER, which has never been observed.

Dumbbell-Shaped Ternary Transition-Metal (Cu, Ni, Co) Phosphate Bundles: A Promising Catalyst for the Oxygen Evolution Reaction.

Development of economical and high-performance electrocatalysts for the oxygen evolution reaction (OER) is of tremendous interest for future applications as sustainable energy materials. Here, a unique member of efficient OER electrocatalysts has been developed based upon structurally versatile dumbbell-shaped ternary transition-metal (Cu, Ni, Co) phosphates with a three-dimensional (3D) (Cu2(OH)(PO4)/Ni3(PO4)2·8H2O/Co3(PO4)2·8H2O) (CNCP) structure. This structure is prepared using a simple aqueous stepwise addition of metal ion source approach. Various structural investigations demonstrate highly crystalline nature of the composite structure. Apart from the unique structural aspect, it is important that the CNCP composite structure has proved to be an excellent electrocatalyst for OER performance in comparison with its binary or constituent phosphate under alkaline and neutral conditions. Notably, the CNCP electrocatalyst displays a much lower overpotential of 224 mV at a current density of 10 mA cm-2 and a lower Tafel slope of 53 mV dec-1 with high stability in alkaline medium. In addition, X-ray photoelectron spectroscopy analysis suggested that the activity and long-term durability for the OER of the ternary 3D metal phosphate are due to the presence of electrochemically dynamic constituents such as Ni and Co and their resulting synergistic effects, which was further supported by theoretical studies. Theoretical calculations also reveal that the incredible OER execution was ascribed to the electron redistribution set off in the presence of Ni and Cu and the most favorable interaction between the *OOH intermediate and the active sites of CNCP. This work may attract the attention of researchers to construct efficient 3D ternary metal phosphate catalysts for various applications in the field of electrochemistry.

Restriction of microwave-induced amyloid fibrillar growth by gold nanoparticles.

Microwave radiations from various electronic devices are of serious health concern. In this article, using spectroscopic measurements, we show that the microwave radiation of strength 22 dBm and frequency 10 GHz facilitates protein fibrillation. However, this adverse effect of low-field radiation can be restricted by the presence of biocompatible citrate-capped gold nanoparticles. The dissipative field by metallic particles is able to disrupt the fibrillar network. We believe that the obtained results paved a way to find a therapeutic measure to combat fibrillation related diseases.

EMI shielding of ABS composites filled with different temperature-treated equal-quantity charcoals.

Acrylonitrile-butadiene-styrene (ABS) composites were prepared by dry mixing equal-quantity (20 wt%) charcoals treated at different temperatures followed by hot compression. Processing parameters were kept the same. Seven samples of the same charcoal were modified for carbonization at different temperatures varying from 500 °C to 1100 °C in steps of 100 °C. Temperature treatment of charcoal crafts an increase in the conductivity of ABS composites, primarily accountable for the enhancement of shielding. The electromagnetic shielding effectiveness in the X-band (8.2-12.4 GHz) has been discovered to significantly increase for composites with ascending temperature-treated charcoals. An abrupt increase in the conductivity of ABS composites containing equal quantities of charcoal subjected to enhanced temperature treatments truly explains the effective absorption behaviour. The composite containing 1100 °C temperature-treated charcoal shows absorption-dominated SE of ∼36.8 dB at 11.6 GHz. Dielectric behaviour proclaims a decrease in dielectric loss (ε'') with an increase in the frequency. Besides this, the increased carbonization temperatures also show increased porosity and high dielectric losses. The scanning electron microscopy studies validate the increase in the porosity of charcoals due to the increase in the treatment temperature. The results are promising for the development of custom-made shielding composites possessing equal quantities of charcoal treated at enhanced temperatures.