Heterogeneous and Cooperative Rupture of Histidine-Ni2+ Metal-Coordination Bonds on Rationally Designed Protein Templates.

Metal-coordination bonds, a highly tunable class of dynamic noncovalent interactions, are pivotal to the function of a variety of protein-based natural materials and have emerged as binding motifs to produce strong, tough, and self-healing bioinspired materials. While natural proteins use clusters of metal-coordination bonds, synthetic materials frequently employ individual bonds, resulting in mechanically weak materials. To overcome this current limitation, we rationally designed a series of elastin-like polypeptide templates with the capability of forming an increasing number of intermolecular histidine-Ni2+ metal-coordination bonds. Using single-molecule force spectroscopy and steered molecular dynamics simulations, we show that templates with three histidine residues exhibit heterogeneous rupture pathways, including the simultaneous rupture of at least two bonds with more-than-additive rupture forces. The methodology and insights developed improve our understanding of the molecular interactions that stabilize metal-coordinated proteins and provide a general route for the design of new strong, metal-coordinated materials with a broad spectrum of dissipative time scales.

Pulling the Brakes on Fast and Furious Multiple Drug-Resistant (MDR) Bacteria.

Life-threatening bacterial infections have been managed by antibiotics for years and have significantly improved the wellbeing and lifetime of humans. However, bacteria have always been one step ahead by inactivating the antimicrobial agent chemically or by producing certain enzymes. The alarming universal occurrence of multidrug-resistant (MDR) bacteria has compelled researchers to find alternative treatments for MDR infections. This is a menace where conventional chemotherapies are no longer promising, but several novel approaches could help. Our current review article discusses the novel approaches that can combat MDR bacteria: starting off with potential nanoparticles (NPs) that efficiently interact with microorganisms causing fatal changes in the morphology and structure of these cells; nanophotothermal therapy using inorganic NPs like AuNPs to destroy pathogenic bacterial cells; bacteriophage therapy against which bacteria develop less resistance; combination drugs that act on dissimilar targets in distinctive pathways; probiotics therapy by the secretion of antibacterial chemicals; blockage of quorum sensing signals stopping bacterial colonization, and vaccination against resistant bacterial strains along with virulence factors. All these techniques show us a promising future in the fight against MDR bacteria, which remains the greatest challenge in public health care.

Investigative evaluation of Cassia absus for antibacterial capacity and biomimetic synthesis of silver nanoparticles.

Cassia absus is used for medicinal purposes for a long time all over the world. In this study, the authors report the antimicrobial potential of C. absus extracts obtained with different solvents. The extract(s) obtained with ethyl acetate yielded the best antibacterial effects because of a rich supply of oxalates and alkaloids in it. The same extract was also exploited for reducing Ag+ ions (to metallic Ag0) for the synthesis of nanoparticles. Electron microscopy revealed that the silver nanoparticles were ∼18-25 nm in diameter. The Fourier-transform infrared evaluation pointed towards the fact that flavonoids present in the plant extract were acting as reductants while amino groups were the bound stabilisation agents to the synthesised nanoparticles limiting the diameter to a certain threshold and avoiding aggregation naturally. A comparative antibacterial assay of C. absus versus Ag nanoparticles showed that the nanoparticles as well as organic (ethyl acetate) extract of the plant checked the growth of selected (MDR) superbugs. However, the biosynthesised Ag nanoparticles returned better antibacterial efficacies than ethyl acetate extract.

Respiring cellular nano-magnets.

Magnetotactic bacteria provide an interesting example for the biosynthesis of magnetic (Fe3O4 or Fe3S4) nanoparticles, synthesized through a process known as biologically controlled mineralization, resulting in complex monodispersed, and nanostructures with unique magnetic properties. In this work, we report a novel aerobic bacterial strain isolated from sludge of an oil refinery. Microscopic and staining analysis revealed that it was a gram positive rod with the capability to thrive in a medium (9K) supplemented, with Fe2+ ions at an acidic pH (~3.2). The magnetic behaviour of these cells was tested by their alignment towards a permanent magnet, and later on confirmed by magnetometry analysis. The X-ray diffraction studies proved the cellular biosynthesis of magnetite nanoparticles inside the bacteria. This novel, bio-nano-magnet, could pave the way for green synthesis of magnetic nanoparticles to be used in industrial and medical applications such as MRI, magnetic hyperthermia and ferrofluids.

The Nano-Magnetic Dancing of Bacteria Hand-in-Hand with Oxygen

ABSTRACT Magnetotactic bacteria are mostly microaerophilic found at the interface between oxic-anoxic zones. We report a magnetotactic bacterial strain isolated from an oil refinery sludge sample that grows aerobically in simple chemical growth medium, 9K. They open a new window of isolation of magnetic nanoparticles through an easy natural living system.

Empty nano and micro-structured lipid carriers of virgin coconut oil for skin moisturisation.

Virgin coconut oil (VCO) is the finest grade of coconut oil, rich in phenolic content, antioxidant activity and contains medium chain triglycerides (MCTs). In this work formulation, characterisation and penetration of VCO-solid lipid particles (VCO-SLP) have been studied. VCO-SLP were prepared using ultrasonication of molten stearic acid and VCO in an aqueous solution. The electron microscopy imaging revealed that VCO-SLP were solid and spherical in shape. Ultrasonication was performed at several power intensities which resulted in particle sizes of VCO-SLP ranged from 0.608 ± 0.002 µm to 44.265 ± 1.870 µm. The particle size was directly proportional to the applied power intensity of ultrasonication. The zeta potential values of the particles were from -43.2 ± 0.28 mV to -47.5 ± 0.42 mV showing good stability. The cumulative permeation for the smallest sized VCO-SLP (0.608 µm) was 3.83 ± 0.01 µg/cm(2) whereas for larger carriers it was reduced (3.59 ± 0.02 µg/cm(2)). It is concluded that SLP have the potential to be exploited as a micro/nano scale cosmeceutical carrying vehicle for improved dermal delivery of VCO.

Green Tropical Phytoextracts - Promising Anticancer Alternative

ABSTRACT The anticancer potential of aqueous extracts of tropical plants Ficus deltoidea and Labisia pumila were tested on human prostate carcinoma (DU145) cells. The effects of these extracts on the cells were observed through several tests such as cytotoxicity MTT assay, trypan blue exclusion assay (for cell viability), fluorescence and morphological observations. Both of the plant extracts had a growth repression effect on the cells with different concentrations. The best concentration (1x10-3 μg/mL) was chosen by determining their cytotoxic effects on human prostate cancer as well as fibroblast (normal) cells. The F. deltoidea extract showed more potency and killed the cells faster than L. pumila. Morphologically both extracts affected the cells in a similar way, i.e. the cells became irregular shaped, detached themselves and kept floating in the medium.