Metal nanoclusters (NCs) with unique chemical and physical properties have been extensively demonstrated to be emerging nanoantibiotics for fighting bacterial infections. Understanding the antibacterial mechanisms of metal nanoclusters is important for evaluating their clinical applications as nanoantibiotics. To understand the antibacterial mechanism, gold nanoclusters (AuNCs) were applied as an antibacterial agent for real-time observations of their interactions with bacteria by in situ transmission electron microscopy (TEM). In this work, a surface ligand of glutathione-conjugated (GSH)-AuNCs was prepared via a simple hydrothermal method. Optical and structural characterizations validated the successful preparation of GSH-AuNCs. Bacterial growth curves of Acetobacter aceti revealed that the antibacterial activity of GSH-AuNCs increased with the weight concentration. The antibacterial activity of GSH-AuNCs was confirmed by the intracellular reactive oxygen species (ROS) generation induced by GSH-AuNCs in A. aceti. Furthermore, real-time observations of interactions between GSH-AuNCs and A. aceti were made using in situ liquid cell TEM. Based on the results of real-time observations, GSH-AuNCs first attached onto the bacterial membranes of A. aceti by physical adsorption and then penetrated into A. aceti by internalization. Eventually, the production of intracellular ROS induced by GSH-AuNCs caused destruction of the bacterial membranes, which led to the death of A. aceti. After the bacterial membranes had been destroyed, A. aceti eventually died.

SynopsisWe report that aliphatic primary and secondary amines completely solubilize crosslinked silicone resins and rubber compositions at room temperature. The solubilization is attributed to nucleophilic cleavage of Si-0 bonds by amines, which apparently occurs selectively at crosslinking sites. The selectivity may reflect the presence of three oxygen atoma at such sites, which are expected to enhance the electrophilicity of silicon. On evaporation of amine, crosslinks are apparently regenerated as evidenced by solubility characteristics as well as f i l m properties of the reclaimed silicones. In addition to their theoretical interest, these results are potentially important from the standpoint of commercial applications as well, including the possible reclaiming of silicone-constituted furniture molds and the coating of heat-sensitive materials.During the course of studies on the application of solubility parameter methods for swelling cured we have found that aliphatic primary and secondary amines completely solubilize crosslinked siloxane polymers at room temperature. A major objective of this research was the development of solvent-based methods for facilitating the recovery of spores from plastic and rubbery materials utilized in spacecraft components. This goal was conveniently accomplished in high yields in the case of representative silicones by treatment with amines followed by plate counting methods (these results will be submitted elsewhere). Nevertheless, the unexpected finding of complete solubilization of cured silicones by amines prompted further studies on the nature of this interaction. The results are reported herein which indicate that amines react selectively at Si-0 crosslinking sites by nucleophilic substitution, as illustrated in eq. (1). Furthermore, the reversibility of this reaction is evidenced by the reformation of crosslinked sites on evaporation of amine. In addition to their theoretical interest, these results are potentially important from a technological standpoint as well, including the possible applications of reclaiming silicone-constituted furniture molds and coating of heat-sensitive materials.Initial studies were conducted with Dow Corning DC 840 silicone resin, which possesses a phenyl methyl polysiloxane backbone. The prepolymer also contains silanol (Si-OH) sites which are converted into Si-0-Si crosslinkages during curing. After curing at 24OOC for 1 hr, 50-mg samples (as cubes approximately 3 mm on a side) were suspended in 2 ml m i n e solvent

Global warming and climate change are among the most immediate challenges confronting humans in the 21st century. Artificial photosynthesis represents a promising approach to mitigating the environmental crisis. Recently, people demonstrated that interfacing semiconductor, polymer, or metal-based nanomaterials with specific bacteria can generate built-in artificial photosynthetic systems, enabling solar-to-fuel conversion by forming a basic photosynthetic unit from a network of light-harvesting receptors, molecular water splitting and CO2, or proton reduction machinery. As a cutting-edge research direction, several strategies have been employed to create the artificial photosynthetic biohybrids. Notably, understanding of the molecular basis of these photosynthetic biohybrid systems is the key to improving the solar-to-chemical conversion efficiency. In the current review, we highlight the study of charge uptake channels in biohybrid artificial photosynthetic systems using various nanomaterials and microbes. We emphasize the importance of fully understanding the structures and operating mechanisms of these hybrid systems, as well as the criterion to select suitable microbes and photosensitized nanomaterials.

Biosensors based on liquid crystal (LC) materials can be made by employing the sensitive interfacial effect between LC molecules and alignment layers on substrates. In the past, the optical texture observation method was used in the LC biosensor field. However, the method is limited by a complicated fabrication process and quantitative reproducibility of results that bv evidence that both the reliability and accuracy of LC biosensors need to be improved. In this report, we demonstrate that cholesteric LC (CLC) cells in which one substrate is coated with a vertically aligned layer can be used as a new sensing technology. The chirality of the single vertically anchored (SVA)/CLC biosensor was tested by detecting bovine serum albumin (BSA), a protein standard commonly used in the lab. The colors and corresponding spectrum of the SVA/CLC biosensor changed with the BSA concentrations. A detection limit of 1 ng/ml was observed for the SVA/CLC biosensor. The linear optical properties of the SVA/CLC biosensor produced cheap, inexpensive, and color-indicating detection of biomolecules, and may promote the technology of point-of-care devices for disease-related biomarker detection.

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Emerging life threatening pathogens such as severe acute aspiratory syndrome-coronavirus (SARS-CoV), avian-origin influenzas H7N9, and the Middle East respiratory syndrome coronavirus (MERS-CoV) have caused a high case-fatality rate and psychological effects on society and the economy. Therefore, a simple, rapid, and safe method to investigate a therapeutic approach against these pathogens is required. In this study, a simple, quick, and safe cell adhesion inhibition assay was developed to determine the potential cellular binding site on the SARS-CoV spike protein. Various synthetic peptides covering the potential binding site helped to minimize further the binding motif to 10-25 residues. Following analyses, 2 peptides spanning the 436-445 and 437-461 amino acids of the spike protein were identified as peptide inhibitor or peptide vaccine candidates against SARS-CoV.

Photobiomodulation (PBM) has recently emerged in cellular therapy as a potent alternative in promoting cell proliferation, migration, and differentiation during tissue regeneration. Herein, a single-cell near-infrared (NIR) laser irradiation system (830 nm) and the image-based approaches were proposed for the investigation of the modulatory effects in mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS), and vesicle transport in single living human adipose mesenchymal stem cells (hADSCs). The irradiated-hADSCs were then stained with 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA) and Rhodamine 123 (Rh123) to represent the ΔΨm and ROS production, respectively, with irradiation in the range of 2.5–10 (J/cm2), where time series of bright-field images were obtained to determine the vesicle transport phenomena. Present results showed that a fluence of 5 J/cm2 of PBM significantly enhanced the ΔΨm, ROS, and vesicle transport phenomena compared to the control group (0 J/cm2) after 30 min PBM treatment. These findings demonstrate the efficacy and use of PBM in regulating ΔΨm, ROS, and vesicle transport, which have potential in cell proliferation, migration, and differentiation in cell-based therapy.