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3
Date Added: Jan 9, 2022
Date Added: Jan 9, 2022
Jargon-minized Summary: A room-temperature biosensor based on the quantum mechanical property of Nitrogen-Vacancy(NV) centers in diamond was used to detect the action potential(AP) signal from mice' hind limb muscles. Specifically, ion flows associated AP signal generates weak current and produces magnetic field, which were detected by the NV centers. Since the experiment was carried out in an unshielded environment, the authors further explored de-noise solutions that could remove background and obtained AP magnetic signal that correlates well with simultaneous probe electrophysiology measurement. Optimistically, the authors believe that this is a step towards non-invasive mapping of the brain neuron signal using diamond quantum sensor. Original Summary: The ability to perform noninvasive and non-contact measurements of electric signals produced by action potentials is essential in biomedicine. A key method to do this is to remotely sense signals by the magnetic field they induce. Existing methods for magnetic field sensing of mammalian tissue, used in techniques such as magnetoencephalography of the brain, require cryogenically cooled superconducting detectors. These have many disadvantages in terms of high cost, flexibility and limited portability as well as poor spatial and temporal resolution. In this work we demonstrate an alternative technique for detecting magnetic fields generated by the current from action potentials in living tissue using nitrogen vacancy centres in diamond. With 50 pT/$$\sqrt{\text {Hz}}$$sensitivity, we show the first measurements of magnetic sensing from mammalian tissue with a diamond sensor using mouse muscle optogenetically activated with blue light. We show these proof of principle measurements can be performed in an ordinary, unshielded lab environment and that the signal can be easily recovered by digital signal processing techniques. Although as yet uncompetitive with probe electrophysiology in terms of sensitivity, we demonstrate the feasibility of sensing action potentials via magnetic field in mammals using a diamond quantum sensor, as a step towards microscopic imaging of electrical activity in a biological sample using nitrogen vacancy centres in diamond.
2
Date Added: Dec 30, 2021
Date Added: Dec 30, 2021
Inclusions in a brush are entropically disfavored, as they constrain the surrounding brush chains and limit possible chain conformations. As a result, polymer brushes can be used in lubrication or as biological coatings against toxic molecules. Here, we study the interaction of nanoparticles with a brush using self-consistent field theory (SCFT). For a large particle compressing a brush, we reproduce the linear scaling of the repulsive potential with the particle radius found previously using SCFT. Also, we find that this linearity gives way to a nonlinear (parabolic or cubic) dependence on the particle size for particles inserted deeply into the brush, consistent with earlier particle-based simulations. The insertion of particles disrupts the brush, changing polymer–particle interactions for subsequent nanoparticles, thus introducing effective particle–particle interactions mediated by the brush. When the grafting point is mobile in the plane of the grafting surface, our results suggest that the brush promotes clustering of inclusions. In contrast, inclusions tend to be dispersed when the grafting point is fixed. Finally, we discuss the biological implications of these findings: interactions of antimicrobial peptides with bacterial lipopolysaccharides and clustering of integrin on cancerous cell membranes.
5
Date Added: Jul 16, 2021
Date Added: Jul 16, 2021
A most important endeavor in modern materials’ research is the current shift toward green environmental and sustainable materials. Natural resources are one of the attractive building blocks for making environmentally friendly materials. In most cases, however, the performance of nature-derived materials is inferior to the performance of carefully designed synthetic materials. This is especially true for conductive polymers, which is the topic here. Inspired by the natural role of proteins in mediating protons, their utilization in the creation of a free-standing transparent polymer with a highly elastic nature and proton conductivity comparable to that of synthetic polymers, is demonstrated. Importantly, the polymerization process relies on natural protein crosslinkers and is spontaneous and energy-efficient. The protein used, bovine serum albumin, is one of the most affordable proteins, resulting in the ability to create large-scale materials at a low cost. Due to the inherent biodegradability and biocompatibility of the elastomer, it is promising for biomedical applications. Here, its immediate utilization as a solid-state interface for sensing of electrophysiological signals, is shown.
5
Date Added: Mar 9, 2021
Date Added: Mar 9, 2021
Photodynamic treatment is a promising tool for the therapy of multidrug-resistant bacteria. In this study, we highlight photosensitizer-loaded hydrogels as an application system for infected wounds. The poly(ethylene glycol) diacrylate-based and electron beam-polymerized hydrogels were mechanically stable and transparent. They were loaded with two photoactive, porphyrin-based drugs – tetrakis(1 methylpyridinium-4-yl)porphyrin p-toluenesulfonate (TMPyP) and tetrahydroporphyrin – p toluenesulfonate (THPTS). The hydrogels released a sufficient amount of the photosensitizers (up to 300 μmol l−1), relevant for efficiency. The antimicrobial effectivity of loaded hydrogels was investigated in a tissue-like system as well as in a liquid system against a multiresistant Escherichia coli. In both systems, light induced eradication was possible. In contrast, hydrogels alone showed only minor antimicrobial activity. Furthermore, the loaded hydrogels were successfully tested against seven multidrug-resistant bacterial strains, namely Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Achromobacter xylosoxidans. The eradication of these pathogens, except A. xylosoxidans, was successfully demonstrated. In general, TMPyP-loaded hydrogels were more effective than THPTS-loaded ones. Nevertheless, both photosensitizers displayed effectivity against all investigated bacteria strains. Taken together, our data demonstrate that photosensitizer-loaded hydrogels are a promising new tool to improve the treatment of wounds infected with problematic bacterial pathogens.
7
Date Added: Dec 13, 2020
Date Added: Dec 13, 2020
Simulating huge biomolecular complexes of million atoms at relevant biological timescales is becoming accessible to the broad scientific community. That proves to be crucial for urgent responses against emergent diseases in real time. Yet, there are still some issues to be overcome regarding the system setup so that Molecular Dynamics (MD) simulations can be run in a simple and standard way. Here, we introduce an optimized pipeline for building and simulating enveloped virus-like particles (VLP). First, the membrane packing problem is tackled with new features and optimized options in PACKMOL. This allows to prepare accurate membrane models of thousands of lipids in the context of a VLP within a few hours using a single CPU. Then the assembly of the VLP system is done within the multiscale framework of the coarse-grained SIRAH force field. Finally, the equilibration protocol provides a system ready for production MD simulations within a few days on broadly accessible GPU resources. The pipeline is applied to study the Zika Virus as a test case for large biomolecular systems. The multiscale scheme is well preserved along the simulation as evidenced from the radial distribution function of each constituent. The VLP stabilizes at approximately 0.5 ms of MD simulation, reproducing correlations greater than 0.90 against experimental density maps from cryo-electron microscopy. Detailed structural analysis of the protein envelope also shows very good agreement in root mean square deviations and B-factors with the experimental data. A rationale for a possible role of anionic phospholipids in stabilizing the envelope is introduced. The presented pipeline can be extrapolated to study other viral systems as well as intracellular compartments, paving the way to whole cell simulations.