The effects of mild oxidation (burning) of two synthetic graphites on the reversible false(QRfalse) and irreversible false(QIRfalse) capacities, anode‐degradation rate (on cycling) in three different electrolytes and graphite‐surface topology have been studied. STM images of both modified graphites show nanochannels having an opening of a few nanometers and up to tens of nanometers. It is believed that these nanochannels are formed at the zigzag and armchair faces between two adjacent crystallites and in the vicinity of defects and impurities. Mild burn‐off was found to improve performance in normalLi/LixC cells: QR is increased by 10–30%, QIR is generally decreased (for less than 6% burn‐off) and LixC6 anode degradation rate is much lower. Performance improvement is attributed to the formation of SEI chemically bonded to the surface carboxylic groups at the zigzag and armchair faces, and to accommodation of extra lithium at the zigzag, armchair, and other edge sites and nanovoids.
Novel biocompatible hybrid-material composed of iron-ion-cross-linked alginate with embedded protein molecules has been designed for the signal-triggered drug release. Electrochemically controlled oxidation of Fe(2+) ions in the presence of soluble natural alginate polymer and drug-mimicking protein (bovine serum albumin, BSA) results in the formation of an alginate-based thin-film cross-linked by Fe(3+) ions at the electrode interface with the entrapped protein. The electrochemically generated composite thin-film was characterized by electrochemistry and atomic force microscopy (AFM). Preliminary experiments demonstrated that the electrochemically controlled deposition of the protein-containing thin-film can be performed at microscale using scanning electrochemical microscopy (SECM) as the deposition tool producing polymer-patterned spots potentially containing various entrapped drugs. Application of reductive potentials on the modified electrode produced Fe(2+) cations which do not keep complexation with alginate, thus resulting in the electrochemically triggered thin-film dissolution and the protein release. Different experimental parameters, such as the film-deposition time, concentrations of compounds and applied potentials, were varied in order to demonstrate that the electrodepositon and electrodissolution of the alginate composite film can be tuned to the optimum performance. A statistical modeling technique was applied to find optimal conditions for the formation of the composite thin-film for the maximal encapsulation and release of the drug-mimicking protein at the lowest possible potential.
Biocompatible photoresponsive materials are of interest for targeted drug delivery, tissue engineering, 2D and 3D protein patterning, and other biomedical applications. We prepared light degradable hydrogels using a natural alginate polysaccharide cross-linked with iron(III) cations. The "hard" iron(III) cations used to cross-link the alginate hydrogel were found to undergo facile photoreduction to "soft" iron(II) cations in the presence of millimolar concentrations of sodium lactate. The "soft" iron(II) cations have a decreased ability to cross-link the alginate which results in dissolution of the hydrogel and the formation of a homogeneous solution. The photodegradation is done using long wave UV or visible light at neutral pH. The very mild conditions required for the photodegradation and the high rate at which it occurs suggest applications for iron(III) cross-linked alginate hydrogels as light-controlled biocompatible scaffolds.
A new approach to bioelectronic Sense-and-Act systems was developed with the use of modified electrodes performing sensing and substance-releasing functions. The sensing electrode was activated by biomolecular/biological signals ranging from small biomolecules to proteins and bacterial cells. The activated sensing electrode generated reductive potential and current, which stimulated dissolution of an Fe(3+)-cross-linked alginate matrix on the second connected electrode resulting in the release of loaded biochemical species with different functionalities. Drug-mimicking species, antibacterial drugs, and enzymes activating a biofuel cell were released and tested for various biomedical and biotechnological applications. The studied systems offer great versatility for future applications in controlled drug release and personalized medicine. Their future applications in implantable devices with autonomous operation are proposed.
We have prepared 5′-modified derivatives of adenosine and a corresponding (N)-methanocarba nucleoside series containing a bicyclo[3.1.0]hexane ring system in place of the ribose moiety. The compounds were examined in binding assays at three subtypes of adenosine receptors (ARs) and in functional assays at the A 3 AR. The H-bonding ability of a group of 9-riboside derivatives containing a 5′-uronamide moiety was reduced by modification of the NH, however these derivatives did not display the desired activity as selective A 3 AR antagonists, as occurs with 5′-N,Ndimethyluronamides. However, truncated (N)-methanocarba analogues lacking a 4′-hydroxymethyl group were highly potent and selective antagonists of the human A 3 AR. The compounds were synthesized from D-ribose using a reductive free radical decarboxylation of a 5′-carboxy intermediate. A less efficient synthetic approach began with L-ribose, which was similar to the published synthesis of (N)-methanocarba A 3 AR agonists. Compounds 33b -39b (N 6 -3-halobenzyl and related arylalkyl derivatives) were potent A 3 AR antagonists with binding K i values of 0.7 − 1.4 nM. In a functional assay of [ 35 S]GTPγS binding, 33b (3-iodobenzyl) completely inhibited stimulation by NECA with a K B of 8.9 nM. Thus, a highly potent and selective series of A 3 AR antagonists has been described.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.