Search results for "modification"
showing 10 items of 853 documents
Preparation and preliminary biological screening of cholic acid–juvenoid conjugates
2020
Abstract Steroidal compounds have been utilized as carriers and for modification of physico-chemical properties of model biologically active secondary alcohols – juvenoids. Juvenoids are juvenile hormone analogues – environmentally safe insecticides, possessing significant biological activity towards different arthropods groups in focus on insect pest species. Structure modification of juvenoids plays important role to control the rate of liberation and decomposition of juvenoid in digestive system and can also play important role in the mode of action towards selected insect. This study presents an approach to the synthesis of steroidal monomers and dimers carrying one and two molecules of…
Modification of halloysite lumen with dopamine derivatives as filler for antibiofilm coating
2023
Hypothesis: Development of nanocomposite coating with antibiofilm properties is of fundamental importance to efficient fight biofilm formation preventing infections in biomedical area. In this context, halloysite nanotubes (HNTs), biocompatible and low-cost clay mineral, have been efficiently used as filler for different polymeric matrices affording several nanocomposites with appealing antimicrobial properties. The modification of HNTs surfaces represents a valuable strategy to improve the utilization of the clay for biological purposes. Experiments: Herein, the covalent modification of the HNTs lumen with properly designed dopamine derivatives with different perfluoroalkyl chain length is…
Surface modification of AISI-304 steel by ZnO synthesis using cathodic cage plasma deposition
2021
Abstract Zinc-oxide (ZnO), a solid lubricant coating, can increase the wear resistance of steels by working as a self-lubricant. In this study, ZnO film is synthesized using the cathodic cage plasma deposition (CCPD) technique, using galvanized steel cathodic cage (steel cage with zinc coating). The effect of gas composition (H2 is added in Ar-O2) is investigated to optimize the film properties. The surface hardness is increased more than twice in each processing condition. The deposited film shows ZnO phases for samples treated with low hydrogen contents and a combination of ZnO and magnetite phase (Fe3O4) with higher hydrogen contents. The thickness of film reduced from 1.28 μm to 0.5 μm …
Low-fouling, mixed-charge poly-L-lysine polymers with anionic oligopeptide side-chains
2018
Biosensors and biomedical devices require antifouling surfaces to prevent the non-specific adhesion of proteins or cells, for example, when aiming to detect circulating cancer biomarkers in complex natural media (e.g., in blood plasma or serum). A mixed-charge polymer was prepared by the coupling of a cationic polyelectrolyte and an anionic oligopeptide through a modified "grafting-to" method. The poly-l-lysine (PLL) backbone was modified with different percentages (y%) of maleimide-NHS ester chains (PLL-mal(y%), from 13% to 26%), to produce cationic polymers with specific grafting densities, obtaining a mixed-charge polymer. The anionic oligopeptide structure (CEEEEE) included one cysteine…
Colloidal stability of halloysite clay nanotubes
2019
Abstract The colloidal stability of halloysite clay nanotubes dispersion is reviewed showing the strategy and the mechanism to obtain stable systems in water and apolar solvents. The selective modification of halloysite inner/outer surfaces can be achieved by exploiting electrostatic interactions. The adsorption of anionic surfactants onto the halloysite cavity allows generating inorganic cylindrical micelles that can be separated from the solvent. On the other hand, the functionalization of halloysite shell by positively charged surfactants drives to obtain stable water-in-oil emulsions. The interactions with ionic and nonionic polymers alters the dispersability of halloysite due to electr…
Synthesis of AB and ABA block copolymers as compatibilizers in nylon 6/polycarbonate blends
1996
Nylon 6 (Ny6) and Bisphenol A polycarbonate (PC) are immiscible and form biphasic blends. To improve the compatibility of Ny6 and PC several ABA and AB Ny6/PC block copolymers were synthesized, and their compatibilizing behavior on the blends were tested. Block copolymers were prepared by reacting monoamino- or diamino-terminated Ny6 homopolymers with high molecular weight PC at 130°C in anhydrous DMSO. The reaction of diamino- and monoamino-terminated Ny6 with polycarbonate produces block copolymers of the type PC-Ny6-PC (ABA) and PC-Ny6 (AB), respectively, plus a certain amount of unconverted PC degradated to lower molecular weights. To separate the block copolymer from the unconverted PC…
Variable presence of 5-methylcytosine in commercial RNA and DNA
2015
Nucleoside methylations and other nucleic acid modifications have recently encountered a surge in interest, prompted, among other things, by the detection of methylation and active demethylation of DNA and mRNA by similar mechanisms. In DNA, deoxycytidine methylation by Dnmt enzymes generates 5-methyldeoxycytidine,1 an important epigenetic mark that typically causes inactivation of transcription of the methylated promoter region. Recent exciting developments have shown that these marks are not concrete-cast, but can be actively removed by the oxidative action of TET enzymes,2 which generate, through a series of 2-electron oxidations, first hydroxymethylcytidine (hm5C), then formyldeoxycytid…
Molecular Proteomics and Signalling of Human Platelets in Health and Disease
2021
Platelets are small anucleate blood cells that play vital roles in haemostasis and thrombosis, besides other physiological and pathophysiological processes. These roles are tightly regulated by a complex network of signalling pathways. Mass spectrometry-based proteomic techniques are contributing not only to the identification and quantification of new platelet proteins, but also reveal post-translational modifications of these molecules, such as acetylation, glycosylation and phosphorylation. Moreover, target proteomic analysis of platelets can provide molecular biomarkers for genetic aberrations with established or non-established links to platelet dysfunctions. In this report, we review …
Rapid formation of plasma protein corona critically affects nanoparticle pathophysiology
2013
In biological fluids, proteins bind to the surface of nanoparticles to form a coating known as the protein corona, which can critically affect the interaction of the nanoparticles with living systems. As physiological systems are highly dynamic, it is important to obtain a time-resolved knowledge of protein-corona formation, development and biological relevancy. Here we show that label-free snapshot proteomics can be used to obtain quantitative time-resolved profiles of human plasma coronas formed on silica and polystyrene nanoparticles of various size and surface functionalization. Complex time- and nanoparticle-specific coronas, which comprise almost 300 different proteins, were found to …
Anti-oxidative effects and harmlessness of asymmetric Au@Fe3O4 Janus particles on human blood cells
2014
AbstractThe physical properties of asymmetric Janus particles are highly promising for future biomedical applications. However, only a few data is available on their biological impact on human cells. We investigated the biological impact of different Au@Fe3O4 Janus particle formulations in vitro to analyse specific uptake modalities and their potential cytotoxic effects on human cells of the blood regarding intravenous injection. We demonstrate that Au@Fe3O4 Janus particles exhibit a similar or even better biocompatibility compared to the well-studied spherical iron oxide nanoparticles. The impact of Janus particles on cells depends mainly on three factors. (1) Surface functionalization: NH…