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1.
Talanta ; 233: 122531, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215034

RESUMO

Exosomes, as a biomarker with enhancing tumor invasion and spread, play an essential role for lung cancer diagnosis, therapy, and prognosis. In this work, a novel electrochemical sensor was fabricated for detecting exosomes secreted by lung cancer cells based on polysaccharide-initiated ring-opening polymerization (ROP) and click polymerization. First, MPA formed a self-assembled monolayer on the gold electrode surface, and then anti-EGFR was immobilized on the electrode surface by amide bond. Subsequently, a lot of phosphate groups were introduced by the specific recognition between anti-EGFR and exosomes, then sodium alginate grafted Glycidyl propargyl ether (SA-g-GPE) prepared via ROP was attached to the exosomes through PO43-Zr4+-COOH coordination bond. After that, click polymerization was initiated by alkyne groups on the SA-g-GPE polymerization chain to realize highly sensitive detection of A549 exosomes. Under the optimum conditions, the fabricated sensor showed a good linear relationship between the logarithm of exosomes concentration and peak current in the range of 5 × 103 - 5 × 109 particles/mL, and the limit of detection (LOD) was as low as 1.49 × 102 particles/mL. In addition, this method had the advantages of high specificity, anti-interference, high sensitivity, simplicity, rapidity and green economy, which proposed a novel avenue for the detection of exosomes, and also had potential applications in early cancer diagnosis and biomedicine.


Assuntos
Técnicas Biossensoriais , Exossomos , Técnicas Eletroquímicas , Ouro , Limite de Detecção , Polimerização , Polissacarídeos
2.
Int J Mol Sci ; 22(11)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198821

RESUMO

Photo-polymerized hydrogels are ideally suited for stem-cell based tissue regeneration and three dimensional (3D) bioprinting because they can be highly biocompatible, injectable, easy to use, and their mechanical and physical properties can be controlled. However, photo-polymerization involves the use of potentially toxic photo-initiators, exposure to ultraviolet light radiation, formation of free radicals that trigger the cross-linking reaction, and other events whose effects on cells are not yet fully understood. The purpose of this study was to examine the effects of hydrogen sulfide (H2S) in mitigating cellular toxicity of photo-polymerization caused to resident cells during the process of hydrogel formation. H2S, which is the latest discovered member of the gasotransmitter family of gaseous signalling molecules, has a number of established beneficial properties, including cell protection from oxidative damage both directly (by acting as a scavenger molecule) and indirectly (by inducing the expression of anti-oxidant proteins in the cell). Cells were exposed to slow release H2S treatment using pre-conditioning with glutathione-conjugated-garlic extract in order to mitigate toxicity during the photo-polymerization process of hydrogel formation. The protective effects of the H2S treatment were evaluated in both an enzymatic model and a 3D cell culture system using cell viability as a quantitative indicator. The protective effect of H2S treatment of cells is a promising approach to enhance cell survival in tissue engineering applications requiring photo-polymerized hydrogel scaffolds.


Assuntos
Técnicas de Cultura de Células/métodos , Hidrogéis/farmacologia , Sulfeto de Hidrogênio/farmacologia , Engenharia Tecidual , Sobrevivência Celular/efeitos dos fármacos , Humanos , Luz , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos da radiação , Polimerização/efeitos dos fármacos , Polimerização/efeitos da radiação , Impressão Tridimensional , Tecidos Suporte , Cicatrização/efeitos dos fármacos , Cicatrização/efeitos da radiação
3.
Int J Mol Sci ; 22(13)2021 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-34206862

RESUMO

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule-substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.


Assuntos
Microscopia de Tunelamento/métodos , Compostos Organometálicos/química , Cristalização , Polimerização , Estresse Mecânico , Temperatura , Vácuo
4.
Molecules ; 26(10)2021 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-34065879

RESUMO

The modification of medical devices is an area that has attracted a lot of attention in recent years; particularly, those developments which search to modify existing devices to render them antimicrobial. Most of these modifications involve at least two stages (modification of the base material with a polymer graft and immobilization of an antimicrobial agent) which are both time-consuming and complicate synthetic procedures; therefore, as an improvement, this project sought to produce antimicrobial silicone (PDMS) in a single step. Using gamma radiation as both an energy source for polymerization initiation and as a source of reducing agents in solution, PDMS was simultaneously grafted with acrylic acid and ethylene glycol dimethacrylate (AAc:EGDMA) while producing antimicrobial silver nanoparticles (AgNPs) onto the surface of the material. To obtain reproducible materials, experimental variables such as the effect of the dose, the intensity of radiation, and the concentration of the silver salt were evaluated, finding the optimal reaction conditions to obtain materials with valuable properties. The characterization of the material was performed using electronic microscopy and spectroscopic techniques such as 13C-CPMAS-SS-NMR and FTIR. Finally, these materials demonstrated good antimicrobial activity against S. aureus while retaining good cell viabilities (above 90%) for fibroblasts BALB/3T3.


Assuntos
Acrilatos/química , Antibacterianos/química , Materiais Biocompatíveis/química , Raios gama , Nanopartículas Metálicas/química , Polimerização/efeitos da radiação , Silicones/química , Prata/química , Animais , Células 3T3 BALB , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Metacrilatos/química , Camundongos , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos
5.
Biomacromolecules ; 22(6): 2702-2717, 2021 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-34060815

RESUMO

When cellulose nanocrystals (CNCs) are isolated from cellulose microfibrils, the parallel arrangement of the cellulose chains in the crystalline domains is retained so that all reducing end-groups (REGs) point to one crystallite end. This permits the selective chemical modification of one end of the CNCs. In this study, two reaction pathways are compared to selectively attach atom-transfer radical polymerization (ATRP) initiators to the REGs of CNCs, using reductive amination. This modification further enabled the site-specific grafting of the anionic polyelectrolyte poly(sodium 4-styrenesulfonate) (PSS) from the CNCs. Different analytical methods, including colorimetry and solution-state NMR analysis, were combined to confirm the REG-modification with ATRP-initiators and PSS. The achieved grafting yield was low due to either a limited conversion of the CNC REGs or side reactions on the polymerization initiator during the reductive amination. The end-tethered CNCs were easy to redisperse in water after freeze-drying, and the shear birefringence of colloidal suspensions is maintained after this process.


Assuntos
Celulose , Nanopartículas , Polimerização , Água
6.
Int J Mol Sci ; 22(9)2021 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-34065133

RESUMO

Low-molecular-weight organic ammonium salts exert excellent antimicrobial effects by interacting lethally with bacterial membranes. Unfortunately, short-term functionality and high toxicity limit their clinical application. On the contrary, the equivalent macromolecular ammonium salts, derived from the polymerization of monomeric ammonium salts, have demonstrated improved antibacterial potency, a lower tendency to develop resistance, higher stability, long-term activity, and reduced toxicity. A water-soluble non-quaternary copolymeric ammonium salt (P7) was herein synthetized by copolymerizing 2-methoxy-6-(4-vinylbenzyloxy)-benzylammonium hydrochloride monomer with N, N-di-methyl-acrylamide. The antibacterial activity of P7 was assessed against several multidrug-resistant (MDR) clinical isolates of both Gram-positive and Gram-negative species. Except for colistin-resistant Pseudomonas aeruginosa, most isolates were susceptible to P7, also including some Gram-negative bacteria with a modified charge in the external membrane. P7 showed remarkable antibacterial activity against isolates of Enterococcus, Staphylococcus, Acinetobacter, and Pseudomonas, and on different strains of Escherichia coli and Stenotrophomonas maltophylia, regardless of their antibiotic resistance. The lowest minimal inhibitory concentrations (MICs) observed were 0.6-1.2 µM and the minimal bactericidal concentrations (MBC) were frequently overlapping with the MICs. In 24-h time-kill and turbidimetric studies, P7 displayed a rapid non-lytic bactericidal activity. P7 could therefore represent a novel and potent tool capable of counteracting infections sustained by several bacteria that are resistant to the presently available antibiotics.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Compostos de Benzilamônio/química , Compostos de Benzilamônio/farmacologia , Polímeros , Antibacterianos/síntese química , Bactérias/efeitos dos fármacos , Compostos de Benzilamônio/síntese química , Técnicas de Química Sintética , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Polimerização , Polímeros/química , Análise Espectral
7.
Colloids Surf B Biointerfaces ; 205: 111897, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34118533

RESUMO

Polydopamine (PDA), also known as synthetic melanin, is widely used as a biomimetic anchoring layer for the modification of various solid substrates. PDA is utilized for a wide range of biomedical, sensing and tribological applications, even though the polymer's precise covalent structure has not been completely revealed yet. Even more, it is not evident to which extent the chemical nature of the substrate, on which the layer is formed, influences and predetermines the covalent structure of resulting PDA. In this contribution, we have studied the growth of PDA using various surface-sensitive techniques such as spectroscopic ellipsometry, atomic force microscopy and X-ray photoelectron spectroscopy. We supplemented grazing angle attenuated total reflection FTIR spectroscopy with multivariate statistical analysis to further gain analytical power. We have particularly focused on the effects of polymerization time and substrate on the PDA structure. We found notable differences in the chemical composition of PDA formed on gold and on surfaces terminated with oxides/reactive hydroxides such as silicon and N-dopped-TiO2 in the early stages of the layer formation. At the later stages of layer formation, a merely unified chemical structure was observed independently on the type of substrate.


Assuntos
Indóis , Polímeros , Polimerização , Propriedades de Superfície
8.
J Biol Regul Homeost Agents ; 35(3): 965-974, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34080409

RESUMO

This study aims to explore the mechanism of cyclic tensile stress (CTS) on human chondrocytes (CHs) relating to the reactive oxygen species (ROS) generation and extracellular matrix (ECM) stability in vitro. A well-established CTS model with 5%, 10%, or 20% elongation was performed for CHs stretching. After CTS, the cell viability, total ROS level, main ECM components, matrix metalloproteinase (MMP), tissue inhibitor of metalloproteinase (TIMP), F-actin density, and some anti-oxidative enzymes were analyzed. Additionally, the antioxidant N-acetylcysteine (NAC) and cytochalasin D were used to suppress the ROS production and F-actin polymerization when the CHs underwent CTS, respectively. The treatment of 20% elongation-CST significantly decreased the CH viability and the expressions of collagen II, aggrecan, anti-oxidative enzymes and TIMP3/4, however, it increased the ROS accumulation, F-actin polymerization, and the expression of collagen I and MMP3/13. In contrast, the application of NAC and cytochalasin D could partly rescue the CHs from the injury caused by the high CTS. Therefore, high CTS disrupts the ECM by remodeling the F-actin cytoskeleton and promoting ROS production. Cytochalasin D and NAC are effective in rejecting F-actin cytoskeleton polymerization, and ROS accumulation through a potential synergetic process, which alleviates the ECM injury caused by High CTS.


Assuntos
Actinas , Condrócitos , Citoesqueleto de Actina , Células Cultivadas , Matriz Extracelular , Humanos , Polimerização , Espécies Reativas de Oxigênio
9.
J Cell Sci ; 134(11)2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-34096607

RESUMO

Axons and dendrites are distinguished by microtubule polarity. In Drosophila, dendrites are dominated by minus-end-out microtubules, whereas axons contain plus-end-out microtubules. Local nucleation in dendrites generates microtubules in both orientations. To understand why dendritic nucleation does not disrupt polarity, we used live imaging to analyze the fate of microtubules generated at branch points. We found that they had different rates of success exiting the branch based on orientation: correctly oriented minus-end-out microtubules succeeded in leaving about twice as often as incorrectly oriented microtubules. Increased success relied on other microtubules in a parallel orientation. From a candidate screen, we identified Trim9 and kinesin-5 (Klp61F) as machinery that promoted growth of new microtubules. In S2 cells, Eb1 recruited Trim9 to microtubules. Klp61F promoted microtubule growth in vitro and in vivo, and could recruit Trim9 in S2 cells. In summary, the data argue that Trim9 and kinesin-5 act together at microtubule plus ends to help polymerizing microtubules parallel to pre-existing ones resist catastrophe.


Assuntos
Polaridade Celular , Dendritos , Cinesina/genética , Proteínas Associadas aos Microtúbulos/genética , Microtúbulos , Polimerização
10.
Biomacromolecules ; 22(7): 3128-3137, 2021 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-34137600

RESUMO

Polymersomes are multicompartmental vesicular nano-objects obtained by self-assembly of amphiphilic copolymers. When prepared in the aqueous phase, they are composed of a hydrophobic bilayer enclosing water. Although such fascinating polymeric nano-objects have been widely reported with synthetic block copolymers, their formation from polysaccharide-based copolymers remains a significant challenge. In the present study, the powerful platform technology known as polymerization-induced self-assembly was used to prepare in situ pure vesicles from a polysaccharide-grafted copolymer: dextran-g-poly(2-hydroxypropyl methacrylate) (Dex-g-PHPMA). The growth of the PHPMA grafts was performed with a dextran-based macromolecular chain transfer agent in water at 20 °C using photomediated reversible addition fragmentation chain transfer polymerization at 405 nm. Transmission electron microscopy, cryogenic electron microscopy, small-angle X-ray scattering, atomic force microscopy, and dynamic light scattering revealed that amphiphilic Dex-g-PHPMAX = 100-300 (X is the targeted average degree of polymerization, Xn̅, of each graft at full conversion) exhibit remarkable self-assembly behavior. On the one hand, vesicles were obtained over a wide range of solid concentrations (from 2.5% to 13.5% w/w), which can facilitate posterior targeting of such rare morphology. On the other hand, the extension of Xn̅ induces an increase in the vesicle membrane thickness, rather than a morphological evolution (spherical micelles to cylinders to vesicles).


Assuntos
Micelas , Polímeros , Interações Hidrofóbicas e Hidrofílicas , Polimerização , Polissacarídeos
11.
Biomacromolecules ; 22(7): 3119-3127, 2021 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-34152744

RESUMO

Molecular mobility is important for interactions of biofunctional polymers with target molecules. Monomer structures for synthetic biofunctional polymers are usually selected based on their compatibility with polymerization systems, whereas the influence of monomer structures on the interaction with target molecules is hardly considered. In this report, we evaluate the correlation between the monomer structures of glycopolymers and their interactions with concanavalin A (ConA) with respect to the molecular mobility. Two types of glycopolymers bearing mannose are synthesized with acrylamide or acrylate monomers. Despite the similar structures, except for amide or ester bonds in the side chains, the acrylate-type glycopolymers exhibit stronger interaction with ConA both in the isothermal titration calorimetry measurement and in a hemagglutination inhibition assay. Characterization of the acrylate-type glycopolymers suggests that the higher binding constant arises from the higher molecular mobility of mannose units, which results from the rotational freedom of ester bonds in their side chains.


Assuntos
Polímeros , Concanavalina A , Ligantes , Substâncias Macromoleculares , Polimerização
12.
Soft Matter ; 17(26): 6394-6403, 2021 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-34132302

RESUMO

Hydrogel surfaces are of great importance in numerous applications ranging from cell-growth studies and hydrogel-patch adhesion to catheter coatings and contact lenses. A common method to control the structure and mechanical/tribological properties of hydrogel surfaces is by synthesizing them in various mold materials, whose influence has been widely ascribed to their hydrophobicity. In this work, we examine possible mechanisms for this "mold effect" on the surface of hydrogels during polymerization. Our results for polyacrylamide gels clearly rule out the effect of mold hydrophobicity as well as any thermal-gradient effects during synthesis. We show unequivocally that oxygen diffuses out of certain molding materials and into the reaction mixture, thereby inhibiting free-radical polymerization in the vicinity of the molding interface. Removal of oxygen from the system results in homogeneously cross-linked hydrogel surfaces, irrespective of the substrate material used. Moreover, by varying the amount of oxygen at the surface of the polymerizing solutions using a permeable membrane we are able to tailor the surface structures and mechanical properties of PAAm, PEGDA and HEMA hydrogels in a controlled manner.


Assuntos
Hidrogéis , Oxigênio , Interações Hidrofóbicas e Hidrofílicas , Polimerização
13.
J Chromatogr A ; 1651: 462337, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34157476

RESUMO

Here, a m-xylene bisphosphonate immobilized tentacle-type cellulose monolith (BP-PCM) is prepared by atom transfer radical polymerization for lysozyme purification. In the preparation, the m-xylene bisphosphonate was anchored glycidyl methacrylate and then polymerized to enhance the flexibility of the ligands to improve lysozyme adsorption capacity, and glycerol monomethacrylate serves as spacer to further optimize the layers structure and ligands density of the grafted tentacles for satisfactory adsorption capacity. The maximum static and dynamic adsorption capacity (10% breakthrough) of BP-PCM reach to 169.6 and 102.6 mg mL-1, respectively. Moreover, BP-PCM displays weak nonspecific adsorption and is able to successfully enrich lysozyme from diluted chicken egg white, indicating the excellent selectivity. The results demonstrated that BP-PCM is promising for use as high-capacity protein chromatography.


Assuntos
Celulose/química , Técnicas de Química Analítica/métodos , Cromatografia , Difosfonatos/química , Muramidase/isolamento & purificação , Adsorção , Técnicas de Química Analítica/instrumentação , Compostos de Epóxi/química , Ligantes , Metacrilatos/química , Muramidase/química , Polimerização , Porosidade
14.
Talanta ; 232: 122182, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34074380

RESUMO

Lanthanide nanoprobes have attracted extensive attention for applications in cellular imaging and biological sensing. Herein, water-dispersible europium (III)-based (Eu(III)-based) nanoprobes were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly (PISA) of hydrophobic monomers (Eu(III)-containing monomer and methyl methacrylate (MMA)) using hydrophilic macro-chain transfer agent poly(PEGMA)-CTA. The resulted poly(PMEu) nanoprobes showed spherical in shape in good monodispersity with average diameters of around 210 nm. The poly(PMEu) nanoprobles excellent aqueous dispersity, high aqueous stability and good luminescence properties with quantum yields of 37.21% and fluorescence lifetime of 312.4 µs. Moreover, the poly(PMEu) nanoprobes exhibited good cellular biocompatibility with cell viabilities of 88.2% and high fluorescence intensity for in vitro cellular imaging. The present approach provides a facile strategy for fabrication of luminescent Eu(III)-based nanoprobes with great potential applications for biological imaging.


Assuntos
Európio , Nanopartículas , Polimerização , Polímeros , Água
15.
Talanta ; 232: 122419, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34074406

RESUMO

Monodisperse molecularly imprinted polymers (MIPs) for warfarin (WF), 4'-chlorowarfarin (CWF), 4'-bromowarfarin (BWF), 4'-nitrowarfarin (NWF) and 4'-methylwarfarin (MWF) (MIPWF, MIPCWF, MIPBWF, MIPNWF and MIPMWF, respectively) were prepared using 4-vinylpyridine (4-VPY) and ethylene glycol dimethacrylate as a functional monomer and crosslinker, respectively, by multi-step swelling and polymerization. The retention and molecular-recognition properties of those MIPs were evaluated in HILIC, and reversed- and normal-phase modes. According to 1H NMR studies, one-to-three complex formation of one WF or CWF molecule with three 4-VPY molecules occurred. Via computational approaches, the intermolecular interaction modes and energies between WF derivatives and 4-VPYs were evaluated by semi-empirical quantum chemistry methods and density functional theory calculations. Three major possible hydrogen bonding interaction modes were identified: the interactions between the 4-hydroxy group, α-proton (methylene C-H) and α-proton (methyl C-H) of the WF derivative and the nitrogen atoms of 4-VPYs. In HILIC and normal-phase modes, the interaction energies showed satisfactory correlations with the retention factors of the WF derivatives. In reversed-phase mode, the retention factors of the WF derivatives were described by the hydrophobicity and the acidity of the 4-hydroxy groups of the WF derivatives. These results demonstrate that three hydrogen bonding interactions in HILIC and normal-phase modes, and hydrogen bonding or ionic interactions and hydrophobic interactions in reversed-phase mode play important roles in the retention and molecular-recognition of the WF derivatives on MIPs. Furthermore, MIPBWF was successfully applied to the determination of WF in human serum by column-switching LC with high accuracy, precision and selectivity and without template-leakage problems.


Assuntos
Impressão Molecular , Polímeros Molecularmente Impressos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Polimerização , Polímeros , Varfarina
16.
AAPS PharmSciTech ; 22(5): 181, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-34129154

RESUMO

In this study, two hydrophilic polymers hydroxypropyl methyl cellulose and beta-cyclodextrin (ß-CD) are used to synthesize highly responsive and spongy polymeric matrices. Porous and stimulus-responsive polymeric network was developed to improve the solubility of acyclovir (ACV) at significant level. Grafting was successfully carried out by free radical polymerization technique. Spongy matrices were characterized by percentage entrapment efficiency, drug loading, solubility studies, FTIR, powder X-ray diffraction, TGA, DSC, XRD, SEM, swelling studies, and in vitro studies. Acute oral toxicity studies were conducted to determine the safety of oral administration of prepared HPMC-ßCD-g-poly(AMPS) formulation. Porous and spongy structures were depicted in SEM images. Complex formation and thermal stability of constituents and drug (ACV) were analyzed by FTIR, TGA, and DSC spectra. XRD analysis revealed reduction in acyclovir crystallinity in spongy matrices. Particle size of optimized formulation was found in the range of 197 ± 2.55 nm. The momentous difference with reference product committed that drug solubility and release characteristics were markedly enhanced by the developed spongy matrices. Toxicity studies endorsed that developed spongy matrices were non-toxic and compatible to biological system. The efficient method of preparation, enhanced solubility, excellent physico-chemical characteristics, high dissolution, and non-toxic HPMC-ßCD-g-poly(AMPS) spongy matrices may be a promising approach for oral delivery of poorly soluble drugs.


Assuntos
Acrilamidas/síntese química , Aciclovir/síntese química , Alcanossulfonatos/síntese química , Derivados da Hipromelose/síntese química , Polimerização , beta-Ciclodextrinas/síntese química , Acrilamidas/administração & dosagem , Aciclovir/administração & dosagem , Administração Oral , Alcanossulfonatos/administração & dosagem , Animais , Antivirais/administração & dosagem , Antivirais/síntese química , Avaliação Pré-Clínica de Medicamentos/métodos , Derivados da Hipromelose/administração & dosagem , Masculino , Tamanho da Partícula , Polímeros/administração & dosagem , Polímeros/síntese química , Coelhos , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Difração de Raios X/métodos , beta-Ciclodextrinas/administração & dosagem
17.
Molecules ; 26(9)2021 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-34067052

RESUMO

Trends in the dynamically developing application of biocatalysis for the synthesis and modification of polymers over the past 5 years are considered, with an emphasis on the production of biodegradable, biocompatible and functional polymeric materials oriented to medical applications. The possibilities of using enzymes not only as catalysts for polymerization but also for the preparation of monomers for polymerization or oligomers for block copolymerization are considered. Special attention is paid to the prospects and existing limitations of biocatalytic production of new synthetic biopolymers based on natural compounds and monomers from biomass, which can lead to a huge variety of functional biomaterials. The existing experience and perspectives for the integration of bio- and chemocatalysis in this area are discussed.


Assuntos
Biocatálise , Polímeros/síntese química , Enzimas/metabolismo , Polimerização , Polímeros/química , Engenharia de Proteínas , Publicações
18.
Soft Matter ; 17(25): 6160-6167, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-34085082

RESUMO

Reaction-diffusion systems are one of the models of the formation process with various patterns found in nature. Inspired by natural pattern formation, several methods for designing artificial chemical reaction-diffusion systems have been proposed. DNA is a suitable building block to build such artificial systems owing to its programmability. Previously, we reported a line pattern formed due to the reaction and diffusion of synthetic DNA; however, the width of the line was too wide to be used for further applications such as parallel and multi-stage pattern formations. Here, we propose a novel method to programme a reaction-diffusion system in a hydrogel medium to realise a sharp line capable of forming superimposed and cascaded patterns. The mechanism of this system utilises a two-segment polymerisation of DNA caused by hybridisation. To superimpose the system, we designed orthogonal DNA sequences that formed two lines in different locations on the hydrogel. Additionally, we designed a reaction to release DNA and form a cascade pattern, in which the third line appears between the two lines. To explain the mechanism of our system, we modelled the system as partial differential equations, whose simulation results agreed well with the experimental data. Our method to fabricate cascaded patterns may inspire combinations of DNA-based technologies and expand the applications of artificial reaction-diffusion systems.


Assuntos
DNA , Hidrogéis , Simulação por Computador , Difusão , Polimerização
19.
Nat Commun ; 12(1): 3451, 2021 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-34103486

RESUMO

Several cell-surface receptors for neurotoxic forms of amyloid-ß (Aß) have been described, but their molecular interactions with Aß assemblies and their relative contributions to mediating Alzheimer's disease pathology have remained uncertain. Here, we used super-resolution microscopy to directly visualize Aß-receptor interactions at the nanometer scale. We report that one documented Aß receptor, PrPC, specifically inhibits the polymerization of Aß fibrils by binding to the rapidly growing end of each fibril, thereby blocking polarized elongation at that end. PrPC binds neurotoxic oligomers and protofibrils in a similar fashion, suggesting that it may recognize a common, end-specific, structural motif on all of these assemblies. Finally, two other Aß receptors, FcγRIIb and LilrB2, affect Aß fibril growth in a manner similar to PrPC. Our results suggest that receptors may trap Aß oligomers and protofibrils on the neuronal surface by binding to a common molecular determinant on these assemblies, thereby initiating a neurotoxic signal.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Amiloide/metabolismo , Neurotoxinas/química , Multimerização Proteica , Receptores de Superfície Celular/metabolismo , Animais , Benzotiazóis/metabolismo , Calmodulina/metabolismo , Humanos , Cinética , Camundongos , Modelos Biológicos , Polimerização , Príons/metabolismo , Ligação Proteica , Receptores de IgG/metabolismo , Receptores Imunológicos/metabolismo
20.
J Oral Sci ; 63(3): 275-279, 2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34148925

RESUMO

PURPOSE: To evaluate the influence of polymerization methods and a metal priming agent on the bond strength between gold alloy for metal ceramic restorations and dual-cure-type resin luting agents, and on the strength and hardness of the luting agents. METHODS: A total of 154 disks cast by a gold alloy were treated with or without a metal priming agent. One of the three luting agents was applied on the disk. The luting agent was either chemically or dual-polymerized. The shear bond strength was measured both before and after thermocycling. In addition, scanning electron microscope (SEM) observation, flexural strength test, and Knoop hardness test were performed. RESULTS: Significant differences among the luting agents were observed in terms of bond strength and flexural strength. Significant differences between chemically and dual-polymerized luting agents were observed regarding shear bond strength, flexural strength, and Knoop hardness before thermocycling. The application of the priming agent was effective only for a luting agent. CONCLUSION: Both bond strength and flexural strength differed among three luting agents. The effect of the priming agent on bond strength differed among the luting agents. Both the bond and flexural strength of a chemically polymerized luting agent differed before or after thermocycling.


Assuntos
Colagem Dentária , Ligas de Ouro , Cimentos Dentários , Teste de Materiais , Polimerização , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
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