RESUMO
Cellulose modified hydrogels can be produced directly from raw biopolymers in novel cellulose solvents such as NaOH/urea aqueous solution. The effect of cellulose characteristics on the synthesis of a cellulose-graft-(net-poly(acrylamide-co-acrylic acid)) and its performance as water absorbent/methylene blue dye removal material is analyzed. Three cellulose samples, one analytical grade and two obtained from teak wood sawdust with different pretreatments (one alkaline and the other, a novel one known as (gas phase) acid pretreatment) were compared. The starting raw celluloses were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and viscosity in cupri ethylenediamine hydroxide (CED) solution, whereas the chemically modified materials were characterized by SEM, FTIR, and TGA. The pretreatment used influences composition, crystallinity index and degree of polymerization (DP) of the cellulose obtained. The modified material produced with cellulose from alkaline pretreatment showed the highest swelling ratio in water absorption tests at room temperature (12,714 %); in contrast, the one with cellulose from acid pretreatment showed the lowest swelling ratio (7,470 %). However, this difference is not so significative in dye removal tests, where absorption capacity is 139 and 140 mg/g, respectively. The results indicate that cellulose composition, particularly structures with significant hemicellulose and lignin remaining content, has a major effect on the performance of modified materials for water absorption, and degree of polymerization has a major effect on adsorption capacity of methylene blue.
Assuntos
Celulose , Corantes , Lignina , Água , Madeira , Lignina/química , Celulose/química , Água/química , Madeira/química , Corantes/química , Resinas Acrílicas/química , Azul de Metileno/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , Purificação da Água/métodos , Poluentes Químicos da Água/química , Acrilamidas/químicaRESUMO
Aim: To investigate whether medical devices coated with a synthesized nanocomposite of poly(methylmethacrylate-co-dimethyl acrylamide) (PMMDMA) and silver nanoparticles (AgNPs) could improve their antibiofilm and antimicrobial activities. We also investigated the nanocomposite's safety. Materials & methods: The nanocomposite was synthesized and characterized using analytical techniques. Medical devices coated with the nanocomposite were evaluated for bacterial adhesion and hemolytic activity in vitro. Results: The nanocomposite formation was demonstrated with the incorporation of AgNPs into the polymer matrix. The nanocomposite proved to be nonhemolytic and significantly inhibited bacterial biofilm formation. Conclusion: The PMMDMA-AgNPs nanocomposite was more effective in preventing biofilm formation than PMMDMA alone and is a promising strategy for coating medical devices and reducing mortality due to hospital-acquired infections.
[Box: see text].
Assuntos
Biofilmes , Nanopartículas Metálicas , Nanocompostos , Prata , Biofilmes/efeitos dos fármacos , Prata/química , Prata/farmacologia , Nanocompostos/química , Nanopartículas Metálicas/química , Humanos , Antibacterianos/farmacologia , Antibacterianos/química , Aderência Bacteriana/efeitos dos fármacos , Equipamentos e Provisões/microbiologia , Hemólise/efeitos dos fármacos , Acrilamidas/química , Acrilamidas/farmacologiaRESUMO
OBJECTIVES: Acrylamides were shown to significantly improve bonding stability in adhesive restorations, but the reinforcement mechanism has not been fully elucidated. We tested the hypothesis that hydrogen bonding reinforcement of the collagen network (with secondary or tertiary acrylamides), as well as degree of crosslinking of the polymer network (with di- or tri-functional acrylamides), can be two of the factors at play. METHODS: Two-step total etch adhesives comprising UDMA (60 wt%) and 40 wt% of: TAAEA, TMAAEA (secondary, tertiary tri-acrylamides), BAAP, DEBAAP (secondary, tertiary di-acrylamides) or HEMA (mono-methacrylate - control) were formulated. Simulated composite restorations (n = 5) were tested after cyclic mechanical and biological (S. mutans biofilm) challenges. Gap formation before and after aging was assessed with SEM imaging. Micro-tensile bond strength (µTBS, n = 6) was assessed after seven-day incubation in water or S. mutans-containing culture medium. Collagen reinforcement was assessed with hydroxyproline assay (n = 10) and rheology (n = 3). Data were analyzed with one-way/two-way ANOVA/Tukey's test (alpha=5%). RESULTS: Gap formation increased and bond strength decreased for all monomers after biofilm incubation (p < 0.001). Except for DEBAAP, secondary and tertiary di/tri-acrylamides showed lower occlusal gap width values, but no significant differences overall gap length compared to HEMA. µTBS increased for tri-acrylamides compared with HEMA. Samples treated with multi-acrylamides had lower concentration of hydroxyproline (by-product of collagen degradation) (p < 0.001), except for DEBAAP, which showed values close to HEMA (p > 0.05). Dentin shear modulus increased for all acrylamides after 72 h, especially TMAAEA. SIGNIFICANCE: In general, multi-acrylamides promote collagen reinforcement, leading to reduced gap formation, and stabilize the bond strength under physiological conditions.
Assuntos
Acrilamidas , Colágeno , Colagem Dentária , Teste de Materiais , Resistência à Tração , Colágeno/química , Acrilamidas/química , Metacrilatos/química , Resinas Compostas/química , Reologia , Microscopia Eletrônica de Varredura , Ligação de Hidrogênio , Propriedades de Superfície , Análise do Estresse Dentário , Cimentos de Resina/química , PoliuretanosRESUMO
Stimulus-responsive nanoparticles stand out in studies for cancer treatment since these systems can promote a selective release of the drug in tumor tissues and cells, minimizing the effects caused by conventional chemotherapy. Dextran-graft-poly (N-isopropylacrylamide) copolymers were synthesized via Schiff base formation. The synthesis of copolymers was confirmed by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (NMR) and the analyses of dynamic light scattering (DLS) showed that the copolymers were thermal and pH dual-responsive. The chemotherapy drug doxorubicin (DOX) was conjugated to the copolymers via Schiff base formation, obtaining nanoparticles by self-assembling with size smaller than 130 nm. A higher percentage of doxorubicin was released at pH 5.0 (59.1 ± 2.1%) compared to physiological pH (34.9 ± 4.8%), confirming a pH-sensitive release profile. The in vitro cytotoxicity assay demonstrated that DOX-loaded nanoparticles can inhibit cancer cell proliferation and promote reduced cytotoxicity in non-tumor cells. The D45kP30k-DOX nanoparticles induced morphological changes in HCT-116 cells suggesting cell death and the cell uptake assay indicated that the nanoparticles can be internalized by endocytosis. Therefore, DOX-loaded nanoparticles exhibited potential as smart systems for cancer treatment.
Assuntos
Acrilamidas/química , Dextranos/química , Doxorrubicina/farmacologia , Pró-Fármacos/farmacologia , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Doxorrubicina/química , Células HCT116 , Humanos , Concentração de Íons de Hidrogênio , Camundongos , Micelas , Pró-Fármacos/química , Bases de Schiff/químicaRESUMO
Transport of therapeutics across the blood-brain barrier (BBB) is a fundamental requirement for effective treatment of numerous brain diseases. However, most therapeutics (>500 Da) are unable to permeate through the BBB and do not achieve therapeutic doses. Nanoparticles (NPs) are being investigated to facilitate drug delivery to the brain. Here, we investigate the effect of nanoparticle stiffness on NP transport across an in vitro BBB model. To this end, fluorescently labeled poly(N-isopropylmethacrylamide) (p(NIPMAM)) nanogels' stiffness was varied by the inclusion of 1.5 mol% (NG1.5), 5 mol% (NG5), and 14 mol% (NG14) N,N'-methylenebis(acrylamide) (BIS) cross-linker and nanogel uptake and transcytosis was quantified. The more densely cross-linked p(NIPMAM) nanogels showed the highest level of uptake by polarized brain endothelial cells, whereas the less densely cross-linked nanogels demonstrated the highest transcytotic potential. These findings suggest that nanogel stiffness has opposing effects on nanogel uptake and transcytosis at the BBB.
Assuntos
Barreira Hematoencefálica , Nanogéis/química , Acrilamidas/química , Linhagem Celular , Endotélio Vascular/citologia , Corantes Fluorescentes/química , Humanos , Técnicas In Vitro , Polímeros/químicaRESUMO
The influences of the hydrophilic chain length, morphology and chemical nature have been probed with regard to the adsorption of model proteins onto the surface of soft nanoparticles (crew-cut micelles and polymersomes). The investigations were based on assemblies manufactured from PEOm-b-PLAn (poly(ethylene oxide)-b-poly(lactic acid)), which is a well-established block copolymer platform towards the manufacturing of drug delivery vehicles, and PHPMAm-b-PDPAn (poly([N-(2-hydroxypropyl)]methacrylamide)-b-poly[2-(diisopropylamino)ethyl methacrylate]), which is pH-responsive and therefore potentially able to target damaged cells in slightly acid microenvironments. Besides, protein adsorption onto PHPMA-stabilized nanoparticles has been seldom explored up-to-date. The morphologies were produced using two different approaches (nanoprecipitation and thin-film hydration) and afterwards, the protein-repelling property of the assemblies in model protein environments (BSA - bovine serum albumin, lysozyme and IgG - immunoglobulin G) was evaluated. We report that, regardless the morphology, PHPMA35-b-PDPA42 block copolymer assemblies are highly stable with negligible protein binding. On the other hand, PEOm-b-PLAn nanostructures are susceptible to protein adsorption and the phenomenon is protein-dependent. The nanoparticles are more susceptible to adsorption of the model positively charged biomacromolecule (lysozyme). The adsorption phenomenon is thermodynamically complex with simultaneous endothermic and exothermic processes involved. Although the experimental data highlight that qualitatively the morphology plays negligible effects on the event, fluorescence spectroscopy measurements evidenced that the binding is stronger onto the surface of nanoparticles stabilized by shorter hydrophilic shells. Nevertheless, the adsorption does not affect the secondary structure of the model proteins as confirmed by circular dichroism spectroscopy. Overall, by comparing soft nanoparticles stabilized by PEO and PHPMA, the latter is herein proved to be a better choice towards the manufacturing of non-fouling structures (either core-shell or hollow spheres) where even a reasonably short hydrophilic chain confers outstanding protein-repelling feature.
Assuntos
Acrilamidas/química , Nanopartículas/química , Polímeros/química , Proteínas/química , Adsorção , Tamanho da Partícula , Propriedades de Superfície , TermodinâmicaRESUMO
In this work, we report the synthesis of graft copolymers based on casein and N-isopropylacrylamide, which can self-assemble into biodegradable micelles of approximately 80 nm at physiological conditions. The obtained copolymers were degraded by trypsin, an enzyme that is overexpressed in several malignant tumors. Moreover, graft copolymers were able to load doxorubicin (Dox) by ionic interaction with the casein component. In vitro release experiments showed that the in situ assembled micelles can maintain the cargo at plasma conditions but release Dox immediately after their exposition at pH 5.0 and trypsin. Cellular uptake and cytotoxicity assays revealed the efficient delivery to the nucleus and antiproliferative efficacy of Dox in the breast cancer cell line MDA231. Both delivery and therapeutic activity were enhanced in presence of trypsin. Overall, the prepared micelles hold a great potential for their utilization as dual responsive trypsin/pH drug delivery system.
Assuntos
Acrilamidas/química , Antineoplásicos/química , Caseínas/química , Doxorrubicina/química , Portadores de Fármacos/química , Polímeros/química , Temperatura , Antineoplásicos/farmacologia , Transporte Biológico , Linhagem Celular Tumoral , Portadores de Fármacos/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Polímeros/metabolismoRESUMO
In this work, a novel dual-response hydrogel for enhanced bone repair following multiple fractures was investigated. The conventional treatment of multiple bone fracture consists on removing smaller bone fragments from the body in a surgery, followed by the fixation of the bone using screws and plates. This work proposes an alternative for this treatment via in situ UV-initiated radical polymerization of a novel IPN hydrogel composed of PAA/P(NiPAAM-co-PEGDMA) incorporated with ceramic additives. The influence of different additives on mechanical properties and sensitivity of the polymer, as well as the prepolymer mixture, were investigated in order to analyse the suitability of the composites for bone healing applications. This material exhibited an interpenetrating network, confirmed by FTIR, with ceramics particles dispersed in between the polymer network. These structures presented high strength by tensile tests, sensitivity to pH and temperature and a decrease on Tg values of NiPAAm depending on the amount of PEGDMA and ceramics added; although, the addition of ceramics to these composites did not decrease their stability drastically. Finally, cytotoxicity tests revealed variations on the toxicity, whereas the addition of TCP presented to be non-toxic and that the cell viability increased when ceramics additives were incorporated into the polymeric matrix with an increased reporter activity of NF-κB, associated with aiding fibroblast adhesion. Hence, it was possible to optimise feedstock ratios to increase the applicability of the prepolymer mixture as a potential treatment of multiple fractures.
Assuntos
Acrilamidas/química , Fraturas Ósseas/terapia , Fraturas Múltiplas/terapia , Hidrogéis/química , Metacrilatos/química , Polietilenoglicóis/química , Polímeros/química , Animais , Adesão Celular , Sobrevivência Celular , Cerâmica/química , Durapatita/química , Fibroblastos/metabolismo , Consolidação da Fratura , Vidro , Luz , Camundongos , NF-kappa B/química , Células NIH 3T3 , Fotoquímica , Polímeros/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse Mecânico , Resistência à TraçãoRESUMO
The development of convenient synthetic methods and improved materials for the production of high load-capacity and biocompatible drug delivery systems is a challenging task with important implications in health sciences. In this work, acrylamide/2-hydroxyethylmethacrylate and N-isopropylacrylamide/2-hydroxyethylmethacrylate hydrogels were synthesized by photopolymerization using energy-efficient green-LEDs. A functionalized silsesquioxane was used as both crosslinker and co-initiator for the photopolymerization. The hybrid organic-inorganic nature of the silsesquioxane improved the resulting hydrogels' properties increasing their swelling capacity and biocompatibility. Additionally, the mild conditions used during the photopolymerization allowed the synthesis of hydrogels in the presence of antibiotics yielding high load-capacity materials in which the drug preserves its molecular structure and antimicrobial activity (as confirmed by HPLC and microbiological assays). The materials were characterized by FTIR, DSC and SEM. Additionally, the kinetics of gels´ swelling and drug release were studied under physiological conditions (pHâ¯7.4 and 37⯰C). The results demonstrate how hydrogel composition affects the antibiotics-release kinetics. The final drug release percentage increased with increasing molar fraction of acrylamide or N-isopropylacrylamide and in most cases exceeded 85%. Finally, the antibacterial effect of loaded gels was characterized using a number of assays against Gram negative and Gram positive bacteria. The observed antibacterial effect correlated well with swelling and drug release results. Furthermore, gels are not toxic for isolated erythrocytes as demonstrated by haemolytic tests. Overall, our results indicate that the produced hydrogels are promising materials to develop controlled drug-delivery devices such as capsules, dermatological patches and others.
Assuntos
Antibacterianos/farmacologia , Hidrogéis/química , Polimerização , Acrilamidas/química , Ampicilina/farmacologia , Preparações de Ação Retardada/farmacologia , Liberação Controlada de Fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Gentamicinas/farmacologia , Hemólise/efeitos dos fármacos , Humanos , Hidrogéis/síntese química , Cinética , Metacrilatos/química , Testes de Sensibilidade Microbiana , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus/efeitos dos fármacos , ÁguaRESUMO
OBJECTIVE: Synthesize and characterize a methacrylamide monomer for adhesive system and evaluate the physicochemical properties of the adhesive resin. METHODS: The liquid methacrylamide monomer N,N',Nâ³-(nitrilotris(ethane-2,1-dyil)tris(2-methylacrylamide) (TMA) was prepared by reaction of methacrylic anhydride and tris(2-aminoethyl)amine with 60% yields. The TMA structure was analyzed by 1H NMR, 13C NMR, ATR-FTIR and UHPLC-QTOF-MS. Experimental adhesive resin containing bisphenol-A glycidyl methacrylate (BISGMA), 2-hydroxyethylacrylamide (HEAA), 2-hydroxyethylmethacrylate (HEMA) and TMA were formulated. Polymerization kinetics of neat TMA and experimental adhesive resin (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%, TMA50%/HEMA50%, BisGMA/HEAA/TMA and BisGMA/HEMA) were evaluated using Differential Scanning Calorimetry. Physiochemical properties for BisGMA/HEAA/TMA and BisGMA/HEMA adhesives were evaluated by cytotoxicity, ultimate tensile strength (UTS), softening in solvent (ΔKHN), contact angle (θ), microtensile bond strength (µTBS) and failure analysis. A primer was also formulated with H2O/HEAA/AMPS (2-acrylamido-2-methylpropane sulfonic acid) and the pH value was verified and compared to commercial primer. RESULTS: Adhesive resin with only HEAA and TMA (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%) showed lower conversion and polymerization rate after 40s of light activation. Conversion up to 60% was found for BisGMA/HEAA/TMA and BisGMA/HEMA adhesive resin without significant difference between groups, p>0.05. Cytotoxicity, UTS, µTBS, ΔKHN and θ showed no statistical difference, p>0.05, between BisGMA/HEAA/TMA and BisGMA/HEMA adhesive resin. SIGNIFICANCE: In this study, the proposed synthetic route resulted in a tris(methacrylamide). A new primer composed without acrylates or methacrylates was formulated for 3-step etch-and-rinse adhesive system without the presence of HEMA monomer. Physicochemical properties and cell viability of BisGMA/HEAA/TMA adhesive resin represents an alternative adhesive resin without HEMA monomer.