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1.
Macromol Rapid Commun ; 41(5): e1900623, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32003518

RESUMO

ABC-type miktoarm star copolymers are synthesized using a single living radical polymerization (organocatalyzed living radical polymerization) via a "combinatorial" approach. The arm A is poly(butyl acrylate), the arm B is poly(methyl methacrylate), and the arm C encompasses hydrophobic and hydrophilic polyacrylates. A poly(butyl acrylate) with a vinyl chain end (macromonomer) is synthesized. A poly(methyl methacrylate) is subsequently connected to the reactive vinyl group to generate diblock copolymer. From the junction of the diblock copolymer, polymer C grew to yield star copolymers. An amphiphilic star copolymer is also synthesized, and its self-assembly structure is studied in an aqueous solution.


Assuntos
Polímeros/síntese química , Acrilatos/química , Resinas Acrílicas/química , Catálise , Interações Hidrofóbicas e Hidrofílicas , Polimerização , Polímeros/química , Polimetil Metacrilato/química
2.
Macromol Rapid Commun ; 41(5): e1900555, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32003532

RESUMO

Structured color in nature is controlled by nano- and micro-structured interfaces giving rise to a photonic bandgap. This study presents a biomimetic optical material based on polymeric inverse opals that respond to enzyme activity. Polymer colloids provide a template in which acryloyl-functionalized poly(ethylene glycol) is integrated; dissolution of the colloids leads to a hydrogel inverse opal that can be lithographically patterned using transfer printing. Incorporating enzyme substrates within the voids provides a material that responds to the presence of proteases through a shift in the optical properties.


Assuntos
Materiais Biocompatíveis/química , Hidrogéis/química , Nanoestruturas/química , Peptídeo Hidrolases/metabolismo , Polímeros/química , Materiais Biomiméticos/química , Coloides/química , Cor , Iridescência , Microscopia Eletrônica de Varredura , Nanoestruturas/ultraestrutura , Fótons , Polietilenoglicóis/química , Polimetil Metacrilato/química , Impressão
3.
Nat Commun ; 11(1): 879, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-32054851

RESUMO

Bio-hybrid light-emitting diodes (Bio-HLEDs) based on color down-converting filters with fluorescent proteins (FPs) have achieved moderate efficiencies (50 lm/W) and stabilities (300 h) due to both thermal- and photo-degradation. Here, we present a significant enhancement in efficiency (~130 lm/W) and stability (>150 days) using a zero-thermal-quenching bio-phosphor design. This is achieved shielding the FP surface with a hydrophilic polymer allowing their homogenous integration into the network of a light-guiding and hydrophobic host polymer. We rationalize how the control of the mechanical and optical features of this bio-phosphor is paramount towards highly stable and efficient Bio-HLEDs, regardless of the operation conditions. This is validated by the relationships between the stiffness of the FP-polymer phosphor and the maximum temperature reached under device operation as well as the transmittance of the filters and device efficiency.


Assuntos
Proteínas de Fluorescência Verde/genética , Luz , Organofosfatos/química , Polimetil Metacrilato/química , Semicondutores , Bioengenharia/métodos , Dicroísmo Circular , Cor , Desenho de Equipamento , Proteínas de Fluorescência Verde/química , Proteínas de Fluorescência Verde/isolamento & purificação , Mutação , Estrutura Secundária de Proteína/genética , Estrutura Terciária de Proteína/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Temperatura
4.
Macromol Rapid Commun ; 41(6): e1900582, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32037634

RESUMO

Annealing a supported polymer film in the melt state results in the growth of an irreversibly adsorbed layer, which has been shown to influence thin film properties such as diffusion and glass transition temperature. Adsorbed layer growth is attributed to many simultaneous interactions between individual monomer units and the substrate, stabilizing chains against desorption. In this study, adsorbed layers of polystyrene (PS), poly(methyl methacrylate) (PMMA), and their random copolymers are isolated by select solvents. While PS adsorbed layer thickness is largely unaffected by the choice of washing solvent, the PMMA adsorbed layer completely desorbs when washed with tetrahydrofuran and chloroform, as opposed to toluene. Scaling relationships between adsorbed layer thickness and degree of chain adsorption at the substrate enable the use of adsorbed layer thickness to probe specific polymer-substrate interactions. Composition-dependent desorption trends indicate non-preferential adsorption between styrene and methyl methacrylate repeat units at the substrate, despite differences in substrate interaction strength. This insight contributes to the developing mechanism for the adsorption of random copolymers during melt-state annealing, further extending the ability to predict processing-inducted changes to the properties of polymer thin films to heterogeneous systems.


Assuntos
Polímeros/química , Polimetil Metacrilato/química , Poliestirenos/química , Solventes/química , Adsorção , Clorofórmio/química , Furanos/química , Polímeros/síntese química , Solubilidade , Propriedades de Superfície , Temperatura , Tolueno/química
5.
Biomater Sci ; 8(5): 1455-1463, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-31960840

RESUMO

In this work, a biocompatible poly(N-hydroxyethyl acrylamide) (PHEAA) polymer with hydrogen bonding acceptors and donors in its side chains is prepared and mixed with tannic acid (TA) to form a supramolecular coacervate hydrogel (TAHE) due to multiple hydrogen-bonding interactions between TA and PHEAA. The coacervate TAHE hydrogel exhibits not only self-healing and antibacterial properties, but also strong adhesion to various substrates, with average adhesion strengths of 722 kPa, 522 kPa, 484 kPa, and 322 kPa to the substrates of iron, PMMA, ceramics, and glass, respectively. Notably, the hydrogel reformed by the rehydration of freeze-dried and ground TAHE hydrogel powder retains the initial adhesive performance and exhibits an excellent hemostatic ability. This novel adhesive hydrogel holds great potential as an adhesive hemostatic material for self-rescue in emergency situations.


Assuntos
Adesivos/química , Antibacterianos/química , Hemostáticos/química , Hidrogéis/química , Resinas Acrílicas/química , Adesivos/efeitos adversos , Adesivos/farmacologia , Animais , Antibacterianos/efeitos adversos , Antibacterianos/farmacologia , Linhagem Celular , Fibroblastos/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Hemostáticos/efeitos adversos , Hemostáticos/farmacologia , Hidrogéis/efeitos adversos , Hidrogéis/farmacologia , Ligação de Hidrogênio , Masculino , Camundongos , Polimetil Metacrilato/química , Ratos , Ratos Sprague-Dawley , Staphylococcus/efeitos dos fármacos , Taninos/química
6.
Macromol Rapid Commun ; 41(4): e1900613, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31958201

RESUMO

In the present work, poly(methyl methacrylate) (PMMA) is successfully grafted onto poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) side chains via directly activated CF bonds using Cu(0)/2,2'-bipyridine as catalyst. The reaction mechanism and the initiating sites can be confirmed by the structure of the graft copolymer. The graft copolymerization exhibits first-order kinetics, and reaction conditions can affect the chemical composition of the graft copolymer, including reaction time, reaction temperature, solvents, the amount of catalyst, and monomer. The introduction of rigid PMMA side chains onto P(VDF-TrFE) can effectively tune the displacement-electric field hysteresis behaviors of P(VDF-TrFE) from normal ferroelectric to anti-ferroelectric, even linear-like dielectric, under high electric field, resulting in dramatically reduced energy loss while maintaining the discharged energy density. This work may provide an effective strategy to introduce functional groups into P(VDF-TrFE) copolymer via activation of CF bonds.


Assuntos
Polimetil Metacrilato/química , Polivinil/química , Catálise , Cinética , Polimerização
7.
J Appl Oral Sci ; 28: e20190039, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939520

RESUMO

OBJECTIVE: This study aimed to evaluate the physical properties and antifungal activities of polymethyl methacrylate (PMMA) acrylic resins after the incorporation of chlorhexidine diacetate salt (CDA). METHODOLOGY: First, acrylic resin specimens were fabricated with Vipi Cor® and DuraLay® resins with and without the incorporation of 0.5%, 1.0% or 2.0% CDA. The residual monomer and CDA release were measured at intervals ranging from 2 hours to 28 days using ultraviolet spectrometry combined with high-performance liquid chromatography. The antifungal activity against C. albicans was evaluated with the agar diffusion method. Fourier transform infrared spectroscopy was used to analyze the degree of resin conversion. Finally, the water sorption values of the resins were also measured. RESULTS: The incorporated CDA concentration significantly changed the rate of CDA release (p<0.0001); however, the brand of the material appeared to have no significant influence on drug release. Subsequently, the inhibition zones were compared between the tested groups and within the same brand, and only the comparisons between the CDA 2% and CDA 1% groups and between the CDA 1% and CDA 0.5% groups failed to yield significant differences. Regarding the degrees of conversion, the differences were not significant and were lower only in the CDA 2% groups. Water sorption was significantly increased at the 1.0% and 2.0% concentrations. CONCLUSIONS: We concluded that the incorporation of CDA into PMMA-based resins enabled the inhibition of C. albicans growth rate, did not alter the degrees of conversion of the tested resins and did not change the release of residual monomers.


Assuntos
Antifúngicos/química , Clorexidina/análogos & derivados , Polimetil Metacrilato/química , Resinas Acrílicas/química , Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Clorexidina/química , Clorexidina/farmacologia , Cromatografia Líquida de Alta Pressão , Teste de Materiais , Polimetil Metacrilato/farmacologia , Valores de Referência , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , Água/química
8.
Mater Sci Eng C Mater Biol Appl ; 108: 110460, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923975

RESUMO

Myelosuppression, gastrointestinal toxicity and hypersensitivities always accompany chemotherapy of osteosarcoma (OS). In addition, the intricate karyotype of OS, the lack of targeted antitumor drugs and the bone microenvironment that provides a protective alcove for tumor cells reduce the therapeutic efficacy of chemotherapy. Here, we developed a multifunctional bone cement loaded with Fe3O4 nanoparticles and the antitumor drug doxorubicin (DOX/Fe3O4@PMMA) for synergistic MH ablation and chemotherapy of OS. The localized intratumorally administered DOX/Fe3O4@PMMA can change from liquid into solid at the tumor site via a polyreaction. The designed multifunctional bone cement was constructed with Fe3O4 nanoparticles, PMMA, and an antitumor drug approved by the U.S. Food and Drug administration (FDA). The injectability, magnetic hyperthermia (MH) performance, controlled drug release profile, and synergistic therapeutic effect of DOX/Fe3O4@PMMA in vitro were investigated in detail. Furthermore, the designed DOX/Fe3O4@PMMA controlled the release of DOX, enhanced the apoptosis of OS tissue, and inhibited the proliferation of tumor cells, demonstrating synergistic MH ablation and chemotherapy of OS in vivo. The biosafety of DOX/Fe3O4@PMMA was also evaluated in detail. This strategy significantly reduced surgical time, avoided operative wounds and prevented patient pain, showing a great clinical translational potential for OS treatment.


Assuntos
Cimentos para Ossos , Neoplasias Ósseas/terapia , Hipertermia Induzida , Nanopartículas de Magnetita , Osteossarcoma/terapia , Animais , Cimentos para Ossos/química , Cimentos para Ossos/farmacologia , Neoplasias Ósseas/metabolismo , Neoplasias Ósseas/patologia , Linhagem Celular Tumoral , Doxorrubicina/química , Doxorrubicina/farmacologia , Humanos , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/uso terapêutico , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Osteossarcoma/metabolismo , Osteossarcoma/patologia , Polimetil Metacrilato/química , Polimetil Metacrilato/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto
9.
PLoS One ; 15(1): e0228076, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31978197

RESUMO

Electrical recording permits direct readout of neural activity but offers limited ability to correlate it to the network topography. On the other hand, optical imaging reveals the architecture of neural circuits, but relies on bulky optics and fluorescent reporters whose signals are attenuated by the brain tissue. Here we introduce implantable devices to record brain activities based on the field effect, which can be further extended with capability of label-free electrophysiological mapping. Such devices reply on light-addressable potentiometric sensors (LAPS) coupled to polymer fibers with integrated electrodes and optical waveguide bundles. The LAPS utilizes the field effect to convert electrophysiological activity into regional carrier redistribution, and the neural activity is read out in a spatially resolved manner as a photocurrent induced by a modulated light beam. Spatially resolved photocurrent recordings were achieved by illuminating different pixels within the fiber bundles. These devices were applied to record local field potentials in the mouse hippocampus. In conjunction with the raster-scanning via the single modulated beam, this technology may enable fast label-free imaging of neural activity in deep brain regions.


Assuntos
Encéfalo/fisiologia , Polímeros/química , Animais , Eletrodos , Fenômenos Eletrofisiológicos , Concentração de Íons de Hidrogênio , Luz , Masculino , Camundongos Endogâmicos C57BL , Cimento de Policarboxilato/química , Polimetil Metacrilato/química , Temperatura
10.
Colloids Surf B Biointerfaces ; 188: 110763, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31896518

RESUMO

For the first time, an electrophoretic deposition (EPD) method has been developed for the deposition of polymethylmethacrylate (PMMA) and PMMA-alumina films for biomedical implant applications. The proposed biomimetic approach was based on the use of a bile salt, sodium cholate (NaCh), which served as a multifunctional solubilizing, charging, dispersing and film-forming agent. Investigations revealed PMMA-Ch- and PMMA-alumina interactions, which facilitated the deposition of PMMA and PMMA-alumina films. This approach allows for the use of a non-toxic water-ethanol solvent for PMMA. The proposed deposition strategy can also be used for co-deposition of PMMA with other functional materials. The PMMA and composite films were tested for biomedical implant applications. The PMMA-alumina films showed statistically improved metabolic results compared to both the bare stainless steel substrate and pure PMMA films. Alkaline phosphatase (ALP) activity affirmed the bioactivity and osteoconductive potential of PMMA and composite films. PMMA-alumina films showed greater ALP activity than both the PMMA-coated and uncoated stainless steel.


Assuntos
Pesquisa Biomédica , Osteossarcoma/metabolismo , Polimetil Metacrilato/metabolismo , Fosfatase Alcalina/metabolismo , Óxido de Alumínio/química , Óxido de Alumínio/metabolismo , Eletroforese , Humanos , Osteossarcoma/patologia , Tamanho da Partícula , Polimetil Metacrilato/química , Propriedades de Superfície
11.
Colloids Surf B Biointerfaces ; 188: 110765, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31955016

RESUMO

Clinically relevant microorganisms threaten patient's health often through biofilm formation on polymeric medical devices and implants. Poly (methyl methacrylate) is a commonly used polymer in medical implants and dental devices. In this study, biofilm characteristics of model microorganisms, Pseudomonas aeruginosa, Staphylococcus epidermidis and Candida albicans, were investigated at molecular level on 2-dimensional (2D) and 3-dimensional (3D) PMMA substrates to understand the influence of surface structures on biofilm formation and also to demonstrate the discrimination of microorganisms according to their metabolic activities by utilizing surface-enhanced Raman scattering (SERS). It was found that the fibrous 3D structure enhanced the assembly of microorganisms and enriched the biofilm structure while smooth polymeric surface decreased the biofilm formation rate and variety of biofilm content. Among the studied microorganisms, Pseudomonas aeruginosa and Candida albicans had a higher tendency to form biofilm on both 2D and 3D PMMA substrates. Although Staphlylococcus epidermidis showed slow adaption on PMMA surfaces, the 3D porous surfaces increased its biofilm formation rate significantly compared to 2D surface.


Assuntos
Candida albicans/fisiologia , Polimetil Metacrilato/química , Pseudomonas aeruginosa/fisiologia , Staphylococcus epidermidis/fisiologia , Biofilmes , Tamanho da Partícula , Análise Espectral Raman , Propriedades de Superfície
12.
J Chromatogr A ; 1609: 460440, 2020 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-31416625

RESUMO

At the borderline between size exclusion chromatography (SEC) and interaction chromatography (IC) there is a special mobile phase composition and temperature at which polymer chains become "chromatographically invisible". This point is termed as "chromatographic critical point" and chromatographic separations performed using these conditions are called "liquid chromatography at critical conditions" (LCCC). LCCC is a powerful technique in the analysis of functional polymers and block copolymers. At these so-called critical conditions molar mass discrimination of any specific homopolymer is suppressed rendering elution of whole range of molar mass at same elution volume. These conditions allow enhanced separation with regard to non-critical segment either in exclusion or interaction regime of the polymer chromatography. This article is intended to critically discuss different parameters that can be maneuvered to improve separation and in turn characterization of non-critical segment of block copolymers at LCCC. Different experimental parameters evaluated in this study include pore size of the column, mobile phase composition, temperature and gradients. These parameters can be adeptly adjusted to improve separation of non-critical segment while keeping the other segment close to critical conditions. Current study demonstrates that pore diameter and mobile phase are the only practical variable that can be used for improvement of characterization of non-critical block in the block copolymer while non-critical block is in exclusion regime. On the other hand, pore diameter of the column, temperature, solvent composition and gradients are important parameters that can be skillfully tuned for improvement of separation of non-critical block while non-critical block elutes in interaction regime. The above-mentioned variations are evaluated for di-block as well as tri-block copolymers of A-B-A and B-A-B type. Moreover, LCCC-IC is especially important for analysis of poloxamers.


Assuntos
Cromatografia Líquida/métodos , Poloxâmero/análise , Temperatura , Cromatografia em Gel , Polietilenoglicóis/química , Polimetil Metacrilato/química , Porosidade , Solventes/química
13.
J Environ Sci Health B ; 55(4): 301-309, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31814523

RESUMO

In this study, the preparation and characterization of haloxyfop-R-methyl herbicide loaded in poly(methylmethacrylate) (PMMA) nano-capsules by emulsion polymerization and its release behavior were investigated. The chemical characterizations of PMMA/haloxyfop-R-methyl nano-capsules were confirmed by FT-IR spectroscopy method, and the surface morphology was studied by field emission scanning electron microscopy and transmission electron microscopy. Also, the herbicide loading and encapsulation efficiency were analyzed for the herbicide-loaded nano-capsules. The release rate of PMMA/haloxyfop-R-methyl nano-capsules was determined by UV-visible spectroscopy. The thermal properties and thermal stability of nano-capsules were explored by the thermal gravimetric analysis method. The diameter of the nano-capsules was in the range of 100-300 nm. Increasing the amount of herbicide in nano-formulations significantly affected the surface of the nano-capsules and reduced their surface smoothness. Triton-X100 was identified as the best surfactant for the preparation of nano-capsules, and the sample containing the lowest herbicide content showed the best performance in terms of encapsulation and loading efficiency. This sample showed a steady-state release rate during the six days.


Assuntos
Herbicidas/farmacocinética , Nanoestruturas/química , Polimetil Metacrilato/química , Piridinas/química , Piridinas/farmacocinética , Cápsulas , Preparações de Ação Retardada , Emulsões/química , Herbicidas/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Octoxinol/química , Polimerização , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
14.
Talanta ; 206: 120235, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514880

RESUMO

In the present work, an ion-pair based dispersive liquid-liquid microextraction was performed on a centrifugal chip for the first time. The entire DLLME procedure, including flow direction, desperation, and sedimentation of the extracting phase, can be fulfilled automatically on a solitary chip. The chip was made of Poly(methyl methacrylate) (PMMA) and was of two units for two parallel extractions, each consisting of three chambers (for the sample solution, extracting solvents, and sedimentation). As the chip rotated, fluids flowed within the chip, and the dispersion, mixing, extraction, and sedimentation of the final phase were performed on the chip by simply adjusting the spin speed. Determination of two histamine H2 receptor antagonist drugs, cimetidine and ranitidine, as the model analytes from the urine samples was done using the developed on-chip ion-pair based DLLME method followed by an HPLC-UV. The effective parameters on the extraction efficiency of the model analytes were investigated and optimized using the one variable at a time method. Under optimized conditions, the calibration curve was linear in the range of 15-2000 µg L-1 with a coefficient of determination (R2) more than 0.9987. The relative standard deviations (RSD %) for extraction and determination of the analytes were less than 3.7% based on five replicated measurements. LODs less than 10.0 µg L-1 and preconcentration factors higher than 39-fold were obtained for both of the model analytes. The proposed chip enjoys the advantages of both the DLLME method and miniaturization on a centrifugal chip.


Assuntos
Cimetidina/urina , Antagonistas dos Receptores Histamínicos H2/urina , Dispositivos Lab-On-A-Chip , Microextração em Fase Líquida/métodos , Ranitidina/urina , Cromatografia Líquida de Alta Pressão , Humanos , Microextração em Fase Líquida/instrumentação , Polimetil Metacrilato/química
15.
Mater Sci Eng C Mater Biol Appl ; 106: 110292, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753402

RESUMO

The objective of this systematic review is to evaluate the effect of the incorporation of zirconia (ZrO2) particles on the mechanical properties of PMMA (polymethyl methacrylate), and to establish which characteristics of this material yield the best results aiming their biomedical applicability. This study was carried out in accordance with the Items of Preferred Reports for Systematic Reviews and Meta-Analyzes (PRISMA) and is registered in PROSPERO under registration number: CRD42018095801. The searches were carried out in the PubMed, MEDLINE, Scopus and Cochrane Library databases for articles published up until April 2018. After the different stages of the article selection process, eight articles were selected for qualitative and quantitative analysis. All were in vitro studies, totaling 536 evaluated samples. The concentrations of zirconia ranged from 0.5% to 20% and the particle sizes were between 15 nm and 10 µm. The incorporation of zirconia particles did not increase the flexural strength of PMMA in only one study. While the concentration of zirconia influences PMMA, the type of acrylic resin, size, and silanization of zirconia particles did not influence the results. Thus, the addition of zirconia particles showed a positive effect on PMMA enhancing their use in the medical and dental field, especially when certain anatomical areas requires higher strength of the materials, providing longevity for the rehabilitation.


Assuntos
Polimetil Metacrilato/química , Zircônio/química , Bases de Dados Factuais , Resistência à Flexão , Tamanho da Partícula
16.
Int J Mol Sci ; 20(24)2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31817604

RESUMO

Hybrid and antimicrobial nanoparticles (NPs) of poly (methyl methacrylate) (PMMA) in the presence of poly (diallyl dimethyl ammonium) chloride (PDDA) were previously obtained by emulsion polymerization in absence of surfactant with low conversion. In the presence of amphiphiles such as cetyl trimethyl ammonium bromide (CTAB), dioctadecyl dimethyl ammonium bromide (DODAB) or soybean lecithin, we found that conversion increased substantially. In this work, the effect of the amphiphiles on the NPs core-shell structure and on the antimicrobial activity of the NPs was evaluated. NPs dispersions casted on silicon wafers, glass coverslips or polystyrene substrates were also used to obtain antimicrobial coatings. Methods for characterizing the dispersions and coatings were based on scanning electron microscopy, dynamic light scattering, determination of thickness, rugosity, and wettability for the coatings and determination of colony-forming unities (log CFU/mL) of microbia after 1 h interaction with the coatings or dispersions. The amphiphiles used during PMMA/PDDA/amphiphile NPs synthesis reduced the thickness of the NPs PDDA shell surrounding each particle. The antimicrobial activity of the dispersions and coatings were due to PDDA-the amphiphiles were either washed out by dialysis or remained in the PMMA polymeric core of the NPs. The most active NPs and coatings were those of PMMA/PDDA/CTAB-the corresponding coatings showed the highest rugosity and total surface area to interact with the microbes. The dispersions and coatings obtained by casting of the NPs dispersions onto silicon wafers were hydrophilic and exhibited microbicidal activity against Escherichia coli, Staphylococcus aureus, and Candida albicans. In addition, a major effect of reduction in particle size revealed the suitability of nanometric and cationic NPs (sizes below 100 nm) represented by PMMA/PDDA/CTAB NPs to yield maximal microbicidal activity from films and dispersions against all microbia tested. The reduction of cell viability by coatings and dispersions amounted to 6-8 logs from [PDDA] ≥ minimal microbicidal concentration.


Assuntos
Compostos Alílicos/química , Antibacterianos/química , Anti-Infecciosos/química , Lipídeos/química , Nanopartículas/química , Polímeros/química , Polimetil Metacrilato/química , Compostos de Amônio Quaternário/química , Tensoativos/química , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana , Staphylococcus aureus/efeitos dos fármacos
17.
ACS Appl Mater Interfaces ; 11(49): 46350-46360, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31722179

RESUMO

Miniaturized systems, such as integrated microarray and microfluidic devices, are constantly being developed to satisfy the growing demand for sensitive and high-throughput biochemical screening platforms. Owing to its recyclability, and robust mechanical and optical properties, poly(methyl methacrylate) (PMMA) has become the most sought after material for the large-scale fabrication of these platforms. However, the chemical inertness of PMMA entails the use of complex chemical surface treatments for covalent immobilization of proteins. In addition to being hazardous and incompatible for large-scale operations, conventional biofunctionalization strategies pose high risks of compromising the biomolecular conformations, as well as the stability of PMMA. By exploiting radio frequency (RF) air plasma and standard 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry in tandem, we demonstrate a simple yet scalable PMMA functionalization strategy for covalent immobilization (chemisorption) of proteins, such as green fluorescent protein (GFP), while preserving the structural integrities of the proteins and PMMA. The surface density of chemisorbed GFP is shown to be highly dependent on the air plasma energy, initial GFP concentration, and buffer pH, where a maximum GFP surface density of 4 × 10-7 mol/m2 is obtained, when chemisorbed on EDC-NHS-activated PMMA exposed to 27 kJ of air plasma, at pH 7.4. Furthermore, antibody-binding studies validate the preserved biofunctionality of the chemisorbed GFP molecules. Finally, the coupled air plasma and EDC-NHS PMMA biofunctionalization strategy is used to fabricate microfluidic antibody assay devices to detect clinically significant concentrations of Chlamydia trachomatis specific antibodies. By coupling our scalable and tailored air plasma-enhanced PMMA biofunctionalization strategy with microfluidics, we elucidate the potential of fabricating sensitive, reproducible, and sustainable high-throughput protein screening systems, without the need for harsh chemicals and complex instrumentation.


Assuntos
Ensaios de Triagem em Larga Escala/métodos , Proteínas Imobilizadas/química , Dispositivos Lab-On-A-Chip , Polimetil Metacrilato/química , Ar , Proteínas de Fluorescência Verde/química , Análise em Microsséries/métodos , Gases em Plasma/química , Ondas de Rádio , Propriedades de Superfície
18.
J Appl Biomater Funct Mater ; 17(4): 2280800019872594, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31718388

RESUMO

Treatment of bone defects caused by trauma or disease is a major burden on human healthcare systems. Although autologous bone grafts are considered as the gold standard, they are limited in availability and are associated with post-operative complications. Minimally invasive alternatives using injectable bone cements are currently used in certain clinical procedures, such as vertebroplasty and balloon kyphoplasty. Nevertheless, given the high incidence of fractures and pathologies that result in bone voids, there is an unmet need for injectable materials with desired properties for minimally invasive procedures. This paper provides an overview of the most common injectable bone cement materials for clinical use. The emphasis has been placed on calcium phosphate cements and acrylic bone cements, while enabling the readers to compare the opportunities and challenges for these two classes of bone cements. This paper also briefly reviews antibiotic-loaded bone cements used in bone repair and implant fixation, including their efficacy and cost for healthcare systems. A summary of the current challenges and recommendations for future directions has been brought in the concluding section of this paper.


Assuntos
Transplante Ósseo , Fosfatos de Cálcio , Teste de Materiais , Polimetil Metacrilato , Cimentos para Ossos/química , Cimentos para Ossos/uso terapêutico , Fosfatos de Cálcio/química , Fosfatos de Cálcio/uso terapêutico , Humanos , Cifoplastia , Polimetil Metacrilato/química , Polimetil Metacrilato/uso terapêutico
19.
J Appl Oral Sci ; 27: e20180779, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31691740

RESUMO

Candida albicans is the main causative pathogen of denture stomatitis, which affects many complete denture patients. OBJECTIVE: To evaluate the effect of different concentrations of nanodiamonds (NDs) added to polymethyl methacrylate (PMMA) denture base material on Candida albicans adhesion as well as on surface roughness and contact angle. METHODOLOGY: Acrylic resin specimens sized 10×10×3 mm3 were prepared and divided into four groups (n=30) according to ND concentration (0%, 0.5%, 1%, 1.5% by wt). Surface roughness was measured with a profilometer, and the contact angle with a goniometer. The effect of NDs on Candida albicans adhesion was evaluated using two methods: 1) slide count and 2) direct culture test. Analysis of variance (ANOVA) and Tukey's post hoc test were used in the statistical analyses. RESULTS: Addition of NDs decreased the Candida albicans count significantly more than in the control group (p<0.05), with a lowest of 1% NDs. Addition of NDs also significantly decreased the surface roughness (p<0.05), but the contact angle remained the same. Incorporation of NDs into the PMMA denture base material effectively reduced Candida albicans adhesion and decreased surface roughness. CONCLUSION: PMMA/NDs composites could be valuable in the prevention of denture stomatitis, which is considered one of the most common clinical problems among removable denture wearers.


Assuntos
Resinas Acrílicas/química , Candida albicans/efeitos dos fármacos , Bases de Dentadura/microbiologia , Nanodiamantes/química , Nanodiamantes/microbiologia , Polimetil Metacrilato/química , Análise de Variância , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Estomatite sob Prótese/microbiologia , Estomatite sob Prótese/prevenção & controle , Propriedades de Superfície
20.
J Appl Oral Sci ; 27: e20180663, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31596368

RESUMO

OBJECTIVE: To investigate the use of polymethyl methacrylate (PMMA) electrospun fiber mats containing different amounts of polyethylene oxide (PEO) as a doxycycline delivery system and to test antibacterial activity against an oral pathogen. METHODOLOGY: PMMA powders or PEO (mol wt 200 Kd) (10,20,30% w/w/) were dissolved in N, N-dimethylformamide (DMF) to obtain a final polymer concentration of 15% in DMF (w/v). 2% Doxycycline monohydrate was added to the solutions and submitted to vortex mixing. The solution was transferred to a plastic syringe and fit into a nanofiber electrospinning unit. The parameters applied were: voltage at 17.2 kV; distance of 20 cm between the needle tip and the collector plate; target speed at 2 m/min; and transverse speed at 1cm/min. Syringe pump speed was 0.15 mm/min. The drug release analysis was performed by removing aliquots of the drug-containing solution (in PBS) at specific periods. Doxycycline release was quantified using RP-HPLC. Fiber mats from all groups had their antibacterial action tested against S. mutans based on inhibition halos formed around the specimens. The experiments were performed in triplicate. Gravimetric analysis at specific periods was performed to determine any polymer loss. Morphological characterization of the electrospun fibers was completed under an optical microscope followed by SEM analysis. RESULTS: The addition of PEO to the PMMA fibers did not affect the appearance and diameter of fibers. However, increasing the %PEO caused higher doxycycline release in the first 24 h. Fibers containing 30% PEO showed statistically significant higher release when compared with the other groups. Doxycycline released from the fibers containing 20% or 30% of PEO showed effective against S. mutans. CONCLUSION: The incorporation of PEO at 20% and 30% into PMMA fiber mat resulted in effective drug release systems, with detected antibacterial activity against S. mutans.


Assuntos
Antibacterianos/farmacocinética , Doxiciclina/farmacocinética , Nanofibras/química , Polietilenoglicóis/farmacocinética , Polimetil Metacrilato/farmacocinética , Análise de Variância , Antibacterianos/química , Cromatografia Líquida de Alta Pressão/métodos , Doxiciclina/química , Imersão , Microscopia Eletrônica de Varredura , Peso Molecular , Polietilenoglicóis/química , Polimetil Metacrilato/química , Reprodutibilidade dos Testes , Streptococcus mutans/efeitos dos fármacos , Fatores de Tempo , Água/química
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