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1.
Pharm Dev Technol ; 25(1): 100-106, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31583937

RESUMO

Roller compaction is a popular dry granulation method that has been associated with loss of tabletability. In this study, the effect of roller compaction on a model brittle elastic material, paracetamol, was examined. Roller compaction of paracetamol was carried out at three roll force to examine the effects of roll force on the tablet compaction properties. Paracetamol granules consisting of small fragmented crystals were created through the process of roller compaction. A compaction simulator was used to produce tablets from a sieved fraction of roller compacted paracetamol and non-roller compacted paracetamol. Despite the higher elastic energy to plastic energy ratio observed with tablets produced from roller compacted granules of higher forces, the table tensile strength obtained was higher with a lower capping coefficient. At the same time, tablet elastic recovery was found to be lower for tablets produced using roller compacted paracetamol granules. Prefragmentation during roller compaction process helped to reduce the energy required for fragmentation during tablet compaction, increasing the energy available for bond formation. Roller compaction of brittle elastic materials may be a viable option for improving tablet tensile strength and reducing tablet capping.


Assuntos
Acetaminofen/química , Composição de Medicamentos/métodos , Excipientes/química , Tamanho da Partícula , Comprimidos/química , Resistência à Tração/efeitos dos fármacos
2.
Medicina (Kaunas) ; 55(12)2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31810222

RESUMO

Background and Objectives: The aim of this systematic review was to examine the effect of 2% chlorhexidine following acid etching on the microtensile bond strength of resin restorations for different follow-up times. Materials and Methods: A thorough search of PubMed, Scopus, and Embase databases were conducted. In vitro experimental studies or in vivo studies published up to December 2018 with an experimental group treated with a 2% chlorhexidine solution following acid etching and a control group were included, wherein the final restoration used a resin composite in both the groups. Results: Twenty-one articles were identified for qualitative analysis and 18 for meta-analysis. The difference in the means of microtensile bond strength between the two groups was calculated for the different follow-up times. The differences were significant for 6 months (4.30 MPa; 95% CI 2.72-5.89), 12 months (8.41 MPa; 95% CI 4.93-11.88), and 2-5 years including aged and thermocycling samples (9.08 MPa; 95% CI 5.36-12.81). There were no significant differences for the type of adhesive used. A meta-regression model showed a significant effect of time on the microtensile bond strength. Conclusions: The application of a 2% chlorhexidine solution after acid etching increased the microtensile bond strength significantly for follow-up times of 6 months or more. The adhesive type had no influence.


Assuntos
Clorexidina/farmacologia , Resinas Compostas , Cimentos Dentários/farmacologia , Resistência à Tração/efeitos dos fármacos , Condicionamento Ácido do Dente , Humanos
3.
Braz Oral Res ; 33: e111, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31800863

RESUMO

The aim of the present study was to evaluate the microtensile bond strength and the microleakage of a bulk-fill composite resin compared with a conventional incremental composite resin, in permanent molars and under cariogenic challenge using a Streptococcus mutans model. Permanent human third molars (n = 60) with an occlusal cavity of 5×3×2 mm were randomly allocated into four subgroups of restorative treatments: conventional composite resin with (n = 15) and without (n = 15) cariogenic challenge (Z350-E and Z350-C experimental and control groups, respectively), and bulk-fill composite resin with (n = 15) and without (n = 15) cariogenic challenge (Bulk Fill-E and Bulk Fill-C, respectively). Ten specimens from each subgroup were submitted to microtensile strength, and 5, to microleakage. The cariogenic challenge was conducted using the Streptococcus mutans strain (ATCC) for 7 days. The stickers obtained (1 × 1 × 2 mm) were submitted to a microtensile strength test, followed by classification of the fracture mode. Microleakage was performed using a scoring system. The data were analyzed by Kruskal-Wallis and Mann-Whitney tests (p < 0.05). Filtek Z350 XT resin presented higher microtensile bond strength than Bulk Fill resin without (19.02 ± 4.90 and 8.76 ± 3.94MPa, respectively; p < 0.001) and with cariogenic challenge (22.69 ± 7.86 and 13.31 ± 3.38MPa, respectively; p < 0.02). Z350-C and Bulk Fill-C resins presented a higher prevalence of mixed fractures (23 and 14%, respectively) in the specimens submitted to cariogenic challenge than those of the control groups, whereas microleakage was similar (p = 0.85). The conventional composite resin had higher microtensile bond strength than the bulk-fill resin, but both resin types had similar adhesion quality and microfiltration scores.


Assuntos
Biofilmes/efeitos dos fármacos , Resinas Compostas/química , Colagem Dentária/métodos , Streptococcus mutans/efeitos dos fármacos , Adesividade , Cárie Dentária , Esmalte Dentário/efeitos dos fármacos , Infiltração Dentária , Restauração Dentária Permanente/métodos , Humanos , Teste de Materiais , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Propriedades de Superfície , Resistência à Tração/efeitos dos fármacos , Fatores de Tempo
4.
Mater Sci Eng C Mater Biol Appl ; 104: 110002, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499949

RESUMO

Although PVA-chitosan composite hydrogel has excellent biocompatibility and antibacterial ability, its poor mechanical strength limits its application for wound dressings. Furthermore, PVA-chitosan composite hydrogel cannot satisfy the requirements of wound dressing as an environmental conditioner to accelerate wound healing. In this work, a novel lignin-chitosan-PVA composite hydrogel was prepared as wound dressing. The introduction of lignin effectively improved the mechanical strength (tensile stress is up to 46.87 MPa), protein adsorption capacity, and wound environmental regulation ability of the hydrogel. In a murine wound model, the lignin-chitosan-PVA composite hydrogel significantly accelerated wound healing. The developed hydrogel provides new opportunities for highly efficient skin wound care and management.


Assuntos
Quitosana/química , Hidrogéis/química , Hidrogéis/farmacologia , Lignina/química , Álcool de Polivinil/química , Cicatrização/efeitos dos fármacos , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Bandagens , Feminino , Camundongos , Pele/efeitos dos fármacos , Resistência à Tração/efeitos dos fármacos
5.
Mater Sci Eng C Mater Biol Appl ; 104: 109956, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499971

RESUMO

In this work, both cellulose nanocrystals (CNC) and reduced graphene oxide (rGO) were reinforced into poly-lactic acid (PLA) to enhance the stiffness, strength and thermal stability of the pure polymer i.e. PLA. To enhance the uniform dispersion of CNC (which is a major concern with PLA) and rGO in the hydrophobic polymer matrix, CNC's surface was first modified using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation method followed by surface grafting of TEMPO-oxidized CNC (TOCNC) performed with polyethylene glycol (PEG). The PEG-grafting on crystalline region of cellulose nanofibrils was achieved through ionic bonds by applying ion-exchange method (simple and easy method). The obtained PEG-grafted-TOCNC indicated uniform dispersion at the nanoelement level in non-polar (organic) compound i.e. chloroform. Further, the PEG-grafted-TOCNC/chloroform with different blend ratios, PLA/chloroform and rGO/chloroform solution were mixed together and solvent casted onto a petri-dish to obtain PLA/PEG-TOCNC/rGO nanocomposite film. The tensile strength and thermal stability were remarkably improved for the film containing highest wt% of modified CNC. In addition to this, the film showed reduced water vapor barrier properties and antioxidant activity which enables it to be used as a packaging films. Moreover, the film displayed negligible toxicity and cytocompatibility to fibroblast cells C3H10T1/2. These attractive properties of PLA/PEG-TOCNC/rGO nanocomposite film render the application of film as a scaffold in tissue engineering field and in packaging application.


Assuntos
Celulose Oxidada/química , Óxidos N-Cíclicos/química , Grafite/química , Nanocompostos/química , Nanopartículas/química , Poliésteres/química , Polietilenoglicóis/química , Polímeros/química , Solventes/química , Vapor , Temperatura , Resistência à Tração/efeitos dos fármacos , Engenharia Tecidual/métodos
6.
Mater Sci Eng C Mater Biol Appl ; 104: 109946, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499982

RESUMO

The reinforcement of PMMA bone cements using carbon based nanomaterials has demonstrated to be a potential solution to their poor mechanical properties. The achievement of an optimal dispersion of the nanoparticles within the polymeric matrix is a crucial but not easy stage in the production of high-quality reinforced materials. In this work, a useful route for the graphene (G) functionalisation, via silanisation with (3-methacryloxypropyl) trimethoxy silane (MPS), has been developed, providing a remarkable enhancement in dispersibility and mechanical properties. With the purpose to define the critical graphene surface oxidation parameters for an optimal silanisation, different routes were thoroughly analysed using infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results showed that the silanisation significantly improved the G dispersibility: whereas the pristine G dispersion fell down within the first 24 h, the silanised G showed an adequate stability after 5 days. Additionally, this improved dispersibility produced a notable increase in the mechanical properties of the G-reinforced bone cements: in comparison with the pristine G, the compression and bending strength of silanised G increased by 12% and by 13.7% respectively and the fracture toughness by 28%. These results provide very useful information on the relevance that the characteristics of the superficial oxidation of graphene have on the effectiveness of the silanisation process, besides an interesting functionalisation procedure for advanced dispersion and reinforcement of G-PMMA bone cements.


Assuntos
Cimentos para Ossos/química , Grafite/química , Polimetil Metacrilato/química , Silanos/química , Teste de Materiais/métodos , Estresse Mecânico , Propriedades de Superfície/efeitos dos fármacos , Resistência à Tração/efeitos dos fármacos
7.
Wounds ; 31(7): 166-172, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31184994

RESUMO

OBJECTIVE: The purpose of this study is to introduce a wound closure testing method that reproduces a pulling or stretching force, leading to more accurate supporting data for clinicians to select the proper product when closing a low- or high-tension incision in conjunction with deep dermal sutures. MATERIALS AND METHODS: Incisions were made in the center of 70 prepared porcine skin samples. They were cleaned with isopropanol and wiped dry before applying the adhesive, as per each respective manufacturer's instructions. A tensile tester was used to pull the incisions apart and record each wound closure maximum disruption force. A paired t test assuming unequal variances was performed on the data. RESULTS: This new wound closure test method was determined to be more advantageous when compared with previous methods in terms of approximation incision, approximation of clinical scenario, approximation directional force experienced by incision, number of steps, sample preparation time, and equipment needed. One specific 2-octyl cyanoacrylate topical skin adhesive product was revealed to have statistically significantly higher wound closure strength than most of the investigated adhesives. That topical skin adhesive exhibited a higher mean strength than all other cyanoacrylate tissue adhesives tested in this study. CONCLUSIONS: The study indicates this wound closure test has the potential to be an ideal testing method for predicting the strength of a wound-sealing adhesive subjected to a pulling or stretching force. The topical skin adhesive that demonstrated the highest mean strength of the 7 cyanoacrylate adhesive products tested potentially could be the optimal wound closure device for low- or high-tension incisions in conjunction with deep dermal sutures.


Assuntos
Cianoacrilatos/uso terapêutico , Resistência à Tração/efeitos dos fármacos , Adesivos Teciduais/uso terapêutico , Técnicas de Fechamento de Ferimentos/instrumentação , Cicatrização/fisiologia , Administração Tópica , Animais , Modelos Animais , Suínos , Cicatrização/efeitos dos fármacos
8.
Biomed Res Int ; 2019: 8961409, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31011582

RESUMO

Polycaprolactone (PCL) has attracted great attention for bone regeneration attributed to its cost-efficiency, high toughness, and good processability. However, the relatively low elastic modulus, hydrophobic nature, and insufficient bioactivity of pure PCL limited its wider application for bone regeneration. In the present study, the effects of the addition of boron containing bioactive glass (B-BG) materials on the mechanical properties and biological performance of PCL polymer were investigated with different B-BG contents (0, 10, 20, 30, and 40 wt.%), in order to evaluate the potential applications of B-BG/PCL composites for bone regeneration. The results showed that the B-BG/PCL composites possess better tensile strength, human neutral pH value, and fast degradation as compared to pure PCL polymers. Moreover, the incorporation of B-BG could enhance proliferation, osteogenic differentiation, and angiogenic factor expression for rat bone marrow stromal cells (rBMSCs) as compared to pure PCL polymers. Importantly, the B-BG also promoted the angiogenic differentiation for human umbilical vein endothelial cells (HUVECs). These enhanced effects had a concentration dependence of B-BG content, while 30 wt.% B-BG/PCL composites achieved the greatest stimulatory effect. Therefore the 30 wt.% B-BG/PCL composites have potential applications in bone reconstruction fields.


Assuntos
Indutores da Angiogênese/farmacologia , Materiais Biocompatíveis/farmacologia , Regeneração Óssea/efeitos dos fármacos , Boro/farmacologia , Vidro/química , Osteogênese/efeitos dos fármacos , Poliésteres/química , Animais , Materiais Biocompatíveis/química , Linhagem Celular , Módulo de Elasticidade/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana , Humanos , Teste de Materiais/métodos , Células-Tronco Mesenquimais/efeitos dos fármacos , Polímeros/química , Ratos , Ratos Sprague-Dawley , Resistência à Tração/efeitos dos fármacos
9.
Cell Tissue Bank ; 20(2): 287-295, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31020508

RESUMO

Structural bone allografts are often sterilized with γ-irradiation to decrease infection risk, which unfortunately degrades the bone collagen connectivity, making the bone weak and brittle. In previous studies, we successfully protected the quasi-static mechanical properties of human cortical bone by pre-treating with ribose, prior to irradiation. This study focused on the quasi-static and fatigue tensile properties of ribose treated irradiated sterilized bone allografts. Seventy-five samples were cut from the mid-shaft diaphysis of human femurs into standardized dog-bone shape geometries for quasi-static and fatigue tensile testing. Specimens were prepared in sets of three adjacent specimens. Each set was made of a normal (N), irradiated (I) and ribose pre-treated + irradiation (R) group. The R group was incubated in a 1.2 M ribose solution before γ-irradiation. The quasi-static tensile and decalcified tests were conducted to failure under displacement control. The fatigue samples were tested under cyclic loading (10 Hz, peak stress of 45MP, minimum-to-maximum stress ratio of 0.1) until failure or reaching 10 million cycles. Ribose pre-treatment significantly improved significantly the mechanical properties of irradiation sterilized human bone in the quasi-static tensile and decalcified tests. The fatigue life of the irradiated group was impaired by 99% in comparison to the normal control. Surprisingly, the R-group has significantly superior properties over the I-group and N-group (p < 0.01, p < 0.05) (> 100%). This study shows that incubating human cortical bone in a ribose solution prior to irradiation can indeed improve the fatigue life of irradiation-sterilized cortical bone allografts.


Assuntos
Fêmur/efeitos dos fármacos , Fêmur/efeitos da radiação , Raios gama/efeitos adversos , Ribose/farmacologia , Resistência à Tração/efeitos dos fármacos , Resistência à Tração/efeitos da radiação , Adolescente , Adulto , Idoso , Aloenxertos/efeitos da radiação , Diáfises/efeitos dos fármacos , Diáfises/efeitos da radiação , Feminino , Fêmur/transplante , Humanos , Masculino , Pessoa de Meia-Idade , Estresse Mecânico , Adulto Jovem
10.
J Biosci Bioeng ; 128(3): 323-331, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31010728

RESUMO

The biodegradable polylactic acid (PLA) materials, environmentally friendly alternatives to petroleum-derived plastics, and fermentative production of optically pure lactic acid from cheap raw materials have aroused interest among researchers in the recent years due to its high potential for packaging applications. In this study, we have experimented for the lactic acid production using Lactobacillus delbrueckii MTCC 911 with Prosopis juliflora as a substrate for fermentation. As a result, 38.23 g/L of lactic acid was produced. Modified ring-opening polymerization with direct polycondensation method was followed to convert lactic acid into polylactic acid, and membrane prepared with 0.25 mm thickness having PLA/chitosan 60/40 composition shows better results with a tensile strength of 17.809 MPa and an elongation at break of 300.11%. The oxygen transmission rate results show low permeability of 1614.21 (cm3/(m2·day·atm)). Compatible PLA/chitosan membrane so produced by solvent casting shows good thermal stablity and less permeability to oxygen and increased mechanical properties. This was evident from the instrumental analysis of Fourier-transform infrared spectroscopy, thermogravimetry/derivative thermogravimetry, scanning electron microscope, and high-performance liquid chromatography results.


Assuntos
Quitosana/farmacologia , Embalagem de Alimentos/métodos , Poliésteres/metabolismo , Prosopis/metabolismo , Quitosana/química , Cromatografia Líquida de Alta Pressão , Ácido Láctico/química , Microscopia Eletrônica de Varredura , Poliésteres/química , Polimerização/efeitos dos fármacos , Espectroscopia de Infravermelho com Transformada de Fourier , Resistência à Tração/efeitos dos fármacos , Termogravimetria
11.
J Appl Microbiol ; 126(6): 1772-1784, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30920096

RESUMO

AIMS: To evaluate whether decoloured cell-free supernatant of Lysobacter enzymogenes C3 can decrease paper bioreceptivity to fungal attack. METHODS AND RESULTS: To prepare colourless C3 supernatant, single-factor design and uniform design were applied. The optimum conditions with high decolouration degree and low antifungal activity loss were achieved as follows: carbon granule content 1·6% (M/V), temperature 27°C, decolouring time 1·2 h and pH 8·0. An agar plate bioassay was used to assess the antifungal activity of the decoloured supernatant against the fungal isolates obtained from contaminated books, and strong suppression was observed. Small-sacle laboratory test was further introduced, in which common book papers were artificially inoculated with the fungal isolates, and then sprayed uniformly with decoloured supernatant or water. The results showed that, after treatment, the paper showed a significantly low extent of fungal colonization and high tensile strength, and maintained the same colour before and after treatment. CONCLUSION: These results suggest that the decoloured C3 supernatant inhibits fungal growth on types of paper commonly used in books. SIGNIFICANCE AND IMPACT OF THE STUDY: Decoloured C3 supernatant could be used as a preventive agent to protect books and other paper-based items against fungal growth.


Assuntos
Antifúngicos/química , Livros , Fungos/crescimento & desenvolvimento , Lysobacter/química , Papel , Antifúngicos/farmacologia , Meios de Cultivo Condicionados/química , Meios de Cultivo Condicionados/farmacologia , Fungos/efeitos dos fármacos , Resistência à Tração/efeitos dos fármacos
12.
Carbohydr Polym ; 212: 59-66, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30832881

RESUMO

A novel bilayer film of chitosan and konjac glucomannan were prepared by the two-step casting technique. Blend films were also prepared to investigate the interactions between the two polymers in the interfacial region of the bilayer structure. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis showed that, unlike in the blends, the physicochemical properties of each biopolymer were preserved in the bilayer film. Differential scanning calorimetry and thermogravimetric analysis also indicated a good thermostability and miscibility for both polymers, probably due to strong hydrogen bonds between their polymer chains. Biological, mechanical and water vapor transmission tests showed a high biocompatibility, low cytotoxicity, and suitable mechanical and barrier properties of the bilayer films for wound dressing applications.


Assuntos
Bandagens , Quitosana/síntese química , Mananas/síntese química , Plantas , Candida albicans/efeitos dos fármacos , Candida albicans/fisiologia , Quitosana/farmacologia , Cromatografia em Gel/métodos , Avaliação Pré-Clínica de Medicamentos/métodos , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia , Mananas/farmacologia , Resistência à Tração/efeitos dos fármacos , Resistência à Tração/fisiologia , Difração de Raios X/métodos
13.
Int J Pharm ; 559: 156-172, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30682449

RESUMO

Roller compaction is the main technique employed in dry granulation. Ribbon sticking and splitting are among the major factors that can hinder the use of this process for some formulations. Ribbon splitting can occur either transversally (through the ribbon thickness) or longitudinally (through the ribbon width). It was observed that transverse splitting is commonly associated with sticking of the split ribbons to the rollers and results in an inferior performance of the process. Longitudinal splitting is associated with an across-width distribution of the ribbon density so that there may an adverse effect on the mechanical strength and dissolution properties of the tablets formed from the milled granules. The aim of the current work was to elucidate the mechanisms of splitting by an experimental study involving single component powders with a range of yield strengths, including those that are commonly used as excipients. Both smooth and knurled rollers were employed without and with lubrication by applying magnesium stearate to the rollers. The minimum gap was fixed and the maximum roll stress was varied. The observed trends for the smooth rollers were rationalised in terms of a splitting index, which is a measure of the residual stresses driving crack growth relative to the tensile strength of the ribbons. There was a lower limit at which splitting was observed but the occurrence of transverse splitting decreased and that for longitudinal splitting increased with increasing values of the index, which was accompanied by an increase in mixed transverse-longitudinal splitting. Transverse splitting was always associated with sticking to the rollers and was prevented by external lubrication. The main difference with the knurled rollers was that in some cases transverse splitting occurred without sticking to the rollers. A detailed discussion of the mechanisms involved is presented.


Assuntos
Comprimidos/química , Celulose/química , Química Farmacêutica/métodos , Composição de Medicamentos/métodos , Excipientes/química , Lubrificação/métodos , Tamanho da Partícula , Porosidade/efeitos dos fármacos , Pós/química , Pressão , Solubilidade/efeitos dos fármacos , Ácidos Esteáricos/química , Tecnologia Farmacêutica/métodos , Resistência à Tração/efeitos dos fármacos
14.
J Orthop Surg Res ; 14(1): 32, 2019 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-30683125

RESUMO

BACKGROUND: Polyetheretherketone (PEEK) exhibits stable chemical properties, excellent biocompatibility, and rational mechanical properties that are similar to those of human cortical bone, but the lack of bioactivity impedes its clinical application. METHODS: In this study, hydroxyapatite (HA) was incorporated into PEEK to fabricate HA/PEEK biocomposite using a compounding and injection-molding technique. The tensile properties of the prepared HA/PEEK composites (HA content from 0 to 40 wt%) were tested to choose an optimal HA content. To evaluate the bioactivity of the composite, the cell attachment, proliferation, spreading and alkaline phosphatase (ALP) activity of MC3T3-E1 cells, and apatite formation after immersion in simulated body fluid (SBF), and osseointegration in a rabbit cranial defect model were investigated. The results were compared to those from ultra-high molecular weight polyethylene (UHMWPE) and pure PEEK. RESULTS: By evaluating the tensile properties and elastic moduli of PEEK composite samples/PEEK composites with different HA contents, the 30 wt% HA/PEEK composite was chosen for use in the subsequent tests. The results of the cell tests demonstrated that PEEK composite samples/PEEK composite exhibited better cell attachment, proliferation, spreading, and higher ALP activity than those of UHMWPE and pure PEEK. Apatite islands formed on the HA/PEEK composite after immersion in SBF for 7 days and grew continuously with longer time periods. Animal tests indicated that bone contact and new bone formation around the HA/PEEK composite were more obvious than those around UHMWPE and pure PEEK. CONCLUSIONS: The HA/PEEK biocomposite created by a compounding and injection-molding technique exhibited enhanced osteogenesis and could be used as a candidate of orthopedic implants.


Assuntos
Materiais Biocompatíveis/administração & dosagem , Durapatita/administração & dosagem , Cetonas/administração & dosagem , Osso Parietal/efeitos dos fármacos , Polietilenoglicóis/administração & dosagem , Resistência à Tração/efeitos dos fármacos , Animais , Linhagem Celular , Avaliação Pré-Clínica de Medicamentos/métodos , Feminino , Osso Parietal/lesões , Osso Parietal/cirurgia , Coelhos , Resistência à Tração/fisiologia
15.
Int J Pharm ; 559: 37-47, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30660749

RESUMO

The effect of thermal binders on the physicochemical properties of gabapentin, a thermally labile drug, in granules prepared using twin-screw melt granulation was investigated in this study. Hydroxypropyl cellulose (HPC), a thermoplastic high molecular-weight binder, was compared against conventional low molecular-weight semi-crystalline thermal binders PEG 8000 and Compritol. Both the chemical degradation and polymorph form change of gabapentin were analyzed. The effects of particle size and molecular weight of HPC on the properties of granules were also studied. To overcome the high melt viscosity of HPC, higher barrel temperatures and higher specific mechanical energy were required to attain suitable granules. As a result, higher levels of gabapentin degradant were observed in HPC-based formulations. However, gabapentin form change was not observed in all formulations. Smaller particle size and lower molecular weight of HPC led to faster granule growth. The tabletability of granules was insensitive to the variations in particle size and molecular weight of HPC. Gabapentin crystal size reduction, HPC size reduction, and HPC enrichment on granule surface were observed for HPC-based granules.


Assuntos
Gabapentina/química , Comprimidos/química , Parafusos Ósseos , Celulose/análogos & derivados , Celulose/química , Química Farmacêutica/métodos , Composição de Medicamentos/métodos , Excipientes/química , Peso Molecular , Tamanho da Partícula , Pós/química , Tecnologia Farmacêutica/métodos , Resistência à Tração/efeitos dos fármacos , Viscosidade/efeitos dos fármacos
16.
Int J Pharm ; 559: 130-137, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30599228

RESUMO

Cracking patterns in four kinds of granules, based on the common pharmaceutical excipient microcrystalline cellulose (MCC) and subject to compressive load, were examined. The initial pore structure and the location of initial failure under uniaxial compression were assessed using X-ray micro-computed tomography, whereas contact force development and onset of cracking under more complex compressive load were examined using a triaxial testing apparatus. Smoothed particle hydrodynamics (SPH) simulations were employed for numerical analysis of the stress distributions prior to cracking. For granules subject to uniaxial compression, initial cracking always occurred along the meridian and the precise location of the crack depended on the pore structure. Likewise, for granules subject to triaxial compression, the fracture plane of the primary crack was generally parallel to the dominant loading direction. The occurrence of cracking was highly dependent on the triaxiality ratio, i.e. the ratio between the punch displacements in the secondary and dominant loading directions. Compressive stresses in the lateral directions, induced by triaxial compression, prevented crack opening and fragmentation of the granule, something that could be verified by simulations. These results provide corroboration as well as further insights into previously observed differences between confined and unconfined compression of granular media.


Assuntos
Celulose/química , Força Compressiva/efeitos dos fármacos , Fenômenos Mecânicos/efeitos dos fármacos , Estresse Mecânico , Resistência à Tração/efeitos dos fármacos , Microtomografia por Raio-X/métodos
17.
Mar Drugs ; 17(1)2019 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-30621270

RESUMO

Nanofibrous structures mimicking the native extracellular matrix have attracted considerable attention for biomedical applications. The present study aims to design and produce drug-eluting core-shell fibrous scaffolds for wound healing and skin tissue engineering. Aloe vera extracts were encapsulated inside polymer fibers containing chitosan, polycaprolactone, and keratin using the co-axial electrospinning technique. Electron microscopic studies show that continuous and uniform fibers with an average diameter of 209 ± 47 nm were successfully fabricated. The fibers have a core-shell structure with a shell thickness of about 90 nm, as confirmed by transmission electron microscopy. By employing Fourier-transform infrared spectroscopy, the characteristic peaks of Aloe vera were detected, which indicate successful incorporation of this natural herb into the polymeric fibers. Tensile testing and hydrophilicity measurements indicated an ultimate strength of 5.3 MPa (elongation of 0.63%) and water contact angle of 89°. In-vitro biological assay revealed increased cellular growth and adhesion with the presence of Aloe vera without any cytotoxic effects. The prepared core-shell fibrous mats containing medical herbs have a great potential for wound healing applications.


Assuntos
Plantas Medicinais/química , Pele/efeitos dos fármacos , Tecidos Suporte/química , Cicatrização/efeitos dos fármacos , Aloe/química , Quitosana/química , Teste de Materiais/métodos , Microscopia Eletrônica de Varredura/métodos , Nanofibras/química , Poliésteres/química , Polímeros/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Resistência à Tração/efeitos dos fármacos , Engenharia Tecidual/métodos
18.
J Mech Behav Biomed Mater ; 90: 374-380, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30408756

RESUMO

OBJECTIVES: The aim of the study was to evaluate the effect of bioactive glass (45S5 and NbG) suspensions on bond strength (µTBS), hardness, modulus of elasticity, pH and antibacterial activity of the resin-dentin interfaces after 3 months. METHODS: Groups with different concentrations (5% and 20%) of two types of glass (45S5 and NbG), and a control group (distilled water) were studied. Twenty-five extracted human third molars were etched with phosphoric acid. The data from µTBS, hardness and modulus of elasticity data were submitted to two-way ANOVA (suspension vs. time) and Holm-Sidak tests (=0.05). The antimicrobial activity data were analyzed by the Kruskal-Wallis test (α = 5%). RESULTS: The interactions were significant among groups for µTBS (p = 0.033). Significant reductions in µTBS were observed after 3 months storage in PBS for the Control and 5% NbG Groups. Suspensions with 5% and 20% 45S5 glass and 20% NbG resulted in stable µTBS values and increased hardness after 3 months. Both 20% suspensions (45S5 and NbG) increased the elastic modulus. A significant greater reduction in bacterial growth was observed with the use of 20% 45S5. CONCLUSION: Rewetting dentin with the suspension of 20% 45S5 glass prevented the reduction in bond strength; increased hardness; modulus of elasticity of the resin-dentin interface, and demonstrated antibacterial activity against Streptococcus mutans.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Cerâmica/química , Cerâmica/farmacologia , Dentina/efeitos dos fármacos , Vidro/química , Resistência à Tração , Relação Dose-Resposta a Droga , Elasticidade/efeitos dos fármacos , Dureza/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Streptococcus mutans/efeitos dos fármacos , Resistência à Tração/efeitos dos fármacos
19.
J Pharm Pharmacol ; 71(3): 293-305, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30485903

RESUMO

OBJECTIVES: To investigate the effects of formulation composition on the physico-chemical and drug release properties of mucoadhesive buccal films prepared by melt extrusion technology, using a response surface methodology. METHODS: Salbutamol sulphate, an antiasthmatic drug was used for this study. Klucel hydroxypropylcellulose (HPC) EF (film-forming polymer), Benecel hydroxypropylmethylcellulose (HPMC) K-15M (drug release retardant) and polyethylene glycol (PEG) 4500 (plasticiser) were the three independent factors utilised for the study. The responses were fitted to a full quadratic model and P-values for each of the factors were used to determine their significance on the film characteristics. KEY FINDINGS: Films were successfully extruded using the corotating twin-screw extruder. The torque during extrusion was found to be significantly affected by all the three factors and no interaction between factors was observed. A significant interaction was observed between HPC and PEG 4500 for stiffness of films. For disintegration time and swelling index, a significant interaction was found between HPC and HPMC. The in vitro % drug release was directly correlated with HPMC content and not with other factors and varied from 69-89% at 4 h. CONCLUSIONS: The influence of extrusion process and formulation parameters on salbutamol sulphate films was elucidated, indicating the use of melt extrusion as a feasible method for film preparation.


Assuntos
Adesivos/administração & dosagem , Adesivos/química , Mucosa Bucal/efeitos dos fármacos , Administração Bucal , Albuterol/administração & dosagem , Albuterol/química , Antiasmáticos/administração & dosagem , Antiasmáticos/química , Celulose/análogos & derivados , Celulose/química , Química Farmacêutica/métodos , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos/efeitos dos fármacos , Temperatura Alta , Derivados da Hipromelose/química , Plastificantes/química , Polietilenoglicóis/química , Polímeros/química , Tecnologia Farmacêutica/métodos , Resistência à Tração/efeitos dos fármacos
20.
Medicine (Baltimore) ; 97(35): e12093, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30170430

RESUMO

To evaluate the effects of different etching concentrations of phosphoric acid on the microtensile bond strength of Adper Single Bond 2 to fluorotic teeth.Deidentified extracted teeth were collected, including 30 sound teeth, 30 teeth with mild fluorosis, 30 teeth with moderate fluorosis, and 30 teeth with severe fluorosis. The teeth in each group were randomly divided into 3 subgroups (n = 10) that were subjected to acid etching using 35%, 40%, or 45% phosphoric acid. Adper Single Bond 2 (3M, Saint Paul, MN) was used as the adhesive for bonding Z250 universal resin (3M) to the etched dental enamel. Microtensile testing was used to determine the bond strength. After the microtensile test, the fractured specimens were examined under scanning electron microscopy (SEM).Both dental fluorosis and concentrations of phosphoric acid significantly affected the microshear bond strength of Adper Single Bond 2 to dental enamel. The maximum bond strength was achieved by using 40% phosphoric acid. Failure analysis showed that most failures occurred at the bonding interface. The rates of failures at the bonding interface decreased as the degree of fluorosis increased and as the concentration of phosphoric acid increased from 35% to 45%.The bond strength of fluorosis tooth was lower than that of healthy tooth, the bond strength increased with the increasing concentration of phosphoric acid, but an excessively high acid concentration can conversely lead to an apparent decline in bond strength.


Assuntos
Esmalte Dentário/efeitos dos fármacos , Corrosão Dentária/métodos , Fluorose Dentária/tratamento farmacológico , Ácidos Fosfóricos/farmacologia , Cimentos Dentários , Humanos , Microscopia Eletrônica de Varredura , Resistência à Tração/efeitos dos fármacos
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