Publications by authors named "Silmar Baptista Nunes"

3 Publications

  • Page 1 of 1

Development of Bacterial Cellulose Biocomposites Combined with Starch and Collagen and Evaluation of Their Properties.

Materials (Basel) 2021 Jan 19;14(2). Epub 2021 Jan 19.

PPG GETEC, University Center SENAI CIMATEC, National Service of Industrial Learning, SENAI CIMATEC, Salvador 41650-010, Brazil.

One of the major benefits of biomedicine is the use of biocomposites as wound dressings to help improve the treatment of injuries. Therefore, the main objective of this study was to develop and characterize biocomposites based on bacterial cellulose (BC) with different concentrations of collagen and starch and characterize their thermal, morphological, mechanical, physical, and barrier properties. In total, nine samples were produced with fixed amounts of glycerol and BC and variations in the amount of collagen and starch. The water activity (0.400-0.480), water solubility (12.94-69.7%), moisture (10.75-20.60%), thickness (0.04-0.11 mm), water vapor permeability (5.59-14.06 × 10 g·mm/m·h·Pa), grammage (8.91-39.58 g·cm), opacity (8.37-36.67 Abs 600 nm·mm), elongation (4.81-169.54%), and tensile strength (0.99-16.32 MPa) were evaluated and defined. In addition, scanning electron microscopy showed that adding biopolymers in the cellulose matrix made the surface compact, which also influenced the visual appearance. Thus, the performance of the biocomposites was directly influenced by their composition. The performance of the different samples obtained resulted in them having different potentials for application considering the injury type. This provides a solution for the ineffectiveness of traditional dressings, which is one of the great problems of the biomedical sector.
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January 2021

Evaluation of Different Methods for Cultivating for Bacterial Cellulose and Montmorillonite Biocomposite Production: Wound-Dressing Applications.

Polymers (Basel) 2020 Jan 26;12(2). Epub 2020 Jan 26.

University Center SENAI CIMATEC, National Service of Industrial Learning, Laboratory of Pharmaceutical's Formulations, Health Institute of Technologies (ITS CIMATEC), Salvador 41650-010, Brazil.

Bacterial cellulose (BC) has received considerable attention due to its unique properties, including an ultrafine network structure with high purity, mechanical strength, inherent biodegradability, biocompatibility, high water-holding capacity and high crystallinity. These properties allow BC to be used in biomedical and industrial applications, such as medical product. This research investigated the production of BC by ATCC 23769 using different carbon sources (glucose, mannitol, sucrose and xylose) at two different concentrations (25 and 50 g∙L). The BC produced was used to develop a biocomposite with montmorillonite (MMT), a clay mineral that possesses interesting characteristics for enhancing BC physical-chemical properties, at 0.5, 1, 2 and 3% concentrations. The resulting biocomposites were characterized in terms of their physical and barrier properties, morphologies, water-uptake capacities, and thermal stabilities. Our results show that bacteria presented higher BC yields in media with higher glucose concentrations (50 g∙L) after a 14-day incubation period. Additionally, the incorporation of MMT significantly improved the mechanical and thermal properties of the BC membranes. The degradation temperature of the composites was extended, and a decrease in the water holding capacity (WHC) and an improvement in the water release rate (WRR) were noted. Determining a cost-effective medium for the production of BC and the characterization of the produced composites are extremely important for the biomedical applications of BC, such as in wound dressing materials.
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January 2020

Determination of Parameters for the Supercritical Extraction of Antioxidant Compounds from Green Propolis Using Carbon Dioxide and Ethanol as Co-Solvent.

PLoS One 2015 7;10(8):e0134489. Epub 2015 Aug 7.

Institute of Research and Technology, Tiradentes University, Aracaju, Sergipe, Brazil.

The aim of this study was to determine the best processing conditions to extract Brazilian green propolis using a supercritical extraction technology. For this purpose, the influence of different parameters was evaluated such as S/F (solvent mass in relation to solute mass), percentage of co-solvent (1 and 2% ethanol), temperature (40 and 50°C) and pressure (250, 350 and 400 bar) using supercritical carbon dioxide. The Global Yield Isotherms (GYIs) were obtained through the evaluation of the yield, and the chemical composition of the extracts was also obtained in relation to the total phenolic compounds, flavonoids, antioxidant activity and 3,5-diprenyl-4-hydroxicinnamic acid (Artepillin C) and acid 4-hydroxycinnamic (p-coumaric acid). The best results were identified at 50°C, 350 bar, 1% ethanol (co-solvent) and S/F of 110. These conditions, a content of 8.93±0.01 and 0.40±0.05 g/100 g of Artepillin C and p-coumaric acid, respectively, were identified indicating the efficiency of the extraction process. Despite of low yield of the process, the extracts obtained had high contents of relevant compounds, proving the viability of the process to obtain green propolis extracts with important biological applications due to the extracts composition.
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May 2016