Loading of bacterial cellulose dressing with frutalin, a lectin from Artocarpus incisa L.

Bacterial cellulose (BC), produced by bacterial fermentation, is a high-purity material. BC can be oxidized (BCOXI), providing aldehyde groups for covalent bonds with drugs. Frutalin (FTL) is a lectin capable of modulating cell proliferation and remodeling, which accelerates wound healing. This study aimed to develop an FTL-incorporated dressing based on BC, and to evaluate its physicochemical properties and biological activity in vitro. An experimental design was employed to maximize FTL loading yield onto the BC and BCOXI, where independent variables were FTL concentration, temperature and immobilization time. BCOXI-FTL 1 (44.96 % ± 1.34) had the highest incorporation yield (IY) at the experimental conditions: 6 h, 5 °C, 20 µg mL-1. The second highest yield was BCOXI-FTL 6 (23.28 % ± 1.43) using 24 h, 5 °C, 100 µg mL-1. Similarly, the same reaction parameters provided higher immobilization yields for native bacterial cellulose: BC-FTL 6 (16.91 % ± 1.05) and BC-FTL 1 (21.71 % ± 1.57). Purified FTL displayed no cytotoxicity to fibroblast cells (<50 µg mL-1 concentration) during 24 h. Furthermore, BCOXI-FTL and BC-FTL were non-cytotoxic during 24 h and stimulated fibroblast migration. BCOXI-FTL demonstrated neutrophil activation in vitro similar to FTL. These promising results indicate that the bacterial cellulose matrices containing FTL at low concentrations, could be used as an innovative biomaterial for developing wound dressings.

Development of silanized bacterial cellulose aerogels for the incorporation of natural oils with healing properties: Copaiba (Copaifera officinalis), bourbon geranium (Pelargonium X ssp.) essential oils and buriti (Mauritia flexuosa) vegetable oil.

Bacterial cellulose (BC) represents a promising biomaterial, due to its unique and versatile properties. We report, herein, on purposely-designed structural modifications of BC that enhance its application as a wound dressing material. Chemical modification of the functional groups of BC was performed initially to introduce a hydrophobic/oleophilic character to its surface. Specifically, silanization was carried out in an aqueous medium using methyltrimethoxisilane (MTMS) as the silanizing agent, and aerogels were subsequently prepared by freeze-drying. The BC-MTMS aerogel obtained displayed a highly porous (99 %) and lightweight structure with an oil absorption capacity of up to 52 times its dry weight. The XRD pattern indicated that the characteristic crystallographic planes of the native BC were maintained after the silanization process. Thermal analysis showed that the thermal stability of the BC-MTMS aerogel increased, as compared to the pure BC aerogel (pBC). Moreover, the BC-MTMS aerogel was not cytotoxic to fibroblasts and keratinocytes. In the second step of the study, the incorporation of natural oils into the aerogel's matrix was found to endow antimicrobial and/or healing properties to BC-MTMS. Bourbon geranium (Pelargonium X ssp.) essential oil (GEO) was the only oil that exhibited antimicrobial activity against the tested microorganisms, whereas buriti (Mauritia flexuosa) vegetable oil (BVO) was non-cytotoxic to the cells. This study demonstrates that the characteristics of the BC structure can be modified, while preserving its intrinsic features, offering new possibilities for the development of BC-derived materials for specific applications in the biomedical field.

Effectiveness of a formulation based on Ocimum gratissimum essential oil and cashew gum as inhibitors of quality loss and melanosis in shrimp.

In this study, two nanoemulsions were formulated with essential oil (EO) of Ocimum gratissimum with (EON) or without (EOE) cashew gum (CG). Subsequently, inhibition of melanosis and preservation of the quality of shrimp stored for 16 days at 4 ± 0.5 °C were evaluated. A computational approach was performed to predict the system interactions. Dynamic light scattering (DLS) and atomic force microscopy (AFM) were used for nanoparticle analysis. Gas chromatography and flame ionization detector (GC-FID) determined the chemical composition of the EO constituents. Shrimps were evaluated according to melanosis's appearance, psychrotrophic bacteria's count, pH, total volatile basic nitrogen, and thiobarbituric acid reactive substances. EON exhibited a particle size three times smaller than EOE. The shrimp treated with EON showed a more pronounced sensory inhibition of melanosis, which was considered mild by the 16th day. Meanwhile, in the other groups, melanosis was moderate (EOE) or severe (untreated group). Both EON and EOE treatments exhibited inhibition of psychrotrophic bacteria and demonstrated the potential to prevent lipid oxidation, thus extending the shelf life compared to untreated fresh shrimp. EON with cashew gum, seems more promising due to its physicochemical characteristics and superior sensory performance in inhibiting melanosis during shrimp preservation.

Emulgel based on fish skin collagen-microalgae-silver increased neovascularization and re-epithelialization of full thickness burn in rats.

Deep skin burn represents a global morbidity and mortality problem, and the limitation of topical treatment agents has motivated research to development new formulations capable of preventing infections and accelerating healing. The aim of this work was to develop and characterize an emulgel based on collagen (COL) and gelatin (GEL) extracted from fish skin associated with Chlorella vulgaris extract (CE) and silver nitrate (AgNO3). COL and GEL were characterized by physicochemical and thermal analyses; and CE by electrophoresis and its antioxidant capacity. Three emulgels formulations were developed: COL (0.5%) + GEL (2.5%) (E1), COL+GEL+CE (1%) (E2), and COL+GEL+CE + AgNO3 (0.1%) (E3). All formulations were characterized by physicochemical, rheology assays, and preclinical analyses: cytotoxicity (in vitro) and healing potential using a burn model in rats. COL and GEL showed typical physicochemical characteristics, and CE presented 1.3 mg/mL of proteins and antioxidant activity of 76%. Emulgels presented a coherent physicochemical profile and pseudoplastic behavior. Preclinical analysis showed concentration-dependent cytotoxicity against fibroblast and keratinocytes. In addition, all emulgels induced similar percentages of wound contraction and complete wound closure in 28 days. The histopathological analysis showed higher scores for polymorphonuclear cells to E1 and greater neovascularization and re-epithelialization to E3. Then, E3 formulation has potential to improve burn healing, although its use in a clinical setting requires further studies.