Comparative analyses of response surface methodology and artificial neural networks on incorporating tetracaine into liposomes

This study evaluated the incorporation of tetracaine into liposomes by RSM (Response Surface Methodology) and ANN (Artificial Neural Networks) based models. RCCD (rotational central composite design) and ANN were performed to optimize the sonication conditions of particles containing 100 % lipid. Laser light scattering was used to perform measure hydrodynamic radius and size distribution of vesicles. The liposomal formulations were analyzed by incorporating the drug into the hydrophilic phase or the lipophilic phase. RCCD and ANN were conducted, having the lipid/cholesterol ratio and concentration of tetracaine as variables investigated and, the encapsulation efficiency and mean diameter of the vesicles as response variables. The optimum sonication condition set at a power of 16 kHz and 3 minutes, resulting in sizes smaller than 800 nm. Maximum encapsulation efficiency (39.7 %) was obtained in the hydrophilic phase to a tetracaine concentration of 8.37 mg/mL and 79.5:20.5% lipid/cholesterol ratio. Liposomes were stable for about 30 days (at 4 ºC), and the drug encapsulation efficiency was higher in the hydrophilic phase. The experimental results of RCCD-RSM and ANN techniques show ANN obtained more refined prediction errors that RCCD-RSM technique, therefore, ANN can be considered as an efficient mathematical method to characterize the incorporation of tetracaine into liposomes.

Comparison of acid and enzymatic hydrolysis of pectin, as inexpensive source to cell growth of Cupriavidus necator.

Abstract: The present work investigated what the appropriate methods of hydrolysis of pectin for reducing compounds (RCs) production, employed as a substrate for cell growth of Cupriavidus necator. This microorganism has great importance industrial, because besides potential single cell protein (SCP), is the most studied microorganism for production of polyhydroxybutyrate (PHB), and both processes require high cell concentration with inexpensive substrates For this, it was compared to acid and enzymatic hydrolysis procedures, through rotational central composite experimental design, using pectin concentration (1.0%). It was analyzed as a variable response for both experimental design, the RCs' production. The best conditions of each procedure were used in study kinetics of RCs' production and as a substrate for cell growth of C. necator. The results indicated that the enzymatic hydrolysis method was the most efficient, with a 93.0% yield of RCs, while the yield for acid hydrolysis was 60.0%. The optimum conditions for enzymatic hydrolysis were an enzyme concentration of 10.01 UI/g (International Unit of enzyme per gram of pectin) and an agitation speed of 230.3 rpm. C. necator showed satisfactory growth in the media containing pectin hydrolysates, with specific growth rates (µMax) similar to those reported for other substrates.

Orange and Passion Fruit Wastes Characterization, Substrate Hydrolysis and Cell Growth of Cupriavidus necator, as Proposal to Converting of Residues in High Value Added Product.

Brazil is the world's largest producer of orange and passion fruit, which are destined mainly for industrialization, generating grand volumes of wastes. The solid portion of these residues is a rich source of pectin - composed mainly of galacturonic acid and neutral sugars, which through the hydrolysis process can be used in biological conversion processes, as the production of polyhydroxyalkanoates (PHAs). This way, we characterized these wastes, followed by the extraction and hydrolysis of pectin for employ as a substrate for the cell growth of Cupriavidus necator. The results confirmed the large portion of pectin (almost 40 g.100g-1) and soluble sugars, present in these wastes. The hydrolyzed extract showed as a good source of carbon for the cell growth of C. necator with YX/S 0.56 and 0.44, µMax 0.27 and 0.21 for orange and passion fruit wastes respectively, similar to other carbon sources. This way, the extraction and hydrolysis of orange and passion fruit wastes for the cellular growth of C. necator, can be a good alternative to converting of residues in high value added product.

Effect of edible coatings based on alginate/pectin on quality preservation of minimally processed 'Espada' mangoes.

The aims of the study were to develop and apply alginate and pectin-based edible coatings on minimally processed mango (Mangifera indica L.) variety 'Espada'. A full experimental design was performed using alginate, pectin and glycerol concentrations as independent variables and total soluble solids as response variable. Minimally processed mango was immersed in each film forming solution, calcium chloride and glycerol solutions pretreated with 1% (w/v) solution of ascorbic acid, dried at 25 ± 2 °C for 24 h and then refrigerated at 8 ± 1 °C for 14 d. Based on the results of the experimental design, the following formulations were evaluated: 2% (w/v) alginate/3% (w/v) pectin (with and without glycerol) and 3% (w/v) alginate/0.5% (w/v) pectin (with and without glycerol). Fruits coated with biopolymers had lower total soluble solids content and titratable acidity compared to the control group. The formulation containing 2% (w/v) alginate, 3% (w/v) pectin and 5.5% (w/v) glycerol showed the best performance for long-term refrigerated storage of minimally processed mango for a period of 16 d.

Microencapsulation of Lactobacillus casei by spray drying.

This study evaluates the use of spray drying to produce microparticles of Lactobacillus casei. Microorganism was cultivated in shaken flasks and the microencapsulation process was performed using a laboratory-scale spray dryer. A rotational central composite design was employed to optimise the drying conditions. High cell viability (1.1 × 10(10) CFU/g) was achieved using an inlet air temperature of 70 °C and 25% (w/v) of maltodextrin. Microparticles presented values of solubility, wettability, water activity, hygroscopicity and humidity corresponding to 97.03 ± 0.04%, 100% (in 1.16 min), 0.14 ± 0.0, 35.20 g H2O/100 g and 4.80 ± 0.43%, respectively. The microparticles were spherical with a smooth surface and thermally stable. Encapsulation improved the survival of L. casei during storage. After 60 days, the samples stored at -8 °C showed viable cell concentrations of 1.0 × 10(9) CFU/g.

Production of concentrates of bacterial bio-insecticide Bacillus thuringiensis var. israelensis by flocculation/sedimentation.

Flocculation/sedimentation of Bacillus thuringiensis var. israelensis (Bti) using flocculating agents has been studied. Batch cell production was performed in an agitated tank, and the flocculation assays were carried out in jar tests. Flocculent suspensions were characterized based on diameter of flocs and density. The best results were obtained with CaCl(2).2H(2)O, FeCl(3).6H(2)O, Al(2)(SO(4))(3) and tannin, with optimal flocculation concentrations of 2500, 2500, 3500 and 1000 mg l(-1), respectively. Thickening of the flocculent suspensions was investigated, leading to determination of the capacity curves of the settler. Bioassays against Aedes aegypti larvae demonstrated excellent results in insect control.

Concentration of Cupriavidus necator cells by flocculation and sedimentation.

Separation and cells concentration constitute important stages in most biotechnological processes. Particularly, use of flocculation/sedimentation can improve significantly the extraction of biopolymers accumulated by microorganisms and the biodegradation of xenobiotic compounds by cell sludge. In this work the use of tannin and aluminum sulphate (Al2(SO4)3) as flocculating agents for concentration of cells of Cupriavidus necator DSM 545 is evaluated. Cells were grown in broth nutrient medium in Erlenmeyer flasks, submitted to orbital agitation of 160 rpm at 30 °C for 21 h. The optimal concentrations of flocculating agents, as determined with a standard jar test method, were equal to 2,800 mg/L for tannin and 800 mg/L for Al2(SO4)3, allowing for recovery of 95% of the cells in both cases. Obtained flocs presented density and average diameter of 1.03 g/mL ± 0.01 g/mL and 158 µm ± 19 µm for tannin and of 1.05 g/mL ± 0.01 g/mL and 146 µm ± 14 µm for Al2(SO4)3, respectively. Batch settling tests were performed in order to determine the operational capacity of continuous settlers to be used for separation of the investigated flocculent suspensions. Finally, cultivation of cells using flocs as inoculum indicated that the cells remained viable after flocculation with usage of the optimum flocculating agent concentrations.