A indústria têxtil busca recuperar a diminuição do ritmo dos negócios, notado principalmente em países desenvolvidos devido ao cenário da economia mundial, por meio da elaboração de têxteis com maior valor agregado. A microencapsulação é uma técnica versátil e flexível que apresenta diversas vantagens, como evitar que o princípio ativo reaja com outros compostos presentes no sistema e possibilitar a liberação controlada, que aumenta potencialmente a eficiência do produto. O principal objetivo deste trabalho foi desenvolver microcápsulas de quitosana e alginato com incorporação de Triclosan, que possui propriedades bactericida e fungicida, para aplicação em substratos têxteis para utilizações médicas. As microcápsulas foram produzidas a partir do método de emulsificação e reticulação, e caracterizadas por Termogravimetria (TG), Calorimetria Exploratória Diferencial (DSC), Espectroscopia no Infravermelho com Transformada de Fourier (FTIR), capacidade de absorção de água e perda de massa, Microscopia Eletrônica de Varredura (MEV), ensaio de atividade bactericida e liberação in vitro. Após caracterizadas, as microcápsulas foram impregnadas em tecidos 100% algodão com ligamentos tela e sarja. Estes foram submetidos a testes físicos e análise de resistência à lavagem. As microcápsulas produzidas apresentaram forma esférica e tiveram 80,78% de eficiência de encapsulação do fármaco. Os ensaios de liberação mostraram que o fármaco não foi liberado em 24h, entretanto, o material apresentou atividade bactericida contra a bactéria gram-positiva S. aureus, com halo de inibição de até 60 mm e também contra a bactéria gram-negativa E. coli, com halo de até 25 mm. Os resultados de resistência à lavagem avaliados por MEV mostraram que as microcápsulas não permenceram no substrato. Entretanto, o material apresentou atividade antibacteriana podendo ser interessante para aplicação em materiais têxteis descartáveis, como bandagens utilizadas na área médica / The textile industry seeks to recover the decrease of the pace of business, noted mainly in developed countries due to the scenario of the world economy, through the development of textiles with higher added value. The microencapsulation is a versatile and flexible technique that presents several advantages such as to avoid that the active ingredient react with other compounds present in the system, and allow controlled release that potentially increases the efficiency of the product. The main objective of this work was to develop microcapsules of chitosan and alginate with incorporation of triclosan, which has bactericidal and fungicide properties, for use in textile substrates for medical uses. The microcapsules were produced from the method of emulsification and crosslinking, and characterized by Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), Infrared Spectroscopy Fourier Transform (FTIR), water absorption capacity and mass loss, Scanning Electron Microscopy (SEM), bactericidal activity assay and in vitro release. After characterized, the microcapsules were impregnated in 100% cotton twill and taffeta woven. Physical tests and analysis of resistance to washing were carried out. The microcapsules produced presented spherical shape and had 80.78% of drug encapsulation efficiency. Release tests showed that the drug was not released in 24 hours, however, the material presented bactericidal activity against the gram-positive bacterium S. aureus, with inhibition halo up to 60 mm and also against the gram-negative bacterium E. coli, with halo of up to 25 mm. The results of washing resistance evaluated by SEM showed that the microcapsules did not remain in the substrate. However, the material showed antibacterial activity and may be interesting for application in disposable textiles, such as bandages used in the medical field

This thesis investigates the transport and sorting of capsules (elastic membranes enclosing a liquid core) using viscous flow in complex vessel geometries. Of particular interest is passive sorting by deformability using only the fluid-structure interaction between the capsule, the viscous fluid and the geometry of the vessel. Millimetric alginate-ovalbumin capsules in the regime of negligible fluid inertia are used in this work. In order to characterise the elastic properties of the capsules, a novel numerical finite element model of the compression of a thick-shelled capsule between parallel plates is implemented. The constitutive model of the capsule membranes was determined by comparison to experimental data: a Yeoh constitutive model with the ratio of constants $C_1 = 1$, $C_2 = 0$ and $C_3 = 10$ describes the capsules used. Three geometries are investigated in this work. (i) A T-Junction bifurcation. Capsule deformation in the T-Junction bifurcation is characterised by the maximal length of the capsule $L_{max}$ and depends on the ratio of viscous to elastic forces, the capillary number $Ca$. The maximal length, $L_{max}$, is especially sensitive at distinguishing soft capsules by their deformability. The sensitivity of $L_{max}$ to capsule compliance and the large deformations that can be achieved makes the T-junction a promising geometry in which to measure elastic properties of the capsules. The rate of relaxation of the capsules after the bifurcation is independent of their deformation. (ii) A half-cylinder obstacle in a channel followed by a sudden expansion. We show that the half-cylinder obstacle causes capsule trajectories to vary depending on deformability. Capsules with a factor of three difference in deformability can be separated. A practical feature of the system is its relative insensitivity to the initial lateral position of the capsules in the channel. However, while the results are reproducible across different capsules, the variations in final position amount to 10 \% at fixed parameters. As these experiments were conducted with the same capsule under identical flow conditions, this is likely to represent the best case scenario. (iii) We adapt the pinched flow fractionation (PFF) geometry to the sorting of capsules. We show that the standard PFF device cannot be used to sort capsules. However, a novel mode of operation, termed the ``T-Junction'' mode, shows great promise for the sorting of capsules. The PFF device in the T-Junction mode separates capsules with a factor of 1.5 difference in deformability. This is twice as sensitive as the half-cylinder device, although larger variability was observed in the PFF device.

Enteric pathogens form a large part of infectious diseases which contribute to a bulk of the healthcare costs. Enteric infections are usually contracted via the faecal-oral route or through contact with contaminated surfaces. Treatment by antibiotics is becoming increasingly ineffective due to the growing number of antibiotic resistant strains. Anti-microbial resistance poses a serious threat to the future of healthcare worldwide and necessitates the search for alternate forms of therapy. Bacteriophages (phages), are viruses which specifically infect and lyse bacteria. To introduce phages as a viable form of therapy, route of administration needs to be considered carefully. Model phages with broad host ranges are ideal for therapy however oral delivery to the lower gastro-intestinal (GI) poses several challenges. The acidic stomach environment can be detrimental to phages, rendering them inactive during passage. To overcome this challenge and improve the stability of phage during encapsulation and storage, this PhD research has been conducted. pH responsive polymers, Eudragit and alginate were used to develop composite microparticles which protected phage from acidic pH (pH 1-3). A novel method of acidifying oil was developed for crosslinking droplets in vitro to avoid the use of harsh solvent systems that can cause phage inactivation. Platform microfluidic technology was employed for phage encapsulation for the first time. Monodispersed droplets and particles were produced, offering fine-tuning of droplet diameter to tailor the release and pH protection of encapsulated phage. Process scale-up was attempted using membrane emulsification (ME) to produce larger volumes of encapsulated phage. In vitro and in-situ models investigated the efficacy of encapsulated phage-bacterial killing. Industrial scale method of spray drying, and electrospinning were also used to demonstrate the versatility of the formulation. Tableting dry powder phage, showed an effective method for producing solid dosage forms for therapy. Additionally, electrospun phage fibres also showed the potential use of pH responsive formulations in addressing wound infections. Improvement in encapsulated phage storage stability was observed with the addition of trehalose in the formulation. This research underpins the need for testing phage encapsulation for site-specific delivery and offers insight into the potential use of commercially available technologies.

Os alginatos de metais alcalinos (Li+, Na+ e K+), alcalino-terrosos (Mg2+, Ca2+, Sr2+ e Ba2+), de amônio, mono-, di- e trietanolamônio foram sintetizados por neutralização do ácido algínico com os respectivos hidróxidos, ou carbonatos, e com as aminas. Os sais foram caracterizados por análise elementar e espectroscopia na região do infravermelho, confirmando as sínteses. Após caracterização, os compostos foram submetidos à análise térmica (TG/DTG, DTA e DSC) para avaliar seu comportamento térmico e seus resíduos de decomposição, que foram caracterizados por IR e XRD. Os alginatos de amônio e etanolamônio se decompuseram com liberação de amônia ao final do experimento. Os alginatos de metais alcalinos foram convertidos nos seus respectivos carbonatos, enquanto os alginatos de metais alcalino-terrosos se decompuseram formando carbonatos, em seguida óxidos. Foi feita uma avaliação de procedimentos de secagem por estufa a vácuo a 40 ºC e liofilização; e o último método mostrou-se mais eficaz. A água residual, não-congelável, sai associada à decomposição do material e não foi possível definir exatamente seu teor. Um método de medir o grau de substituição nos sais das aminas foi desenvolvido com base em 13C ? NMR em fase sólida. / The alkaline (Li+, Na+ and K+), earth-alkaline (Mg2+, Ca2+, Sr2+ and Ba2+), ammonium, mono-, di- and triethanolammonium alginic acid salts were obtained from the neutralization reaction between alginic acid and the respective hydroxides or carbonates, and the amines, The salts were characterized by elemental analysis and infrared spectroscopy, confirming the synthesis. After the characterization, the compounds were submitted to thermal analysis (TG/DTG, DTA and DSC), in order to evaluate their thermal behavior. The thermal decomposition residues were characterized by IR and/or XRD. The NH4+ and ethanolammonium alginates decomposed via NH3 release without residue in the crucible at the end of the experiment. The alkaline alginates were converted to the respective carbonates, and the earth-alkaline decomposed with production of the carbonates followed by convertion to the oxides. An evaluation of drying procedures involving heating under vaccum up to 40°C and lyophilization were performed, pointing better results in the last case. The residual water, of the non-freezing type, was completely released only during the decomposition of the biopolymer, and it was not possible to define its exact content in the samples. An attempt to estimate the substitution degree in the ethanolammonium salts using 13C ? NMR data, in solid state, was also described.

Injectable hydrogels are important for use in tissue engineering due to their permeability and biocompatibility. Those that have shear thinning properties allow for minimally-invasive surgical procedures and a way to administer bioactive agents, and therapeutic cells by injection. Currently available injectable hydrogels have a single or dual input/stimulus for crosslinking which limits the range of mechanical properties and often utilize potentially toxic ultraviolet radiation that reduces viability of injected cells. To overcome these shortcomings, a tri-stimuli-responsive alginate-based injectable hydrogel was developed based on: 1) supramolecular complex formation between β-cyclodextrin (β-CD) conjugated alginate and thermo-responsive tri-block Pluronic® copolymers, 2) visible light crosslinking via acrylate conjugation, and 3) ionic crosslinking of the alginate backbone via exposure to calcium chloride. The capabilities of the novel multi-stimuli injectable hydrogel were demonstrated with a custom microfluidic devices (MFDs) to create microspheres encapsulating human mesenchymal stem cell (MSCs). These experiments proved that the new hydrogel was capable of serving as a stimuli responsive material for MSC cell delivery in the therapeutic range of 10-1000 µm in diameter. In order to enhance the drug delivery capabilities of the hydrogel, heparin sodium was conjugated onto the alginate backbone. The affinity of the growth factor, vascular endothelial growth factor (VEGF), to the heparin helped to prevent denaturing of the protein and improved vascularization. This new tri-crosslinking hydrogel with conjugated heparin allows the end-user to control the final physicomechanical and biochemical properties of the hydrogel using different external stimuli. The tri-crosslinking hydrogel is a versatile material that has great promise for a variety of soft tissue repair applications.

Biodegradation is the breakdown of a compound by a biological organism. Over the past few decades, the biodegradation of compounds such as phenol has been researched extensively. Phenol research has shown that certain organisms are capable of utilising it as an energy source, and a variety of methods are available for its removal. Unfortunately, there is lack of research on phenol degradation at low concentrations. The majority of research performed on phenol degradation has used concentrations above 500 mg, while phenol is highly toxic at levels below 25 mg. The aim of this research was to pursue the problem of phenol degradation at below 100 mg and develop a system able to degrade phenol at such levels. The system consisted of a bioreactor developed to run in continuous mode, using Ps. putida immobilised in calcium alginate. A standard method was modified to quantitatively analyze effluent phenol levels, and a medium designed to increase the longevity of calcium alginate beads in continuous culture. A continuous flow bioreactor was also designed using an overflow weir for use with immobilised cells. Based on the results obtained, immobilisation offers increased stability and increased protection for cells under extreme conditions and is able to use higher dilution rates than cells under continuous culture / Master of Science (Hons)

Thesis (M.Sc. (Pharm.) (Pharmaceutical Chemistry))--Potchefstroom University for Christian Higher Education, 2003.

In the last few years, especially in the developed countries, an increment in demand for fresh-cut fruit by the consumers of all ages has occurred. This increase is mainly due to the importance that people are giving to the consumption of fresh, healthy, and low-calorie food products. Fresh-cut pineapple (Ananas comosus) is one of the fruits that consumers can eat quickly and still enjoy its benefits; however, its shelf-life is very short (7 days). A means to preserve all the natural and beneficial components of fresh-cut pineapple is coating the fruit with an edible material, a coating. This coating acts as a barrier against moisture loss and gas exchanges and can be a carrier of other components like antimicrobials, which can help to extend the shelf-life of the fresh-cut fruit. The main objective of this study was to develop an edible coating with an antimicrobial agent for fresh-cut pineapple and to determine its effectiveness in extending shelf-life and preserving fruit quality attributes. Different treatments consisted of several concentrations of sodium alginate (0.5%, 1%, and 2%); beta-cyclodextrin, trans-cinnamaldehyde (antimicrobial), pectin, and calcium chloride were tested for formulation of the edible coating. The layer-by-layer technique with a dipping method was used to coat the fruits. Pineapples were properly cleaned with a chlorine solution (300 ppm) and triangular prisms (3.6 cm per side) were cut using a triangular cutter. The length of the triangular prisms was adjusted to 2.54 cm using a small knife measured with a ruler. Color, texture, pH, degrees Brix (total soluble solids), acidity, vitamin C, moisture content, and weight loss, were monitored every 3 to 4 days for 15 days. Microbiological tests (aerobic plate counts, psychrotrophic counts, and yeast and molds counts) were performed to determine the effectiveness of the antimicrobial compound. In terms of microbiological and physicochemical quality attributes, the coating improved the shelf-life of the fresh-cut pineapple up to 12 days compared to the control (fresh-cut pineapple without the coating) which only lasted 7 days at 4 degrees C. Color, texture and pH, were better preserved in the treated (coated) fruit compared to controls (uncoated). Different concentrations of the solutions in the formation of the coating had different results in terms of the preservation of the quality attributes of the fruit. Antimicrobial coatings with a concentration of alginate of 1% and 2% (w/w), pectin 2% (w/w) and calcium chloride 2% (w/w) presented a satisfactory formulation to preserve fruit quality attributes like moisture content, help to control juice leakage, and avoid microbial growth. Antimicrobial coating with 1% of alginate (w/w), 2% of pectin (w/w), 2% of calcium chloride (w/w) and 2% of antimicrobial compound (w/w) was the best formulation. This research demonstrates the feasibility of an alginate-based antimicrobial edible coating, which acts as a carrier of antimicrobial compounds for fresh-cut pineapple.

Alginate is an exopolysaccharide secreted by Pseudomonas aeruginosa and is a major component of biofilms that infect the lungs of cystic fibrosis patients. Ten proteins have been implicated in alginate polymerization, modification and export, and are believed to assemble into a multi-protein complex that spans the cell envelope and coordinates the synthesis and secretion of alginate. AlgK is a protein encoded in the alginate biosynthetic operon, which is required for the secretion of high-molecular weight alginate. This study describes structural and functional studies of AlgK to improve our understanding of AlgK’s role in alginate biosynthesis. To shed light on the function of AlgK, C14-palmitic acid labeling and sucrose gradient fractionation studies confirmed that AlgK is an outer membrane lipoprotein. Cellular fractionation experiments also found that AlgK is involved in the proper localization of AlgE, the alginate secretion pore in the outer membrane. The structure of AlgK was determined to 2.5 Å resolution by X-ray crystallography and revealed that the protein folds into 22 alpha-helices that pack into a flexible right-handed solenoid. Closer examination of the amino acid sequence revealed that AlgK carries 9.5 tetratricopeptide repeat (TPR)-like elements. Given the role that TPR motifs generally play in protein-protein interaction and the assembly of multi-protein complexes, the presence of these motifs in AlgK suggests that it can bind to one or more proteins. Based on the results presented in this study, we propose that AlgK acts as a scaffold for the assembly of the alginate secretion complex. By mapping highly conserved residues onto the surface of our model, three putative sites of protein-protein interaction were identified. We hypothesize that the N-terminus of AlgK binds to AlgE in the outer membrane, and the C-terminus of AlgK binds to periplasmic and/or inner membrane Alg proteins, thereby acting as a linker between the inner and outer membrane components of the alginate biosynthetic complex. We further hypothesize that together AlgE and AlgK constitute a novel exopolysaccharide secretin. The alginate biosynthetic complex appears to be distinct from the canonical capsular polysaccharide systems currently described.

Isolation of selected populations from heterogeneous cell mixtures and retrieval of the captured population of interest for regenerative medicine and diagnostics applications is one of the challenges that may be addressed by microfluidics. An affinity adhesion strategy was tested using the tetrapeptides RGDS (arg-gly-asp-ser), REDV (arg-glu-asp-val) and VAPG (val-ala-pro-gly) to modify an alginate hydrogel surface layer to selectively adhere fibroblast (FB), endothelial (EC) and smooth muscle cell (SMC) populations, respectively, of the non-myocyte cardiac cell fraction. Incorporation of peptides into sodium alginate gel surface coatings demonstrated a preferential, seeding density-dependent adhesion relationship on alginate-RGDS when tested with a cardiomyocyte-depleted cell suspension in both static culture and in microfluidic devices. Seeding density-dependent attachment was seen with close to 100% release of viable cells from coated surfaces upon application of ethylenediaminetetraacetic acid (EDTA). Further work will optimize the system with REDV and VAPG to capture ECs and SMCs.