In recent years, the application of microparticles in different fields including cosmetics, agriculture, pharmaceutics and biomedicine has been widely investigated.In this project, we aimed to improve the preparative methods for chitosan–triphosphate microparticles (Cs/TPP) for perspective application in the fields of cell encapsulation and controlled drug delivery. Prior to the preparation of chitosan-based microparticles, in order to confirm good biocompatibility and reproducibility, protocols have been established for the purification and characterisation of chitosan including the assessment of average molecular weight, protein content and degree of deacetylation.This study then primarily focused on the use of β-glycerophosphate (βGP) as an excipient, which is known to solubilize chitosan at neutral pH, thus allowing the preparation of chitosan microparticles (microspheres and toroidal) via ionotropic gelation under physiological conditions. The preparation of Cs-βGP/TPP microparticles was optimized varying several key process variables (concentration, flow rate, and frequency) and these microparticles were produced with a narrow size distribution (400 – 500 μm, spherical shape) and compared to Cs/TPP controls. The main result was the possibility to perform this process at neutral pH, although we have also demonstrated an improved toughness and cross-linking density of these microspheres as a result of the presence of β-glycerophosphate. Further, we have investigated the application of this method to a toroidal geometry, which provides advantages in terms of better transfer of oxygen and nutrients to any encapsulated materials. Cs/TPP and Cs-βGP/TPP ‘micro-doughnuts’ were also prepared and characterised. This research highlighted the evidence of a higher cross-linking density of these microparticles in comparsion with the spherical ones. In order to optimise the physicochemical characteristics of these microparticles for future applications as biomaterials, the surface of Cs/TPP and Cs-βGP/TPP microparticles was modified through an additional polyelectrolyte complexation with poly (sodium 4- styrene sulphonate) (PSS). The improved toughness and cross-linking density was confirmed by measuring the mechanical properties and solid content which indicated the successful complexation of PSS onto the surface of these microparticles.

The kinetics of the reaction catalyzed by acyl-CoA: sn-glycerol-3-phosphate O-acyltransferase solubilized from Euglena gracilis microsomes were examined. For myristoyl-, palmitoyl-, stearoyl-, and oleoyl-CoAs, the initial reaction rates rose with increasing substrate concentration up to an optimal concentration that varied from 18.5 to 25 μ M, well above the respective critical micelle concentrations. At higher substrate concentrations, reaction was progressively inhibited. Arachidoyl-CoA was a relatively poor substrate for the acyltransferase, and substrate inhibition was not seen with it. Km values for acyl-CoAs ranged from 13 to 20 μ M while the corresponding V values varied almost 40-fold. Bovine serum albumin, among other effects, caused a change in the kinetic pattern of the reaction acyl-CoA dependency. Both acyl-CoA micelles and albumin-bound acyl-CoA were substrates. The binding of palmitoyl- and oleoyl-CoA was 2.7 and 1.5 mol, respectively, per mol of albumin. The critical micelle concentration of palmitoyl-CoA under the reaction conditions was shown by low angle light scattering photometry to be 7.1 p.M. The sn-glycerol 3-phosphate concentration dependency of the acyltransferase initial velocity exhibited Michaelis-Menten kinetics with Km values of 1.3 and 2.9 mM in the presence of 12.5 and 25 μM palmitoyl-CoA, respectively. The substrate analogues sn-glyceraldehyde 3-phosphate and dihydroxyacetone phosphate inhibited the reaction.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-03-23T14:13:06Z No. of bitstreams: 1 PGCS16DA032.pdf: 1339120 bytes, checksum: 74d6849cd1ae7189a7da15dd6dcd242e (MD5) / Made available in DSpace on 2018-03-23T14:13:06Z (GMT). No. of bitstreams: 1 PGCS16DA032.pdf: 1339120 bytes, checksum: 74d6849cd1ae7189a7da15dd6dcd242e (MD5) Previous issue date: 2016-02-11 / Capes / Phosphorus (P) is the nutrient that most limit productivity in tropical and subtropical soils occurring as in organic form as in the inorganic form with different labilities; little is known in what conditions these organic forms of P can be available to plants after mineralization. The aim of this study was to evaluate the utilization of organic phosphorus by corn and wheat in soils with different initial levels of labile phosphorus. Two soils were used (sandy and clayey texture) both with "very low" initial level of phosphorus. The soils were ground, sieved and incubated for 30 days with lime and superphosphate rates to raise the pH to 6.0 and available P to "low", "medium" and "high"Contents. Soil treatments consisted in a factorial arrangement (4x4) with four replications: factor 1 - Initial phosphorus contents "very low", "low", "medium" and "high"; factor 2 - additional phosphate fertilizer with the following P sources: control (no additional P use); use of organic phosphorus with low degradability (phytic acid); use of organic phosphorus with high degradability (glycerolphosphate); use ofof soluble inorganic phosphorus (PA reagent). The P sources were applied at a rate equivalent to 125 kg ha-1 of P2O5. In the sandy soil it was grown corn (Zea mays) followed by wheat (Triticum aestivum) and in the clayey soil it was grown corn. After each crop it were measured dry matter production of shoot and root; P absorbed by plants and soil Pby chemical fractionation. Plants of corn and wheat responded linearly to the increase of P availability but there was no interaction between treatments.Corn and wheat respond to application of P-glycerophosphate, contributing to the P absorption by plants, higher than or similar to soluble source. The P-glycerophosphate was detected in the inorganic fractions of labile P, showing that there was mineralization while the P-phytic was mainly found in the moderately and no labile organic fractions, demonstrating its adsorption to the soil and low lability / O fósforo (P) geralmente é um dos nutrientes que mais limita a produtividade em solos tropicais e subtropicais, ocorrendo tanto em formas orgânicas quanto na forma inorgânica e com diferentes labilidades. Mas é pouco sabido em que condições essas formas orgânicas de P podem ser, após mineralização, utilizadas pelas plantas. O objetivo desse estudo foi avaliar a disponibilidade de fontes orgânicas de fósforo por plantas de milho e trigo em solos com diferentes teores iniciais de fósforo. Foi conduzido um experimento um experimento em vasos em dois solos, um de textura arenosa e um de textura média, ambos com teor “muito baixo” de fósforo. Os solos foram moídos, tamisados e, posteriormente, incubados por 30 dias com calcário e doses de superfosfato triplo para elevar o pH até 6,0 e os teores de P até os níveis “baixo”, “médio” e “alto”, respectivamente. Após nova secagem e moagem do solo, foram constituídos os seguintes tratamentos, em esquema fatorial (4x4), com quatro repetições: Fator 1 – níveis iniciais de fósforo “muito baixo” “baixo”, “médio” e “alto”; Fator 2 – adubação fosfatada suplementar com as seguintes fontes de P: testemunha (sem adição de P); adição de P orgânico de baixa labilidade (ácido fítico); adição de ácido orgânico de alta labilidade (glicerolfosfato); adição de P inorgânico solúvel (reagente PA). As fontes de P do fator 2 foram aplicadas em dose equivalente a 125 kg ha-1 de P2O5. No solo arenoso, foi cultivado milho (Zea mays L.) seguido por trigo (Triticum aestivum L.) e no argiloso foi cultivado milho. Após cada cultivo foram medidos a produção de massa seca de parte aérea e raízes, o teor de P absorvido pelas plantas e no solo foi realizado fracionamento químico das formas de P. As plantas de milho e de trigo responderam linearmente ao incremento de disponibilidade de P, mas não houve interação entre os fatores estudados. As plantas de milho e de trigo responderam à aplicação de P-glicerolfosfato, sendo que contribuiu para a nutrição das plantas de milho, sendo superior ou semelhante à fonte solúvel. O P-glicerolfosfato foi detectado nas frações inorgânicas de P lábil, mostrando que houve mineralização, enquanto o P-fitico foi constatado principalmente nas frações orgânicas moderadamente lábeis e não lábeis, evidenciando sua adsorção com os constituintes do solo e sua baixa labilidade

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Synthesis of ternary polyurethanes (PUs) from hexamethylenediisocyanate, β- cyclodextrin and β-glycerophosphate (acid and calcium salt) was studied varying synthesis parameters such as monomer proportion, heating method (reflux and microwave), and catalyst amount. Favorable conditions were provided by microwave irradiation and use of β-glycerophosphoric acid although the results suggest that it is possible to obtain ternary PUs with the calcium salt. FTIR data indicated the existence of secondary urea linkages. After characterization of ternary PUs by FTIR spectroscopy, XRD and thermal analysis, as well as evidences that the cyclodextrin cavities remained active toward inclusion of guest molecules, the possibility of inclusion of the antibiotic ciprofloxacin was evaluated. Absence of ciprofloxacin melting peak in DSC curves indicated that it is molecularly dispersed within the polymer, possibly included in the cyclodextrin. In vitro release experiments suggested additional non-inclusion interactions, showing also that the use of dialysis membranes may mask the actual release profile. / Nesta Tese foi estudada a síntese de poliuretanos ternários (PUs) à base de diisocianato de hexametileno, β-ciclodextrina e β -glicerofosfato (na forma de ácido e de sal de cálcio), sendo avaliados diferentes parâmetros de síntese, tais como proporção monômero, método de aquecimento (refluxo e microondas), bem como a quantidade de catalisador. As condições mais favoráveis foram fornecidas pela irradiação de microondas e a utilização de ácido β -glicerofosfórico, embora os resultados sugiram que é possível obter PU ternário com o sal de cálcio. Dados de FTIR indicaram a existência de ligações de uréia secundárias na estrutura dos poliuretanos. Após a caracterização dos PU’s ternários por espectroscopia de FTIR, XRD e análise térmica, obtiveram-se evidências de que as cavidades de β-ciclodextrina permaneceram ativas para a inclusão de moléculas hóspedes, usando-se fenolftaleína (FF) como sonda. Na seqüência, foi avaliada a possibilidade de inclusão do antibiótico ciprofloxacina. A ausência do pico de fusão ciprofloxacina em curvas de DSC indicou que este fármaco está molecularmente disperso dentro do polímero, com as moléculas possivelmente incluídas nas cavidades β-ciclodextrina. Experiências de liberação in vitro sugeriram interações não-inclusivas, mostrando também que a utilização de membranas de diálise pode mascarar o perfil de liberação efetiva.