Tesis por compendio / The overall objective of the doctoral thesis was the development of starch-based (S) biodegradable active films for food packaging applications, by applying both casting method and thermoprocessing. Different blends of S with protein material have been studied in order to improve the functional properties of the films or confer antimicrobial/antioxidant activity. The following protein materials were used: powder buttermilk (BM); lactoferrin (LF) and/or lysozyme (LZ), and bovine gelatin (BG). Ethyl lauroyl arginate (LAE, E243) was also incorporated as antimicrobial compound. Likewise, S:BG blend films, either with or without LAE, with previously oxidized S, have been studied to enhance the crosslinking of polymer chains and to improve the film properties. The films have been characterized as to their functional properties as packaging material, their antioxidant and/or antimicrobial properties, as well as their capacity for preserving different food systems, in terms of lipid oxidation and microbial spoilage. Blends of S with BM gave rise to films with a heterogeneous structure, in which the formation of a protein gel was observed when BM dispersion was heated with S at 90 ºC for 30 min. The heat treatment promoted an increase in the resistance to break and stretchability of films, together with a decrease in water vapour permeability. Only those films subjected to heat treatment exhibited antioxidant activity, probably due to the release of active peptides as a result of high temperatures. However, no antilisterial activity was observed for any film containing BM. The incorporation of LF and/or LZ into S films, obtained by the casting method, led to a partial compatibility between polymers, thus affecting the microstructure of S films, as well as leading to an rise in the glass transition temperature. Films with proteins were less extensible, especially when LF was incorporated. All of the films tested were effective at controlling the progress of lipid oxidation in pork lard, whereas only films with LF/LZ blend reduced the growth of coliforms in minced pork meat, as a result of their synergistic action. Films based on S and BG blends (1:1) were obtained by both casting method and thermo-processing. Phase separation of both polymers (stratified structure or separated domains of both polymers, respectively) was observed in both cases. The incorporation of LZ, but mainly LAE, into films, enhanced the compatibility between polymers. Thermo-processed films were more permeable to water vapour and oxygen, less rigid and resistant and more stretchable, in comparison with those films obtained by casting. While LAE incorporation improved the water vapour barrier capacity, it worsened the oxygen barrier properties, contrary to the effect produced by LZ. All films with LAE exhibited high antilisterial activity. Films based on oxidized S and BG (1:1), obtained by casting, showed a high polymer compatibility, and crosslinking between the polymer chains occurred due to the carbonyl-amino condensation reaction. As a result, the water uptake ability of the films decreased and the mechanical and barrier properties improved, although film browning was induced due to the formation of Maillard compounds. LAE incorporation implied its involvement in condensation reactions, due to its bi-functional character (carbonyl-amino), thus affecting crosslinking and the film properties. These reactive processes progressed throughout storage time, leading to an increase in the mechanical resistance and browning of the films. The obtained Maillard compounds conferred antimicrobial capacity on the films, which increased as the storage time progressed. The application of blend films of native or oxidized S and BG with LAE, for the purposes of preserving vacuum packaged chicken breast fillets, extended the shelf-life through the inhibition of bacterial growth (total viable counts; psicrotrophic, anaerobic,lactic acid bacteria and coliforms). Samples packaged i / El objetivo general de la presente tesis doctoral se basa en el desarrollo de films activos biodegradables a base de almidón (S) para su aplicación en sistemas de envasado de alimentos, por medio de dos métodos diferentes de obtención, método en húmedo por extensión y secado (casting) y método en seco (termoprocesado). Se estudiaron mezclas de S con diferentes materiales proteicos, con fin de disminuir la alta higroscopicidad de los films de S y su retrogradación a lo largo del tiempo de almacenamiento y mejorar sus propiedades funcionales, así como conferirles actividad antimicrobiana/antioxidante. Los materiales proteicos utilizados fueron los siguientes: suero de mantequilla en polvo (BM); lactoferrina (LF) y/o lisozima (LZ), y gelatina bovina (BG). El etil lauroil arginato (LAE, E243) fue también incorporado como compuesto antimicrobiano. Asimismo, se estudiaron los films mezcla de S con BG, con y sin LAE incorporado, habiendo oxidado previamente el S, para así potenciar el entrecruzado de las cadenas poliméricas y mejorar las propiedades de los films. Estos fueron caracterizados en sus propiedades funcionales como material de envase, sus propiedades antioxidantes y/o antimicrobianas, así como por su capacidad de conservación de diferentes sistemas alimentarios, en términos de su oxidación lipídica y deterioro microbiológico. Las mezclas de S con BM dieron lugar a películas con una estructura heterogénea, en las que se observó la formación de un gel proteico como resultado del calentamiento de la dispersión BM con S a 90 ºC durante 30 min. El tratamiento térmico promovió un aumento de la resistencia a la rotura y extensibilidad de los films, junto con una disminución en la permeabilidad al vapor de agua. Sólo las películas sometidas a tratamiento térmico y homogeneización con cizalla mostraron actividad antioxidante, probablemente debido a la liberación de péptidos activos en consecuencia de la alta temperatura y fuerza de cizalla aplicada Sin embargo, no se observó actividad antilisteria para ninguno de los films con BM. La incorporación de LF y/o LZ en films de S condujo a una compatibilidad parcial entre polímeros, afectando así a la microestructura de los films de S, y produciendo un aumento de la temperatura de transición vítrea y disminución de la capacidad de alargamiento de los films, especialmente cuando se incorporó LF. Todos los films resultaron eficaces en el control del progreso de la oxidación lipídica de la manteca de cerdo, mientras que sólo las películas con mezcla LF/LZ redujeron el crecimiento de coliformes en carne picada de cerdo, como resultado de su acción sinérgica. Los films basados en la mezcla S y BG (1: 1) fueron obtenidos por casting y termo-moldeado y compresión, llevando a la separación de fases entre ambos polímeros (estructura esratificada o separación de dominios de ambos polímeros, respectivamente). La incorporación de LZ, y principalmente de LAE, en los films, aumentó la compatibilidad entre ambos polímeros. Los films termoprensados fueron más permeables al vapor de agua y al oxígeno, menos rígidos y resistentes y más extensibles, en comparación con aquellos obtenidos por casting. La incorporación de LAE mejoró la capacidad de barrera contra el vapor de agua, mientras que incurrió en un empeoramiento de la barrera frente al oxígeno, contrariamente al efecto producido por la LZ. Los films con LAE, moldeados o termoprensados, mostraron una alta eficacia antilisteria. Los films basados en S oxidado y BG (1: 1), fueron obtenidos por casting y mostraron una alta compatibilidad polimérica, lo cual condujo al entrecruzado de las cadenas como resultado de la reacción de condensación carbonilo-amino producida entre ambos polímeros. En consecuencia, la capacidad de absorción de agua de los films disminuyó y se mejoraron las propiedades mecánicas y de barrera, aunque también se indujo a un pardeamiento de los films, indicando / L'objectiu general de la tesi doctoral és el desenvolupament de films actius biodegradables a base de midó (S) per a la seua aplicació en sistemes d'envasat d'aliments, amb l'utitització del mètode d'extensió i assecat (casting) i termoprocessat (barrejat en fos i termo-compressió). Es van estudiar barreges de S amb diferents materials proteics, per millorar les propietats funcionals dels films o conferir activitat antimicrobiana. Els materials protèics utilitzats van ser: sèrum de mantega en pols (BM); lactoferrina (LF) i/o lisozima (LZ), i gelatina bovina (BG). L'ètil lauroil arginat (LAE, E243) va ser també incorporat com a compost antimicrobià. Així mateix, es van estudiar els films barreja de S amb BG, amb i sense LAE, havent oxidat prèviament el S, per potenciar l'entrecreuat de les cadenes polimèriques i millorar les propietats dels films. Aquests van ser caracteritzats en les seues propietats funcionals com a material d'envàs, les seues propietats antioxidants i/o antimicrobianes, així com en la seua capacitat de conservació en diferents sistemes alimentaris, en termes de la seua oxidació lipídica i deteriorament microbià. Les barreges de S amb BM van donar lloc a films amb una estructura heterogènia, en què es va observar la formació d'un gel protèic com a resultat del calfament de la dispersió BM amb S a 90 ºC durant 30 min. El tractament tèrmic va promoure un augment de la resistència al trencament i extensibilitat dels films, juntament amb una disminució en la permeabilitat al vapor d'aigua. Només el films sotmesos a tractament tèrmic van mostrar activitat antioxidant, probablement a causa de l'alliberament de pèptids actius com a conseqüència de l'alta temperatura. No obstant això, no es va observar activitat antilisteria per cap dels films amb BM. La incorporació de LF i/o LZ en films de S obtinguts per casting va donar lloc a una compatibilitat parcial entre polímers, afectant a la microestructura dels films de S, i produint un augment de la temperatura de transició vítria. Els films amb les proteïnes van ser menys extensibles, especialment quan es va incorporar LF. Tots els films van resultar eficaços en el control de l'oxidació lipídica de la mantega de porc, mentre que només el films amb barreja LF/LZ van reduir el creixement de coliforms en carn picada de porc, com a resultat de la seua acció sinèrgica. Els films amb barreges S i BG (1: 1) van ser obtinguts per casting i termo-processat. En tots dos casos es va observar separació de fases entre els dos polímers (estructura estratificada o separació de dominis d'ambdós polímers, respectivament). La incorporació de LZ, i principalment de LAE, en els films, va augmentar la compatibilitat entre tots dos polímers. Els films termo-processats van ser més permeables al vapor d'aigua i l'oxigen, menys rígids i resistents i més extensibles, en comparació amb els obtinguts per càsting. La incorporació de LAE va millorar la capacitat de barrera al vapor d'aigua, a l'hora que va disminuir la capacitat de barrera davant l'oxigen, contràriament a l'efecte produït per la LZ. Tots els films amb LAE, van mostrar una alta capacitat antilisteria. Els films amb S oxidat i BG (1: 1), van ser obtinguts per casting i van mostrar una alta compatibilitat dels polímers, tot produint entrecreuat de les cadenes com a resultat de la reacció de condensació carbonil-amino. En conseqüència, va disminuir la capacitat d'absorció d'aigua dels films i es van millorar les propietats mecàniques i de barrera, encara que es va promoure l'enfosquiment dels films, cosa que indica la formació de compostos de Maillard. La incorporació de LAE va implicar la seua participació en les reaccions de condensació, a causa del seu caràcter bi-funcional (carbonil-amino), el que va afectar a l'entrecreuat i les propietats dels films. Aquests processos reactius van progressar al llarg del temps d'emmagatzematge, donant lloc a un augment de l / Moreno Marro, O. (2017). Starch-protein active films for food preservation [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80616 / Compendio

Yes / Antimicrobial resistance (AMR) is a growing global crisis with an increasing number of untreatable or exceedingly difficult-to-treat bacterial infections, due to their growing resistance to existing drugs. It is predicted that AMR will be the leading cause of death by 2050. In addition to ongoing efforts on preventive strategies and infection control, there is ongoing research towards the development of novel vaccines, antimicrobial agents, and optimised diagnostic practices to address AMR. However, developing new therapeutic agents and medicines can be a lengthy process. Therefore, there is a parallel ongoing worldwide effort to develop materials for optimised drug delivery to improve efficacy and minimise AMR. Examples of such materials include functionalisation of surfaces so that they can become self-disinfecting or non-fouling, and the development of nanoparticles with promising antimicrobial properties attributed to their ability to damage numerous essential components of pathogens. A relatively new class of materials, metal-organic frameworks (MOFs), is also being investigated for their ability to act as carriers of antimicrobial agents, because of their ultrahigh porosity and modular structures, which can be engineered to control the delivery mechanism of loaded drugs. Biodegradable polymers have also been found to show promising applications as antimicrobial carriers; and, recently, several studies have been reported on delivery of antimicrobial drugs using composites of MOF and biodegradable polymers. This review article reflects on MOFs and polymer-MOF composites, as carriers and delivery agents of antimicrobial drugs, that have been studied recently, and provides an overview of the state of the art in this highly topical area of research.

Different structures of non-viral cationic polymer delivery vehicles, including charge center type, molecular weight and degradability, could significantly affect toxicity, release of nucleic acid and transfection efficiency. Poly(glycoamidoamine)s (PGAAs) contained different carbohydrate and secondary amine moieties and showed high transfection efficiency to different cell lines in a nontoxic manner. The "proton sponge hypothesis" has attempted to relate the buffering capacity to endosomal release of polyethylenimine (PEI) based polyplexes, which could contribute to high transfection efficiency. Secondary amine structures rendered PGAAs buffering capacity around physiological pH. To test the feasibility of the mechanism for PGAAs, new no buffering capacity guanidine or methylguanidine containing poly(glycoamidoguanidine)s (PGAGs) were synthesized. PGAGs formed stable polyplexes with pDNA from N/P (# secondary amine or guanidine group on polymer backbone / # phosphate group on pDNA backbone) ratio 3. PGAG based polyplexes expressed low cytotoxicity and were internalized by 90% of cells at N/P 25. Furthermore, two PGAG based polyplexes showed higher transfection efficiency from N/P 5 to 30 than their PGAA based analogs. These data suggested the low transfection could be due to the difficulties to release pDNA from polyplexes; also, the "proton sponge theory" could not explain the higher transfection efficiency by some PGAGs. Degradation of delivery vehicles could potentially release pDNA in cells and increase transfection efficiency. PGAAs degraded rapidly at physiological conditions and the proposed mechanism was amide hydrolysis. Typically, amide groups are stable and hydrolyze slowly in absence of enzyme. Different models mimicking PGAAs were synthesized to study the fast hydrolysis. Amide groups showed asymmetric hydrolysis. Different hydrolysis behaviors suggested neighboring group participation of two terminal groups to induce rapid amide hydrolysis. These new models could potentially be used to design new polymer delivery vehicles with various degradation profiles. / Master of Science

Broilers are raised indoors on high density farms with bedding/litter to trap their manure. Ammonia gas, which is produced as the manure decomposes, has adverse effects on human health, bird welfare and the environment. Using litter amendments can reduce the amount and, consequently, the effects of ammonia emitted from broiler houses. The objective of this study was to determine the effectiveness of a biodegradable litter amendment (BLA) in reducing ammonia emitted from a broiler house. A pilot scale test was set up with six adjacent, individually ventilated rooms and a stocking density of 0.07 m² per bird. The birds were fed with a standard commercial, corn and soybean meal based diet and water was provided ad libitum. The first flock was grown on 10 cm of fresh, kiln-dried pine shavings, while subsequent flocks were grown on top-dressed reused litter. The two treatments (control (CTL) and BLA) were randomly assigned to the six rooms after flock 1, to give three replicates per treatment. The exhaust air from the rooms was sampled for ammonia concentration for two days each week starting at four days of age to determine the amount of ammonia emitted. Over three subsequent flocks, the total mass of ammonia emitted from rooms treated with BLA was 31% to 47% lower than the control. Ammonia emitted per bird grown on treated litter and per kg of harvested bird weight was 32% to 44% lower, and the exhaust fans ran 7% to 22% less than CTL over the same period. For both BLA and CTL, the amount of ammonia emitted generally increased with bird age and litter reuse. The study showed that BLA effectively reduced ammonia emitted from a broiler house and that there are potential energy savings from using the amendment. However, ammonia emitted from the BLA rooms during the final flock was 57% higher than CTL, which was attributed to insufficient water (less than 18% moisture by weight) to support the reaction between BLA and ammonia. / Ph. D.

Currently growth plate fractures account for nearly 18.5% of fractures in children and can lead to stunted bone growth or angular deformation. If the body is unable to heal itself a bony bar forms, preventing normal bone growth. Clinical treatment involves removing the bony bar and replacing it with a filler substance, which causes poor results 60% of the time. Using primarily poly(lactic-co-glycolic acid) (PLGA) as the scaffold material, the goal was to develop an implant that would support to the implant site, allow for cell ingrowth, and degrade away over time. Porous scaffolds were fabricated from PLGA microspheres using the salt leaching method. The first part of this work investigated the effect of sintering the microspheres by studying the mechanical properties, degradation and morphology and their potential applications for hard and soft tissue implants. Growth factor or drugs can be encapsulated into PLGA microspheres, which was the second part of this work. Encapsulated insulin-like growth factor I (IGF-I) was able to withstand the scaffold fabrication process without compromising it’s bioactivity and promoted cell proliferation. The next part of this work experimented with the addition of a hydrogel porogen. Porogen particles were made using a quick degrading poly(beta-amino ester) (PBAE) hydrogel and loaded with ketoprofen. The addition of the porogen creates a dual drug-releasing scaffold with a localized delivery system. The final step of this work involved animal studies to determine the effectiveness of the scaffolds in growth plate regeneration and how they compare to the current clinical treatment option. Gross observation, microCT analysis, angular measurement of bone growth and histological methods were employed to evaluate the scaffolds. The goal was to develop a versatile scaffold that could be used for a wide range of tissue engineering applications. The mechanical properties, degradation profiles and drug delivery capabilities can be all tailored to meet the specific needs of an implant site. One specific application was regenerating the native growth plate that can also encourage the endogenous mesenchymal stem cells to follow the desire linage. By regenerating the native growth plate, angular deformation and stunted limb growth were greatly reduced.

In situ forming implants (ISIs) are popular due to their ease of use and local drug delivery potential, but they suffer from high initial drug burst, and release behavior is tied closely to solvent exchange and polymer properties. Additionally, such systems are traditionally viewed purely as drug delivery devices rather than potential scaffold materials due to their poor mechanical properties and minimal porosity. The aim of this research was to develop an injectable ISI with drug release, mechanical, and microstructural properties controlled by micro- and nanoparticle additives. First, an injectable ISI was developed with appropriate drug release kinetics for orthopedic applications. Poly(β-amino ester) (PBAE) microparticles were loaded with simvastatin or clodronate, and their loading efficiency and drug retention after washing was quantified. Drug-loaded PBAE microparticles and hydroxyapatite (HA) microparticles were added to a poly(lactic-co-glycolic acid) (PLGA)–based ISI. By loading simvastatin into PBAE microparticles, release was extended from 10 days to 30 days, and burst was reduced from 81% to 39%. Clodronate burst was reduced after addition of HA, but was unaffected by PBAE loading. Scaffold mass and porosity fluctuated as the scaffolds swelled and then degraded over 40 days. Next, the mechanical properties of these composite ISIs were quantified. Both micro- and nanoparticulate HA as well as PBAE microparticle content were varied. Increasing HA content generally improved compressive strength and modulus, with a plateau occurring at 30% nano-HA. Injectability remained clinically acceptable for up to 10% w/w PBAE microparticles. Ex vivo injections into trabecular bone improved both strength and modulus. Lastly, HA-free ISIs were investigated for drug delivery into the gingiva to treat periodontitis. Doxycycline and simvastatin were co-delivered, with delivery of doxycycline over 1 week accompanied by simvastatin release over 30 days. PBAE-containing ISIs exhibited higher initial and progressive porosity and accessible volume than PBAE-free ISIs over the course of degradation. Additionally, PBAE-containing ISIs provided superior tissue retention within a simulated periodontal pocket. The ISIs investigated here have a wide range of potential applications due to their flexible material and drug release properties, which can be controlled by both the chemistry and concentration of various particulate additives.

Orientador: Ana Rita Morales / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T21:17:33Z (GMT). No. of bitstreams: 1 Pinheiro_IvaneiFerreira_M.pdf: 6507466 bytes, checksum: 544ce949996ee364af7bcc47e112b2ec (MD5) Previous issue date: 2012 / Resumo: Neste trabalho estudou-se biocompósitos poliméricos obtidos a partir de um poliéster biodegradável e fibra natural de Munguba (Pseudobombax munguba) nativa da região amazônica. Trata-se de uma fibra de grande abundância encontrada nas regiões alagadiças da floresta, para a qual não existem relatos na literatura de sua utilização em biocompósitos poliméricos. Estudou-se a influência do tamanho da fibra, da concentração, e de tratamentos químicos na superfície da fibra, sobre as propriedades finais dos biocompósitos. As fibras naturais foram moídas e classificadas por tamanho e submetidas a tratamentos químicos. A fim de avaliar as modificações promovidas pelos tratamentos empregados, as propriedades mecânicas, morfologia e propriedades de superfície foram analisadas. A análise por Espectroscopia no Infravermelho (FTIR) mostrou o aparecimento de grupos ésteres confirmando a troca de hidroxila por acetila. Os ensaios mecânicos de tração mostraram que a modificação química proporcionou aumento de 75% no módulo elástico da fibra. Pelas análises de morfologia e de ângulo de contato, foram verificadas alterações superficiais significativas da fibra de munguba, enquanto que a análise termogravimétrica (TGA) mostrou que a modificação química aumentou a estabilidade térmica em comparação com a fibra natural. Os biocompósitos foram preparados por mistura em alto cisalhamento no estado fundido, utilizando fibras naturais e quimicamente tratadas com teores de 10 e 20% variando-se o tamanho das fibras. Os resultados indicaram que o aumento na concentração de fibra foi a principal responsável pelas mudanças nas propriedades mecânicas. As análises morfológicas mostraram que os tratamentos químicos não foram eficazes em promover boa interação fibra-matriz. Modelos mecânicos foram usados para prever o módulo de elasticidade dos biocompósitos sendo que o modelo de Russell descreveu com boa adequação os sistemas estudados. Através da calorimetria exploratória diferencial (DSC) verificou-se que a adição de fibras provocou alterações na cristalinidade, diminuição na temperatura de fusão e aumento na temperatura de cristalização na matriz / Abstract: In this work it was studied polymer biocomposites made from a biodegradable polyester and natural fiber Munguba (Pseudobombax Munguba) native to the Amazon region, found in great abundance marshy areas of the forest, for which there are no literature reports of its use in polymer biocomposites. The effects of fiber size, concentration and chemical treatment on the fiber surface on the final properties of the biocomposites were studied. The natural fibers have been milled and classified by size and subjected to chemical treatment. In order to evaluate the changes promoted by employed treatment, the mechanical properties, surface properties and morphology were evaluated. Infrared Spectroscopy (FTIR) analysis showed the appearance of ester groups to hydroxyl confirming the exchange by acetyl. By the tensile strength tests showed that the chemical modification time increased by 75% the elastic modulus of the fiber. The analysis of the morphology and the contact angle, significant surface changes were observed in the Munguba fiber, whereas the thermogravimetric analysis (TGA) showed that the chemical modification increased the thermal stability in comparison to the natural fiber. The biocomposites were prepared by high shear mixing in the molten state using natural, and chemically treated fibers with levels of 10 and 20% varying the size of the fibers. The results indicated that increasing the concentration of fiber was mainly responsible for the changes in mechanical properties. The morphological analysis showed that the chemical treatments were not effective in promoting good fiber-matrix interaction. Mechanical models were used to predict the elastic modulus of the biocomposites and the model of Russell presented a good fit to the studied systems. By differential scanning calorimetry (DSC) showed that the addition of fibers caused changes in crystallinity decrease in melting temperature and crystallization temperature increase in the matrix / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Environmental concerns arising from the use of non-degradable plastics have resulted in search for suitable substitutes. The thesis deals with new nanostructured composites based on reinforcement of nanocellulose whiskers in "green" polymers such as xylan. Since the reinforcement filler and the matrix are both biobased and are thereby environmental friendly. Xylan incorporated with cellulose whiskers films provided with improved water and oxygen barrier properties. It appears that the high degree of crystallinity of cellulose whiskers, dense composite structure formed by the whiskers and rigidly hydrogen-bonded cellulose whiskers can cause cellulose whiskers to form integrated matrix which contribute to substantial benefit in the overall reduction of transmission rate. The spectral data obtained for the NCW/xylan nanocomposite films showed that the amount of xylan adsorbed to cellulose increases with the addition of NCW in the matrix. In addition, NMR T2 relaxation experiments studies were conducted to investigate the change in the nature of carbohydrate-water interactions as a result of NCW incorporation. These results facilitated an improved understanding of the mechanisms involved in the superior barrier and mechanical properties of xylan-whisker nanocomposite films. XRD studies show that when a xylan-whisker nanocomposite films is formed the mixing occurs on the atomic scale and NCW loading increases the matrix crystallinity.