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<p>DNA interstrand cross-links (ICLs) constitute one of the most severe types of DNA damage. ICLs covalently tether both strands of duplex DNA, preventing unwinding and polymerase access during replication and transcription. This obstruction is exploited in cancer chemotherapy since it leads to replication fork collapse, double strand breaks (DSBs), and cell death. Mechanistic understanding of how eukaryotic cells repair these specific lesions, however, is still in its infancy. It is understood that ICL repair consists of a multitude of intersecting and connecting repair pathways that rely on interplay between critical protein factors. Interestingly, Pso2 has been identified as an integral component of the ICL repair pathway in <em>Saccharomyces cerevisiae</em>. Pso2 is a yeast nuclease from the β-CASP family of proteins that function predominantly in the repair of ICLs. It has been recognized as the only protein that does not serve a redundant function in any other DNA repair pathway. It remains unclear how the ICL repair pathway generates DNA intermediates suitable for high fidelity repair dependent on Pso2 nuclease activity. Here we show that Pso2 possesses structure-specific endonuclease activity that may be essential to its role in ICL repair. Direct <em>in vitro</em> activity assessment of the protein on a site-specific ICL proved to be inconclusive due to the heat-labile nature of the cross-linking agent employed. <em>In vitro </em>activity testing was also performed on various substrates resembling intermediates generated during ICL repair. Biochemical analysis demonstrated that Pso2 cleaves hairpins, stem loops, heterologous loops, and symmetrical bubbles. Although the precise cleavage sites vary between substrates, Pso2 demonstrates preference for the single- to double-stranded junction in the DNA backbone, with similar activity to that previously demonstrated for its human homologue, Artemis. This specific endonuclease activity is stimulated by increased concentrations of phosphate. Through two-dimensional gel electrophoresis, the presence of unique DNA intermediates generated in response to ICL damage <em>in </em><em>vivo </em>was also monitored. Results suggest the generation of hairpin-like intermediates that resemble those tested <em>in vitro</em>. These intermediates persist in the absence of Pso2 but are resolved by exogenous addition of control endonucleases. Our findings expand on previous data that established hairpin-opening activity for this protein and suggest that the structure-specific endonuclease activity demonstrated by Pso2 is important for ICL repair. We anticipate that Pso2 acts on a hairpin-containing DNA substrate in the ICL repair pathway and the resolution of this intermediate is uniquely dependent on Pso2 for the effective repair of ICL damage in yeast. Taking into consideration the current models of ICL repair, both in yeast and humans, possible roles for Pso2 have been described. Achieving a complete mechanistic perspective of this pathway is critical for the therapeutic exploitation of the human homologue, SNM1A. Implications include the potential inhibitory target for increased efficacy of chemotherapy with cross-linking agents.</p> / Master of Science (MSc)

Polymer matrices are commonly used as guest-host systems for organic chromophores for use in non-linear optical materials. The chromophores must be aligned or poled in an electric field in order to impart anisotropy and non-linear activity to the material. This poling process raises several issues, the two largest being the eventual relaxation of the chromophores back into random orientations due to brownian motion, and high molecular weight polymer matrices limiting chromophore mobility during poling. The prevention of this relaxation process is an area of significant interest, especially in applications that require long term coating stability and activity. In this study, a polymer matrix is synthesized that seeks to solve both of these problems with one system. The ideal system would be one that allows for chromophore mobility during processing, but once chromophores have reached the desired orientation, limits mobility and relaxation during in-service usage. A copolymer of methyl methacrylate and a Diels-Alder adduct cross-linking monomer was synthesized in order to meet these challenges. This polymer was blended with commercially available acrylic polymer and organic chromophore molecules in order to test the viability of the solution. It was found that at the percent composition of cross-linker being utilized in the study, the Diels-Alder linkages were not reforming in any measurable amount due to the low amount of Diels-Alder active monomer units. This led to the development of a new system based on mixing polyfuran based polymers with polymaleimide based polymers during processing. This method allows for high amounts of cross-linking after processing ceases, which achieves both initial goals of the project, as well as allowing facile synthesis of the desired polymer components. Another attempt to address these issues in polymer matrix formation led to the use of a novel inimer system. The cross-linking agent was also the polymerization initiator, and these functionalities were separated by a Diels-Alder linkage that would fall apart upon exposure to thermal stimulus. These polymers were synthesized and isolated easily, although in some cases gelation occurred. In order to observe the extent of the cross-linking inimer being incorporated into the matrix, cleavage experiments were performed to induce the breaking of the Diels-Alder adduct. Analyzing the Diels-Alder cleaved polymer led to an interesting result: all polymers showed an increase in apparent molecular weight when analyzed by gel permeation chromatography. The increase in molecular weight occurring upon cleavage of main chain bonds has never before been observed in literature. The explanation proposed was that the polymer adopted a "ropeball" like topology consisting of tightly coiled loops and knots. Upon cleavage of the cross-links, the ropeball was able to unwind into a much more linear topology, occupying a much larger hydrodynamic volume. This increase in hydrodynamic volume would cause the gel permeation chromatography results to show an apparent increase in molecular weight.

Abasic sites (Ap site, from apurinic/apyrimidinic) are one of the most common lesions generated in DNA by spontaneous base loss or DNA repair processes. There are two equilibrating forms of an Ap site - ring-open aldehyde and cyclic hemiacetal. Ring- opened aldehydes are reactive electrophilic groups capable of formation covalent adduct with nucleophilic sites in DNA. DNA interstrand cross-link (ICL) resulting from the Ap sites is formed spontaneously as a covalent bond between ring-open aldehyde and amin group of adenin residue in the opposite strand of double stranded DNA. ICLs block DNA replication and transcription. The formation of Ap site derived ICL is relatively long process taking several hours. We assume that the ring-opening of an abasic site is the rate-limiting step in the formation of the thermodynamic ICL. However, formation, stability and DNA repair of Ap-ICL are still poorly understood processes. Here, I have set up mechanistic in vitro experiments to reveal and calculate the probability of Ap-ICl formation in vivo. In more detail, I study the rates of formation of Ap-ICLs in the sequence context of neighbouring nucleotides of freshly formed covalent bond of ICL. I focus on sequence preference, the influence of AT/ GC rich regions and the length of oligonucleotides. I have...

Orientador: Flavia Maria Netto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-20T14:16:39Z (GMT). No. of bitstreams: 1 VillasBoas_MarianaBattaglin_D.pdf: 3357506 bytes, checksum: 10d878e81440a9db2f379bd1dd93146f (MD5) Previous issue date: 2012 / Resumo: Tratamento térmico, alta pressão ou hidrólise enzimática, utilizados em conjunto ou separadamente, podem alterar determinantes antigênicos (epítopos) presentes nas proteínas, e têm sido estudados como estratégia para obtenção de produtos com menor potencial alergênico, porém ainda com sucesso limitado. A enzima transglutaminase (TG), que catalisa a reação de ligação cruzada inter ou intramolecular em diversas proteínas, também tem sido utilizada com este propósito. A associação da hidrólise enzimática com a polimerização por TG é uma estratégia ainda pouco explorada, mas que oferece boas perspectivas em relação à redução da antigenicidade de proteínas. Diante disso, o presente estudo teve como objetivos obter e caracterizar a ß-Lactoglobulina (ß-Lg) polimerizada por TG e a ß-Lg polimerizada pré e pós hidrólise enzimática com as proteases Alcalase, Neutrase ou bromelina, e avaliar o efeito destes processos na antigenicidade da proteína. A melhor condição de hidrólise da ß-Lg, com cada uma das proteases estudadas foi definida a partir de um delineamento composto central rotacional (DCCR), tendo como variáveis independentes a concentração de proteína (2,2 -7,8% p/v) e relação enzima : substrato (E:S), 6,9 - 28 U g-1 proteína e, como variável dependente o grau de hidrólise (GH), determinado pelo método pH-stat. A condição selecionada, 3% de proteína e E:S 25 U g-1, foi a utilizada para a hidrólise da ß-Lg pré ou pós polimerização com a enzima TG. As condições experimentais foram: (1) hidrólise da ß-Lg com as três enzimas, seguida de polimerização com TG (10 ou 25 U g-1) ou (2) polimerização da ß-Lg (7%p/v) com TG (10U TG g-1) realizada pós tratamento térmico ou na presença de agente redutor Cys (0,1 mol L-1), seguido por hidrólise com as diferentes proteases. As amostras hidrolisadas e as polimerizadas pré ou pós hidrólise foram caracterizadas por eletroforese SDS-PAGE/tricina, cromatografia líquida de alta eficiência de fase reversa (CLAE-FR), cromatografia líquida acoplada à espectrometria de massas (MS) e ensaios imunoquímicos (ELISA e Imunoblote). Os hidrolisados obtidos com Alcalase apresentaram 12,7% de GH e com Neutrase e bromelina aproximadamente 4%. Os perfis eletroforéticos da ß-Lg polimerizada pós tratamento térmico (ß-Lg TT TG) ou na presença de Cys (ß-Lg Cys TG), apresentaram bandas de massa molecular (MM) alta, porém a polimerização pós hidrólise, avaliada por eletroforese e cromatografia, não resultou em aumento da MM aparente dos hidrolisados. A ligação isopeptídica e-(?-Gln)Lys, catalisada pela TG, foi detectada em concentração mais elevada no material polimerizado pós hidrólise com alcalase, seguido do tratamento de polimerização da presença de Cys. No estudo da polimerização pré hidrólise, a alcalase foi a enzima que hidrolisou mais eficientemente tanto a ß-Lg como seus polímeros. Os polimerizados pre ou pós hidrólise com neutrase ou bromelina apresentaram ß-Lg residual, observada no perfil eletroforético e cromatográfico, sendo que para os hidrolisados com neutrase, a fração correspondente à ß-Lg residual apresentou maior intensidade. O tratamento isolado de hidrólise, principalmente com alcalase ou bromelina, ou a associação deste processo com a TG foram capazes de reduzir significativamente a resposta antigênica da ß-Lg. Os hidrolisados da ß-Lg com neutrase apresentaram reação antígeno-anticorpo apenas na região correspondente ao monômero da ß-Lg, sendo que a reação foi menos intensa após a polimerização do hidrolisado com a TG. As amostras foram submetidas à digestão in vitro e avaliadas por espectrometria de massas (MS/MS) quanto à identificação de epítopos lineares. Verificou-se que tanto a ß-Lg polimerizada após tratamento térmico ou na presença de Cys como a amostras polimerizadas pré ou pós hidrólise com bromelina apresentaram alguns fragmentos correspondentes aos epítopos, embora em menor número quando comparados aos epítopos identificados na ß-Lg nativa. Para o tratamento com a alcalase, isolado ou associado à TG, não foram identificados fragmentos correspondentes aos epítopos após digestão gastrointestinal das amostras. Os resultados obtidos indicaram que a hidrólise, principalmente com alcalase, associada ou não à polimerização com TG, foi capaz de reduzir a antigenicidade da ß-Lg, mostrando-se uma alternativa para a produção de alimentos hipoalergênicos / Abstract: Heat treatment, high pressure and enzymatic hydrolysis have been studied aiming at obtaining products with low allergenic potential since they can alter antigenic determinants (epitopes) in the protein. The transglutaminase (TG), an enzyme that catalyzes inter or intramolecular cross-link in different proteins has also been used to reduce the protein antigenicity. The association of enzymatic hydrolysis and polymerization by TG is another strategy for reducing the antigenicity of food proteins, promising that needs further research. Therefore, the present study aimed to obtain and characterize the ß-Lg polymerized by TG before or after enzymatic hydrolysis with the proteases alcalase, neutrase or bromelain and evaluate the effect of these processes on the protein antigenic response. The optimum conditions for hydrolysis of ß-Lg, obtained with the three different enzymes, were defined using a central composite rotatable design (CCRD), where the independent variables were protein concentration (2.2% -7.8 w / v) and enzyme: substrate ratio (E:S), 6.9 to 28 U g-1 protein, and the dependent variable (response) was the degree of hydrolysis (DH) determined by the pH-stat method. The hydrolysis condition defined by CCRD was 3% of protein (w/v) and E:S ratio 25 U g-1. The experimental conditions were: (1) hydrolysis of ß-Lg with the three enzymes used separately, followed by polymerization by TG (10 or 25 U g-1) or (2) polymerization of ß-Lg (7% w/v) by TG (10U g TG-1) after heat-treatment (80 °C/60 min) or in presence of reducing agent Cys (0.1 mol L-1), followed by hydrolysis. The samples were characterized by SDS-PAGE/tricine, reverse phase high-performance liquid chromatography (RP-HPLC), liquid chromatography coupled to mass spectrometry (HPLC-MS) and by immunochemical assays (ELISA and Imunoblote). The highest DH of the ß-Lg was obtained with alcalase (12.6%), while with neutrase or bromelain a DH of 4% approximately was achieved. The electrophoresis profiles of ß-Lg polymerized after heat treatment (ß-Lg TT TG) or in the presence of Cys (ß-Lg Cys TG) showed bands with high molecular mass (MM). On the other hand, the post-hydrolysis polymerization, analyzed by SDS-PAGE and RP-HPLC, resulted in no increase in the MM of the hydrolysates. The highest concentration of the cross-link, by formation of the isopeptide bound e-(?-Gln) Lys, was found in the sample polymerized after hydrolysis with alcalase, followed by the sample ß-Lg Cys TG. The polymerized pre or pos hydrolysis with neutrase or with bromelain showed residual ß-Lg, observed in electrophoretic and chromatographic profiles, and for hydrolysates with neutrase, the band corresponding to ß-Lg showed higher residual intensity. Alcalase was the enzyme which hydrolysed more efficiently both untreated and polymerized ß-Lg. Using neutrase or bromelain to hydrolyse polymerized ß-Lg, a residual ß-Lg (18.3 kDa) was observed in the electrophoretic and chromatographic profiles. The avaluation of antigenicity showed that hydrolysis treatment used alone, especially with alcalase or bromelain, or the combination of this process with TG was capable to reduce significantly the antigenic response of ß-Lg. The ß-Lg hydrolysed with neutrase showed antigen-antibody reaction only in the region corresponding to the ß-Lg monomer, and this reaction was less intense after the association of hydrolysis with neutrase and polymerization by TG. The samples were submitted to in vitro digestion and then analyzed by mass spectrometry (MS / MS) to identification of linear epitopes in the protein. It was verified that the polymerized samples (ß-Lg TT TG or ß-Lg Cys TG) as well as those polymerized before or after hydrolysis with bromelain, retained some fragments corresponding to the epitopes, although to a lesser extent when compared to the epitopes identified in the untreated ß-Lg. Interestingly that for the treatment with alcalase, associated or not with the TG, no epitopes were identified after gastrointestinal digestion. These results indicated that the hydrolysis, especially with alcalase, and the association of hydrolysis with polymerization, were capable to reduce the ß-Lg antigenicity and could be an alternative for elaboration of hypoallergenic products / Doutorado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Doutor em Alimentos e Nutrição

Indiana University-Purdue University Indianapolis (IUPUI) / The general aim of this study was to investigate the influence of the localized irradiance beam profiles from multiple light-emitting-diode (LED) light-curing units (LCUs) on the polymerization pattern within a resin-matrix composite (RMC). Irradiance beam profiles were generated from one quartz-tungsten-halogen and various single and multiple emission peak LED LCUs using a camera-based beam profiler system combined with LCU power measurements obtained using an integrating sphere/spectrometer assembly. The influence of distance on irradiance, radiant exposure (RE) and degree of conversion (DC) on the top and bottom surfaces of a RMC increment, using various LCUs, at two clinically relevant distances was investigated. Molar absorptivity of the photoinitiators present in the nano-hybrid RMC (Tetric EvoCeram bleaching shade-XL) assessed was using UV-spectrophotometry. The correlation among irradiance, RE and DC was explored. A mapping approach was used to investigate DC, microhardness and cross-link density (CLD) within 5×5×2 mm specimens at various depths; top, 0.5, 0.7, 0.9, 1.1, 1.3,1.5 mm and bottom. The localized irradiance correlation with its corresponding DC, microhardness and CLD was explored, and localized DC correlation with microhardness was assessed. The DC was measured using micro-Raman spectroscopy, and CLD was assessed by an ethanol-softening method (%KHN reduction) using an automated microhardness tester. Molar absorptivity of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide was 20-fold higher than camphorquinone. Non-uniform LCU beam profiles caused localized polymerization discrepancies that were significant at specific depths and points within the specimens with respect to DC, microhardness and CLD, which did not follow a specific pattern regardless of the LCU or curing distance assessed. A moderate correlation was displayed among irradiance, RE and DC. The localized irradiance from the LCUs was weakly correlated with the corresponding DC, microhardness and CLD on the top surface of a RMC at both curing distances. The localized microhardness was moderately correlated with DC. In conclusion, polymerization within the RMC investigated was non-uniform and did not reflect the LCU irradiance pattern at the area assessed. Also, a mapping approach within the specimens provided a detailed polymerization pattern assessment occurring within a RMC increment. Therefore, the LCUs explored may potentially increase the risk of RMC fracture.

Microfluidics refers to manipulation, precise control, and behavior of fluids at the micro and nanoliter scales. It has entered the realm of science as a way to precisely measure or mix small amounts of fluid to perform highly controlled reactions. Glass and polydimethylsiloxane (PDMS) are common materials used to create microfluidic devices; however, glass is difficult to process and PDMS is relatively hydrophobic. In this study, SU-8, an epoxy based (negative) photoresist was used to create various electrokinetic microfluidic chips. SU-8 is commonly used in microelectromechanical design. Spin coating of various SU-8 formulations allows for 1 μm to 100 μm thick layers with aspect ratios reportedly as high as 50:1. Case studies were performed to understand the curing/crosslinking process of SU-8 by differential scanning calorimetry. Supplier (MicroChem) recommended parameters were then altered to allow for adequate development of microfluidic channels, while maintaining enough molecular mobility to subsequently bond the SU-8 to a secondary substrate. Three SU-8 layers were used to create fully (SU-8) enclosed microfluidic channels. An (1) SU-8 2050 fully cured base layer was used as a platform on silicon to build from, (2) an SU-8 2050 partially cured layer for developing microfluidic channels , and (3) an SU-8 2007 uncured layer for bonding a secondary substrate to enclose the microfluidic channels. Bond quality was verified by optical and scanning electron microscopy, which resulted in a nearly 100% bond with little to no reflow of SU-8 into channels. Working pressures (ΔP across the capillary) of 15.57 lb/in2 (max detection) were obtained with no fluid leaks. Electroosmotic flow and steaming potential measurements failed. Electrophoretic behavior of glass particles was observed and particle velocities were compared by the application of 200 volts and 300 volts, across a channel length of 2 cm. Particle velocities obtained ranged from 100 μm/s to 1500 μm/s.

Obesity is a worldwide epidemic increasing at an alarming rate among youth who are facing similar health problems as adults. Sleep Apnea Syndrome (SAS) is an underdiagnosed comorbidity of obesity, characterized by repetitive nocturnal interruptions in breathing. Obesity is associated with delayed skeletal maturation in overweight youth, but mechanisms contributing to this problem are unclear. Obesity and SAS both have been shown to disrupt regulatory hormones and cytokines that influence bone accretion during adolescence. PURPOSE: The purpose of this study was to assess the combined effects of excess body weight and SAS on bone mineral density (BMD) and content (BMC), bone turnover, and on the regulatory hormones leptin and IGF-1 known to potentially influence bone accretion during adolescence. METHODS: Men aged 18-28 years were assigned to groups as follows: normal weight controls (CON: AHI <3, n=8); overweight without SAS (OWT: BMI < 26 kg/m2 and AHI <3, n=9); and overweight with SAS (SAS: BMI >26 kg/m2 and AHI >5, n=8). The apnea/hypopnea index (AHI) expresses the score for disrupted nighttime breathing events/hr and was obtained in this study with results from a home sleep screening test. Health history and Epworth Sleepiness Scale (ESS) questionnaires also were administered. Bone mineral parameters and body composition variables were measured with dual-energy X-ray absorptiometry. Serum osteocalcin, leptin, IGF-1, and NTx-1 were measured, respectively, by radioimmunoassay and enzyme-linked immunoabsorbent assay. RESULTS: Fat-free mass, intra-abdominal fat, and fat mass were higher in the SAS and OWT groups (p<0.03). ESS scores revealed that SAS individuals were sleepier than CON and OWT groups (p<0.009). Total body and site-specific BMD and BMC values (lumbar spine, hip, and forearm) were similar between groups and did not relate to the estimated AHI score. Serum OC and NTx-1 did not differ between groups. Leptin levels were 30% higher in OWT and SAS than in the CON group (p<0.02), but did not correlate with the AHI score. Across all subjects (n=25), only lumbar spine BMC (p<0.005) was correlated to AHI (r=-.52; p<0.01). The preponderance of this relationship between AHI and lumbar spine BMC was attributable to the close inverse association of these two variables within the SAS group (r = -.81; p<0.001). CONCLUSION: The effects of SAS were not influenced by the amount of whole-body, intra-abdominal adiposity or lean body mass. Neither leptin nor IGF-1 predicted bone status across all groups. Daytime fatigue and sleepiness, a cardinal symptom of SAS, combined with overweight may contribute to lower lumbar BMC by chronically reducing weight-bearing physical activity and thereby reduce exposure time for mechanical loading of the spine in affected individuals. Further research is needed to explore the biochemical, physiological, and apparently the physical activity implications of SAS on skeletal status and turnover. / Master of Science

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2017-03-14T15:42:14Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação Graziella Pinheiro Bruni.pdf: 2435737 bytes, checksum: dd5dfba33efd7d9048f7888720783b4a (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-03-17T21:44:15Z (GMT) No. of bitstreams: 2 Dissertação Graziella Pinheiro Bruni.pdf: 2435737 bytes, checksum: dd5dfba33efd7d9048f7888720783b4a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-03-17T21:44:15Z (GMT). No. of bitstreams: 2 Dissertação Graziella Pinheiro Bruni.pdf: 2435737 bytes, checksum: dd5dfba33efd7d9048f7888720783b4a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-11-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A associação entre polímeros naturais e sintéticos para formação de biocompósitos tem sido estudada. A mistura do amido com o poli (óxido de etileno) (PEO) para a formação de biocompósitos é interessante, pois o PEO é biodegradável, apresenta alta viscosidade e biocompatibilidade com matrizes orgânicas. Além disso, o PEO apresenta uma estrutura semicristalina que pode influenciar nas propriedades dos biocompositos. A interação do amido com PEO pode ser influenciada pela estrutura molecular do amido. Com isso, objetivou-se com o presente trabalho desenvolver filmes biocompósitos à base de amidos de trigo nativo, fosfatado ou intercruzado com a adição do PEO. O amido de trigo foi modificado por fosfatação e por ligação cruzada. Os amidos foram avaliados quanto ao teor de fósforo, teor de amilose, poder de intumescimento, solubilidade em água, propriedades térmicas, propriedades de pasta, cristalinidade e morfologia. Os filmes foram elaborados com amido nativo, fosfatado ou de ligação cruzada, e com adição de PEO. Os filmes foram avaliados quanto à morfologia, solubilidade em água, permeabilidade ao vapor de água (PVA), propriedades mecânicas, parâmetros de cor (luminosidade e opacidade), cristalinidade, rugosidade e higroscopicidade. O amido fosfatado, em relação aos demais amidos, apresentou maior teor de fósforo, teor de amilose e maior poder de intumescimento e solubilidade em água. Os filmes, independentemente do tipo de amido, com a adição de PEO quando comparados aos filmes de amidos sem PEO, apresentaram morfologia descontínua, foram mais cristalinos e rugosos e menos hidrofílicos. Os filmes biocompósitos apresentaram características adequadas para aplicação em embalagens flexíveis. / The association between natural and synthetic polymers for the formation of biocomposites has been studied. The mixture of starch with poly (ethylene oxide) (PEO) for the formation of biocomposites is interesting, since the PEO is biodegradable, has high viscosity and biocompatibility with organic matrices. In addition, PEO has a semicrystalline structure that may influence the properties of the biocomposites. The interaction of the starch with PEO can be influenced by the molecular structure of the starch. The aim of this work was to develop biocomposite films based on native wheat starches, phosphated or crosslinked with the addition of PEO. The wheat starch was modified by phosphating and crosslinking. Starches were evaluated for phosphorus content, amylose content, swelling power, water solubility, thermal properties, past properties, crystallinity and morphology. The films were prepared with native, phosphate or crosslinked starch, and with addition of PEO. The films were evaluated for morphology, water solubility, water vapor permeability (WVP), mechanical properties, color parameters (luminosity and opacity), crystallinity, roughness and hygroscopicity. The phosphate starch, in relation to the other starches, presented higher phosphorus content, amylose content, swelling power and water solubility. The films, regardless of the type of starch, with the addition of PEO when compared to the starch films without PEO presented discontinuous morphology, were more crystalline and rough and less hydrophilic. The biocomposite films presented characteristics for possible use in flexible packages.