A novel method for DNA delivery into bacteria using cationic copolymers

Amphiphilic copolymers have a wide variety of medical and biotechnological applications, including DNA transfection in eukaryotic cells. Still, no polymer-primed transfection of prokaryotic cells has been described. The reversible addition-fragmentation chain transfer (RAFT) polymer synthesis technique and the reversible deactivation radical polymerization variants allow the design of polymers with well-controlled molar mass, morphology, and hydrophilicity/hydrophobicity ratios. RAFT was used to synthesize two amphiphilic copolymers containing different ratios of the amphiphilic poly[2-(dimethyl-amino) ethyl methacrylate] and the hydrophobic poly [methyl methacrylate]. These copolymers bound to pUC-19 DNA and successfully transfected non-competent Escherichia coli DH5α, with transformation efficiency in the range of 103 colony-forming units per µg of plasmid DNA. These results demonstrate prokaryote transformation using polymers with controlled amphiphilic/hydrophobic ratios.

Interfacial properties and micellization of triblock poly(ethylene glycol)-poly(-caprolactone)-polyethyleneimine copolymers

This study aimed to explore the link between block copolymers' interfacial properties and nanoscale carrier formation and found out the influence of length ratio on these characters to optimize drug delivery system. A library of diblock copolymers of PEG-PCL and triblock copolymers with additional PEI (PEG-PCL-PEI) were synthesized. Subsequently, a systematic isothermal investigation was performed to explore molecular arrangements of copolymers at air/water interface. Then, structural properties and drug encapsulation in self-assembly were investigated with DLS, SLS and TEM. We found the additional hydrogen bond in the PEG-PCL-PEI contributes to film stability upon the hydrophobic interaction compared with PEG-PCL. PEG-PCL-PEI assemble into smaller micelle-like (such as PEG-PCL4006-PEI) or particle-like structure (such as PEG-PCL8636-PEI) determined by their hydrophilic and hydrophobic block ratio. The distinct structural architectures of copolymer are consistent between interface and self-assembly. Despite the disparity of constituent ratio, we discovered the arrangement of both chains guarantees balanced hydrophilic-hydrophobic ratio in self-assembly to form stable construction. Meanwhile, the structural differences were found to have significant influence on model drugs incorporation including docetaxel and siRNA. Taken together, these findings indicate the correlation between molecular arrangement and self-assembly and inspire us to tune block compositions to achieve desired nanostructure and drug loading.

Desarrollo de vectores génicos basados en polímeros sintéticos: PEI y PDMAEMA / Development of genetic vectors based on synthetic polymers: PEI and PDMAEMA

RESUMEN En años recientes hubo un auge del uso de terapias génicas para el tratamiento de enfermedades de gran incidencia, como el cáncer. Generalmente, estas se basan en la liberación de material genético como plásmidos, en el núcleo celular, con lo cual se corrige una función o se induce la producción de proteínas deficientes a nivel fisiológico. Para llevar a cabo la terapia génica se requiere de vectores capaces de encapsular el material genético y garantizar su entrega en el núcleo celular. Los polímeros catiónicos sintéticos han llamado la atención como vectores, debido a su capacidad de condensar ácidos nucleicos para formar partículas que los protegen de la degradación enzimática y facilitan su captación celular. La polietilenimina y el polimetacrilato de N, N-dimetilaminoetilo son los polímeros catiónicos más eficaces para la administración génica. Sin embargo, estos requieren modificaciones químicas específicas para eliminar o disminuir algunas limitaciones tales como su alta citotoxicidad y baja biodegradabilidad. En este artículo se analizan algunas de estas modificaciones, enfocándose en avances recientes en el desarrollo de copolímeros anfifílicos como precursores de nanopartículas usadas como vectores génicos.

SUMMARY During recent years, the use of genetic therapies has taken relevance in the treatment of high-incidence diseases such as cancer. Usually, they are based on the release of genetic material, as plasmids, into the cell nucleus, which corrects a function or induces the production of a deficient protein at the physiological level. To carry out gene therapy, vectors capable of encapsulating the genetic material and guaranteeing its delivery in the target cell nucleus are required. Synthetic cationic polymers have attracted great attention as vectors due to their ability to condense nucleic acids to form particles that protect them from enzymatic degradation and facilitate their cellular uptake. Polyethylenimine and poly (N, N-dimethylaminoethyl methacrylate) are the most effective cationic polymers for gene delivery. However, these polymers require specific chemical modifications to either avoid or diminish their high cytotoxicity and low biodegradability. This review analyzes some of these modifications, focusing on recent advances in the development of amphiphilic copolymers as precursors of nanoparticles used as gene vectors.

Comparison of ostene and bone wax on bone healing: a comparative experimental study in rabbits

Introduction: Ostene is a new synthetic bone hemostatic wax-like inert and biocompatible material that dissolves within two days after application. bone wax is a well- known topical hemostatic agent, easy to use, and its application is very simple. wound healing is a complex biological process; bone is a dynamic tissue that is continuously resorbed, renewed, and remodeled. materials and methods: twenty domestic rabbits were divided into four groups (day 1, day 3, day 7, and day 14). each rabbit was anaesthetized and three holes were drilled in the mandible: one was filled with Ostene, another with bone wax, and the other was left unfilled as control. sites of intervention were assessed by histopathology. results and Discussion: Ostene and bone wax showed osteoinductive property in bone healing with no inflammatory reaction. our study revealed new bone formation within 14 days in Ostene group. after histopathological analysis and scoring was finished, analysis by SPSS 14 software showed a significant difference between the use of Ostene and bone wax. conclusion: Ostene showed superiority over bone wax in bone healing, and it can be used in the same way as bone wax with no interference with bone healing and osteogenesis. Ostene has no side effects following application.

Desenvolvimento e caracterização de polimerossomos para veiculação de L-asparaginase / Development and characterization of polymersomes for the release of L-asparaginase

A enzima L-Asparaginase (ASNase) é um biofámaco utilizado no tratamento da leucemia linfoblástica aguda, no entanto, a evolução da produção da ASNase como um medicamento desde o final da década de 1970 resultou em apenas quatro alternativas disponíveis no mercado farmacêutico, com relatos de graves reações imunogênicas e toxicidade. Desse modo, a nanotecnologia é uma plataforma que pode ser explorada para administração dessa enzima diminuindo a exposição da mesma a proteases e aumentando a sua meia-vida aparente. Os polimerossomos (PL) são opções que pela nanoestrutura vesicular poderiam encapsular a ASNase em seu core aquoso e pela presença de uma membrana polimérica, são mais robustos que os lipossomos. Assim, neste trabalho objetivou-se desenvolver PL para encapsulação da ASNase como uma alternativa às formulações deste biofármaco existentes. Foram desenvolvidos PL de PEG-PLA, PMPC-PDPA, PEG-PDPA e Pluronic® L-21. Foram estudados fatores relacionados à composição dos copolímeros (fração hidrofílica, responsividade a fatores externos tais como pH e temperatura) e métodos de elaboração (hidratação do filme polimérico, troca de pH e temperatura) bem como foi feita a caracterização dos PL obtidos (tamanho, índice de polidispersão, espessura de membrana, formação de excessivo bulk polimérico, obtenção de micelas). Também foi feito um planejamento racional para encapsulação da ASNase (hidratação direta do filme polimérico e encapsulação por eletroporação, autoagregação com encapsulação por troca de pH ou de temperatura). Para os PL preparados com PEG-PLA, a extrusão resultou em distribuição de tamanhos mais estreitos correspondentes aos valores de PDI de 0,345, 0,144 e 0,081 para PEG45-PLA69, PEG114-PLA153 e PEG114-PLA180, respectivamente. Foi demonstrado que copolímeros com menor fração hidrofóbica resultam em maior eficiência de encapsulação para proteínas, já que possuem volumes aquosos maiores. Com o PMPC25-PDPA72 foi possível encapsular em média três unidades de ASNase por vesículas através da eletroporação ou troca de pH, sendo que no primeiro método houve formação de túbulos e no último método as micelas não foram completamente removidas. Para PEG100-PDPA80, grandes agregados permaneceram após a purificação levando a um PDI alto, mas não foi observada a formação de túbulos, já a troca de pH para este copolímero resultou em maior perda de copolímeros como bulk polimérico precipitado. Para o copolimero tribloco Pluronic® L-121, foi observado que as vesículas eram estáveis durante uma semana à temperatura ambiente, contrariando o que era descrito na literatura. Nesses sistemas, quando preparados por hidratação do filme, a encapsulação da ASNase foi realizada por eletroporação mas a proteína não foi detectada dentro das vesículas. Atribuímos a não-encapsulação à organização da bicamada Pluronic® L-121 sem conformação definida das cadeias poliméricas, dificultando a reorganização do bloco hidrofílico na porção interna do poro durante eletroporação. Por troca de temperatura, cerca de 5 % de ASNase foi encapsulada e o método resultou em total recuperação da atividade da enzima. Desse modo foram obtidos diferentes PL com diferentes características nanoestruturais de acordo com os copolímeros utilizados para carreamento da ASNase

The enzyme L-Asparaginase (ASNase) is a biopharmaceutical used in the treatment of acute lymphoblastic leukemia, still the industrial production of ASNase as a marketable drug since the late 1970s has resulted in only four alternatives available in the pharmaceutical market, with reports of severe immunogenic reactions and toxicity. In this sense, nanotechnology is a platform that can be exploited to administer this enzyme by decreasing its exposure to proteases and increasing its apparent half-life. Polymerosomes (PL) are interesting routes which by its intrinsically vesicular nanostructure could encapsulate the ASNase in its aqueous core and by the presence of a polymeric membrane, being more robust than the liposomes. Thus, in this work it was intended to develop PL for ASNase encapsulation as an alternative to existing formulations of this biopharmaceutical. PL of PEG-PLA, PMPC-PDPA, PEG-PDPA and Pluronic® L-21 were developed. It was studied the copolymers composition (i.e. hydrophilic fraction, responsiveness to external factors such as pH and temperature), PL design (i.e. polymer film hydration, pH change and temperature) and PL characterization (i.e. size, polydispersity index - PDI, membrane thickness, formation of excessive polymer bulk, micelles production). A suitable experimental planning for ASNase encapsulation (i.e. direct hydration of the polymeric film and encapsulation by electroporation, self-aggregation with encapsulation by pH or temperature change) was also performed. For the PL prepared with PEG-PLA, the extrusion resulted in narrower size distribution corresponding to the PDI values of 0.345, 0.144 and 0.081 for PEG45-PLA69, PEG114-PLA153 and PEG114-PLA180, respectively. It has been shown that copolymers with lower hydrophobic fraction result in higher encapsulation efficiency for proteins, since they have larger aqueous volumes. With PMPC25-PDPA72 PL, it was possible to encapsulate three units of ASNase per vesicles through electroporation or pH change. In the first method, tubules were formed and in the latter one the micelles were not completely removed. For PEO100-PDPA80 PL, large aggregates remained after purification leading to a high PDI value, nevertheless no tubule formation was observed, since the pH change for this copolymer resulted in greater loss of copolymers as a precipitated polymer bulk. For the Pluronic® L-121 triblock copolymer PL, it was observed that the vesicles were stable for one week at room temperature, contrary to what was described in the literature. These PLs were prepared by film hydration method and ASNase encapsulation was performed by electroporation, nonetheless the protein was not detected within the vesicles. It is attributed the non-encapsulation to the organization of the Pluronic® L-121 bilayer without defined conformation of the polymer chains, making it difficult to reorganize the hydrophilic block in the internal portion of the pore during electroporation. By temperature change, about 5% of ASNase was encapsulated and the method resulted in complete recovery of enzyme activity. In conclusion, several PLs with a vast range of differential nanostructural characteristics were obtained according to the copolymers used for ASNase loading

Thermoresponsive and Biodegradable Amphiphilic Block Copolymers with Pendant Functional Groups

BACKGROUND: To develop the biodegradability and thermoresponsive hydrogel, in this work we designed a pendant-functionalized, thermoresponsive, amphiphilic block copolymer. METHODS: Methoxy poly(ethylene glycol) (MPEG)-b-[poly(ε-caprolactone)-ran-poly(ε-caprolactone-3-one)-ran-polylactic acid] (MCL) and (MPEG-b-[PCL-ran-POD-ran-PLA]) [MCL-(CO)] block copolymers were prepared by ringopening polymerization of ε-caprolactone, OD and lactide monomers. The subsequent derivatization of MCL-(CO) provided MPEG-b-[PCL-ran-poly(ε-caprolactone-3-COOH)-ran-PLA] [MCL-(COOH)] with COOH pendant groups and MPEG-b-[PCL-ran-poly(ε-caprolactone-3-NH2)-ran-PLA] [MCL-(NH2)] with NH2 pendant groups. RESULTS: The measured segment ratios of MCL-(CO), MCL-(COOH), and MCL-(NH2) agreed well with the target ratios. The abundances of the COOH and NH2 groups in the MCL-(COOH) and MCL-(NH2) copolymers were determined by 1H- and 13C-nuclear magnetic resonance spectroscopy, and agreed well with the target abundances. MCL-(CO), MCL-(COOH), and MCL-(NH2) formed homogeneous, white, opaque emulsions at room temperature. Rheological analysis of the block copolymer suspensions indicated a solution-to-hydrogel phase transition as a function of temperature. The solution-to-hydrogel phase transitions and the biodegradation of MCL-(CO), MCL-(COOH), and MCL-(NH2) were affected by varying the type (ketone, COOH, or NH2) and abundance of the pendant groups. CONCLUSION: MCL-(CO), MCL-(COOH), and MCL-(NH2) with ketone, COOH, and NH2 pendant groups showed solution-to-hydrogel phase transitions and biodegradation behaviors that depended on both the type and number of pendant groups.

Block Copolymer Self-assembled and Cross-linked Nanoassemblies for Combination Delivery of Iron Oxide and Doxorubicin.

We describe the development of nanoscale polymer drug carriers for the combinational delivery of an anticancer drug (doxorubicin: DOX) along with super paramagnetic iron oxide nanoparticles (IONPs). The drug molecules were electrostatically loaded into both block copolymer self-assembled nanoassemblies (SNAs) and cross-linked nanoassemblies (CNAs). Both nanoassemblies entrapped DOX and IONPs either individually or in tandem, maintaining sub-100 nm diameter. The IONP-loaded nanoassemblies generated heat in the presence of an alternating magnetic field (AMF). Incorporation of the drug payload, DOX, showed no adverse effects on the heating profile. Drug release from the SNAs and CNAs was accelerated as temperature increased from the normal body temperature (37°C) to a mild hyperthermic condition (40  42°C). CNAs released DOX faster than SNAs regardless of an incubation temperature. CNAs co-entrapped IONPs and DOX were more stable than SNAs in aqueous solutions for five days. These results suggest that block copolymer cross-linked nanoassemblies provide viable delivery platforms for combination delivery of inorganic molecules, anticancer drugs, and potentially other various biologically active substances.

Research progress on polymersomes as drug delivery system / 国际生物医学工程杂志

Polymersomes have attracted tremendous attention as novel drug delivery systems because of their unique and superior structure,tunable membrane properties,colloidal stability,and ability in encapsulating a broad range of both water soluble and insoluble substances.In this paper,preparation method and criteria for the formation of polymersomes,their structure and characterization as well as amphiphilic block copolymers for vesicle formation are addressed.Moreover,research progress on polymersomes as drug delivery system in the field of therapeutic and diagnostic applications are reviewed in this paper.

Potential drug delivery system: study of the association of a model nitroimidazole drug with aggregates of amphiphilic polymers on aqueous solution

This study evaluated the association of N-hexyl-2-methyl-4-nitroimidazol, a model drug, to aggregates formed by anionic polyelectrolytes on aqueous solution. The alternating copolymers of maleic anhydride and N-vinyl-2-pyrrolidone were synthesized and then modified by reaction of the anhydride groups with aliphatic amines and alcohols of varying length of the alkyl chain. The partition of the model drug between water and the hydrophobic microdomains provided by the copolymers was studied using the pseudo-phase model to determinate the distribution coefficient K S, and the standard free energy of transfer ∆µ°t. The results indicate that all copolymers assessed are potential pharmaceutical reservoirs of the model drug. Nevertheless, the solubility of N-hexyl-2-methyl-4-nitroimidazol on the polymeric solutions is independent from the length of the alkyl chain of the copolymer.

Realizou-se estudo sobre a associação da N-hexil-2-metil-4-nitroimidazol, fármaco modelo, aos agregados formados por polieletrólitos aniônicos em solução aquosa. Os copolímeros alternados de anidrido maléico e N-vinil-2-pirrolidona foram sintetizados e, em seguida, modificados pela reação dos grupos de anidrido com aminas e álcoois alifáticos de duração variável da cadeia alquílica. A partição do fármaco modelo entre a água e os microdomínios hidrofóbicos fornecido pelos copolímeros foi estudada usando o modelo de pseudo-fase, a fim de determinar a distribuição do coeficiente K S e a energia livre padrão de transferência ∆µ°t. Os resultados indicam que todos os copolímeros avaliados são potenciais reservatórios farmacêuticos do fármaco. No entanto, a solubilidade do N-hexil-2-metil-4-nitroimidazol sobre as soluções poliméricas é independente do comprimento da cadeia alquílica do copolímero.

Advances in encapsulation of siRNA with PEI and its copolymers for cancer gene therapy / 国际生物医学工程杂志

The gene silence induced by small interfering RNA (siR N A) provides a powerful tool for gene therapy of neoplasm. However, safe and efficient delivery of exogenous siRNA is still the key issue for clinical application. Polyethyenimines ( PEI ) and its copolymers can encapsulate siRNA into complex in the formation of nanoparticle wherein the stability and activity of siRNA are closely related to the structure and molecular weight of PEI, N/P ratio, and the composition of copolymers.The siRNA-encapsulated nanoparticles can effectively inhibit the proliferation of tumor cell not only in vitro, but also in vivo by administration via intratumoral,intraperitoneal or venous injections.

Study on injectable paclitaxel loaded PCL/PEG/PCL thermosensitive hydrogels / 国际生物医学工程杂志

Objective To construct an injectable controlled delivery system of paclitaxel based on thermosensitive PCL1250-PEG1500-PCL1250 hydrogels. Methods A thermosensitive PCL1250-PEG1500-PCL1250 triblock copolymer was synthesized by ring-opening polymerization of e-CL using PEG (Mw=l 500) as the initiator and Sn(Oct)2 as the catalyst. The synthesized PCL1250-PEG1500-PCL1250 copolymers were characterized for their composition,structure, and molecular weight via 1H NMR and GPC techniques. A series of Paclitaxel loaded hydrogels with various predesigned hydrogel concentrations and initial drug loadings were prepared to investigate their gelation ability, in vitro drug release behavior and in vivo biodegradability. Results The results calculated from 1H NMR and GPC indicated that EG/CL ratio(1.55) was consistent with the initial feed ratio(1.6), which offered a strong proof to their composition and molecular structure. The thermosensitive PCL1250-PEG1500-PCL1250 hydrogels exhibited a desirable sol-gel transition ability within the concentration range of 15%-30%. The in vitro release rate of paclitaxel from the paclitaxel/PCL1250-PEG1500-PCL1250 hydrogels was controllable by altering the hydrogel concentrations and initial drug loadings. The PCL1250-PEG1500-PCL1250 hydrogels showed a good in situ gelation ability after subcutaneously injected into mouse back. The in situ formed hydrogels gradually degradated with time and almost disappeared after 45 days in vivo. Conclusion Both the controllable drug release behavior and promising biodegradability of this new thermosensitive PCL1250-PEG1500-PCL1250 hydrogels paved a way to develop a novel delivery system for paclitaxel.

Uso de la regeneración ósea guiada (rog) con membranas biodegradables de co-polímeros en cirugía bucal para reparar defectos óseos: estudio clínico de 30 meses de seguimiento postquirúrgico

La regeneración ósea guiada (ROG) es frecuentemente usada para tratar defectos óseos pero muchas veces el tipo de membrana usada se degrada antes de que ocurra la adecuada cicatrización ósea y se introduce tejido blando en la zona a regenerar. El objetivo de éste estudio es evaluar la eficacia de usar el sistema de membranas y tachuelas biodegradables de co-polímeros en pacientes con defectos óseos o que necesiten levantamiento de membrana sinusal con un periódico control clínico y radiográfico. Este estudio fue realizado en 15 pacientes que tenían defectos óseos o necesitaban levantamiento de membrana sinusal, con un rango de edad entre 19 y 49 años con un promedio de 34 años de edad. 8 pacientes fueron femeninos y 7 masculinos. Se usó relleno óseo con las membranas y tachuelas biodegradables de co-polímeros en todos los casos, 7 de los casos fueron levantamiento de membrana sinusal y los otros 8 se trataron de defectos óseos. Se les realizó un seguimiento clínico y radiográfico cada 3 y 6 meses hasta 30 meses después del día de la cirugía entre los años 2005 y 2007, realizándose un análisis longitudinal. Se encontró que a 5 pacientes se les expuso la membrana, uno de ellos se mantuvo con enjuagues de clorhexidina hasta que cicatrizó por segunda intención, en 2 de los pacientes se les recortó y moldeó el borde expuesto y los otros 2 casos se tuvo que retirar la membrana y tachuelas por completo. Los 10 pacientes restantes cicatrizaron adecuadamente y no tuvieron ningún tipo de exposición, siendo el porcentaje de éxito al utilizar éste nuevo sistema de membranas y tachuelas biodegradables de co-polímeros del 66,7%. Se destaca que éste sistema de membranas y tachuelas biodegradables de co-polímeros no necesita ser retirado en una 2da cirugía. Debido al buen control postquirúrgico se pudo manejar de inmediato los casos donde hubo exposición de la membrana y sólo fracasaron 2 de 15. Se observó una adecuada cicatrización ósea tanto clínica ...

Guided bone regeneration (GBR) is frequently used to treat bone defects, however, most of the membranes degrade before bone healing has occurred permitting soft tissue invasion into the desired bone chamber. The aim of this clinical trail is to evaluate the efficacy of using a biodegradable co-polymers membrane and tacks system in patients with bone defects or need of maxillary sinus lift for implant placement with a long term clinical and radiographically follow up. All patients included in this study had the necessity of guided bone regeneration. 15 patients consisted of bone defects or the need of maxillary sinus lifting, with an age range of 19 to 49 years of age with an average of 34 years old. There were 8 females and 7 males. In all cases, we used biodegradable co-polymers membrane and tacks system that gets soft when applied but becomes rigid in-situ after approximately 15 minutes allowing the new bone cicatrization because it becomes a barrier for the bone grafting material, 7 patients underwent surgery for maxillary sinus lift and the other 8 for bone defects. Patients were followed clinical and radiographically during 3 to 6 months intervals up to 30 months between 2005 - 2007. A longitudinal study was performed by checking the patients clinical and radiographically during a continuously period of time up to 30 months postoperatively. 5 patients had partial membrane exposure, one of them was kept in clorhexidine mouth rinses and irrigation until secondary healing was accomplished. 2 patients were treated by cutting and trimming the membrane edges in order to get full mucosa coverage and it was obtained in 2 weeks after this procedure. In 2 cases the flap open totally and we had to remove the membrane. The rest 10 of the 15 patients healed uneventfully. The percentage of success using the biodegradable co-polymers membrane and tacks system was 66,7% . This biodegradable co-polymers membrane and tacks system does not require ...

Radiation induced graft copolymerization of acrylamide onto poly (3-hydroxybutyrate) / Copolimerización por injerto radioinducido de acrilamida en el poli (3-hidroxibutirato)

The graft copolymer poly (3-hydroxybutyrate)-g- polyacrylamide[P (HB-g-AAm)] was synthesized by radiation induced graft copolymerization of acrylamide onto poly (3-hydroxybutyrate). The study was conducted by the simultaneous irradiation method. The structure of [P (HB-g-AAm)] was identified by Fourier Transform Infrared (FTIR) spectroscopy. Thermal behavior of the graft copolymer was also studied by Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). According to the results, FTIR studies showed new signals (stretching-N-H) as an important evidence of grafting. The grafting degree, determined by ATG, was 10% and changes in thermodynamic parameter obtained from the DSC were detected. Such changes show a decrease in crystallinity and an increase in the glass transition temperature. These results demonstrate that the gamma radiation-induced graft copolymerization reaction of acrylamide onto PHB was successively achieved.

En el trabajo se realizó la síntesis del copolímero por injerto poli (3-hidroxibutirato)-g- poliacrilamida [P (HB-g-AAm)] por copolimerización de injerto radioinducido del monómero acrilamidaen el PHB. El estudio se llevó a cabo por el método de la irradiación simultánea. La estructura del copolímero se identificó por espectroscopía Infrarrojo por Transformada de Fourier (FTIR). Además, se realizó el estudio térmico del compuesto obtenido por análisis termogravimétrico (TGA) y calorimetría diferencial de barrido (DSC). De los resultados se encontraron señales (vibraciones de valencia -N-H) por FTIR que constituyen una importante evidencia de la reacción de injerto. El grado de injerto determinado por ATG fue de 10% y se detectaron cambios en los parámetros termodinámicos estudiados por DSC, que muestran una disminución de la cristalinidad y un aumento de la temperatura de transición vítrea. Los resultados demostraron la formación del copolímero por injerto inducido por radiaciones gamma.