FRLP - I+D+i - CENTROS - CITEMA - TRABAJOS DE INVESTIGACIÓN
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Item Synthesis, characterization and swelling behavior of new pH-sensitive hydrogels derived from copolymers of 2-hydroxyethyl methacrylate and 2-(diisopropylamino) ethylmethacrylate(2012) Faccia, Paula; Amalvy, JavierThe aim of this work was to synthesize and to characterize new pH-sensitive hydrogels that can be used in the controlled release of drugs, useful for dermal treatments or ophthalmology’s therapies. Copolymers containing 2-hydroxyethyl methacrylate (HEMA) with different amounts of 2-(diisopropylamino)ethyl methacrylate (DPA) (10 and 30 wt %) and different amounts of cross- linker agent, ethylene glycol dimethacrylate (EGDMA) (1 and 3 wt %) were prepared by bulk photo-polymerization. The copolymers were fully characterized by using Fourier-transform infrared (FTIR) spectra, differential scanning calorimetry, thermogravimetric anal- ysis, UV–visible spectroscopy, and measuring water content and dynamic swelling degree. The results show that modifications in the amount of DPA and/or crosslinker in the hydrogel produce variations in the thermal properties. When adding of DPA, we observed an increase in the thermal stability and decomposition temperature, as well as a change in the mechanism of decomposition. Also a decrease in the glass transition temperature was observed with regard to the value for pure pHEMA, by the addition of DPA. The water content of the hydrogels depends on the DPA content and it is inversely proportional to both the pH value and the crosslinking degree. Pure poly-HEMA films did not show important changes over the pH range studied in this work. The dynamic swelling curves show the overshooting effect associated with the incorporation of DPA, the pH of the solution, and the crosslinking density. On the other hand, no important variations in the optical properties were observed. The synthesized hydrogels are useful as a drug delivery pH-sensitive matrix.Item Synthesis and swelling behavior of pH-responsive polyurethane poly(2-(diethylamino)ethyl methacrylate) hybrid materials(2013) Pardini, Francisco; Amalvy, JavierPolyurethane (PU)/poly[2-(diethylamino)ethyl methacrylate] hybrids, having a chemical bond between the PU and acrylic moieties and with different compositions, were prepared by the dispersion polymerization of 2-(diethylamino)ethyl methacrylate (DEA) in the presence of preformed PU chains with polymerizable terminal vinyl groups. The PU dispersion was synthesized accord- ing to a prepolymer mixing process by the polyaddition of isophorone diisocyanate, poly(propylene glycol), 2-hydroxyethyl methacry- late, and dimethylol propionic acid (DMPA). Then, it was dispersed in water by the prior neutralization of the carboxylic acid groups of DMPA with triethylamine, chain-extended with ethylenediamine. The effect of the DEA content on the swelling properties (water uptake and dynamic swelling degree) at different pHs and at 37�����C was determined. The samples were also characterized by Fourier transform infrared spectroscopy and modulated differential scanning calorimetry. The experimental results indicate a higher water uptake when the DEA content was increased on the hybrid materials and a significant change in the kinetics of swelling at pH 4 com- pared to those at pH 7. The water content of the hydrogels depended on the DEA content, and it was inversely proportional to the pH value. The pure PU film did not show important changes over the pH range examined in this study. The synthesized hybrids were useful as drug-delivery, pH-sensitive matrices.Item Polyurethane Poly(2-(Diethyl Amino)Ethyl Methacrylate) blend for drug delivery applications(2015) Echeverría, María Gabriela; Pardini, Oscar; Debandi, María Valeria; François, Nora; Daraio, Marta; Amalvy, JavierA pH-sensitive blend of polyurethane (PU) and poly(2-(diethyl amino)ethyl methacrylate (PDEA) with good film-forming capacity was prepared from the corresponding aqueous dispersions. The polymer matrix was first characterized by using FTIR, DSC, water vapor transmission and water swelling capacity at different pHs. The drug release profile of films was evaluated using a vertical Franz Cell and theophylline as model drug. The water swelling degree increases from 54 to 180% when the pH of the medium is changed from 6 to 2, demonstrating the pH-responsive behavior of the film. The in-vitro release studies indicate that an anomalous transport mechanism governs the theophylline release.Item Evaluation of pH-sensitive polyurethane 2-diethylaminoethyl methacrylate hybrids potentially useful for drug delivery developments(2015) Pardini, Francisco; Faccia, Paula; Amalvy, JavierSmart sensitive polymers have been used to improve processes in drug delivery. In this article, we evaluate the behavior of polyurethane/N,N-diethylaminoethyl methacrylate hybrids (PU/DEA) as pH- responsive polymers potentially useful for drug delivery systems development, using Rhodamine 6G (Rh6G) as a model drug. A detailed pH responsive characterization was performed by swelling studies and scanning electron microscopy (SEM). Two drug loading methods on drug release-immersion and direct loading were evaluated. The interaction between Rh6G and the polymer matrix was studied by Fourier Transform Infrared (FTIR) spectroscopy and contact angle determination. The kinetic study of Rh6G release was performed at basic and acidic pH; the mechanism of drug delivery was analyzed using Ritger-Peppas' equation. We discuss about polymer's active sites and drug's distribution through the matrix in relation to both loading methods. Results showed a pH-responsive behavior and morphological changes when pH solution varied from 9.0 to 4.0. In the immersion loading method, results indicated a higher Rh6G molecule concentration at the surface as well as ionic interaction between the drug and polymer's carboxylic groups. Release studies confirmed the pH-sensitive hybrid systems' behavior and kinetic exponent values indicated different mechanism's transport types depending on loading method and polymer composition.