Diffusion of drugs in hydrogels based on (meth)acrylates, poly(alkylene glycol) (meth)acrylates and itaconic acid

The aim of this paper is to propose equations for the diffusion of drugs for investigated drug/hydrogel systems using the parameters affecting the transport of drug through poly- (2-hydroxyethylmethacrylate/itaconic acid) (P(HEMA/IA)), poly(2-hydroxyethylacrylate/ita- conic acid) (P(HEA/IA)), and poly(2-hydroxyethylmethacrylate/poly(alkyleneglycol) (meth)- acrylates) (P(HEMA/BIS)) copolymeric hydrogels. Different monomer types, as well as the variable content of some components in hydrogel composition (the amount of ionizable comonomer (IA) and different type of nonionic poly(alkyleneglycol) (meth)acrylates), ultimately defined the pore size available for drug diffusion. The hydrogels synthesized ranged from nonporous to microporous, based on the classification in accordance to the pore size, and could be classified as hydrogels that contain ionic groups and hydrogels without ionic groups. The drugs selected for this study are bronchodilators-theophylline (TPH), fenethylline hydrochloride (FE), and antibiotic cephalexin (CEX). Results of in vitro drug release tests defined the release systems based on the drug type, as well as the type of hydrogel used. The diffusion coefficient of drugs and the restriction coefficient, λ, defined as the ratio of solute to 'pore' radius (rs/rζ) that describes the ease of drug release from the gels, were used as factors that govern the release process.Cilj ove studije je da se predlože difuzione jednačine za ispitivane sisteme lek/hidrogel. Korišćeni su hidrogelovi poli(2-hidroksietilmetakrilat/itakonska kiselina) (P(HEMA/IK)), poli(2-hidroksietilakrilat/itakonska kiselina) (P(HEA/IK)) i poli-(2-hidroksietilmetakrilat/poli(alkilenglikol)-(met)akrilati) (P(HEMA/BIS)). Komponenta koja se menja u sastavu hidrogela HEMA, HEA, kao i udeo komponente sa promenljivim sadržajem (udeo jonizujućeg komonomera (IK) i tip BIS komponente) definiše veličinu pora koja je dostupna za difuziju leka. U ovoj studiji su korišćeni lekovi bronhodilatori teofilin (TPH) i fenetilin-hidrohlorid (FE), i antibiotik cefaleksin (CEX). Ovi gelovi su klasifikovani u režimu poroznosti kao neporozni i mikroporozni, sa veličinom pora u opsegu 0,18-24,9 nm. Kontrolisano otpuštanje lekova je izvedeno u in vitro uslovima u puferu pH 7,40 i na 37 °C, da bi se odredili difuzioni koeficijenti leka u hidrogelovima. Na osnovu toga su predložene jednačine difuzije leka kroz hidrogel za svaki sistem lek/hidrogel. Rezultati dobijeni fitovanjem eksperimentalnih podataka su pokazali da difuzija leka zavisi od hemijske strukture i morfologije hidrogela i parametra λ, koji predstavlja odnos prečnika leka i veličine pora. Eksponencijalna zavisnost koeficijenta restrikcije od normalizovanog koeficijenta difuzije je dobijena za sisteme TPH/P(HEMA/IA), FE/P(HEMA/ /IA), CEX/P(HEMA/BIS) i CEX/P(HEA/IA).Utvrđeno je da veliki uticaj na difuziju leka imaju interakcije koje se odigravaju između funkcionalnih grupa leka i polimerne mreže

Smart poly(2-hydroxyethyl methacrylate/itaconic acid) hydrogels for biomedical application

pH- and temperature-sensitive hydrogels, based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) copolymers, were prepared by gamma-irradiation and characterized in order to examine their potential use in biomedical applications. The influence of comonomer ratio in these smart copolymers on their morphology, mechanical and thermal properties, biocompatibility and microbe penetration capability was investigated. The mechanical properties of copolymers were investigated using the dynamic mechanical analysis (DMA), while their thermal properties and morphology were examined by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The morphology, mechanical and thermal properties of these hydrogels were found to be suitable for most requirements of biomedical applications. The in vitro study of P(HEMA/IA) biocompatibility showed no evidence of cell toxicity nor any considerable hemolytic activity. Furthermore, the microbe penetration test showed that neither Staphylococcus aureus nor Escherichia coli passed through the hydogel dressing; thus the P(HEMA/IA) dressing could be considered a good barrier against microbes. All results indicate that stimuli-responsive P(HEMA/IA) hydrogels have great potential for biomedical applications, especially for skin treatment and wound dressings. (C) 2009 Elsevier Ltd. All rights reserved

Synthesis and characterization of silver/poly(N-vinyl-2-pyrrolidone) hydrogel nanocomposite obtained by in situ radiolytic method

This work describes radiolytic synthesis of silver nanoparticles (Ag NPs) within the poly(N-vinyl-2-pyrrolidone) (PVP) hydrogel. The hydrogel matrix was obtained by gamma irradiation-induced cross-linking, while the in situ reduction of Ag(+) ions was performed using strong reducing species formed under water radiolysis. Absorption spectrum of the Ag/PVP nanocomposite confirmed the formation of Ag NPs, showing the surface plasmon band maxima at 405 nm. Ag/PVP nanocomposites were characterized by XRD and TEM analysis, accompanied with investigations of swelling and diffusion properties in the simulated body fluid at 37 degrees C, and mechanical properties in bioreactor conditions. It was shown that Ag/PVP nanocomposite exhibited higher values of equilibrium swelling degree, Youngs modulus, and molar mass between crosslinks, while lower values of the diffusion coefficient and effective crosslink density were obtained, as compared to the pure PVP. (C) 2011 Elsevier Ltd. All rights reserved

2-Hydroxyethyl Methacrylate/Gelatin/Alginate Scaffolds Reinforced with Nano TiO₂ as a Promising Curcumin Release Platform

The idea of this study was to create a new scaffolding system based on 2-hydroxyethyl methacrylate, gelatin, and alginate that contains titanium(IV) oxide nanoparticles as a platform for the controlled release of the bioactive agent curcumin. The innovative strategy to develop hybrid scaffolds was the modified porogenation method. The effect of the scaffold composition on the chemical, morphology, porosity, mechanical, hydrophilicity, swelling, degradation, biocompatibility, loading, and release features of hybrid scaffolds was evaluated. A porous structure with interconnected pores in the range of 52.33–65.76%, favorable swelling capacity, fully hydrophilic surfaces, degradability to 45% for 6 months, curcumin loading efficiency above 96%, and favorable controlled release profiles were obtained. By applying four kinetic models of release, valuable parameters were obtained for the curcumin/PHEMA/gelatin/alginate/TiO2 release platform. Cytotoxicity test results depend on the composition of the scaffolds and showed satisfactory cell growth with visible cell accumulation on the hybrid surfaces. The constructed hybrid scaffolds have suitable high-performance properties, suggesting potential for further in vivo and clinical studies