Hydrogels Based On 2-hydroxyethyl Methacrylate Research Articles

Hydrogels in Biomedicine: Granular Controlled Release Systems Based on 2-Hydroxyethyl Methacrylate Copolymers. A Review

The article analyzes and summarizes the latest achievements in the field of polymer systems for controlled release devices based on hydrogel materials. Possible directions of drug delivery are presented, including the use of granular hydrogels, which work on the principle of drug sorption − release in the body. The research on the synthesis regularities, structure, properties, and prospects for the use of granular hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and its copolymers, in particular with polyvinylpyrrolidone (PVP), as systems for the controlled release of substances, in particular, drugs, is analyzed.

Nanocellulose bio-based composites for the removal of methylene blue from water: An experimental and theoretical exploration

In this work, we synthesized new bio-composites as adsorbents to remove methylene blue (MB) from aqueous solutions. These hydrogels, based on 2-hydroxyethylmethacrylate (HEMA), were prepared by free-radical copolymerization with itaconic acid (IA) or acrylic acid (AA) monomers in combination with different amounts of cellulose nanofiber (CNF). The mass yield percent in all the synthesized materials is over 94%. The bio-composites were characterized by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM) techniques. The capacity to absorb water and to remove MB was determined through batch studies.FT-IR and TGA analysis reveals the molecular structure of the polymers and its good stability in the temperature range of 25–490 °C. In addition, highly porous morphology was observed by SEM. Bio-composites prepared with a higher percentage in mass of CNF showed a MB removal efficiency of approximately 100% for poly (2-hydroxyethylmethacrylate-co-itaconic acid) with 2% CNF (P(HEMA-co-IA)-2%CNF) and 80% for poly (2-hydroxyethylmethacrylate-co-acrylic acid) with 2% CNF (P(HEMA-co-AA)-2%CNF), where the maximum adsorption capacity was 467.51 mg g−1 for P(HEMA-co-IA)-2%CNF and 339.90 mg g−1 for P(HEMA-co-AA)-2%CNF. Furthermore, after three adsorption-desorption cycles in an acidic medium (pH 1.0), both hydrogel systems decreased their adsorption efficiency by approximately 20%. From a theoretical point of view, the most stable conformation showed that CNF and MB molecules prefer to move to different areas of the polymer network, avoiding a direct interaction. However, in the polymeric network there are energetically favourable contacts between MB, and CNF. The intermolecular interactions are predominantly dominated by weak interactions such as London dispersion and electrostatic interactions between charged groups. Molecular dynamics (MD) simulations help to identify the existence of π-π stacking interactions between aromatic rings from MB in the polymeric network. Contact interactions were characterized by the non-covalent interaction index (NCI) index.

Radiolytic synthesis of gold nanoparticles in HEMA-based hydrogels: Potentialities for imaging nanocomposites

Abstract This article reports on the radiolytic synthesis of nanocomposites containing gold nanoparticles (AuNPs) within two types of hydrogels based on 2-hydroxyethyl methacrylate (HEMA): (i) plain networks with various contents in ethylene glycol dimethacrylate (EGDMA), as a cross-linker and (ii) stimuli-responsive (SR) networks prepared from these monomers copolymerized with [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MADQUAT) to confer pH-switchable swelling. Hydrogels were prepared by photopolymerization with well-defined composition and a high degree of monomer conversion using two experimental procedures, as xerogels or in aqueous solution. Besides MADQUAT, acrylic acid (AA) or N-isopropylacrylamide have been tested as copolymers, yielding pHor temperature-sensitive hydrogels, respectively. Isothermal swelling in water was affected by monomer composition. Electron beam (EB) irradiation at doses up to 100 kGy of poly(HEMA) xerogels and water-swollen networks prepared with 0.5 wt% of EGDMA had a moderate impact on swelling characteristics and thermomechanical properties of the plain materials, whereas small amounts of extractables were formed. Poly(HEMA)-based nanocomposites containing AuNPs were successfully obtained by EB irradiation of samples swollen by aqueous solutions of Au(III). The effects of dose and cross-linking density on the formation of AuNPs were monitored by UV-visible spectroscopy. Irradiation at well-defined temperatures of the Au(III)-loaded SR hydrogels induced the formation of nanoparticles with size-dependent features, whereas the efficiency of Au(III) reduction at 10 kGy was not significantly affected by the network structure. EB-induced reduction of Au(III) in poly(HEMA) hydrogels using a lead mask to generate well-defined patterns yielded coloured and long-lasting images in the zones where the nanocomposite was formed.

Tough and Elastic α-Tricalcium Phosphate Cement Composites with Degradable PEG-Based Cross-Linker.

Dual setting cements composed of an in situ forming hydrogel and a reactive mineral phase combine high compressive strength of the cement with sufficient ductility and bending strength of the polymeric network. Previous studies were focused on the modification with non-degradable hydrogels based on 2-hydroxyethyl methacrylate (HEMA). Here, we describe the synthesis of suitable triblock degradable poly(ethylene glycol)-poly(lactide) (PEG-PLLA) cross-linker to improve the resorption capacity of such composites. A study with four different formulations was established. As reference, pure hydroxyapatite (HA) cements and composites with 40 wt% HEMA in the liquid cement phase were produced. Furthermore, HEMA was modified with 10 wt% of PEG-PLLA cross-linker or a test series containing only 25% cross-linker was chosen for composites with a fully degradable polymeric phase. Hence, we developed suitable systems with increased elasticity and 5–6 times higher toughness values in comparison to pure inorganic cement matrix. Furthermore, conversion rate from α-tricalcium phosphate (α-TCP) to HA was still about 90% for all composite formulations, whereas crystal size decreased. Based on this material development and advancement for a dual setting system, we managed to overcome the drawback of brittleness for pure calcium phosphate cements.

Synthesis, Swelling Properties and Evaluation of Genotoxicity of Hydrogels Based on (Meth)acrylates and Itaconic Acid

In this study we prepared hydrogels based on 2-hydroxyethyl methacrylate (HEMA): PHEMA homopolymer and two terpolymers of HEMA, itaconic acid (IA) and two poly(alkylene glycol) (meth) acrylates (PAGM): poly(ethylene glycol)6 acrylate (P(HEMA/IA/PAGM1)) and poly(propylene glycol)5 methacrylate (P(HEMA/IA/PAGM2)). Hydrogels were synthesized by gamma-irradiated radical polymerization and subjected to swelling measurements and genotoxicity evaluation. Swelling studies confirmed that these hydrogels deserve consideration as biomaterials due to their ability to swell in phosphate buffer but maintaining physical integrity for a prolonged contact time after equilibrium state has been reached. Comet assay showed certain genotoxic effect following cell exposure to extracts of hydrogels, which was dependent on the concentration of extracts, chemical composition of hydrogels and the degree of crosslinking. The influence of concentration on genotoxicity was the most pronounced. The synthesis of these novel HEMA-based hydrogels should be optimized so as to reduce their toxicity and enable the use in clinical practice.

PH-sensitive hydrogels based on (meth)acrylates and itaconic acid

Novel hydrogels based on 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA) and different poly (alkylene glycol) (meth)acrylates (PAGM) (P(HEMA/IA/PAGM)) were synthesized. We investigated the influence of different PAGM components, with acrylic or methacrylic acid residues in the main chain and ethylene glycol (EG) and/or propylene glycol (PG) units in pendant chains of varying length, on the nature and inherent properties of P(HEMA/IA/PAGM) copolymeric hydrogels. Swelling studies revealed pH sensitive behavior of P(HEMA/IA/PAGM) samples. Hydrogel structure and morphology were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), which confirmed their chemical structure and differences in pore size. The shear modulus values for P(HEMA/IA/PAGM) hydrogels were close to that of PHEMA, but slightly lower than the value for P(HEMA/IA). Cephalexin (CEX) drug release profiles from P(HEMA/IA/PAGM) samples showed a marked dependence on the PAGM component. The presence of IA also influenced the release rate of CEX, leading to a faster release when IA was combined with the more hydrophilic PAGM component. An in vitro assay of P(HEMA/IA/PAGM) cytotoxicity showed good cell viability. The results obtained indicate that P(HEMA/IA/PAGM) hydrogel properties were significantly dependent on the PAGM component, meaning that the type of side chains can be used to tune the characteristics of such biomaterials. These properties make P(HEMA/IA/PAGM) copolymeric hydrogels applicable in biomedical and biotechnological fields and controlled drug delivery.

Radiation synthesis, characterisation and antimicrobial application of novel copolymeric silver/poly(2-hydroxyethyl methacrylate/itaconic acid) nanocomposite hydrogels

Silver nanoparticles were fabricated via in situ reduction of silver nitrate embedded in swollen P(HEMA/IA) hydrogel, using gamma radiolysis method. Copolymeric hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA), previously synthesised by gamma radiation for wound dressing application, were used as a carrier and a stabilising agent, while ethyl alcohol was used as a free radical scavenger. The influence of different P(HEMA/IA) hydrogels and silver salt concentrations on the size and distribution of nanoparticles was investigated. The Ag/P(HEMA/IA) nanocomposites were characterised by high resolution scanning electron microscopy, energy dispersive spectroscopy, wide-angle X-ray diffraction, UV-Vis spectroscopy and swelling measurements. Escherichia coli (Gram-negative bacterium), Staphylococcus aureus (Gram-positive bacterium) and Candida albicans (fungus) were used to prove the antimicrobial properties of Ag/P(HEMA/IA) nanocomposites. The inhibition kinetics of bacteria growth was investigated by measuring the colony-forming unit. The antimicrobial effectiveness of the Ag/P(HEMA/IA) hydrogel nanocomposite was demonstrated even at small silver concentrations. P(HEMA/IA) hydrogels containing nanosilver particles was found suitable to be used as wound dressing.

Synthesis and characterization of poly(2-hydroxyethyl methacrylate/itaconic acid/poly(ethylene glycol) dimethacrylate) hydrogels

Hydrogels based on 2-hydroxyethyl methacrylate (HEMA), different poly(ethylene glycol) dimethacrylates (PEGDMA) and itaconic acid (IA) were prepared by free radical crosslinking copolymerization. The influence of different PEGDMA content and type, with PEG chain length of 550 and 875, on the structure, morphology, biocompatibility, swelling and release properties of P(HEMA/IA/550PEGDMA) and P(HEMA/IA/875PEGDMA) copolymeric hydrogels have been investigated. Preliminary biocompatibility characterization of P(HEMA/IA/PEGDMA) hydrogels, done by the cytotoxicity assays using the HeLa cell line, indicated satisfactory cytocompatibility. Swelling studies were conducted for all samples in a physiological pH and temperature range, showing a noticeable pH sensitivity and temperature dependent equilibrium swelling. The characterization by Fourier transform infrared (FTIR) spectroscopy confirmed the presence of all monomers used in the gel structure, and morphology study, performed by scanning electron microscopy (SEM), revealed no significant differences between the samples with respect to pore size. In order to elucidate the release mechanism, drug release study was carried out in vitro using two forms of vitamin B 3: nicotinamide (NAm) and nicotinic acid (NAc). The dissolution profiles were fitted to various mathematical models and the best fit was obtained for first order kinetics. The favorable swelling and drug release properties of P(HEMA/IA/PEGDMA) hydrogels make them good candidates to be used as biomaterials.

Hemocompatibility and swelling studies of poly(2-hydroxyethyl methacrylate-co-itaconic acid-co-poly(ethylene glycol) dimethacrylate) hydrogels

In this study novel series of hydrogels, based on 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA) and poly(ethylene glycol) dimethacrylates (PEGDMA) (of varying molecular weight and concentration) were prepared by free radical crosslinking copolymerization. Preliminary hemocompatibility characterization of hydrogels obtained by hemolytic activity assay indicated good compatibility with blood. Preliminary biocompatibility characterization of P(HEMA/IA/PEGDMA) hydrogels, done by the cytotoxicity assays using the HeLa cell line revails that the cell viability of all samples was the range of 97?100%, with no significant decrease in cell viability with the change of PEGDMA molecular weight and concentration. Swelling studies were conducted for all P(HEMA/IA/PEGDMA) samples in a physiological pH and temperature range and network parameters were determined. Swelling studies showed pH sensitive behaviour, typical for anionic hydrogels, and temperature dependent swelling. The effects of concentration of PEGDMA component on hydrogel swelling properties depend on the PEGDMA molecular weight. The samples with 550PEGDMA show different swelling capacities when 550PEGDMA content is changed, whereas for P(HEMA/IA/875PEGDMA) samples there was practically no difference in equilibrium degree of swelling, qe ,with varying 875PEGDMA content, which trend is the same as in the case of qe versus pH dependences. It was concluded that P(HEMA/IA/PEGDMA) hydrogels show good potential to be used as biomedical materials.

Synthesis, characterization and controlled release of cephalexin drug from smart poly(2-hydroxyethyl methacrylate/poly(alkylene glycol)(meth)acrylates hydrogels

In this work, novel hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and different poly(alkylene glycol)(meth)acrylates (BIS) were prepared by radiation-induced copolymerization. The influence of different BIS types with variation in chain length, based on ethylene glycol (EG) and/or propylene glycol (PG) pendant units, on the nature and inherent properties of P(HEMA/BIS) copolymeric hydrogels was the main idea of this paper. Swelling studies were conducted for all types of P(HEMA/BIS) copolymeric hydrogels in a wide pH and temperature range. Additional characterization of structure, morphology and thermal behaviour of the obtained hydrogels was conducted by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric (TG) analysis. The modelling of drug release and diffusion characteristics was tested using cephalexin (CEX). The results indicate that P(HEMA/BIS) hydrogels’ properties are significantly dependent on the type of BIS. The hydrogels with ethylene glycol (EG) pendant chains show a noticeable pH and/or temperature sensitivity and can be considered smart hydrogels. The introduction of propylene glycol (PG) units, pure and mixed with ethylene glycol (EG) pendant chains, can additionally tune the characteristics of such gels. Furthermore, drug release studies indicate that these types of P(HEMA/BIS) copolymeric hydrogels are suitable candidates for controlled drug release systems.

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 γ-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.

Preparation of Silver(I) Complexes with Itaconic Acid-Based Hydrogels for Biomedical Application

Silver(I) complexes based on itaconic acid hydrogel were prepared and characterized in order to examine the potential use of these materials. FTIR, AFM, in vitro fluid-uptake, metal sorption, and antibacterial activity assay measurements were used for the characterization. Silver(I) ion uptake by hydrogels based on 2-hydroxyethyl methacrylate (HEMA), ethylene glycol dimethacrylate (EGDMA), and different content of itaconic acid (2; 3.5; 5 mol%) were determined by inductively coupled plasma mass spectrometry. The coordination sites for metal ions were identified, and the stability in in-vitro condition was determined. Incorporation of silver(I) ions into hydrogels and the influence of these ions on material diffusion properties were analyzed. It was found that the itaconic acid moiety is the determining factor which influences metal ion binding and, therefore, fluid uptake inside the polymer network. Furthermore, obtained hydrogels showed a satisfactory antibacterial activity.

Macroporous hydrogels based on 2-hydroxyethyl methacrylate. Part 6: 3D hydrogels with positive and negative surface charges and polyelectrolyte complexes in spinal cord injury repair

Macroporous hydrogels are artificial biomaterials commonly used in tissue engineering, including central nervous system (CNS) repair. Their physical properties may be modified to improve their adhesion properties and promote tissue regeneration. We implanted four types of hydrogels based on 2-hydroxyethyl methacrylate (HEMA) with different surface charges inside a spinal cord hemisection cavity at the Th8 level in rats. The spinal cords were processed 1 and 6 months after implantation and histologically evaluated. Connective tissue deposition was most abundant in the hydrogels with positively-charged functional groups. Axonal regeneration was promoted in hydrogels carrying charged functional groups; hydrogels with positively charged functional groups showed increased axonal ingrowth into the central parts of the implant. Few astrocytes grew into the hydrogels. Our study shows that HEMA-based hydrogels carrying charged functional groups improve axonal ingrowth inside the implants compared to implants without any charge. Further, positively charged functional groups promote connective tissue infiltration and extended axonal regeneration inside a hydrogel bridge.

Smart hydrogels based on itaconic acid 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 properties, biocompatibility and microbe penetration capability was investigated. The mechanical properties of copolymers were investigated using the dynamic mechanical analysis (DMA), while their morphology was examined by scanning electron microscopy (SEM). The morphology and mechanical 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.

Immobilization of Urease on (HEMA/IA) Hydrogel Prepared by Gamma Radiation

In the present study, the copolymeric hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) were synthesized by gamma radiation induced radical polymerization, in order to examine the potential use of these hydrogels in immobilization of Citrullus vulgaris urease. Gelation and Swelling properties of PHEMA and copolymeric P (HEMA/IA) hydrogels with different IA contents (96.5/3.5, 94.4/5.6 and 92.5/7.5 mol) were studied in a wide pH range. Initial studies of so-prepared hydrogels show interesting pH sensitivity in swelling and immobilization. C. vulgaris urease was immobilized on HEMA/IA (92.5/7.5) at 6 kGy with 41.3% retention of activity. The properties of free and immobilized urease were compared. Immobilized urease maintained a higher relative activity than free urease at both lower and higher pH levels, indicating that the immobilized urease was less sensitive to pH changes than the free urease. The Km value of the immobilized urease was approximately 2 times higher than that of the free urease. Temperature stability was improved for immobilized enzyme. The free form exhibited a loss about 80% of activity upon incubation for 15 min at 80°C. The influence of various heavy metal ions at the concentration of l mM was improved after enzyme immobilization. The immobilization of C. vulgaris urease on HEMA/IA (92.5/7.5) at 6 kGy showed a residual activity of 47 % after 4 reuses.

Acute and delayed implantation of positively charged 2-hydroxyethyl methacrylate scaffolds in spinal cord injury in the rat

Hydrogels are nontoxic, chemically inert synthetic polymers with a high water content and large surface area that provide mechanical support for cells and axons when implanted into spinal cord tissue. Macroporous hydrogels based on 2-hydroxyethyl methacrylate (HEMA) were prepared by radical copolymerization of monomers in the presence of fractionated NaCl particles. Male Wistar rats underwent complete spinal cord transection at the T-9 level. To bridge the lesion, positively charged HEMA hydrogels were implanted either immediately or 1 week after spinal cord transection; control animals were left untreated. Histological evaluation was performed 3 months after spinal cord transection to measure the volume of the pseudocyst cavities and the ingrowth of tissue elements into the hydrogels. The hydrogel implants adhered well to the spinal cord tissue. Histological evaluation showed ingrowth of connective tissue elements, blood vessels, neurofilaments, and Schwann cells into the hydrogels. Morphometric analysis of lesions showed a statistically significant reduction in pseudocyst volume in the treated animals compared with controls and in the delayed treatment group compared with the immediate treatment group (p < 0.001 and p < 0.05, respectively). Positively charged HEMA hydrogels can bridge a posttraumatic spinal cord cavity and provide a scaffold for the ingrowth of regenerating axons. The results indicate that delayed implantation can be more effective than immediate reconstructive surgery.

Swelling and thermodynamic studies of temperature responsive 2-hydroxyethyl methacrylate/itaconic acid copolymeric hydrogels prepared via gamma radiation

The copolymeric hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) were synthesized by gamma radiation induced radical polymerization. Swelling and thermodynamic properties of PHEMA and copolymeric P(HEMA/IA) hydrogels with different IA contents (2, 3.5 and 5 mol%) were studied in a wide pH and temperature range. Initial studies of so-prepared hydrogels show interesting pH and temperature sensitivity in swelling and drug release behavior. Special attention was devoted to temperature investigations around physiological temperature (37 °C), where small changes in temperature significantly influence swelling and drug release of these hydrogels. Due to maximum swelling of hydrogels around 40 °C, the P(HEMA/IA) hydrogel containing 5 mol% of IA without and with drug-antibiotic (gentamicin) were investigated at pH 7.40 and in the temperature range 25–42 °C, in order to evaluate their potential for medical applications.

Macroporous hydrogels based on 2-hydroxyethyl methacrylate. Part 4: Growth of rat bone marrow stromal cells in three-dimensional hydrogels with positive and negative surface charges and in polyelectrolyte complexes

The growth of bone marrow stromal cells was assessed in vitro in macroporous hydrogels based on 2-hydro- xyethyl methacrylate (HEMA) copolymers with different electric charges. Copolymers of HEMA with sodium methacrylate (MA(-)) carried a negative electric charge, copolymers of HEMA with [2-(methacryloyloxy)ethyl] trimethylammonium chloride (MOETA(-)) carried a positive electric charge and terpolymers of HEMA, MA(-) and MOETA(+) carried both, positive and negative electric charges. The charges in the polyelectrolyte complexes were shielded by counter-ions. The hydrogels had similar porosities, based on a comparison of their diffusion parameters for small cations as measured by the real-time tetramethylammonium iontophoretic method of diffusion analysis. The cell growth was studied in the peripheral and central regions of the hydrogels at 2 hours and 2, 7, 14 and 28 days after cell seeding. Image analysis revealed the highest cellular density in the HEMA-MOETA(+) copolymers; most of the cells were present in the peripheral region of the hydrogels. A lower density of cells but no difference between the peripheral and central regions was observed in the HEMA-MA(-) copolymers and in polyelectrolyte complexes. This study showed that positively charged functional groups promote the adhesion of cells.

Swelling and drug release behavior of poly(2-hydroxyethyl methacrylate/itaconic acid) copolymeric hydrogels obtained by gamma irradiation

The new copolymeric hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) were prepared by gamma irradiation, in order to examine the potential use of these hydrogels in controlled drug release systems. The influence of IA content in the gel on the swelling characteristics and the releasing behavior of hydrogels, and the effect of different drugs, theophylline (TPH) and fenethylline hydrochloride (FE), on the releasing behavior of P(HEMA/IA) matrix were investigated in vitro. The diffusion exponents for swelling and drug release indicate that the mechanisms of buffer uptake and drug release are governed by Fickian diffusion. The swelling kinetics and, therefore, the release rate depends on the matrix swelling degree. The drug release was faster for copolymeric hydrogels with a higher content of itaconic acid. Furthermore, the drug release for TPH as model drug was faster due to a smaller molecular size and a weaker interaction of the TPH molecules with(in) the P(HEMA/IA) copolymeric networks.

Macroporous hydrogels based on 2-hydroxyethyl methacrylate

Crosslinked macroporous hydrogels based on 2-hydroxyethyl methacrylate (HEMA)-[2-(methacryloyloxy)ethyl]trimethylammonium chloride (MOETACl) copolymer, HEMA-MOETACl-methacrylic acid (MA) terpolymer, and on a polyelectrolyte complex of HEMA-MA copolymer with poly(MOETACl) were prepared. All the hydrogels were prepared in the presence of fractionated sodium chloride particles. The hydrogels were characterized by the number of pores and the total volume of all pores in unit volume, the average volume and the average diameter of single pore. Morphology of the hydrogels was investigated by confocal and scanning electron microscopy. The hydrogels based on polyelectrolyte complexes were also characterized by chemical composition. Homogeneous (non-porous) hydrogels with the same composition as macroporous hydrogels were prepared and characterized by their biocompatibility.