Pure PHEMA Research Articles

Synthesis and Evaluation of Antifungal and Antibacterial Abilities of Carbon Nanotubes Grafted to Poly(2-hydroxyethyl methacrylate) Nanocomposites.

Developing nanomaterials with the capacity to restrict the growth of bacteria and fungus is of current interest. In this study, nanocomposites of poly(2-hydroxyethyl methacrylate) (PHEMA) and carbon nanotubes (CNTs) functionalized with primary amine, hydroxyl, and carboxyl groups were prepared and characterized. An analysis by Fourier-transform infrared (FT-IR) spectroscopy showed that PHEMA chains were grafted to the functionalized CNTs. X-ray photoelectron spectroscopy suggested that the grafting reaction was viable. The morphology of the prepared nanocomposites studied by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) showed significant changes with respect to the observed for pure PHEMA. The thermal behavior of the nanocomposites studied by differential scanning calorimetry (DSC) revealed that the functionalized CNTs strongly affect the mobility of the PHEMA chains. Tests carried out by thermogravimetric analysis (TGA) were used to calculate the degree of grafting of the PHEMA chains. The ability of the prepared nanocomposites to inhibit the growth of the fungus Candida albicans and the bacteria Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was evaluated. A reduced antifungal and antibacterial capacity of the prepared nanocomposites was determined.

Study of the Thermal and Mechanical Properties of the Hydrophilic Blend Material Polyhydroxyethyl Methacrylate/Polyethylene Glycol: Hydrogen Bonding Analysis

A hydrophilic blend material is a material that can take up an important quantity of water, which makes it useful in various applications such as tissue engineering, contact lenses, and drug delivery. In this study, the polymeric blend material polyhydroxyethyl methacrylate/polyethylene glycol (pHEMA/PEG) was prepared through a UV photo-polymerization reaction; hexanediol diacrylate (HDDA) and Darocur 1,173 were used, respectively, as a cross-linking agent and a photoinitiator. The main objective of this investigation was to evaluate the impact of the PEG content on the thermal and mechanical properties of the crosslinked pHEMA/HDDA. Many analytical techniques, including Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA), were used, to analyze the bonding vibrations, the glass transition temperature (Tg), and the elastic and loss moduli, respectively. The complex viscosity was analyzed by a rheometer. The swelling and deswelling behavior of the crosslinked pHEMA/PEG in distilled water were studied over time. It was found that the PEG increased the polymerization rate of the HEMA monomer, and a significant decrease in the glass transition temperature was observed with increasing PEG quantity in the blend material, confirming its plasticizing effect. The mechanical, swelling kinetics, and rheology results showed a threshold effect at 1 wt.% for PEG. The docking analysis showed that there was more hydrogen bonding between the pure pHEMA’s chains, but the integration of PEG decreased the number of hydrogen bonds, which gave flexibility to the blend material, hence; this theoretical conclusion well agreed with the experimental results.

Mechanically robust, biocompatible, and durable PHEMA-based hydrogels enabled by the synergic effect of strong intermolecular interaction and suppressed phase separation

Poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel is highly biocompatible and stable, but its actual application in soft-tissue replacement is limited by its poor mechanical properties. This study develops a facile strategy to construct PHEMA-based hydrogels with the highest strength and toughness ever reported. The strategy relies on introducing robust coordination interactions between the carboxylate groups of copolymerized maleic acid (MA) units and Fe 3+ to suppress the phase separation of PHEMA chains from aqueous solution, thereby inducing a homogeneous network. The homogeneous network can avoid stress concentrations, and dynamic coordination crosslinking can effectively dissipate energy and simultaneously maintain network elasticity. The synergistic effects of these two factors impart exceptionally high tensile strength (3.44 MPa), elastic modulus (14.22 MPa), and toughness (4.17 MJ/m 3 ) to the hydrogels, which are 22.7, 43.1, and 24.2 times higher than those of pure PHEMA hydrogels, respectively. Such mechanical properties are comparable to human nasal and auricular cartilage. The hydrogels manifest outstanding self-recovery properties and fatigue resistance, which are essential for long-term and sustainable use. In vitro cell and in vivo animal experiments show that this strategy does not sacrifice the excellent biocompatibility and stability of the PHEMA hydrogels. These PHEMA-based hydrogels, with excellent mechanical properties, fatigue resistance, and biocompatibility, are promising candidates for replacing diseased or damaged nasal and auricular cartilage. Mechanically robust, biocompatible, and durable PHEMA-based hydrogels with cartilage mimetic properties are prepared by designing a homogeneous network with strong ionic coordination interactions. The hydrogels possess excellent mechanical properties by modulating the MA content or FeCl 3 solution concentration, which is comparable to human nasal and auricular cartilage. Good fatigue resistance properties support the hydrogels for long-term and sustainable use. Combined with long-term biocompatibility and stability in vivo , the high-performance PHEMA-based hydrogels show great application prospects as a desirable candidate material for replacing diseased or damaged nasal and auricular cartilage. • Hydrogels are designed by a homogenous network with robust coordination interactions. • The homogeneous network is induced by suppressing phase separation. • The mechanical properties of hydrogels are significantly improved by such design. • Hydrogels also manifest good biocompatibility and stability. • Hydrogels are promising candidates in nasal and auricular cartilage replacement.

Processing of pHEMA/TiO2 based nanocomposites used as an excellent dental materials

In this study, a poly(hydroxyethyl methacrylate) (pHEMA) network was prepared using hydroxyethyl methacrylate (HEMA) as a foundation material and trimethylolpropane trimethacrylate (TMPTA) and benzoyl peroxide (BPO) as cross-linking agents. The pHEMA nanocomposites were prepared by the melt processing method. In this method, a twin-screw extruder machine was used. Twin-screw extrusion is used largely for mixing, compounding, or reacting polymeric materials. The flexibility of twin- screw extrusion equipment allows this operation to be designed specifically for the formulation being processed. The nanocomposites of pHEMA/1wt%TiO2 and pHEMA/2wt%TiO2 were manufactured employing pHEMA as a matrix with the buildup of lesser quantities of titanium oxide nanoparticles TiO2 1 wt% and 2 wt% as reinforcement materials. The mechanical properties investigation of pHEMA/1wt%TiO2 and pHEMA/2wt%TiO2 nanocomposites was carried out via Multi-cyclic Indentation and Micro-scratch analysis. The microstructural analysis of the nanocomposites was studied by FESEM analysis. Important changes in microstructural behaviour with improved mechanical effects were observed in pHEMA/1wt%TiO2 and pHEMA/2wt%TiO2 nanocomposites as compared to pure pHEMA. In this work, real pHEMA and pHEMA/1wt%TiO2 and pHEMA/2wt%TiO2 nanocomposites were examined for dental applications.

Preparation and application of poly (hydroxyl ethyl methacrylate) nanocomposite hydrogels containing iron oxide nanoparticles as wound dressing

In recent years, polymeric hydrogels are widespread in the field of biological materials such as wound dressing and wound care. In this work, we report for the first time the preparation and application of pHEMA nanocomposite hydrogels containing iron oxide nanoparticles as wound dressings. For this purpose, nanocomposite hydrogels based on poly (hydroxyl ethyl methacrylate) (pHEMA) and various amounts of 5, 10, and 15 wt% iron oxide nanoparticles were successfully prepared via radical polymerization. The structure and morphology of nanocomposite hydrogels were determined by Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscope (FE-SEM), respectively. The results of gel fraction and the degree of swelling of hydrogels demonstrated that the gel percentage of pHEMA increased, and the degree of swelling decreased with increasing the percentage of nanoparticles. The WVRT and the porosity of hydrogels decreased by increasing the quantity of nanoparticles and were suitable for wound dressing applications. The effect of iron oxide nanoparticles on the mechanical properties of nanocomposite hydrogels was also studied using compression test and hardness shore A durometer. The results indicated that the compression strength, modulus, strain, and hardness are steadily increasing compared to pure hydrogel by adding nanoparticles. The maximum increase was obtained for a hydrogel sample with 15 wt% iron oxide nanoparticles. Antibacterial properties and biocompatibility were determined by the disk-diffusion and MTT assay methods, respectively. Based on the results, nanocomposite hydrogels exhibited higher percentages of cell survival and better antibacterial properties compared to pure pHEMA.

PHEMA: An Overview for Biomedical Applications.

Poly(2-hydroxyethyl methacrylate) (pHEMA) as a biomaterial with excellent biocompatibility and cytocompatibility elicits a minimal immunological response from host tissue making it desirable for different biomedical applications. This article seeks to provide an in-depth overview of the properties and biomedical applications of pHEMA for bone tissue regeneration, wound healing, cancer therapy (stimuli and non-stimuli responsive systems), and ophthalmic applications (contact lenses and ocular drug delivery). As this polymer has been widely applied in ophthalmic applications, a specific consideration has been devoted to this field. Pure pHEMA does not possess antimicrobial properties and the site where the biomedical device is employed may be susceptible to microbial infections. Therefore, antimicrobial strategies such as the use of silver nanoparticles, antibiotics, and antimicrobial agents can be utilized to protect against infections. Therefore, the antimicrobial strategies besides the drug delivery applications of pHEMA were covered. With continuous research and advancement in science and technology, the outlook of pHEMA is promising as it will most certainly be utilized in more biomedical applications in the near future. The aim of this review was to bring together state-of-the-art research on pHEMA and their applications.

Iodine-responsive poly (HEMA–PVP) hydrogel for self-regulating burst-free extended release

Swollen hydrogels with extended iodine release kinetics is highly desirable for burn and scald treatment. In this paper semi-interpenetrating poly (HEMA–PVP) hydrogels were prepared by radical polymerization followed by thermo-treatment to crosslink its PVP component. Incorporation of PVP component endows the hydrogels responsive to loaded iodine undergoing a reversible shrunken/swollen volume transition. This resulted in a self-regulating iodine release model, in which shrunken hydrogel at high iodine loading decreased drug diffusion thereby reducing burst release, and then gradually swollen hydrogel as drug release ensures rapid release of dissociated drug from strong affinity sites on hydrogel backbone, achieving a burst-free extended release. The hydrogels demonstrated 11.5-fold higher iodine loading than pure pHEMA hydrogel and showed a highest 40% volume shrink. Initial burst release of iodine was efficiently decreased from 12,894 μg/day of pure pHEMA hydrogel to 2570 μg/day of pHEMA/PVP hydrogel with 37% PVP content. Iodine-loaded hydrogels showed zero-order release at three time periods of 0–15 h, 15 h–3.5 days and 3.5–23.5 days corresponding to release rate of 2570, 776 and 493 μg/day. The work gained a new insight into swollen hydrogel drug delivery system with burst-free extended drug release kinetics.

Crosslinking Polymer Brushes with Ethylene Glycol-Containing Segments: Influence on Physicochemical and Antifouling Properties.

The introduction of different types and concentrations of crosslinks within poly(hydroxyethyl methacrylate) (PHEMA) brushes influences their interfacial, physicochemical properties, ultimately governing their adsorption of proteins. PHEMA brushes and brush-hydrogels were synthesized by surface-initiated, atom-transfer radical polymerization (SI-ATRP) from HEMA, with and without the addition of di(ethylene glycol) dimethacrylate (DEGDMA) or tetra(ethylene glycol) dimethacrylate (TEGDMA) as crosslinkers. Linear (pure PHEMA) brushes show high hydration and low modulus and additionally provide an efficient barrier against nonspecific protein adsorption. In contrast, brush-hydrogels are stiffer and less hydrated, and the presence of crosslinks affects the entropy-driven, conformational barrier that hinders the surface interaction of biomolecules with brushes. This leads to the physisorption of proteins at low concentrations of short crosslinks. At higher contents of DEGDMA or in the presence of longer TEGDMA-based crosslinks, brush-hydrogels recover their antifouling properties due to the increase in interfacial water association by the higher concentration of ethylene glycol (EG) units.

Multiwalled CNT‐pHEMA composite conduit for peripheral nerve repair

A nerve conduit is designed to improve peripheral nerve regeneration by providing guidance to the nerve cells. Conductivity of such guides is reported to enhance this process. In the current study, a nerve guide was constructed from poly(2-hydroxyethyl methacrylate) (pHEMA), which was loaded with multiwalled carbon nanotubes (mwCNT) to introduce conductivity. PHEMA hydrogels were designed to have a porous structure to facilitate the transportation of the compounds needed for cell nutrition and growth and also for waste removal. We showed that when loaded with relatively high concentrations of mwCNTs (6%, w/w in hydrogels), the pHEMA guide was more conductive and more hydrophobic than pristine pHEMA hydrogel. The mechanical properties of the composites were better when they carried mwCNT. Elastic modulus of 6% mwCNT loaded pHEMA was twofold higher (0.32 ± 0.06 MPa) and similar to that of the soft tissues. Electrical conductivity was significantly improved (11.4-fold) from 7 × 10(-3) Ω(-1).cm(-1) (pHEMA) to 8.0 × 10(-2) Ω(-1).cm(-1) (6% mwCNT loaded pHEMA). On application of electrical potential, the SHSY5Y neuroblastoma cells seeded on mwCNTs carrying pHEMA maintained their viability, whereas those on pure pHEMA could not, indicating that mwCNT helped conduct electricity and make them more suitable as nerve conduits.

Synthesis, characterization, and swelling behavior of new pH‐sensitive hydrogels derived from copolymers of 2‐hydroxyethyl methacrylate and 2‐(diisopropylamino)ethylmethacrylate

AbstractThe 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 crosslinker 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 analysis, 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. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Preparation of polymer/silica hybrid hard coatings with enhanced hydrophobicity on plastic substrates

In this study, an easy method to increase hydrophobicity of the polymer/silica hybrid coating was demonstrated. UV-curable nano-sized colloidal silica was synthesized and surface-modified both by a coupling agent, 3-(trimethoxysilyl)propyl methacrylate (MSMA), and a capping agent, trimethyethoxysiliane (TMES). The formed particles were introduced into the poly(2-hydroxyethyl methacrylate) (PHEMA) matrix to yield PHEMA/silica hybrid hard coatings on plastic substrates via a UV-curing process. Differential scanning calorimetric (DSC) analyses of the hybrids indicated increases of the glass transition temperature (Tg) with increasing silica content in the hybrids; in general, an increase of 23°C could be achieved for hybrids doped with 15wt.% silica. Thermal decomposition temperature (Td), as measured by the thermal gravimetric analyzer (TGA), was found to depend on the silica content in a trend similar to that on Tg. Specifically, a large increase of 25°C was observed when the sample contained 15wt.% silica. The pencil hardness of the PHEMA/silica hybrids coated on poly(methyl methacrylate) (PMMA) substrates can reach 5H, in comparison with 2H for pure PHEMA coating. Abrasion resistance was enhanced when silica nanoparticles were incorporated. Furthermore, due to the incorporation of TMES, hydrophobicity of the hybrid coating increased considerably as the TMES content was increased. In the extreme case, a hard surface with a water contact angle (92°) has been obtained.

Preparation and characterization of poly(hydroxyethyl methacrylate-co -poly(ethyleneglycol-methacrylate)/hydroxypropyl-chitosan) hydrogel films: Adhesion of rat mesenchymal stem cells

This study examined the effects of the surface properties of the materials, such as the hydroxyl, methyl and amino groups, on rat bone marrow derived Mesenchymal Stem Cell (MSC) seeding. A series of hydrogels were prepared in film form using 2-hydroxyethyl methacrylate (pHEMA), poly(ethyleneglycol) methacrylate (PEG-MA), and/or hydroxypropyl-chitosan (HPC). The physicochemical properties of these hydrogel films, such as water content, functional groups, contact angle, surface energy and thermal properties were affected by the composition of the materials. The ability of the MSCs to form colonies, as well as their viability on these materials were also analyzed. The water content of the hydrogel films increased with increasing PEG-MA and HPC ratio in the hydrogel. Contact angle measurements of the surface of the hydrogel films demonstrated that all the materials gave rise to a significantly hydrophilic surface compared to pure pHEMA. The blood protein interactions and platelet adhesion were reduced significantly on the surface of the materials upon the incorporation of PEG-MA compared to the control pure pHEMA and vice versa for HPC. The ability of the MSCs to adhere and form colonies on these materials was also analyzed. The results showed that these materials are suitable candidates to isolate and expand MSCs. Open image in new window

Preparation and properties of morphology controlled poly(2-hydroxyethyl methacrylate)/poly(N-vinyl pyrrolidone) double networks for biomedical use

Poly(2-hydroxyethyl methacrylate)/poly(N-vinyl pyrrolidone) (PHEMA/PVP) double networks (DN) were prepared using a sequential method by incorporating a second network of crosslinked PVP into PHEMA. We found that the distributions of the two networks can be regulated just by modulating the morphology of the first network, thus giving expected high water content of these gels. Fourier transform infrared (FTIR) spectroscopy and scanning electronic microscopy (SEM) were used to confirm the structure of the DN. The incorporation of more hydrophilic PVP enhanced swelling ability of these gels. Because of improved hydrophilicity, the PHEMA/PVP DN exhibited higher loading capability for water-soluble substance than that of pure PHEMA, while showed a slower release rate than corresponding HEMA/NVP copolymer hydrogel. It is suggested that the DN gels are potential biomaterials for wound dressing, medical implants and other drug delivery systems.

Anti-fouling poly(2-hydoxyethyl methacrylate) surface coatings with specific bacteria recognition capabilities

Poly(2-hydroxyethyl methacrylate), PHEMA, brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) on silanized glass slides bearing grafted initiators. High resolution X-ray photoelectron spectroscopy (XPS) highlighted the surface chemical changes of the glass slides upon silanization and surface-confined ATRP of HEMA. Particularly, the initiator sites from the silane were detected by their bromine Br3d core electron peak whilst the O/C atomic ratios and the high resolution C1s region of the glass–PHEMA hybrids are comparable to those of pure PHEMA, thus confirming that the PHEMA chains have indeed attached to the surface. The glass–PHEMA hybrids were found to behave as anti-fouling ultrathin coatings as they resisted non-specific Salmonella typhimurium bacterial adhesion. This behaviour is driven by the hydrophilic properties of the glass–PHEMA hybrids which were assessed by contact angle measurements. In contrast, after activation of PHEMA brushes by S. typhimurium antibodies through the trichlorotriazine coupling procedure, the bacteria specifically and strongly attached to the PHEMA-coated glass slides as judged from optical microscope observation.

Thin Hydrogel Films With Nanoconfined Surface Reactivity by Photoinitiated Chemical Vapor Deposition

Several property requirements have led to the modification of hydrogels by incorporating functional groups. The current work seeks to achieve graded functional group incorporation into hydrogel thin films using the one-step technique of photoinitiated CVD (piCVD). The functional group pentafluorophenylmethacrylate (PFM) is copolymerized with hydroxyethyl methacrylate (HEMA). Because PFM reacts easily with amine groups, the incorporation of PFM results in a platform for subsequent functionalization. The graded copolymer confines the PFM to the near surface region (∼20 nm) allowing the control of the hydrogel film properties independently of the surface reactivity. Although homogeneous incorporation of PFM in the hydrogel matrix inhibits swelling, the swollen water content of pure pHEMA is nearly preserved in the graded copolymer. FTIR spectroscopy shows that the absorption peaks corresponding to the fluorinated phenyl ring in the graded copolymer disappear after functionalization with O,O-bis (2-aminoethyl) polyethylene (PEG-diamine), suggesting a nearly complete conversion of the PFM bonds.

Heparin‐coated poly(hydroxyethyl methacrylate/albumin) hydrogel networks:In vitrohemocompatibility evaluation for vascular biomaterials

AbstractHuman serum albumin (AL) containing poly(hydroxyethyl methacrylate) (pHEMA; in tube form with an inner diameter of 6 mm) was synthesized for blood‐contacting hydrogel networks via UV‐initiated photopolymerization at 25°C. Tensile and breaking tests of pHEMA and pHEMA–AL‐1–4 hydrogel networks were studied at their equilibrium water content. The mechanical strength of the hydrogel networks was found to be lowered by an increase in the ratio of AL in the polymer networks. To increase the blood compatibility and prevent thrombus formation, the surface of the pHEMA and pHEMA–AL‐3 hydrogel compositions were coated with heparin (HEP). Contact‐angle studies showed that the polarities (%) of the pHEMA–AL‐3 and pHEMA–AL‐3–HEP hydrogel networks were significantly increased in comparison with that of pure pHEMA. The fibrinogen adsorption and platelet adhesion were also reduced after the incorporation of AL and HEP into/onto hydrogel networks in comparison with the pure pHEMA control. Blood compatibility tests of the prepared hydrogel networks, which were intended to be used as blood‐contacting materials, were examined with various parameters, such as the hemolytic activity, prothrombin time, activated thromboplastin time, and loss of blood cells in blood. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Preparation and properties of modified PHEMA hydrogel with sulfonated PEG graft

AbstractA novel poly(ethylene glycol) (PEG) macromer with a methacryloyl and sulfonic acid group at each end of the chain was prepared. Modified hydroxyethyl methacrylate (HEMA) based hydrogels were synthesized by crosslinking polymerization of HEMA in the presence of the above‐mentioned PEG macromer. The effect of the sulfonated PEG graft was examined by comparing the swelling properties with those of a pure poly(hydroxyethyl methacrylate) (PHEMA) hydrogel. The modified PHEMA hydrogel exhibited increasing water absorbency with increasing sulfonated PEG content up to 15 wt %. These hydrogels with the sulfonated PEG graft exhibited a more hydrophilic character than the pure PHEMA gel. Also the swelling degree varied slightly with pH, showing increased swelling at higher pH probably due to the presence of the anionic sulfonate group on the PEG end chain. In addition, the protein adsorption test showed a lower level of fibrinogen adsorption from the sulfonated poly(ethylene glycol) (SPEG) modified gel than on the homo PHEMA hydrogel. Interestingly, scanning electron microscopy showed that the porous and rather uniform morphology of the gels changed with increasing sulfonated PEG content in PHEMA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2484–2489, 2007

Probing the microenvironment of an oligo-(p-phenylene vinylene) derivative encapsulated in polymer-impregnated sol-gel silica matrix

Polymer-impregnated silica sol-gel composite materials are hosts for organics in advanced optics application. An oligo-phenylene vinylene derivative 4,4′-(1,4-phenylene dithenylene)-bis-(N-methyl pyridinium iodide) (OPVD) was introduced to poly(hydroxyethyl methacrylate) (PHEMA)-impregnated silica composite film by the sol-gel process. By comparing the X-ray diffraction, UV-visible spectra, steady-state and time-resolved fluorescence spectra of OPVD in three solid matrices (PHEMA/silica composite film, pure PHEMA film, and pure silica film), the similar results of PHEMA/silica composite film and pure PHEMA film demonstrate that the OPVD is primarily surrounded by a PHEMA-like environment in the composite matrix. The model of such structure is presented, which is useful for further understanding and optimizing of properties of doped sol-gel materials.

Vascularization of PEG-grafted macroporous hydrogel sponges: a three-dimensional in vitro angiogenesis model using human microvascular endothelial cells.

Vascular tissue can penetrate implants that have an interconnected porous structure. The extent of vascularization is heavily dependent on a number of factors, including the nature of the material as well as the size and porosity of the implant's pore morphology. Currently, it is still not clear what mechanisms are controlling this response. In this work, in vitro human microvascular endothelial cell (HMVEC) experiments employed in angiogenesis research have been adapted as a screening technique for biomaterial vascularization. Hydrogels composed of poly(2-hydroxy ethyl methacrylate) (PHEMA) containing poly(ethylene glycol) (PEG) grafts were capable of supporting in vitro tubule formation. The sizes and lengths of tubules were dependent upon the porosity of the polymer network and pore sizes. When compared to the pure PHEMA sponges, PEG-grafted networks possessed a more lattice-type structure, with greater pore interconnection. As a result, these polymers were better suited to supporting tubule formation.

Development of hybrid materials based on hydroxyethylmethacrylate as supports for improving cell adhesion and proliferation

A novel hydrogel based on 2-hydroxyethylmethacrylate and fumed silica nanoparticles is presented. The filler was mixed at increasing amount (3–40% w/w) to the organic monomer, before accomplish thermal polymerization. The hybrid composite materials obtained were characterized as far as concern the physical–chemical stability and sorption behaviour in water and water solutions. The novel hybrid hydrogels were compared to poly(hydroxyethylmethacrylate) (pHEMA) on cytocompatibility and ability to elicit cell adhesion and proliferation. These in vitro assays showed that the first ones were supporting cell growth better then pHEMA, moreover experiments on murine fibroblasts showed improved adhesion and proliferation with the increase of the nanomeric filler content. For a more physiological response, the in vitro tests should match biomaterials with cell populations typical of the implant site. Therefore, in view of future applications of these composites as scaffolds for bone engineering, in a successive step of our research we selected primary cultures of human osteoblasts (OB) as the most appropriate models to study the in vitro performance of these materials. The preliminary results obtained confirmed the remarkable improvement of OB adhesion properties of the new hybrids with respect to pure pHEMA.