muramidase and hydroxyethyl-methacrylate

Covalent attachment of synthetic polymers to proteins, known as protein-polymer conjugation, is currently one of the main approaches for improving the physicochemical properties of these biomolecules. The most commonly employed polymer is polyethylene glycol (PEG), as evidenced by extensive research and clinical track records for its use in biopharmaceuticals. However, the occurrence of allergic reactions or hypersensitivity and the discovery of PEG antibodies, on the one hand, and the rise of controlled polymerization techniques and novel monomers, on the other hand, have been driving the search for alternative polymers for bioconjugation. The present study describes the synthesis, purification, and properties of conjugates of lysozyme with poly( N-acryloylmorpholine) (PNAM) and poly(oligoethylene glycol methyl ether methacrylate) (POEGMA). Particularly, conjugate species with distinct conjugation degrees are investigated for their residual activity, aggregation behavior, and solubility, by using a high-throughput screening approach. Our study showcases the importance of evaluating conjugates obtained by nonsite-specific modification through isolated species with discrete degrees of conjugation rather than on the batch level. Monovalent conjugates with relatively low molar mass polymers displayed equal or even higher activity than the native protein, while all conjugates showed an improved protein solubility. To achieve a comparable effect on solubility as with PEG, PNAM and POEGMA of higher molar masses were required.

Topics: Enzyme Stability; Methacrylates; Muramidase; Polyethylene Glycols; Polymers

Designing structure and morphology of macroporous hydrogels is crucial for their applications in controlled release systems of macromolecular drugs. Macroporous hydrogels, consisting of methacrylic acid (MAA) and either acryl amide (AAm) or 2-hydroxyethyl methacrylate (HEMA) (1st network), were prepared for this purpose by cryogelation (single network cryogels, SNCs). Macroporous interpenetrating polymer network (IPN) hydrogel composites were then prepared by a sequential strategy, the 2nd network consisting of chitosan (CS) cross-linked with poly(ethyleneglycol) diglycidyl ether (PEGDGE) being generated by the sorption of a CS and PEGDGE mixture in the 1st network followed by cross-linking. A strong difference in the behavior of SNCs and IPN hydrogel composites was found during the loading and release of lysozyme (LYS) used as macromolecular drug model. Thus, while the amount of LYS loaded on SNCs was higher than that loaded on the IPNs, the release of LYS from SNCs occurred at pH 2, when the ratio between MAA and AAm was 50:50, and only at pH 1 when the ratio between MAA and AAm was 70:30. The 2nd network led to the decrease of the pore size of the IPNs, mainly when the initial concentration of monomers was 10wt/v%, but the presence of CS facilitates the LYS release from IPNs, mainly at a concentration of monomer of 5wt/v%, and when HEMA was used as nonionic comonomer.

Topics: Chitosan; Cross-Linking Reagents; Delayed-Action Preparations; Drug Compounding; Drug Liberation; Hydrogels; Hydrogen-Ion Concentration; Kinetics; Methacrylates; Muramidase; Polyethylene Glycols; Porosity

A new strong cation exchanger (SCX) monolithic column was synthesized by at-line surface modification of a cryogel prepared by copolymerization of 2-hydroxyethylmethacrylate (HEMA) and glycidylmethacrylate (GMA). Sodium salt of 3-Mercaptopropane sulfonic acid (3-MPS) was used as the ligand to transform the surface of the monolith into a strong cation exchanger. The obtained material was characterized in terms of elemental analysis, infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) N2 adsorption, and used as a stationary phase for strong-cation exchange chromatography of some proteins, such as α-chymotrypsinogen, cytochrome c and lysozyme. Water permeability of the column was calculated according to Darcy's law (2.66×10(-13)m(2)). The performance of the monolithic cryogel column was evaluated on the basis of Height Equivalent to a Theoretical Plate (HETP). Retention behavior of the studied proteins was modeled on the basis of Yamamoto model to understand the role of the ion-exchange mechanism in retention behaviors. The considered proteins were successfully separated, and the obtained chromatogram was compared with that obtained with a non-functionalized cryogel column.

Topics: Adsorption; Cation Exchange Resins; Cations; Chromatography, Ion Exchange; Chymotrypsinogen; Cryogels; Cytochromes c; Methacrylates; Microscopy, Electron, Scanning; Muramidase; Proteins; Spectroscopy, Fourier Transform Infrared; Sulfonic Acids

Molecularly imprinted PHEMAH cryogels were synthesized and used for purification of carbonic anhydrase from bovine erythrocyte. Cryogels were prepared with free radical cryopolymerization of 2-hydroxyethyl methacrylate and methacryloylamido histidine and characterized by swelling degree, macroporosity, FTIR, SEM, surface area and elemental analysis. Maximum carbonic anhydrase adsorption of molecularly imprinted PHEMAH cryogel was found to be 3.16 mg/g. Selectivity of the molecularly imprinted cryogel was investigated using albumin, hemoglobin, IgG, γ-globulin, and lysozyme as competitor proteins and selectivity ratios were found to be 15.26, 60.05, 21.88, 17.61, and 17.42, respectively. Carbonic anhydrase purity was demonstrated by SDS-PAGE and zymogram results.

Topics: Adsorption; Animals; Carbonic Anhydrases; Cattle; Cryogels; Erythrocytes; Free Radicals; gamma-Globulins; Hemoglobins; Histidine; Immunoglobulin G; Methacrylates; Molecular Imprinting; Muramidase; Polymerization; Polymethacrylic Acids; Protein Binding

The immobilization of enzymes is of paramount importance to maintain their activity and stability. In this study, surface-initiated atom-transfer radical polymerization was applied to prepare poly(2-hydroxyethyl methacrylate)-block-poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) brushes on glass slides. The polymerization kinetics was followed by using a quartz crystal microbalance with dissipation monitoring and ellipsometry in terms of mass and thickness growth, respectively. The surface chemical compositions of the obtained polymer brushes were characterized by X-ray photoelectron spectroscopy. Their mass, thickness, and enzyme-immobilization ability could be easily tuned by the initiator reaction time, monomer ratio, and polymerization time. The antibacterial activity and stability of the immobilized lysozymes were studied by fluorescent staining and bacteria lysis assay, which revealed that the lysozymes on the copolymer brushes had good stability during storage at 4 °C for up to 30 days.

Topics: Bacteria; Enzymes, Immobilized; Epoxy Compounds; Methacrylates; Muramidase; Photoelectron Spectroscopy; Polymers

Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal wetting agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy-attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications.

Topics: Adsorption; Animals; Chickens; Contact Lenses; Cross-Linking Reagents; Hyaluronic Acid; Hydrogel, Polyethylene Glycol Dimethacrylate; Hydrophobic and Hydrophilic Interactions; Light; Magnetic Resonance Spectroscopy; Methacrylates; Models, Chemical; Muramidase; Photoelectron Spectroscopy; Polymerization; Silicones; Spectroscopy, Fourier Transform Infrared; Surface Properties; Water; Wetting Agents

Protein binding in hydrogels adversely affects their performance and can interfere with their usage in several biomedical applications including contact lenses. In this study we focus on understanding and modeling the mechanisms of protein transport in hydrogels, specifically focusing on the effect of protein concentration and gel crosslinking on transport. Specifically, we focus on lysozyme, the most abundant protein in tear fluid, and hydrogels of poly-hydroxyethyl methacrylate (p-HEMA), a common contact lens material. Protein uptake experiments with gels of different thicknesses showed a time scale increase as the square of the thickness suggesting diffusion controlled transport. Partition coefficient was found to be dependent on the equilibrium concentration of lysozyme, and also on the degree of crosslinking. Since transport is related to mesh size, gel modulus was obtained for various crosslinkings and utilized to estimate the mesh size. The transport data were fitted to a diffusion model and the fitted diffusivity was compared to diffusivity predicted from a model based on hydrogel mesh size. Both protein absorption and desorption data fitted the diffusion model with the same value of diffusivity, but the experimentally measured diffusivities were significantly smaller than those estimated on the basis of the gel mesh size. Models were modified to take into account protein binding to the polymer but the modified predictions were still larger than the measured values. The results of this study could assist in the development of contact lens materials that exhibit minimal protein binding, in designing cleaning regimens for protein removal from contact lenses, and in applications related to protein binding in several other biomaterials.

Topics: Contact Lenses; Hydrogels; Methacrylates; Muramidase; Protein Binding; Rheology

The crosslinked copolymeric microspheres (HEMA/NVP) of N-vinylpyrrolidone (NVP) and 2-hydroxyethyl methacrylate (HEMA) were prepared using inverse suspension polymerization method. Subsequently, the reaction of methacryloyl chloride with the hydroxyl groups on the surfaces of HEMA/NVP microspheres was performed, leading to the introduction of polymerisable double bonds onto the surfaces of microspheres HEMA/NVP. Afterward, methacrylic acid was allowed to be graft-polymerized on microspheres HEMA/NVP in the manner of "grafting from", resulting in the grafted microspheres PMAA-HEMA/NVP. The grafted microspheres PMAA-HEMA/NVP were fully characterized with several means. The graft-polymerization of MAA on microspheres HEMA/NVP was studied in detail, and the optimal reaction conditions were determined. Thereafter, the adsorption property of the grafted microspheres PMAA-HEMA/NVP for lysozyme as a basic protein model was preliminarily examined to explore the feasibility of removing deleterious basic protein such as density lipoprotein from blood. The experimental results indicate that the PMAA grafting degree on microspheres HEMA/NVP is limited because an enwinding polymer layer as a kinetic barrier on the surfaces of HEMA/NVP microspheres will be formed during the graft-polymerization, and block the graft-polymerization. In order to enhance PMAA grafting degree, reaction temperature, monomer concentration and the used amount of initiator should be effectively controlled. The experimental results also reveal that the grafted microspheres PMAA-HEMA/NVP possess very strong adsorption ability for lysozyme by right of strong electrostatic interaction.

Topics: Adsorption; Biocompatible Materials; Cross-Linking Reagents; Methacrylates; Microscopy, Electron, Scanning; Microspheres; Models, Chemical; Muramidase; Polymers; Polymethacrylic Acids; Proteins; Pyrrolidinones; Static Electricity; Temperature

The surface imprinting of basic protein lysozyme (Lys) was carried out by designing a new route. The copolymerization of N-vinylpyrrolidone (NVP) and 2-hydroxyethyl methacrylate (HEMA) was first conducted in an inverse suspension polymerization system, and the crosslinked copolymeric microspheres HEMA/NVP were prepared. Subsequently, the esterification reaction of methacryloyl (MAO) chloride with the hydroxyl groups on the surfaces of HEMA/NVP microspheres was performed, and the modified microspheres MAO-HEMA/NVP, on which a mass of polymerisable double bonds were introduced, were obtained. In the presence of lysozyme, by initiating of K(2)S(2)O(8)-NaHSO(3), the monomer methacrylic acid (MAA) in the solution was crosslink-polymerized on the surfaces of MAO-HEMA/NVP microspheres, resulting in the surface imprinting of lysozyme. After removing the template molecules, the lysozyme molecule-surface-imprinted material MIP-HEMA/NVP was obtained. Because there were strong interactions between lysozyme and monomer MAA, electrostatic interaction and hydrogen bonding, the lysozyme molecule-surface imprinting was successfully realized. The MIP-HEMA/NVP microspheres have very high binding affinity for lysozyme, and the binding capacity gets up to 216 mg/g. It is more important that MIP-HEMA/NVP microspheres have specific recognition selectivity for lysozyme, and the selectivity coefficient for lysozyme with respect to bovine hemoglobin (BHb), which was used as a contrast protein in the experiments, actually reaches 31.07. In the respect of protein imprinting, the imprinting material with such high performance is unwonted.

Topics: Adsorption; Animals; Cattle; Hemoglobins; Hydrogen-Ion Concentration; Kinetics; Methacrylates; Microspheres; Molecular Imprinting; Muramidase; Pyrrolidinones; Spectrophotometry, Infrared; Temperature

Nanoparticulate hybrid polymeric hydrogels (10-70 nm) have been obtained via the radical-induced co-polymerization of acrylic acid-functionalized chitosan with either N-isopropylacrylamide or 2-hydroxyethyl methacrylate, and the materials have been investigated for their ability to act as controlled release vehicles in ophthalmic drug delivery. Studies on the effects of network structure upon swelling properties, adhesiveness to substrates that mimic mucosal surfaces and biodegradability, coupled with in vitro drug release investigations employing ophthalmic drugs with differing aqueous solubilities, have identified nanoparticle compositions for each of the candidate drug molecules. The hybrid nanoparticles combine the temperature sensitivity of N-isopropylacrylamide or the good swelling characteristics of 2-hydroxyethyl methacrylate with the susceptibility of chitosan to lysozyme-induced biodegradation.

Topics: Acrylamides; Anti-Bacterial Agents; Chitosan; Delayed-Action Preparations; Drug Delivery Systems; Drug Stability; Eye; Humans; Hydrogels; Kinetics; Methacrylates; Models, Theoretical; Muramidase; Nanoparticles; Particle Size; Temperature

Hydrogel microparticles were produced by a radical polymerization of hydroxyethyl methacrylate-hydroxyethyl starch (HES-HEMA) in an all aqueous two-phase system (ATPS). The microspheres show a monomodal size distribution and have the ability to entrap high amounts of water. The release of proteins or other testing substances from the HES-HEMA hydrogels can be controlled by the choice of the network density of the hydrogel by varying the degree of substitution (DS), the size of the entrapped substance, and by conditions enhancing the degradation of the hydrogel network.

Topics: Chemistry, Pharmaceutical; Delayed-Action Preparations; Dextrans; Drug Carriers; Drug Delivery Systems; Fluorescein-5-isothiocyanate; Hydrogels; Hydroxyethyl Starch Derivatives; Methacrylates; Microspheres; Muramidase; Particle Size; Water

Investigations of polymer interactions in single protein solutions is a necessary step in the elucidation of in vivo early binding events during protein deposition on hydroxyethyl methacrylate-based contact lens materials. Quantity and tenacity of binding of significant tear components to groups I and IV contact lenses was assessed. Competitive binding by these components was also examined.. Adsorption on FDA groups I and IV hydrogel lenses was monitored using I-labeled protein. Lenses were incubated in increasing concentrations of radiolabeled single species proteins in solution. For competition experiments, concentration of each radiolabeled protein was held constant and the adsorption/sorption challenged with increasing concentrations of nonlabeled proteins. Lenses were soaked in phosphate-buffered saline to determine desorption.. Group IV lenses bound large amounts of lysozyme, whereas group I lenses bound highest amounts of albumin. Albumin binding to both lens types was relatively strong and could not be competed from binding by other proteins lysozyme, lactoferrin, and mucin. Mucin at high concentrations tended to positively cooperate with the binding of lactoferrin and albumin to all lenses.. Binding of proteins to hydroxyethyl methacrylate-based hydrogel lens surfaces is affected by charge and polymer components, and perhaps manufacturing processes. Albumin binds strongly to lens surfaces, and this may play an adverse role during contact lens wear.

Topics: Adsorption; Albumins; Binding, Competitive; Contact Lenses, Hydrophilic; Eye Proteins; Humans; In Vitro Techniques; Lactoferrin; Methacrylates; Mucins; Muramidase; Osmolar Concentration; Temperature; Time Factors

The wettability of poly[2-hydroxyethyl methacrylate-co-methacrylic acid] (pHEMA-MAA) soft contact lenses was investigated in the absence and presence of block copolymer surfactants and lysozyme using the sessile drop method. The advancing dynamic contact angles (Thetaw/a) values are reported for water as a function of sequential wetting and drying cycles. The Thetaw/a values for the pHEMA-MAA in the absence of surfactant and lysozyme increased from approximately 20 degrees to 100 degrees as the number of cycles increased from two to ten, and they were independent of the pHEMA-MAA bulk water content. The change from the highly hydrophilic to hydrophobic pHEMA-MAA surface could not be reversed using the sequential wetting and drying cycles even under repeated exposures to saline solution. The effect of block copolymer surfactants with different molecular weights (MW) and hydrophilic-lipophilic balance (HLB) values on the pHEMA-MAA wettability were also studied. Low Theta(w/a) values were observed for pHEMA-MAA hydrogels that were treated with T1304 (MW 10500, HLB 14) and T904 (MW 6700, HLB 15). The surface tension data indicated that these surfactants were incompletely desorbed from the pHEMA-MAA and that the rate of desorption was slow in the timescale of the cycling experiments. Comparatively, poor wettability was observed for pHEMA-MAA surfaces presoaked in T304 (MW 1650, HLB 16) and T1107 (MW 15000, HLB 24) as Thetaw/a values greater than 90 degrees were measured for these surfactants. The surface tension data indicated that the rate of desorption of T304 and T1107 from the pHEMA-MAA was rapid and that they had a low affinity to the pHEMA-MAA. High contact angles were observed for the pHEMA-MAA hydrogels treated with lysozyme and also for the T1107 presoaked pHEMA-MAA that was also treated with lysozyme. Zero wetting angles throughout the sequential cycling were observed for the T1304 pre-treated pHEMA-MAA that had been treated with lysozyme. These results suggested that the adsorbed lysozyme on the pHEMA-MAA hydrogel had no significant influence on its wetting properties when the hydrogel was pre-treated with T1304.

Topics: Contact Lenses, Hydrophilic; Hydrogel, Polyethylene Glycol Dimethacrylate; Hydrogels; Methacrylates; Muramidase; Polyhydroxyethyl Methacrylate; Polymers; Spectrophotometry; Surface Tension; Surface-Active Agents; Temperature; Time Factors; Water; Wettability

In this paper, the release of proteins from a novel self-gelling hydrogel based on biodegradable dextran microspheres is investigated. The protein-loaded macroscopic gels are obtained by hydration of mixtures of oppositely charged hydroxyethyl methacrylate-derivatized dextran microspheres with a protein solution. In media of low ionic strength (100 mM Hepes pH 7.0) it was found that the release of the entrapped model proteins (lysozyme, BSA and IgG) was slower than in saline (150 mM NaCl, 100 mM Hepes pH 7.0). The reason behind this observation is that substantial adsorption of the proteins onto the microspheres' surface and/or absorption in the microspheres takes place. Confocal images showed that independent of their crosslink density the microspheres are impermeable for BSA and IgG. BSA, bearing a negative charge at neutral pH, was adsorbed onto the surface of positively charged microspheres. Lysozyme, which is positively charged at neutral pH, was able to penetrate into the negatively charged microspheres. In saline, the gels showed continuous release of the different proteins for 25 to 60 days. Importantly, lysozyme was quantitatively and with full preservation of its enzymatic activity released in about 25 days. This emphasizes the protein friendly technology to prepare the protein-loaded gels. Mathematical modeling revealed that protein release followed Fick's second law, indicating that the systems are primarily diffusion controlled. These results show that these hydrogels are very suitable as injectable matrix for diffusion-controlled delivery of pharmaceutically active proteins.

Topics: Adsorption; Dextrans; Diffusion; Drug Carriers; Fluorescence Recovery After Photobleaching; HEPES; Hydrogels; Immunoglobulin G; Methacrylates; Microscopy, Confocal; Microspheres; Motion; Muramidase; Osmolar Concentration; Proteins; Serum Albumin, Bovine; Time Factors; Water

Many commercial soft contact lenses are based on poly-2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) hydrogels. The adsorption of proteins, albumin and lysozyme, on such contact lens surfaces may cause problems in their applications. In this work the adsorption of proteins, albumin and lysozyme, on hydrogel surfaces, AA and HEMA, was investigated as a function of concentration of protein. Also the effects of pH and ionic strength of protein solution on the adsorption of protein were examined. The obtained results indicated that the degree of adsorption of protein increased with the concentration of protein, and the adsorption of albumin on HEMA surface at the studied pHs (6.2-8.6) was higher than AA surface, whereas the adsorption of lysozyme on AA surface at the same pHs was higher than HEMA. The change in ionic strength of protein solution affected the proteins adsorption on both AA and HEMA surfaces. Also, the amount of sodium ions deposited on the AA surface was much higher than HEMA surface. This effect can be related to the negative surface charge of AA and its higher tendency for adsorption of sodium ions compared to the HEMA surface.

Topics: Acrylates; Adsorption; Albumins; Animals; Chickens; Egg Proteins; Hydrogen-Ion Concentration; Methacrylates; Muramidase; Osmolar Concentration; Sodium Chloride; Surface Properties

Modern application of soft contact lenses demands safe and comfortable wear over extended time periods up to one month. Lenses that exhibit and sustain complete water wetting allow thick tear-film deposition, minimize film rupture, and permit smooth tear recovery upon lid closure. Water contact angles determined using an air bubble captive on a lens best gauge the in-vivo wetting state. To achieve highly water wetting lenses demands that contact-angle hysteresis be eliminated and that the advancing and receding angles both approach zero. Since lens wear exposes the anterior surface to tear proteins, lens wettability should be measured in the presence of tear-film components.. A captive-bubble technique is applied to measure the advancing and receding contact angles of two commercial silicone-hydrogel lenses: PureVision (PV) and Focus Night & Day (CF) and a standard HEMA (hydroxethyl-methacrylate) hydrogel lens: Acuvue (AV). In the captive-bubble method, an air bubble immersed in aqueous solution is brought into contact with the contact lens. The contact angle through water during bubble expansion yields the receding angle. Bubble contraction gives the water advancing angle. Contact-angle hysteresis is the difference between the advancing and receding angles.. In isotonic solution, all three lenses display considerable contact-angle hysteresis with advancing angles of almost 90 degrees. When lysozyme and/or mucin were added to the aqueous solution, hysteresis was eliminated, and equivalent and high water wetting was achieved for the three lenses. Only the advancing angle in isotonic solution provided discriminating evidence for differences in surface chemistry. Covalent attachment of polyethyleneglygol (PEG) to the PV lens surface achieved complete water wetting independent of the presence of tear protein in the solution.. The captive-bubble technique provides contact angles that are relevant to on-eye lens wear. Both advancing and receding contact angles are important to lens wettability performance. When lysozyme and/or mucin are present in the solution, PV, CF, and AV lenses display low advancing and receding contact angles indicative of equivalent wettability performance. This result is due to molecular adsorption of the proteins onto the lens external surface. Covalently attached PEG on the PV lens not only provides complete water wetting but also minimizes or even eliminates protein adsorption.

Topics: Absorption; Adsorption; Contact Lenses, Hydrophilic; Methacrylates; Mucins; Muramidase; Silicone Elastomers; Surface Tension; Tears; Wettability

In this study, the release of recombinant human interleukin-2 (rhIL-2) from methacrylated dextran (dex-MA) and (lactate-)hydroxyethyl methacrylated dextran (dex-(lactate-)HEMA) hydrogels with varying crosslink density was investigated. Hydrogels derived from dex-MA are stable under physiological conditions (pH 7 and 37 degrees C), whereas dex-HEMA and dex-lactate-HEMA hydrogels degrade due to the presence of hydrolytically sensitive esters in the crosslinks of the gels. The protein release profiles both the non-degradable and degradable dextran-based hydrogels showed that with increasing crosslink density of the gel, the release of rhIL-2 decreases. From dex-MA hydrogels with an initial water content above 70%, the rhIL-2 release followed Fickian diffusion, whereas from gels with an initial water content of 70% or lower the protein was fully entrapped in the hydrogel meshes. In contrast with non-degradable dex-MA hydrogels, degradable dex-lactate-HEMA gels with comparable network characteristics (degree of methacrylate substitution and initial water content) showed an almost zero-order, degradation controlled release of rhIL-2 in a time period of 5-15 days. This paper demonstrates that the release of rhIL-2 from non-degradable dex-MA and degradable dex-lactate-HEMA gels can be modulated by the crosslink density and/or the degradation characteristics of the hydrogel. Importantly, rhIL-2 was mainly released as monomer from the hydrogels and with good retention of its biological activity.

Topics: Dextrans; Drug Stability; Hydrogels; Interleukin-2; Methacrylates; Muramidase; Recombinant Proteins

The purpose of the present study was to determine the whether contact lens wear disturbed the levels of tear proteins and to further determine whether this was a transient or continuous disruption.. Lactoferrin, lysozyme and albumin were quantitated from tears of neophyte patients and were compared with the levels of these proteins in contact lens wearers after one and six nights and 6 months of extended wear. The quantitation of these tear proteins was performed by sandwich ELISA and turbidimetric assay.. Results showed that there were no statistically significant changes in the concentration of any of the proteins investigated.. Extended wear of hydrogel lenses does not appear to alter the concentration of the major tear film proteins, indicating that the tear film is constantly replenished to maintain protein levels, which are depleted due to protein adsorption to the lens surface.

Topics: Albumins; Blotting, Western; Contact Lenses, Extended-Wear; Electrophoresis, Polyacrylamide Gel; Enzyme-Linked Immunosorbent Assay; Eye Proteins; Follow-Up Studies; Humans; Lactoferrin; Methacrylates; Muramidase; Tears

A series of hydrogels with large pores was synthesized by the precipitation polymerization of 2-hydroxyethyl methacrylate (HEMA) with crosslinking agent in aqueous solution. Such gels are potentially useful for the controlled release of large-molecular-weight species such as proteins. In this study, the release behavior of lysozyme and alpha-amylase from hydrogels formed from HEMA or HEMA with a comonomer was studied. It was found that the polymer composition affected the total amount of lysozyme released and its activity. Effects were smaller with alpha-amylase. Charged gels, containing a phosphate moiety, released larger amounts of lysozyme at a reduced rate as a result of charge-charge interactions.

Topics: alpha-Amylases; Biocompatible Materials; Delayed-Action Preparations; Drug Delivery Systems; Gels; Methacrylates; Muramidase

Hydrogels prepared by radiation-induced polymerization at a low temperature have been used as carriers for the controlled release of peptides and proteins. It was found that polymerization of 2-hydroxyethyl methacrylate in the presence of poly (ethylene glycol) methyl ether (MPEG) enabled the more porous and swellable matrics to be obtained, the higher the molecular weight of MPEG. As a consequence, protein release took place at an increasing extent and, provided that MPEG molecular weight was high enough, high molecular weight proteins could also be released. Such a state of affairs was not met in the case of hydrogels based on poly (2-hydroxyethyl acrylate). SEM analysis revealed that even high molecular weight MPEG did not give rise to any porosity, even though the degree of swelling was very high. As a result, no protein release was observed. It was therefore concluded that control of hydrogel porosity for the controlled release of large proteins is of overwhelming importance.

Topics: Alcohol Dehydrogenase; Gamma Rays; Hydrogel, Polyethylene Glycol Dimethacrylate; Methacrylates; Microscopy, Electron; Molecular Weight; Muramidase; Peptides; Polyethylene Glycols; Polymers; Proteins; Ribonucleases; Serum Albumin

A series of polymers and copolymers of 2-hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) were synthesized in order to find surfaces that would adsorb minimal amounts of protein. The adsorption of albumin, lysozyme and immunoglobulin G from a three-way mixture of these proteins in isotonic buffered saline to the polymers was measured using 125I-labeled proteins. Apparently high protein uptake on copolymers rich in HEMA was found to be due to sorption of unbound 125I by the polymers. 125I sorption by the polymers was minimized by dialysis of the protein solution to remove unbound 125I iodide and inclusion of 0.01 M sodium iodide to block uptake of residual 125I iodide. Using these improved protocols, minimal total protein uptake was observed on copolymers containing 50% or more HEMA. The majority of adsorbed protein on all p(MMA-HEMA) polymers was albumin. Total protein uptake was greatest on pMMA. Commercial contact lenses composed of copolymers of HEMA and N-vinyl pyrrolidone (NVP) or acrylamide (AAm) adsorbed small amounts of all proteins whereas copolymers of methacrylic acid (MAAc) and HEMA adsorbed much larger quantities of lysozyme. These results indicate that protein uptake by contact lens materials varies greatly with polymer composition. Artifactually high "adsorption" can occur if precautions are not taken to prevent uptake of unbound 125I.

Topics: Acrylates; Albumins; Biocompatible Materials; Contact Lenses; Eye Proteins; Immunoglobulin G; Iodine Radioisotopes; Methacrylates; Methylmethacrylates; Muramidase; Tears

The surface reactions of poly(2-hydroxyethylmethacrylate) (PHEMA) and the copolymer poly(HEMA-methacrylic acid) (PHEMA/MAA) with methyltrimethoxysilane, ethyltrimethoxysilane and phenyltrimethoxysilane have been characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. A model compound, hydroxyethyl isobutyrate was synthesized and subsequently reacted with phenyltrimethoxysilane. Its FTIR spectrum was compared with the ATR-FTIR spectra mentioned above. Protein adsorption experiments showed that silanized PHEMA/MAA soft contact lenses adsorbed less lysozyme than the untreated lenses.

Topics: Adsorption; Chemical Phenomena; Chemistry, Physical; Contact Lenses, Hydrophilic; Methacrylates; Muramidase; Polyhydroxyethyl Methacrylate; Sodium Chloride; Surface Properties