Dimethacrylate Cross-linker Research Articles

A Neutron Scattering Study of the Structure of Poly(dimethylsiloxane)-Stabilized Poly(methyl methacrylate) (PDMS-PMMA) Latexes in Dodecane.

Hard-sphere particles in nonpolar solvents are an essential tool for colloid scientists. Sterically stabilized poly(methyl methacrylate) (PMMA) particles have long been used as the exemplary hard-sphere system. However, neither the particles themselves nor the poly(12-hydroxystearic acid) (PHSA) stabilizer necessary to prevent aggregation in nonpolar solvents are commercially available. To counter this, several alternatives have been proposed. In recent years, there has been an increased interest in poly(dimethylsiloxane) (PDMS) stabilizers as a commercially available alternative to PHSA, yet the structure of particles made in this way is not as well understood as those produced using PHSA. In this work, we employ small-angle neutron scattering to determine the internal structure of PDMS-stabilized PMMA particles, synthesized with and without an additional crosslinking agent. We report data consistent with a homogeneous PMMA core with a linearly decaying PDMS shell. The thickness of the shell was in excess of 50 nm, thicker than the PHSA layer typically used to stabilize PMMA but consistent with reports of the layer thickness for similar molecular weight PDMS at planar surfaces. We also show that the amount of the hydrogenous material in the particle core of the crosslinked particles notably exceeds the amount of added ethylene glycol dimethacrylate crosslinker, suggesting some entrapment of the PDMS stabilizer in the PMMA matrix.

Multichannel separation device with parallel electrochemical detection

A device with four parallel channels was designed and manufactured by 3D printing in titanium. A simple experimental setup allowed splitting of the mobile phase in four parallel streams, such that a single sample could be analysed four times simultaneously. The four capillary channels were filled with a monolithic stationary phase, prepared using a zwitterionic functional monomer in combination with various dimethacrylate cross-linkers. The resulting stationary phases were applicable in both reversed-phase and hydrophilic-interaction retention mechanisms. The mobile-phase composition was optimized by means of a window diagram so as to obtain the highest possible resolution of dopamine precursors and metabolites on all columns. Miniaturized electrochemical detectors with carbon fibres as working electrodes and silver micro-wires as reference electrodes were integrated in the device at the end of each column. Experimental separations were successfully compared with those predicted by a three-parameter retention model. Finally, dopamine was determined in human urine to further confirm applicability of the developed device.

Textural and tensile properties of thermo-responsive poly(2-(2-methoxyethoxy)ethyl methacrylate) hydrogel

ABSTRACTHydrogel dressings should be adhesive and elastic, while providing excellent functional and aesthetic features. Owing to weak intermolecular forces, various measures are undertaken to improve the hydrogel mechanical properties. Thermo-responsive poly(2-(2-methoxyethoxy)ethyl methacrylate) (poly(MEO2MA)) hydrogel fabricated with different amounts of di(ethylene glycol) dimethacrylate (DEGDMA) cross-linker was characterised using texture profile analysis. More cross-linking sites incorporated within the hydrogel limit the swelling ability where 1.0 and 10 mol-% of DEGDMA swell by 8.03 and 1.92 times, at 5°C. Hydrogel textural and tensile property correlated with the cross-linker amount. Meanwhile, network structure disentanglement within swollen hydrogel reduced the force required for deformation. Thus, the swelling behaviour, textural and tensile properties were investigated to discern the possible biomedical applications suitable for this hydrogel.

Application of Single-Ion Conducting Gel Polymer Electrolytes in Magnesium Batteries

The development of polymer electrolytes for magnesium batteries has been hindered by difficulties related to achieving sufficient magnesium ion conduction and magnesium electrodeposition. The high charge density of the magnesium cation causes it to interact with both the polar polymer matrix and any counteranions, challenging ion transport. Solvents and salts that are known to be incompatible with the magnesium electrode have widely been used in prior reports to increase ionic conductivity. Herein we report the use of a single-ion conducting magnesium gel polymer electrolyte consisting of a poly(ethylene glycol) dimethacrylate (PEGDMA) crosslinker that is copolymerized with an anionic monomer and subsequently swelled in solvents compatible with magnesium metal. Sufficient magnesium ion conductivities (>10–4 S/cm at 25 °C) were able to be achieved with specific solvents and solvent mixtures. Constant potential holds were used to interrogate magnesium electrodeposition from these electrolytes. Small amounts...

Preparation of polyurethane-acrylate and silica nanoparticle hybrid composites by a free radical network formation method

In this study, hybrid composites of polyurethane-acrylate (PUA) and silica nanoparticle were prepared by a radical method. For this aim, silica nanoparticles were chemically functionalized with 3-methacryloxypropyltrimethoxysilane. Polyurethane was synthesized and then modified with 2-hydroxyethyl methacrylate to yield PUA. Then, different amounts of modified-silica were used to prepare PUA composites by the addition of an ethylene glycol dimethacrylate crosslinker. Fourier-transform infrared spectroscopy confirmed the successful functionalization of silica nanoparticles and the preparation of PUA. Structural investigation of the functionalized-nanoparticles and also nanocomposites was carried out using X-ray diffraction and electron microscopy. According to the thermal gravimetric analysis results, char residue of \(\hbox {HSiO}_{2}\) is 86.6%, which decreases to 81.3% in the case of \(\hbox {MSiO}_{2}\) as a result of its modifier degradation content of 5.3%. PUAS5 shows main decomposition temperatures of 396.5 and \(454.9{^{\circ }}\hbox {C}\) and also char content of 5.7% at \(700{^{\circ }}\hbox {C}\). The high amount of \(\hbox {MSiO}_{2}\) can also be resulted in higher degree of crosslinking and therefore higher thermal stabilities and char residue.

Stimuli-responsive poly(hydroxyethyl methacrylate) hydrogels from carboxylic acid-functionalized crosslinkers.

Tailoring hydrogel properties by modifications of the crosslinker structure is a good method for the design of hydrogels with a wide range of properties. In this study, two novel carboxylic acid-functionalized dimethacrylate crosslinkers (1a and 2a) are synthesized by the reaction of poly(ethylene glycol) or 2-hydroxyethyl disulfide with tert-butyl α-bromomethacrylate followed by cleavage of tert-butyl groups using trifluoroacetic acid. Their copolymerization reactivity with 2-hydroxyethyl methacrylate (HEMA) investigated by photopolymerization studies performed on photo-differential scanning calorimetry shows higher reactivity of 2a compared to 1a. These crosslinkers are then used at different ratios for fabrication of pH- and redox-responsive poly(2-hydroxyethyl methacrylate)-based hydrogels. The swelling behavior of the hydrogels is found to be dependent on the structure of the crosslinker, degree of crosslinking, pH, and CaCl2 concentration. The redox-responsive behavior is demonstrated by degradation of the hydrogel upon exposure to 1,4-dithiothreitol. The dye Rhodamine 6G and the drug resorcinol are used as models to demonstrate the pH and redox dependent release of loaded compounds from the hydrogels. The electrostatic interactions between the carboxylate groups and the positively charged R6G are found to govern the release profile in DTT and counteract the diffusion of dye molecules and significant amount of release (79% in 120 hr) occurs only at highly acidic conditions. The degradation mediated release in DTT is observed better in case of resorcinol (around 88% in 5 hr). Overall, these hydrogels can be regarded as good candidates for several applications, such as matrices for controlled release, tissue repair, and regeneration.

Impacts of cross-linker chain length on the physical properties of polyampholyte hydrogels.

Polymeric tissue engineering scaffolds have shown promise to aid in regeneration and repair of damaged tissue. In particular, nonfouling polymers have been proposed for eliminating biomaterial-induced concerns such as infection, scarring, and rejection by the immune system. Polyampholyte polymers are one class of nonfouling polymers that are composed of an equimolar mixture of positively and negatively charged monomer subunits. They possess nonfouling properties, bioactive molecule conjugation capabilities, and tunable mechanical properties. In this study, the influence of the cross-linker species on the degradation behavior, mechanical strength, and nonfouling properties of polyampholytes composed of a 1:1 molar ratio of [2-(acryloyloxy)ethyl] trimethylammonium chloride (positively charged) and 2-carboxyethyl acrylate (negatively charged) monomers was investigated. Specifically, the impact of ethylene glycol repeat units on the overall material performance was evaluated by synthesizing and characterizing hydrogels containing di-, tri-, and tetra-ethylene glycol dimethacrylate cross-linker species. The degradation studies were conducted for over 100 days in Sorenson's buffer with pH values of 4.5, 7.4, and 9.0 by tracking the swelling behavior and weight change over time. The mechanical properties were assessed using compression and tensile testing to failure. The retention of the nonfouling and protein conjugation capabilities was demonstrated using fluorescently labeled bovine serum albumin. The results demonstrate the tunability of both degradation behavior and mechanical properties through the cross-linker selection, without impacting the underlying nonfouling and biomolecule delivery capabilities. Therefore, it is concluded that polyampholyte hydrogels represent a promising platform for tissue engineering.

Enhanced solid phase extraction of DNA using hydrophilic monodisperse poly(methacrylic acid-co-ethylene dimethacrylate) microparticles.

The efficiency of solid phase extraction (SPE) of DNA on polymer particles is limited by the features of the applied solid support, such as size, hydrophilicity, and functionality and their application in SPE also requires additional steps and compounds to finally obtain sufficient amount of high-quality DNA. The present study describes a preparation of sub-micrometer monodisperse poly(methacrylic acid-co-ethylene dimethacrylate) (PME) particles by precipitation polymerization. The effect of the ethylene dimethacrylate (EDMA) crosslinker concentration on morphology and particle size, which varied from 730 to 900nm, was investigated. The particles with 5 and 15wt% EDMA were selected for a study of SPE of plasmid DNA under various adsorption and elution conditions, followed by the enzymatic restriction of isolated DNA to verify a quality the nucleic acid. The particles with 15wt% EDMA were suitable for the SPE because they retained better colloidal stability during the adsorption without additional induction of DNA conformational change. The quality of isolated DNA was finally verified by enzymatic restriction by restriction endonuclease EcoRI. Moreover, the developed method using PME particles was successfully utilized for DNA isolation from Escherichia coli lysate.

Novel nanocomposite derived from ZnO/CdS QDs embedded crosslinked chitosan: An efficient photocatalyst and effective antibacterial agent.

A novel nanocomposite (cl-Ch-pMAc@ZnO/CdSQDs) has been developed under microwave irradiation via fabrication of ZnO/CdS quantum dots on anionically functionalized chitosan [i.e. poly (methacrylic acid) crosslinked chitosan (cl-Ch-pMAc) in the presence of diethylene glycol dimethacrylate (DEGDMA) crosslinker]. The structural, morphological and chemical/physical properties of crosslinked chitosan and the nanocomposites have been investigated using 13C nuclear magnetic resonance spectroscopy (13C NMR spectroscopy), high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) analyses. The nanocomposite demonstrates outstanding efficacy towards the photocatalytic degradation of cationic dyes [malachite green (MG), and safranin (SF)] and toxic organic molecule 2,4-dichloro phenol (2,4-DCP) under the exposure of sunlight. Liquid chromatography mass spectroscopy (LC-MS) studies predict that small molecules are produced by degradation. Moreover, the composite exhibits excellent antibacterial activity towards E-coli and B. subtilis. Finally, the nanocomposite can be regenerated effectively with changing the solution pH and also shows 5 times reusability without significant reduction on its efficiency.

Dimethylacrylamide gels linked by dimethacrylate cross-linkers

Poly(N,N-dimethylacrylamide) (PDMA) is a water-soluble and biocompatible polymer useful in biomedical, biotechnological and pharmaceutical application areas. In this study, dimethylacrylamide (DMA) units were connected with dimethacrylate chemical cross-linkers (DMA-xl) with various chain lengths to get homogeneous, biocompatible and mechanically strong DMA hydrogels and cryogels. In the first step, the effect of the distance between the vinyl groups of the cross-linker molecules on swelling and mechanical properties was investigated. While cross-linkers bearing longer ethylene glycol units from DMA-1 to DMA-2 bond more water molecules, DMA-9’s equilibrium swelling values are the lowest, which may be due to the better movement capability of the chains with longer cross-linker units that will increase the physical interactions between the molecules and lead to the more compact structures. In the second step, cross-linker ratio was changed with a fixed dimethacrylate group. When the mol ratio of DMA-2 is decreasing step by step from the highest to lowest concentration for the gels after synthesis, the elastic modulus decreases gradually from 30 to 6 kPa, and the gels show similar mechanical behavior in the swollen state. In the last step, the amount of cross-link units on the morphology of cryogels was investigated with DMA-2 gels. The results explicitly indicated that while the mesh size of PDMA cryogels decreased with an increase in DMA-2 concentration, the mechanical stability of the gels was increased.

Comprehensive two-dimensional monolithic liquid chromatography of polar compounds.

Two-dimensional liquid chromatography largely increases the number of separated compounds in a single run, theoretically up to the product of the peaks separated in each dimension on the columns with different selectivities. On-line coupling of a reversed-phase column with an aqueous normal-phase (hydrophilic interaction liquid chromatography) column yields orthogonal systems with high peak capacities. Fast on-line two-dimensional liquid chromatography needs a capillary or micro-bore column providing low-volume effluent fractions transferred to a short efficient second-dimension column for separation at a high mobile phase flow rate. We prepared polymethacrylate zwitterionic monolithic micro-columns in fused silica capillaries with structurally different dimethacrylate cross-linkers. The columns provide dual retention mechanism (hydrophilic interaction and reversed-phase). Setting the mobile phase composition allows adjusting the separation selectivity for various polar substance classes. Coupling on-line an organic polymer monolithic capillary column in the first dimension with a short silica-based monolithic column in the second dimension provides two-dimensional liquid chromatography systems with high peak capacities. The silica monolithic C18 columns provide higher separation efficiency than the particle-packed columns at the flow rates as high as 5mL/min used in the second dimension. Decreasing the diameter of the silica monolithic columns allows using a higher flow rate at the maximum operation pressure and lower fraction volumes transferred from the first, hydrophilic interaction dimension, into the second, reversed-phase mode, avoiding the mobile phase compatibility issues, improving the resolution, increasing the peak capacity, and the peak production rate.

Dummy molecularly imprinted solid phase extraction of climbazole from environmental water samples

Dummy molecularly imprinted polymer (DMIP) for climbazole (CBZ) was synthesized for the first time employing miconazole (MNZ) as the dummy template together with methacrylic acid (MAA) monomer, ethylene glycol dimethacrylate (EGDMA) cross-linker and acetonitrile (ACN) porogen. The selectivity and capacity of the prepared MNZ-DMIP was estimated for CBZ by high-performance liquid chromatography (HPLC) and equilibrium binding experiments. Imprinting factor (IF) with a value of 7.0 was achieved, much higher than the CBZ templated MIP (IF = 3.5). Heterogeneous binding sites were found in the MNZ-DMIP, the corresponding saturation capacity and dissociation constant for the high and low affinity binding sites were 6.761 μmol g–1 and 0.3027 mmol L–1, 43.60 μmol g–1 and 4.055 mmol L–1, respectively. High efficient method based on dummy molecularly imprinted solid phase extraction (DMISPE) coupled with HPLC was established for the selective enrichment of CBZ in river and tap water using MNZ-DMIP as sorbent. DMISPE conditions including sample loading pH/volume, selective washing and elution solvents were carefully optimized. The developed method showed good recoveries (82.3–96.2%) and repeatability (RSDs 0.6–4.9%, n = 5) for samples spiked at three different concentration levels (0.2, 1.0 and 5.0 μg L–1). The detection limit was determined as 0.012 μg L–1. The results demonstrated good potential of this method for sample pretreatment of CBZ in environmental water samples.

Impact of branching unit structure on the cloud point of highly branched polymers with lower critical solution temperature behavior

The impact of the branching unit nature on the thermal dependence of the solubility of branched poly(diethylene glycol methyl ether methacrylate) (polyDEGMEMA) is studied systematically. The polymers were prepared by radical copolymerization of DEGMEMA and dimethacrylate crosslinkers with varying hydrophilicities in the presence of an efficient chain transfer agent, CBr4. Branched polyDEGMEMA containing hydrophilic groups at the branching points derived from oligo(ethylene glycol) dimethacrylate (MW 750, 2.5 mol %, vs DEGMEMA) showed a cloud point depression of 6 °C compared to linear polyDEGMEMA, while polymers with hydrophobic groups at the branching points derived from 1,6-hexanediol dimethacrylate (HDODMA, 2.5 mol % vs DEGMEMA) showed a more significant cloud point depression of 12 °C. By increasing the amount of hydrophobic crosslinker (HDODMA) from 1.25 to 10 mol %, the cloud points of the resulting branched polymers decreased gradually from 17 °C to 1 °C, and prominent solubility thermal hysteresis was observed.

Thin Melamine Imprinted Sol Gel Coating on Silica Beads: Experimental and Statistical Physics Study

In this work, a surface molecular imprinted polymer was developed at the silica surface by the action of ethylene glycol dimethacrylate crosslinking agent with methacrylamide surface grafts. The produced adsorbents were tested for the adsorption of melamine. The adsorption mechanism of melamine was checked by means of adsorption kinetic measurements and inspection of the models governing the adsorption isotherm. The adsorption kinetics followed a pseudo-second order kinetic reaching a maximum adsorption of 2.16 mg g−1. Beside the known binding isotherm models of Langmuir and Freundlich, the adsorption isotherms were also inspected using a statistical physics model based on the energies of binding sites. It appeared that the experimental results were better described by this last approach. The variation in adsorption capacities recorded between low and high concentration ranges was related to the entropy value.

Preparation of Molecularly Imprinted Microspheres as Biomimetic Recognition Material for In Situ Adsorption and Selective Chemiluminescence Determination of Bisphenol A.

Bisphenol A (BPA) is an endocrine disrupter in environments which can induce abnormal differentiation of reproductive organs by interfering with the action of endogenous gonadal steroid hormones. In this work, the bisphenol A (BPA) molecularly-imprinted microspheres (MIMS) were prepared and used as biomimetic recognition material for in situ adsorption and selective chemiluminescence (CL) determination of BPA. Through non-covalent interaction, the BPA-MIMS was successfully prepared by Pickering emulsion polymerization using a BPA template, 4-vinylpyridine (4-VP) monomer, ethylene glycol dimethacrylate (EGDMA) cross-linker, and a SiO2 dispersion agent. The characterization of scanning electron microscopy (SEM) and energy-disperse spectroscopy (EDS) showed that the obtained MIMS possessed a regular spherical shape and narrow diameter distribution (25–30 μm). The binding experiment indicated BPA could be adsorbed in situ on the MIMS-packing cell with an apparent maximum amount Qmax of 677.3 μg g−1. Then BPA could be selectively detected by its sensitive inhibition effect on the CL reaction between luminol and periodate (KIO4), and the inhibition mechanism was discussed to reveal the CL reaction process. The CL intensity was linear to BPA concentrations in two ranges, respectively from 0.5 to 1.5 μg mL−1 with a detection limit of 8.0 ng mL−1 (3σ), and from 1.5 to 15 μg mL−1 with a limit of detection (LOD) of 80 ng mL−1 (3σ). The BPA-MIPMS showed excellent selectivity for BPA adsorption and the proposed CL method has been successfully applied to BPA determination in environmental water samples.

Biopolymeric nanogel derived from functionalized glycogen towards targeted delivery of 5-fluorouracil

We report the synthesis, characterization and application of a novel biocompatible nanogel (n-Gly/pHEMA) synthesized from glycogen and 2-hydroxyethyl methacrylate using ethylene glycol dimethacrylate crosslinker. Here mesoporous silica has been used as template. The structure of the nanogel has been investigated with the help of FTIR, 1H NMR and 13C NMR spectroscopy. The FESEM, HR-TEM and DLS analyses exhibit that the size of the nanogel is in the range of 10–50 nm. Thermal degradation kinetics suggests the higher stability of the n-Gly/pHEMA nanogel after crosslinking. The gel strength has been assessed by measurement of rheological parameters. The native nanogel shows a good compatibility with MG-63 cell lines. The n-Gly/pHEMA nanogel can effectively load 5-fluorouracil (5-FU) with encapsulation efficiency of ∼60% after 48 h. The intercellular release experiment demonstrates that 5-FU loaded nanogel can efficiently kill the MG-63 cancer cells. In vitro release profile demonstrates controlled release behaviour with higher 5-FU release rate at pH 5.5 compared to pH 7.4.

GMA‐based emulsion‐templated solid foams: Influence of co‐crosslinker on morphology and mechanical properties

ABSTRACTHighly open porous polymer foams formed from high internal phase emulsions (polyHIPEs) are attracting significant interest because of their potential applications in many areas of advanced materials science. In this work, the influence of the crosslinker or co‐crosslinkers of different molecular weights on the morphology and mechanical properties of polyHIPEs containing glycidyl methacrylate (GMA) was studied. Several poly(ethylene glycol) dimethacrylate (PEGDMA) crosslinkers were considered. The results show that introducing higher molecular weight crosslinkers into polyHIPEs produces a more open structure, with significantly increased compression strength and deformation at breakage. This eliminated the undesirable brittleness and chalkiness commonly found in polyHIPE materials. The Young's modulus of GMA‐based polyHIPEs containing 40% poly(ethylene glycol) dimethacrylate increased by 50% and the crush strength by 400% when compared with traditional GMA/ethylene glycol dimethylacrylate polyHIPEs. This improvement in mechanical properties is expected to improve the suitability of polyHIPEs for use in a wide range of applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46295.

Development and Characterisation of the Imiquimod Poly(2-(2-methoxyethoxy)ethyl Methacrylate) Hydrogel Dressing for Keloid Therapy.

The imiquimod-poly(2-(2-methoxyethoxy)ethyl methacrylate) hydrogel (poly(MEO2MA) hydrogel) dressing was developed for the keloid therapy application. Four groups of the hydrogels, including the imiquimod-poly(MEO2MA) hydrogel, crosslinked with 0.2 mol %, 0.4 mol %, 0.6 mol %, and 0.8 mol % of di(ethylene glycol) dimethacrylate cross-linker (DEGDMA), were synthesised and characterised for fabricating the imiquimod-poly(MEO2MA) hydrogel pad. The lower critical solution temperature (LCST) of the poly(MEO2MA) hydrogel was measured at approximately 28 °C and was used as a trigger to control the imiquimod loading and release. The loaded amounts of the imiquimod in the poly(MEO2MA) hydrogel, crosslinked with 0.2 mol % and 0.8 mol % of DEGDMA, were about 27.4 μg and 14.1 μg per 1 mm3 of the hydrogel, respectively. The imiquimod-release profiles of two samples were characterised in a phosphate buffered saline (PBS) solution at 37 °C and the released imiquimod amount were about 45% and 46% of the total loaded imiquimod. The Cell Counting Kit-8 (CCK-8) assay was utilised to analyse the cell viability of keloid fibroblasts cultured on the samples of imiquimod-poly(MEO2MA) hydrogel, crosslinked with 0.2 mol % and 0.8 mol % of DEGDMA. There was around a 34% decrease of the cell viabilities after 2 days, compared with the pure-poly(MEO2MA) hydrogel samples. Therefore, the developed imiquimod-poly(MEO2MA) hydrogel dressing can affect the proliferation of keloid fibroblasts. It should be possible to utilise the hydrogel dressing for the keloid therapy application.

In Situ Silver Nanowire Deposited Cross-Linked Carboxymethyl Cellulose: A Potential Transdermal Anticancer Drug Carrier.

Recently, a novel biopolymeric nanocomposite hydrogel comprised of in situ formed silver nanowires (AgNWs) deposited chemically cross-linked carboxymethyl cellulose (CMC) has been developed, which demonstrates superior efficacy as anticancer drug-curcumin carrier. The cross-linked polymer has been prepared by grafting poly [2-(methacryloyloxy) ethyl trimethylammonium chloride] on CMC using diethylene glycol dimethacrylate cross-linker. The nanocomposite hydrogel has the capability to encapsulate both hydrophobic/hydrophilic transdermal drugs. With variation in reaction conditions/parameters, several composite materials have been synthesized and depending on lower swelling/higher cross-linking and greater gel strength, an optimized grade of nanocomposite hydrogel has been selected. The developed nanocomposite hydrogel is characterized with FTIR/NMR spectra, FESEM/XRD/TGA/AFM/XPS analyses, and UV-visible spectroscopy. Rheological study has been performed to enlighten the gel strength of the composite material. The synthesized nanocomposite hydrogel is biodegradable and nontoxic to mesenchymal stem cells (hMSCs). In vitro release of curcumin suggests that in situ incorporation of AgNWs on cross-linked CMC enhanced the penetration power of nanocomposite hydrogel and released the drug in sustained way (∼62% for curcumin released in 4 days). Ex vivo rat skin permeation study confirms that the drug from both the cross-linked and nanocomposite hydrogel was permeable through the rat skin in controlled fashion. Additionally the curcumin loaded composite hydrogel can efficiently kill the MG 63 cancer cells, which has been confirmed by apoptosis study and therefore, probably be a suitable carrier for curcumin delivery toward cancer cells.

Sterilization, hydration-dehydration and tube fabrication of zwitterionic hydrogels.

Terminal sterilization of hydrogel-based biomaterials is crucial for their clinically relevant applications. The authors synthesized nonfouling zwitterionic hydrogels consisting of carboxybetaine (CB) acrylamide monomer and a carboxybetaine dimethacrylate crosslinker. The mechanical and biological stability of nonfouling hydrogels were investigated using three main terminal sterilization techniques, i.e., steam autoclave, ethylene oxide gas, and gamma irradiation. It was found that CB hydrogels are very stable at high temperature and pressure and in oxidative gas environments without changing their stress, modulus, and nonfouling properties. Gamma irradiation of CB hydrogels in dry state showed high mechanical and nonfouling stability by avoiding the adverse effect of the free radicals resulted from water inside the hydrogel network. The CB hydrogels can be dehydrated and hydrated back and forward reversibly in several cycles without any loss in mechanical properties, which is desirable for hydrogel storage, handling, and sterilization. The CB hydrogel tubes are easily prepared using a simple procedure, and they are uniformly transparent and tough after swelling. Furthermore, the good mechanical properties of the CB hydrogel tubes and their resistance to red blood cells indicate great potential of this nonfouling material for medical applications.