Search

This article outlines the history and development of the first hydrophilic biocompatible plastic, called PHEMA. The story traces the notable leaders in its development and provides a timeline from the initial discovery of the hydrogel material to its evolution into the modern soft contact lens. [ABSTRACT FROM AUTHOR]

More and more basic biology research focus on the single cell level. However, the way to fabricate a chemically patterned surface exist some questions such as complex fabrication process, graphic quality puzzle and so on. In this paper, we present a One-Step method based on Poly 2-hydroxyethyl methacrylate (PolyHEMA) and micromolding in capillaries (MIMIC) technology to fabricate single cell culture chip. Experimental evidence indicates that the integrity and stability of the PolyHEMA pattern can perfectly satisfy the need of long-term cell culture.

Abstract: The polluted water, mixture of chemicals and dyes, discharged by various textile and paper industries, is a serious problem for the environment, peculiarly the water. Dyes are stable to light, heat and oxidizing agents and are usually biologically non-degradable, which makes them complicated environmental pollutants. To examine the removal of dye from water, a three-dimensional poly (2-hydroxyethyl methacrylate) (PHEMA) and eosin Y were used, respectively, as a dye retention support and pollutant. The study of the interaction between dye and a hydrophilic polymer networks by the conformational modeling using computer software represents the goal of the present work. Both the swelling and ultraviolet-visible spectrophotometry studies show that the pollutant was well retained by the porous polymer network PHEMA. The conformational study of the system composed of polymer network/dye shows that the interaction of the oxygen (O) and bromine (Br) of eosin Y with the hydrogen (H) of the PHEMA depends on the polymer porosity that was varied by the cross-linking rate of the three-dimensional polymer networks. The results obtained by this work can be applied to improve the retention efficiency of such material for use in wastewater application.Graphical abstract: [ABSTRACT FROM AUTHOR]

In order to obtain target/redox shell cross-linked micelles (TCM), copolymers poly(ε-caprolactone)-poly(2-hydroxyethyl methacrylate/methacrylate-alpha lipoic acid) and poly(ε-caprolactone)-poly(2-hydroxyethyl methacrylate/methacrylate-folate, PCL-P(HEMA/HEMA-LA) and PCL-P(HEMA/HEMA-FA) were designed and synthesized. The copolymers PCL-P(HEMA/HEMA-LA) could form reduction-sensitive cross-linked micelles (CM) by using a catalytic amount of DTT. The micelles maintained high stability against dilution but were destroyed in 10 mM dithiothreitol (DTT). The drug loaded content (DLC) of CM was 8.9%, which was almost twice as much as non-cross-linked micelle (NCM). In vitro drug release at pH 7.4 showed that the cumulative release rate of CM in 36 h was less than 30%, while it was about 50% for NCM. When PCL-P(HEMA/HEMA-LA) and PCL-P(HEMA/HEMA-FA) (FA 1%, 3% and 5%) formed target/redox micelles, IC50 of TCM with FA 3% was the lowest (1.4 µg/mL) to Hela cells with excessive expression folate receptors. The cell uptake of TCM by Hela cells is higher than target non-cross-linked micelles (TNCM), while there was not much difference between both micelles uptaken by A549 cells, which are lack of folate receptors. Therefore, the drug carriers of TCM have potential to be explored as shell cross-linked target/redox drug carriers to the cancer cells on the surface with excessive folate receptors. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen peroxide is converted by catalase to molecular oxygen and water to remove oxidative stress. In this study, catalase immobilization was performed using poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) (poly(HEMA-GMA)) cryogels with different amounts of GMA. Catalase adsorption capacity of 298.7 ± 9.9 mg/g was achieved at the end of 9 h using the poly(HEMA-GMA)-250 cryogel. Kinetic parameters and the inhibitory effects of pesticides such as 4,4′-DDE and 4,4′-DDT on the activity of free and immobilized catalase enzyme were investigated. While the V max value of the immobilized enzyme was reduced 4-fold compared to the free enzyme, in the case of the comparison of the K M values, the affinity of the immobilized enzyme was increased by 1.94 times against the substrate. The inhibitory effect of 4,4′-DDT pesticide was found to be higher for the immobilized and free enzyme. NaCl (1 M, pH: 7.0) solution was used for desorption of the adsorbed catalase enzyme. A desorption ratio of 96.45% was achieved. The technique used in this study is promising regarding for the immobilization of catalase enzyme to increase the operational activity. Therefore, poly(HEMA-GMA) cryogels have the potential to be used for immobilization of catalase enzyme in the fields of biology and biochemistry. Highlights • A novel immobilization method was applied to increase the operational activity of catalase. • Immobilization process increased the storage stability of enzyme. • The solid support to onto which catalase was immobilized has good performance regarding reusability and enzyme load. [ABSTRACT FROM AUTHOR]

Abstract Poly(2-hydroxyethyl methacrylate) brushes were grown from a gold substrate by Atom Transfer Radical Polymerization (ATRP) and the material was applied as the gate dielectric layer in Organic Thin Film Transistor (OTFT) devices. The ATRP method provided 120 nm thick layers with relatively low roughness, as characterized by Atomic Force Microscopy. The layers were also investigated by Fourier Transform Infrared Spectroscopy to confirm that the polymer layer was covalently bonded to the gold surface. The synthesized polymer had very low dispersity, Ð = 1.18, indicating the well-controlled polymerization process. Dielectric Spectroscopy was used to characterize dielectric properties of the layers for potential use as the gate dielectric in OTFTs. Then, an OTFT device was subsequently constructed by deposition of a pentacene derivative as the semiconductor on the dielectric layer. The OTFT exhibits a field-effect for a relatively low operational voltage range (V DS < 30 V and V GS < 15 V). This study demonstrates that the ultrathin layers of polymer brushes grown by ATRP can be integrated into organic electronic devices such as OTFTs. Highlights • Poly(2-hydroxyethyl methacrylate) p(HEMA) grafted on gold surface. • Density of p(HEMA) brushes tailored by concentration of the initiator. • Layer of p(HEMA) brushes used as a gate insulator in organic transistors. [ABSTRACT FROM AUTHOR]

Block copolymers (BCPs) are utilized by the microelectronics industry for their ability to phase separate at very small length scales (<20 nm). By casting these BCPs as a thin film on a substrate, the BCPs can phase separate into patterns that can be used as an etching template to transfer features into the substrate. The spacing between features is determined by the natural pitch of the BCP which is dependent on both the Flory–Huggins interaction parameter, χ, and the degree of polymerization, N. The pitch is more dependent on N than χ, meaning a low N, high-χ material is required to reach small pitches. Here, the synthesis and characterization of the BCP, poly(4-tertbutylstyrene)-b-poly(hydroxyethylmethacrylate) (PtBS-b-PHEMA), is reported. Small angle x-ray scattering and atomic force microscopy showed that PtBS-b-PHEMA was able to form cylindrical and lamellar forming morphologies with a pitch of 10 nm and sub-7 nm, respectively. With these pitches, the χ of PtBS-b-PHEMA is expected to be greater than 0.4. Random copolymer underlayers were crafted for the BCP to phase separate on in an attempt to perpendicular features; however, a neutral underlayer has yet to be found. [ABSTRACT FROM AUTHOR]

Conventional technologies for ureteral stent fabrication suffer from major inconveniences such as the development of encrustations and bacteria biofilm formation. These drawbacks typically lead to the failure of the device, significant patient discomfort and an additional surgery to remove and replace the stent in the worst cases. This work focuses on the preparation of a new nanocomposite material able to show drug elution properties, biodegradation and eventually potential antibacterial activity. Poly(2-hydroxyethyl methacrylate) or the crosslinked poly(2-hydroxyethyl methacrylate)-co-poly(acrylic acid) hydrogels were prepared by the radical polymerization method and combined with a biodegradable and antibacterial filling agent, i.e., flower-like Zinc Oxide (ZnO) micropowders obtained via the hydrothermal route. The physico-chemical analyses revealed the correct incorporation of ZnO within the hydrogel matrix and its highly mesoporous structure and surface area, ideal for drug incorporation. Two different anti-inflammatory drugs (Ibuprofen and Diclofenac) were loaded within each composite and the release profile was monitored up to two weeks in artificial urine (AU) and even at different pH values in AU to simulate pathological conditions. The addition of mesoporous ZnO micropowders to the hydrogel did not negatively affect the drug loading properties of the hydrogel and it was successfully allowed to mitigate undesirable burst-release effects. Furthermore, the sustained release of the drugs over time was observed at neutral pH, with kinetic constants (k) as low as 0.05 h−1. By exploiting the pH-tunable swelling properties of the hydrogel, an even more sustained release was achieved in acidic and alkaline conditions especially at short release times, with a further reduction of burst effects (k ≈ 0.01–0.02 h−1). The nanocomposite system herein proposed represents a new material formulation for preparing innovative drug eluting stents with intrinsic antibacterial properties.

Graphical abstract Abstract In recent years, the preparation of valuable drug delivery systems (DDS) from self-assembled amphiphilic copolymers has attracted much attention since these nanomaterials provide new opportunities to solve problems such as the lack of solubility in water of lipophilic drugs, improve their bioavailability, prolong their circulation time and decrease the side effects associated with their administration. In the current study two types of biocompatible pH-responsive nanoparticles derived from poly(2-hydroxyethyl methacrylate) (pHEMA) have been used as drug nano-carriers, being one of them core cross-linked to circumvent their instability upon dilution in human fluids. The present paper deals with the optimization of the loading process of the labile, hydrophobic and highly active anticancer drug, Camptothecin (CPT) into the nanoparticles with regard to four independent variables: CPT/polymer ratio, sonication, temperature and loading time. Forty experiments were carried out and a Box–Behnken experimental design was used to evaluate the significance of the independent variables related to encapsulation efficiency and drug retention capacity. The enhanced drug loading and encapsulation efficiency values (58% and >92%, respectively) of CPT were achieved by the core cross-linked NPs in 2 h at 32 °C at CPT/polymer ratio 1.5:1 w/w and 14 min of sonication. The optimized CPT-loaded NPs were studied by dynamic light scattering and scanning electron microscopy, and an increase in size of the loaded-NP compared to the unloaded counterparts was found. Other twenty experiments were conducted to study the enability to retain CPT into the conjugates at different ionic strength values and times. The stability studies demonstrated that the core cross-linked nanocarriers displayed an excellent drug retention capacity (>90%) at 25 °C for 15 days in every ionic-strength environments whereas the non-cross-linked ones were more stable at physiological ionic strength. The optimized systems proved to be a major step forward to encapsulate and retain CPT in the NP nuclei, what makes them ideal devices to control the delivery of CPT upon the triggered acidic conditions of solid tumors. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Sulindac loaded poly(HEMA) cross-linked microparticles were synthesized via one-pot free-radical dispersion polymerisation in supercritical carbon dioxide (scCO 2 ) in presence of photocleavable diblock stabilisers based on polyethylene oxide (PEO) and poly(heptadecafluorodecyl acrylate) (PFDA) bearing a o-nitrobenzyl photosensitive junction ( hv ) (PEO- hv -PFDA), and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Poly(HEMA) cross-linked microparticles either empty or sulindac loaded were obtained with well-defined spherical morphology with the sizes between 250 and 350 nm. Additionally, upon UV-photolysis the stabiliser on the surface was cleaved which permits to microparticles to be redispersed in water leading to water swollen microgels about 2.1–3.6 µm. Moreover, the release behaviour from obtained microgels indicated the sustained release of sulindac over 10 days. Besides, the surface modification after UV-photolysis was studied and proved that the particles can be functionalised with further chemistries. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Algal growth on solid surfaces confers the advantage of combining the algal harvesting and bioprocessing steps at a single stage, in addition to the easier handling of the immobilized cells that occupy a reduced amount of space. The current work employed the application of macroporous poly(2‐hydroxyethyl methacrylate) (PHEMA) hydrogel disks as a water‐insoluble, non‐toxic and recyclable immobilization matrix for different microalgal strains (Nannochloropsis sp., Dunaliella salina, and Botryococcus braunii) that offer value‐added products for various commercial applications. RESULTS: The study demonstrated the effect of variations in the surface characteristics of the algal strains and hydrogel surfaces on the immobilization efficiencies. Gelatin was further used to modify PHEMA hydrogels to achieve higher bioaffinity and surface hydrophilicity. The results showed that highly salt‐tolerant microalgal cells (Dunaliella salina, Nannochloropsis sp.) had significantly higher tendencies to attach on the gelatin‐modified PHEMA hydrogel compared with the freshwater B. braunii colonies; embedded within an extracellular matrix mainly made of hydrophobic components, which displayed better attachment to the unmodified PHEMA hydrogels. CONCLUSION: The proposed PHEMA hydrogels are easily‐manufactured and highly durable materials with the hydrogel disks still retaining their integrity after several years when in contact with a liquid. PHEMA disks also have the benefits of having adjustable porosities by changing the composition of the polymerization mixture, and modifiable surface properties by simply binding various synthetic or natural molecules on their surfaces, which can bring several new opportunities for harvesting various microalgal cells with different surface morphologies and chemical compositions. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A molecular bottlebrush functionalized magnetic adsorbent (magGO@bottlebrush) was fabricated in this work. Poly(hydroxyethyl methacrylate) (PHEMA) was first grafted from polydopamine coated magnetic graphene oxide via surface-initiated atom transfer radical polymerization (SI-ATRP) to produce the backbone of the molecular bottlebrush. Further modification was followed by grafting poly(styrene) via a second SI-ATRP from the PHEMA chains to yield the magGO@bottlebrush. Multiple interactions including hydrophobic, π-π stacking and π-π electron-donor-acceptor interactions greatly contributed to the solute retention. The adsorbent possessed unique shape selectivity, it provided high affinity to non-planar and non-linear compounds. Profiting from densely grafted phenyl and carbonyl groups on the adsorbent, multivalent interactions were exploited to enhance the selectivity for analytes with multiple recognition motifs. Bisphenol A (BPA) was chosen as a model analyte to test real applications of the adsorbent, considering its structural features. The adsorbent owns high adsorption capacity to BPA, and can be readily used for rapid and efficient enrichment of trace BPA from water samples. [ABSTRACT FROM AUTHOR]

Expanded perlite particles were surface functionalized using poly(hydroxyethyl methacrylate) (PHEMA) thin film under radio frequency (RF) plasma conditions in a rotating-bed plasma enhanced chemical vapor deposition (PECVD) system. Using a rotating-bed system allowed effective agitation and mixing of the particles during depositions, which ensure uniform surface coating of highly porous and particulate materials. The effects of plasma power and plasma operation mode, namely pulsed and continuous modes on the deposition rates, structure, wettability and water holding capacities of expanded perlite particles were investigated. Chemical and morphological properties of uncoated and coated expanded perlites were determined by SEM, FTIR, contact angle, and BET analyses. Observed deposition rates changed between 10 and 35 nm/min., which were dependent on the deposition conditions. It was found that pulsing the discharge helped to minimize undesirable monomer fragmentation while providing better film structure. The most hydrophilic PHEMA thin films were fabricated at 50 W plasma power and under pulsed-plasma mode. When the expanded perlite was modified with PHEMA under suitable experimental conditions, the water holding capacity of untreated particles is increased by more than twenty percent. [ABSTRACT FROM AUTHOR]

Because of uncomfortable, painful and even deleterious effects of daily injection of insulin, extensive efforts are being made worldwide for developing noninvasive drug delivery systems, especially via the oral route. In this study, we synthesized hydroxyethyl methacrylate (HEMA) nanogel via emulsion polymerization method. The morphology and stability of the nanogel were characterized by scanning electronic microscope and dynamic light scattering. In vivo results showed the soft HEMA nanogel had longer half-live in the body circulation and exhibited almost negligible uptake by the macrophage cells as compared with blank cells. For the FITC-dextran tracking for intestinal penetration, the results indicated that the FITC-dextran in the soft nanogel penetrated faster from the inner side of the abdominal segment, which explained why the soft HEMA nanogel could promote intestinal absorption of encapsulated insulin. In vivo delivery of insulin encapsulated in the soft HEMA nanogel sustained blood glucose control for 12 h, and the overall bioavailability of administrated insulin was much higher than free insulin. Our results showed that the insulin-loaded HEMA nanogel was able to efficiently control blood glucose as a delivery system, suggesting the HEMA nanogel using emulsion polymerization could be an alternative carrier for oral insulin delivery. [ABSTRACT FROM AUTHOR]

Granulosa cell (GC) culture models mimicking the intrafollicular environment are limited. Such models have a great potential in reproductive toxicity studies. The buffalo, a monovulatory species like humans, could be a better model than polyovulatory rodents. Therefore, we targeted the development and characterization of three-dimensional (3D) culture systems for buffalo GCs. The GCs from small ovarian follicles (SF) maintained the CYP19 gene expression for 144 hr in a 2D culture system. Hence, GCs from SF were cultured directly in 3D using hanging drop and Poly-([2-hydroxyethyl methacrylate]) (polyHEMA) methods in the DMEM media containing 1 ng/ml FSH and 10 ng/ml IGF-1 for 144 hr. The expression profile of nine GC-specific transcripts; CYP19, TNFAIP6, AMH, PTI, NR4A1, FSHR, RUNX, LHR, and COX2/PTGS2; revealed that 3D-spheroids developed in hanging drop method maintained the GC phenotype of preovulatory follicles. Therefore, hanging drop method is a best method for culturing GCs to mimic the intrafollicular environment. [ABSTRACT FROM AUTHOR]

Polymer brushes can be useful as small-scale reactors for the controlled synthesis of nanoparticles, an approach which is gaining increasing interest. In this context, chemical crosslinking of polymer brushes could be considered as a viable approach to control the size and size distribution of the formed nanoparticles. Here we describe the application of Positron Annihilation Spectroscopy (PAS) for the characterization of crosslinked polymer brushes (brush-gels). Poly(hydroxyethyl methacrylate) (PHEMA) brushes were obtained on silicon substrates by means of a surface-initiated atom transfer radical polymerization (SI-ATRP). Crosslinking was achieved during the polymerization by adding different amounts of diethyleneglycol dimethacrylate (DEGDMA) as a difunctional monomer. The resulting brushes, both un- and crosslinked, were then post-modified with carboxylic acid groups, allowing the in situ synthesis of silver nanoparticles after ion exchange with silver nitrate and reduction with sodium borohydride. The detailed characterization of such systems is notoriously challenging and PAS proved to be an effective, non-invasive technique to acquire insight on the structure of the brushes and of their nanoparticle composites. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) and poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels are both considered as biocompatible materials with potential use in various biomedical applications including cartilage, cardiovascular stent, and soft tissue engineering. In this work, the “ever-wet” process based on in situ UV radical polymerization of HEMA monomer in BC nanofibrous structure impregnated with HEMA was used, and a series of BC-PHEMA composites was prepared. The composite structures were characterized by ATR FT-IR spectroscopy, WAXD, SEM, and TEM techniques. The strategy of using densified BC material of various cellulose fiber contents was applied to improve mechanical properties. The mechanical properties were tested under tensile, dynamic shear, and relaxation modes. The final composites contained 1 to 20 wt% of BC; the effect of the reinforcement degree on morphology, swelling capacity, and mechanical properties was investigated. The biocompatibility test of BC-PHEMA composites was performed using mouse mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

The chemical modification of bamboo culm was explored based on in situ construction of polyhydroxyethyl methylacrylate (PHEMA) and polymethyl methylacrylate (PMMA) networks into the cell walls. Scanning electron microscopy revealed that the synthesized polymers distributed in both the cell walls and the lumen with the pits blocked. The dimensional stability was tested under three water soaking-drying and moistening-drying cycles. The swelling efficiency of the treated bamboo was under 8% in three cycles of water soaking and drying cycles and was 4% in moisteningdrying cycles. The anti-swelling efficiency was 60.5%, 52.7%, and 46.3%, respectively, in the moistening-drying cycles. Laboratory tests on mold resistance showed that no mycelium formed on the treated bamboo, while the untreated control was 100% covered by mold fungi. [ABSTRACT FROM AUTHOR]

Poly(2-hydroxyethylmethacrylate-graft-ibuprofen) (IpGH) of different ibuprofen (Ibu) contents was prepared by grafting of Ibu groups on poly(2-hydroxyethyl methacrylate) (PHEMA) in an esterification reaction route. The resulted copolymers were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, thermal gravimetric analysis, X-ray diffraction, and scanning electron microscope analysis. The cytotoxicity test and the free radical scavenging ability of this material were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium (MTT) and 1,1-diphenyl-2-picryl-hydrazyl assay methods, respectively. Thein vitrorelease study of Ibu through a retro-esterification reaction of IpHG material during 3 days reveals that the release dynamic depends on the initial Ibu grafted, pH media, and the swelling degree of PHEMA. It was also revealed that the water solubility of Ibu easily reached a maximum of 0.216 mg mL−1. The diffusion of Ibu through the polymer matrix obeys the Fickian model. The estimated distribution of the cumulative drug released in different simulated digestive organs reveals that the IpHG7 containing 6.69 mol% of Ibu content showed the best performance. [ABSTRACT FROM AUTHOR]

The construction of biomaterials with which to limit the growth of cells or to limit the adsorption of proteins is essential for understanding biological phenomena. Here, we describe a novel method to simply and easily create thin layers of poly (2‐hydroxyethyl methacrylate) (p‐HEMA) for protein and cellular patterning via etching with ethanol and microfluidic devices. First, a cell culture surface or glass coverslip is coated with p‐HEMA. Next, a polydimethylsiloxane (PDMS) microfluidic is placed onto the p‐HEMA surface, and ethanol is aspirated through the device. The PDMS device is removed, and the p‐HEMA surface is ready for protein adsorption or cell plating. This method allows for the fabrication of 0.3 µm thin layers of p‐HEMA, which can be etched to 10 µm wide channels. Furthermore, it creates regions of differential protein adhesion, as shown by Coomassie staining and fluorescent labeling, and cell adhesion, as demonstrated by C2C12 myoblast growth. This method is simple, versatile, and allows biologists and bioengineers to manipulate regions for cell culture adhesion and growth. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:243–248, 2018 [ABSTRACT FROM AUTHOR]

The first objective of this work was to prepare biocompatible magnetic polymer microspheres with reactive functional groups that could withstand nonspecific protein adsorption from biological media. Carboxyl group-containing magnetic poly(2-hydroxyethyl methacrylate) (mgt.PHEMA) microspheres ∼4 μm in size were prepared by multistage swelling polymerization, precipitation of iron oxide inside their pores, and coating with an α-methoxy-ω-amino poly(ethylene glycol) (CH 3 O-PEG 750 -NH 2 or CH 3 O-PEG 5,000 -NH 2 )/α-amino-ω- t -Boc-amino poly(ethylene glycol) (H 2 N-PEG 5,000 -NH- t -Boc) mixture. The mgt.PHEMA@PEG microspheres contained ∼10 μmol COOH per g. Biocompatibility of the particles was evaluated by their treatment with human embryonic kidney cells of the HEK293 line. The microspheres did not interfere with the growth of these cells, suggesting that the particles can be considered non-toxic. A second goal of this study was to address on the interaction of the developed microspheres with macrophages that commonly eliminate foreign microbodies appearing in organisms. Murine J774.2 macrophages (J774.2) were cultured in the presence of the neat and PEGylated microspheres for 2 h. Mgt.PHEMA@PEG 5,000 microspheres significantly adhered to the surface of J774.2 macrophages but were minimally engulfed. Due to these properties, the mgt.PHEMA@PEG microspheres might be useful for application in drug delivery systems and monitoring of the efficiency of phagocytosis. [ABSTRACT FROM AUTHOR]

This paper highlights the straightforward and versatile functionalization of biporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based networks obtained from the double porogen templating approach, and their subsequent utilization as efficient catalytic supports in heterogeneous supported catalysis. Advantage of the availability of hydroxyl groups within the PHEMA-based frameworks was taken through chemical modification with carbonyl diimidazole. This key activation led to miscellaneous functionalization reactions of the materials via nucleophilic substitution or thiol-ene/thiol-yne “click” additions of functional organic molecules mainly containing amino or thiol groups. Further, in-situ generation and immobilization of gold nanoparticles (GNPs) on selected thiol- or amine-functionalized biporous frameworks allowed for the preparation of innovative GNP@PHEMA materials. The as-obtained hybrid frameworks could efficiently be used as supported catalysts in NaBH 4 -mediated reduction of 4-nitrophenol. The reusability of amine-bearing hybrid catalysts is proved over 5 successive 1 h-cycles with stable yields around 90%. [ABSTRACT FROM AUTHOR]

Cyclosporine A is prescribed for a number of ophthalmic applications such as dry eyes, uveitis in children and adolescents, vernal keratoconjunctivitis, and peripheral ulcerative keratitis. Extended release of cyclosporine from contact lenses has been explored due to the significant benefits of increased bioavailability in comparison with eye drops. Incorporation of drug loaded particles is considered to be a promising approach for increasing the drug release duration. Here we explore the feasibility of extended release of cyclosporine and possibly other hydrophobic drugs by dispersing particles that are 100% drug rather than drug loaded particles. The expected benefits are high drug loading and extended release. Specifically, we explore transport of cyclosporine in hydroxyethyl methacrylate gels for the case when the gel is loaded with high concentration of drug leading to in situ formation of particles. We explore whether we can increase the release duration from the gels by incorporation of the particles, without sacrificing light transmission which is a critical property for contact lenses. Hydrogels were prepared by free radical UV initiated polymerization with drug dissolved in the monomer solution at varying loadings. Drug release kinetics were measured from the particle loaded lenses and fitted to the Higuchi model to determine the diffusivity. The measured diffusivity is two orders of magnitude lower than estimates from Brinkman model. The differences were attributed to the high partition coefficient of about 150, which implies that a majority of the drug in the gel is bound to the polymer. The bound drug can diffuse along the surface or desorb and diffuse. The diffusivity estimates match the measured values after binding is taken into consideration. Light transmittance was measured to determine whether particle incorporation reduces the transparency. Results showed that the drug release duration could be controlled by increasing the drug loading but the transmittance was significantly reduce particularly at high drug loadings, which suggest that this approach may have limited applicability for contact lenses, but could be useful in other applications where light transmission is not critical. [ABSTRACT FROM AUTHOR]

New requirements for heat exchangers offered pool boiling heat transfer on structured and coated surfaces as one of the promising methods for effective heat removal. In this study, pool boiling experiments were conducted on polyhydroxyethylmethacrylate (pHEMA)-coated surfaces to investigate the effect of surface orientation on bubble dynamics and nucleate boiling heat transfer. pHEMA coatings with thicknesses of 50, 100, and 200 nm were deposited using the initiated chemical deposition (iCVD) method. De-ionized water was used as the working fluid. Experiments were performed on horizontal and inclined surfaces (inclination angles of 10 deg, 30 deg, 50 deg, and 70 deg) under the constant heat flux (ranging from 10 to 80 kW/m2) boundary condition. Obtained results were compared to their plain surface counterparts, and heat transfer enhancements were observed. Accordingly, it was observed that the bubble departure phenomenon was affected by heat flux and wall superheat on bare silicon surfaces, while the supply path of vapor altered the bubble departure process on pHEMA-coated surfaces. Furthermore, the surface orientation played a major role on bubble dynamics and could be considered as a mechanism for fast vapor removal from surfaces. Bubble coalescence and liquid replenishment on coated surfaces had a promising effect on heat transfer coefficient enhancement on coated surfaces. For horizontal surfaces, a maximum enhancement of 25% relative to the bare surface was achieved, while the maximum enhancement was 105% for the inclined coated surface under the optimum condition. iCVD was proven to be a practical method for coating surfaces for boiling heat transfer applications due to the obtained promising results. [ABSTRACT FROM AUTHOR]

3D gel-printing (3DGP) is a new printing method, which is based on a 2-hydroxyethyl methacrylate (HEMA) gelation system to produce complex shape parts. In this study, the 3DGP process based on a water-based gelation system was used to prepare zirconia (ZrO 2 ) ceramic parts. The water-based ZrO 2 ceramic slurry with a solid volume fraction of 50 vol% was prepared and its rheological property was characterized. The surface roughness is Ra 8.90 µm on the printed green sample, and Ra 8.25 µm on the sample after sintered at 1520 °C for 2 h. The relative density, the Vickers hardness and the transverse rupture strength of the sintered sample are 97.6%, 14.4 GPa and 450 MPa, respectively. [ABSTRACT FROM AUTHOR]

There is a need for coatings for biomedical devices and implants that can prevent the attachment of fungal pathogens while allowing human cells and tissue to appose without cytotoxicity. Here, the authors study whether a poly(2-hydroxyethylmethacrylate) (PHEMA) coating can suppress attachment and biofilm formation by Candida albicans and whether caspofungin terminally attached to surface-tethered polymeric linkers can provide additional benefits. The multistep coating scheme first involved the plasma polymerization of ethanol, followed by the attachment of α-bromoisobutyryl bromide (BiBB) onto surface hydroxyl groups of the plasma polymer layer. Polymer chains were grafted using surface initiated activators regenerated by electron transfer atom transfer radical polymerization with 2-hydroxyethylmethacrylate, yielding PHEMA layers with a dry thickness of up to 89 nm in 2 h. Hydroxyl groups of PHEMA were oxidized to aldehydes using the Albright--Goldman reaction, and caspofungin was covalently immobilized onto them using reductive amination. While the PHEMA layer by itself reduced the growth of C. albicans biofilms by log 1.4, the addition of caspofungin resulted in a marked further reduction by >4 log units to below the threshold of the test. The authors have confirmed that the predominant mechanism of action is caused by antifungal drug molecules that are covalently attached to the surface, rather than out-diffusing from the coating. The authors confirm the selectivity of surface-attached caspofungin in eliminating fungal, not mammalian cells by showing no measurable toxicity toward the myeloid leukaemia suspension cell line KG-1a. [ABSTRACT FROM AUTHOR]

Nonvolatile, ion-dense electrolytes, such as ionic liquids and deep eutectic solvents (DESs) are attractive candidates for safe, high-performance electrochemical/electrostatic energy storage devices. In this report, an inexpensive and eco-friendly DES (1 : 2 mixture of choline chloride/ethylene glycol) has been incorporated into a solid-state gel electrolyte using a chemically cross-linked polymer scaffold formed through in situ UV copolymerization of 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) diacrylate. A high room-temperature ionic conductivity of 5.7 mS cm−1 has been obtained for a DES gel containing 13.2 vol % polymer scaffold. Tunable DES gel compressive elastic modulus values, between 14 kPa and 1.0 MPa, could be obtained by varying the polymer content. Clear evidence of hydrogen-bonding interactions between the poly(HEMA) scaffold and the DES anion was revealed through species self-diffusivity measurements as well as by FTIR spectroscopy. Using a 22.9 vol % polymer-supported DES gel as electrolyte/separator in a supercapacitor prototype with activated carbon fabric electrodes, a specific capacitance of 33.3 F g−1 and an energy density of 15.8 Wh kg−1 (based on the mass of two electrodes) were obtained during discharge at a current density of 0.01 A g−1. This work supports the notion that chemically cross-linked polymer-supported DES gel electrolytes are suitable for solid-state, flexible supercapacitor applications. [ABSTRACT FROM AUTHOR]

Polymer networks interpenetrated by chitosan and 2-hydroxyethyl methacrylate (HEMA) were synthesized. The FTIR spectra confirmed crosslinking of chitosan and polymerization of HEMA. The swelling properties were studied at different pHs and depend particularly on the chitosan content of the material and the pH sensitivity of the network. DSC studies showed two vitreous transitions at approximately 98 °C and 155 °C, which correspond to the networks of p HEMA and chitosan respectively, demonstrating that the materials obtained are amorphous and interpenetrated. Creep-recovery and stress relaxation studies showed that the materials demonstrate viscoelastic behavior. Quetiapine was used as a pharmacological model for studies of controlled release, and it was found that the process is controlled by diffusion and by relaxation of the polymer network. Finally, the synthesized materials were degraded using lysozyme under simulated physiological conditions. A higher degree of degradation was observed in conjunction with an increase in the chitosan content. [ABSTRACT FROM AUTHOR]

Biomedical applications of the synthetic polymers with amino acid side moieties have been studied in light of their biocompatibility. In this work, poly(amino acid-hydroxyethyl methacrylate)s with lysine (Lys)/leucine side moieties were synthesized via reversible addition-fragmentation chain transfer polymerization, and were verified with intrinsic chirality. For biomedical uses, their antibacterial abilities as well as hemolysis and cytotoxicity were investigated. The results indicated that there were similar inhibitions for d - and l -enantiomeric polymers against Staphylococcus aureus when the polymer concentrations were lower than ~ 300 μg/mL, while the polymer containing d -Lys moiety was more effective against Escherichia coli . The d -enantiomers at concentrations < 500 μg/mL showed relatively lower hemolysis, and all the polymers showed good in vitro cell viability with concentrations lower than 200 μg/mL. It was indicated that the antibacterial amino acid-related synthetic polymers could be potentially applied for biomedical applications. [ABSTRACT FROM AUTHOR]

In this article, ion imprinted poly(hydroxyethyl methacrylate) (PHEMA) based supermacroporous cryogels were synthesized in the presence of a functional monomer, namely N-methacryloyl-histidine methyl ester (MAH), to be complexed with Ni(II) ions. Two types of cryogels (MIP1 and MIP2) were synthesized according to functional monomer/template [MAH/Ni(II)] complexing molar ratios. These cryogels were then characterized by swelling tests, FT-IR and SEM measurements and used for selective binding of Ni(II) ions from aqueous solutions and a certified material. The maximum adsorption capacities of MIP1 and MIP2 cryogels were found as 1.89 and 5.54 mg/g, respectively. Ni(II) imprinted cryogels exhibited excellent selectivity toward competitive metal ions [Fe(III), Cu(II) and Zn(II)] indicating important potential for selective removal of Ni(II) ions from aqueous solutions. In addition, Ni(II) imprinted cryogels were used repeatedly without a decrement in the binding capacity. [ABSTRACT FROM AUTHOR]

Poly(2-hydroxyethyl methacrylate) (PHEMA) films with gradient crosslinking density are the only hydrogel films capable of generating regular wrinkling patterns upon swelling, however, they were synthesized via a complicated two-stage photopolymerization. In an effort to develop a simple synthesis method, we found that one-step UV-curing of HEMA liquid always results in films with corrugated surface, which is a common issue when curing liquid prepolymers. We further found that the introduction of a physical network in the prepolymer solution could prevent the surface from corrugating during UV curing. For this purpose, linear PHEMA was added into the prepolymer solutions, and PHEMA films with a smooth surface were successfully synthesized by a simple one-step UV curing. The resulting films generate various swelling-induced wrinkling patterns, including random worms, peanuts and long-range ordered hexagons, depending on the contents of crosslinker and linear PHEMA in the prepolymer solution. Particularly, large area, highly ordered, honeycomb-like wrinkling patterns were obtained from films with proper content of crosslinker and linear PHEMA. These regular patterns are expected to find applications such as the fabrication of uniform multicellular spheroids. [ABSTRACT FROM AUTHOR]

One-pot successive three-step RAFT polymerization of 2-hydroxyethyl methacrylate (HEMA) and butyl methacrylate (BMA) in the presence of difunctional RAFT CTA is reported demonstrating successful synthesis of pentablock copolymers containing hydrophilic blocks of pHEMA and hydrophobic blocks of pBMA of low dispersity. Searching for the conditions suitable for high conversion of the monomers, polymerization was carried out in several solvents, including dioxane, butanol, dimethyl formamide, and N -methyl-2-pyrrolidone (NMP). It was shown that NMP was the best solvent enabling to achieve near full monomer conversion during building of the blocks. Effect of the solvents was substantiated by FT-IR and NMR spectroscopy of the monomer solutions. Amphiphilic pentablock copolymers were studied by DSC and contact angle measurements, and their solutions by DLS and 1 H NMR spectroscopy. These copolymers showed single glass transition and formed the layers which were more hydrophobic than the layers of pBMA and corresponding diblock copolymers. DMSO was a good solvent for both types of the blocks while chloroform promoted formation of macromolecular associates with hydrophobic corona, and water containing solutions formation of macromolecular associates and larger aggregates with hydrophilic corona. [ABSTRACT FROM AUTHOR]

This work presents an array of ion selective electrodes combined with a solid state reference electrode for analyzing of potassium and sodium ions in fluid. The sensors was fabricated using screen printing and drop casting techniques. The ion selective electrodes were made from a stack of screen printed AgCl electrode and solid state polyhydroxyethylmethacrylate hydrogel internal electrolyte layers, which were preconditioned in 0.1M KCl. The sensitivity of the sensors to potassium and sodium ions was achieved by casting a plasticized PVC based ion selective membrane, which contained an optimal ionophore to polymer ratio, directly on the hydrogel layer. The reference electrode was made on another AgCl electrode, which was covered with the same hydrogel. For both ions, sensitivities of 50mV per decade were achieved in a concentration range 10 -3 - 1M. In this concentration range, the potassium sensor had no cross sensitivity to sodium ions and vice versa . [ABSTRACT FROM AUTHOR]

In this study, poly (hydroxyethyl methacrylate) (PHEMA) nanobeads with an average size of 115 nm were prepared by emulsion polymerization. The nanobeads were characterized with infrared spectroscopy, scanning electron microscopy, and zeta size analysis. The surface area of the PHEMA nanobeads was calculated as 541.4 m2/g. Then, diethyl phthalate (DEP) removal efficiency of the PHEMA nanobeads from aqueous media was investigated. At a fixed adsorbent/solution ratio, various factors affecting the adsorption of DEP from aqueous solution such as pH, initial concentration, contact time, temperature, and adsorbent dosage were analyzed. The maximum DEP adsorption capacity of the PHEMA nanobeads was determined as 265.1 mg/g at pH 4.0, 25°C. The Sips isotherm model fits the experimental data in the wide range of DEP concentration tested (1–300 mg/L). The pseudo-first-order, pseudo-second-order, modified Ritchie’s-second-order kinetic models were used to test the adsorption kinetics. The DEP adsorption capacity of the nanobeads did not change after five batch successive usages. DEP removal efficiency of the PHEMA nanobeads from different water media such as saliva, sweat, and tap water was also evaluated. The removal efficiencies in the range from 82.4 to 100.0% demonstrate the usability of PHEMA nanobeads for DEP removal from real samples. [ABSTRACT FROM AUTHOR]

The effect of the particles size of ZnO nanoparticles, synthesized into the microstructure of honeycomb-porous block copolymer films (poly[(2-hydroxyethylmethacrylate)m- block -poly( N -phenylmaleimide)n]) with different lengths, on the thermal, morphological and optical properties of the porous-structured films were investigated. The functional nanoparticles (NPs) were synthesized by wet preparation methods involving the porous copolymer films. The presence of the copolymer allows the coordination of Zn 2 + precursor with the hydrophilic part of the self-assembled block copolymers resulting in hierarchically-ordered NP arrays. With this approach, the microphase separation inside of the polymer domains was used for the organization of pre-formed NPs in their cavities. The results indicated that the sub-domains formed by hydrophilic moiety represent an additional advantage for the diffusion and formation of ZnO nanoparticles. Absorption spectra of the ZnO NPs showed an excitation band around 300 nm, indicating a blue-shift with respect to the ZnO bulk material (at 373 nm). The size and the spherical morphology of the prepared ZnO NPs were determined by transmission electron microscopy (TEM). The overall morphology of polymer nanocomposite (ZnO embedded in the block copolymer) was determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). [ABSTRACT FROM AUTHOR]

Highly porous polymers based on 2-hydroxyethyl methacrylate (HEMA) have been successfully prepared through the high internal phase oil-in-water emulsions and further functionalized. Since functionalization of alcohol containing polymers through the direct nucleophilic substitution is rather difficult due to poor leaving ability of hydroxyl groups, the HEMA-based polymers have been modified through the halodehydroxylation and tosylation in order to obtain better leaving group residues as compared to the hydroxyl one. Conversion of hydroxyl groups into the corresponding alkyl halides and tosylates were found to be 78, 50, and 36% for the HEMA-Cl, HEMA-Br and HEMA-Ts, respectively. Further functionalization with the piperazine and tris(2-aminoethyl)amine through amine-alkylation was performed to test the leaving group ability of previously modified HEMA-Cl, HEMA-Br and HEMA-Ts polymers. Lower conversion rates for the HEMA-Cl or the HEMA-Br (between 18 and 41%) were found as compared to the HEMA-Ts (between 46 and 89%). [ABSTRACT FROM AUTHOR]

Semi-interpenetrating polymer networks (semi-IPNs) have attracted much attention in recent years as biomaterials with a high potential in tissue engineering and controlled drug release. In this article, semi-IPNs were synthetized by free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in the presence of poly( l -lactic acid) (PLLA) with contents of 5, 10 and 20 wt.% at high temperature (150 °C). The study focused on the analysis of thermal and mechanical properties, wettability, swelling kinetics in buffered solutions of different pH, and biocompatibility using fibroblasts of human embryonic skin. Segregation of the components in different microdomains was verified by morphological analysis through scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) results revealed that the poly(2-hydroxyethyl methacrylate) (PHEMA) network is amorphous and the PLLA is semi-crystalline. Mechanical analysis provided Young’s modulus values in the range 240–370 MPa in tensile tests, and storage modulus ( E ′) values at 37 °C, 1 Hz, in the range 800–1200 MPa. Equilibrium water uptake measurements displayed material dependence on composition and pH. Swelling kinetics presented good agreement with a second-order diffusion process in all media. No sample present cytotoxicity and the cell migration process occupied many semi-IPNs pores closing them and indicating good cellular recognition. In overall, these networks can be considered for their application as scaffolds for bone defects augmentation and subchondral cartilage repair. [ABSTRACT FROM AUTHOR]

This work presents an inexpensive and disposable miniaturized electrochemical sensing platform, which was fabricated on a polyethylene terephthalate substrate for continuously monitoring the ion composition of sweat. The sweat patch consisted of an area for sweat collection, integrated reference electrode and an array of screen printed AgCl electrodes for real-time monitoring chloride concentration in sweat. The printing process and thickness of the AgCl electrodes were optimized to enhance the stability of the electrode in fluid. The AgCl electrodes were stable for more than a week in fluid and had a chloride sensitivity of 58 mV per decade. The reference electrode was successfully fabricated on the same patch by adding a polyhydroxyethylmethacrylate hydrogel layer on top of one of the AgCl electrode in the array and followed by conditioning in 3 M KCl solution. The patch, which was worn on the chest of a test subject, was able to continuously monitor the chloride concentration in sweat of the test subject during an one hour treadmill exercise. Reasonable agreement was shown between the real-time measurements and control measurements of sweat samples, which were collected from the test subject and analyzed off-line. [ABSTRACT FROM AUTHOR]

Nanocomposites of poly(2-hydroxyethyl methacrylate), PHEMA, hydrogels with silver nanoparticles (Ag NPs) were produced using an in-situ bulk radical polymerization technique. The reduction of Ag + precursors to Ag NPs took place during the reaction exclusively by the hydroxyl and carbonyl groups present in HEMA monomer. The formation of silver nanoparticles was identified using XRD characteristic peaks and the surface Plasmon resonance vibration, from UV–vis spectra. FTIR data showed that the inclusion of Ag NPs in the polymer matrix affects the chemical bonds present in the polymer matrix. The thermal stability of the nanocomposites was slightly decreased compared to neat PHEMA, whereas their thermo-mechanical properties ( i.e . elastic modulus) and the glass transition temperature were increased with the amount of the Ag NPs. The polymerization activation energy of the nanocomposites, as calculated from differential isoconversional methods using non-isothermal DSC experiments, was found to vary with conversion in a different way compared to neat PHEMA. These observations were explained based on the destruction of the hydrogen bonds between the hydroxyl and either hydroxyl or carbonyl groups originally existing in neat PHEMA from the formation of the silver aggregates and their binding to the macromolecular chain. [ABSTRACT FROM AUTHOR]

The nanocomposite copolymers of poly(titanium oxide) (PTO) in an organic matrix of poly(hydroxyethyl methacrylate) (HEMA) doped by the Au nanoparticles (NPs) were synthesized in one-pot reaction. The composites were characterized as high optical transparence. It was proved by the SIMS, SAXS, and X-ray diffraction that PTO forms the 6 nm clusters uniformly distributed inside the organic polymer and chemically bonded to it. The AuNPs were formed by the UV irradiation of the copolymers containing the HAuCl embedded into the reaction mixture before the synthesis. The primary structure of the PTO clusters is close to the anatase modification of crystalline TiO. This conclusion is made on the basis of agreement between the experimental FTIR spectra of the synthesized copolymers and the calculated IR spectra of the PTO/HEMA fragments calculated by the DFT quantum chemical methods and also by XPA-analysis. The synthesized materials have high photocatalytic activity. It has been shown by methylene orange decomposition under UV irradiation. [ABSTRACT FROM AUTHOR]

Nanoparticles used in adhesive resins are prone to agglomeration, turning the material susceptible to physical failure. Quantum dots are nonagglomerated inorganic nanoparticles (1 to 10 nm) when in equilibrium. The aim of the present study was to synthesize and characterize zinc oxide quantum dots (ZnOQDs) and to develop and evaluate an adhesive resin with the addition of ZnOQDs. ZnOQDs were formulated by self-organization in chemical reaction with isopropanol and added to 2-hydroxyethyl methacrylate (HEMA). HEMA containing ZnOQDs was used for the experimental group and neat HEMA for the control group. Mean ZnOQD diameter was evaluated in isopropanol and in HEMA by ultraviolet-visible spectroscopy. The adhesives were evaluated for degree of conversion ( n = 5), softening in solvent ( n = 5), ultimate tensile strength ( n = 5), microtensile bond strength ( n = 20) at 24 h and after 6 mo, SEM-EDS (scanning electron microscopy-energy-dispersive x-ray spectroscopy; n = 3), and superresolution confocal microscopy ( n = 3). Data of microtensile bond strength after 6 mo and Knoop hardness after solvent immersion were evaluated by paired t test with a 0.05 level of significance. The other data were evaluated by independent t test with a 0.05 level of significance. Ultraviolet-visible spectroscopy indicated that the mean ZnOQD diameter remained stable in isopropanol and in HEMA (1.19 to 1.24 nm). Fourier transform infrared spectroscopy analysis showed the peak corresponding to zinc and oxygen bond (440 cm-1). The experimental group achieved a higher degree of conversion as compared with the control group and presented dentin/adhesive interface stability after 6 mo without altering other properties tested. SEM-EDS indicated 1.54 ± 0.46 wt% of zinc, and the superresolution confocal microscopy indicated nonagglomerated nanoparticles with fluorescence blinking in the polymerized adhesive. The findings of this study showed a possible and reliable method to formulate composites with nonagglomerated nanoscale fillers, shedding light on the nanoparticle agglomeration concern. [ABSTRACT FROM AUTHOR]

Microphase separation drives the structure formation in block copolymers (BCP), and it is a promising and convenient way for the preparation of well-defined hierarchically structured materials. In this work, we focus on the synthesis of amphiphilic block copolymers, i.e., polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA), via sequential anionic polymerization. Molecular weights of the prepared BCPs were in the range of 103-308 kg mol-1 with low polydispersity values (Đ = 1.03-1.25) and a PHEMA content of 17-25 vol % as proven by size exclusion chromatography (SEC) and ¹H NMR spectroscopy measurements. For the first time, the PS-b-PHEMA BCPs were subjected to the self-assembly and non-solvent-induced phase separation (SNIPS) process for the generation of integral asymmetric films on tailor-made porous paper substrates. After water immersion, the final BCP membranes reveal an isoporous open structure at the surface featuring adjustable pore diameters of 20-60 nm. It is demonstrated that a high water flux of up to 2750 L m-2 h-1 bar-1 in the fully swollen state of the membrane can be obtained. Additionally, the hydroxyl moieties of the porous BCP membranes and tailor-made paper support are further exploited for postmodification strategies by using sol-gel chemistry. For this purpose, titanium(IV) bis(ammonium lactato) dihydroxide solution (TiBALDH) is used followed by thermal treatment at 600 °C in a nitrogen atmosphere. Noteworthy, the pristine BCP porous membrane structure can be maintained having a titanium-functionalized open porous structure. [ABSTRACT FROM AUTHOR]

The aim of this study was to prepare a supermacroporous cryogel that can be used for the adsorption of cellulase. The macroporous cryogel of poly(2-hydroxyethyl methacrylate-N-methacryloyl-l-phenylalanine) [p(HEMA- MAPA)] was prepared by copolymerization of 2-hydroxyethyl methacrylate (HEMA) with a functional monomer of N-methacryloyl-l-phenylalanine (MAPA). The cryogel was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and swelling tests. The effects of several parameters such as medium pH, temperature, ionic strength, and flow rate on cellulase adsorption were also investigated. Maximum cellulase adsorption was observed at 25 °C and pH 4.0. Furthermore, adsorbed cellulase was desorbed from the cryogel by using 1.0 M NaCl. The p(HEMA-MAPA) cryogel could be used many times without the cellulase adsorption capacity decreasing significantly. [ABSTRACT FROM AUTHOR]

Structural hydrogel materials are being considered and investigated for a wide variety of biotribological applications. Unfortunately, most of the mechanical strength and rigidity of these materials comes from high polymer concentrations and correspondingly low polymer mesh size, which results in high friction coefficients in aqueous environments. Recent measurements have revealed that soft, flexible, and large mesh size hydrogels can provide ultra low friction, but this comes at the expense of mechanical strength. In this paper, we have prepared a low friction structural hydrogel sample of polyhydroxyethylmethacrylate (pHEMA) by polymerizing an entangled polymer network on the surface through a solution polymerization route. The entangled polymer network was made entirely from uncrosslinked polyacrylamide (pAAm) that was polymerized from an aqueous solution and had integral entanglement with the pHEMA surface. Measurements revealed that these entangled polymer networks could extend up to ~200 pm from the surface, and these entangled polymer networks can provide reductions in friction coefficient of almost two orders of magnitude (p>0.7 to p< 0.01). [ABSTRACT FROM AUTHOR]

Effects of the filling degree of nanodispersed silica functionalized with amino or vinylsilyl groups on polymerization of 2-hydroxyethylmethacrylate (HEMA) and on structural characteristics of the filled composites have been studied using DSC, FTIR spectroscopy and equilibrium water sorption techniques. The results obtained testify that the kinetics of surface reaction as well as the structure of the boundary layer has more significant effect on composite structure than mechanical strengthening realized by the increase in filling degree. Merging the results of thermal analysis with data on the sorption capacity suggests the formation in filled polymer of pseudo-crystalline structures in condition of cohesion energy reduced, and this process does not depend strongly on filling degree. In the case of vinyl-silica, chemical bonding of monomer HEMA to surface that isolated nanoparticles can be niggled structuring effect of filler as reinforcing material. With increasing the filling degree of polymer with silica-amino, the nature of the polymer-silica interaction changes, with highest cohesive energy for the composite with filler content around 3 mass%. It was found that samples characterized by lowest cohesive energy have lowest moisture loss during desorption. [ABSTRACT FROM AUTHOR]

The rapid and sensitive detection of aflatoxin M 1 (AFM 1 ) in milk by using surface plasmon resonance (SPR) biosensor is reported. This low molecular weight mycotoxin is analyzed using an indirect competitive immunoassay that is amplified by secondary antibodies conjugated with Au nanoparticles. In order to prevent fouling on the sensor surface by the constituents present in analyzed milk samples, an interface with poly(2-hydroxyethyl methacrylate) p(HEMA) brush was employed. The study presents a comparison of performance characteristics of p(HEMA)-based sensor with a regularly used polyethylene glycol-based architecture relying on mixed thiol self-assembled monolayer. Both sensors are characterized in terms of surface mass density of immobilized AFM 1 conjugate as well as affinity bound primary and secondary antibodies. The efficiency of the amplification strategy based on Au nanoparticle is discussed. The biosensor allowed for highly sensitive detection of AFM 1 in milk with a limit of detection (LOD) as low as 18 pg mL −1 with the analysis time of 55 min. [ABSTRACT FROM AUTHOR]

Hydrogels of poly (2-hydroxyethyl methacrylate) (pHEMA) are suitable materials for medical applications. Synthesis, structural characterization, kinetic, physical properties and cell viability of these materials are reported in this article. The system was conducted via free radical polymerization in the absence of solvents or cross-linking agents. Hydrogels were obtained with excellent dimensional stability and high thermal stability (738 K), glass transition temperature of approximately 375 K and a degree of swelling of 66 ± 4 % in ethanol. The conversion of C=C double bond of the monomer 2-hydroxyethyl methacrylate was confirmed by Fourier transform infrared spectroscopy. Results showed dense and rough morphologies in the pHEMA, presence of high molecular interactions and good resistance to various organic solvents. In vitro tests showed excellent cell viability. The materials did not display cytotoxicity, and cells proliferated and adhered at a satisfactory rate on the hydrogel. These materials have great potential for biomedical application. Graphical Abstract: pHEMA hydrogels are materials receiving great attention among researchers due to their ease of synthesis and biomedical application. This article demonstrates a new method of obtaining pHEMA hydrogels by bulk polymerization, in a single processing step and without the use of cross-linking agents. A kinetic study was evaluated, and the results of in vitro tests showed good cell proliferation.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Poly(2-hydroxyethyl methacrylate)-co-poly(4-vinyl pyridine) and poly(HEMA)-co-poly-(4-VP) copolymers were synthesized by free radical polymerization. K2S2O8 was used as an initiator. Chain lengths of the copolymer was changed by varying the monomer/initiator ratio. These polymers have molarites of 2.6 and 2.1 respectively and are called COP2 and COP4. The samples were exposed to gamma rays at room temperature. After irradiation, the EPR spectra of COP2 and COP4 were recorded between 120 K and 450 K. From the temperature dependence of the line intensity, it was concluded that unpaired spin concentration in the irradiated samples has been changing with temperature. A theoretical study, presented in this report, was aimed to test success of the machine learning methods and to select the best learning method. [ABSTRACT FROM AUTHOR]

In this paper, poly (2-hydroxyethyl methacrylate) (pHEMA) and poly (2-hydroxyethyl methacrylate)-starch (pHEMA-S) composites were prepared from 2-hydroxyethyl methacrylate and different ratio starch. The pHEMA-S showed high thermal stability and biodegradability. The biodegradability of pHEMA-S composites was in the range of 14-22 % for 4 weeks depending on the starch ratio of pHEMA-S. Then, L-ASNase was immobilized onto pHEMA-S composites. The immobilized L-ASNase was investigated with optimum temperature, pH and kinetic parameters. Immobilization improved the pH stability and thermal stability of the enzyme. The K values were 1.58 and 0.56 mM for free and immobilized enzyme, respectively. [ABSTRACT FROM AUTHOR]