Mechanism-Guided Discovery of Cleavable Comonomers for Backbone Deconstructable Poly(methyl methacrylate)

The development of cleavable comonomers (CCs) with suitable copolymerization reactivity paves the way for the introduction of backbone deconstructability into polymers. Recent advancements in thionolactone-based CCs, exemplified by dibenzo[c,e]-oxepine-5(7H)-thione (DOT), have opened promising avenues for the selective deconstruction of multiple classes of vinyl polymers, including polyacrylates, polyacrylamides, and polystyrenics. To date, however, no thionolactone CC has been shown to copolymerize with methacrylates to an appreciable extent to enable polymer deconstruction. Here, we overcome this challenge through the design of a new class of benzyl-functionalized thionolactones (bDOTs). Guided by detailed mechanistic analyses, we find that the introduction of radical-stabilizing substituents to bDOTs enables markedly increased and tunable copolymerization reactivity with methyl methacrylate (MMA). Through iterative optimizations of the molecular structure, a specific bDOT, F-p-CF3PhDOT, is discovered to copolymerize efficiently with MMA. High molar mass deconstructable PMMA-based copolymers (dPMMA, Mn > 120 kDa) with low percentages of F-p-CF3PhDOT (1.8 and 3.8 mol%) are prepared using industrially relevant bulk free radical copolymerization conditions. The thermomechanical properties of dPMMA are similar to PMMA; however, the former is shown to degrade into low molar mass fragments (<6.5 kDa) under mild aminolysis conditions. This work presents the first example of a radical ring-opening CC capable of nearly random copolymerization with MMA without the possibility of cross-linking and provides a workflow for the mechanism-guided design of deconstructable copolymers in the future.

Dual stimuli-responsive delivery system for self-regulated colon-targeted delivery of poorly water-soluble drugs

Inflammatory bowel disease (IBD) are chronic inflammatory conditions which cause significant patient morbidity. Local drug delivery to the colon can improve treatment efficacy and reduce side effects associated with IBD treatment. Smart drug delivery systems are designed to regulate the release of therapeutic agents at the desired site of action. pH-responsive drug carriers have been previously utilised for improved oral drug delivery beyond stomach harsh conditions. Additionally, the colon possesses a diverse microbiome secreting bioactive molecules e.g., enzymes, that can be exploited for targeted drug delivery. We herein synthesised and characterised a 2-hydroxyethyl methacrylate and methacrylic acid copolymer, crosslinked with an azobenzyl crosslinker, that displayed pH- and enzyme-responsive properties. The swelling and drug release from hydrogel were analysed in pH 1.2, 6.5 and 7.4 buffers, and in the presence of rat caecal matter using metronidazole and mesalamine as model BCS Class I and IV drugs, respectively. Swelling studies displayed pH-responsive swelling behaviour, where swelling was maximum at pH 7.4 and minimum at pH 1.2 (69 % versus 32 %). Consequently, drug release was limited in gastric and small intestinal conditions but increased significantly when exposed to colonic conditions containing caecal matter. This system displays promising capacity for achieving colon-targeted drug delivery with enhanced dissolution of poorly water-soluble drugs for local treatment of IBD and other colon-targeted therapies.

UV polymerization fabrication method for polymer composite based optical fiber sensors

Optical fiber (OF) sensors are critical optical devices with excellent sensing capabilities and the capacity to operate in remote and hostile environments. However, integrating functional materials and micro/nanostructures into the optical fiber systems for specific sensing applications has limitations of compatibility, readiness, poor control, robustness, and cost-effectiveness. Herein, we have demonstrated the fabrication and integration of stimuli-responsive optical fiber probe sensors using a novel, low-cost, and facile 3D printing process. Thermal stimulus-response of thermochromic pigment micro-powders was integrated with optical fibers by incorporating them into ultraviolet-sensitive transparent polymer resins and then printed via a single droplet 3D printing process. Hence, the thermally active polymer composite fibers were grown (additively manufactured) on top of the commercial optical fiber tips. Then, the thermal response was studied within the temperature range of (25-35 °C) and (25-31 °C) for unicolor and dual color pigment powders-based fiber-tip sensors, respectively. The unicolor (with color to colorless transition) and dual color (with color to color transition) powders-based sensors exhibited substantial variations in transmission and reflection spectra by reversibly increasing and decreasing temperatures. The sensitivities were calculated from the transmission spectra where average change in transmission spectra was recorded as 3.5% with every 1 °C for blue, 3% for red and 1% for orange-yellow thermochromic powders based optical fiber tip sensors. Our fabricated sensors are cost-effective, reusable, and flexible in terms of materials and process parameters. Thus, the fabrication process can potentially develop transparent and tunable thermochromic sensors for remote sensing with a much simpler manufacturing process compared to conventional and other 3D printing processes for optical fiber sensors. Moreover, this process can integrate micro/nanostructures as patterns on the optical fiber tips to increase sensitivity. The developed sensors may be employed as remote temperature sensors in biomedical and healthcare applications.

Developing Transparent and Conductive PolyHEMA Gels Using Deep Eutectic Solvents

Poly(2-hydroxyethyl methacrylate) (polyHEMA) hydrogels are commonly used in biomaterials such as contact lenses. However, water evaporation from these hydrogels can cause discomfort to wearers, and the bulk polymerization method used to synthesize them often results in heterogeneous microstructures, reducing their optical properties and elasticity. In this study, we synthesized polyHEMA gels using a deep eutectic solvent (DES) instead of water and compared their properties to traditional hydrogels. Fourier-transform infrared spectroscopy (FTIR) showed that HEMA conversion in DES was faster than in water. DES gels also demonstrated higher transparency, toughness, and conductivity, along with lower dehydration, than hydrogels. The compressive and tensile modulus values of DES gels increased with HEMA concentration. A DES gel with 45% HEMA showed excellent compression-relaxation cycles and had the highest strain at break value in the tensile test. Our findings suggest that DES is a promising alternative to water for synthesizing contact lenses with improved optical and mechanical properties. Furthermore, DES gels' conduction properties may enable their application in biosensors. This study presents an innovative approach to synthesizing polyHEMA gels and provides insights into their potential applications in the biomaterials field.

Microliter Scale Synthesis of Luciferase-Encapsulated Polymersomes as Artificial Organelles for Optogenetic Modulation of Cardiomyocyte Beating

Constructing artificial systems that effectively replace or supplement natural biological machinery within cells is one of the fundamental challenges underpinning bioengineering. At the sub-cellular scale, artificial organelles (AOs) have significant potential as long-acting biomedical implants, mimicking native organelles by conducting intracellularly compartmentalized enzymatic actions. The potency of these AOs can be heightened when judiciously combined with genetic engineering, producing highly tailorable biohybrid cellular systems. Here, the authors present a cost-effective, microliter scale (10 µL) polymersome (PSome) synthesis based on polymerization-induced self-assembly for the in situ encapsulation of Gaussia luciferase (GLuc), as a model luminescent enzyme. These GLuc-loaded PSomes present ideal features of AOs including enhanced enzymatic resistance to thermal, proteolytic, and intracellular stresses. To demonstrate their biomodulation potential, the intracellular luminescence of GLuc-loaded PSomes is coupled to optogenetically engineered cardiomyocytes, allowing modulation of cardiac beating frequency through treatment with coelenterazine (CTZ) as the substrate for GLuc. The long-term intracellular stability of the luminescent AOs allows this cardiostimulatory phenomenon to be reinitiated with fresh CTZ even after 7 days in culture. This synergistic combination of organelle-mimicking synthetic materials with genetic engineering is therefore envisioned as a highly universal strategy for the generation of new biohybrid cellular systems displaying unique triggerable properties.

Degradable Polyampholytes from Radical Ring-Opening Copolymerization Enhance Cellular Cryopreservation

Macromolecular cryoprotectants based on polyampholytes are showing promise as supplemental cryoprotectants alongside conventional DMSO-based freezing. Here we exploit radical ring-opening (ter)polymerization to access ester-containing cryoprotective polyampholytes, which were shown to be degradable. Using a challenging cell monolayer cryopreservation model, the degradable polyampholytes were found to enhance post-thaw recovery when supplemented into DMSO. This demonstrates that degradable macromolecular cryoprotectants can be developed for application in biotechnology and biomedicine.

Backbone degradable poly(acrylic acid) analogue via radical ring-opening copolymerization and enhanced biodegradability

Degradable poly(acrylic acid) has been prepared via free radical ring-opening copolymerization of tert-butyl acrylate and 2-methylene-1,3-dioxepane followed by tert-butyl deprotection, under acidic conditions. The resulting degradable poly(acrylic acid) analogue possesses ester groups within the backbone, which facilitate environmental hydrolysis into short chain oligomers, which subsequently undergo biodegradation. The degradable poly(acrylic acid) reported displays a significant degree of biodegradability (27.50% in 28 days) under environmental conditions, when compared to a conventional all carbon backbone non-degradable version, which shows no biodegradability.

The usage of composite nanomaterials in biomedical engineering applications

Nanotechnology is still developing over the decades and it is commonly used in biomedical applications with the design of nanomaterials due to the several purposes. With the investigation of materials on the molecular level has increased the develop composite nanomaterials with exceptional properties using in different applications and industries. The application of these composite nanomaterials is widely used in the fields of textile, chemical, energy, defense industry, electronics, and biomedical engineering which is growing and developing on human health. Development of biosensors for the diagnosis of diseases, drug targeting and controlled release applications, medical implants and imaging techniques are the research topics of nanobiotechnology. In this review, overview of the development of nanotechnology and applications which is use of composite nanomaterials in biomedical engineering is provided.

Biomimetic Mineralization of Tannic Acid-Supplemented HEMA/SBMA Nanocomposite Hydrogels

This study developed a tannic acid (TA)-supplemented 2-hydroxyethyl methacrylate-co-sulfobetaine methacrylate (HEMA-co-SBMA) nanocomposite hydrogel with mineralization and antibacterial functions. Initially, hybrid hydrogels were synthesized by incorporating SBMA into the HEMA network and the influence of SBMA on the chemical structure, water content, mechanical properties, and antibacterial characteristics of the hybrid HEMA/SBMA hydrogels was examined. Then, nanoclay (Laponite XLG) was introduced into the hybrid HEMA/SBMA hydrogels and the effects evaluated of the nanoclay on the chemical structure, water content, and mechanical properties of these supplemented hydrogels. The 50/50 hybrid HEMA/SBMA hydrogel with 30 mg/mL nanoclay showed outstanding mechanical properties (3 MPa) and water content (60%) compared to pure polyHEMA hydrogels. TA then went on to be incorporated into these hybrid nanocomposite hydrogels and its effects investigated on biomimetic mineralization. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) showed that bone-like spheroidal precipitates with a Ca/P ratio of 1.67% were observed after 28 days within these mineralized hydrogels. These mineralized hydrogels demonstrated an almost 1.5-fold increase in compressive moduli compared to the hydrogels without mineralization. These multifunctional hydrogels display good mechanical and biomimetic properties and may have applications in bone regeneration therapies.

Phenylalanine-Tethered pH-Responsive Poly(2-Hydroxyethyl Methacrylate)

A series of pH-responsive random copolymers comprised of 2-hydroxyethyl methacrylate (HEMA) and tert-butyl carbamate (Boc)-protected phenylalanine methacryloyloxyethyl ester (Boc-Phe-EMA) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in N,N'-dimethylformamide (DMF) at 70 °C. The synthesized copolymers were comprehensively characterized using a combination of techniques, including ¹ H NMR, FT-IR spectroscopy and size exclusion chromatography (SEC). Reactivity of each monomers towards controlled radical polymerization was evaluated by determining the reactivity ratios by virtue of extended Kelen-Tüdös method at high conversions revealed the higher reactivity of non-modified HEMA (r_HEMA =1.03) in contrast to Boc-Phe-EMA (r_Boc-Phe-EMA =0.48). Furthermore, the expulsion of the Boc-groups resulted copolymers with ionizable pendant primary ammonium and hydroxyl groups. To understand the glass transition behaviours of homo- and co-polymers, differential scanning calorimetric (DSC) measurements were carried out. The effect of HEMA content on the pH-sensitivity of the copolymers in aqueous medium was investigated through turbidity measurements. Finally, the counteranion exchange from trifluoroacetate to chloride provided copolymers with enhanced water solubility and unaltered phase transition pH.

3D Particle Free Printing of Biocompatible Conductive Hydrogel Platforms for Neuron Growth and Electrophysiological Recording

Electrically conductive 3D periodic microscaffolds are fabricated using a particle-free direct ink writing approach for use as neuronal growth and electrophysiological recording platforms. A poly (2-hydroxyethyl methacrylate) (pHEMA)/pyrrole ink, followed by chemical in situ polymerization of pyrrole, enables hydrogel printing through nozzles as small as 1 μm. These conductive hydrogels can pattern complex 2D and 3D structures and have good biocompatibility with test cell cultures (~94.5% viability after 7 days). Hydrogel arrays promote extensive neurite outgrowth of cultured Aplysia californica pedal ganglion neurons. This platform allows extracellular electrophysiological recording of steady-state and stimulated electrical neuronal activities. In summation, this 3D conductive ink printing process enables preparation of biocompatible and micron-sized structures to create customized in vitro electrophysiological recording platforms.

Biocompliant Composite Au/pHEMA Plasmonic Scaffolds for 3D Cell Culture and Noninvasive Sensing of Cellular Metabolites

The field of 3D printing is an area of active research, with a substantial focus given to the design and construction of customized tools for applications in technology. There exists a particular need in these developing areas of opportunity for new multi-functional soft materials that are biologically compatible for the growth and directed culturing of cells. Herein, a composite material consisting of gold nanoparticles with useful plasmonic properties embedded within a highly hydrophilic poly-2-hydroxyethylmethacrylate matrix is described and characterized. This composite material serves dual functions as both host framework scaffold for cell lines such as pre-osteoblasts as well as a plasmonic biosensor for in situ measurements of living cells. The plasmonic properties of this system are characterized as a function of the material properties and related to compositional features of the material through a proposed light-directed mechanism. This chemistry provides a tunable, 3D printable plasmonic composite material of encapsulated gold nanoparticles in a biologically-compliant, acrylate-based hydrogel matrix. Surface-enhanced Raman scattering studies of 3D-microcultures supported by the scaffolds are carried out and the strong influence of perm-selective molecular diffusion in its analytical responses is established. Most notably, specific, largely hydrophilic, cellular metabolites are detected within the supported live cultures.

100th Anniversary of Macromolecular Science Viewpoint: Degradable Polymers from Radical Ring-Opening Polymerization: Latest Advances, New Directions, and Ongoing Challenges

Radical ring-opening polymerization (rROP) allows facile incorporation of labile groups (e.g., ester) into the main chain of vinyl polymers to obtain (bio)degradable materials. rROP has focused a lot of attention especially since the advent of reversible deactivation radical polymerization (RDRP) techniques and is still incredibly moving forward, as attested by the numerous achievements in terms of monomer synthesis, macromolecular engineering, and potential biomedical applications of the resulting degradable polymers. In the present Viewpoint, we will cover the latest progress made in rROP in the last ∼5 years, such as its recent directions, its remaining limitations, and the ongoing challenges. More specifically, this will be achieved through the three different classes of monomers that recently caught most of the attention: cyclic ketene acetals (CKA), thionolactones, and macrocyclic monomers.

Reversible-deactivation radical polymerization of cyclic ketene acetals

This review discusses the history of reversible-deactivation radical ring-opening polymerization of cyclic ketene acetals, focusing on the preparation of degradable complex polymeric architectures.

Macromolecular approach for targeted radioimmunotherapy in non-Hodgkin's lymphoma

Polymers are an attractive anchoring platform for the synthesis of radioimmunoconjugates. They enable independent control over the amount of radioisotope loading and antibody attachment, which is pivotal in developing tailorable formulations for personalised medicine. Herein, we report the synthesis of p(HEMA-ran-GMA) for the conjugation of lutetium ions and rituximab as a functional platform for radioimmunotherapy. We demonstrate the suitability of this platform using non-Hodgkin's lymphoma cells.

A Review on Styrene Substitutes in Thermosets and Their Composites

In recent decades, tremendous interest and technological development have been poured into thermosets and their composites. The thermosets and composites with unsaturated double bonds curing system are especially concerned due to their versatility. To further exploit such resins, reactive diluents (RDs) with unsaturated sites are usually incorporated to improve their processability and mechanical properties. Traditional RD, styrene, is a toxic volatile organic compound and one of the anticipated carcinogens warned by the National Institute of Health, USA. Most efforts have been conducted on reducing the usage of styrene in the production of thermosets and their composites, while very few works have systematically summarized these literatures. Herein, recent developments regarding styrene substitutes in thermosets and their composites are reviewed. Potential styrene alternatives, such as vinyl derivatives of benzene and (methyl)acrylates are discussed in details. Emphasis is focused on the strategies on developing novel RD monomers through grafting unsaturated functional groups on renewable feedstocks such as carbohydrates, lignin, and fatty acids. This review also highlights the development and characteristics of RD monomers and their influence on processability and mechanical performance of the resulting thermosets and composites.

Simulation of the Degradation of Cyclic Ketene Acetal and Vinyl-Based Copolymers Synthesized via a Radical Process: Influence of the Reactivity Ratios on the Degradability Properties

The radical copolymerization of vinyl and cyclic ketene acetal (CKA) monomers is a promising way to prepare degradable vinyl polymers. The reactivity of the comonomer pair is known to be dependent of the vinyl monomer structure that requires to play with experimental conditions (feed ratio, overall monomer conversion, etc.) to target a desired cumulative (average) copolymer composition. Even if the materials are completely degradable, there is no information about the homogeneity of the degraded products. This theoretical study, using kinetic Monte Carlo simulations, allows simulating degradation at the molecular level. It is shown that disparate reactivity ratios (styrene/CKA, etc.) and also a composition drift at high conversion can lead to an inhomogeneous degraded product compared to systems with similar reactivity ratios (vinyl ether/CKA, etc.). The use of reversible deactivation radical polymerization techniques does not influence the final degraded products and is only useful for the design of advanced macromolecular architectures before degradation.

Biomaterials for revascularization and immunomodulation after spinal cord injury

Spinal cord injury (SCI) causes immediate damage to the nervous tissue accompanied by loss of motor and sensory function. The limited self-repair competence of injured nervous tissue underscores the need for reparative interventions to recover function after SCI. The vasculature of the spinal cord plays a crucial role in SCI and repair. Ruptured and sheared blood vessels in the injury epicenter and blood vessels with a breached blood-spinal cord barrier (BSCB) in the surrounding tissue cause bleeding and inflammation, which contribute to the overall tissue damage. The insufficient formation of new functional vasculature in and near the injury impedes endogenous tissue repair and limits the prospect of repair approaches. Limiting the loss of blood vessels, stabilizing the BSCB, and promoting the formation of new blood vessels are therapeutic targets for spinal cord repair. Inflammation is an integral part of injury-mediated vascular damage, which has deleterious and reparative consequences. Inflammation and the formation of new blood vessels are intricately interwoven. Biomaterials can be effectively used for promoting and guiding blood vessel formation or modulating the inflammatory response after SCI, thereby governing the extent of damage and the success of reparative interventions. This review deals with the vasculature after SCI, the reciprocal interactions between inflammation and blood vessel formation, and the potential of biomaterials to support revascularization and immunomodulation in damaged spinal cord nervous tissue.

Introducing an attractive method for total biomimetic creation of a synthetic biodegradable bioactive bone scaffold based on statistical experimental design

A new total biomimetic technique based on both the water uptake and degradation processes is introduced in this study to provide an interesting procedure to fabricate a bioactive and biodegradable synthetic scaffold, which has a good mechanical and structural properties. The optimization of effective parameters to scaffold fabrication was done by response surface methodology/central composite design (CCD). With this method, a synthetic scaffold was fabricated which has a uniform and open-interconnected porous structure with the largest pore size of 100-200μm. The obtained compressive ultimate strength of ~35MPa and compression modulus of 58MPa are similar to some of the trabecular bone. The pore morphology, size, and distribution of the scaffold were characterized using a scanning electron microscope and mercury porosimeter. Fourier transform infrared spectroscopy, EDAX and X-ray diffraction analyses were used to determine the chemical composition, Ca/P element ratio of mineralized microparticles, and the crystal structure of the scaffolds, respectively. The optimum biodegradable synthetic scaffold based on its raw materials of polypropylene fumarate, hydroxyethyl methacrylate and nano bioactive glass (PPF/HEMA/nanoBG) as 70/30wt/wt%, 20wt%, and 1.5wt/wt% (PHB.732/1.5) with desired porosity, pore size, and geometry were created by 4weeks immersion in SBF. This scaffold showed considerable biocompatibility in the ranging from 86 to 101% for the indirect and direct contact tests and good osteoblast cell attachment when studied with the bone-like cells.

Rough Adhesive Hydrogels (RAd gels) for Underwater Adhesion

In this work, underwater adhesion is achieved between biocompatible hydrogels and a suite of substrates. Surface roughness, which is typically detrimental for adhesion in air, is shown to be beneficial for underwater adhesion. Contact between the hydrogels with macroscopically flat substrates, and the resulting nonspecific chemical interaction, is facilitated by surface roughness, which enables drainage of the lubricating fluid layer. Hydrogel composition plays an important role in tuning the gel elasticity and interaction with the substrate. Hydrogels that are adhesive on two sides are synthesized for potential use as versatile adhesives in various applications.

Fabrication of thermo-responsive cotton fabrics using poly(vinyl caprolactam-co-hydroxyethyl acrylamide) copolymer

A thermo-responsive polymer with hydrophilic to hydrophobic transition behavior, poly(vinyl caprolactam-co-hydroxyethyl acrylamide) P(VCL-co-HEAA), was prepared by copolymerization of vinyl caprolactam and N-hydroxyethyl acrylamide via free radical solution polymerization. The resulting copolymer was characterized by Fourier transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The lower critical solution temperature (LCST) of P(VCL-co-HEAA) was determined at 34.5°C. This thermo-responsive polymer was then grafted onto cotton fabrics using 1,2,3,4-butanetetracarboxylic acid (BTCA) as crosslinker and sodium hypophosphite (SHP) as catalyst. FTIR and energy dispersive X-ray spectroscopy (EDS) studies confirmed the successful grafting reaction. The modified cotton fabric exhibited thermo-responsive behavior as evidenced by water vapor permeability measurement confirming decreased permeability at elevated temperature. This is the first demonstration that a PVCL based copolymer is grafted to cotton fabrics. This study provides a new thermo-responsive polymer for fabrication of smart cotton fabrics with thermally switchable hydrophilicity.

Synthetically controlling dendrimer flexibility improves delivery of large plasmid DNA

Tools for editing the genome and epigenome have revolutionised the field of molecular biology and represent a new frontier in targeted therapeutic intervention. Although efficiencies and specificities of genome editing technologies have improved with the development of TALEs and CRISPR platforms, intracellular delivery of these larger constructs still remains a challenge using existing delivery agents. Viral vectors, including lentiviruses and adeno-associated viruses, as well as some non-viral strategies, such as cationic polymers and liposomes, are limited by packaging capacity, poor delivery, toxicity, and immunogenicity. We report a highly controlled synthetic strategy to engineer a flexible dendritic polymer using click chemistry to overcome the aforementioned delivery challenges associated with genome engineering technologies. Using a systematic approach, we demonstrate that high transfection efficiencies and packaging capacity can be achieved using this non-viral delivery methodology to deliver zinc fingers, TALEs and CRISPR/dCas9 platforms.

Micropatterned Hydrogel Surface with High-Aspect-Ratio Features for Cell Guidance and Tissue Growth

Surface topography has been introduced as a new tool to coordinate cell selection, growth, morphology, and differentiation. The materials explored so far for making such structural surfaces are mostly rigid and impermeable. Hydrogel, on the other hand, was proved a better synthetic media for cell culture because of its biocompatibility, softness, and high permeability. Herein, we fabricated a poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel substrate with high-aspect-ratio surface microfeatures. Such structural surface could effectively guide the orientation and shape of human mesenchymal stem cells (HMSCs). Notably, on the flat hydrogel surface, cells rounded up, whereas on the microplate patterned hydrogel surface, cells elongated and aligned along the direction parallel to the plates. The microplates were 2 μm thick, 20 μm tall, and 10-50 μm wide. The interplate spacing was 5-15 μm, and the intercolumn spacing was 5 μm. The elongation of cell body was more pronounced on the patterns with narrower interplate spacing and wider plates. The cells behaved like soft solid. The competition between surface energy and elastic energy defined the shape of the cells on the structured surfaces. The soft permeable hydrogel scaffold with surface structures was also demonstrated as being viable for long-term cell culture, and could be used to generate interconnected tissues with finely tuned cell morphology and alignment across a few centimeter sizes.

A ring to rule them all: a cyclic ketene acetal comonomer controls the nitroxide-mediated polymerization of methacrylates and confers tunable degradability

2-Methylene-4-phenyl-1,3-dioxolane (MPDL) was successfully used as a controlling comonomer in NMP with oligo(ethylene glycol) methyl ether methacrylate (MeOEGMA) to prepare well-defined and degradable PEG-based P(MeOEGMA-co-MPDL) copolymers. The level of ester group incorporation is controlled, leading to reductions in molecular weight of up to 95% on hydrolysis. Neither the polymer nor its degradation products displayed cytoxicity. The method was also successfully applied to methyl methacrylate.

Controlling fungal biofilms with functional drug delivery denture biomaterials

Candida-associated denture stomatitis (CADS), caused by colonization and biofilm-formation of Candida species on denture surfaces, is a significant clinical concern. We show here that modification of conventional denture materials with functional groups can significantly increase drug binding capacity and control drug release rate of the resulting denture materials for potentially managing CADS. In our approach, poly(methyl methacrylate) (PMMA)-based denture resins were surface grafted with three kinds of polymers, poly(1-vinyl-2-pyrrolidinone) (PNVP), poly(methacrylic acid) (PMAA), and poly(2-hydroxyethyl methacrylate) (PHEMA), through plasma-initiated grafting polymerization. With a grafting yield as low as 2 wt%, the three classes of new functionalized denture materials showed significantly higher drug binding capacities toward miconazole, a widely used antifungal drug, than the original PMMA denture resin control, leading to sustained drug release and potent biofilm-controlling effects against Candida. Among the three classes of functionalized denture materials, PNVP-grafted resin provided the highest miconazole binding capability and the most powerful antifungal and biofilm-controlling activities. Drug binding mechanisms were studied. These results demonstrated the importance of specific interactions between drug molecules and functional groups on biomaterials, shedding lights on future design of CADS-managing denture materials and other related devices for controlled drug delivery.

New unsaturated copolyesters based on 2,5-furandicarboxylic acid and their crosslinked derivatives

The synthesis and characterisation of a novel family of unsaturated polyesters (UPs) and their crosslinked resins (UPRs), based on 2,5-furandicarboxylic acid (FDCA), are reported.

Efficient synthesis of 2-methylene-4-phenyl-1,3-dioxolane, a cyclic ketene acetal for controlling the NMP of methyl methacrylate and conferring tunable degradability

The efficient and reliable synthesis of 2-methylene-4-phenyl-1,3-dioxolane (MPDL) was reported and MPDL was used as a controlling comonomer for nitroxide-mediated polymerization of methyl methacrylate to give degradable copolymers.

Encapsulation of polyphenols into pHEMA e-spun fibers and determination of their antioxidant activities

This study reports on the development of electrospun poly(2-hydroxyethyl methacrylate) (pHEMA) fibers loaded with synthetic and natural antioxidants in the form of selected types of polyphenols such as vanillic, gallic, syringic acids, catechin or natural spruce bark extract to investigate their release behavior in terms of antioxidant activities. Homogenous fiber morphologies were obtained at specified concentration ranges of pHEMA within the spinning solutions, exhibiting fiber diameters in the range from 0.5±0.1 μm to 1.9±0.5 μm. The addition of polyphenols resulted in an increase of fiber diameters with increasing concentration of additives. This is attributed to the effect of hydrogen bonding between the active ingredients and the polymeric matrix, increasing shear viscosities and thus hindering effective drawing processes during fiber formation. Polyphenol release measurement gave high release rates in a first phase followed by a smooth release at long term. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, used to monitor antioxidant activity, showed that polyphenols had retained their activity after incorporation into the pHEMA nanofibers. Furthermore, it was demonstrated that the encapsulation of polyphenols in pHEMA nanofibers can delay to a high extent their degradation induced by environmental factors.

Nitroxide-mediated radical ring-opening copolymerization: chain-end investigation and block copolymer synthesis

Well-defined, degradable copolymers are successfully prepared by nitroxide-mediated radical ring opening polymerization (NMrROP) of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) or methyl methacrylate (MMA), a small amount of acrylonitrile (AN) and cyclic ketene acetals (CKAs) of different structures. Phosphorous nuclear magnetic resonance allows in-depth chain-end characterization and gives crucial insights into the nature of the copoly-mer terminal sequences and the living chain fractions. By using a small library of P(OEGMA-co-AN-co-CKA) and P(MMA-co-AN-co-CKA) as macroinitiators, chain extensions with styrene are performed to furnish (amphiphilic) block copolymers comprising a degradable segment.