Amphiphilic polymers are increasingly applied in the detergent-free isolation and functional studies of membrane proteins. However, the carboxylate group present in the structure of many popular variants, such as styrene-maleic acid (SMA) copolymers, brings limitations in terms of polymer sensitivity to precipitation at acidic pH or in the presence of divalent metal cations. Herein, we addressed this problem by replacing carboxylate with the more acidic sulfonate groups. To this end, we synthesized a library of amphiphilic poly[styrene--(sodium 4-styrene sulfonate)] copolymers (termed SSS), differing in their molecular weight and overall polarity. Using model cell membranes (Jurkat), we identified two copolymer compositions (SSS-L30 and SSS-L36) that solubilized membranes to an extent similar to SMA. Interestingly, the density gradient ultracentrifugation/SDS-PAGE/Western blotting analysis of cell lysates revealed a distribution of studied membrane proteins in the gradient fractions that was different than for SMA-solubilized membranes. Importantly, unlike SMA, the SSS copolymers remained soluble at low pH and in the presence of Mg ions. Additionally, the solubilization of DMPC liposomes by the lead materials was studied by turbidimetry, DLS, SEC, and high-resolution NMR, revealing, for SSS-L36, the formation of stable particles (nanodiscs), facilitated by the direct hydrophobic interaction of the copolymer phenyls with lipid acyl chains.

The global spread of SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) has caused the loss of many human lives and severe economic losses. SARS-CoV-2 mediates its infection in humans via the spike glycoprotein. The receptor binding domain of the SARS-CoV-2 spike protein binds to its cognate receptor, angiotensin converting enzyme-2 (ACE2) to initiate viral entry. In this study, we examine how polymer modification of the spike protein receptor binding domain impacts binding to ACE2. The horseradish peroxidase conjugated receptor binding domain was modified with a range of polymers including hydrophilic -dimethylacrylamide, hydrophobic -isopropylacrylamide, cationic 3-(-dimethylamino)propylacrylamide, and anionic 2-acrylamido-2-methylpropane sulfonic acid polymers. The effect of polymer chain length was observed using -dimethylacrylamide polymers with degrees of polymerization of 5, 10 and 25. Polymer conjugation of the receptor binding domain significantly reduced the interaction with ACE2 protein, as determined by an enzyme-linked immunosorbent assay. Stability analysis showed that these conjugates remained highly stable even after seven days incubation at physiological temperature. Hence, this study provides a detailed view of the effect specific type of modification using a library of polymers with different functionalities in interrupting RBD-ACE2 interaction.

A new coronavirus disease, SARS-CoV-2, has spread into a global pandemic in December 2019. Since no specific therapeutic drugs for treating COVID-19 have been approved by FDA, recent studies suggest that the known antimalarial quinine and its derivatives (chloroquine and hydroxychloroquine) inhibit receptor binding of the viral particles and inhibits the strong "cytokine storm", which is the main cause of death among infected patients. In particular, the natural alkaloid quinine has shown to possess a better safety profile and greater tolerability compared to its derivatives. Dosage optimization of quinine is still necessary as the currently available dosage forms have controversial pharmacokinetics and safety profiles. Therefore, repurposing quinine dosage forms to improve its pharmacokinetics and safety profile may be necessary to support its use against SARS-CoV-2. In this context, biodegradable/biocompatible polymeric nanoparticles may provide a safe site-specific and controlled quinine delivery, reducing the frequency of drug administration and the dose. In this study, a full atomistic molecular dynamics simulation approach has been used to investigate the use of poly-(glycolic acid) and poly-(lactic acid) and their copolymer poly-(lactic-co-glycolic acid) as potential delivery systems for lipophilic quinine to get insights into the mechanism of quinine encapsulation and release at the atomic/molecular level.

Polymer micelles, used extensively as vehicles in the delivery of active pharmaceutical ingredients, represent a versatile polymer architecture in drug delivery systems. We hypothesized that degree of crosslinking in the hydrophobic core of amphiphilic block copolymer micelles could be used to tune the rate of release of the biological signaling gas (gasotransmitter) hydrogen sulfide (HS), a potential therapeutic. To test this hypothesis, we first synthesized amphiphilic block copolymers of the structure PEG--P(FBEA) (PEG = poly(ethylene glycol), FBEA = 2-(4-formylbenzoyloxy)ethyl acrylate). Using a modified arm-first approach, we then varied the crosslinking percentage in the core-forming block addition of a alkanediyl bis(hydroxylamine) crosslinking agent. We followed incorporation of the crosslinker by H NMR spectroscopy, monitoring the appearance of the oxime signal resulting from reaction of pendant aryl aldehydes on the block copolymer with hydroxylamines on the crosslinker, which revealed crosslinking percentages of 5, 10, and 15%. We then installed HS-releasing -aroylthiooxime (SATO) groups on the crosslinked polymers, yielding micelles with SATO units in their hydrophobic cores after self-assembly in water. HS release studies in water, using cysteine (Cys) as a trigger to induce HS release from the SATO groups in the micelle core, revealed increasing half-lives of HS release, from 117 ± 6 min to 210 ± 30 min, with increasing crosslinking density in the micelle core. This result was consistent with our hypothesis, and we speculate that core crosslinking limits the rate of Cys diffusion into the micelle core, decreasing the release rate. This method for tuning the release of covalently linked small molecules through modulation of micelle core crosslinking density may extend beyond HS to other drug delivery systems where precise control of release rate is needed.

Protein storage and transport is essential to deliver therapies (biologics), enzymes for biotechnological applications, and underpins fundamental structural and molecular biology. To enable proteins to be stored and transported it is often essential to freeze them, requiring cryoprotectants such as glycerol or trehalose. Here we explore the mechanisms by which poly(vinyl alcohol), PVA, a potent ice recrystallisation inhibitor protects proteins during freeze/thaw to enable solvent-free cryopreservation with a focus on comparing mixing, verses polymer-protein conjugation. A panel of poly(vinyl alcohol)s are investigated including commercial, well-defined (from RAFT), and PVA-protein conjugates, to map out PVA's efficacy. Enzymatic activity recovery of lactate dehydrogenase was found to correlate with post-thaw aggregation state (less aggregated protein had greater activity), which was modulated by PVA's ice recrystallisation inhibition activity. This macromolecular cryoprotectant matched the performance of glycerol, but at lower additive concentrations (as low as 1 mg.mL). It was also demonstrated that storage at -20 °C, rather than -80 °C was possible using PVA as a cryoprotectant, which is not possible with glycerol storage. A second protein, green-fluorescent protein (GFP), was used to enable screening of molecular weight effects and to obtain PVA-GFP bioconjugates. It was observed that covalent attachment of RAFT-derived PVA showed superior cryoprotectant activity compared to simple mixing of the polymer and protein. These results show that PVA is a real alternative to solvent-based protein storage with potential in biotechnology, food and therapeutics. PVA is already approved for many biomedical applications, is low cost and available on a large scale, making it an ideal cryoprotectant formulation enhancer.

The incorporation of thiourethane-based oligomeric additives into resin composite formulations leads to improvement in mechanical properties and reduction in polymerization stress, but may increase viscosity. The objective of this study was to functionalize filler particle surfaces with thiourethane silane molecules and determine the impact of the inorganic filler loading and surface treatment on the behavior of experimental resin composites with systematically-varied organic matrices.

Mitogen-activated protein kinases (MAPKs), including c-Jun N-terminal kinase (JNK), play important role in the regulation of pro-inflammatory cytokine secretion and signaling cascades. Therefore, JNKs are key targets for the treatment of cytokine/JNK-driven diseases. Herein, we developed electrospray poly(lactic-co-glycolic acid) (PLGA) microparticles doped with novel JNK inhibitor 11-indeno[1,2-]quinoxalin-11-one oxime (IQ-1). Optimized electrospray parameters allowed us to produce IQ-1-doped microparticles with round shape, smooth and non-porous surface, and mean diameter of 0.9-1.3 μm. We have shown that IQ-1 was well integrated into the polymer matrix and had a prolonged release in two steps via non-Fickian release. The fabricated particles doped with IQ-1 exhibited anti-inflammatory effects, as indicated by inhibited neutrophil activation and cytokine secretion by human monocytic MonoMac-6 cells. Overall, our study demonstrates that PLGA microparticles doped with a novel JNK inhibitor (IQ-1) could be a promising delivery system for treatment of JNK-mediated diseases.

Electrospun nanofibers have been found in many applications such as air/water filtration, performance apparel, drug delivery, and scaffold for tissue engineering and started to be integrated in commercial products, which leads to their exposure to environment. Electrospun nanofibrous material is a relatively new material to microorganism in nature and little is known about the biological implication of interactions between electrospun nanofibrous mats and cellular fungal cells. Herein the interaction between electrospun polyacrylonitrile (ESPAN) nanofibrous mat and representative non-pathogenic/pathogenic cellular yeasts ( and ) was investigated. It is demonstrated for the first time that when these cellular yeasts, species of the kingdom fungi, were exposed to ESPAN nanofibrous mat, they exhibited lower growth rate, radical change to morphology, and reduced viability without presence of any chemical antifungal agent. These responses were distinct from the cellular interactions with other forms of PAN materials (e.g. solid film or microfibrous mat). Exploration of mechanism indicated that the interaction between yeast cell and electrospun nanofibrous mat is a complex phenomenon in which both nanofibrous morphology and fiber surface composition/property play significant roles. The inherent anti-yeast and potential anti-fungal functionality of ESPAN nanofibrous mat may make an immediate impact on environmental microorganism and could also benefit the next-generation material design to control microbial growth through solely physical contact.

Medical adhesives that are strong, easy to apply and biocompatible are promising alternatives to sutures and staples in a large variety of surgical and clinical procedures. Despite progress in the development and regulatory approval of adhesives for use in the clinic, adhesion to wet tissue remains challenging. Marine organisms have evolved a diverse set of highly effective wet adhesive approaches that have inspired the design of new medical adhesives. Here we provide an overview of selected marine animals and their chemical and physical adhesion strategies, the state of clinical translation of adhesives inspired by these organisms, and target applications where marine-inspired adhesives can have a significant impact. We will focus on medical adhesive polymers inspired by mussels, sandcastle worms, and cephalopods, emphasize the history of bioinspired medical adhesives from the peer reviewed and patent literature, and explore future directions including overlooked sources of bioinspiration and materials that exploit multiple bioinspired strategies.

Membrane mimetics are essential to study the structure, dynamics and function of membrane-associated proteins by biophysical and biochemical approaches. Among various membrane mimetics that have been developed and demonstrated for studies on membrane proteins, lipid nanodiscs are the latest developments in the field and are increasingly used for various applications. While lipid-nanodiscs can be formed using an amphipathic membrane scaffold protein (MSP), peptide, or synthetic polymer, the synthetic polymer based nanodiscs exhibit unique advantages because of the ability to functionalize them for various applications. In addition to the use of synthetic polymers to extract membrane proteins directly from the cell membranes, recent advances in the development of polymers used for nanodiscs formation are attracting new attention to the field of nanodiscs technology. Here we review the developments of novel polymer modifications that overcome the current limitations and enhance the applications of polymer based nanodiscs to a wider variety of biophysical techniques used to study membrane proteins. A summary of the functionalization of poly(Styrene-co-Maleic Acid), SMA, polymers developed by our research and their advantages are also covered in this review article.

Peptide based-vaccines are becoming one of the most widely investigated prophylactic and therapeutic health care interventions against a variety of diseases, including cancer. However, the lack of a safe and highly efficient adjuvant (immune stimulant) is regarded as the biggest obstacle to vaccine development. The incorporation of a peptide antigen in a nanostructure-based delivery system was recently shown to overcome this obstacle. Nanostructures are often formed from antigens conjugated to molecules such as polymers, lipids, and peptide, with the help of self-assembly phenomenon. This review describes the application of self-assembly process for the production of peptide-based vaccine candidates and the ability of these nanostructures to stimulate humoral and cellular immune responses.

An 80-membered library of gels composed of monofunctional 2-ethyl-2-oxazoline and 2-nonyl-2-oxazoline and one of four selected difunctional 2-oxazolines (containing either ether or ester bonds) were synthesized by microwave-assisted ring-opening polymerizations. The difunctional 2-oxazolines were prepared from the thiol-ene reaction of glycol dimercaptoacetate or 2,2'-(ethylenedioxy)diethanethiol and 2-but-3'-enyl-2-oxazoline or 2-dec-9'-enyl-2-oxazoline. 53 of the gels exhibited glass-transition temperatures, which ranged from -5.9 to 45.3 °C. 13 Derivatives exhibited glass-transition temperatures in the range from 20 to 30 °C, which renders them stiff at room temperature and flexible at body temperature. The gels that did not contain any 2-ethyl-2-oxazoline acted as lipogels, whereas the gels that did not contain any 2-nonyl-2-oxazoline acted as hydrogels; all other gels may be classified as amphigels. The swelling degrees were measured by gravimetry and maximum swelling degrees of 6 (in water) were observed for the gels with the lowest degrees of crosslinking. In a second approach, the synthesis of crosslinked networks had been achieved by performing the polymeranalogous thiol-ene reaction of copoly(2-oxazoline)s containing olefinic side-chains and glycol dimercaptoacetate. This soft strategy enabled the straightforward loading of such gels with active pharmaceutical ingredients without altering them. This method delivered gels with selected composition exhibiting a targeted disc-shape and loaded with active pharmaceutical ingredients from one-step syntheses. The maximum swelling degrees of these specimens were found to be in accordance with the ones from the first route investigated. Preliminary degradation studies were performed at 25 °C; these types of gels were found to be degraded in alkaline media as well as by esterases.

Polyethylene glycol (PEG) polymers are currently used in a variety of medical formulations to reduce toxicity, minimize immune interactions and improve pharmacokinetics. Despite its widespread use however, the presence of anti-PEG antibodies indicates that this polymer has the potential to be immunogenic and antigenic. Here we present an alternative polymer, poly(2-oxazoline) (POx) for stealth applications, specifically shielding of a proteinaceous nanoparticle from recognition by the immune system. Tobacco mosaic virus (TMV) was used as our testbed due to its potential for use as a nanocarrier for drug delivery and molecular imaging applications.

Here, we describe novel polyion complex (PIC) particles for the delivery of Polymyxin B (Pol-B), an antimicrobial peptide currently used in the clinic as a last resort antibiotic against multidrug-resistant gram-negative bacteria. A range of conditions for the controlled assembly of Pol-B with poly(styrene sulphonate) (PSS) has been identified which let us prepare stable colloidal PIC particles. This way, PIC particles containing different Pol-B:PSS ratios have been prepared and their stability under simulated physiological conditions (. pH, osmotic pressure and temperature) characterised. Furthermore, preliminary evaluation of the antimicrobial activity of these Pol-B containing PIC particles has been performed, by monitoring their effect on the growth of , an opportunistic gram-negative bacterium.

Oppositely charged polyions can self-assemble in solution to form colloidal polyion complex (PIC) particles. Such nanomaterials can be loaded with charged therapeutics such as DNA, drugs or probes for application as novel nanomedicines and chemical sensors to detect disease markers. A comprehensive discussion of the factors affecting PIC particle self-assembly and their response to physical and chemical stimuli in solution is described herein. Finally, a collection of key examples of polyionic nanoparticles for biomedical applications is discussed to illustrate their behaviour and demonstrate the potential of PIC nanoparticles in medicine.

Due to their hydrophilic, biocompatible, and highly tunable nature, hydrogel materials have attracted strong interest in the recent years for numerous biotechnological applications. In particular, their solution-like environment and non-fouling nature in complex biological samples render hydrogels as ideal substrates for biosensing applications. Hydrogel coatings, and later, gel dot surface microarrays, were successfully used in sensitive nucleic acid assays and immunoassays. More recently, new microfabrication techniques for synthesizing encoded particles from hydrogel materials have enabled the development of hydrogel-based suspension arrays. Lithography processes and droplet-based microfluidic techniques enable generation of libraries of particles with unique spectral or graphical codes, for multiplexed sensing in biological samples. In this review, we discuss the key questions arising when designing hydrogel particles dedicated to biosensing. How can the hydrogel material be engineered in order to tune its properties and immobilize bioprobes inside? What are the strategies to fabricate and encode gel particles, and how can particles be processed and decoded after the assay? Finally, we review the bioassays reported so far in the literature that have used hydrogel particle arrays and give an outlook of further developments of the field.

Due to their high water content and diffusivity of nutrients and biomolecules, hydrogels are very attractive as a matrix for growth factor immobilization and delivery of cells to the site of regeneration in tissue engineering. The formation of micellar structures at the nanoscale in hydrogels alters the spatial distribution of the reactive groups and affects the rate and extent of crosslinking and mechanical properties of the hydrogel. Further, the degradation rate of a hydrogel is strongly affected by the proximity of water molecules to the hydrolytically degradable segments at the nanoscale. The objective of this review is to summarize the unique properties of micellar hydrogels with a focus on our previous work on star polyethylene glycol (PEG) macromonomers chain extended with short aliphatic hydroxy acid (HA) segments (SPEXA hydrogels). Micellar SPEXA hydrogels have faster gelation rates and higher compressive moduli compared to their non-micellar counterpart. Owing to their micellar structure, SPEXA hydrogels have a wide range of degradation rates from a few days to many months as opposed to non-degradable PEG gels while both gels possess similar water contents. Furthermore, the viability and differentiation of mesenchymal stem cells (MSCs) is enhanced when the cells are encapsulated in degradable micellar SPEXA gels compared with those cells encapsulated in non-micellar PEG gels.

Multiply responsive protein nanoparticles are interesting for a variety of applications. Herein, we describe the synthesis of a vault nanoparticle that responds to both temperature and pH. Specifically, poly(-isopropylacrylamide--acrylic acid) with a pyridyl disulfide end group was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymer had a lower critical solution temperature (LCST) of 31.9 °C at pH 5, 44.0 °C at pH 6 and above 60 °C at pH 7. The polymer was conjugated to human major vault protein (hMVP), and the resulting nanoparticle was analyzed by UV-Vis, dynamic light scattering (DLS) and electron microscopy. The data demonstrated that poly(-isopropylacrylamide--acrylic acid)-vault conjugate did not respond to temperatures below 60 °C at pH 7, while the nanoparticles reversibly aggregated at pH 6. Furthermore, it was shown that the vault nanoparticle structure remained intact for at least three heat and cooling cycles. Thus, these dually responsive nanoparticles may serve as a platform for drug delivery and other applications.

This work presents an approach to extend the period for phase separation, independent of temperature, in ambient phase-separating photopolymerizations based on the copolymerization of structurally similar mono- and di-vinyl monomers. Copolymer resins composed of triethylene glycol dimethacrylate (TEGDMA) and ethylene glycol methyl ether methacrylate (EGMEMA) were modified with a thermoplastic prepolymer, poly(butyl methacrylate). With increasing EGMEMA modification into the bulk TEGDMA resin, there is a decrease in the initial reaction rate, which increases the time for development of compositionally different phases prior to network gelation. The period between phase separation and gelation was probed through optical and rheological measurements, and it was extended from 22 s in a TEGDMA resin to 69 s in a TEGDMA:EGMEMA copolymer, allowing these materials to be processed under a wide range of UV-irradiation intensities (300 µW cm - 100 mW cm), which provided an additional degree of control over the resulting phase separated domain size and morphology.

Poly(ethylene glycol) (PEG)-protein therapeutics exhibit enhanced pharmacokinetics, but have drawbacks including decreased protein activities and polymer accumulation in the body. Therefore a major aim for second-generation polymer therapeutics is to introduce degradability into the backbone. Herein we describe the synthesis of poly(poly(ethylene glycol methyl ether methacrylate)) (pPEGMA) degradable polymers with protein-reactive end-groups via reversible addition-fragmentation chain transfer (RAFT) polymerization, and the subsequent covalent attachment to lysozyme through a reducible disulfide linkage. RAFT copolymerization of cyclic ketene acetal (CKA) monomer 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) with PEGMA yielded two polymers with number-average molecular weight ( ) (GPC) of 10.9 and 20.9 kDa and molecular weight dispersities (Ð) of 1.34 and 1.71, respectively. Hydrolytic degradation of the polymers was analyzed by H-NMR and GPC under basic and acidic conditions. The reversible covalent attachment of these polymers to lysozyme, as well as the hydrolytic and reductive cleavage of the polymer from the protein, was analyzed by gel electrophoresis and mass spectrometry. Following reductive cleavage of the polymer, an increase in activity was observed for both conjugates, with the released protein having full activity. This represents a method to prepare PEGylated proteins, where the polymer is readily cleaved from the protein and the main chain of the polymer is degradable.

Here, we report the synthesis and characterization of a novel 4-arm poly(lactic acid urethane)-maleate (4PLAUMA) elastomer and its composites with nano-hydroxyapatite (nHA) as potential weight-bearing composite. The 4PLAUMA/nHA ratios of the composites were 1:3, 2:5, 1:2 and 1:1. FTIR and NMR characterization showed urethane and maleate units integrated into the PLA matrix. Energy dispersion and Auger electron spectroscopy confirmed homogeneous distribution of nHA in the polymer matrix. Maximum moduli and strength of the composites of 4PLAUMA/nHA, respectively, are 1973.31 ± 298.53 MPa and 78.10 ± 3.82 MPa for compression, 3630.46 ± 528.32 MPa and 6.23 ± 1.44 MPa for tension, 1810.42 ± 86.10 MPa and 13.00 ± 0.72 for bending, and 282.46 ± 24.91 MPa and 5.20 ± 0.85 MPa for torsion. The maximum tensile strains of the polymer and composites are in the range of 5% to 93%, and their maximum torsional strains vary from 0.26 to 0.90. The composites exhibited very slow degradation rates in aqueous solution, from approximately 50% mass remaining for the pure polymer to 75% mass remaining for composites with high nHA contents, after a period of 8 weeks. Increase in ceramic content increased mechanical properties, but decreased maximum strain, degradation rate, and swelling of the composites. Human bone marrow stem cells and human endothelial cells adhered and proliferated on 4PLAUMA films and degradation products of the composites showed little-to-no toxicity. These results demonstrate that novel 4-arm poly(lactic acid urethane)-maleate (4PLAUMA) elastomer and its nHA composites may have potential applications in regenerative medicine.