Cell membrane-inspired phospholipid polymers for developing medical devices with excellent biointerfaces

Quantifying Phospholipids in Organic Samples Using a Hydrophilic Interaction Liquid Chromatography-Inductively Coupled Plasma High-Resolution Mass Spectrometry (HILIC-ICP-HRMS) Method

In this study, a novel method using hydrophilic interaction liquid chromatography (HILIC) coupled with inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) was introduced for the quantification of phospholipids in oil samples. The method employed a bridged ethyl hybrid (BEH) stationary phase HILIC column with a tetrahydrofuran (THF)/water mobile phase, enhancing the solubility and detection of phospholipids. During the study, a gradient/matrix effect on ICP-HRMS sensitivity was observed and successfully compensated for experimentally, ensuring reliable quantification results. This approach has proven effective for a wide range of different oil samples including vegetable oils, animal fats, and phospholipid supplements. Notably, this method allowed the direct quantification of phospholipids in oil samples, bypassing the need for prior sample preparation methods, such as solid phase extraction (SPE), thereby streamlining the analytical process. The precision, accuracy, and reduced need for extensive sample preparation offered by this method mark a significant advancement in lipids analysis. Its robustness and broad applicability have substantial implications for industries such as food and renewable energy production, where both efficient and accurate lipid identification and quantification are crucial.

A Visual Distance-Based Capillary Immunoassay Using Biomimetic Polymer Nanoparticles for Highly Sensitive and Specific C-Reactive Protein Quantification

The low-cost daily monitoring of C-reactive protein (CRP) levels is crucial for screening acute inflammation or infections as well as managing chronic inflammatory diseases. In this study, we synthesized novel 2-Methacryloyloxy ethyl phosphorylcholine (MPC)-based biomimetic nanoparticles with a large surface area to develop a visual CRP-quantification assay using affordable glass capillaries. The PMPC nanoparticles, synthesized via reflux precipitation polymerization, demonstrated multivalent binding capabilities, enabling rapid and specific CRP capture. In the presence of CRP, PMPC nanoparticles formed sandwich structures with magnetic nanoparticles functionalized with CRP antibodies, thereby enhancing detection sensitivity and specificity. These sandwich complexes were magnetically accumulated into visible and quantifiable stacks within the glass capillaries, allowing for the rapid, sensitive, and specific quantification of CRP concentrations with a detection limit of 57.5 pg/mL and a range spanning from 0 to 5000 ng/mL. The proposed visual distance-based capillary biosensor shows great potential in routine clinical diagnosis as well as point-of-care testing (POCT) in resource-limited settings.

Comparison of complement consumption and platelet accumulation between membrane oxygenators coated with a polymer or heparin

INTRODUCTION

The membrane oxygenator in extracorporeal circulation circuits is coated with acrylate-copolymer (ACP) or immobilized heparin (IHP) to enhance hemocompatibility. To evaluate the relative features of both coatings, we compared blood components circulated in the circuits with ACP-and IHP-coated membranes in vitro using whole human blood.

METHODS

Whole human blood was heparinized and circulated in two experimental circuits with an ACP-coated reservoir, tubes, and an ACP- or IHP-coated membrane. Platelet (PLT) counts and the amount of total protein (TP), complement component 3 (C3), and complement component 4 (C4) were measured at 0, 8, 16, 24, and 32 h in each experiment (n = 5).

RESULTS

The PLT count at 0-h circulation was lower in the IHP-coated than in the ACP-coated circuits (p = 0.034); however, no significant difference was observed at other time points. Reduction in TP at 8-h and 16-h circulation and in C3 at 32-h circulation was lesser in the ACP-coated than in the IHP-coated circuits (p = 0.004, 0.034, and 0.027, respectively); reduction in TP and C3 at other time points and C4 at each time point was not significantly different. There were significant interactions between coating type and circulation duration in the PLT, TP, and C3 transitions (p = 0.008, 0.020, and 0.043, respectively).

CONCLUSIONS

Our findings suggest that ACP-coated membranes can prevent the initial drop in PLT count and C3 consumption over 32 h, whereas IHP-coated membranes could not prevent this drop in extracorporeal circulation. Therefore, ACP-coated membranes are suitable for short- and long-term extracorporeal life support.

Preparation of Water-Soluble Polyion Complex (PIC) Micelles with pH-Responsive Carboxybetaine Block

A dual zwitterionic diblock copolymer (M100C100) consisting of poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC, M) and poly(3-((2-(methacryloyloxy)ethyl) dimethylammonio) propionate) (PCBMA, C) is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. A double hydrophilic diblock copolymer (M100S100) consist of PMPC and anionic poly(3-sulfopropyl methacrylate potassium salt) (PMPS, S) is synthesized via RAFT. The degrees of polymerization of each block are 100. The charges of PMPC are neutralized intramolecularly. At neutral pH, the charges in PCBMA are also neutralized intramolecularly due to its carboxybetaine structure. Under acidic conditions, PCBMA exhibits polycation behavior as the pendant carboxy groups become protonated, forming cationic tertiary amine groups. PMPS shows permanent anionic nature independent of pH. Charge neutralized mixture of cationic M100C100 and anionic M100S100 in acidic aqueous solution forms water-soluble polyion complex (PIC) micelle owing to electrostatic attractive interactions. The core is composed of the cationic PCBMA and anionic PMPS blocks, with the PMPC blocks serving as shells that covered the core surface, forming spherical core-shell PIC micelles. Above pH 4 the pendant carboxy groups in PCBMA undergo deprotonation, transitioning to a zwitterionic state, thereby eliminating the cationic charge in PCBMA. Therefore, above pH 4 the PIC micelles are dissociated due to the disappearance of the charge interactions.

Rationale Design for Anchoring Pendant Groups of Zwitterionic Polymeric Medical Coatings

A biocompatible and antifouling polymeric medical coating was developed through rational design for anchoring pendant groups for the modification of stainless steel. Zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) was copolymerized individually with three anchoring monomers of carboxyl acrylamides with different alkyl spacers, including acryloylglycine (2-AE), 6-acrylamidohexanoic acid (6-AH), and 11-acrylamidoundecanoic acid (11-AU). The carboxylic acid groups are responsible for the stable grafting of copolymers onto stainless steel via a coordinative interaction with metal oxides. Due to hydrophobic interaction and hydrogen bonding, the anchoring monomers enable the formation of self-assembling structures in solution and at a metallic interface, which can play an important role in the thin film formation and functionality of the coatings. Therefore, surface characterizations of anchoring monomers on stainless steel were conducted to analyze the packing density and strength of the intermolecular hydrogen bonds. The corresponding copolymers were synthesized, and their aggregate structures were assessed, showing micelle aggregation for copolymers with higher hydrophobic compositions. The synergistic effects of inter/intramolecular interactions and hydrophobicity of the anchoring monomers result in the diversity of the thickness, surface coverage, wettability, and friction of the polymeric coatings on stainless steel. More importantly, the antifouling properties of the coatings against bacteria and proteins were strongly correlated to thin film formation. Ultimately, the key lies in deciphering the molecular structure of the anchoring pendants in thin film formation and assessing the effectiveness of the coatings, which led to the development of medical coatings through the graft-onto approach.

Long-Term Evaluation of Inserted Nanocomposite Hydrogel-Based Phosphorescent Oxygen Biosensors: Evolution of Local Tissue Oxygen Levels and Foreign Body Response

Phosphorescence-based oxygen-sensing hydrogels are a promising platform technology for an upcoming generation of insertable biosensors that are smaller, softer, and potentially more biocompatible than earlier designs. However, much remains unknown about their long-term performance and biocompatibility in vivo. In this paper, we design and evaluate a range of hydrogel sensors that contain oxygen-sensitive phosphors stabilized by micro- and nanocarrier systems. These devices demonstrated consistently good performance and biocompatibility in young adult rats for over three months. This study thoroughly establishes the biocompatibility and long-term suitability of phosphorescence lifetime sensors in vivo, providing the groundwork for expansion of this platform technology into a family of small, unobtrusive biosensors for a range of clinically relevant metabolites.

Ionic Liquid Interface as a Cell Scaffold

In sharp contrast to conventional solid/hydrogel platforms, water-immiscible liquids, such as perfluorocarbons and silicones, allow the adhesion of mammalian cells via protein nanolayers (PNLs) formed at the interface. However, fluorocarbons and silicones, which are typically used for liquid cell culture, possess only narrow ranges of physicochemical parameters and have not allowed for a wide variety of cell culturing environments. In this paper, it is proposed that water-immiscible ionic liquids (ILs) are a new family of liquid substrates with tunable physicochemical properties and high solvation capabilities. Tetraalkylphosphonium-based ILs are identified as non-cytotoxic ILs, whereon human mesenchymal stem cells are successfully cultured. By reducing the cation charge distribution, or ionicity, via alkyl chain elongation, the interface allows cell spreading with matured focal contacts. High-speed atomic force microscopy observations of the PNL formation process suggest that the cation charge distribution significantly altered the protein adsorption dynamics, which are associated with the degree of protein denaturation and the PNL mechanics. Moreover, by exploiting dissolution capability of ILs, an ion-gel cell scaffold is fabricated. This enables to further identify the significant contribution of bulk subphase mechanics to cellular mechanosensing in liquid-based culture scaffolds.

Adhesion preference of the sticky bacterium Acinetobacter sp. Tol 5

Gram-negative bacterium Acinetobacter sp. Tol 5 exhibits high adhesiveness to various surfaces of general materials, from hydrophobic plastics to hydrophilic glass and metals, via AtaA, an Acinetobacter trimeric autotransporter adhesin Although the adhesion of Tol 5 is nonspecific, Tol 5 cells may have prefer materials for adhesion. Here, we examined the adhesion of Tol 5 and other bacteria expressing different TAAs to various materials, including antiadhesive surfaces. The results highlighted the stickiness of Tol 5 through the action of AtaA, which enabled Tol 5 cells to adhere even to antiadhesive materials, including polytetrafluoroethylene with a low surface free energy, a hydrophilic polymer brush with steric hindrance, and mica with an ultrasmooth surface. Single-cell force spectroscopy as an atomic force microscopy technique revealed the strong cell adhesion force of Tol 5 to these antiadhesive materials. Nevertheless, Tol 5 cells showed a weak adhesion force toward a zwitterionic 2-methacryloyloxyethyl-phosphorylcholine (MPC) polymer-coated surface. Dynamic flow chamber experiments revealed that Tol 5 cells, once attached to the MPC polymer-coated surface, were exfoliated by weak shear stress. The underlying adhesive mechanism was presumed to involve exchangeable, weakly bound water molecules. Our results will contribute to the understanding and control of cell adhesion of Tol 5 for immobilized bioprocess applications and other TAA-expressing pathogenic bacteria of medical importance.

Preliminary Investigation on Efficacy and Safety of Substance P-Coated Stent for Promoting Re-Endothelialization: A Porcine Coronary Artery Restenosis Model

BACKGROUND

Current polymer-based drug-eluting stents (DESs) have fundamental issues about inflammation and delayed re-endothelializaton of the vessel wall. Substance-P (SP), which plays an important role in inflammation and endothelial cells, has not yet been applied to coronary stents. Therefore, this study compares poly lactic-co-glycolic acid (PLGA)-based everolimus-eluting stents (PLGA-EESs) versus 2-methacryloyloxyethyl phosphorylcholine (MPC)-based SP-eluting stents (MPC-SPs) in in-vitro and in-vivo models.

METHODS

The morphology of the stent surface and peptide/drug release kinetics from stents were evaluated. The in-vitro proliferative effect of SP released from MPC-SP is evaluated using human umbilical vein endothelial cell. Finally, the safety and efficacy of the stent are evaluated after inserting it into a pig's coronary artery.

RESULTS

Similar to PLGA-EES, MPC-SP had a uniform surface morphology with very thin coating layer thickness (2.074 μm). MPC-SP showed sustained drug release of SP for over 2 weeks. Endothelial cell proliferation was significantly increased in groups treated with SP (n = 3) compared with the control (n = 3) and those with everolimus (n = 3) (SP: 118.9 ± 7.61% vs. everolimus: 64.3 ± 12.37% vs. the control: 100 ± 6.64%, p < 0.05). In the animal study, the percent stenosis was higher in MPC-SP group (n = 7) compared to PLGA-EES group (n = 7) (MPC-SP: 28.6 ± 10.7% vs. PLGA-EES: 16.7 ± 6.3%, p < 0.05). MPC-SP group showed, however, lower inflammation (MPC-SP: 0.3 ± 0.26 vs. PLGA-EES: 1.2 ± 0.48, p < 0.05) and fibrin deposition (MPC-SP: 1.0 ± 0.73 vs. PLGA-EES: 1.5 ± 0.59, p < 0.05) around the stent strut. MPC-SP showed more increased expression of cluster of differentiation 31, suggesting enhanced re-endothelialization.

CONCLUSION

Compared to PLGA-EES, MPC-SP demonstrated more decreased inflammation of the vascular wall and enhanced re-endothelialization and stent coverage. Hence, MPC-SP has the potential therapeutic benefits for the treatment of coronary artery disease by solving limitations of currently available DESs.

Formation of Polyion Complex Aggregate Formed from a Cationic Block Copolymer and Anionic Polysaccharide

Block copolymers (PmMn; P20M101 and P100M98) comprising poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC, P) containing biocompatible phosphorylcholin pendants and cationic poly((3-acryloylaminopropyl) trimethylammonium chloride) (PMAPTAC, M) were synthesized via a controlled radical polymerization method. The degrees of polymerization of the PMPC and PMAPTAC segments are denoted by subscripts (PmMn). The mixture of cationic PmMn and anionic sodium chondroitin sulfate C (CS) with the pendant anionic carboxylate and sulfonate groups formed polyion complex (PIC) aggregates in phosphate-buffered saline. A charge-neutralized mixture of P20M101 with CS formed P20M101/CS PIC vesicles with a hydrodynamic radius (Rh) of 97.2 nm, zeta potential of ca. 0 mV, and aggregation number (Nagg) of 23,044. PMPC shells covered the surface of the PIC vesicles. The mixture of P100M98 and CS formed PIC spherical micelles with the PIC core and hydrophilic PMPC shells. The Rh, zeta potential, and Nagg of the PIC micelles were 26.4 nm, ca. 0 mV, and 404, respectively. At pH < 4, the carboxylate anions in CS were protonated. Thus, the charge balance in the PIC micelles shifted to decrease the core density owing to the electrostatic repulsions of the excess cations in the core. The PIC micelles dissociated at a NaCl concentration ≥0.6 M owing to the charge screening effect. The positively charged PIC micelles with excess P100M98 can encapsulate anionic dyes owing to electrostatic interaction.

Photoassisted Surface Modification with Zwitterionic Phosphorylcholine Polymers for the Fabrication of Ideal Biointerfaces

Surface modification using zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers is commonly performed to fabricate interfaces that reduce nonspecific fouling by biomolecules and cells. Accordingly, several clinically used devices, such as guide wires, stents, oxygenators, left ventricular assist devices, and microcatheters have been modified using MPC polymers. The specific types of surface modifications vary across substrates and applications. Recently, photoreactions have garnered attention for surface modification due to their stability and tunability. This review highlights various studies that employed photoreactions to modify surfaces using MPC polymers, especially photoinduced graft polymerization of MPC. In addition to antifouling materials, several micromanipulated, long-lasting hydrophilic, and super antiwear surfaces are summarized. Furthermore, several photoreactive MPC polymers that can be used to control interactions between biomolecules and materials are presented along with their potential to form selective recognition surfaces that target biomolecules for biosensors and diagnostic devices.

Zwitterionic polymer on silicone implants inhibits the bacteria-driven pathogenic mechanism and progress of breast implant-associated anaplastic large cell lymphoma

Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) occurs in the capsule surrounding breast implants. Malignant transformation of T cells by bacteria-driven chronic inflammation may be underlying BIA-ALCL mechanism. Here, we covalently grafted 2-methacryloyloxyethyl phosphorylcholine (MPC)-based polymers on a silicone surface and examined its effects against BIA-ALCL pathogenesis. MPC grafting strongly inhibited the adhesion of bacteria and bacteria-causing inflammation. Additionally, cancer T cell proliferation and capsule-derived fibroblast-cancer cell communication were effectively inhibited by MPC grafting. We further demonstrated the effect of MPC against the immune responses causing BIA-ALCL around human silicone implants in micro-pigs. Finally, we generated a xenograft anaplastic T cell lymphoma mouse model around the silicone implants and demonstrated that MPC grafting could effectively inhibit the lymphoma progression. This study is the first to show that bacteria-driven induction and progression of BIA-ALCL can be effectively inhibited by surface modification of implants. STATEMENT OF SIGNIFICANCE: Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is a major concern in the field of plastic and reconstructive surgery. In this study, we demonstrate strong inhibitory effect of zwitterionic polymer grafting on BIA-ALCL pathogenesis and progression, induced by bacterial infection and inflammation, both in vitro and in vivo. This study provides a molecular basis for the development of novel breast implants that can prevent various potential complications such as excessive capsular contracture, breast implant illness, and BIA-ALCL incidence, as well as for expanding the biomedical applications of zwitterionic polymers.

Antifouling polymers for nanomedicine and surfaces: recent advances

Antifouling polymers are materials that can resist nonspecific interactions with cells, proteins, and other biomolecules. Typically, they are hydrophilic polymers with polar or charged moieties that are capable of strong nonbonding interactions with water molecules. This propensity to bind water generates a surface hydration layer that reduces nonspecific interactions with other molecules and is paramount to the antifouling behavior. This property is especially useful for nanoscale applications such as nanomedicine and surface modifications at the molecular level. In nanomedicine, antifouling polymers such as poly(ethylene glycol) and its alternatives play a key role in shielding drug molecules and therapeutic proteins/genes from the immune system within nanoassemblies, thereby enabling effective delivery to target tissues. For coatings, antifouling polymers help to prevent adhesion of cells and molecules to surfaces and are thus valued in marine and biomedical device applications. In this Review, we survey recent advances in antifouling polymers in the context of nanomedicine and coatings, while shining the spotlight on the major polymer classes such as PEG, polyzwitterions, poly(oxazoline)s, and other nonionic hydrophilic polymers.

A Study of the Phosphorylcholine Polymer Coating of a Polymethylpentene Hollow Fiber Membrane

A phosphorylcholine polymer (poly(MPC-co-BMA-co-TSMA), PMBT) was prepared by free radical polymerization and coated on the surface of the polymethylpentene hollow fiber membrane (PMP-HFM). ATR-FTIR and SEM analyses showed that the PMBT polymer containing phosphorylcholine groups was uniformly coated on the surface of the PMP-HFM. Thermogravimetric analysis showed that the PMBT had the best stability when the molar percentage of MPC monomer in the polymer was 35%. The swelling test and static contact angle test indicated that the coating had excellent hydrophilic properties. The fluorescence test results showed that the coating could resist dissolution with 90% (v/v%) ethanol solution and 1% (w/v%) SDS solution. The PMBT coating was shown to be able to decrease platelet adherence to the surface of the hollow fiber membrane, and lower the risk of blood clotting; it had good blood compatibility in tests of whole blood contact and platelet adhesion. These results show that the PMBT polymer may be coated on the surface of the PMP-HFM, and is helpful for improving the blood compatibility of membrane oxygenation.

Current and Future Engineering Strategies for ECMO Therapy

Extracorporeal membrane oxygenation (ECMO) is a last resort therapy for patients with respiratory failure where the gas exchange capacity of the lung is compromised. Venous blood is pumped through an oxygenation unit outside of the body where oxygen diffusion into the blood takes place in parallel to carbon dioxide removal. ECMO is an expensive therapy which requires special expertise to perform. Since its inception, ECMO technologies have been evolving to improve its success and minimize the complications associated with it. These approaches aim for a more compatible circuit design capable of maximum gas exchange with minimal need for anticoagulants. This chapter summarizes the basic principles of ECMO therapy with the latest advancements and experimental strategies aiming for more efficient future designs.

Tethering zwitterionic polymer coatings to mediated glucose biosensor enzyme electrodes can decrease sensor foreign body response yet retain sensor sensitivity to glucose

Foreign body response (FBR) is a major challenge that affects implantable biosensors and medical devices, including glucose biosensors, leading to a deterioration in device response over time. Polymer shields are often used to mitigate this issue. Zwitterionic polymers (ZPs) are a promising class of materials that reduce biofouling of implanted devices. A series of ZPs each containing tetherable epoxide functional groups was synthesised for application as a polymer shield for eventual application as implantable glucose biosensors. The polymer shields were initially tested for the ability to resist fibrinogen adsorption and fibroblast adhesion. All synthesised ZPs showed comparable behaviour to a commercial Lipidure ZP in resisting fibrinogen adsorption. Nafion, a common anionic shield used against electrochemical interferents, showed higher protein adsorption and comparable cell adhesion resistance as uncoated control surfaces. However, a poly(2-methacryloyloxyethyl phosphorylcholine-co-glycidyl methacrylate) (MPC)-type ZP showed similar behaviour to Lipidure, with approximately 50% reduced fibrinogen adsorption and 80% decrease in fibroblast adhesion compared to uncoated controls. An MPC-coated amperometric glucose biosensor showed comparable current density and a 1.5-fold increase in sensitivity over an uncoated control biosensor, whereas all other polymer shields tested, including Lipidure, Nafion and a poly(ethyleneglycol) polymer, resulted in lower sensitivity and current density. Collectively, these characteristics make MPC-polymer shield coatings an appealing possibility for use in implantable glucose sensors and other implanted devices with the aim of reducing FBR while maintaining sensor performance.

Mitigation of Cellular and Bacterial Adhesion on Laser Modified Poly (2-Methacryloyloxyethyl Phosphorylcholine)/Polydimethylsiloxane Surface

Nowadays, using polymers with specific characteristics to coat the surface of a device to prevent undesired biological responses can represent an optimal strategy for developing new and more efficient implants for biomedical applications. Among them, zwitterionic phosphorylcholine-based polymers are of interest due to their properties to resist cell and bacterial adhesion. In this work, the Matrix-Assisted Laser Evaporation (MAPLE) technique was investigated as a new approach for functionalising Polydimethylsiloxane (PDMS) surfaces with zwitterionic poly(2-Methacryloyloxyethyl-Phosphorylcholine) (pMPC) polymer. Evaluation of the physical-chemical properties of the new coatings revealed that the technique proposed has the advantage of achieving uniform and homogeneous stable moderate hydrophilic pMPC thin layers onto hydrophobic PDMS without any pre-treatment, therefore avoiding the major disadvantage of hydrophobicity recovery. The capacity of modified PDMS surfaces to reduce bacterial adhesion and biofilm formation was tested for Gram-positive bacteria, Staphylococcus aureus (S. aureus), and Gram-negative bacteria, Escherichia coli (E. coli). Cell adhesion, proliferation and morphology of human THP-1 differentiated macrophages and human normal CCD-1070Sk fibroblasts on the different surfaces were also assessed. Biological in vitro investigation revealed a significantly reduced adherence on PDMS-pMPC of both E. coli (from 29 × 10 ⁶ to 3 × 10² CFU/mL) and S. aureus (from 29 × 10⁶ to 3 × 10² CFU/mL) bacterial strains. Additionally, coated surfaces induced a significant inhibition of biofilm formation, an effect observed mainly for E. coli. Moreover, the pMPC coatings improved the capacity of PDMS to reduce the adhesion and proliferation of human macrophages by 50% and of human fibroblast by 40% compared to unmodified scaffold, circumventing undesired cell responses such as inflammation and fibrosis. All these highlighted the potential for the new PDMS-pMPC interfaces obtained by MAPLE to be used in the biomedical field to design new PDMS-based implants exhibiting long-term hydrophilic profile stability and better mitigating foreign body response and microbial infection.

Zwitterionic Biomaterials

The term "zwitterionic polymers" refers to polymers that bear a pair of oppositely charged groups in their repeating units. When these oppositely charged groups are equally distributed at the molecular level, the molecules exhibit an overall neutral charge with a strong hydration effect via ionic solvation. The strong hydration effect constitutes the foundation of a series of exceptional properties of zwitterionic materials, including resistance to protein adsorption, lubrication at interfaces, promotion of protein stabilities, antifreezing in solutions, etc. As a result, zwitterionic materials have drawn great attention in biomedical and engineering applications in recent years. In this review, we give a comprehensive and panoramic overview of zwitterionic materials, covering the fundamentals of hydration and nonfouling behaviors, different types of zwitterionic surfaces and polymers, and their biomedical applications.

Surface characterization of an ultra-soft contact lens material using an atomic force microscopy nanoindentation method

As new ultra-soft materials are being developed for medical devices and biomedical applications, the comprehensive characterization of their physical and mechanical properties is both critical and challenging. To characterize the very low surface modulus of the novel biomimetic lehfilcon A silicone hydrogel contact lens coated with a layer of a branched polymer brush structure, an improved atomic force microscopy (AFM) nanoindentation method has been applied. This technique allows for precise contact-point determination without the effects of viscous squeeze-out upon approaching the branched polymer. Additionally, it allows individual brush elements to be mechanically characterized in the absence of poroelastic effects. This was accomplished by selecting an AFM probe with a design (tip size, geometry, and spring constant) that was especially suited to measuring the properties of soft materials and biological samples. The enhanced sensitivity and accuracy of this method allows for the precise measurement of the very soft lehfilcon A material, which has an extremely low elastic modulus in the surface region (as low as 2 kPa) and extremely high elasticity (nearly 100%) in an aqueous environment. The surface-characterization results not only reveal the ultra-soft nature of the lehfilcon A lens surface but also demonstrate that the elastic modulus exhibits a 30 kPa/200 nm gradient with depth due to the disparity between the modulus of the branched polymer brushes and the SiHy substrate. This surface-characterization methodology may be applied to other ultra-soft materials and medical devices.

Effect of Poly(Oxanorbonene)- and Poly(Methacrylate)-Based Polyzwitterionic Surface Coatings on Cell Adhesion and Gene Expression of Human Keratinocytes

Polyzwitterions are generally known for their anti-adhesive properties, including resistance to protein and cell adhesion, and overall high bio-inertness. Yet there are a few polyzwitterions to which mammalian cells do adhere. To understand the structural features of this behavior, a panel of polyzwitterions with different functional groups and overall degrees of hydrophobicity is analyzed here, and their physical and biological properties are correlated to these structural differences. Cell adhesion is focused on, which is the basic requirement for cell viability, proliferation, and growth. With the here presented polyzwitterion panel, three different types of cell-surface interactions are observed: adhesion, slight attachment, and cell repellency. Using immunofluorescence methods, it is found that human keratinocytes (HaCaT) form focal adhesions on the cell-adhesive polyzwitterions, but not on the sample that has only slight cell attachment. Gene expression analysis indicates that HaCaT cells cultivated in the presence of a non-adhesive polyzwitterion have up-regulated inflammatory and apoptosis-related cell signaling pathways, while the gene expression of HaCaT cells grown on a cell-adhesive polyzwitterion does not differ from the gene expression of the growth control, and thus can be defined as fully cell-compatible.

Improvement of Oral Absorption of Poorly Water-Soluble Drugs by Solid Dispersions with Amphiphilic Phospholipid Polymer

Solid dispersions are one of methods for solubilizing water-insoluble drugs. To enhance the bioavailability, maintenance of the supersaturated state and absorption of the dissolved drug in the gastrointestinal tract are important. We designed and synthesized amphiphilic 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymers as carriers for solid dispersions and evaluated the dissolution behavior in test solutions with different pH and additives. Solid dispersion of troglitazone with amphiphilic MPC copolymers having both aromatic rings and urethane bonds in the side chains showed rapid dissolution and excellent supersaturation maintenance. It was indicated that the balance between the interactions with drug molecules and the water affinity of the polymer should be considered when carriers for solid dispersions are designed. In addition, cell membrane permeability of the solid dispersion with the amphiphilic MPC copolymer was evaluated by the Dissolution / Permeation system, which consists of two liquid chambers and a monolayer of epithelial cells that mimics the intestinal dissolution and permeation process. Further, blood concentration of the drug when solid dispersions were orally administered in mice was also evaluated. The cell membrane permeability and oral absorbability were significantly improved, compared to the solid dispersions with poly(N-vinylpyrrolidone) and suspension or solution of crystalline troglitazone.

Novel protein-repellent and antibacterial polymethyl methacrylate dental resin in water-aging for 6 months

Background

The present study aimed to develop a novel protein-repellent and antibacterial polymethyl methacrylate (PMMA) dental resin with 2-methacryloyloxyethyl phosphorylcholine (MPC) and quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM), and to investigate the effects of water-aging for 6 months on the mechanical properties, protein adsorption, and antibacterial activity of the dental resin.

Methods

Four groups were tested: PMMA control; PMMA + 3% MPC; PMMA + 1.5% DMAHDM; and PMMA + 3% MPC + 1.5% DMADDM in acrylic resin powder. Specimens were water-aged for 1 d, 3 months, and 6 months at 37 ℃. Their mechanical properties were then measured using a three-point flexure test. Protein adsorption was measured using a micro bicinchoninic acid (BCA) method. A human saliva microcosm model was used to inoculate bacteria on water-aged specimens and to investigate the live/dead staining, metabolic activity of biofilms, and colony-forming units (CFUs).

Results

The flexural strength and elastic modulus showed a significant loss after 6 months of water-ageing for the PMMA control (mean ± SD; n = 10); in contrast, the new protein repellent and antibacterial PMMA resin showed no strength loss. The PMMA–MPC–DMAHDM-containing resin imparted a strong antibacterial effect by greatly reducing biofilm viability and metabolic activity. The biofilm CFU count was reduced by about two orders of magnitude (p < 0.05) compared with that of the PMMA resin control. The protein adsorption was 20% that of a commercial composite (p < 0.05). Furthermore, the PMMA–MPC–DMAHDM-containing resin exhibited a long-term antibacterial performance, with no significant difference between 1 d, 3 months and 6 months (p > 0.05).

Conclusions

The flexural strength and elastic modulus of the PMMA–MPC–DMAHDM-containing resin were superior to those of the PMMA control after 6 months of water-ageing. The novel PMMA resin incorporating MPC and DMAHDM exhibited potent and lasting protein-repellent and antibacterial properties.

Biomimetic materials based on zwitterionic polymers toward human-friendly medical devices

This review summarizes recent research on the design of polymer material systems based on biomimetic concepts and reports on the medical devices that implement these systems. Biomolecules such as proteins, nucleic acids, and phospholipids, present in living organisms, play important roles in biological activities. These molecules are characterized by heterogenic nature with hydrophilicity and hydrophobicity, and a balance of positive and negative charges, which provide unique reaction fields, interfaces, and functionality. Incorporating these molecules into artificial systems is expected to advance material science considerably. This approach to material design is exceptionally practical for medical devices that are in contact with living organisms. Here, it is focused on zwitterionic polymers with intramolecularly balanced charges and introduce examples of their applications in medical devices. Their unique properties make these polymers potential surface modification materials to enhance the performance and safety of conventional medical devices. This review discusses these devices; moreover, new surface technologies have been summarized for developing human-friendly medical devices using zwitterionic polymers in the cardiovascular, cerebrovascular, orthopedic, and ophthalmology fields.

The Influence of 2-Methacryloyloxyethyl Phosphorylcholine Polymer Materials on Orthodontic Friction and Attachment of Oral Bacteria

There is no clinical evidence of the usage of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers in dental practice. We performed in vitro studies to determine whether the application of an MPC coating to stainless steel orthodontic wires confers low-friction and antimicrobial properties to these wires. The friction test on MPC-coated wires was performed using a precision universal/tensile tester. MPC polymer was coated on a 50 × 50 mm stainless steel plate, and samples were assessed using an antimicrobial activity test. To verify the effect of MPC polymer-treated wires on experimental tooth movement models in vitro, examinations were performed on typodonts to determine the improvement in tooth movement efficiency. The polymer treatment wire groups demonstrated significantly enhanced tooth movement compared with the untreated wire groups, at both 50 g and 100 g traction forces. The results indicated that MPC coating inhibited the attachment of oral bacteria, such as Streptococcus mutans, on a stainless steel plate. Additionally, the coating seemed to improve the efficiency of tooth movement by reducing the occurrence of friction. The application of an MPC coating onto stainless steel wires, which are used as orthodontic materials, may reduce static friction and bacterial adherence to the oral cavity and improve tooth movement.

Safety and Efficacy of a New Water Gradient Biomimetic Monthly Replacement Spherical Contact Lens Material (Lehfilcon A)

Purpose

The objective of this study was to evaluate the safety and performance of the investigational lens, lehfilcon A, when worn in a daily wear modality and replaced monthly as compared to the commercially available comfilcon A contact lens.

Methods

This was a multicenter, prospective, controlled, double-masked, randomized, parallel-group clinical study with bilateral lens wear for 3 months. In all, 115 subjects completed the study (77 with test lehfilcon A and 38 with control comfilcon A contact lenses). Distance visual acuity (VA) was assessed using Snellen VA. Lens performance was assessed by examining lens fit/movement, centration, front surface wettability and front/back surface deposits using slit-lamp biomicroscopy.

Results

At the 3-month follow-up visit, all eyes had a distance VA of 20/20 or better. Further, lens fit/movement was assessed as optimal in 92.9% of the eyes with lehfilcon A and 89.2% with comfilcon A. There were no ratings of unacceptably tight or loose fits for either contact lens material. Lens centration was assessed as optimal in 98.7% of eyes with lehfilcon A and 94.6% with comfilcon A. For front and back surface deposits, both materials showed minimal lens surface deposits. Front surface wettability was assessed as grade 0 or 1 for most of the study lenses in both lens groups across all attended study visits. There were no ocular adverse events related to the study lenses.

Conclusion

Overall, lehfilcon A showed excellent VA, optimal lens fitting characteristics, a clean surface, high wettability, and low risk for adverse events after 3 months of lens wear.

Roles of interfacial water states on advanced biomedical material design

When biomedical materials come into contact with body fluids, the first reaction that occurs on the material surface is hydration; proteins are then adsorbed and denatured on the hydrated material surface. The amount and degree of denaturation of adsorbed proteins affect subsequent cell behavior, including cell adhesion, migration, proliferation, and differentiation. Biomolecules are important for understanding the interactions and biological reactions of biomedical materials to elucidate the role of hydration in biomedical materials and their interaction partners. Analysis of the water states of hydrated materials is complicated and remains controversial; however, knowledge about interfacial water is useful for the design and development of advanced biomaterials. Herein, we summarize recent findings on the hydration of synthetic polymers, supramolecular materials, inorganic materials, proteins, and lipid membranes. Furthermore, we present recent advances in our understanding of the classification of interfacial water and advanced polymer biomaterials, based on the intermediate water concept.

Polycarboxybetaine-Based Hydrogels for the Capture and Release of Circulating Tumor Cells

Circulating tumor cells (CTCs) are indicators for the detection, diagnosis, and monitoring of cancers and offer biological information for the development of personalized medicine. Techniques for the specific capture and non-destructive release of CTCs from millions of blood cells remain highly desirable. Here, we present a CTC capture-and-release system using a disulfide-containing poly(carboxybetaine methacrylate) (pCB) hydrogel. The non-fouling characteristic of pCB prevents unwanted, nonspecific cell binding, while the carboxyl functionality of pCB is used for the conjugation of anti-epithelial cell adhesion molecule (anti-EpCAM) antibodies for the capture of CTCs. The results demonstrated that the anti-EpCAM-conjugated pCB hydrogel captured HCT116 cells from blood, and the capture ratio reached 45%. Furthermore, the captured HCT116 cells were released within 30 min from the dissolution of the pCB hydrogel by adding cysteine, which breaks the disulfide bonds of the crosslinkers. The cells released were viable and able to grow. Our system has potential in the development of a device for CTC diagnosis.

Cell-membrane-inspired polymers for constructing biointerfaces with efficient molecular recognition

Fabrication of devices that accurately recognize, detect, and separate target molecules from mixtures is a crucial aspect of biotechnology for applications in medical, pharmaceutical, and food sciences. This technology has also been recently applied in solving environmental and energy-related problems. In molecular recognition, biomolecules are typically complexed with a substrate, and specific molecules from a mixture are recognized, captured, and reacted. To increase sensitivity and efficiency, the activity of the biomolecules used for capture should be maintained, and non-specific reactions on the surface should be prevented. This review summarizes polymeric materials that are used for constructing biointerfaces. Precise molecular recognition occurring at the surface of cell membranes is fundamental to sustaining life; therefore, materials that mimic the structure and properties of this particular surface are emphasized in this article. The requirements for biointerfaces to eliminate nonspecific interactions of biomolecules are described. In particular, the major issue of protein adsorption on biointerfaces is discussed by focusing on the structure of water near the interface from a thermodynamic viewpoint; moreover, the structure of polymer molecules that control the water structure is considered. Methodologies enabling stable formation of these interfaces on material surfaces are also presented.

Preparation of Biocompatible Poly(2-(methacryloyloxy)ethyl phosphorylcholine) Hollow Particles Using Silica Particles as a Template

Hydrophilic poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) shows biocompatibility because the pendant phosphorylcholine group has the same chemical structure as the hydrophilic part of phospholipids that form cell membranes. Hollow particles can be used in various fields, such as a carrier in drug delivery systems because they can encapsulate hydrophilic drugs. In this study, vinyl group-decorated silica particles with a radius of 150 nm were covered with cross-linked PMPC based on the graft-through method. The radius of PMPC-coated silica particles increased compared to that of the original silica particles. The PMPC-coated silica particles were immersed in a hydrogen fluoride aqueous solution to remove template silica particles to prepare the hollow particles. The PMPC hollow particles were characterized by dynamic light scattering, infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy observations. The thickness of the hollow particle shell can be controlled by the polymerization solvent quality. When a poor solvent for PMPC was used for the polymerization, PMPC hollow particles with thick shells can be obtained. The PMPC hollow particles can encapsulate hydrophilic guest molecules by immersing the hollow particles in a high-concentration guest molecule solution. The biocompatible PMPC hollow particles can be used in a drug carrier.

Formation of Water-Soluble Complexes from Fullerene with Biocompatible Block Copolymers Bearing Pendant Glucose and Phosphorylcholine

Double-hydrophilic diblock copolymers, PMPC₁₀₀-block-PGEMA_n (M₁₀₀G_n), were synthesized via reversible addition-fragmentation chain transfer radical polymerization using glycosyloxyethyl methacrylate and 2-(methacryloyloxy)ethyl phosphorylcholine. The degree of polymerization (DP) of the poly(2-(methacryloyloxy) ethylphosphorylcholine) (PMPC) block was 100, whereas the DPs (n) of the poly(glycosyloxyethyl methacrylate) PGEMA block were 18, 48, and 90. Water-soluble complexes of C₇₀/M₁₀₀G_n and fullerene (C₇₀) were prepared by grinding M₁₀₀G_n and C₇₀ powders in a mortar and adding phosphate-buffered saline (PBS) solution. PMPC can form a water-soluble complex with hydrophobic C₇₀ using the same method. Therefore, the C₇₀/M₁₀₀G_n complexes have a core-shell micelle-like particle structure possessing a C₇₀/PMPC core and PGEMA shells. The maximum amounts of solubilization of C₇₀ in PBS solutions using 2 g/L each of M₁₀₀G₁₈, M₁₀₀G₄₈, and M₁₀₀G₉₀ were 0.518, 0.358, and 0.257 g/L, respectively. The hydrodynamic radius (R_h) of C₇₀/M₁₀₀G_n in PBS solutions was 55-75 nm. Spherical aggregates with a similar size to the R_h were observed by transmission electron microscopy. When the C₇₀/M₁₀₀G_n PBS solutions were irradiated with visible light, singlet oxygen was generated from C₇₀ in the core. It is expected that the C₇₀/M₁₀₀G_n complexes can be applied to photosensitizers for photodynamic therapy treatments.

pH-Responsive Association Behavior of Biocompatible Random Copolymers Containing Pendent Phosphorylcholine and Fatty Acid

Well-defined pH-responsive biocompatible random copolymers composed of 2-(methacryloyloxy)ethyl phosphorylcholine and varying quantities of sodium 11-(acrylamido)undecanoate (AaU) (f_AaU = 0-58 mol %) were synthesized via reversible addition-fragmentation chain transfer radical polymerization. The pH-responsive association and dissociation behavior of the random copolymers was studied via turbidity, ¹H nuclear magnetic resonance relaxation time, dynamic light scattering, static light scattering (SLS), and fluorescence measurements. At basic pH levels, the random copolymers dissolved in water in a unimer state because the AaU units behaved in a hydrophilic manner as a result of the ionization of the pendent fatty acids. The random copolymers with f_AaU < 52 mol % associated intramolecularly within a single polymer chain to form unimer micelles at pH 3 because of the protonation of the pendent fatty acids. On the other hand, the random copolymer with f_AaU ≥ 52 mol % formed intermolecular aggregates composed of four polymer chains at pH 3, as established by the SLS measurements. The random copolymers displayed the ability to solubilize hydrophobic guest molecules, such as N-phenyl-1-naphthylamine, into the hydrophobic microdomain formed by the pendent dehydrated fatty acids at acidic pHs. At pH 4, 1-pyrememethanol is captured by the random copolymer with f_AaU = 52 mol %, and it is released from the random copolymer above pH 9. Furthermore, the mucoadhesive properties of the random copolymer with f_AaU = 9 mol % were studied using a surface plasmon resonance technique. The copolymer was adsorbed onto mucin at pH 3; however, the adsorption decreased at pH 7.4.

Photoresponsive behaviour of zwitterionic polymer particles with photodimerizable groups on their surfaces

Polymer particles with precise diameters have been used as building blocks for fabricating well-defined and nanostructured materials. Polymer particles as building blocks for medical applications require both easily spatiotemporal manipulation and good biocompatibility. In this study, we designed zwitterionic polymer particles with photodimerizable groups on their surfaces and used ultraviolet (UV) light irradiation to photo-assemble them in aqueous media. After synthesizing zwitterionic polymer particles with diameters ranging from 100-200 nm via soap-free emulsion polymerization, maleimide moieties as photodimerizable groups were introduced onto the particle surfaces. UV light irradiation to an aqueous dispersion of zwitterionic polymer particles with photodimerizable groups induced their photo-assembling because interparticle bonding forms by photodimerization of the photodimerizable groups on the particle surfaces. The zwitterionic surface of their particle-assembled films effectively suppressed protein adsorption, cell adhesion, and platelet adhesion. The photoresponsive behaviour and bioinert surface of the zwitterionic polymer particles with photodimerizable groups indicate that they have several potential applications as bioinert building blocks for designing well-defined and nanostructured biomaterials used in biosensors, bioseparation and cell culture, and for modifying and repairing biomaterial surfaces in situ.

A biomimetic anti-biofouling coating in nanofluidic channels

A biomimetic coating using a tailored phosphorylcholine-containing monomer enables to suppress non-specific protein adsorption in nanofluidic channels, paving a way to explore a new anti-biofouling strategy using monomer-based materials for nanodevices.

Emerging Phospholipid Nanobiomaterials for Biomedical Applications to Lab-on-a-Chip, Drug Delivery, and Cellular Engineering

The design of advanced nanobiomaterials to improve analytical accuracy and therapeutic efficacy has become an important prerequisite for the development of innovative nanomedicines. Recently, phospholipid nanobiomaterials including 2-methacryloyloxyethyl phosphorylcholine (MPC) have attracted great attention with remarkable characteristics such as resistance to nonspecific protein adsorption and cell adhesion for various biomedical applications. Despite many recent reports, there is a lack of comprehensive review on the phospholipid nanobiomaterials from synthesis to diagnostic and therapeutic applications. Here, we review the synthesis and characterization of phospholipid nanobiomaterials focusing on MPC polymers and highlight their attractive potentials for applications in micro/nanofabricated fluidic devices, biosensors, lab-on-a-chip, drug delivery systems (DDSs), COVID-19 potential usages for early diagnosis and even treatment, and artificial extracellular matrix scaffolds for cellular engineering.

Preparation of a thermo-responsive drug carrier consisting of a biocompatible triblock copolymer and fullerene

A triblock copolymer (PEG-b-PUEM-b-PMPC; EUM) comprising poly(ethylene glycol) (PEG), thermo-responsive poly(2-ureidoethyl methacrylate) (PUEM), and poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) blocks was synthesized via controlled radical polymerization. PEG and PMPC blocks exhibit hydrophilicity and biocompatibility. The PUEM block exhibits an upper critical solution temperature (UCST). PMPC can dissolve hydrophobic fullerenes in water to form a complex by grinding PMPC and fullerene powders. Fullerene-C₇₀ (C₇₀) and EUM were ground in a mortar and phosphate-buffered saline (PBS) was added to synthesize a water-soluble complex (C₇₀/EUM). C₇₀/EUM has a core-shell-corona structure, whose core is a complex of C₇₀ and PMPC, the shell is PUEM, and corona is PEG. The maximum C₇₀ concentration dissolved in PBS was 0.313 g L^-1 at an EUM concentration of 2 g L^-1. The C₇₀/EUM hydrodynamic radius (R_h) was 34 nm in PBS at 10 °C, which increased due to the PUEM block's UCST phase transition with increasing temperature, and R_h attained a constant value of 38 nm above 36 °C. An anticancer drug, doxorubicin, was encapsulated in the PUEM shell by hydrophobic interactions in C₇₀/EUM at room temperature, which can be released by heating. The generation of singlet oxygen (¹O₂) from C₇₀/EUM upon visible-light irradiation was confirmed using the singlet oxygen sensor green indicator. Water-soluble C₇₀/EUM may be used as a carrier that releases encapsulated drugs when heated and as a photosensitizer for photodynamic therapy.

Cardiomyogenic Differentiation Potential of Human Dilated Myocardium-Derived Mesenchymal Stem/Stromal Cells: The Impact of HDAC Inhibitor SAHA and Biomimetic Matrices

Dilated cardiomyopathy (DCM) is the most common type of nonischemic cardiomyopathy characterized by left ventricular or biventricular dilation and impaired contraction leading to heart failure and even patients’ death. Therefore, it is important to search for new cardiac tissue regenerating tools. Human mesenchymal stem/stromal cells (hmMSCs) were isolated from post-surgery healthy and DCM myocardial biopsies and their differentiation to the cardiomyogenic direction has been investigated in vitro. Dilated hmMSCs were slightly bigger in size, grew slower, but had almost the same levels of MSC-typical surface markers as healthy hmMSCs. Histone deacetylase (HDAC) activity in dilated hmMSCs was 1.5-fold higher than in healthy ones, which was suppressed by class I and II HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) showing activation of cardiomyogenic differentiation-related genes alpha-cardiac actin (ACTC1) and cardiac troponin T (TNNT2). Both types of hmMSCs cultivated on collagen I hydrogels with hyaluronic acid (HA) or 2-methacryloyloxyethyl phosphorylcholine (MPC) and exposed to SAHA significantly downregulated focal adhesion kinase (PTK2) and activated ACTC1 and TNNT2. Longitudinal cultivation of dilated hmMSC also upregulated alpha-cardiac actin. Thus, HDAC inhibitor SAHA, in combination with collagen I-based hydrogels, can tilt the dilated myocardium hmMSC toward cardiomyogenic direction in vitro with further possible therapeutic application in vivo.

Evaluation of the long-term antibiofilm effect of a surface coating with dual functionality of antibacterial and protein-repellent effects

The provision of antibacterial properties to resinous restorative/reconstructive materials by incorporating polymerizable bactericides such as 12-methacryloyloxydodecylpyridinium bromide (MDPB) has been attempted. Previously, MDPB was combined with 2-methacryloyloxyethyl phosphorylcholine (MPC) to fabricate a copolymer coating to increase antibacterial effectiveness by protein repelling. In this study, we assessed the longevity of the protein-repelling, antibacterial, and antibiofilm effects of the MDPB-MPC copolymer. After 28 days of water immersion, MPC-containing copolymers exhibited lower adsorption of bovine serum albumin and salivary proteins; after 24 h of incubation, MDPB-containing copolymers demonstrated antibacterial effects against Streptococcus mutans. The copolymer containing both MDPB and MPC showed thinner biofilm formation with a higher percentage of membrane-compromised bacteria than control. The results were consistent with those before aging, indicating the long-lasting antibacterial, protein-repellent, and antibiofilm effects of this copolymer. The durable copolymer developed in this study can be applied to dental resins to control bacteria in the oral environment.

Multifunctional Biomedical Materials Derived from Biological Membranes

The delicate structure and fantastic functions of biological membranes are the successful evolutionary results of a long-term natural selection process. Their excellent biocompatibility and biofunctionality are widely utilized to construct multifunctional biomedical materials mainly by directly camouflaging materials with single or mixed biological membranes, decorating or incorporating materials with membrane-derived vesicles (e.g., exosomes), and designing multifunctional materials with the structure/functions of biological membranes. Here, the structure-function relationship of some important biological membranes and biomimetic membranes are discussed, such as various cell membranes, extracellular vesicles, and membranes from bacteria and organelles. Selected literature examples of multifunctional biomaterials derived from biological membranes for biomedical applications, such as drug- and gene-delivery systems, tissue-repair scaffolds, bioimaging, biosensors, and biological detection, are also highlighted. These designed materials show excellent properties, such as long circulation time, disease-targeted therapy, excellent biocompatibility, and selective recognition. Finally, perspectives and challenges associated with the clinical applications of biological-membrane-derived materials are discussed.

Nanoparticle shell structural cues drive in vitro transport properties, tissue distribution and brain accessibility in zebrafish

Zwitterion polymers with strong antifouling properties have been suggested as the prime alternative to polyethylene glycol (PEG) for drug nanocarriers surface coating. It is believed that PEG coating shortcomings, such as immune responses and incomplete protein repellency, could be overcome by zwitterionic polymers. However, no systematic study has been conducted so far to complete a comparative appraisal of PEG and zwitterionic-coating effects on nanoparticles (NPs) stealthness, cell uptake, cell barrier translocation and biodistribution in the context of nanocarriers brain targeting. Core-shell polymeric particles with identical cores and a shell of either PEG or poly(2-methacryloyloxyethyl phosphorylcholine (PMPC) were prepared by impinging jet mixer nanoprecipitation. NPs with similar size and surface potential were systematically compared using in vitro and in vivo assays. NPs behavior differences were rationalized based on their protein-particles interactions. PMPC-coated NPs were significantly more endocytosed by mouse macrophages or brain resident macrophages compared to PEGylated NPs but exhibited the remarkable ability to cross the blood-brain barrier in in vitro models. Nanoscale flow cytometry assays showed significantly more adsorbed proteins on PMPC-coated NPs than PEG-coated NPs. In vivo, distribution in zebrafish larvae, showed a strong propensity for PMPC-coated NPs to adhere to the vascular endothelium, while PEG-coated NPs were able to circulate for a longer time and escape the bloodstream to penetrate deep into the cerebral tissue. The stark differences between these two types of particles, besides their similarities in size and surface potential, points towards the paramount role of surface chemistry in controlling NPs fate likely via the formation of distinct protein corona for each coating.

Polybetaines in Biomedical Applications

Polybetaines, that have moieties bearing both cationic (quaternary ammonium group) and anionic groups (carboxylate, sulfonate, phosphate/phosphinate/phosphonate groups) situated in the same structural unit represent an important class of smart polymers with unique and specific properties, belonging to the family of zwitterionic materials. According to the anionic groups, polybetaines can be divided into three major classes: poly(carboxybetaines), poly(sulfobetaines) and poly(phosphobetaines). The structural diversity of polybetaines and their special properties such as, antifouling, antimicrobial, strong hydration properties and good biocompatibility lead to their use in nanotechnology, biological and medical fields, water remediation, hydrometallurgy and the oil industry. In this review we aimed to highlight the recent developments achieved in the field of biomedical applications of polybetaines such as: antifouling, antimicrobial and implant coatings, wound healing and drug delivery systems.

Solubilization of Paclitaxel by Self-Assembled Amphiphilic Phospholipid-Mimetic Polymers with Varied Hydrophobicity

2-Methacryloyloxyethyl phosphorylcholine (MPC) polymers have been used as a coating agent on medical devices and as a carrier in drug delivery systems (DDSs). Paclitaxel (PTX) is a water-insoluble anticancer drug whose solubilizer is necessary for administration. Block and random copolymers composed of hydrophilic MPC and butyl methacrylate, named PMB, show different properties, depending on the polymer sequence and MPC content. In the present study, we used amphiphilic MPC polymers comprising hydrophobic dodecyl methacrylate (DMA). The self-assembling properties and PTX solubilization of random and block poly(MPC-co-DMA)s (rPMDs and bPMDs) with different compositions were examined and compared. rPMDs with high DMA content formed large and relatively loose self-assembled structures, which solubilized PTX. However, bPMDs formed small and compact self-assembled structures with poor PTX solubilization. PTX solubilized by PMB with small and loose self-assembled structures showed efficient drug action, similar to free PTX; however, rPMDs fell short of demonstrating PTX efficiency. Our results suggest that the self-assembling properties and the hydrophobicity of amphiphilic MPC polymers largely affect PTX solubilization as well as drug action, which is required to be controlled by the polymer sequence, as well as the structure and composition of the hydrophobic monomer for efficient DDS.

Poly 2-methacryloyloxyethyl Phosphorylcholine Protects Corneal Cells and Contact Lenses from Desiccation Damage

SIGNIFICANCE

Contact lens (CL) wearing may cause discomfort and eye dryness. We describe here the efficacy of a synthetic polymer in protecting both the corneal epithelial cells and the CL from desiccation damage. Artificial tears containing this polymer might be helpful to treat or prevent ocular surface damage in CL wearers.

PURPOSE

We aimed to investigate the protective effects of the synthetic polymer 2-methacryloyloxyethyl phosphorylcholine (poly-MPC) on corneal epithelial cells and CLs subjected to desiccation damage.

METHODS

The interaction of poly-MPC with the cell membrane was evaluated on human primary corneal epithelial cells (HCE-F) by the sodium dodecyl sulfate damage protection assay or the displacement of the cell-binding lectin concanavalin A (ConA). Survival in vitro of HCE-F cells and ex vivo of porcine corneas exposed to desiccating conditions after pre-treatment with poly-MPC or hyaluronic acid (HA), hypromellose (HPMC), and trehalose was evaluated by a colorimetric assay. Soft CLs were soaked overnight in a solution of poly-MPC/HPMC and then let dry in ambient air. Contact lens weight, morphology, and transparency were periodically registered until complete dryness.

RESULTS

Polymer 2-methacryloyloxyethyl phosphorylcholine and HPMC were retained on the HCE-F cell membrane more than trehalose or HA. Polymer 2-methacryloyloxyethyl phosphorylcholine, HA, and HPMC either alone or in association protected corneal cells from desiccation significantly better than did trehalose alone or in association with HA. Contact lens permeation by poly-MPC/HPMC preserved better their shape and transparency than did saline.

CONCLUSIONS

Polymer 2-methacryloyloxyethyl phosphorylcholine coats and protects corneal epithelial cells and CLs from desiccation damage more efficiently compared with trehalose and as good as other reference compounds.

Application of Zwitterionic Polymer Hydrogels to Optical Tissue Clearing for 3D Fluorescence Imaging

Zwitterionic polymers have both anion and cation groups in the side chain and have been used in various biomedical applications because of the unique properties. In this study, zwitterionic polymer hydrogels are applied to optical tissue clearing for 3D fluorescence imaging. Polyacrylamide hydrogels have been employed in Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging/Immunostaining/In situ-hybridization-compatible Tissue-hYdrogel method. Zwitterionic polymer hydrogels are produced using zwitterionic monomers, such as 3-[(3-acrylamidopropyl)dimethylammonio]propane-1-sulfonate (DAPS) and 2-methacryloyloxyethyl phosphorylcholine (MPC), and crosslinkers. The hydrogels made from poly(DAPS-co-acrylamide) and MPC homopolymers afford the most transparent tumor tissues. However, the tissues cleared using DAPS copolymers-containing hydrogels became turbid in a refractive index-matching solution, which are unable to obtain clear 3D fluorescence images. In contrast, the 3D fluorescence imaging is achieved in the MPC polymer-treated 2-mm-thick brain slices after immunostaining. The 3D fluorescence imaging of lung metastasis that is cleared by the MPC hydrogel to demonstrate the possible application to cancer diagnosis is performed. The results indicate the increased potentials of zwitterionic polymer hydrogels, especially MPC polymer hydrogels, in biomedical applications.

Efficacy of hydrated phospholipid polymer interfaces between all-polymer bearings for total hip arthroplasty

Measurements of wear resistance and metal ion release are important for designing bearing couples or interfaces in total hip arthroplasty (THA). In this study, we investigated wear resistance and metal ion release of surface-modified metal-free all-polymer hip bearings, such as poly(ether-ether-ketone), (PEEK) on cross-linked polyethylene (PEEK-on-CLPE), with a hydrated gel-like surface layer, to propose an improved alternative to the conventional materials used to design THA bearings. The PEEK surface resulted in less metal ion release than the cobalt-chromium-molybdenum (Co-Cr-Mo) alloy surface owing to the lack of metal. The PEEK-on-CLPE bearing (6.33 mg/10⁶  cycles) had lower wear (rate) than the bearing with Co-Cr-Mo alloy-on-CLPE (10.47 mg/10⁶  cycles) under controlled laboratory conditions; the wear performance of the all-polymer hip bearings was further improved with hemi- or both-surface modified with a hydrated poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer (3.74 and 3.06 mg/10⁶  cycles, respectively). The PMPC-grafted interface of PEEK-on-CLPE will be especially suitable for THA candidates. This study is of key importance for the design of lifelong THA and a better understanding of the limitations resulting from using PEEK. Further studies are necessary to evaluate the possibility of using this material in artificial hips.