2-Methacryloyloxyethyl phosphorylcholine (MPC)-polymer suppresses an increase of oral bacteria: a single-blind, crossover clinical trial

2-methacryloyloxyethyl phosphorylcholine polymer treatment prevents Candida albicans biofilm formation on acrylic resin

PURPOSE

We aimed to evaluate the effectiveness of photoreactive 2-methacryloyloxyethyl phosphorylcholine (MPC) in inhibiting Candida albicans biofilm formation on polymethyl methacrylate (PMMA) and assess its mechanism and need for re-application by evaluating its interaction with salivary mucin and durability during temperature changes.

METHODS

PMMA discs were used as specimens. The MPC coating was applied using the spray and cure technique for the treatment groups, whereas no coating was applied to the control. The MPC treatment (MT) groups were further differentiated based on the number of thermal cycles involved (0, 1000, 2500, and 5000). The optical density was measured to assess mucin adsorption (MA). Contact angle (CA) was calculated to evaluate surface hydrophilicity. The presence of MPC components on the PMMA surface was assessed using X-ray photoelectron spectroscopy (XPS). C. albicans biofilms were evaluated qualitatively (scanning electron microscope images) and quantitatively (colony-forming units (CFUs)). Statistical analysis was conducted using two-way analysis of variance and Tukey's multiple comparison test.

RESULTS

MA rate and CA increased significantly in the MT groups, which exhibited significantly fewer CFUs and thinner biofilms than those of the control group. Based on the XPS, MA, and CFU evaluations, the durability and efficacy of the MPC coating were considered stable up to 2500 thermal cycles. Additionally, a significant interaction was observed between mucin concentration and MPC efficacy.

CONCLUSIONS

The photoreactive MPC coating, which was resistant to temperature changes for approximately 3 months, effectively prevented C. albicans biofilm formation by modifying surface hydrophilicity and increasing mucin adsorption.

Using Catechol and Zwitterion-Functionalized Copolymers to Prevent Dental Bacterial Adhesion

In this manuscript, we report the synthesis of zwitterionic copolymers and their ability to form antifouling coatings on porous hydroxyapatite as a mimic of dental coatings. Specifically, we systematically investigated how altering the composition of copolymers of catechol methacrylate (Cat-MA or 2) and methacryloyloxyethyl phosphorylcholine (2-MPC) with varying catechol-to-zwitterion ratios impacted their adhesive and antifouling properties, allowing for the rational design of functional coatings. Characterization by ellipsometry, contact angle goniometry, and X-ray photoelectron spectroscopy revealed the presence of hydrophilic copolymer coatings of ∼10 nm thickness. Notably, these copolymers adhered to hydroxyapatite and reduced the level of attachment of both Gram-negative Escherichia coli and Gram-positive Streptococcus oralis. Additionally, in vitro experiments that mimicked the complex mouth environment (i.e., swallowing and using mouthwash) were employed to evaluate S. oralis adhesion, finding that the copolymer coatings reduced the quantity of adhered bacteria. We suggest that these copolymers provide insights into the design of antifouling coatings that are appropriate for use in oral care.

The biosynthesis and role of phosphorylcholine in pathogenic and nonpathogenic bacteria

Phosphorylcholine (ChoP) can be found in all life forms. Although this molecule was first thought to be uncommon in bacteria, it is now appreciated that many bacteria express ChoP on their surface. ChoP is usually attached to a glycan structure, but in some cases, it is added as a post-translational modification to proteins. Recent findings have demonstrated the role of ChoP modification and phase variation (ON/OFF switching) in bacterial pathogenesis. However, the mechanisms of ChoP synthesis are still unclear in some bacteria. Here, we review the literature and examine the recent developments in ChoP-modified proteins and glycolipids and of ChoP biosynthetic pathways. We discuss how the well-studied Lic1 pathway exclusively mediates ChoP attachment to glycans but not to proteins. Finally, we provide a review of the role of ChoP in bacterial pathobiology and the role of ChoP in modulating the immune response.

Phosphorylcholine-conjugated gold-molecular clusters improve signal for Lymph Node NIR-II fluorescence imaging in preclinical cancer models

Sentinel lymph node imaging and biopsy is important to clinical assessment of cancer metastasis, and novel non-radioactive lymphographic tracers have been actively pursued over the years. Here, we develop gold molecular clusters (Au₂₅) functionalized by phosphorylcholine (PC) ligands for NIR-II (1000–3000 nm) fluorescence imaging of draining lymph nodes in 4T1 murine breast cancer and CT26 colon cancer tumor mouse models. The Au-phosphorylcholine (Au-PC) probes exhibit ‘super-stealth’ behavior with little interactions with serum proteins, cells and tissues in vivo, which differs from the indocyanine green (ICG) dye. Subcutaneous injection of Au-PC allows lymph node mapping by NIR-II fluorescence imaging at an optimal time of ~ 0.5 − 1 hour postinjection followed by rapid renal clearance. Preclinical NIR-II fluorescence LN imaging with Au-PC affords high signal to background ratios and high safety and biocompatibility, promising for future clinical translation.

Fluorescent tracers facilitate the identification and subsequent collection of tumour draining lymph node biopsies, enabling important clinical assessment. Here, the authors present a molecular gold nanocluster NIR-II fluorescent imaging probe and demonstrate its utility to visualise draining lymph nodes in breast and colon cancer mouse models.

Bio-inspired special wettability in oral antibacterial applications

Most oral diseases originate from biofilms whose formation is originated from the adhesion of salivary proteins and pioneer bacteria. Therefore, antimicrobial materials are mainly based on bactericidal methods, most of which have drug resistance and toxicity. Natural antifouling surfaces inspire new antibacterial strategies. The super wettable surfaces of lotus leaves and fish scales prompt design of biomimetic oral materials covered or mixed with super wettable materials to prevent adhesion. Bioinspired slippery surfaces come from pitcher plants, whose porous surfaces are infiltrated with lubricating liquid to form superhydrophobic surfaces to reduce the contact with liquids. It is believed that these new methods could provide promising directions for oral antimicrobial practice, improving antimicrobial efficacy.

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.

Cell-repellent polyampholyte for conformal coating on microstructures

Repellent coatings are critical for the development of biomedical and analytical devices to prevent nonspecific protein and cell adhesion. In this study, prevelex (polyampholytes containing phosphate and amine units) was synthesized for the fine coating of microdevices for cell culture. The dip-coating of the prevelex on hydrophobic substrates altered their surfaces to be highly hydrophilic and electrically neutral. The range of prebake temperature (50–150 °C) after dip-coating was moderate and within a preferable range to treat typical materials for cell culture such as polystyrene and polydimethylsiloxane. Scanning electron microscopy revealed a conformal and ultra-thin film coating on the micro/nano structures. When compared with poly(2-hydroxyethyl methacrylate) and poly(2-methacryloyloxyethyl phosphorylcholine), prevelex exhibited better characteristics for coating on microwell array devices, thereby facilitating the formation of spheroids with uniform diameters using various cell types. Furthermore, to examine cellular functionalities, mouse embryonic epithelial and mesenchymal cells were seeded in a prevelex-coated microwell array device. The two types of cells formed hair follicle germ-like aggregates in the device. The aggregates were then transplanted to generate de novo hair follicles in nude mice. The coating material provided a robust and fine coating approach for the preparation of non-fouling surfaces for tissue engineering and biomedical applications.

Enhanced antimicrobial and remineralizing properties of self-adhesive orthodontic resin containing mesoporous bioactive glass and zwitterionic material

Abstract Background/purpose

Self-adhesive resins (SARs) do not require additional restorative adhesives and provide adequate adhesion to mineralized dental structures by shortening the bonding time in clinics where moisture control and isolation are difficult. The aim of this study was to evaluate the mechanical and biological properties of SARs containing mesoporous bioactive glass nanoparticles (MBNs) and 2-methacryloyloxyethyl phosphorylcholine (MPC) and to determine their antibacterial and remineralization effects.

Materials and methods

MBNs and MPC were added to SARs to improve their physical properties and remineralization ability. The experimental resins assessed in this study were SARs mixed with 3%MPC, 5%MPC, 1%MBN+3%MPC, or 3%MBN+3%MPC. The shear bond strength, microhardness, adhesive remnant index, ion dissolution, degree of conversion, and antibacterial properties of the SARs were evaluated. To assess the remineralization properties, micro-computed tomography analysis was performed after pH cycling.

Results

Increasing the MBN content in SAR resulted in higher microhardness compared to the control SAR. The shear bond strength decreased in the SAR+5%MPC group and increased in the SAR+1%MBN+3%MPC and SAR+3%MBN+5%MPC groups.

Conclusion

Our findings suggest that SARs containing MBNs and MPC have antibacterial and remineralization effects on the enamel.

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.

Zwitterionic Block Copolymer Prodrug Micelles for pH Responsive Drug Delivery and Hypoxia-Specific Chemotherapy

Tirapazamine (TPZ) and its derivatives (TPZD) have shown their great potential for efficiently killing hypoxic cancer cells. However, unsatisfactory clinical outcomes resulting from the low bioavailability of the low-molecular TPZ and TPZD limited their further applications. Precise delivery and release of these prodrugs via functional nanocarriers can significantly improve the therapeutic effects due to the targeted drug delivery and enhanced permeability and retention (EPR) effect. Herein, zwitterionic block copolymer (BCP) micelles with aldehyde functional groups are prepared from the self-assembly of poly(2-methacryloyloxyethyl phosphorylcholine-b-poly(di(ethylene glycol) methyl ether methacrylate-co-4-formylphenyl methacrylate) [PMPC-b-P(DEGMA-co-FPMA)]. TPZD is then grafted onto PMPC-b-P(DEGMA-co-FPMA) to obtain a polymer-drug conjugate, PMPC-b-P(DEGMA-co-FPMA-g-TPZD) (BCP-TPZ), through the formation of a pH-responsive imine bond, exhibiting a pH-dependent drug release profile owing to the cleavage of the imine bond under acidic conditions. Outstandingly, BCP-TPZ shows around 13.7-fold higher cytotoxicity to hypoxic cancer cells in comparison to normoxic cancer cells evaluated through an in vitro cytotoxicity assay. The pH-responsiveness and hypoxia-specific cytotoxicity confer BCP-TPZ micelles a great potential to achieve precise delivery of TPZD and thus enhance the therapeutic effect toward tumor-hypoxia.

Recent Advances in the Development of Antimicrobial and Antifouling Biocompatible Materials for Dental Applications

The risk of secondary bacterial infections resulting from dental procedures has driven the design of antimicrobial and antifouling dental materials to curb pathogenic microbial growth, biofilm formation and subsequent oral and dental diseases. Studies have investigated approaches based primarily on contact-killing or release-killing materials. These materials are designed for addition into dental resins, adhesives and fillings or as immobilized coatings on tooth surfaces, titanium implants and dental prosthetics. This review discusses the recent developments in the different classes of biomaterials for antimicrobial and antifouling dental applications: polymeric drug-releasing materials, polymeric and metallic nanoparticles, polymeric biocides and antimicrobial peptides. With modifications to improve cytotoxicity and mechanical properties, contact-killing and anti-adhesion materials show potential for incorporation into dental materials for long-term clinical use as opposed to short-lived antimicrobial release-based coatings. However, extended durations of biocompatibility testing, and adjustment of essential biomaterial features to enhance material longevity in the oral cavity require further investigations to confirm suitability and safety of these materials in the clinical setting. The continuous exposure of dental restorative and regenerative materials to pathogenic microbes necessitates the implementation of antimicrobial and antifouling materials to either replace antibiotics or improve its rational use, especially in the day and age of the ever-increasing problem of antimicrobial resistance.

Recent Progress in Antimicrobial Strategies for Resin-Based Restoratives

Repairing tooth defects with dental resin composites is currently the most commonly used method due to their tooth-colored esthetics and photocuring properties. However, the higher than desirable failure rate and moderate service life are the biggest challenges the composites currently face. Secondary caries is one of the most common reasons leading to repair failure. Therefore, many attempts have been carried out on the development of a new generation of antimicrobial and therapeutic dental polymer composite materials to inhibit dental caries and prolong the lifespan of restorations. These new antimicrobial materials can inhibit the formation of biofilms, reduce acid production from bacteria and the occurrence of secondary caries. These results are encouraging and open the doors to future clinical studies on the therapeutic value of antimicrobial dental resin-based restoratives. However, antimicrobial resins still face challenges such as biocompatibility, drug resistance and uncontrolled release of antimicrobial agents. In the future, we should focus on the development of more efficient, durable and smart antimicrobial dental resins. This article focuses on the most recent 5 years of research, reviews the current antimicrobial strategies of composite resins, and introduces representative antimicrobial agents and their antimicrobial mechanisms.

Use of catheter with 2-methacryloyloxyethyl phosphorylcholine polymer coating is associated with long-term availability of central venous port

Central venous port (CVP) is a widely used totally implantable venous access device. Recognition of risks associated with CVP-related complications is clinically important for safe, reliable, and long-term intravenous access. We therefore investigated factors associated with CVP infection and evulsion, including the device type. A total of 308 consecutive patients with initial CVP implantation between January 2011 and December 2017 were retrospectively reviewed, and the association of clinical features with CVP-related complications were analyzed. Intraoperative and postoperative complications occurred in 11 (3.6%) and 39 (12.7%) patients, respectively. The overall rate of CVP availability at six months was 91.4%. Malignancy and 2-Methacryloyloxyethyl phosphorylcholine (MPC) polymer-coated catheter use were negatively associated with the incidence of CVP infections. Accordingly, malignancy and MPC polymer-coated catheter use were independent predictors for lower CVP evulsion rate (odds ratio, 0.23 and 0.18, respectively). Furthermore, both factors were significantly associated with longer CVP availability (hazard ratio, 0.24 and 0.27, respectively). This retrospective study identified factors associated with CVP-related complications and long-term CVP availability. Notably, MPC polymer-coated catheter use was significantly associated with a lower rate of CVP infection and longer CVP availability, suggesting the preventive effect of MPC coating on CVP infection.

Use of Protein Repellents to Enhance the Antimicrobial Functionality of Quaternary Ammonium Containing Dental Materials

An advancement in preventing secondary caries has been the incorporation of quaternary ammonium containing (QAC) compounds into a composite resin mixture. The permanent positive charge on the monomers allows for electrostatic-based killing of bacteria. Spontaneous adsorption of salivary proteins onto restorations dampens the antimicrobial capabilities of QAC compounds. Protein-repellent monomers can work with QAC restorations to achieve the technology's full potential. We discuss the theory behind macromolecular adsorption, direct and indirect characterization methods, and advances of protein repellent dental materials. The translation of protein adsorption to microbial colonization is covered, and the concerns and fallbacks of the state-of-the-art protein-resistant monomers are addressed. Last, we present new and exciting avenues for protein repellent monomer design that have yet to be explored in dental materials.

Phospholipid Polymer Hydrogel Matrices with Dually Immobilized Cytokines for Accelerating Secretion of the Extracellular Matrix by Encapsulated Cells

Construction of 3D tissues by various types of cells with specific characteristics is an important and fundamental technology in tissue reconstruction medicine and animal-free diagnosis system. To do so, an excellent extracellular matrix (ECM) is needed for encapsulation of cells and maintaining cell activity. Spontaneously forming hydrogel matrix is used by complexation between two water-soluble polymers, 2-methacryloyloxyethyl phosphorylcholine polymer bearing phenylboronic acid groups and poly(vinyl alcohol). Two cytokines for cell proliferation are immobilized in the hydrogel matrix to control the activities of the encapsulated cells. The cytokine-immobilized hydrogel matrix can encapsulate both L929 fibroblasts and normal human dermal fibroblasts under mild condition. The physical properties of the hydrogel matrix can follow the proliferation process of the encapsulated cells. The encapsulated cells secrete ECM in the polymer hydrogel networks upon 3D culturing for 7 days. Consequently, the tissue-mimicking ECM hybrid hydrogels are fabricated successfully.

Suppressive effects of 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer on the adherence of Candida species and MRSA to acrylic denture resin

Objectives

The effects of 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer on the adherence of microorganisms such as non-Candida albicans Candida (NCAC) and methicillin-resistant Staphylococcus aureus (MRSA), frequently detected in oral infections in immunocompromised and/or elderly people, to denture resin material, are still unclear. Here, we report the effects of MPC-polymer on the adherence of C. albicans, NCAC, and MRSA to acrylic denture resin.

Methods

Sixteen strains of C. albicans, seven strains of C. glabrata, two strains of C. tropicalis, one strain of C. parapsilosis, and six strains of MRSA were used. We cultured the fungal/bacterial strains and examined the cell growth and adherence of fungi/bacteria to mucin-coated acrylic denture resin plates (ADRP) with or without MPC-polymer coating, by scanning electron microscopy. The cell surface hydrophobicity of the fungal/bacterial strains was measured by the adsorption to hydrocarbons.

Results

MPC-polymer did not affect the growth of all strains of Candida species and MRSA, but significantly suppressed adherence to ADRP in most strains of C. albicans and all strains of NCAC and MRSA. A significant positive correlation was found between cell hydrophobicity and the reduction rates of microbial adherence to ADRP treated with 5% of MPC-polymer.

Conclusions

MPC-polymer treatment for acrylic resin material suppresses the adherence of C. albicans, NCAC and MRSA via their hydrophilicity interaction.

Clinical significance

The application of MPC-polymer for denture hygiene is potent to prevent oral candidiasis, denture stomatitis and opportunistic infection, caused by Candida species and MRSA, via suppressing the adherence of those fungus/bacteria.

Hybridization of a phospholipid polymer hydrogel with a natural extracellular matrix using active cell immobilization

Three-dimensional tissue organization is still an obstacle in the field of tissue engineering, which generally involves cell immobilization, proliferation, and organization. As an artificial extracellular matrix (ECM) for providing a suitable environment of cells to construct tissues, combination of cytocompatible polymer hydrogels and natural ECM produced by the immobilized cells was considered. In this research, we designed a spontaneously forming hydrogel system between two water-soluble polymers for the immobilization of cells. These polymers were poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate-co-p-vinylphenylboronic acid-co-N-succinimidyloxycarbonyl tetra(ethylene glycol)methacrylate) (PMBVS) and poly(vinyl alcohol) (PVA) to form a PMBVS/PVA hydrogel in a cell culture medium under mild conditions. Basic fibroblast growth factor (bFGF) was conjugated with PMBVS (PMBV-bFGF). To enhance the growth of the immobilized cells, mouse fibroblast L929 cells were immobilized in the PMBVS/PVA hydrogel and the PMBV-bFGF/PVA hydrogel, and their proliferation and secretion of the ECM under stimulation with bFGF was observed. The ECM infiltrated and replaced the hydrogel, resulting in the formation of a hybrid hydrogel with the ECM and laden cells.

Zwitterionic Nanocellulose-Based Membranes for Organic Dye Removal

The development of efficient and environmentally-friendly nanomaterials to remove contaminants and pollutants (including harmful organic dyes) ravaging water sources is of major importance. Herein, zwitterionic nanocomposite membranes consisting of cross-linked poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and bacterial nanocellulose (BNC) were prepared and tested as tools for water remediation. These nanocomposite membranes fabricated via the one-pot polymerization of the zwitterionic monomer, 2-methacryloyloxyethyl phosphorylcholine, within the BNC three-dimensional porous network, exhibit thermal stability up to 250 °C, good mechanical performance (Young's modulus ≥ 430 MPa) and high water-uptake capacity (627%-912%) in different pH media. Moreover, these zwitterionic membranes reduced the bacterial concentration of both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) pathogenic bacteria with maxima of 4.3- and 1.8-log CFU reduction, respectively, which might be a major advantage in reducing or avoiding bacterial growth in contaminated water. The removal of two water-soluble model dyes, namely methylene blue (MB, cationic) and methyl orange (MO, anionic), from water was also assessed and the results demonstrated that both dyes were successfully removed under the studied conditions, reaching a maximum of ionic dye adsorption of ca. 4.4-4.5 mg g-1. This combination of properties provides these PMPC/BNC nanocomposites with potential for application as antibacterial bio-based adsorbent membranes for water remediation of anionic and cationic dyes.