Synthesis of biomembrane-mimic polymers with various phospholipid head groups

Dual-Polymer Functionalized Melanin-AgNPs Nanocomposite with Hydroxyapatite Binding Ability to Penetrate and Retain in Biofilm Sequentially Treating Periodontitis

Periodontitis is the leading cause of adult tooth missing. Thorny bacterial biofilm and high reactive oxygen species (ROS) levels in tissue are key elements for the periodontitis process. It is meaningful to develop an advanced therapeutic system with sequential antibacterial/ antioxidant ability to meet the overall goals of periodontitis therapy. Herein, a dual-polymer functionalized melanin-AgNPs (P/D-MNP-Ag) with biofilm penetration, hydroxyapatite binding, and sequentially treatment ability are fabricated. Polymer enriched with 2-(Dimethylamino)ethyl methacrylate (D), can be protonated in an acid environment with enhanced positive charge, promoting penetration in biofilm. The other polymer is rich in phosphate group (P) and can chelate Ca2+, promoting the polymer to adhere to the hydroxyapatite surface. Melanin has good ROS scavenging and photothermal abilities, after in situ reduction Ag, melanin-AgNPs composite has sequentially transitioned between antibacterial and antioxidative ability due to heat and acid accelerated Ag+ release. The released Ag+ and heat have synergistic antibacterial effects for bacterial killing. With Ag+ consumption, the antioxidant ability of MNP recovers to scavenge ROS in the inflammatory area. When applied in the periodontitis model, P/D-MNP-Ag has good therapeutical effects to ablate biofilm, relieve inflammation state, and reduce alveolar bone loss. P/D-MNP-Ag with sequential treatment ability provides a reference for developing advanced oral biofilm eradication systems.

Phosphorylated Polyesters Inspired by Phospholipids: Synthesis, Characterization, and Potential Applications

We report the synthesis of phosphorylated polyesters by the phosphorylation of hydroxylated polyesters synthesized by the lipase-catalyzed polycondensation of glycerol and aliphatic dicarboxylic acids and their characterization. The use of phosphoryl chloride as a phosphorylating agent and triethylamine as a catalyst in mild reaction conditions resulted in polyesters with repetitive units structurally similar to phospholipids, molar mass of around 14-38 kDa, and a degree of phosphorylation of 36 ± 11 mol %. These polyesters are composed mainly of 10 different repetitive units as determined by 1D and 2D NMR. Their properties change from more hydrophilic and amorphous for phosphorylated poly(glycerol adipate) to more hydrophobic and semicrystalline for phosphorylated poly(glycerol dodecanedioate). Preliminary investigations have shown the potential of these polyesters to self-assemble in aqueous media forming nanoparticles, which can be loaded with hydrophobic molecules and released into an organic phase, acting as a phase transfer agent, and used as a pH-responsive emulsifier.

Alleviation of Surgery-Induced Osteitis in Sinonasal Cavity by Dexamethasone-Loaded Poly(lactic-co-glycolic acid) (PLGA) Microparticles with Strong Calcium-Binding Affinity

For the treatment of sinus surgery-induced osteitis in chronic rhinosinusitis (CRS), oral or intranasal administration of corticoids is generally used, although it has critical limitations and unavoidable side effects. To overcome these limitations, we designed dexamethasone (Dex)-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles with bone-specific binding affinity, which could release the encapsulated Dex in a sustained manner on the exposed bone after the surgical wound in the nasal cavity. In a previous report, we prepared poly(butyl methacrylate-co-methacryloyloxyethyl phosphate) (PBMP) with both calcium-binding phosphomonoester groups and PLGA-binding butyl groups to introduce strong calcium-binding property to PLGA particles. In this study, after successful encapsulation of Dex in the PBMP-coated PLGA particles, we applied the Dex-PLGA/PBMP to the treatment of post-operative osteitis in the sinonasal cavity. The Dex-PLGA/PBMP showed more than 5-times higher binding affinity to the hydroxyapatite (HA) surface compared to the non-coated PLGA particles, without altering the morphology and encapsulation efficiency. After establishing the neo-osteogenesis mouse model by mechanical injury of the nasal mucosa, the activity of intranasally administered Dex-PLGA/PBMP was examined to inhibit the formation of undesirable new woven bone during the wound healing process. In addition, significantly lower osteocalcin activity was observed in the group treated with Dex-PLGA/PBMP, indicating decreased activation of osteoblasts. Overall, these results demonstrate that the PLGA/PBMP microparticle strategy has great potential for the treatment of CRS-related osteitis by localized corticoid delivery on the exposed bones with minimal side effects.

Assessment of human adipose-derived stem cell on surface-modified silicone implant to reduce capsular contracture formation

Medical devices made from poly(dimethylsiloxane) (PDMS)-based silicone implants have been broadly used owing to their inert properties, biocompatibility, and low toxicity. However, long-term implantation is usually associated with complications, such as capsular contracture due to excessive local inflammatory response, subsequently requiring implant removal. Therefore, modification of the silicone surface to reduce a risk of capsular contracture has attracted increasing attention. Human adipose-derived stem cells (hASCs) are known to provide potentially therapeutic applications for tissue engineering, regenerative medicine, and reconstructive surgery. Herein, hASCs coating on a PDMS (hASC-PDMS) or itaconic acid (IA)-conjugated PDMS (hASC-IA-PDMS) surface is examined to determine its biocompatibility for reducing capsular contracture on the PDMS surface. In vitro cell cytotoxicity evaluation showed that hASCs on IA-PDMS exhibit higher cell viability than hASCs on PDMS. A lower release of proinflammatory cytokines is observed in hASC-PDMS and hASC-IA-PDMS compared to the cells on plate. Multiple factors, including in vivo mRNA expression levels of cytokines related to fibrosis; number of inflammatory cells; number of macrophages and myofibroblasts; capsule thickness; and collagen density following implantation in rats for 60 days, indicate that incorporated coating hASCs on PDMSs most effectively reduces capsular contracture. This study demonstrates the potential of hASCs coating for the modification of PDMS surfaces in enhancing surface biocompatibility for reducing capsular contracture of PDMS-based medical devices.

Calcium-Binding Polymer-Coated Poly(lactide- co-glycolide) Microparticles for Sustained Release of Quorum Sensing Inhibitors to Prevent Biofilm Formation on Hydroxyapatite Surfaces

Quorum sensing (QS) inhibitor-based therapy is an attractive strategy to inhibit bacterial biofilm formation without excessive induction of antibiotic resistance. Thus, we designed Ca²⁺-binding poly(lactide- co-glycolide) (PLGA) microparticles that can maintain a sufficient concentration of QS inhibitors around hydroxyapatite (HA) surfaces in order to prevent biofilm formation on HA-based dental or bone tissues or implants and, therefore, subsequent pathogenesis. Poly(butyl methacrylate- co-methacryloyloxyethyl phosphate) (PBMP) contains both Ca²⁺-binding phosphomonoester groups and PLGA-interacting butyl groups. The PBMP-coated PLGA (PLGA/PBMP) microparticles exhibited superior adhesion to HA surfaces without altering the sustained release properties of uncoated PLGA microparticles. PLGA/PBMP microparticle-encapsulating furanone C-30, a representative QS inhibitor, effectively inhibited the growth of Streptococcus mutans and its ability to form biofilms on HA surface for prolonged periods of up to 100 h, which was much longer than either furanone C-30 in its free form or when encapsulated in noncoated PLGA microparticles.

Extended wear therapeutic contact lens fabricated from timolol imprinted carboxymethyl chitosan-g-hydroxy ethyl methacrylate-g-poly acrylamide as a onetime medication for glaucoma

An extended wear therapeutic contact lens (TCL) for the sustained delivery of timolol maleate (TML) was fabricated based on molecular imprinting technique. The designed TCL comprised of a TML imprinted copolymer of carboxymethyl chitosan-g-hydroxy ethyl methacrylate-g-polyacrylamide (CmCS-g-HEMA-g-pAAm) embedded onto a poly HEMA matrix (pHEMA). Successful reloading of TML onto the lens was monitored using a simple and novel UV-Visible spectrophotometric method which showed an excellent reloading capacity of 6.53μgTML/TCL. The in vitro drug release profile in lacrimal fluid after each cycle was fitted onto Higuchi model of drug release suggesting diffusion release mechanism with no polymer degradation. Also, the TML release kinetics indicated a sustained drug delivery which can effectively achieve the therapeutic index of TML leading to a onetime medication for glaucoma. Biological activity of eluted drug after each cycle and cell viability of the TCL were verified using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,3-bis(2-methoxynitro-5-sulfophenyl)-5-(phenylaminocarbonyl)-2H-tetrazolium hydroxide (XTT) assay, respectively.

Development of anti-biofouling interface on hydroxyapatite surface by coating zwitterionic MPC polymer containing calcium-binding moieties to prevent oral bacterial adhesion

The purpose of the present study is to synthesize a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer capable of being immobilized on the tooth surface to prevent oral bacterial adhesion. The strategy is to develop an MPC-based polymer with Ca(2+)-binding moieties, i.e., phosphomonoester groups, for stronger binding with hydroxyapatite (HA) of the tooth surface. To this end, a 2-methacryloyloxyethyl phosphate (MOEP) monomer was synthesized and copolymerized with MPC by free radical polymerization. The coating efficiency of the synthesized polymer, MPC-ran-MOEP (abbreviated as PMP) with varied composition, onto a HA surface was estimated by means of contact angle measurement and X-ray photoelectron spectroscopy. The anti-biofouling nature of PMP-coated HA surfaces was estimated by analyzing protein adsorption, cell adhesion, and Streptococcus mutans adhesion. As a result, HA surface coated with a copolymer containing around 50% MPC (PMP50) showed the best performance in preventing protein adsorption and the downstream cell and bacterial adhesion.

STATEMENT OF SIGNIFICANCE

Preparation of anti-biofouling surface on the tooth enamel is the key technique to prevent dental and periodontal diseases, which are closely related with the biofilm formation that induced by the adsorption of salivary proteins and the adhesion of oral bacteria on the tooth surface. In this research, a PMP copolymer with an optimized ratio of zwitterionic and Ca(2+)-binding moieties could form a highly effective and robust anti-biofouling surface on HA surfaces by a simple coating method. The PMP-coated surface with high stability can provide a new strategy for an anti-adsorptive and anti-bacterial platform in dentistry and related fields.

Alleviation of capsular formations on silicone implants in rats using biomembrane-mimicking coatings

Despite their popular use in breast augmentation and reconstruction surgeries, the limited biocompatibility of silicone implants can induce severe side effects, including capsular contracture - an excessive foreign body reaction that forms a tight and hard fibrous capsule around the implant. This study examines the effects of using biomembrane-mimicking surface coatings to prevent capsular formations on silicone implants. The covalently attached biomembrane-mimicking polymer, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), prevented nonspecific protein adsorption and fibroblast adhesion on the silicone surface. More importantly, in vivo capsule formations around PMPC-grafted silicone implants in rats were significantly thinner and exhibited lower collagen densities and more regular collagen alignments than bare silicone implants. The observed decrease in α-smooth muscle actin also supported the alleviation of capsular formations by the biomembrane-mimicking coating. Decreases in inflammation-related cells, myeloperoxidase and transforming growth factor-β resulted in reduced inflammation in the capsular tissue. The biomembrane-mimicking coatings used on these silicone implants demonstrate great potential for preventing capsular contracture and developing biocompatible materials for various biomedical applications.