Phosphorylcholine Polymer Research Articles

Incorporation of zwitterionic materials into light-curable fluoride varnish for biofilm inhibition and caries prevention

We incorporated zwitterionic materials into light-curable fluoride varnish (LCFV) in order to inhibit biofilm accumulation and prevent dental caries, and the properties of LCFV with three different zwitterionic materials, namely, 2-methacryloyloxyethyl phosphorylcholine (MPC), carboxybetaine methacrylate (CBMA), and sulfobetaine methacrylate (SBMA) polymers (each at a weight percentage of 3%), were compared; unmodified LCFV without any zwitterionic material was used as a control. Material properties including film thickness and degree of conversion (DC) of each type of LCFV were evaluated. In addition, protein-repellent effects and inhibitory effects on Streptococcus mutans adhesion and saliva-derived biofilm accumulation of LCFV were estimated. Finally, the preventive effect of LCFV on enamel demineralization was assessed in vitro on extracted human teeth specimens stored in S. mutans-containing medium. The film thickness of LCFV significantly decreased with the incorporation of zwitterionic materials compared to the control LCFV, whereas there were no significant differences in the DC among all of the LCFV groups. Furthermore, the amount of adsorbed protein, adherent S. mutans colony-forming unit (CFU) counts, and saliva-derived biofilm thickness and biomass were all significantly lower for LCFV with incorporated zwitterionic materials compared with the control. All LCFV groups including the control showed certain preventive effects against enamel demineralization during a 14-day immersion in the medium with S. mutans and sucrose, and the depth of demineralization was significantly lower in LCFV with zwitterionic materials than in the control. Thus, the incorporation of zwitterionic materials such as MPC, CBMA, and SBMA appears to confer superior antifouling effects to LCFV.

Surface-Functionalized Polypropylene Surgical Mesh for Enhanced Performance and Biocompatibility.

Polypropylene (PP) surgical mesh has attracted vast attention due to its chemical inertness and excellent mechanical properties. However, improvement is necessary to enhance its biocompatibility and to prevent unwanted tissue adhesion. This study addresses these issues through surface modification of plasma-activated PP mesh with a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. Reaction time and monomer concentration have been optimized to achieve the optimal biocompatibility with reduction in protein adsorption. Attenuated total reflection-Fourier transform infrared spectra confirmed the grafting of the MPC polymer (PMPC) to the plasma-activated polypropylene (PPP) mesh. Scanning electron microscopy images and energy-dispersive X-ray (EDX) line spectra exhibited morphological changes and specifically PMPC grafting to the surface of PPP mesh, due to the presence of a significant amount of phosphorus (P) on the grafted PPP mesh. PMPC-grafted polypropylene (PPP-PMPC) showed a significant reduction in contact angle as well as the amount of adsorbed bovine serum albumin (BSA) protein in comparison with pristine PP mesh. The highest reduction in protein adsorption and the lowest contact angle were achieved at the monomer concentration of 0.3 M and the reaction time of 90 min. A longer reaction time and higher monomer concentration resulted in clogging within the mesh pores. MTT assay results (∼90% cell viability) confirmed the nontoxicity of the PMPC-grafted mesh, while optical microscopic and SEM images showed increased resistance of cell attachment to the surface of PMPC-grafted mesh. The results show that PPP-PMPC can be a promising biomaterial to address the current issues in biocompatibility and reduction in adhesion after surgery.

Synthesis and characterizations of zwitterionic copolymer hydrogels with excellent lubrication behavior

Abstract Various studies on hydrogel applications as cartilage substitutes and artificial joints have been previously conducted. In this study, a copolymer hydrogel comprising zwitterionic sulfobetaine methacrylate (SBMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers is synthesized in an aqueous system via free-radical polymerization. A P(MPC-co-SBMA) copolymer hydrogel network is formed via the additional polymerization of the alkane carbon–carbon double bond from the combination of MPC and SBMA polymer chains using ethylene glycol dimethacrylate (EGDMA) as the crosslinker. Introduction of MPC in the PSBMA hydrogel under water lubrication improved the compressive stress by almost double and considerably lowered the coefficient of friction (COF) to approximately 0.011. This phenomenon was attributed to the fact that MPC could intertwine with SBMA to increase the crosslink density of the hydrogel and preferentially adhere to the water to reduce the adhesion of the contact between hydrogels, leading to an intertwined copolymer network structure with excellent load-bearing capacity and superior hydration lubrication capability. This study might provide potentially useful information relating to cartilage replacement applications requiring high mechanical strength and excellent friction behavior.

Three-year major clinical outcomes of phosphorylcholine polymer- vs biolinx polymer-zotarolimus-eluting stents

There are limited long-term outcome data comparing BioLinx polymer (B)-zotarolimus-eluting stents (ZES) with phosphorylcholine polymer (P)-ZES. The aim of this study was to compare the efficacy and safety of B-ZES with P-ZES in patients who underwent percutaneous coronary intervention (PCI) during a 3-year follow-up period.One thousand two hundred fifty four patients who underwent PCI with P-ZES (Endeavor [ZES-E] or Endeavor sprint [ZES-S], n = 356) or B-ZES (Endeavor resolute [ZES-R] or Resolute Integrity [ZES-I], n = 889) were enrolled. The primary endpoint was major adverse cardiac events (MACE); the composite of total death, non-fatal myocardial infarction (MI), target lesion revascularization (TLR), target vessel revascularization (TVR), non-target vessel revascularization (Non-TVR), and the secondary endpoint was stent thrombosis (ST).After PSM, 2 propensity-matched (PSM) groups (275 pairs, n = 550, C-statistic = 0.730) were generated. During the 3-year follow-up period, the cumulative incidence of MACE (hazard ratio [HR], 1.525; 95% confidence interval [CI], 0.920-2.526; P = .101) and ST (HR, 1.248; 95% CI, 0.335-4.4649; P = .741) were similar between P-ZES and B-ZES after PSM. However, TLR rate was significantly higher in ZES-S than ZES-I (11.3% vs 3.8%, log rank P = .029) and TVR rate was higher in ZES-S than ZES-R (14.1% vs 4.8%, log rank P = .025).In this single-center, all-comer registry, despite different polymers, P-ZES, and B-ZES showed comparable safety and efficacy during a 3-year follow-up period after PCI.

In situ surface modification on dental composite resin using 2-methacryloyloxyethyl phosphorylcholine polymer for controlling plaque formation.

Composite resins (CRs) are widely used as dental restorative materials for caries treatment. They cause problems of secondary caries since Streptococcus mutans stays in the dental plaque, which the surface exists and produces acidic compounds during metabolism. The dental plaque depositions are induced by the protein adsorption on the surface. Therefore, suppression of protein adsorption on the surface of the CRs is important for inhibiting the formation of plaque and secondary caries. In this study we developed a surface treatment to provide an antibiofouling nature to the CRs by chemical reaction with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers in the oral cavity during dental treatment. To carry out the photochemical reaction on the remaining polymerizable groups of CRs, we synthesized the MPC polymer with a polymerizable group in the side chain. The MPC polymer could bind on the surfaces of the CRs chemically under dental treatment procedures. The treated surface showed significant resistance to oral protein adsorption and bacterial adhesion even when the surface was brushed with a toothbrush. Thus, we concluded that the photochemical reaction of the MPC polymer with the CRs in the oral cavity was good for making an antibiofouling surface and preventing secondary caries.

Evaluation of Modified Glass Ionomer Cements with Protein repellent and Nanostructured Antibacterial Properties in Prevention of Enamel Demineralization. An in vivo study

Objectives: To evaluate the in vivo effect of Titanium dioxide (TiO2) nanoparticles and methacryloyloxyethyl phosphoryl choline (MPC) polymer modifications of glass-ionomer cement, to inhibit demineralization around orthodontic bands. Materials and Methods: 60 orthodontic patients with non-carious molars scheduled for banding were randomly divided into three groups. Grouping was based on (3% MPC, 3% nano-Titanium, and 3%+3% of both by weight) added to the luting glass-ionomer cement (GIC) Medicem, which was used for cementation of prefabricated micro-etched orthodontic bands. Demineralization was recorded by using DiagnoDent pen (KaVo, Biberach, Germany) device. Statistical evaluation was performed with one way ANOA test. Results: Bands cemented with conventional GIC showed the highest bacterial scores in comparison to those cemented with MPC polymer and nano-titanium modified GICs. There was significant difference between teeth banded with 3% MPC, 3% nano-titanium, and 3% MPC + 3% nano-titanium modified GICs. Conclusions: Modification of the banding GIC with MPC polymer and nano-titanium revealed a positive effect on reducing white spots around orthodontic bands.

Tracing Difference: In Vitro and in Vivo Antitumor Property Comparison of pH-Sensitive Biomimetic Phosphorylcholine Micelles with Insensitive Micelles.

Although smart polymer micelles able to respond to the tumor acid microenvironment are potential anticancer drug carriers, fruitful clinical application of these carriers is inadequate. For the purpose of finding the origin of the unsatisfactory therapeutic efficacy of pH-sensitive drug carriers with tertiary amine groups, we newly designed and synthesized poly{α-[4-(diethylamino)methyl-1,2,3-triazol]-caprolactone-co-caprolactone}-b-poly(2-methacryloyloxyethyl phosphorylcholine) (PDCL-PMPC), a biomimetic phosphorylcholine polymer with pH-ensitive groups. PDCL-PMPC self-assembles into small and uniform micelles as its counterpart poly(caprolactone)-b-poly(2-methacryloyloxyethyl phosphorylcholine) (PCL-PMPC) without pH-sensitive groups. The in vitro and in vivo properties of PDCL-PMPC and PCL-PMPC micelles are investigated in detail. PDCL-PMPC micelles display obvious pH sensitivity by micelle change and fast drug release at pH 5, but the insensitive micelles do not. The internalization of PDCL-PMPC micelles by tumor cells is stronger than that of PCL-PMPC micelles. However, in comparison with the insensitive micelles, the pH-sensitive micelles present much shorter blood circulation time in pharmacokinetics and demonstrate worse accumulation in the tumor site in vivo study. As a result, DOX loaded PCL-PMPC micelles demonstrate much better antitumor efficiency than pH-sensitive micelles. Furthermore, DOX loaded PCL-PMPC micelles show similar therapeutic efficacy to DOX·HCl but with considerably lower side effects.

Revolutionary advances in 2-methacryloyloxyethyl phosphorylcholine polymers as biomaterials.

In the last 40 years, many strategies to fabricate biocompatible and antithrombogenic polymers have been proposed, especially in Japan. The development of one such polymers composed of 2-methacryloyloxyethyl phosphorylcholine unit, is described in this review, with specific examples of use in biomedical devices. These polymers are typically incorporated into other materials to effectively prevent unfavorable biological responses and reactions. For example, the polymers suppress protein adsorption and cell adhesion to materials in contact with plasma or whole blood, even in the absence of anticoagulant. These properties are due to the extreme hydrophilicity and electrically neutral nature of the polymers, as well as to the ability of phosphorylcholine to induce bulk-like behavior in surrounding waters. Accordingly, these polymers have been used worldwide to modify the surfaces and improve the overall biocompatibility of such medical devices as long-term implantable artificial organs. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 933-943, 2019.

Micropatterning of a 2-methacryloyloxyethyl phosphorylcholine polymer surface by hydrogenated amorphous carbon thin films for endothelialization and antithrombogenicity

The existing first-generation drug-eluting stent (DES) has caused late and very late stent thrombosis related to incomplete stent endothelialization. Hence, biomaterials that possess sufficient anti-thrombogenicity and endothelialization with the controlled drug release system have been highly required. In this work, we have developed a newly designed drug-release platform composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, a non-thrombogenic polymer, and micropatterned hydrogenated amorphous carbon (a-C:H), a cell-compatible thin film. The platelet adhesion and the endothelial cell adhesion behavior on the micropatterned substrates were investigated in vitro. The results indicated that the micropatterned a-C:H/MPC polymer substrates effectively supported the human umbilical vein endothelial cell (HUVEC) proliferation, while suppressing the platelet adhesion. Interestingly, the HUVEC exhibited different shape and behavior by changing the island size of the micropatterned a-C:H. By introducing both a non-thrombogenic polymer and cell-compatible thin films through a simple patterning method, we demonstrated that the platform had the potential to be utilized as a base material for DES with cell controllability. Statement of significanceThe current first-generation drug-eluting stents (DES) would cause late and very late stent thrombosis due to the incomplete endothelialization of the metal stent material. In this work, we have developed a new DES platform composed of a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer micropatterned by hydrogenated amorphous carbon (a-C:H). Two types of differently micropatterned a-C:H stent surface were made. Our studies revealed that the micropatterned a-C:H/MPC polymer substrates could effectively enhance the endothelial cell (EC) proliferation, simultaneously suppressing the platelet adhesion, becoming a highly biocompatible material especially for indwelling devices including a drug-release device. The new drug-release platform could be utilized as a base material for cell-controllable coating on DES.

Effect of grafted poly [2-methacryloyloxyethyl phosphorylcholine (MPC)] on tribological properties of ultra-high molecular weight polyethylene (UHMWPE)

2-methacryloyloxyethyl phosphorylcholine (MPC) polymers have good biocompatibility and hydrophilicity because the function of the phospholipid polar groups of MPC side-chain is similar to the natural articular cartilage. MPC has a potential application on surface modification of artificial joints. In this research, MPC was grafted on ultra-high molecular weight polyethylene (UHMWPE) by the photo-induced graft polymerization to form poly 2-methacryloyloxyethyl phosphorylcholine (PMPC) layer. The microstructure of PMPC layer was studied by Fourier-transform infrared (FT-IR) spectroscopy with attenuated total reflection (ATR) equipment, X-ray photoelectron spectroscopy (XPS). The surface wettability of PMPC layer was evaluated by the contact angle test. The wear resistance of MPC modified UHMWPE was evaluated by the wear test. The results show that the PMPC layer has a good lubricating effect and it can reduce the friction coefficient effectively. The benzophenone pretreatment time is an important factor in the graft stability of MPC.

Synthesis of a SN38 prodrug grafted to amphiphilic phosphorylcholine polymers and their prodrug miceller properties

Polymer prodrug micelles, combining the advantages of prodrugs and polymer micelles, can greatly improve the solubility, permeability and stability of drugs.

Solubilized eggshell membrane supplies a type III collagen-rich elastic dermal papilla

Signs of aging in facial skin correlate with lifespan and chronic disease; however, the health of aging skin has not been extensively studied. In healthy young skin, the dermis forms a type III collagen-rich dermal papilla, where capillary vessels supply oxygen and nutrients to basal epidermal cells. Chicken eggshell membranes (ESMs) have been used as traditional medicines to promote skin wound healing in Asian countries for many years. Previously, we designed an experimental system in which human dermal fibroblasts (HDFs) were cultured on a dish with a solubilized ESM (S-ESM) bound to an artificial phosphorylcholine polymer; we found that genes that promoted the health of the papillary dermis, such as those encoding type III collagen, were induced in the S-ESM environment. The present study found that a gel with a ratio of 20% type III/80% type I collagen, similar to that of the baby skin, resulted in a higher elasticity than 100% type I collagen (p < 0.05) and that HDFs in the gel showed high mitochondrial activity. Thus, we decided to perform further evaluations to identify the effects of S-ESM on gene expression in the skin of hairless mice and found a significant increase of type III collagen in S-ESM. Picrosirius Red staining showed that type III collagen significantly increased in the papillary dermis after S-ESM treatment. Moreover, S-ESM application significantly improved human arm elasticity and reduced facial wrinkles. ESMs may have applications in extending lifespan by reducing the loss of tissue elasticity through the increase of type III collagen.

Examination of 2-methacryloyloxyethyl phosphorylcholine polymer coated acrylic resin denture base material: surface characteristics and Candida albicans adhesion

The aim of this study is to evaluate the effects of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer coating with various concentrations onto acrylic resin denture base material on surface characteristics such as contact angle and surface roughness and on Candida albicans adhesion which is the major factor of denture stomatitis. Specimens, prepared from heat-polymerized acrylic denture base material, were divided into control and three test groups, randomly. Surfaces of the specimens in test groups were coated with poly(MPC) (PMPC) by graft polymerization of MPC in different concentrations (0.25 mol/L; 0.50 mol/L and 0.75 mol/L), while no surface treatment was applied to the control group. Contact angles and surface roughness were examined, and chemical composition of the surfaces was analyzed by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (FTIR) to verify the presence of PMPC coatings. Then, specimens were incubated with C. albicans for 18 h and the number of adhered cells was determined. Upon PMPC coating, the contact angle values statistically decreased, but no difference was found in surface roughness values. A statistically significant decrease was observed in C. albicans adhesion in parallel with the increase in the MPC polymer concentration. There was no significant difference between 0.50 mol/L and 0.75 mol/L groups in terms of adhesion. These findings indicated that graft polymerization of MPC on acrylic denture base material reduces the adhesion of C. albicans, and may be evaluated as a coating for prevention of denture stomatitis.

LC–MS analysis to determine the biodistribution of a polymer coated ilomastat ocular implant

Ilomastat is a matrix metalloproteinase inhibitor (MMPi) that has shown the potential to inhibit scarring (fibrosis) by mediating healing after injury or surgery. A long lasting ocular implantable pharmaceutical formulation of ilomastat is being developed to mediate the healing process to prevent scarring after glaucoma filtration surgery. The ilomastat implant was coated with water permeable and biocompatible phosphoryl choline polymer (PC1059) displayed extended slow release of ilomastat in vitro and in vivo. The ocular distribution of ilomastat from the implant in rabbits at day 30 post surgery was determined by the extraction of ilomastat and its internal standard marimastat from the ocular tissues, plasma, aqueous humour and vitreous fluid followed by capillary-flow liquid chromatography (cap-LC), the column effluent was directed into a triple quadrupole mass spectrometer operating in product scan mode. The lower limits of quantification (LLOQs) were 0.3 pg/μL for ocular fluids and plasma, and 3 pg/mg for ocular tissues. The extraction recoveries were 90–95% for ilomastat and its internal standard from ocular tissues. Ilomastat was found in ocular fluids and tissues at day 30 after surgery. The level of ilomastat was 18 times higher in the aqueous humour than vitreous humour. The concentration ranking of ilomastat in the ocular tissues was sclera > bleb conjunctiva > conjunctiva (rest of the eye) > cornea. Mass spectrometry analysis to confirm the presence of ilomastat in the ocular tissues and fluids at day 30 post-surgery establishes the extended release of ilomastat can be achieved in vivo, which is crucial information for optimisation of the ilomastat coated implant.

Highly hydrophilic and antibiofouling surface of zwitterionic polymer immobilized on polydimethylsiloxane by initiator-free atmospheric plasma-induced polymerization

In this study, we have successfully grafted zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer brushes (5–8 nm) on the silicone (polydimethylsiloxane, PDMS)-based contact lenses using “initiator-free” and atmospheric plasma-induced polymerization. Varied atmospheric plasmas (O2, N2 and Ar gas) were employed in the process of the polymerization of the zwitterionic polymer brushes on the silicone surfaces without the addition of any initiators. The morphology and characterization of the zwitterionic MPC-immobilized films were investigated using atomic force microscopy, contact angle (CA) measurements and X-ray photoelectron spectroscopy. MPC immobilizations will significantly improve the hydrophilicity of silicone contact lenses, and the CA of the MPC modified-silicone contact lenses will decrease to 50°–60°, compared with that of the pristine ones (CA: ~90°). Furthermore, the MPC modifications exhibit an anti-fouling capability (25–30% decrease of protein adsorption), which can avoid protein (fibrinogen and human serum bovine) adhesion that would contaminate the contact lenses. It maintains the great oxygen permeability (103 ± 5 Dk) and transmittance (T%) is still transparent and colorless after MPC grafted on the PDMS contact lens. Therefore, the immobilization of the MPC polymer brushes by atmospheric plasma-induced polymerization would be a rapid method to improve the hydrophilicity and enhance the anti-fouling capability of silicone based-contact lenses.

AB085. E-beam sterilization of recombinant human collagen-phosphorylcholine corneal implants for transplantation

Background: The sterilization of corneal implants composed of carbodiimide crosslinked recombinant human collagen type III (RHCIII) and phosphorylcholine polymers (RHCIII-MPC) is constrained by the biochemical properties of RHCIII. Early human trials used 1% chloroform in 0.1 M phosphate buffered saline (C-PBS), but require a stringent wash procedure with antibiotics to remove the chloroform. Irradiation with gamma or electron-beam (e-beam) allows a chemical-free sterilization method, but may result in crosslinking or denaturation. Here, electron-beam irradiation is evaluated as a sterilization method for RHCIII-MPC implants.

Correction to: The effect of cationically-modified phosphorylcholine polymers on human osteoblasts in vitro and their effect on bone formation in vivo.

The article "The effect of cationically modified phosphorylcholine polymers on human osteoblasts in vitro and their effect on bone formation in vivo", written by Jonathan M. Lawton, Mariam Habib, Bingkui Ma, Roger A. Brooks, Serena M. Best, Andrew L. Lewis, Neil Rushton and William Bonfield, was originally published Online First without open access. After publication in volume 28, issue 9, page 144 it was noticed that the copyright was wrong in the PDF version of the article. The copyright of the article should read as "

In vitro basic fibroblast growth factor (bFGF) delivery using an antithrombogenic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer coated with a micropatterned diamond-like carbon (DLC) film.

In this study, a newly designed drug-release platform composed of an antithrombogenic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer was introduced, which was impregnated with basic fibroblast growth factor (bFGF) (bFGF/MPC polymer) to enhance the endothelial cell activation. The platform was also coated with an ultrathin micropatterned diamond-like carbon (DLC) film (DLC/bFGF/MPC polymer) to precisely control the drug release rate and the cell compatibility. The resulting DLC/bFGF/MPC polymer could effectively prolong the bFGF release rate by depositing the micropatterned DLC. The number of adherent platelets on the DLC/bFGF/MPC polymer was significantly lower (about 1/14) than that on a currently used stent made of stainless steel (SUS316L), indicating the enhanced antithrombogenicity in the DLC/bFGF/MPC polymer. The proliferation of endothelial cells on the DLC/bFGF/MPC polymer and the DLC/MPC polymer (without bFGF) were also examined. It was found that the optical density of HUVEC on the DLC/bFGF/MPC polymer determined by WST-8 assay was higher by 25%than that on the DLC/MPC polymer (without bFGF) measured after 72 h of incubation. Our results suggest that the released bFGF that contributes to the expression of other growth factors results in the early proliferation of the HUVEC on the DLC/bFGF/MPC polymer. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3384-3391, 2017.

Well-defined protein immobilization on photo-responsive phosphorylcholine polymer surfaces

In this study, we propose a new polymer substrate that is able to covalently couple intended proteins and reduce nonspecific protein fouling. Poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-ran-N-methacryloyl-(L)-tyrosinemethylester (MAT)] [P(MPC/MAT)] was synthesized by free-radical polymerization. The photooxidation of the MAT unit in the copolymer was observed under ultraviolet (UV) light at 254 nm. P(MPC/MAT) was spin-coated on silicon (Si) and gold substrates. Without UV irradiation of the polymer-coated surface, P(MPC/MAT) physisorbed on the substrates, and the thickness of the polymer layer was less than 10 nm, regardless of the polymer concentration in the coating solution. In contrast, when the polymer-coated surface was irradiated with UV light, the thickness of the polymer layer could be controlled by changing the polymer concentration of the coating solution. Competitive protein adsorption on P(MPC/MAT) was studied. Bovine serum albumin was first contacted with the surface and later challenged with bovine fibrinogen. On bare gold and Si substrates, a large amount of albumin was adsorbed, and the competitive adsorption of albumin and fibronectin was observed. In contrast, the non-UV-irradiated P(MPC/MAT) surface effectively reduced protein adsorption. Interestingly, on the UV-irradiated P(MPC/MAT) surface, the primary protein preferably bonded, and significantly less secondary protein was adsorbed compared to primary protein. Cell adhesion was also tested on the substrate to clarify the effects of proteins existing on the substrates. On the bare Si surface, many adherent cells were observed, regardless of the protein pretreatment. On the non-UV-irradiated P(MPC/MAT) surface, cell adhesion was effectively reduced along with protein adsorption. Cell adhesion on the UV-irradiated P(MPC/MAT) surface depended strongly on the type of protein that was initially in contact with the surface. We concluded that the desired proteins could be immobilized on the photo-activated P(MPC/MAT) surface while preserving their function. Moreover, competitive protein exchange and multilayer adsorption hardly occurred on the surface.

The effect of cationically-modified phosphorylcholine polymers on human osteoblasts in vitro and their effect on bone formation in vivo

The effect of introducing cationic charge into phosphorylcholine (PC)-based polymers has been investigated in this study with a view to using these materials as coatings to improve bone formation and osseointegration at the bone-implant interface. PC-based polymers, which have been used in a variety of medical devices to improve biocompatibility, are associated with low protein adsorption resulting in reduced complement activation, inflammatory response and cell adhesion. However, in some applications, such as orthopaedics, good integration between the implant and bone is needed to allow the distribution of loading stresses and a bioactive response is required. It has previously been shown that the incorporation of cationic charge into PC-based polymers may increase protein adsorption that stimulates subsequent cell adhesion. In this paper, the effect of cationic charge in PC-based polymers on human osteoblasts (HObs) in vitro and the effect of these polymers on bone formation in the rat tibia was assessed. Increasing PC positive surface charge increased HOb cell adhesion and stimulated increased cell differentiation and the production of calcium phosphate deposits. However, when implanted in bone these materials were at best biotolerant, stimulating the production of fibrous tissue and areas of loosely associated matrix (LAM) around the implant. Their development, as formulated in this study, as bone interfacing implant coatings is therefore not warranted.Graphical abstract