Hydrophobic modification of polymethyl methacrylate as intraocular lenses material to improve the cytocompatibility

Surface modification of commercial intraocular lens by zwitterionic and antibiotic-loaded coating for preventing postoperative endophthalmitis

After cataract surgery, to prevent possible postoperative endophthalmitis (POE) caused by attached pathogenic bacteria onto the surface of implanted intraocular lens (IOL), various antibiotic-loaded IOLs have been proposed and widely studied to inhibit bacterial infection. However, most of these developed antibiotic-loaded IOLs still suffer from shortcomings such as insufficient drug loading, short release time, poor biocompatibility, and risk of secondary infection. Herein, we propose a zwitterionic and high-drug loading coating for surface modification of commercial hydrophobic IOL with both antifouling and antibacterial properties to effectively prevent POE. In this strategy, zwitterionic poly(carboxylbetaine-co-dopamine methacrylamide) copolymers (pCBDA) and dopamine (DA) were first robustly co-deposited onto IOL surface via facile mussel-inspired chemistry, resulting in a hydrophilic coating (defined as PCB) without sacrificing the high light transmittance of the native IOL. Subsequently, amikacin (AMK), an amine-rich antibiotic was reversibly conjugated onto the coating through the acid-sensitive Schiff base bonds formed by the reaction between amino and catechol groups, with high-drug payload over ∼35.5 μg per IOL and 30 days of sustained drug release under weak acid environment. Benefiting from the antifouling property of zwitterionic pCBDA copolymers, the intraocularly implanted PCB/AMK-coated IOL could effectively resist the adhesion and proliferation of residual LECs to inhibit the development of posterior capsule opacification (PCO) without affecting the normal ocular tissues, demonstrating excellent in vivo biocompatibility. Moreover, the synergy of zwitterionic pCBDA and conjugated AMK with acidic-dependent release behavior endowed this PCB/AMK-coated IOL strong antibacterial activity against both in vitro biofilm formation and in vivo postoperative Staphylococcus aureus infection, suggesting its promising application in preventing POE.

Recent Advances of Intraocular Lens Materials and Surface Modification in Cataract Surgery

Advances in cataract surgery have increased the demand for intraocular lens (IOL) materials. At present, the progress of IOL materials mainly contains further improving biocompatibility, providing better visual quality and adjustable ability, reducing surgical incision, as well as dealing with complications such as posterior capsular opacification (PCO) and ophthalmitis. The purpose of this review is to describe the research progress of relevant IOL materials classified according to different clinical purposes. The innovation of IOL materials is often based on the common IOL materials on the market, such as silicon and acrylate. Special properties and functions are obtained by adding extra polymers or surface modification. Most of these studies have not yet been commercialized, which requires a large number of clinical trials. But they provide valuable thoughts for the optimization of the IOL function.

Foldable Bulk Anti-adhesive Polyacrylic Intraocular Lens Material Design and Fabrication for Posterior Capsule Opacification Prevention

Posterior capsular opacification (PCO) is a primary complication after phacoemulsification combined with intraocular lens (IOL) implantation, which is attributed to adhesion, proliferation, and migration of residual lens epithelial cells on IOL. Although surface hydrophilic coating is considered to be a powerful way to inhibit PCO incidence after surgery, it requires complex post-production processes, thus limiting their applicability. In comparison, bulk modification is a stable, effective, and facile IOL synthesis method for PCO prevention. Herein, a new anti-adhesive IOL material was designed and successfully synthesized by radical copolymerization of ethylene glycol phenyl ether methacrylate (EGPEMA) and 2-(2-ethoxyethoxy) ethyl acrylate (EA). The physicochemical properties of P(EGPEMA-co-EA) copolymer materials, including chemical structure, mechanical, thermal, surface, and optical properties, were analyzed by using ¹H NMR spectroscopy, FT-IR spectroscopy, tensile test, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water contact angle measurement, and UV-vis spectroscopy. The elongation at break and the modulus of elasticity of the copolymer were tunable through the change of the composition of monomers. Compared to other components, the tensile results showed that P(EGPEMA-co-EA) materials (70% EGPEMA in mass ratio, F7) are suitable for the preparation of foldable intraocular lens with lower elastic modulus and higher elongation at break. TGA and DSC showed that the material has high thermal stability, and the glass transition temperature of F7 material is 16.1 °C. The water contact angle measurement results showed that the introduction of EA improved the hydrophilicity of the material. The percentage of transmittance of all copolymers at 400-800 nm is above 85%. Then, the biocompatibility of the materials was evaluated by in vitro assay and subcutaneous implantation. Both in vitro results and subcutaneous implantation experiments showed that the designed IOL materials exhibited a good anti-adhesion effect and no cytotoxicity. Finally, phacoemulsification and IOL intraocular implantation were performed, and the in vivo results confirmed the good PCO prevention ability as well as the biocompatibility of the new IOL materials.

A bone substitute composed of polymethyl-methacrylate bone cement and Bio-Gene allogeneic bone promotes osteoblast viability, adhesion and differentiation

BACKGROUND

Increasing reports on new cement formulations that address the shortcomings of PMMA bone cements and various active components have been introduced to improve the biological activity of PMMA cement.

OBJECTIVE

Evaluating the biological properties of PMMA cements reinforced with Bio-Gene allogeneic bone.

METHODS

The MC3T3-E1 mouse osteoblast-like cells were utilized to determine the effects of Bio-Gene + PMMA on osteoblast viability, adhesion and differentiation.

RESULTS

The combination of allogeneic bone and PMMA increased the number of adherent live cells compared to both control group and PMMA or Bio-Gene group. Scanning electron microscopy observed that the number of cells adhered to Bio-Gene + PMMA was larger than Bio-Gene and PMMA group. Compared with the control and PMMA or Bio-Gene group, the level of ALP and the number of calcium nodules after osteoinduction was remarkably enhanced in Bio-Gene + PMMA group. Additionally, the combination of Bio-Gene and PMMA induced the protein expression of osteocalcin, osterix and collagen I.

CONCLUSION

The composition of PMMA and allogeneic bone could provide a more beneficial microenvironment for osteoblast proliferation, adhesion and differentiation. PMMA bone cement reinforced with Bio-Gene allogeneic bone may act as a novel bone substitute to improve the biological activity of PMMA cement.

A transparent hydrophilic anti-biofouling coating for intraocular lens materials prepared by "bridging" of the intermediate adhesive layer

The attachment of bio-foulants, including unwanted cells, proteins, and bacteria, to a medical device such as an intraocular lens can lead to implantation failure. Hydrophilic polymers are often used as surface modifiers in the fabrication of anti-biofouling coatings, but a hydrophilic coating can easily become swollen and peel off the substrate. In this study, we chose polymethyl methacrylate (PMMA) as the representative material of intraocular lenses because PMMA has better biocompatibility, a higher refractive index, better optical clarity, lighter weight, more stable performance, and lower cost than other intraocular lens materials. We fabricated polyvinyl alcohol (PVA) coatings with or without a "bridge", that is, an intermediate adhesive layer (AL), to increase the adhesion bonding effect between the anti-biofouling coating and the substrate. The results indicated that the prepared coatings were transparent and noncytotoxic. Moreover, the anti-adhesion properties of the cells and the resistance properties to nonspecific protein adsorption of PMMA modified by both AL and PVA coatings were better and more durable compared with the sample only modified with a physically dipped PVA coating. The coating prepared by AL "bridging" provides a new strategy for the preparation of a transparent hydrophilic anti-biofouling coating suitable for PMMA intraocular lens materials.

Modified POSS nano-structures as novel co-initiator-crosslinker: Synthesis and characterization

OBJECTIVE

To synthesize an amine-modified polyhedral oligomeric silsesquioxane (POSS) nano-structure as a novel co-initiator-crosslinker (co-Ini-Linker) and to determine the effect of the co-Ini-linker on the physical and mechanical behavior of an experimental dental composite.

METHODS

The amine-methacrylate POSS nano-structures (AMA-POSS) were chemically synthesized by anchoring a tertiary amine functionality on the methacrylate POSS (MA-POSS) branches. Three types of AMA-POSS, having different amine branches in their structures, were synthesized through the Aza Michael reaction. The chemical structure of AMA-POSSs were evaluated by¹H-NMR spectroscopy. Afterward, the AMA-POSS was incorporated into a dental resin system composed of Bis-GMA, TEGDMA, and photo-initiator. Three resin systems with different AMA-POSS types were then prepared, and their properties were compared with a resin containing DMAEMA as a conventional co-initiator. The degree of conversion evaluated by FTIR spectroscopy and the shrinkage kinetics of the resins were determined through the bonded-disk technique. The flexural properties of the photopolymerized resins were also investigated. The distribution of nano-structures in the matrix resin was analyzed using EDX analysis.

RESULTS

The modified POSS structure and the number of amine branches were confirmed with¹H-NMR spectroscopy. The resin containing 8 amine branches (P8) showed the same degree of conversion (DC%) as the resin containing DMAEMA (P > 0.05). Decreasing the amine branches in the POSS structure, however, revealed an increasing trend in DC%. The resin containing P8 showed the lowest shrinkage strain. By incorporating AMA-POSS into the resin system, the water sorption significantly decreased (P < 0.05). The flexural strength and modulus increased by adding P3 into the resin system (P < 0.05). EDX Si-map revealed that the co-Ini-linker was well dispersed in the resin matrix.

SIGNIFICANCE

The synthesized novel amine-methacrylate POSS nanostructures not only act as an amine co-initiator but also work as a reinforcing filler and a cross-linking agent.

[Biomechanical study of polymethyl methacrylate bone cement and allogeneic bone for strengthening sheep vertebrae]

Objective

To investigate the feasibility and mechanical properties of polymethyl methacrylate (PMMA) bone cement and allogeneic bone mixture to strengthen sheep vertebrae with osteoporotic compression fracture.

Methods

A total of 75 lumbar vertebrae (L ₁-L ₅) of adult goats was harvested to prepare the osteoporotic vertebral body model by decalcification. The volume of vertebral body and the weight and bone density before and after decalcification were measured. And the failure strength, failure displacement, and stiffness were tested by using a mechanical tester. Then the vertebral compression fracture models were prepared and divided into 3 groups ( n=25). The vertebral bodies were injected with allogeneic bone in group A, PMMA bone cement in group B, and mixture of allogeneic bone and PMMA bone cement in a ratio of 1∶1 in group C. After CT observation of the implant distribution in the vertebral body, the failure strength, failure displacement, and stiffness of the vertebral body were measured again.

Results

There was no significant difference in weight, bone density, and volume of vertebral bodies before decalcification between groups ( P>0.05). After decalcification, there was no significant difference in bone density, decreasing rate, and weight between groups ( P>0.05). There were significant differences in vertebral body weight and bone mineral density between pre- and post-decalcification in 3 groups ( P<0.05). CT showed that the implants in each group were evenly distributed in the vertebral body with no leakage. Before fracture, the differences in vertebral body failure strength, failure displacement, and stiffness between groups were not significant ( P>0.05). After augmentation, the failure displacement of group A was significantly greater than that of groups B and C, and the failure strength and stiffness were less than those of groups B and C, the failure displacement of group C was greater than that of group B, and the failure strength and stiffness were less than those of group B, the differences between groups were significant ( P<0.05). Except for the failure strength of group A ( P>0.05), the differences in the failure strength, failure displacement, and stiffness before fracture and after augmentation in the other groups were significant ( P<0.05).

Conclusion

The mixture of allogeneic bone and PMMA bone cement in a ratio of 1∶1 can improve the strength of the vertebral body of sheep osteoporotic compression fractures and restore the initial stiffness of the vertebral body. It has good mechanical properties and can be used as one of the filling materials in percutaneous vertebroplasty.

Comparison of posterior capsule opacification between Clareon CNA0T0 and Tecnis ZCB00 intraocular lenses

INTRODUCTION

The purpose is to compare posterior capsule opacification (PCO) and its impact on vision between Clareon CNA0T0 (Alcon) and Tecnis ZCB00 intraocular lenses (IOLs) (Johnson&Johnson) 1, 6, and 12 months after implantation.

METHODS

A prospective observational study was performed at the Nuestra Señora de Gracia Hospital (Zaragoza, Spain). Fifty eyes (50 patients) with Tecnis IOL (group 1) and 60 eyes (60 patients) with Clareon IOL (group 2) were enrolled. One, 6, and 12 months after age-related cataract surgery by five different surgeons, the following tests were performed: mesopic corrected distance visual acuity (CDVA), CSV1000-E test, KR-1W wavefront analyzer, OQAS II, Catquest-9SF questionnaire and mydriatic slit-lamp pictures. PCO intensity was quantified and the area of opacification was measured using ImageJ (NIH).

RESULTS

Mean age was 71.20 ± 6.79 years in group 1, and 71.73 ± 8.17 years in group 2 (p = 0.72); mean axial length was 23.46 ± 1.14 and 23.53 ± 0.91 mm, respectively (p = 0.72); mean IOL power was 21.69 ± 2.26 D and 21.28 ± 2.44 D, respectively (p = 0.37). One month after surgery there were differences in intensity of PCO (0.73 ± 0.60 and 1.05 ± 0.71, respectively, p = 0.02). Six months after surgery statistical differences were found in VA with 20% CS in mydriatic conditions (0.26 ± 0.21 logMAR (20/36) and 0.18 ± 0.17 logMAR (20/30), respectively, p = 0.04). Twelve months after surgery, no differences were detected between groups. As for the evolution of PCO within the Clareon group, high order aberrations (p < 0.05) and the Strehl ratio (p = 0.02) decreased.

CONCLUSION

There are no differences in slit-lamp pictures or visual function between both IOLs during the first 12 months after implantation.

Surface Modification of Intraocular Lens with Hydrophilic Poly(Sulfobetaine Methacrylate) Brush for Posterior Capsular Opacification Prevention

Purpose: The intraocular lens (IOL) is a common, yet important, implantable device used in treatment of cataract in clinics. However, the unexpected adhesion of postoperative residual lens epithelial cells (LECs) often causes serious complications, such as posterior capsular opacification (PCO), which lead to vision loss again. In this investigation, a poly(sulfobetaine methacrylate) (PSBMA) brush coating was fabricated on an IOL to generate a hydrophilic surface coating on the IOL for enhanced cell adhesion resistance so as to decrease PCO incidence. Methods: The PSBMA brush coating on the IOL surface was fabricated using surface-initiated reversible addition-fragmentation chain transfer polymerization. X-ray photoelectron spectroscopy (XPS) was used to demonstrate the surface coating preparation. The water contact angle (WCA) measurement was used to test surface hydrophilicity. In vitro LEC culture was use to evaluate the cell behavior on the IOL material surfaces, with or without PSBMA coating modification. Finally, animal cataract surgeries were carried out to evaluate in vivo biocompatibilities and anti-PCO effects. Results: The XPS and WCA measurements illustrate successful surface modification and good surface hydrophilicity. The in vitro cell culture results show that the hydrophilic PSBMA polymer brush coating evidently decreases adhesion and proliferation of LECs. Results of the in vivo cataract surgery with intraocular implantation show that PSBMA modification on the IOL surface does not induce side effects in nearby tissues, whereas posterior capsular hyperplasia can be evidently reduced. Conclusion: The PSBMA brush surface-modified IOL has good in vivo biocompatibility and it can effectively reduce the incidence of postoperative PCO.

Synergistic Chemotherapy and Photodynamic Therapy of Endophthalmitis Mediated by Zeolitic Imidazolate Framework-Based Drug Delivery Systems

Endophthalmitis, derived from the infections of pathogens, is a common complication during the use of ophthalmology-related biomaterials and after ophthalmic surgery. Herein, aiming at efficient photodynamic therapy (PDT) of bacterial infections and biofilm eradication of endophthalmitis, a pH-responsive zeolitic imidazolate framework-8-polyacrylic acid (ZIF-8-PAA) material is constructed for bacterial infection-targeted delivery of ammonium methylbenzene blue (MB), a broad-spectrum photosensitizer antibacterial agent. Polyacrylic acid (PAA) is incorporated into the system to achieve higher pH responsiveness and better drug loading capacity. MB-loaded ZIF-8-PAA nanoparticles are modified with AgNO₃ /dopamine for in situ reduction of AgNO₃ to silver nanoparticles (AgNPs), followed by a secondary modification with vancomycin/NH₂ -polyethylene glycol (Van/NH₂ -PEG), leading to the formation of a composite nanomaterial, ZIF-8-PAA-MB@AgNPs@Van-PEG. Dynamic light scattering, transmission electron microscopy, and UV-vis spectral analysis are used to explore the nanoparticles synthesis, drug loading and release, and related material properties. In terms of biological performance, in vitro antibacterial studies against three kinds of bacteria, i.e., Escherichia coli, Staphylococcus aureus, and methicillin-resistant S. aureus, suggest an obvious superiority of PDT/AgNPs to any single strategy. Both in vitro retinal pigment epithelium cellular biocompatibility experiments and in vivo mice endophthalmitis models verify the biocompatibility and antibacterial function of the composite nanomaterials.

Design of smart targeted and responsive drug delivery systems with enhanced antibacterial properties

The use of antibiotics has been an epoch-making invention in the past few decades for the treatment of infectious diseases. However, the intravenous injection of antibiotics lacking responsiveness and targeting properties has led to low drug utilization and high cytotoxicity. More importantly, it has also caused the development and spread of drug-resistant bacteria due to repeated medication and increased dosage. The differences in the microenvironments of the bacterial infection sites and normal tissues, such as lower pH, high expression of some special enzymes, hydrogen peroxide and released toxins, etc., are usually used for targeted and controlled drug delivery. In addition, bacterial surface charges, antigens and the surface structures of bacterial cell walls are all different from normal tissue cells. Based on the special bacterial infection microenvironments and bacteria surface properties, a series of drug delivery systems has been constructed for highly efficient drug release. This review summarizes the recent progress in targeted and responsive drug delivery systems for enhanced antibacterial properties.

Surface Modification of Intraocular Lenses

Objective:

This paper aimed to review the current literature on the surface modification of intraocular lenses (IOLs).

Data Sources:

All articles about surface modification of IOLs published up to 2015 were identified through a literature search on both PubMed and ScienceDirect.

Study Selection:

The articles on the surface modification of IOLs were included, but those on design modification and surface coating were excluded.

Results:

Technology of surface modification included plasma, ion beam, layer-by-layer self-assembly, ultraviolet radiation, and ozone. The main molecules introduced into IOLs surface were poly (ethylene glycol), polyhedral oligomeric silsesquioxane, 2-methacryloyloxyethyl phosphorylcholine, TiO₂, heparin, F-heparin, titanium, titanium nitride, vinyl pyrrolidone, and inhibitors of cytokines. The surface modification either resulted in a more hydrophobic lens, a more hydrophilic lens, or a lens with a hydrophilic anterior and hydrophobic posterior surface. Advances in research regarding surface modification of IOLs had led to a better biocompatibility in both in vitro and animal experiments.

Conclusion:

The surface modification is an efficient, convenient, economic and promising method to improve the biocompatibility of IOLs.

Bottom-up fabrication of zwitterionic polymer brushes on intraocular lens for improved biocompatibility

Intraocular lens (IOL) is an efficient implantable device commonly used for treating cataracts. However, bioadhesion of bacteria or residual lens epithelial cells on the IOL surface after surgery causes postoperative complications, such as endophthalmitis or posterior capsular opacification, and leads to loss of sight again. In the present study, zwitterionic polymer brushes were fabricated on the IOL surface via bottom-up grafting procedure. The attenuated total reflection-Fourier transform infrared and contact angle measurements indicated successful surface modification, as well as excellent hydrophilicity. The coating of hydrophilic zwitterionic polymer effectively decreased the bioadhesion of lens epithelial cells or bacteria. In vivo intraocular implantation results showed good in vivo biocompatibility of zwitterionic IOL and its effectiveness against postoperative complications.

Orthopedic application of spikenard herbal rhizome decorated microstructured polymer biocomposites and their in vitro cytotoxicity

The present study explores the synthesis of highly potential polymer biocomposite from Nardostachys jatamansi rhizome extract. The polymer biocomposites were synthesized from methyl methacrylate by free radical polymerization. ATR-IR enunciate the functional groups attributed at 956 cm-1 (aromatic), a peak appeared at 1685 cm-1 (-C[bond, double bond]O), 1186 cm-1 (-O-CH3), 1149 cm-1 (-C-O-C) framework and 1279 cm-1 (-C-O), which are good agreement for the formation composites. The quantitative evaluations of antimicrobial studies were analyzed by serial dilution method and also improved activity in orthopedic infection pathogens. Cytocompatibility was analyzed by keratinocyte cell lines and it may be used for various biomedical applications.

Surface PEGylation of intraocular lens for PCO prevention: An in vivo evaluation

Posterior capsular opacification (PCO) is a common complication in cataract surgery. The development of PCO is attributed to the combination of adhesion, migration, proliferation, and transdifferentiation of the residual lens epithelial cells (LEC) onto the interface of intraocular lens (IOL) material and lens posterior, in which the initial adhesion is the beginning step and plays important roles. In the present study, hydrophilic polyethylene glycol (PEG) was immobilized onto IOL surface via plasma-aided chemical grafting procedure. The attenuated total reflection - Fourier transform infrared (ATR-FTIR) and contact angle (CA) - measurements indicate the successful surface PEGylation, as well as the excellent hydrophilicity of the surfaces. Compared with pristine IOL, the PEGylation does not influent its optical property, whereas the initial adhesion of LEC is greatly inhibited. In vivo ocular implantation results show that the PEGylated IOL presents good in vivo biocompatibility, and can effectively prevent the PCO development.

Development of Biodegradable Poly(citrate)-Polyhedral Oligomeric Silsesquioxanes Hybrid Elastomers with High Mechanical Properties and Osteogenic Differentiation Activity

Biodegradable elastomeric biomaterials have attracted much attention in tissue engineering due to their biomimetic viscoelastic behavior and biocompatibility. However, the low mechanical stability at hydrated state, fast biodegradation in vivo, and poor osteogenic activity greatly limited bioelastomers applications in bone tissue regeneration. Herein, we develop a series of poly(octanediol citrate)-polyhedral oligomeric silsesquioxanes (POC-POSS) hybrids with highly tunable elastomeric behavior (hydrated state) and biodegradation and osteoblasts biocompatibility through a facile one-pot thermal polymerization strategy. POC-POSS hybrids show significantly improved stiffness and ductility in either dry or hydrated conditions, as well as good antibiodegradation ability (20-50% weight loss in 3 months). POC-POSS hybrids exhibit significantly enhanced osteogenic differentiation through upregulating alkaline phosphatase (ALP) activity, calcium deposition, and expression of osteogenic markers (ALPL, BGLAP, and Runx2). The high mechanical stability at hydrated state and enhanced osteogenic activity make POC-POSS hybrid elastomers promising as scaffolds and nanoscale vehicles for bone tissue regeneration and drug delivery. This study may also provide a new strategy (controlling the stiffness under hydrated condition) to design advanced hybrid biomaterials with high mechanical properties under physiological condition for tissue regeneration applications.

Aggregation induced emission controlled by a temperature-sensitive organic–inorganic hybrid polymer with a particular LCST

The fluorescence intensity change of TPE encapsulated in POSS–PNIPAM with a particular LCST (37.5 °C) with the temperature change.

Comparison of pseudophakic retinal straylight in spherical/aspherical and hydrophobic/hydrophilic intraocular lens

AIM

To study the potential reasons of increased straylight in pseudophakic eyes.

METHODS

Cross-sectional study. Seventy patients diagnosed as bilateral age-related cataract and implanted with Tecnis ZA9003, Sensar AR40e, SA60AT, XLSTABI ZO or Akeros AO intraocular lens (IOL) were enrolled in this research. Straylight was measured by a C-Quant straylight meter three to four weeks postoperatively. Five different modalities of IOL, including spherical/aspherical optics and hydrophobic/hydrophilic material were tested in this study. Normal as well as dilated pupils were used. The main outcome variable for straylight measurement was the logarithmic straylight parameter, log(s).

RESULTS

The straylight parameter increased significantly after pupil dilation (P<0.05). Straylight of aspherical IOL was significantly higher after pupil dilation (P<0.05) compared to spherical IOL. In normal pupil, straylight of hydrophobic IOL was significant higher when compared with hydrophilic IOL (P<0.05).

CONCLUSION

Straylight and visual acuity stand for the different aspects of visual function. Several factors including pupil diameter, optic material, aspherical design of IOL influence intraocular light scattering in pseudophakic eyes. Further investigation was needed to study the impact of optic material and optic surface design on pseudophakic straylight.

Low-temperature polymerization of methyl methacrylate emulsion gels through surfactant catalysis

Poly(methyl methacrylate) (PMMA)/silica/cetyltrimethylammonium bromide (CTAB) composites were prepared through surfactant catalyzed free radical polymerizations at 40 °C. Fumed silica particles controlled the morphology of the polymeric composites producing porous structures. The internal structures of the porous composite were determined using temperature-modulated differential scanning calorimetry (TMDSC). The fumed silica particles were encapsulated by an incompletely covered CTAB monolayer, with a crystallization temperature, T(C,CTAB)=76 °C, and a mixed PMMA/CTAB shell, with T(C,CTAB)=63 °C. The fumed silica surfaces acted as inhibitors for PMMA free radical polymerizations. Much of the PMMA formed in the composites was adsorbed on the silica, as evidenced by its elevated glass transition temperature compared to bulk. The enhanced decomposition of the initiator was catalyzed by CTAB and resulted in free radical polymerization of PMMA at 40 °C, which is considerably lower than the temperatures normally used for PMMA synthesis by free radical means with thermal initiation. These lowered polymerization temperatures allow energy efficient production of composites, which can incorporate temperature sensitive materials.

Biomolecular functionalization for enhanced cell-material interactions of poly(methyl methacrylate) surfaces

The integration of implants or medical devices into the body tissues requires of good cell-material interactions. However, most polymeric materials used for these applications lack on biological cues, which enhanced mid- and long-term implant failure due to weak integration with the surrounding tissue. Commonly used strategies for tissue-material integration focus on functionalization of the material surface by means of natural proteins or short peptides. However, the use of these biomolecules involves major drawbacks such as immunogenic problems and oversimplification of the constructs. Here, designed elastin-like recombinamers (ELRs) are used to enhance poly(methyl methacrylate) surface properties and compared against the use of short peptides. In this study, cell response has been analysed for different functionalization conditions in the presence and absence of a competing protein, which interferes on surface-cell interaction by unspecific adsorption on the interface. The study has shown that ELRs can induce higher rates of cell attachment and stronger cell anchorages than short peptides, being a better choice for surface functionalization.

Surface modification of intraocular lenses with hyaluronic acid and lysozyme for the prevention of endophthalmitis and posterior capsule opacification

Posterior capsule opacification is one of the complications of cataract surgery caused by the adhesion and reproduction of residual human lens epithelial cells (HLECs) on the posterior capsule.

Ocular biocompatibility evaluation of POSS nanomaterials for biomedical material applications

The ocular biocompatibility of polyhedral oligomeric silsesquioxanes (POSSs) was systematically evaluated for ocular biomedical device applications.

Hydrated polysaccharide multilayer as an intraocular lens surface coating for biocompatibility improvements

A swollen polysaccharide multilayer was coated on an IOL to inhibit LEC adhesion and proliferation, thus decreasing PCO incidence after implantation.