Glycopolymers as a Tool for Specific Surface Modification of Polymeric Biomaterials

Surfaces play an important role in a biological system for most biological reactions occurring at surfaces and interfaces. The development of biomaterials for tissue engineering is to create perfect surfaces which can provoke specific cellular responses and direct new tissue regeneration. The improvement in biocompatibility of biomaterials for tissue engineering by directed surface modification is an important contribution to biomaterials development. Among many biomaterials used for tissue engineering, polyesters have been well documented for their excellent biodegradability, biocompatibility and nontoxicity. However, poor hydrophilicity and the lack of natural recognition sites on the surface of polyesters have greatly limited their further application in the tissue engineering field. Therefore, how to introduce functional groups or molecules to polyester surfaces, which ideally adjust cell/tissue biological functions, becomes more and more important. In this review, recent advances in polyester surface modification and their applications are reviewed. The development of new technologies or methods used to modify polyester surfaces for developing their biocompatibility is introduced. The results of polyester surface modifications by surface morphological modification, surface chemical group/charge modification, surface biomacromolecule modification and so on are reported in detail. Modified surface properties of polyesters directly related to in vitro/vivo biological performances are presented as well, such as protein adsorption, cell attachment and growth and tissue response. Lastly, the prospect of polyester surface modification is discussed, especially the current conception of biomimetic and molecular recognition.

Solid-binding peptides (SBPs) are a powerful tool for surface modification of metallic biomaterials which improve the biocompatibility and functionality of medical devices. This review provides a comprehensive overview of SBP technology for metallic biomaterials. We begin with a focus on phage display technology, the cornerstone method for selecting and developing SBPs. The application of SBPs to major metallic biomaterials, including titanium, stainless steel, and cobalt–chromium alloys, is then extensively discussed with specific examples and outcomes. We also address the advantages of SBPs compared to traditional surface modification methods, such as their high specificity and biocompatibility. Furthermore, this review explores current challenges in the field, such as the integration of computational approaches for rational SBP design. To create multifunctional surfaces, the combination of SBPs with other advanced technologies is also considered. This review aims to provide a thorough understanding of the current state and future potential of SBP technology in enhancing metallic biomaterials for medical application.

Micropatterned silica thin films with nanohydroxyapatite micro-aggregates for guided tissue regeneration

The science related to biomaterials and tissue engineering accounts for a growing part of our knowledge. Surface modifications of biomaterials, their performance in vitro, and the interaction between them and surrounding tissues are gaining more and more attention. It is because we are interested in finding sophisticated materials that help us to treat or mitigate different disorders. Therefore, efficient methods for surface analysis are needed. Several methods are routinely applied to characterize the physical and chemical properties of the biomaterial surface. Mass Spectrometry Imaging (MSI) techniques are able to measure the information about molecular composition simultaneously from biomaterial and adjacent tissue. That is why it can answer the questions connected with biomaterial characteristics and their biological influence. Moreover, this kind of analysis does not demand any antibodies or dyes that may influence the studied items. It means that we can correlate surface chemistry with a biological response without any modification that could distort the image. In our review, we presented examples of biomaterials analyzed by MSI techniques to indicate the utility of SIMS, MALDI, and DESI-three major ones in the field of biomaterials applications. Examples include biomaterials used to treat vascular system diseases, bone implants with the effects of implanted material on adjacent tissues, nanofibers and membranes monitored by mass spectrometry-related techniques, analyses of drug-eluting long-acting parenteral (LAPs) implants and microspheres where MSI serves as a quality control system.

This special issue contains selected papers which were presented as invited and contributed communications at the workshop entitled ‘Surface modification and functionalization of materials for biomedical applications’ (BIO-COAT 2010) which was held on 24 June 2010 in Zaragoza (Spain). The surface of a material plays a major role in its interaction with the biological medium. Processes related to the mechanical stability of articular devices in contact, osseointegration, thrombogenicity, corrosion and leaching, or the inflammatory response of rejection of a material, are clearly conditioned by the surface properties. Therefore, the modification or functionalization of surfaces can have an important impact on these issues. New techniques for functionalization by thin film deposition or surface treatments help to improve superficial properties, while understanding the interaction of the surface–biological medium is critical for their application in new devices. Jointly organized by the Spanish Materials Research Society, BIO-COAT 2010 provided an open forum to discuss the progress and latest developments in thin film processing and the engineering of biomaterials. Invited lectures were particularly aimed at providing overviews on scientific topics and were given by recognized world-class scientists. Two of them have contributed with a proceedings article to this selected collection (articles 012001 and 012008). The contributed communications were focused on particular cutting-edge aspects of thin film science and functionalization technologies for biomaterials, showing the major scientific push of Spanish research groups in the field. The 2010 BIO-COAT conference was organized along four main topics: (1) functionalization and texture on surfaces, (2) tribology and corrosion, (3) the surface modification of biomaterials, and (4) surface–biological environment interactions. The papers published in this volume were accepted for publication after peer-review as are regular papers. The editor of this proceedings volume gratefully acknowledges all referees for their valuable work, sometimes working to quite short deadlines. Finally, BIO-COAT 2010 would not have been successful without the strong involvement and input of the local organizing committee in Zaragoza, and the support of the University of Zaragoza. We sincerely thank them all for their efforts. Jose L Endrino (Editor) Jose A Puértolas (Chairman) Jose M Albella (Chairman)

The synthesis of dye-labeled poly(methacrylic acid) (PMAA) grafted silica nanoparticles was studied. Surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization of tert-butylmethacrylate (tBuMA) was conducted on dye-labeled CPDB coated silica nanoparticles followed by sequential removal of the thiocarbonylthio end groups and the tert-butyl moieties. Additionally, as a more straightforward strategy, direct polymerization of methacrylic acid on silica nanoparticles with a diameter size as small as 15 nm was conducted via the RAFT polymerization technique. A variety of PMAA brushes with different lengths and densities were prepared on nanoparticle surfaces via surface-initiated RAFT polymerization with excellent control and surface grafting densities as high as 0.65 chains/nm2. The grafted PMAA was methylated by trimethylsilyldiazomethane to conduct organic phase GPC characterization. The dye-labeled PMAA grafted nanoparticles provide a platform to bind biomolecules and to track the movement of the nanoparticles in biological systems.

Structurally tailored and engineered macromolecular (STEM) networks are attractive materials for soft robotics, stretchable electronics, tissue engineering, and 3D printing due to their tunable properties. To date, STEM networks have been synthesized by atom transfer radical polymerization (ATRP) or the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization and ATRP. RAFT polymerization could have limited selectivity with ATRP inimer sites that can participate in radical-transfer processes. On the other hand, living ring-opening metathesis polymerization (ROMP) can produce a polymeric network with latent ATRP initiator sites in high selectivity. Herein, for the first time, we report the syntheses of STEM zero-generation (STEM-0) networks using a monomer, a cross-linker, and an ATRP/ROMP inimer via living ROMP, followed by their modification using a second monomer via ATRP to synthesize STEM first-generation (STEM-1) networks. The mechanical property and swelling capacity analyses of these networks were carried out. A change in mechanical properties and swelling capacity of these networks was observed due to their structural modification.

Surface modification of polymers by plasma treatments for the enhancement of biocompatibility and controlled drug release

Surface modification and property analysis of biomedical polymers used for tissue engineering

Zinc oxide nanoparticles (ZnO NPs) are one of the most widely used nanomaterials. The ZnO NPs are currently used in chemical, cosmetic, pharmaceutical and electronic products resulting in increased human exposure. Following oral exposure, these NPs can accumulate in various organs and induce toxicity due to their physiochemical characteristics. Nevertheless, limited safety information is available, especially in terms of their interactions with various binding proteins leading to potential toxic effects. Principally, particles administered orally encounter diverse biological matrices, such as gastrointestinal (GI) fluids and blood, and these interactions lead to the formation of particle–biomatrix corona of different affinity. This can alter their physicochemical property, biological interaction and biological fate. The formed protein corona around the NPs enriched with opsonin protein is recognized by macrophages and immune effectors cells, resulting in rapid clearance with induced toxicity. Hence, the potential ZnO NPs toxicity pathway and their exact biological consequences in respect to their variation in surface property needed the understanding of their potential mechanisms in vivo model system and their protective effect by surface modification may provide mechanistic outputs during drug delivery system as well as in scope of nanomedicine.

Surface design of biodegradable magnesium alloys — A review

Contact lenses are one of the most successful materials. They are used by over 125 million people around the world. This review gives an description on history, properties and modifications of contact lens materials. Starting from a piece of glass to current silicone hydrogel lenses, contact lens material development has witnessed a huge step. Properties of typical contact lens materials are introduced, including mechanical properties, equilibrium water content, oxygen permeability, and surface properties. Tensile stress is mentioned as a significant mechanical property, whereas wettability and friction are discussed in surface properties. Corresponding modifications to increase wearing comfort are also discussed in this review, such as copolymerization, cross-linking and surface modification. These methods are applied to materials typically silicone hydrogels to increase water content and oxygen permeability or to optimize the mechanical and surface properties. Nowadays, contact lenses in the market provide users with longer wearing time and more comfortable wearing experiences.

Materials intended for use as implantable or diagnostic devices are required not only to display the required functional bulk properties but also have surface properties that elicit a desired biological response, and do so with high selectivity. The area of surface functionalization approaches and bioactive coatings for biomaterials and biomedical devices has been the subject of much research over several decades; yet, many challenges still remain to be solved. The 5th International Symposium on Surface and Interface of Biomaterials (ISSIB) held in Sydney (Australia) in April 2015 was an ideal forum to discuss the most recent developments in biomaterial surface modification, characterization, and evaluation of biological responses. The conference covered a range of topics including antimicrobial coatings, analysis of biomaterial surfaces and interfaces, biomolecules and cells at surfaces and interfaces, nanoparticles, functional coatings, patterned biomaterials, nanofabrication, bioreactors, and biosensors. In this special conference issue, the authors include papers that detail some of the highlights from the meeting.

Event Abstract Back to Event The atomic ordering and its correlation to protein adsorption on biocompatible metal oxide coatings Phaedra Silva-Bermudez1, 2, Margarita Rivera3 and Sandra E. Rodil2 1 Instituto Nacional de Rehabilitación, Tissue Engineering, Cell Therapy and Regenerative Medicine Unit, Mexico 2 Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales, Mexico 3 Universidad nacional Autónoma de México, Instittuto de Física, Mexico Introduction: Biomaterials that can, simultaneously, direct an adequate biological response and meet biomechanical requirements are essential for dental implants. Coatings are interesting options to tailor the surface properties of mechanically-adequate bulk materials and, consequently, their biological response. Correlations between biological response and surface properties such as roughness (Ra), chemistry or wettability have been widely studied; however, the atomic ordering (AO) and surface free energy (SFE) effects are less understood[1],[2]. The use of amorphous (a-) and crystalline (c-) coatings can confer novel nanotopographies or SFE to materials and constitute controlled models to study the biological effects of specific surface properties; e.g. it is possible to modify the Ra or the wettability while keeping the surface chemistry. One of the first events occurring upon material-biological media interaction is protein adsorption, which influences the development of cell-surface interactions. Thus, in this study, c- and a- ZrO2 and TiO2 coatings, biocompatible oxides of interest for dental implants, were used to study the correlations among atomic ordering, surface properties and protein adsorption. Bovine Serum Albumin (BSA) was used as model protein. Materials and Methods: a- and c- ZrO2 and TiO2 thin films were deposited on Si substrates by Reactive Magnetron Sputtering in Ar/O2 atmosphere, from Zr or Ti targets. Substrates were heated to 250°C or 300°C during deposition to obtain c-ZrO2 and c-TiO2, respectively. Coatings surface properties (AO, wettability, SFE, Ra and chemical composition) were characterized by X-ray Diffraction, Contact Angle, Atomic Force Microscopy, Profilometry, Ellipsometry (ELP) and X-ray Photoelectron Spectroscopy (XPS). Coatings samples were immersed in BSA solutions and a set of ELP angles was acquired in-situ every 2 s at 3 eV for 2400 s. At equilibrium, ELP spectra (1.5-4.2 eV) were acquired and fitted to a four phase optical model to obtain the adsorbed BSA surface mass concentration. Then, samples were rinsed, dried in N2 and analyzed by XPS to quantify the adsorbed protein through analysis of C 1s and N 1s energy regions. Statistical significance was examined by ANOVA with Bonferroni’s modification. Results and Discussion: Coating roughness and water contact angle (WCA) increased with atomic ordering; more notoriously for a-TiO2 and c-TiO2. Different morphologies were observed for c- and a- coatings. Coatings had similar SFE; mainly dispersive with a small polar contribution (γAB). The highest and the smallest γAB were observed for a-TiO2 and a-ZrO2, respectively. γAB was mainly basic (γ_) for all coatings but c-TiO2 with γAB of acidic nature (γ+). A higher BSA adsorption was observed on c- oxides than on their corresponding a- oxides. BSA adsorption was higher on ZrO2 than on TiO2, independently of the atomic ordering. Conclusions: The higher BSA adsorption on c- coatings, compared to the a- ones, seems to be chemistry-related: on TiO2, it may be, mainly, due to an increment of electrostatic interactions between BSA and c-TiO2; γ+ for c-TiO2 > γ+ for a-TiO2. On ZrO2, it may be due to the higher available surface area (Ra) on c-ZrO2 than on a-ZrO2. Coadsorption of H2O and BSA molecules on TiO2 may explain the smaller BSA adsorption on TiO2 than on ZrO2, independently of the atomic ordering. This presents the possibility to tailor specific molecules/ions adsorption through modifying the coatings atomic ordering. Acknowledgements to the financial funding from CONACYT under the research Grant CONACyT-CB-152995 and from DGAPA under the research Grants DGAPA-PAPIIT-IG100113, DGAPA-PAPIIT-IN118814 and DGAPA-PAPIIT-IN118914

The majority of currently used implant materials in orthopaedics lacks osteoconductivity. This paper reviews our efforts of using a number of surface modification techniques (hydrothermal-electrochemical deposition, plasma spraying, spraying-and-sintering, ion beam assisted deposition, and biomimetic deposition) to improve the osteoconductivity of metallic, polymeric and ceramic biomaterials. Furthermore, biomimetic processes have been employed to render non-bioactive polymer tissue engineering scaffolds osteoconductive. Surface modification has an important role to play in the development of materials for human tissue repair and regeneration.