Surface Modification Of Biomaterials Research Articles

Novel Application of Diffuse Coplanar Surface Barrier Discharge: Fast, Efficient and Controlled Surface Functionalization

Plasma chemistry is currently an interesting approach to surface modification of materials. In general plasma treatment is a fast process, affecting only the units of nanometers of the surface layer without altering the bulk properties. and has many potential benefits such as minimal waste and control of surface functionality. It represents a dry and environmentally friendly process that can achieve comparable results to wet chemical treatment. The research and development of plasma sources, mainly operating at atmospheric pressure, has been the main activity of the centre CEPLANT, Brno, Czech Republic for several decades. Our development is generally aimed at fast, efficient, and low-cost plasma treatments, easily implementable in industry, and flexibly responds to industrial requirements and current trends.One of our most versatile plasma source, the so-called Diffuse Coplanar Surface Barrier Discharge (DCSBD) has been developed for in-line surface modification of various materials, primarily for fabric materials. DCSBD produces a 0.3 mm thin layer of non-equilibrium, cold macroscopically diffuse plasma at atmospheric pressure (Fig. 1) in any working gas, including oxygen, hydrogen, or even water vapors. Due to its strongly non-equilibrium nature, operation at atmospheric pressure, and low temperatures, the DCSBD represents a unique plasma source suitable for surface modification of low-cost and temperature-sensitive materials [1-4].Unique results have been achieved in research on the practical application of flexible conductive layers on glass, with a focus on the deposition of transparent organic polymer coatings on ultra-thin flexible glass (UTFG). We have developed and optimized efficient and fast dry non-contact cleaning and activation of fragile and lightweight conductive glasses using DCSBD. The high-speed plasma treatment corresponding to the exposure times in the order of units of seconds leads to a synergistic balance between the efficient removal of impurities (carbohydrates) adsorbed on the UTFG surface and the formation of oxygen-based functional groups. Subsequent PEDOT:PSS-based coatings sprayed on plasma-treated UTFG surfaces achieve significantly higher electrical conductivity compared to the standard liquid-purified samples. This method combined with the unique properties of UTFG provides prospective results applicable in microelectronics, and optoelectronic devices like sensors or displays.In the field of composite materials research, we have discovered that plasma treatment of reinforcing fibers leads to improvement of the mechanical properties of laminated fiber-reinforced polymer (FRP) composites. Efficient functionalization of various commonly used reinforcement fibers (flax, aramid and glass) in atmospheric low-temperature DCSBD increases the interfacial adhesion at the fiber-matrix interface, which has a provable positive effect on the resulting mechanical properties.DCSBD plasma can also be utilized for the initiation of reducing chemical reactions. We have developed a simple and fast chemical-free fabrication method of 2D and 3D reduced graphene oxide (rGO) structures using an electrical plasma-triggered reduction & exfoliation of 3D porous graphene oxide (GO) aerogel-like materials [4] and also 2D GO paper-like films starting at temperatures not higher than 100 oC [5]. The plasma triggered the self-propagating reduction & exfoliation fast modification of GO into rGO, while the rGO structures retained their original shape without abrupt disintegration. We observed an approximately 105 fold decrease of the rGO paper resistivity compared to the unmodified GO paper. This novel method opens new opportunities for the production of conductive rGO and rGO-based composites for modern industrial applications.Innovative results were achieved in the fabrication of ZnO nanofibers by a novel calcination approach assisted by DCSBD. Exposition of the polyvinyl pyrrolidone/zinc acetate fibers to DCSBD before the thermal processing leads to the gentle low-temperature removal of organic material. Plasma pre-treated nanofibers are characterized by a smaller diameter and retain a defined fibrous structure during heat treatment. Moreover, the ZnO nanofibers prepared by a combination of plasma and heat treatment exhibited considerably higher photodegradation activity increasing with decreasing calcination temperature [6]. The low-temperature and high oxidation potential of plasma makes plasma-assisted calcination of the inorganic nanofibers an attractive alternative to conventional thermal annealing with potential application in optoelectronics or biosensors.The mentioned applications are only a small fragment of available cases of utilization of the DCSBD, which is now commonly established and applied in the field of surface modification of various materials (glass, metals, non-woven fabrics, polymers, paper, nanofibres) and biomaterials (seeds, grains, wood, natural leather).[1] M. Černák et al., Plasma Physics and Controlled Fusion 53 (2011) 1-8[2] R. Talviste et al., Surface and Interface 16 (2019) 2468-0230[3] T. Morávek et al., Open Chemistry 13 (2015) 236-244[4] R. Krumpolec et al., Flatchem 35 (2022)[5] F. Zelenák , Carbon N. Y. 215 (2023) 118436[6] V. Medvecká et al., Applied Surface Science, 581 (2022) 152384 Figure 1

Investigation of alterations in the physical properties of plasma treated PVA/Aloe Vera nanofiber mats for potential biomedical applications

Atmospheric dielectric barrier (A-DBD) holds promise in biomaterial surface modification, due to its tailoring ability of tuning chemical/physical properties of material surface at ambient conditions. Thus, this work reports A-DBD plasma treatment for the electrospun PVA/Aloe Vera nanofiber mat to probe changes in mechanical properties and plasma induced surface properties. FE-SEM confirmed bead-free nanofibers with average diameter of 134 nm. The tensile strength and Young’s modulus get an improvement of 27.14 % and 57.71 %, respectively for the plasma treated PVA/AV nanofiber. Further, the plasma treated PVA/AV nanofiber mat shows improved surface wettability with a decrease in contact angle. These findings suggest promising potential for biomedical applications.

Silanization Strategies for Tailoring Peptide Functionalization on Silicon Surfaces: Implications for Enhancing Stem Cell Adhesion.

Biomaterial surface engineering and the integration of cell-adhesive ligands are crucial in biological research and biotechnological applications. The interplay between cells and their microenvironment, influenced by chemical and physical cues, impacts cellular behavior. Surface modification of biomaterials profoundly affects cellular responses, especially at the cell-surface interface. This work focuses on enhancing cellular activities through material manipulation, emphasizing silanization for further functionalization with bioactive molecules such as RGD peptides to improve cell adhesion. The grafting of three distinct silanes onto silicon wafers using both spin coating and immersion methods was investigated. This study sheds light on the effects of different alkyl chain lengths and protecting groups on cellular behavior, providing valuable insights into optimizing silane-based self-assembled monolayers (SAMs) before peptide or protein grafting for the first time. Specifically, it challenges the common use of APTES molecules in this context. These findings advance our understanding of surface modification strategies, paving the way for tailoring biomaterial surfaces to modulate the cellular behavior for diverse biotechnological applications.

Surface modification of medical grade biomaterials by using a low-temperature-processed dual functional Ag-TiO2 coating for preventing biofilm formation.

Biofilm development in medical devices is considered the major virulence component that leads to increased mortality and morbidity among patients. Removing a biofilm once formed is challenging and frequently results in persistent infections. Many current antibiofilm coating strategies involve harsh conditions causing damage to the surface of the medical devices. To address the issue of bacterial attachment in medical devices, we propose a novel antibacterial surface modification approach. In this paper, we developed a novel low-temperature based solution-processed approach to deposit silver nanoparticles (Ag NPs) inside a titanium oxide (TiO2) matrix to obtain a Ag-TiO2 nanoparticle coating. The low temperature (120 °C)-based UV annealed drop cast method is novel and ensures no surface damage to the medical devices. Various medical-grade biomaterials were then coated using Ag-TiO2 to modify the surface of the materials. Several studies were performed to observe the antibacterial and antibiofilm properties of Ag-TiO2-coated medical devices and biomaterials. Moreover, the Ag-TiO2 NPs did not show any skin irritation in rats and showed biocompatibility in the chicken egg model. This study indicates that Ag-TiO2 coating has promising potential for healthcare applications to combat microbial infection and biofilm formation.

Layer-by-layer assembly of poly-l-lysine/hyaluronic acid protein reservoirs on poly(glycerol sebacate) surfaces

The modification of biomaterial surfaces has become increasingly relevant in the context of ongoing advancements in tissue engineering applications and the development of tissue-mimicking polymer materials. In this study, we investigated the layer-by-layer (LbL) deposition of polyelectrolyte multilayer protein reservoirs consisting of poly-l-lysine (PLL) and hyaluronic acid (HA) on the hydrophobic surface of poly(glycerol sebacate) (PGS) elastomer. Using the methods of isothermal titration calorimetry and surface plasmon resonance, we systematically investigated the interactions between the polyelectrolytes and evaluated the deposition process in real time, providing insight into the phenomena associated with film assembly. PLL/HA LbL films deposited on PGS showed an exceptional ability to incorporate bone morphogenetic protein-2 (BMP-2) compared to other growth factors tested, thus highlighting the potential of PLL/HA LbL films for osteoregenerative applications. The concentration of HA solution used for film assembly did not affect the thickness and topography of the (PLL/HA)10 films, but had a notable impact on the hydrophilicity of the PGS surface and the BMP-2 release kinetics. The release kinetics were successfully described using the Weibull model and hyperbolic tangent function, underscoring the potential of these less frequently used models to compare the protein release from LbL protein reservoirs.

Mass Spectrometry Imaging of Biomaterials.

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.

Research and Application of Metal–Organic Framework in Surface Modification of Biomaterials—A Review

Surface modification is one of the core technologies in the field of biomedical materials. The fundamental purpose is to enable the surface of biomass materials to have better biocompatibility to better meet clinical needs. A metal–organic framework (MOF) is composed of organic links and metal nodes. It is a type of new crystal porous material with important application potential. In recent years, it has been explored in the field of biomass materials. This review introduces the structure and synthesis of MOF and systematically combs, summarizes and evaluates the research and application of MOF in cardiovascular therapy, tumor therapy, bone tissue engineering and other scenarios, in order to provide reference and inspiration for subsequent researchers.

Evading stability-biocompatibility tradeoff in TiNb coatings with armour-like super hydrophilic micro-nano structure surface

Modification of micro-nano structures on the surface of medical implants using a femtosecond laser (FSL) can improve cell behavior, increase tissue and material bonding strength, and promote preferred osseointegration. Nevertheless, the FSL processed micro-nano structures suffer from a compromise between biocompatibility and structural stability. Herein, a Ti32·5Nb alloy laser cladding (LC) coating was initially created on the surface of the Ti6Al4V (TC4) substrate, followed by the construction of an armour-like micro-nano structure with structural stability and biocompatibility on the coating surface. The results show that the microhardness, were resistance and corrosion resistance of the coatings were significantly improved. It efficiently prevents wear damage to the micro-nano structure by modifying the surface armour structure of FSL. In addition, a considerable quantity of hydroxyapatite (HA) is deposited on the surface, resulting in a Ca/P ratio that is closer to that of osteogenesis. Moreover, the surface structure is a periodic micro-nano structure with three-level distribution, which can guide the migration and proliferation of cell nanofiber matrix. Human osteosarcoma cells (MG-63) adhere to the surface and proliferate rapidly along the direction of the micro-nano structure. Hereby, the armoured micro-nano structures developed exhibit sustained wear resistance and great biocompatibility. It offers a wide range of applications in the field of surface modification of orthopedic biomaterials.

Atmospheric Microplasma Treatment Based on Magnetically Controlled Fe–Al Dynamic Platform for Organic and Biomaterials Surface Modification

By exploiting the physical effect of the electron emission from a thermionic source in combination with a magnetically controlled Fe–Al dynamic platform to assist electrical discharge, we generated atmospheric microplasma (AM). The electrical characteristics of microplasma discharge-induced cold atmospheric plasma in combination with a magnetically controlled Fe–Al dynamic platform in open air were evaluated. The surface analysis of organic wheat seeds was investigated at two steps: (1) the coating effect of an Al nanoparticle with an electrons drift toward the seed surface along the direction of an electric field and (2) inelastic collision with secondary electrons moving from the cathode in the presence of an electric field. Using SEM microscopy analysis, it was found that plasma affects seed surface topography and apparent contact angle (ACA). The effect of atmospheric microplasma treatment leads to seed surface modification by the manifestation of fine mesh structures on the seed surface. Well-established AM technology will garner interest in agriculture and biomaterials coatings applications.

Efficient Osteogenic Activity of PEEK Surfaces Achieved by Femtosecond Laser-Hydroxylation.

Poly(etheretherketone) (PEEK) is regarded as an attractive orthopedic material because of its good biocompatibility and mechanical properties similar to natural bone. The efficient activation methods for the surfaces of PEEK matrix materials have become a hot research topic. In this study, a method using a femtosecond laser (FSL) followed by hydroxylation was developed to achieve efficient bioactivity. It produces microstructures, amorphous carbon, and grafted -OH groups on the PEEK surface to enhance hydrophilicity and surface energy. Both experimental and simulation results show that our modification leads to a superior ability to induce apatite deposition on the PEEK surface. The results also demonstrate that efficient grafting of C-OH through FSL-hydroxylation can effectively enhance cell proliferation and osteogenic differentiation compared to other modifications, thus improving osteogenic activity. Overall, FSL hydroxylation treatment is proved to be a simple, efficient, and environmentally friendly modification method for PEEK activation. It could expand the applications of PEEK in orthopedics, as well as promote the surface modification and structural design of other polymeric biomaterials to enhance bioactivity.

Bacterial Biofilm Formation on Biomaterials and Approaches to Its Treatment and Prevention.

Bacterial biofilms can cause widespread infection. In addition to causing urinary tract infections and pulmonary infections in patients with cystic fibrosis, biofilms can help microorganisms adhere to the surfaces of various medical devices, causing biofilm-associated infections on the surfaces of biomaterials such as venous ducts, joint prostheses, mechanical heart valves, and catheters. Biofilms provide a protective barrier for bacteria and provide resistance to antimicrobial agents, which increases the morbidity and mortality of patients. This review summarizes biofilm formation processes and resistance mechanisms, as well as the main features of clinically persistent infections caused by biofilms. Considering the various infections caused by clinical medical devices, we introduce two main methods to prevent and treat biomaterial-related biofilm infection: antibacterial coatings and the surface modification of biomaterials. Antibacterial coatings depend on the covalent immobilization of antimicrobial agents on the coating surface and drug release to prevent and combat infection, while the surface modification of biomaterials affects the adhesion behavior of cells on the surfaces of implants and the subsequent biofilm formation process by altering the physical and chemical properties of the implant material surface. The advantages of each strategy in terms of their antibacterial effect, biocompatibility, limitations, and application prospects are analyzed, providing ideas and research directions for the development of novel biofilm infection strategies related to therapeutic materials.

Orthopaedic applications of cold physical plasma.

Cold physical plasma (CPP) technology is of high promise for various medical applications. The interplay of specific components of physical plasma with living cells, tissues and organs on a structural and functional level is of paramount interest with the aim to induce therapeutic effects in a controlled and replicable fashion. In contrast to other medical disciplines such as dermatology and oromaxillofacial surgery, research reports on CPP application in orthopaedics are scarce. The present implementation of CPP in orthopaedics involves surface modifications of orthopaedic materials and biomaterials to optimize osseointegration. In addition, the influence of CPP on musculoskeletal cells and tissues is a focus of research, including possible adverse reactions and side effects. Its bactericidal aspects make CPP an attractive supplement to current treatment regimens in case of microbial inflammations such as periprosthetic joint infections. Attributed anticancerogenic and pro-apoptotic effects underline the clinical relevance of CPP as an additive in treating malignant bone lesions. The present review outlines ongoing research in orthopaedics involving CPP; it distinguishes considerations for safe application and the need for more evidence-based research to facilitate robust clinical implementation.

Ultraviolet Light-Based Micropattern Printing on Titanium Surfaces to Promote Early Osseointegration.

Patterned interfaces are widely used for surface modification of biomaterials because of a morphological unit similar to that of native tissue. However, engineering fast and cost-effective high-resolution micropatterns directly onto titanium surfaces remains a grand challenge. Herein, a simply designed ultraviolet (UV) light-based micropattern printing to obtain geometrical patterns on implant interfaces is fabricated by utilizing customized photomasks and titanium dioxide (TiO2 ) nanorods as a photo-responsive platform. The technique manipulates the cytoskeleton of micropatterning cells on the surface of TiO2 nanorods. The linear pattern surface shows the elongated morphology and parallel linear arrangements of human mesenchymal stem cells (hMSCs), significantly enhancing their osteogenic differentiation. In addition to the upregulated expression of key osteo-specific function genes in vitro, the accelerated osseointegration between the implant and the host bone is obtained in vivo. Further investigation indicates that the developed linear pattern surface has an outstanding effect on the cytoskeletal system, and finally activates Yes-Associated Protein (YAP)-mediated mechanotransduction pathways, initiating hMSCs osteogenic differentiation. This study not only offers a microfabrication method that can be extended to fabricate various shape- and size-controlled micropatterns on titanium surfaces, but also provides insight into the surface structure design for enhanced bone regeneration.

Antibacterial-Based Hydrogel Coatings and Their Application in the Biomedical Field—A Review

Hydrogels exhibit excellent moldability, biodegradability, biocompatibility, and extracellular matrix-like properties, which make them widely used in biomedical fields. Because of their unique three-dimensional crosslinked hydrophilic networks, hydrogels can encapsulate various materials, such as small molecules, polymers, and particles; this has become a hot research topic in the antibacterial field. The surface modification of biomaterials by using antibacterial hydrogels as coatings contributes to the biomaterial activity and offers wide prospects for development. A variety of surface chemical strategies have been developed to bind hydrogels to the substrate surface stably. We first introduce the preparation method for antibacterial coatings in this review, which includes surface-initiated graft crosslinking polymerization, anchoring the hydrogel coating to the substrate surface, and the LbL self-assembly technique to coat crosslinked hydrogels. Then, we summarize the applications of hydrogel coating in the biomedical antibacterial field. Hydrogel itself has certain antibacterial properties, but the antibacterial effect is not sufficient. In recent research, in order to optimize its antibacterial performance, the following three antibacterial strategies are mainly adopted: bacterial repellent and inhibition, contact surface killing of bacteria, and release of antibacterial agents. We systematically introduce the antibacterial mechanism of each strategy. The review aims to provide reference for the further development and application of hydrogel coatings.

Hydroxyapatite nucleation and growth modulated by amino acid-capped gold nanoparticles: An in vitro study

Surface modification of biomaterials significantly influences implantable materials' surface reactivity to induce an apatite-like layer formation. This study observed the bioactivity and surface reactivity of modified biomaterials (calcium-deficient hydroxyapatite [CDHA] on amino acid-capped AuNPs [AA-AuNPs]) through immersion in simulated body fluid (SBF). AuNPs capped with eight different amino acids (AA)—both charged and polar uncharged AAs—showed the ability to induce the biomimetic hydroxyapatite formation. The presence of a hydroxyapatite peak in the X-ray powder diffraction (XRD) pattern indicated hydroxyapatite formation after all samples’ immersion in SBF. Moreover, longer immersion time in SBF contributed to the nucleation and growth of hydroxyapatite shown by the changing of the crystal structure including lattice parameters, crystallinity index, and crystallite size. The XRD results confirmed that surface modification using AA-AuNPs significantly affected the orientation of the hydroxyapatite crystal, where AAs served as a binding site for Ca2+ and PO43− ions. Furthermore, grayscale analysis based on scanning electron microscope images showed that charged AAs exhibited a role in hydroxyapatite nucleation and growth while polar uncharged AAs only contributed to hydroxyapatite growth. The calculated Ca/P ratio also confirmed the formation of hydroxyapatite from CDHA. XRD and scanning electron microscopy/energy-dispersive X-ray spectroscopy results signify the bioactivity of CDHA-modulated AA-AuNPs in hydroxyapatite formation for new bone tissue regeneration.

Surface modifications of biomaterials in different applied fields.

Biomaterial implantation into the human body plays a key role in the medical field and biological applications. Increasing the life expectancy of biomaterial implants, reducing the rejection reaction inside the human body and reducing the risk of infection are the problems in this field that need to be solved urgently. The surface modification of biomaterials can change the original physical, chemical and biological properties and improve the function of materials. This review focuses on the application of surface modification techniques in various fields of biomaterials reported in the past few years. The surface modification techniques include film and coating synthesis, covalent grafting, self-assembled monolayers (SAMs), plasma surface modification and other strategies. First, a brief introduction to these surface modification techniques for biomaterials is given. Subsequently, the review focuses on how these techniques change the properties of biomaterials, and evaluates the effects of modification on the cytocompatibility, antibacterial, antifouling and surface hydrophobic properties of biomaterials. In addition, the implications for the design of biomaterials with different functions are discussed. Finally, based on this review, it is expected that the biomaterials have development prospects in the medical field.

Antibacterial and Proliferative Effects of NaOH-Coated Titanium, Zirconia, and Ceramic-Reinforced PEEK Dental Composites on Bone Marrow Mesenchymal Stem Cells.

Several metallic and polymer-based implants have been fabricated for orthopedic applications. For instance, titanium (Ti), zirconia (Zr), and polyetheretherketone (PEEK) are employed due to their excellent biocompatibility properties. Hence, the present study aimed to compare the functional and biological properties of these three biomaterials with surface modification. For this purpose, Ti, Zr, and ceramic-reinforced PEEK (CrPEEK) were coated with NaOH and tested for the biological response. Our results showed that the surface modification of these biomaterials significantly improved the water contact, protein adhesion, and bioactivity compared with uncoated samples. Among the NaOH-coated biomaterials, Ti and CrPEEK showed higher protein absorption than Zr. However, the mineral binding ability was higher in CrPEEK than in the other two biomaterials. Although the coating improved the functional properties, NaOH coating did not influence the antibacterial effect against E. coli and S. aureus in these biomaterials. Similar to the antibacterial effects, the NaOH coating did not contribute any significant changes in cell proliferation and cell loading, and CrPEEK showed better biocompatibility among the biomaterials. Therefore, this study concluded that the surface modification of biomaterials could potentially improve the functional properties but not the antibacterial and biocompatibility, and CrPEEK could be an alternative material to Ti and Zr with desirable qualities in orthopedic applications.

Topographical cues of PLGA membranes modulate the behavior of hMSCs, myoblasts and neuronal cells

Biomaterial surface modification through the introduction of defined and repeated patterns of topography helps study cell behavior in response to defined geometrical cues. The lithographic molding technique is widely used for conferring biomaterial surface microscale cues and enhancing the performance of biomedical devices. In this work, different master molds made by UV mask lithography were used to prepare poly (D,L-lactide-co-glycolide) - PLGA micropatterned membranes to present different features of topography at the cellular interface: channels, circular pillars, rectangular pillars, and pits. The effects of geometrical cues were investigated on different cell sources, such as neuronal cells, myoblasts, and stem cells. Morphological evaluation revealed a peculiar cell arrangement in response to a specific topographical stimulus sensed over the membrane surface. Cells seeded on linear-grooved membranes showed that this cue promoted elongated cell morphology. Rectangular and circular pillars act instead as discontinuous cues at the cell-membrane interface, inducing cell growth in multiple directions. The array of pits over the surface also highlighted the precise spatiotemporal organization of the cell; they grew between the interconnected membrane space within the pits, avoiding the microscale hole. The overall approach allowed the evaluation of the responses of different cell types adhered to various surface patterns, build-up on the same polymeric membrane, and disclosing the effect of specific topographical features. We explored how various microtopographic signals play distinct roles in different cells, thus affecting cell adhesion, migration, differentiation, cell-cell interactions, and other metabolic activities.

Comparative study of biomaterial surface modification due to subcritical CO2 and autoclave disinfection treatments

The decontamination of medical tools is a sustainable alternative to the use of disposable items. Sub- and supercritical fluids can be applied to decontaminate the surfaces of most biomedical materials with relative instrumental simplicity and moderate capital and operational costs, and offers a promising alternative to autoclavation. For future adaption it is important to assess the extent of material surface degradation, since CO2 has corrosion potential against metals and is soluble in polymers, and also forms a weak acid in the presence of residual humidity. Experimental results are reported for subcritical CO2 (37 oC, 50 bar, 2 h) decontamination of surgical stainless steel, Ti-6Al-4V alloy, PEEK polymer, ZrO2 ceramic and natural tooth enamel specimens seeded with E. coli, St. aureus, Pr. intermedia and C. albicans sealed inside polymer-paper packages during 1, 2, 5 and 10 cycles of treatment. Characterization by SEM and nanoindentation revealed that detectable alterations could be found only after the first cycle of treatment, whilst subsequent 10 treatment cycles did not cause further change. The findings provide a good basis for ongoing research into the potential of the supercritical fluid decontamination.

Evaluation of the Cathodic Electrodeposition Effectiveness of the Hydroxyapatite Layer Used in Surface Modification of Ti6Al4V-Based Biomaterials.

The important issue associated with the design and the fabrication of the titanium and titanium alloy implants is the increase of their biointegration with bone tissue. In the presented paper, the research results concerning the conditions used in the cathodic deposition of hydroxyapatite on the surface Ti6Al4V substrates primarily modified by the production of TiO2 nanoporous coatings, TiO2 nanofibers, and titanate coatings, are discussed. Despite excellent biocompatibility with natural bone tissue of materials based on hydroxyapatite (HA), their poor adhesion to the substrate caused the limited use in the implants’ construction. In our works, we have focused on the comparison of the structure, physicochemical, and mechanical properties of coating systems produced at different conditions. For this purpose, scanning electron microscopy images, chemical composition, X-ray diffraction patterns, infrared spectroscopy, wettability, and mechanical properties are analyzed. Our investigations proved that the intermediate titanium oxide coatings presence significantly increases the adhesion between the hydroxyapatite layer and the Ti6Al4V substrate, thus solving the temporary delamination problems of the HA layer.