In vitro hemocompatibility testing of biomaterials according to the ISO 10993-4

Bioinspired superhydrophobic surfaces with silver and nitric oxide-releasing capabilities to prevent device-associated infections and thrombosis

Bacteria-associated infections and thrombus formation are the two major complications plaguing the application of blood-contacting medical devices. Therefore, functionalized surfaces and drug delivery for passive and active antifouling strategies have been employed. Herein, we report the novel integration of bio-inspired superhydrophobicity with nitric oxide release to obtain a functional polymeric material with anti-thrombogenic and antimicrobial characteristics. The nitric oxide release acts as an antimicrobial agent and platelet inhibitor, while the superhydrophobic components prevent non-specific biofouling. Widely used medical-grade silicone rubber (SR) substrates that are known to be susceptible to biofilm and thrombus formation were dip-coated with fluorinated silicon dioxide (SiO2) and silver (Ag) nanoparticles (NPs) using an adhesive polymer as a binder. Thereafter, the resulting superhydrophobic (SH) SR substrates were impregnated with S-nitroso-N-acetylpenicillamine (SNAP, an NO donor) to obtain a superhydrophobic, Ag-bound, NO-releasing (SH-SiAgNO) surface. The SH-SiAgNO surfaces had the lowest amount of viable adhered E. coli (> 99.9 % reduction), S. aureus (> 99.8 % reduction), and platelets (> 96.1 % reduction) as compared to controls while demonstrating no cytotoxic effects on fibroblast cells. Thus, this innovative approach is the first to combine SNAP with an antifouling SH polymer surface that possesses the immense potential to minimize medical device-associated complications without using conventional systemic anticoagulation and antibiotic treatments.

Enzyme-loaded rod-like microgel shapes: a step towards the creation of shape-specific microreactors for blood detoxification purposes

Rapid removal of toxic substances is crucial to restore the normal functions of our body and ensure survival. Due to their high substrate specificity and catalytic efficiency, enzymes are unique candidates to deplete toxic compounds. While enzymes display several limitations including low stability and high immunogenicity, these can be overcome by entrapping them in a diverse range of carriers. The resulting micro/nanoreactors shield the enzymes from their surroundings, preventing their misfolding or denaturation thus allowing them to conduct their function. The micro/nanoreactors must circulate in the blood stream for extended periods of time to ensure complete depletion of the toxic agents. Surprisingly, while it is widely acknowledged that non-spherical carriers exhibit longer residence time in the bloodstream than their spherical counterparts, so far, all the reported micro/nanoreactors have been assembled with a spherical architecture. Herein, we address this important issue by pioneering the first shape-specific microreactors. We use UV-assisted punching to create rod-like microgel shapes with dimensions of 8 μm × 1 μm × 2 μm and demonstrate their biocompatibility by conducting hemolysis and cell viability assays with a macrophage and an endothelial cell line. Upon encapsulation of the model enzyme β-lactamase, the successful fabrication of rod-shaped microreactors is demonstrated by their ability to convert the yellow nitrocefin substrate into its hydrolyzed product.

In vitro cytotoxicity of magnetic-fluorescent bioactive glasses on SaOS-2, MC3T3-E1, BJ fibroblast cells, their hemolytic activity, and sorafenib release behavior

In the study, the fabrication of superparamagnetic-fluorescent bioactive glasses in the form of the particle, nanofiber, and 3D scaffolds was performed by including maghemite (γ-Fe2O3) nanoparticles and photoluminescent rare earth element ions (Eu3+, Gd3+, and Yb3+) using sol-gel, electrospinning, and robocasting techniques, respectively. The in vitro cytotoxicity of the magnetic-fluorescent bioactive glasses on osteosarcoma SaOS-2, pre-osteoblast MC3T3-E1, and BJ fibroblast cells, as well as their hemolytic activity and sorafenib tosylate loading and release behavior, were investigated. The cytotoxicity of the bioactive glass samples was tested using the MTT assay. Additionally, the alkaline phosphatase activity of the studied glasses was examined as a function of time. The mineralization behavior of the pre-osteoblast cell-seeded glass samples was analyzed using Alizarin red S staining. Results revealed that the in vitro cytotoxicity of the studied bioactive glasses in the form of particles and nanofibers depended on the sample concentration, whereas in the case of the 3D scaffolds, no cytotoxic response was observed on the osteosarcoma, pre-osteoblast, and fibroblast cells. Similarly, particle and nanofiber-based glass samples induced dose-dependent hemolysis on red blood cells. Drug loading rates were much lower for the 3D scaffolds compared to the particle and nanofiber-based samples. Drug release rates ranged from 25 % to 90 %, depending on the bioactive glass morphology and the pH of the release medium. It was concluded that the studied bioactive glasses have the potential to be used in tissue engineering applications and cancer therapy.

Thermal spray processes influencing surface chemistry and in-vitro hemocompatibility of hydroxyapatite-based orthopedic implants

Orthopedic implants made from titanium are a popular choice in the medical field because of their remarkable strength-to-weight ratio. Nevertheless, they may not interact well with human blood, resulting in thrombosis and hemolysis. In fact, non-hemocompatibility is believed to be responsible for about 31 % of medical device failures in the US alone, requiring painful and expensive revision surgery. To address this issue, bioactive hydroxyapatite coatings are applied to Ti-6Al-4V implants using thermal spray techniques. However, the temperature used during thermal processing impacts the coating's surface properties, affecting the mechanical and biological properties. Furthermore, the effectiveness of HA coatings on titanium for orthopedic applications has not been validated by biocompatibility tests, particularly hemocompatibility. In this study, we aimed to investigate the relative efficacy of three thermal spray processes of different temperature ranges: Atmospheric plasma spray (APS) (high temperature), Flame spray (FS) (moderate temperature), and High-Velocity Oxy-Fuel spray (HVOF) (low temperature), and study their impact on coating's surface properties, affecting blood components and implant's strength. The crystallinity of the HA coating increased by 32 % with a decrease in the operating temperature (APS < FS < HVOF). HVOF coating exhibited a ~ 34 % and ~ 120 % improvement in adhesion strength and ~ 31 % and 59 % increment in hardness compared to APS and FS coating, respectively, attributed to its low porosity, low coating thickness (~55 μm), and high degree of crystallinity. The HVOF coating showcased a significant increase in non-hemolytic behavior, with hemolysis rates ~8 and ~ 11 times lower than APS and FS coatings, respectively, owing to its smooth texture and high degree of crystallinity (p < 0.05). Furthermore, the HVOF coating exhibited minimal blood clotting based on the whole blood clotting assay, again confirmed by PT and aPTT assays showing delayed clotting time, indicating its non-thrombogenic behavior. The number of platelets adhered to the three coatings showed no significant difference compared to Ti-6Al-4V. APS and FS coatings showed low platelet activation, unlike HVOF coating and titanium, which revealed round platelets, similar to the negative control. Neither titanium nor HA coatings exhibited antibacterial properties, which may be due to their high affinity for organic substances, which promotes bacterial adhesion and replication. Among the three thermal processes, HVOF coating displayed good apatite growth, non-hemolytic, and non-thrombogenicity with no platelet activation owing to its low processing temperature, high degree of crystallinity (89.7 %), hydrophilicity, smooth (~4 μm) and dense (~97 %) microstructural properties. The results demonstrated that the HVOF-HA coating presented in this work meets the hemocompatible requirements and shows promise for prospective application as an orthopedic implant. Furthermore, this study has the potential to significantly reduce the use of animals in in-vivo research and improve their welfare while also cutting costs.

Erythrocyte Vulnerability to Airborne Nanopollutants

The toxicological impact of airborne polluting ultrafine particles (UFPs, also classified as nanoparticles with average sizes of less than 100 nm) is an emerging area of research pursuing a better understanding of the health hazards they pose to humans and other organisms. Hemolytic activity is a toxicity parameter that can be assessed quickly and easily to establish part of a nanoparticle's behavior once it reaches our circulatory system. However, it is exceedingly difficult to determine to what extent each of the nanoparticles present in the air is responsible for the detrimental effects exhibited. At the same time, current hemolytic assessment methodologies pose a series of limitations for the interpretation of results. An alternative is to synthesize nanoparticles that model selected typical types of UFPs in air pollution and evaluate their individual contributions to adverse health effects under a clinical assay of osmotic fragility. Here, we discuss evidence pointing out that the absence of hemolysis is not always a synonym for safety; exposure to model nanopollutants, even at low concentrations, is enough to increase erythrocyte susceptibility and dysfunction. A modified osmotic fragility assay in combination with a morphological inspection of the nanopollutant-erythrocyte interaction allows a richer interpretation of the exposure outcomes. Membrane-nanoparticle interplay has a leading role in the vulnerability observed. Therefore, future research in this line of work should pay special attention to the evaluation of the mechanisms that cause membrane damage.

Unravelling Surface Modification Strategies for Preventing Medical Device-Induced Thrombosis

The use of biomaterials in implanted medical devices remains hampered by platelet adhesion and blood coagulation. Thrombus formation is a prevalent cause of failure of these blood-contacting devices. Although systemic anticoagulant can be used to support materials and devices with poor blood compatibility, its negative effects such as an increased chance of bleeding, make materials with superior hemocompatibility extremely attractive, especially for long-term applications. This review examines blood-surface interactions, the pathogenesis of clotting on blood-contacting medical devices, popular surface modification techniques, mechanisms of action of anticoagulant coatings, and discusses future directions in biomaterial research for preventing thrombosis. In addition, this paper comprehensively reviews several novel methods that either entirely prevent interaction between material surfaces and blood components or regulate the reaction of the coagulation cascade, thrombocytes, and leukocytes.

Optimization of Metal Ion/Fuel Ratio for an Effective Combustion of Monticellite and Investigation of Its Microbial and Hemolytic Activity for Biomedical Applications

Bioactive silicates have gained popularity as bone graft substitutes in recent years due to their exceptional ability to bind to host tissues. The current study investigates the effect of changing the metal ion-to-fuel ratio on the properties and biological activity of monticellite prepared via the sol-gel connived combustion technique. Single-phasic monticellite was obtained at 900 °C, without any secondary-phase contaminants for the fuel-lean, stoichiometric, and fuel-rich conditions. SEM and TEM micrographs revealed the porous, spongy morphology of the materials. Because of the reduced crystallite size and higher surface area, the biomineralization of monticellite prepared under fuel-lean conditions resulted in more apatite deposition than those of the other two samples. The results show that the material has a good compressive strength comparable to natural bone, while its brittleness is equivalent to the lower moduli of bone. In terms of antibacterial and antifungal activities, the monticellite bioceramics outperformed the clinical pathogens. It can be used for bone tissue engineering and other biological applications due to its excellent anti-inflammatory and hemolysis inhibitory properties.

Physiomimetic biocompatibility evaluation of directly printed degradable porous iron implants using various cell types

Additively manufactured (AM) degradable porous metallic biomaterials offer unique opportunities for satisfying the design requirements of an ideal bone substitute. Among the currently available biodegradable metals, iron has the highest elastic modulus, meaning that it would benefit the most from porous design. Given the successful preclinical applications of such biomaterials for the treatment of cardiovascular diseases, the moderate compatibility of AM porous iron with osteoblast-like cells, reported in earlier studies, has been surprising. This may be because, as opposed to static in vitro conditions, the biodegradation products of iron in vivo are transported away and excreted. To better mimic the in situ situations of biodegradable biomaterials after implantation, we compared the biodegradation behavior and cytocompatibility of AM porous iron under static conditions to the conditions with dynamic in situ-like fluid flow perfusion in a bioreactor. Furthermore, the compatibility of these scaffolds with four different cell types was evaluated to better understand the implications of these implants for the complex process of natural wound healing. These included endothelial cells, L929 fibroblasts, RAW264.7 macrophage-like cells, and osteoblastic MG-63 cells. The biodegradation rate of the scaffolds was significantly increased in the perfusion bioreactor as compared to static immersion. Under either condition, the compatibility with L929 cells was the best. Moreover, the compatibility with all the cell types was much enhanced under physiomimetic dynamic flow conditions as compared to static biodegradation. Our study highlights the importance of physiomimetic culture conditions and cell type selection when evaluating the cytocompatibility of degradable biomaterials in vitro. STATEMENT OF SIGNIFICANCE: Additively manufactured (AM) degradable porous metals offer unique opportunities for the treatment of large bony defects. Despite the successful preclinical applications of biodegradable iron in the cardiovascular field, the moderate compatibility of AM porous iron with osteoblast-like cells was reported. To better mimic the in vivo condition, we compared the biodegradation behavior and cytocompatibility of AM porous iron under static condition to dynamic perfusion. Furthermore, the compatibility of these scaffolds with various cell types was evaluated to better simulate the process of natural wound healing. Our study suggests that AM porous iron holds great promise for orthopedic applications, while also highlighting the importance of physio-mimetic culture conditions and cell type selection when evaluating the cytocompatibility of degradable biomaterials in vitro.

A PDA-Functionalized 3D Lung Scaffold Bioplatform to Construct Complicated Breast Tumor Microenvironment for Anticancer Drug Screening and Immunotherapy

2D cell culture occupies an important place in cancer progression and drug discovery research. However, it limitedly models the "true biology" of tumors in vivo. 3D tumor culture systems can better mimic tumor characteristics for anticancer drug discovery but still maintain great challenges. Herein, polydopamine (PDA)-modified decellularized lung scaffolds are designed and can serve as a functional biosystem to study tumor progression and anticancer drug screening, as well as mimic the tumor microenvironment. PDA-modified scaffolds with strong hydrophilicity and excellent cell compatibility can promote cell growth and proliferation. After 96 h treatment with 5-FU, cisplatin, and DOX, higher survival rates in PDA-modified scaffolds are observed compared to nonmodified scaffolds and 2D systems. The E-cadhesion formation, HIF-1α-mediated senescence decrease, and tumor stemness enhancement can drive drug resistance and antitumor drug screening of breast cancer cells. Moreover, there is a higher survival rate of CD45+ /CD3+ /CD4+ /CD8+ T cells in PDA-modified scaffolds for potential cancer immunotherapy drug screening. This PDA-modified tumor bioplatform will supply some promising information for studying tumor progression, overcoming tumor resistance, and screening tumor immunotherapy drugs.

Evaluation of Biocompatibility of PLA/PHB/TPS Polymer Scaffolds with Different Additives of ATBC and OLA Plasticizers

One of the blends that is usable for 3D printing while not being toxic to cell cultures is the lactic acid (PLA)/polyhydroxybutyrate (PHB)/thermoplastic starch (TPS) blend. The addition of plasticizers can change the rate of biodegradation and the biological behavior of the material. In order to evaluate the potential of the PLA/PHB/TPS material in combination with additives (plasticizers: acetyl tributyl citrate (ATBC) and oligomeric lactic acid (OLA)), for use in the field of biomedical tissue engineering, we performed a comprehensive in vitro characterization of selected mixture materials. Three types of materials were tested: I: PLA/PHB/TPS + 25% OLA, II: PLA/PHB/TPS + 30% ATBC, and III: PLA/PHB/TPS + 30% OLA. The assessment of the biocompatibility of the materials included cytotoxicity tests, such as monitoring the viability, proliferation and morphology of cells and their deposition on the surface of the materials. The cell line 7F2 osteoblasts (Mus musculus) was used in the experiments. Based on the test results, the significant influence of plasticizers on the material was confirmed, with their specific proportions in the mixtures. PLA/PHB/TPS + 25% OLA was evaluated as the optimal material for biocompatibility with 7F2 osteoblasts. The tested biomaterials have the potential for further investigation with a possible change in the proportion of plasticizers, which can have a fundamental impact on their biological properties.

Bone-Targeted Dual Functional Lipid-coated Drug Delivery System for Osteosarcoma Therapy

PURPOSE OR OBJECTIVE

Osteosarcoma is well-known for its high incidence in children and adolescents and long-term bone pain, which seriously reduces the life quality of patients. Cisplatin (CDDP), as the first-line anti-osteosarcoma drug, has been used in many anticancer treatments. At the same time, the serious side effects of platinum (Pt) drugs have also attracted widespread attention. To accurately deliver Pt drugs to the lesion site and realize controlled release of Pt drugs, certain modified delivery systems have been extensively studied.

METHODS

Among them, liposomes have been approved for clinical cancer treatment due to their highly biocompatibility and superior modifiability. Here, we developed a bone-targeted dual functional lipid-coated drug delivery system, lipid-coated CDDP alendronate nanoparticles (LCA NPs) to target the bone and precisely deliver the drugs to the tumor site. Cell toxicity, apoptosis and cellular uptake were detected to evaluate the anticancer effect for LCA NPs. Furthermore, transwell assay and wound healing assay were conducted to estimate the osteosarcoma cell migration and invasion. Hemolysis assay was utilized to assess the biocapitibility of the kind of NPs.

RESULTS

With the aim of bone-targeted unit alendronate (ALD), LCA NPs serve as a rich bone homing Pt delivery system to exert efficient anticancer effects and synergistically reduce bone resorption and bone loss potentially.

CONCLUSIONS

By providing a highly biocompatible platform for osteosarcoma therapy, LCA NPs may help to significantly enhance the anticancer effect of Pt and greatly reduce the systemic toxicity and side effects of Pt towards osteosarcoma.

Molybdenum-Iodine Cluster Loaded Polymeric Nanoparticles Allowing a Coupled Therapeutic Action with Low Side Toxicity for Treatment of Ovarian Cancer

The ability of cancer cells to develop resistance to anti-cancer drugs, known as multidrug resistance, remains a major cause of tumor recurrence and cancer metastasis. This work explores the double mechanism of toxicity of (D, L-lactide-co-glycolide) acid (PLGA) nanoparticles encapsulating a molybdenum cluster compound, namely Cs₂[{Mo₆I₈}(OOCC₂F₅)₆] (CMIF). Hemocompatibility and biocompatibility assays show the safe potential of CMIF loaded nanoparticles (CNPs) as delivery systems intended for tumor targeting for PDT of ovarian cancer with a slight hemolytic activity and a lack of toxicity up to 50 µM CMIF concentration. Cellular uptake shows a preferential uptake of CNPs in lysosomes, which is not interfering with CMIF activity. The double mechanism of CNPs consists in a production of ROS and a DNA damage activity, from 5 µM and 0.5 µM respectively (CMIF concentration). The cellular death mechanism comprises 80% of necrosis and 20% of direct apoptosis by direct DNA damages. This work confirms CMIF loaded PLGA nanoparticles as an efficient and relevant delivery system for PDT.

A Biodegradable Flexible Micro/Nano-Structured Porous Hemostatic Dental Sponge

A biodegradable micro/nano-structured porous hemostatic gelatin-based sponge as a dentistry surgery foam was prepared using a freeze-drying method. In vitro function evaluation tests were performed to ensure its hemostatic effect. Biocompatibility tests were also performed to show the compatibility of the sponge on human fetal foreskin fibroblasts (HFFF2) cells and red blood cells (RBCs). Then, 10 patients who required the extraction of two teeth were selected, and after teeth extraction, for dressing, the produced sponge was placed in one of the extracavities while a commercial sponge was placed in the cavity in the other tooth as a control. The total weight of the absorbed blood in each group was compared. The results showed a porous structure with micrometric and nanometric pores, flexibility, a two-week range for degradation, and an ability to absorb blood 35 times its weight in vitro. The prepared sponge showed lower blood clotting times (BCTs) (243.33 ± 2.35 s) and a lower blood clotting index (BCI) (10.67 ± 0.004%) compared to two commercial sponges that displayed its ability for faster coagulation and good hemostatic function. It also had no toxic effects on the HFFF2 cells and RBCs. The clinical assessment showed a better ability of blood absorption for the produced sponge (p-value = 0.0015). The sponge is recommended for use in dental surgeries because of its outstanding abilities.

Molecular Characterization and Biocompatibility of Exopolysaccharide Produced by Moderately Halophilic Bacterium Virgibacillus dokdonensis from the Saltern of Kumta Coast

The use of natural polysaccharides as biomaterials is gaining importance in tissue engineering due to their inherent biocompatibility. In this direction, the present study aims to explore the structure and biocompatibility of the EPS produced by Virgibacillus dokdonensis VITP14. This marine bacterium produces 17.3 g/L of EPS at 96 h of fermentation. The EPS was purified using ion exchange and gel permeation chromatographic methods. The porous web-like structure and elemental composition (C, O, Na, Mg, P, S) of the EPS were inferred from SEM and EDX analysis. AFM analysis revealed spike-like lumps with a surface roughness of 84.85 nm. The zeta potential value of −10 mV indicates the anionic nature of the EPS. Initial molecular characterization showed that the EPS is a heteropolysaccharide composed of glucose (25.8%), ribose (18.6%), fructose (31.5%), and xylose (24%), which are the monosaccharide units in the HPLC analysis. The FTIR spectrum indicates the presence of functional groups/bonds typical of EPSs (O-H, C-H, C-O-H, C-O, S=O, and P=O). The polymer has an average molecular weight of 555 kDa. Further, NMR analysis revealed the monomer composition, the existence of two α- and six β-glycosidic linkages, and the branched repeating unit as → 1)[α-D-Xylp-(1 → 2)-α-D-Glcp-(1 → 6)-β-D-Glcp-(1 → 5)]-β-D-Frup-(2 → 2)[β-D-Xylp-(1 → 4)]-β-D-Xylp-(1 → 6)-β-D-Fruf-(2 → 4)-β-D-Ribp-(1 →. The EPS is thermally stable till 251.4 °C. X-ray diffraction analysis confirmed the semicrystalline (54.2%) nature of the EPS. Further, the EPS exhibits significant water solubility (76.5%), water-holding capacity (266.8%), emulsifying index (66.8%), hemocompatibility (erythrocyte protection > 87%), and cytocompatibility (cell viability > 80% on RAW264.7 and keratinocyte HaCaT cells) at higher concentrations and prolongs coagulation time in APTT and PT tests. Our research unveils the significant biocompatibility of VITP14 EPS for synthesizing a variety of biomaterials.

Hemocompatibility challenge of membrane oxygenator for artificial lung technology

The artificial lung (AL) technology is one of the membrane-based artificial organs that partly augments lung functions, i.e. blood oxygenation and CO₂ removal. It is generally employed as an extracorporeal membrane oxygenation (ECMO) device to treat acute and chronic lung-failure patients, and the recent outbreak of the COVID-19 pandemic has re-emphasized the importance of this technology. The principal component in AL is the polymeric membrane oxygenator that facilitates the O₂/CO₂ exchange with the blood. Despite the considerable improvement in anti-thrombogenic biomaterials in other applications (e.g., stents), AL research has not advanced at the same rate. This is partly because AL research requires interdisciplinary knowledge in biomaterials and membrane technology. Some of the promising biomaterials with reasonable hemocompatibility - such as emerging fluoropolymers of extremely low surface energy - must first be fabricated into membranes to exhibit effective gas exchange performance. As AL membranes must also demonstrate high hemocompatibility in tandem, it is essential to test the membranes using in-vitro hemocompatibility experiments before in-vivo test. Hence, it is vital to have a reliable in-vitro experimental protocol that can be reasonably correlated with the in-vivo results. However, current in-vitro AL studies are unsystematic to allow a consistent comparison with in-vivo results. More specifically, current literature on AL biomaterial in-vitro hemocompatibility data are not quantitatively comparable due to the use of unstandardized and unreliable protocols. Such a wide gap has been the main bottleneck in the improvement of AL research, preventing promising biomaterials from reaching clinical trials. This review summarizes the current state-of-the-art and status of AL technology from membrane researcher perspectives. Particularly, most of the reported in-vitro experiments to assess AL membrane hemocompatibility are compiled and critically compared to suggest the most reliable method suitable for AL biomaterial research. Also, a brief review of current approaches to improve AL hemocompatibility is summarized. STATEMENT OF SIGNIFICANCE: The importance of Artificial Lung (AL) technology has been re-emphasized in the time of the COVID-19 pandemic. The utmost bottleneck in the current AL technology is the poor hemocompatibility of the polymer membrane used for O₂/CO₂ gas exchange, limiting its use in the long-term. Unfortunately, most of the in-vitro AL experiments are unsystematic, irreproducible, and unreliable. There are no standardized in-vitro hemocompatibility characterization protocols for quantitative comparison between AL biomaterials. In this review, we tackled this bottleneck by compiling the scattered in-vitro data and suggesting the most suitable experimental protocol to obtain reliable and comparable hemocompatibility results. To the best of our knowledge, this is the first review paper focusing on the hemocompatibility challenge of AL technology.

Hemocompatibile Thin Films Assessed under Blood Flow Shear Forces

The aim of this study was to minimize the risk of life-threatening thromboembolism in the ventricle through the use of a new biomimetic heart valve based on metal-polymer composites. Finite volume element simulations of blood adhesion to the material were carried out, encompassing radial flow and the cone and plane test together with determination of the effect of boundary conditions. Both tilt-disc and bicuspid valves do not have optimized blood flow due to their design based on rigid valve materials (leaflet made of pyrolytic carbon). The main objective was the development of materials with specific properties dedicated to contact with blood. Materials were evaluated by dynamic tests using blood, concentrates, and whole human blood. Hemostability tests under hydrodynamic conditions were related to the mechanical properties of thin-film materials obtained from tribological tests. The quality of the coatings was high enough to avoid damage to the coating even as they were exposed up to maximum loading. Analysis towards blood concentrates of the hydrogenated carbon sample and the nitrogen-doped hydrogenated carbon sample revealed that the interaction of the coating with erythrocytes was the strongest. Hemocompatibility evaluation under hydrodynamic conditions confirmed very good properties of the developed coatings.

Hyaluronic acid (HA)-Gd(III) and HA-Fe(III) microgels as MRI contrast enhancing agents

Hyaluronic acid (HA) was crosslinked with Gd(III) and Fe(III) ions rendering physically crosslinked HA-metal(III) microgels as magnetic resonance imaging (MRI) enhancing contrast agents. These HA-Gd(III) and HA-Fe(III) microgels are injectable with size range, 50-5000 nm in water. The same isoelectric point, pH 1.2 ± 0.1, was measured for both microgels. HA-Gd(III) and HA-Fe(III) microgels are hemo-compatible biomaterials and can be safely used in intravascular applications up to 1000 μg/mL concentration. Furthermore, no significant toxicity was attained as 95 ± 8 and 81 ± 2% cell viability on L929 fibroblast cells at 100 μg/mL of HA-Gd(III) and HA-Fe(III) microgels were measured. Moreover, HA-Gd(III) microgels were found to afford significant contrast improvement capability in MRI with proton relaxivity, r₁ = 2.11 mM^-1 s^-1, comparable with the values reported for Gd(III) labeled functionalized HA gel systems and commercial Gd based contrast agents.

Biosafety evaluation of Li2Si2O5 whisker-reinforced glass-ceramics

Lithium disilicate (Li2Si2O5) glass-ceramic is a commonly used dental ceramic material. In this study, Li2Si2O5 whiskers were prepared by the hydrothermal method, mixed with Li2Si2O5 glass powders, and Li2Si2O5 whisker-reinforced glass-ceramics were prepared by reaction sintering. The biosafety of the new Li2Si2O5 glass-ceramics were evaluated by in vitro cytotoxicity, hemolysis, oral mucosal irritation, acute systemic toxicity, and subacute systemic toxicity (oral route) tests according to ISO 7405/ISO 10993 standards. The cytotoxicity test results showed that the cell growth of the experimental group was good, and the cell number and morphology were not significantly different from those of the blank group (P > 0.05). The toxicity grading for both experimental and blank control groups were 0. The hemolysis rate of the material was 1.25%, which indicated that it did not cause hemolytic reaction. The material was non-irritating to the oral mucosa. In acute systemic toxicity test, animals in the experimental group showed increased body weight, moved freely, with no signs of poisoning. The food utilization rate and relative growth rate (change of the weight) of rats in the subacute systemic toxicity test were not statistically different from those of the control group (P > 0.05). Preliminary evaluation of the biosafety of the Li2Si2O5 whisker-reinforced glass-ceramics showed that it met the existing regulatory standards, and further biosafety experiments can be conducted, following which the material may be expected to be applied in clinical practice.

Cationic Fluoropolyphosphazenes: Synthesis and Assembly with Heparin as a Pathway to Hemocompatible Nanocoatings

The development of state-of-the-art blood-contacting devices can be advanced through integrating hemocompatibility, durability, and anticoagulant functionalities within engineered nanoscale coatings. To enable all-aqueous assembly of nanocoatings combining omniphobic fluorinated features with the potent anticoagulant activity of hydrophilic heparin, two fluoropolymers containing cationic functionalities were synthesized─poly[(trifluoroethoxy)(dimethylaminopropyloxy)phosphazene], PFAP-O, and poly[(trifluoroethoxy)(dimethylaminopropylamino)phosphazene], PFAP-A. Despite a relatively high content of fluorinated pendant groups─approximately 50% (mol) in each─both polymers displayed solubility in aqueous solutions and were able to spontaneously form stable supramolecular complexes with heparin, as determined by dynamic light scattering and asymmetric flow field-flow fractionation methods. Heparin-containing coatings were then assembled by layer-by-layer deposition in aqueous solutions. Nanoassembled coatings were evaluated for potential thrombogenicity in three important categories of in vitro tests─coagulation by thrombin generation, platelet retention, and hemolysis. In all assays, heparin-containing fluoro-coatings consistently displayed superior performance compared to untreated titanium surfaces or fluoro-coatings assembled using poly(acrylic acid) in the absence of heparin. Short-term stability studies revealed the noneluting nature of these noncovalently assembled coatings.

Blood-incompatibility in haemodialysis: alleviating inflammation and effects of coagulation

Blood-incompatibility is an inevitability of all blood-contacting device applications and therapies, including haemodialysis (HD). Blood leaving the environment of blood vessels and the protection of the endothelium is confronted with several stimuli of the extracorporeal circuit (ECC), triggering the activation of blood cells and various biochemical pathways of plasma. Prevention of blood coagulation, a major obstacle that needed to be overcome to make HD possible, remains an issue to contend with. While anticoagulation (mainly with heparin) successfully prevents clotting within the ECC to allow removal of uraemic toxins across the dialysis membrane wall, it is far from ideal, triggering heparin-induced thrombocytopenia in some instances. Soluble fibrin can form even in the presence of heparin and depending on the constitution of the patient and activation of platelets, could result in physical clots within the ECC (e.g. bubble trap chamber) and, together with other plasma and coagulation proteins, result in increased adsorption of proteins on the membrane surface. The buildup of this secondary membrane layer impairs the transport properties of the membrane to reduce the clearance of uraemic toxins. Activation of complement system-dependent immune response pathways leads to leukopenia, formation of platelet–neutrophil complexes and expression of tissue factor contributing to thrombotic processes and a procoagulant state, respectively. Complement activation also promotes recruitment and activation of leukocytes resulting in oxidative burst and release of pro-inflammatory cytokines and chemokines, thereby worsening the elevated underlying inflammation and oxidative stress condition of chronic kidney disease patients. Restricting all forms of blood-incompatibility, including potential contamination of dialysis fluid with endotoxins leading to inflammation, during HD therapies is thus still a major target towards more blood-compatible and safer dialysis to improve patient outcomes. We describe the mechanisms of various activation pathways during the interaction between blood and components of the ECC and describe approaches to mitigate the effects of these adverse interactions. The opportunities to develop improved dialysis membranes as well as implementation strategies with less potential for undesired biological reactions are discussed.

Improvement of mechanical and antibacterial properties of porous nHA scaffolds by fluorinated graphene oxide

Nano-hydroxyapatite (nHA) is widely used as a bio-scaffold material due to its good bioactivity and biocompatibility. In this study, fluorinated graphene oxide (FG) was added to nHA to improve its poor formability, weak mechanical properties, undesirable antimicrobial activity and other disadvantages that affect its clinical application. FG was synthesized by a simple hydrothermal method. Novel porous composite scaffolds were prepared by adding different weight ratios (0.1 wt%, 0.5 wt% and 1 wt%) of FG to nHA using the 3D printing technique. The morphology, phase composition and mechanical properties of the composite scaffolds were characterized. In addition, the degradation performance of the composite scaffolds, antibacterial activity against Staphylococcus aureus and Escherichia coli, and cytocompatibility were also investigated. The results showed that the nHA/FG composite scaffold was successfully prepared with a uniform distribution of FG on the scaffold. The mechanical properties showed that the compression strength of the nHA/FG composite scaffold was significantly higher than that of the nHA scaffold (7.22 ± 1.43 MPa). The porosity of all composite scaffolds was above 70%. The addition of FG significantly improved the mechanical properties of the nHA scaffold without affecting the porosity of the scaffold. In addition, the 0.5 wt% nHA/FG scaffold exhibited satisfactory cytocompatibility and antibacterial properties. Therefore, the constructed nHA/FG composite scaffold can be considered as a novel antimicrobial bone substitute material with good application prospects.

Nano-hydroxyapatite (nHA) is widely used as a bio-scaffold material. In this study, fluorinated graphene oxide (FG) was added to nHA to improve its poor formability, weak mechanical properties and undesirable antimicrobial activity that affect its clinical application.

Biocompatibility testing of composite biomaterial designed for a new petal valve construction for pulsatile ventricular assist device

This paper presents the results of biocompatibility testing performed on several biomaterial variants for manufacturing a newly designed petal valve intended for use in a pulsatile ventricular assist device or blood pump. Both physical vapor deposition (PVD) and plasma-enhanced chemical vapor deposition (PECVD) were used to coat titanium-based substrates with hydrogenated tetrahedral amorphous carbon (ta-C:H) or amorphous hydrogenated carbon (a-C:H and a-C:H, N). Experiments were carried out using whole human blood under arterial shear stress conditions in a cone-plate analyzer (ap. 1800 1/s). In most cases, tested coatings showed good or very good haemocompatibility. Type a-C:H, N coating proved to be superior in terms of activation, risk of aggregation, and the effects of generating microparticles of apoptotic origin, and also demonstrated excellent mechanical properties. Therefore, a-C:H, N coatings were selected for further in vivo studies. In vivo animal studies were carried out according to the ISO 10993 standard. Intradermal reactivity was assessed in three rabbits and sub-acute toxicity and local effects after implantation were examined in 12 rabbits. Based on postmortem examination, no organ failure or wound tissue damage occurred during the required period of observation. In summary, our investigations demonstrated high biocompatibility of the biomaterials in relation to thrombogenicity, toxicity, and wound healing. Prototypes of the petal valves were manufactured and mounted on the pulsatile ventricular assist device. Hydrodynamic features and impact on red blood cells (hemolysis) as well as coagulation (systemic thrombogenicity) were assessed in whole blood.

Novel dental implant modifications with two-staged double benefits for preventing infection and promoting osseointegration in vivo and in vitro

Peri-implantitis are a major problem causing implant failure these days. Accordingly, anti-infection during the early stage and subsequent promotion of osseointegration are two main key factors to solve this issue. Micro-arc oxidation (MAO) treatment is a way to form an oxidation film on the surface of metallic materials. The method shows good osteogenic properties but weak antibacterial effect. Therefore, we developed combined strategies to combat severe peri-implantitis, which included the use of a novel compound, PD, comprising dendrimers poly(amidoamine) (PAMAM) loading dimethylaminododecyl methacrylate (DMADDM) as well as MAO treatment. Here, we explored the chemical properties of the novel compound PD, and proved that this compound was successfully synthesized, with the loading efficiency and encapsulation efficiency of 23.91% and 31.42%, respectively. We further report the two-stage double benefits capability of PD + MAO: (1) in the first stage, PD + MAO could decrease the adherence and development of biofilms by releasing DMADDM in the highly infected first stage after implant surgery both in vitro and in vivo; (2) in the second stage, PD + MAO indicated mighty anti-infection and osteoconductive characteristics in a rat model of peri-implantitis in vivo. This study first reports the two-staged, double benefits of PD + MAO, and demonstrates its potential in clinical applications for inhibiting peri-implantitis, especially in patients with severe infection risk.

Emodin-Conjugated PEGylation of Fe3O4 Nanoparticles for FI/MRI Dual-Modal Imaging and Therapy in Pancreatic Cancer

BACKGROUND

Pancreatic cancer (PC) remains a difficult tumor to diagnose and treat. It is often diagnosed as advanced by reason of the anatomical structure of the deep retroperitoneal layer of the pancreas, lack of typical symptoms and effective screening methods to detect this malignancy, resulting in a low survival rate. Emodin (EMO) is an economical natural product with effective treatment and few side effects of cancer treatment. Magnetic nanoparticles (MNPs) can achieve multiplexed imaging and targeted therapy by loading a wide range of functional materials such as fluorescent dyes and therapeutic agents.

PURPOSE

The purpose of this study was to design and evaluate a multifunctional theranostic nanoplatform for PC diagnosis and treatment.

METHODS

In this study, we successfully developed EMO-loaded, Cy7-functionalized, PEG-coated Fe₃O₄ (Fe₃O₄-PEG-Cy7-EMO). Characteristics including morphology, hydrodynamic size, zeta potentials, stability, and magnetic properties of Fe₃O₄-PEG-Cy7-EMO were evaluated. Fluorescence imaging (FI)/magnetic resonance imaging (MRI) and therapeutic treatment were examined in vitro and in vivo.

RESULTS

Fe₃O₄-PEG-Cy7-EMO nanoparticles had a core size of 9.9 ± 1.2 nm, which showed long-time stability and FI/MRI properties. Bio-transmission electron microscopy (bio-TEM) results showed that Fe₃O₄-PEG-Cy7-EMO nanoparticles were endocytosed into BxPC-3 cells, while few were observed in hTERT-HPNE cells. Prussian blue staining also confirmed that BxPC-3 cells have a stronger phagocytic ability as compared to hTERT-HPNE cells. Additionally, Fe₃O₄-PEG-Cy7-EMO had a stronger inhibition effect on BxPC-3 cells than Fe₃O₄-PEG and EMO. The hemolysis experiment proved that Fe₃O₄-PEG-Cy7-EMO can be used in vivo experiments. In vivo analysis demonstrated that Fe₃O₄-PEG-Cy7-EMO enabled FI/MRI dual-modal imaging and targeted therapy in pancreatic tumor xenografted mice.

CONCLUSION

Fe₃O₄-PEG-Cy7-EMO may serve as a potential theranostic nanoplatform for PC.

Characterization of a Sandwich PLGA-Gallic Acid-PLGA Coating on Mg Alloy ZK60 for Bioresorbable Coronary Artery Stents

Absorbable magnesium stents have become alternatives for treating restenosis owing to their better mechanical properties than those of bioabsorbable polymer stents. However, without modification, magnesium alloys cannot provide the proper degradation rate required to match the vascular reform speed. Gallic acid is a phenolic acid with attractive biological functions, including anti-inflammation, promotion of endothelial cell proliferation, and inhibition of smooth muscle cell growth. Thus, in the present work, a small-molecule eluting coating is designed using a sandwich-like configuration with a gallic acid layer enclosed between poly (d,l-lactide-co-glycolide) layers. This coating was deposited on ZK60 substrate, a magnesium alloy that is used to fabricate bioresorbable coronary artery stents. Electrochemical analysis showed that the corrosion rate of the specimen was ~2000 times lower than that of the bare counterpart. The released gallic acid molecules from sandwich coating inhibit oxidation by capturing free radicals, selectively promote the proliferation of endothelial cells, and inhibit smooth muscle cell growth. In a cell migration assay, sandwich coating delayed wound closure in smooth muscle cells. The sandwich coating not only improved the corrosion resistance but also promoted endothelialization, and it thus has great potential for the development of functional vascular stents that prevent late-stent restenosis.

Erythrocytes as model cells for biocompatibility assessment, cytotoxicity screening of xenobiotics and drug delivery

Erythrocytes (RBCs) represent the main cell component in circulation and recently have become a topic of intensive scientific interest. The relevance of erythrocytes as a model for cytotoxicity screening of xenobiotics is under the spotlight of this review. Erythrocytes constitute a fundamental cellular model to study potential interactions with blood components of manifold novel polymer or biomaterials. Morphological changes, subsequent disruption of RBC membrane integrity, and hemolysis could be used to determine the cytotoxicity of various compounds. Erythrocytes undergo a programmed death (eryptosis) which could serve as a good model for evaluating certain mechanisms which correspond to apoptosis taking place in nucleated cells. Importantly, erythrocytes can be successfully used as a valuable cellular model in examination of oxidative stress generated by certain diseases or multiple xenobiotics since red cells are subjected to permanent oxidative stress. Additionally, the antioxidant capacity of erythrocytes, and the activity of anti-oxidative enzymes could reflect reactive oxygen species (ROS) generating properties of various substances and allow to determine their effects on tissues. The last part of this review presents the latest findings on the possible application of RBCs as drug delivery systems (DDS). In conclusion, all these findings make erythrocytes highly valuable cells for in vitro biocompatibility assessment, cytotoxicity screening of a wide variety of substances as well as drug delivery.

Effect of the mechanical properties of carbon-based coatings on the mechanics of cell-material interactions

The paper presents an influence of the surface mechanical properties of thin-film materials on blood cell adhesion under shear stress conditions. Physical vapour deposited (PVD) coatings i.e. hydrogenated amorphous carbon (a-C:H) doped with nitrogen or silicon have been investigated. The mechanical properties of materials, namely their microhardness and Young's modulus were measured using indentation test with Rockwell indenter. The adhesion efficiency of blood cells in dynamic conditions were analysed using a radial flow chamber. Red blood cells (RBC) were used as representative cells to analyse cell-material interactions. The biomaterial examinations were performed under physiological flow conditions at the single-cell level. The 3D FVM (finite volume method) model of multi-phase radial flow test was developed to reproduce the physical test and to predict distributions of shear stresses and velocity during blood washout with PBS. Cell-material interactions were found to be strongly associated with the mechanical properties of the thin-film material. The decrease in the hardness of the coatings translated into a weaker cell - material interactions.

Next-generation tissue-engineered heart valves with repair, remodelling and regeneration capacity

Valvular heart disease is a major cause of morbidity and mortality worldwide. Surgical valve repair or replacement has been the standard of care for patients with valvular heart disease for many decades, but transcatheter heart valve therapy has revolutionized the field in the past 15 years. However, despite the tremendous technical evolution of transcatheter heart valves, to date, the clinically available heart valve prostheses for surgical and transcatheter replacement have considerable limitations. The design of next-generation tissue-engineered heart valves (TEHVs) with repair, remodelling and regenerative capacity can address these limitations, and TEHVs could become a promising therapeutic alternative for patients with valvular disease. In this Review, we present a comprehensive overview of current clinically adopted heart valve replacement options, with a focus on transcatheter prostheses. We discuss the various concepts of heart valve tissue engineering underlying the design of next-generation TEHVs, focusing on off-the-shelf technologies. We also summarize the latest preclinical and clinical evidence for the use of these TEHVs and describe the current scientific, regulatory and clinical challenges associated with the safe and broad clinical translation of this technology.

Safety assessment of a newly synthesized copolymer for micellar delivery of hydrophobic caffeic acid phenethyl ester

Caffeic acid phenethyl ester (CAPE), a major pharmacologically active component of poplar type propolis, is known for its proapoptotic, anti-inflammatory, antioxidant, antiviral, and enzyme inhibiting activities. The aim of this study was to perform an in vitro and in vivo safety assessment of a micellar system based on a newly synthesized copolymer, consisting of polyglycidol and poly(allyl glycidyl ether) (C₁₂-PAGE-PG) as a drug delivery platform for CAPE. The in vitro studies on HepG2 and L929 cells by MTT and LDH assays after treatment with the empty and CAPE-loaded micelles showed no cytotoxic effects of the empty micelles and retained cytotoxic activity of CAPE loaded in the micelles. No hemolysis or stimulation of mouse lymphocytes or macrophages was observed in vitro. In vivo hematological, biochemical, and histological assays on rats, treated with the empty (2580 and 5160 µg/kg) or CAPE-loaded (375 and 750 µg CAPE/kg) micelles did not reveal pathological changes of any of the parameters assayed after 14-days' treatment. In conclusion, initial toxicological data characterize C₁₂-PAGE-PG as a non-toxic and promising copolymer for development of micellar drug delivery systems, particularly for a hydrophobic active substance as CAPE.

Doping Polysulfone Membrane with Alpha-Tocopherol and Alpha-Lipoic Acid for Suppressing Oxidative Stress Induced by Hemodialysis Treatment

The reduction of free radicals by bioactive membranes used for hemodialysis treatment is an important topic due to the constant rise of oxidative stress-associated cardiovascular mortality by hemodialysis patients. Therefore, it is urgent to find an effective solution that helps to solve this problem. Polysulfone membranes enriched with α-lipoic acid, α-tocopherol, and with both components are fabricated by spin coating. The antioxidant properties of these membranes are evaluated in vitro by determining the lipid-peroxidation level and the total antioxidant status of the blood plasma. The biocompatibility is assessed by quantifying the protein adsorption, platelet adhesion, complement activation, and hemolytic effect. All types of membranes show in vitro antioxidant activity and a trend to reduce oxidative stress in vivo; the best results show membranes prepared with a combination of both compounds and prove to be nonhemolytic and hemocompatible. Moreover, the membrane specific separation ability for the main waste products is not affected by antioxidants incorporation.

In Vitro Investigation of Hemocompatibility of Hydrothermally Treated Titanium and Titanium Alloy Surfaces

For decades, titanium and its alloys have been established as a biocompatible material for cardiovascular medical devices such as heart valves, stents, vascular grafts, catheters, etc. However, thrombosis is one of the reasons for implant failure, where blood clot forms on the implant surface, thus obstructing the flow of the blood and that leads to some serious complications. Various surface modification techniques such as heparin modification, albumin coating, surface anodization, plasma etching, and hydrothermal treatments have been explored to improve the hemocompatibility of titanium-based materials. However, there are several limitations related to the robustness of the surfaces and long-term efficacy in vivo. In this study, titanium and its alloy Ti-6Al-4V were hydrothermally treated to form nanostructured surfaces with the aim to enhance their hemocompatibility. These modified surfaces were characterized for their wettability, surface morphology, surface chemistry, and crystallinity. The hemocompatibility of these surfaces was characterized by evaluating blood plasma protein adsorption, platelet adhesion and activation, platelet-leukocyte complex formation, and whole blood clotting. The results indicate lower fibrinogen adsorption, cell adhesion, platelet activation, and whole blood clotting on hydrothermally treated surfaces. Thus, these surfaces may be a promising approach to prevent thrombosis for several titanium blood-contacting medical devices.

Rolling or Two-Stage Aggregation of Platelets on the Surface of Thin Ceramic Coatings under in Vitro Simulated Blood Flow Conditions

The process of modern cardiovascular device fabrication should always be associated with an investigation of how surface properties modulate its hemocompatibility through plasma protein adsorption as well as blood morphotic element activation and adhesion. In this work, a package of novel assays was used to correlate the physicochemical properties of thin ceramic coatings with hemocompatibility under dynamic conditions. Different variants of carbon-based films were prepared on polymer substrates using the magnetron sputtering method. The microstructural, mechanical, and surface physicochemical tests were performed to characterize the coatings, followed by investigation of whole human blood quality changes under blood flow conditions using the "Impact R" test, tubes' tester, and radial flow chamber assay. The applied methodology allowed us to determine that aggregate formation on hydrophobic and hydrophilic carbon-based coatings may follow one of the two different mechanisms dependent on the type and conformational changes of adsorbed blood plasma proteins.

UHMWPE-MWCNT-nHA based hybrid trilayer nanobiocomposite: Processing approach, physical properties, stem/bone cell functionality, and blood compatibility

The development of polymeric nanocomposites for biomedical applications remains a major challenge in terms of tailored addition of nanoparticles to realize the simultaneous enhancement of fracture resistance and cell/blood compatibility. To address this, the present work has been planned to determine whether small addition of surface functionalized multiwalled-carbon-nanotube, MWCNT (<1.5 wt%) and egg-shell derived nanosized hydroxyapatite, nHA (<10 wt%) to ultrahigh-molecular-weight-polyethylene (UHMWPE) can significantly improve the physical properties as well as biocompatibility. The difference in mouse osteoblast and human mesenchymal stem cell (hMSc) proliferation has been validated using both the monolithic composite and a trilayered composite with two different UHMWPE nanocomposites on either face with pure polymer at the middle. The combination of rheology and micro-CT with fractography reveals the homogeneous dispersion of nanofillers, leading to mechanical property enhancement. The quantitative analysis of cell viability and cell spreading by immunocytochemistry method, using vinculin and vimentin expression, establish significant cytocompatibility with hMSc and osteoblast cells onto the trilayer hybrid nanobiocomposite substrates. The hemocompatibility of the investigated composites under the controlled flow of rabbit blood in a microfluidic device reveals the signature of reduced thrombogenesis with reduction of platelet activation on UHMWPE nanocomposite w.r.t. unreinforced UHMWPE. An attempt has been made to discuss the blood compatibility results in the backdrop of the bovine serum albumin adsorption kinetics. Summarizing, the present study establishes that the twin requirement of mechanical property and cyto/hemo-compatibility can be potentially realized in developing trilayer composites in UHMWPE-nHA-MWCNT system.

Fabrication and Plasma Modification of Nanofibrous Tissue Engineering Scaffolds

This paper provides a comprehensive overview of nanofibrous structures for tissue engineering purposes and the role of non-thermal plasma technology (NTP) within this field. Special attention is first given to nanofiber fabrication strategies, including thermally-induced phase separation, molecular self-assembly, and electrospinning, highlighting their strengths, weaknesses, and potentials. The review then continues to discuss the biodegradable polyesters typically employed for nanofiber fabrication, while the primary focus lies on their applicability and limitations. From thereon, the reader is introduced to the concept of NTP and its application in plasma-assisted surface modification of nanofibrous scaffolds. The final part of the review discusses the available literature on NTP-modified nanofibers looking at the impact of plasma activation and polymerization treatments on nanofiber wettability, surface chemistry, cell adhesion/proliferation and protein grafting. As such, this review provides a complete introduction into NTP-modified nanofibers, while aiming to address the current unexplored potentials left within the field.

Evaluating medical device and material thrombosis under flow: current and emerging technologies

This review highlights the importance of flow in medical device thrombosis and explores current and emerging technologies to evaluate dynamic biomaterial Thrombosis in vitro.

In Vitro Thrombogenicity Testing of Biomaterials

The short- and long-term thrombogenicity of implant materials is still unpredictable, which is a significant challenge for the treatment of cardiovascular diseases. A knowledge-based approach for implementing biofunctions in materials requires a detailed understanding of the medical device in the biological system. In particular, the interplay between material and blood components/cells as well as standardized and commonly acknowledged in vitro test methods allowing a reproducible categorization of the material thrombogenicity requires further attention. Here, the status of in vitro thrombogenicity testing methods for biomaterials is reviewed, particularly taking in view the preparation of test materials and references, the selection and characterization of donors and blood samples, the prerequisites for reproducible approaches and applied test systems. Recent joint approaches in finding common standards for a reproducible testing are summarized and perspectives for a more disease oriented in vitro thrombogenicity testing are discussed.

Hemocompatibility of Super-Repellent surfaces: Current and Future

Virtually all blood-contacting medical implants and devices initiate immunological events in the form of thrombosis and inflammation. Typically, patients receiving such implants are also given large doses of anticoagulants, which pose a high risk and a high cost to the patient. Thus, the design and development of surfaces with improved hemocompatibility and reduced dependence on anticoagulation treatments is paramount for the success of blood-contacting medical implants and devices. In the past decade, the hemocompatibility of super-repellent surfaces (i.e., surfaces that are extremely repellent to liquids) has been extensively investigated because such surfaces greatly reduce the blood-material contact area, which in turn reduces the area available for protein adsorption and blood cell or platelet adhesion, thereby offering the potential for improved hemocompatibility. In this review, we critically examine the progress made in characterizing the hemocompatibility of super-repellent surfaces, identify the unresolved challenges and highlight the opportunities for future research on developing medical implants and devices with super-repellent surfaces.

Inhibition of Glycation-Induced Aggregation of Human Serum Albumin by Organic-Inorganic Hybrid Nanocomposites of Iron Oxide-Functionalized Nanocellulose

Protein aggregation leads to the transformation of proteins from their soluble form to the insoluble amyloid fibrils and these aggregates get deposited in the specific body tissues, accounting for various diseases. To prevent such an aggregation, organic-inorganic hybrid nanocomposites of iron oxide nanoparticle (NP, ∼6.5-7.0 nm)-conjugated cellulose nanocrystals (CNCs) isolated from Syzygium cumini (SC) and Pinus roxburghii (PR) were chemically synthesized. Transmission electron microscopy (TEM) images of the nanocomposites suggested that the in situ-synthesized iron oxide NPs were bound to the CNC surface in a uniform and regular fashion. The ThT fluorescence assay together with 8-anilino-1-naphthalenesulfonic acid, Congo Red, and CD studies suggested that short fiber-based SC nanocomposites showed better inhibition as well as dissociation of human serum albumin aggregates. The TEM and fluorescence microscopy studies supported similar observations. Native polyacrylamide gel electrophoresis results documented dissociation of higher protein aggregates in the presence of the developed nanocomposite. Interestingly, the dissociated proteins retained their biological function by maintaining a high amount of α-helix content. The in vitro studies with HEK-293 cells suggested that the developed nanocomposite reduces aggregation-induced cytotoxicity by intracellular reactive oxygen species scavenging and maintaining the Ca2+ ion-channel. These results indicated that the hybrid organic-inorganic nanocomposite, with simultaneous sites for hydrophobic and hydrophilic interactions, tends to provide a larger surface area for nanocomposite-protein interactions, which ultimately disfavors the nucleation step for fibrillation for protein aggregates.

Ex Vivo and In Vivo Biocompatibility Assessment (Blood and Tissue) of Three-Dimensional Bacterial Nanocellulose Biomaterials for Soft Tissue Implants

Bacterial nanocellulose (BNC) is a promising biomedical material. However, the haemocompatibility (haemolysis and thrombogenicity) and acute and sub-chronic immune responses to three-dimensional (3D) BNC biomaterials have not been evaluated. Accordingly, this manuscript focused on the effect of 3D microporosity on BNC haemocompatibility and a comparison with 2D BNC architecture, followed by the evaluation of the immune response to 3D BNC. Blood ex vivo studies indicated that compared with other 2D and 3D BNC architectures, never-dried 2D BNC presented antihemolytic and antithrombogenic effects. Nevertheless, in vivo studies indicated that 3D BNC did not interfere with wound haemostasis and elicited a mild acute inflammatory response, not a foreign body or chronic inflammatory response. Moreover, compared with the polyethylene controls, the implant design with micropores ca. 60 µm in diameter showed a high level of collagen, neovascularization and low fibrosis. Cell/tissue infiltration increased to 91% after 12 weeks and was characterized by fibroblastic, capillary and extracellular matrix infiltration. Accordingly, 3D BNC biomaterials can be considered a potential implantable biomaterial for soft tissue augmentation or replacement.

Anticoagulant Polyethylene Terephthalate Surface by Plasma-Mediated Fucoidan Immobilization

Biomaterial-based blood clot formation is one of the biggest drawbacks of blood-contacting devices. To avoid blood clot formation, their surface must be tailored to increase hemocompatibility. Most synthetic polymeric biomaterials are inert and lack bonding sites for chemical agents to bond or tailor to the surface. In this study, polyethylene terephthalate was subjected to direct current air plasma treatment to enhance its surface energy and to bring oxidative functional binding sites. Marine-sourced anticoagulant sulphated polysaccharide fucoidan from Fucus vesiculosus was then immobilized onto the treated polyethylene terephthalate (PET) surface at different pH values to optimize chemical bonding behavior and therefore anticoagulant performance. Surface properties of samples were monitored using the water contact angle; chemical analyses were performed by FTIR and X-ray photoelectron spectroscopy (XPS) and their anticoagulant activity was tested by means of prothrombin time, activated partial thromboplastin time and thrombin time. On each of the fucoidan-immobilized surfaces, anticoagulation activity was performed by extending the thrombin time threshold and their pH 5 counterpart performed the best result compared to others.

Physicochemical evaluation and in vitro hemocompatibility study on nanoporous hydroxyapatite

Hydroxyapatite is an ideal biomaterial for bone tissue engineering due to its biocompatibility and hemocompatibility which have been widely studied by many researchers. The incorporation of nanoporosity into hydroxyapatite could transform the biomaterial into an effective adsorbent for uremic toxins removal especially in artificial kidney system. However, the effect of nanoporosity incorporation on the hemocompatibility of hydroxyapatite has yet to be answered. In this study, nanoporous hydroxyapatite was synthesized using hydrothermal technique and its hemocompatibility was determined. Non-ionic surfactants were used as soft templates to create porosity in the hydroxyapatite. The presence of pure hydroxyapatite phase in the synthesized samples is validated by X-ray diffraction analysis and Fourier transform infrared spectroscopy. The TEM images show that the hydroxyapatite formed rod-like particles with the length of 21-90 nm and diameter of 11-70 nm. The hydroxyapatite samples exhibit BET surface area of 33-45 m² g^-1 and pore volume of 0.35-0.44 cm³ g^-1. The hemocompatibility of the hydroxyapatite was determined via hemolysis test, platelet adhesion, platelet activation and blood clotting time measurement. The nanoporous hydroxyapatite shows less than 5% hemolysis, suggesting that the sample is highly hemocompatible. There is no activation and morphological change observed on the platelets adhered onto the hydroxyapatite. The blood clotting time demonstrates that the blood incubated with the hydroxyapatite did not coagulate. This study summarizes that the synthesized nanoporous hydroxyapatite is a highly hemocompatible biomaterial and could potentially be utilized in biomedical applications.

The optimal incubation time for in vitro hemocompatibility testing: Assessment using polymer reference materials under pulsatile flow with physiological wall shear stress conditions

During hemocompatibility testing, activation products may reach plateau values which can result in less distinction between hemocompatible and hemo‐incompatible materials. Of concern is an underestimation of the blood activation caused by the biomaterial of interest, which may result in a false assessment of hemocompatibility. To elucidate the optimal incubation time for in vitro hemocompatibility testing, we used the Haemobile circulation model with human whole blood. Blood from healthy volunteers was in vitro incubated under pulsatile flow with physiological wall shear stress conditions at 37°C for 30, 60, 120, or 240 min. Test loops containing low‐density polyethylene and polydimethylsiloxane served as low and high reference materials, that is, hemocompatible and hemo‐incompatible biomaterials, respectively. In addition, empty loops served as a negative reference. Thrombogenicity, platelet function, inflammatory response, coagulation, and hemolysis between references and incubation times were compared. We found that thrombogenicity and platelet function were significantly affected by both the duration of incubation and the type of material. In particular, thrombogenicity and platelet function assessments were affected by incubation time. We found that an exposure time of 60 min was sufficient, and for almost all variables an optimal incubation time to discriminate between the low and high reference material. © 2019 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2335–2342, 2019.