An In Situ UV Cross-Linking Asymmetric Adhesive Hydrogel for Noncompressible Hemostasis and Postoperative Adhesion Prevention

Noncompressible hemorrhage control is vital for clinical outcome after surgical treatment and prehospital trauma injuries. Meanwhile, wound bleeding and tissue damage could induce postoperative adhesions, leading to a severe threat to the health of patients. Considerable research had been conducted on the development of hemostatic and antiadhesive materials. However, it was still a great challenge to realize hemostasis and antiadhesion simultaneously especially in inaccessible and irregular wound sites. In this study, a kind of fluid hemostatic agent composed of gelatin methacryloyl/sulfobetaine methacrylate/oxidized konjac glucomannan (termed GOS) was developed, which spread immediately upon contacting the hepatic trauma surface and turned into hydrogels under UV radiation within 5 s, resulting in rapid hemostasis and firm adhesion to tissues (shear strength 486.08 kPa). Importantly, the surface of the as-formed GOS hydrogel exhibited lubricious and nonadhesive properties, exhibiting excellent anti-postoperative adhesion performance in a rat liver hemostasis model and a rat abdominal wall-cecum adhesion model. In addition, the GOS hydrogel reduced the postoperative secretion of inflammatory factors TNF-α and IL-6, facilitating the tissue repair. Therefore, the asymmetrical adhesive GOS hydrogel could fulfill the requirements for simultaneously rapid hemostasis, tissue adhesion, and subsequent excellent antiadhesion, which demonstrated significant potential for diverse clinical surgical operation scenarios.

Advancements in textile techniques for cardiovascular tissue replacement and repair

In cardiovascular therapeutics, procedures such as heart transplants and coronary artery bypass graft are pivotal. However, an acute shortage of organ donors increases waiting times of patients, which is reflected in negative effects on the outcome for the patient. Post-procedural complications such as thrombotic events and atherosclerotic developments may also have grave clinical implications. To address these challenges, tissue engineering is emerging as a solution, using textile technologies to synthesize biomimetic scaffolds resembling natural tissues. This comprehensive analysis explains methodologies including electrospinning, electrostatic flocking, and advanced textile techniques developed from weaving, knitting, and braiding. These techniques are evaluated in the context of fabricating cardiac patches, vascular graft constructs, stent designs, and state-of-the-art wearable sensors. We also closely examine the interaction of distinct process parameters with the biomechanical and morphological attributes of the resultant scaffolds. The research concludes by combining current findings and recommendations for subsequent investigation.

Creation of Grooved Tissue Engineering Scaffolds from Architectured Multilayer Polymer Composites by a Tuneable One-Step Degradation Process

The surface properties of biomaterials interact directly with biological systems, influencing cellular responses, tissue integration, and biocompatibility. Surface topography plays a critical role in cardiac tissue engineering by affecting electrical conductivity, cardiomyocyte alignment, and contractile function. Current methods for controlling surface properties and topography in cardiac tissue engineering scaffolds are limited, expensive, and lack precision. This study introduces a low-cost, one-step degradation process to create scaffolds with well-defined micro-grooves from multilayered 3D printed poly(lactic acid)/thermoplastic polyurethane composites. The approach provides control over erosion rate and surface morphology, allowing easy tuning of scaffold topographical cues for tissue engineering applications. The findings reported in this study provide a library of easily tuneable scaffold topographical cues. A strong dependence of neonatal rat cardiomyocyte (NRCM) contact guidance with the multilayers' dimension and shape in partially degraded polylactic acid (PLA)/thermoplastic polyurethane (TPU) samples is observed. NRCMs cultured on samples with a layer thickness of 13 ± 2 µm and depth of 4.7 ± 0.2 µm demonstrate the most regular contractions. Hence, the proposed fabrication scheme can be used to produce a new generation of biomaterials with excellent controllability determined by multilayer thickness, printing parameters, and degradation treatment duration.

The Synergetic Effect of 3D Printing and Electrospinning Techniques in the Fabrication of Bone Scaffolds

The primary goal of bone tissue engineering is to restore and rejuvenate bone defects by using a suitable three-dimensional scaffold, appropriate cells, and growth hormones. Various scaffolding methods are used to fabricate three-dimensional scaffolds, which provide the necessary environment for cell activity and bone formation. Multiple materials may be used to create scaffolds with hierarchical structures that are optimal for cell growth and specialization. This study examines a notion for creating an optimal framework for bone regeneration using a combination of the robocasting method and the electrospinning approach. Research indicates that the integration of these two procedures enhances the benefits of each method and provides a rationale for addressing their shortcomings via this combination. The hybrid approach is anticipated to provide a manufactured scaffold that can effectively replace bone defects while possessing the necessary qualities for bone regeneration.

Photobiomodulation and Vascularization in Conduit-Based Peripheral Nerve Repair: A Narrative Review

Background: Peripheral nerve injuries pose a significant clinical issue for patients, especially in the most severe cases wherein complete transection (neurotmesis) results in total loss of sensory/motor function. Nerve guidance conduits (NGCs) are a common treatment option that protects and guides regenerating axons during recovery. However, treatment outcomes remain limited and often fail to achieve full reinnervation, especially in critically sized defects (>3 cm) where a lack of vascularization leads to neural necrosis. Conclusions: A multitreatment approach is, therefore, necessary to improve the efficacy of NGCs. Stimulating angiogenesis within NGCs can help alleviate oxygen deficiency through rapid inosculation with the host vasculature, whereas photobiomodulation therapy (PBMT) has demonstrated beneficial therapeutic effects on regenerating nerve cells and neovascularization. In this review, we discuss the current trends of NGCs, vascularization, and PBMT as treatments for peripheral nerve neurotmesis and highlight the need for a combinatorial approach to improve functional and clinical outcomes.

Bioactive materials for in vivo sweat gland regeneration

Loss of sweat glands (SwGs) commonly associated with extensive skin defects is a leading cause of hyperthermia and heat stroke. In vivo tissue engineering possesses the potential to take use of the body natural ability to regenerate SwGs, making it more conducive to clinical translation. Despite recent advances in regenerative medicine, reconstructing SwG tissue with the same structure and function as native tissue remains challenging. Elucidating the SwG generation mechanism and developing biomaterials for in vivo tissue engineering is essential for understanding and developing in vivo SwG regenerative strategies. Here, we outline the cell biology associated with functional wound healing and the characteristics of bioactive materials. We critically summarize the recent progress in bioactive material-based cell modulation approaches for in vivo SwG regeneration, including the recruitment of endogenous cells to the skin lesion for SwG regeneration and in vivo cellular reprogramming for SwG regeneration. We discussed the re-establishment of microenvironment via bioactive material-mediated regulators. Besides, we offer promising perspectives for directing in situ SwG regeneration via bioactive material-based cell-free strategy, which is a simple and effective approach to regenerate SwG tissue with both fidelity of structure and function. Finally, we discuss the opportunities and challenges of in vivo SwG regeneration in detail. The molecular mechanisms and cell fate modulation of in vivo SwG regeneration will provide further insights into the regeneration of patient-specific SwGs and the development of potential intervention strategies for gland-derived diseases.

A drug-incorporated-microparticle-eggshell-membrane-scaffold (DIMES) dressing: A novel biomaterial for localised wound regeneration

Chronic wounds affect millions of people annually and have emotional and financial implications in addition to health issues. The current treatment for chronic wounds involves the repeated use of bandages and drugs such as antibiotics over an extended period. A cost-effective and convenient solution for wound healing is the development of drug-incorporated bandages. This study aimed to develop a biocompatible bandage made of drug-incorporated poly (lactic-co-glycolic acid) (PLGA) microparticles (MPs) and eggshell membrane (ESM) for cornea wound healing. ESM has desirable properties for wound healing and can be isolated from eggshells using acetic acid or ethylenediaminetetraacetic acid (EDTA) protocols. Fluorescein isothiocyanate-labelled Bovine Serum Albumin (FITC-BSA) was used as a model drug, and the PLGA MPs were fabricated using a solvent extraction method. The MPs were successfully attached to the fibrous layer of the ESM using NaOH. The surface features of the ESM samples containing MPs were studied using a field emission scanning electron microscope (FESEM) and compared with blank ESM images. The findings indicated that the MPs were attached to the ESM fibres and had similar shapes and sizes as the control MPs. The fibre diameters of the MPs samples were assessed using Fiji-ImageJ software, and no significant changes were observed compared to the blank ESM. The surface roughness, Ra values, of the MPs incorporated ESM samples were evaluated and compared to the blank ESM, and no significant changes were found. Fourier transform infrared (FTIR) spectroscopy was used to analyse the chemical Composition of the bandage, and the spectra showed that the FBM were effectively incorporated into the ESM. The FTIR spectra identified the major peaks of the natural ESM and the PLGA polymer in the bandage. The bandage was transparent but had a reduced visibility in the waterproof test card method. The bandage achieved sustained drug release up to 10 days and was found to be biocompatible and non-toxic in a chorioallantoic membrane (CAM) assay. Overall, the drug-incorporated PLGA MPs-ESM bandage has great potential for treating chronic wounds.

Bioactive inorganic nanomaterials for cancer theranostics

Bioactive materials are a special class of biomaterials that can react in vivo to induce a biological response or regulate biological functions, thus achieving a better curative effect than traditional inert biomaterials. For cancer theranostics, compared with organic or polymer nanomaterials, inorganic nanomaterials possess unique physical and chemical properties, have stronger mechanical stability on the basis of maintaining certain bioactivity, and are easy to be compounded with various carriers (polymer carriers, biological carriers, etc.), so as to achieve specific antitumor efficacy. After entering the nanoscale, due to the nano-size effect, high specific surface area and special nanostructures, inorganic nanomaterials exhibit unique biological effects, which significantly influence the interaction with biological organisms. Therefore, the research and applications of bioactive inorganic nanomaterials in cancer theranostics have attracted wide attention. In this review, we mainly summarize the recent progress of bioactive inorganic nanomaterials in cancer theranostics, and also introduce the definition, synthesis and modification strategies of bioactive inorganic nanomaterials. Thereafter, the applications of bioactive inorganic nanomaterials in tumor imaging and antitumor therapy, including tumor microenvironment (TME) regulation, catalytic therapy, gas therapy, regulatory cell death and immunotherapy, are discussed. Finally, the biosafety and challenges of bioactive inorganic nanomaterials are also mentioned, and their future development opportunities are prospected. This review highlights the bioapplication of bioactive inorganic nanomaterials.

Surface Functionalities of Polymers for Biomaterial Applications

Changes of a material biointerface allow for specialized cell signaling and diverse biological responses. Biomaterials incorporating immobilized bioactive ligands have been widely introduced and used for tissue engineering and regenerative medicine applications in order to develop biomaterials with improved functionality. Furthermore, a variety of physical and chemical techniques have been utilized to improve biomaterial functionality, particularly at the material interface. At the interface level, the interactions between materials and cells are described. The importance of surface features in cell function is then examined, with new strategies for surface modification being highlighted in detail.

Promises of Functionally Graded Material in Bone Regeneration: Current Trends, Properties, and Challenges

Functionally graded materials (FGMs) are emerging materials systems, with structures and compositions gradually changing in a particular direction. Consequently, the properties of the materials gradually change in the desired direction to achieve particular nonhomogeneous service demands without abrupting the compositional and behavioral interface at the macroscale. FGMs have been found to have high potential as orthopedic implants; because the functional gradient can be adapted in such a manner that the core of FGM should be compatible with the density and strength of bone, interlayers can maintain the structural integrity and outermost layers would provide bioactivity and corrosion resistance, thus overall tailoring the stress shielding effect. This review article discusses the typical FGM systems existing in nature and the human body, focusing on bone tissue. Further, the reason behind the application of these FGMs systems in orthopedic implants is explored in detail, considering the physical and biological necessities. The substantial focus of the present critical review is devoted to two primary topics related to the usage of FGMs for orthopedic implants: (1) the synthesizing techniques currently available to produce FGMs for load-bearing orthopedic applications and (2) the properties, such as mechanical, structural, and biological behavior of the FGMs. This review article gives an insight into the potential of FGMs for orthopedic applications.

Surface Modification of Additively Manufactured Nitinol by Wet Chemical Etching

Three-dimensional printed nitinol (NiTi) alloys have broad prospects for application in medicine due to their unique mechanical properties (shape memory effect and superplasticity) and the possibilities of additive technologies. However, in addition to mechanical properties, specific physicochemical characteristics of the surface are necessary for successful medical applications. In this work, a comparative study of additively manufactured (AM) NiTi samples etched in H2SO4/H2O2, HCl/H2SO4, and NH4OH/H2O2 mixtures was performed. The morphology, topography, wettability, free surface energy, and chemical composition of the surface were studied in detail. It was found that etching in H2SO4/H2O2 practically does not change the surface morphology, while HCl/H2SO4 treatment leads to the formation of a developed morphology and topography. In addition, exposure of nitinol to H2SO4/H2O2 and HCl/H2SO4 contaminated its surface with sulfur and made the surface wettability unstable in air. Etching in NH4OH/H2O2 results in surface cracking and formation of flat plates (10-20 microns) due to the dissolution of titanium, but clearly increases the hydrophilicity of the surface (values of water contact angles are 32-58°). The etch duration (30 min or 120 min) significantly affects the morphology, topography, wettability and free surface energy for the HCl/H2SO4 and NH4OH/H2O2 etched samples, but has almost no effect on surface composition.

Advanced bioactive nanomaterials for biomedical applications

Bioactive materials are a kind of materials with unique bioactivities, which can change the cellular behaviors and elicit biological responses from living tissues. Bioactive materials came into the spotlight in the late 1960s when the researchers found that the materials such as bioglass could react with surrounding bone tissue for bone regeneration. In the following decades, advances in nanotechnology brought the new development opportunities to bioactive nanomaterials. Bioactive nanomaterials are not a simple miniaturization of macroscopic materials. They exhibit unique bioactivities due to their nanoscale size effect, high specific surface area, and precise nanostructure, which can significantly influence the interactions with biological systems. Nowadays, bioactive nanomaterials have represented an important and exciting area of research. Current and future applications ensure that bioactive nanomaterials have a high academic and clinical importance. This review summaries the recent advances in the field of bioactive nanomaterials, and evaluate the influence factors of bioactivities. Then, a range of bioactive nanomaterials and their potential biomedical applications are discussed. Furthermore, the limitations, challenges, and future opportunities of bioactive nanomaterials are also discussed.

Modification of the surface nanotopography of implant devices: A translational perspective

There is an increasing need for the development of superior, safe, and more sophisticated implants, especially as our society historically has been moving towards an increasingly aging population. Currently, most research is being focused on the next generation of advanced medical implants, that are not only biocompatible but have modified surfaces that direct specific immunomodulation at cellular level. While there is a plethora of information on cell-surface interaction and how surfaces can be nanofabricated at research level, less is known about how the academic knowledge has been translated into clinical trials and commercial technologies. In this review, we provide a clinical translational perspective on the use of controlled physical surface modification of medical implants, presenting an analysis of data acquired from clinical trials and commercial products. We also evaluate the state-of-the-art of nanofabrication techniques that are being applied for implant surface modification at a clinical level. Finally, we identify some current challenges in the field, including the need of more advanced nanopatterning techniques, the comparatively small number of clinical trials and comment on future avenues to be explored for a successful clinical translation.

In-Situ One-Step Direct Loading of Agents in Poly(acrylic acid) Coating Deposited by Aerosol-Assisted Open-Air Plasma

In biomaterials and biotechnology, coatings loaded with bioactive agents are used to trigger biological responses by acting as drug release platforms and modulating surface properties. In this work, direct deposition of poly(acrylic acid) coatings containing various agents, such as dyes, fluorescent molecules, was achieved by aerosol-assisted open-air plasma. Using an original precursors injection strategy, an acrylic acid aerosol was loaded with an aqueous aerosol and deposited on silicon wafers. Results clearly showed that agents dissolved in the aqueous aerosol were successfully entrapped in the final coating. The effect of aerosols concentration, flow rate, and treatment time, on the coating morphology and the amount of entrapped agents, was also investigated. It was demonstrated that this process has the potential to entrap a tunable amount of any sensible water-soluble agent without altering its activity. To the best of our knowledge, this is the first time that the loading of an aqueous aerosol in coatings deposited by plasma from a liquid aerosol precursor is reported. This innovative approach complements plasma deposition of coatings loaded with bioactive agents from aqueous aerosols with the use of non-volatile liquid precursors.

Blood biocompatibility enhancement of biomaterials by heparin immobilization: a review

Blood contacting materials are concerned with biocompatibility including thrombus formation, decrease blood coagulation time, hematology, activation of complement system, platelet aggression. Interestingly, recent research suggests that biocompatibility is increasing by incorporating various materials including heparin using different methods. Basic of heparin including uses and complications was mentioned, in which burst release of heparin is major issue. To minimize the problem of biocompatibility and unpredictable heparin release, present review article potentially reviews the reported work and investigates the various immobilization methods of heparin onto biomaterials, such as polymers, metals, and alloys. Detailed explanation of different immobilization methods through different intermediates, activation, incubation method, plasma treatment, irradiations and other methods are also discussed, in which immobilization through intermediates is the most exploitable method. In addition to biocompatibility, other required properties of biomaterials like mechanical and corrosion resistance properties that increase by attachment of heparin are reviewed and discussed in this article.

Osteogenesis Promotion of Selenium-Doped Hydroxyapatite for Application as Bone Scaffold

The combined bioceramic of selenium (Se) and hydroxyapatite (HA) has been considered as a moderate bone scaffold biomaterial. In the present work, Se was doped into the HA structure using the mechano-chemical alloying (MCA) method for the improvement of osteogenic properties of HA. HA extracted from fish bone and Se-doped hydroxyapatite (Se-HA) were analyzed using X-ray diffraction spectra (XRD), scanning electron microscope (SEM), energy dispersion X-ray spectrometer (EDX), and Fourier transform infrared spectroscopy (FT-IR). In-vitro cell responses on the Se-HA bioceramic scaffold were investigated using human adipose-derived mesenchymal stem cells (hAD-MSCs). The effect of Se on cell proliferation was studied by MTT assay, and cell adhesion responses were analyzed by optical microscopy and SEM. Furthermore, the effect of Se on osteogenic properties of HA was studied by alkaline phosphatase (ALP) activity, alizarin red S (ARS) staining, and Western blot tests. The MTT results showed that the Se dopant synergistically increases the proliferation of hAD-MSCs. Moreover, good cell-adhesive and osteoblast-shaped behaviors were observed on the Se-HA scaffold. The results of osteogenic differentiation demonstrated synergistically enhanced ALP activity and calcification on the Se dopant compared to HA. Also, the results of Western blot test presented that the differentiation of hAD-MSCs toward being a bone tissue was increased by up to 50% while selenium doping. Additional MTT analysis using Human Bone Osteosarcoma cell line (KHOS-240S) revealed the antiproliferative activity of the Se-HA scaffold against bone cancerous cells. Therefore, it has been concluded that Se-HA bioceramic can be employed as a scaffold with simultaneous anticancer and bone regenerative properties.

Fibronectin grafting to enhance skin sealing around transcutaneous titanium implant

Intraosseous transcutaneous amputation prosthesis is a new approach in orthopedic implants that overcomes socket prosthesis problems. Its long-term performance requires a tight skin-implant seal to prevent infections. In this study, fibronectin (Fn), a widely used adhesion protein, was adsorbed or grafted onto titanium alloy. Fn grafting was performed using two different linking arms, dopamine/glutaric anhydride or phosphonate. The characterization of Fn-modified surfaces showed that Fn grating via phosphonate has led to the highest amount of Fn cell-binding site (RGD, arginine, glycine, and aspartate) available on the surface. Interestingly, cell culture studies revealed a strong correlation between the amount of available RGD ligands and cellular behavior, since enhanced proliferation and spreading of fibroblasts were noticed on Fn-grafted surfaces via phosphonate. In addition, an original in vitro mechanical test, inspired from the real situation, to better predict clinical outcomes after implant insertion, has been developed. Tensile test data showed that the adhesion strength of a bio-engineered dermal tissue was significantly higher around Fn-grafted surfaces via phosphonate, as compared to untreated surfaces. This study sheds light on the importance of an appropriate selection of the linking arm to tightly control the spatial conformation of biomolecules on the material surface, and consequently cell interactions at the interface tissue/implant.

Fibronectin-Functionalized Fibrous Meshes as a Substrate to Support Cultures of Thymic Epithelial Cells

Thymic epithelial cells (TECs) are the main regulators of T lymphocyte development and selection, requiring a three-dimensional (3D) environment to properly perform these biological functions. The aim of this work was to develop a 3D culture substrate that allows the survival and proliferation of TECs. Thus, electrospun fibrous meshes (eFMs) were functionalized with fibronectin, one of the major extracellular matrix (ECM) proteins of the thymus. For that, highly porous eFMs were activated using oxygen plasma treatment followed by amine insertion, which allows the immobilization of fibronectin through EDC/NHS chemistry. The medullary TECs presented increased proliferation, viability, and protein synthesis when cultured on fibronectin-functionalized eFMs (FN-eFMs). These cells showed a spread morphology, with increased migration toward the inner layers of FN-eFMs and the production of thymic ECM proteins, such as collagen type IV and laminin. These results suggest that FN-eFMs are an effective substrate for supporting thymic cell cultures.

3D printing in pharmaceuticals: An emerging technology full of challenges

Although in its infancy, when compared with the other sectors, year 2005 marked the rapid evolution of 3 Dimensional printing (3DP) technologies in pharma sector with a huge potential in the dosage form designing and personalisation of the medication. 3DP is an innovative and highly promising way for the instant manufacturing in contrast with the tailored made conventional manufacturing. Various 3DP technologies are categorized into the various areas on the basis of the type of material used, deposition techniques and the solidification/fusion techniques. 3DP technologies have multiple pharmaceutical applications including formulation of the precise and unique dosage forms, medical research, personalization of medicine, tissues engineering and surgical application. In the present article, we have accentuated the comparative merits and demerits of various 3DP technologies used in the pharmaceutical sector. An insight in to the challenges, apropos availability and the choice of the excipients, as well as the printer, regulatory and safety concern of the product is provided.

Plasma polymerised nanoscale coatings of controlled thickness for efficient solid-phase presentation of growth factors

The engineering of biomaterial surfaces and scaffolds for specific biomedical and clinical application is of growing interest. Certain functionalised surfaces can capture and deliver bioactive molecules, such as growth factors (GF), enhancing the clinical efficacy of such systems. With a custom-made plasma polymerisation reactor described here we have developed bioactive polymer coatings based on poly(ethyl acrylate) (PEA). This remarkable polymer unfolds fibronectin (FN) upon adsorption to allow the GF binding region of FN to sequester and present GFs with high efficiency. We systematically evaluate process conditions and their impact on plasma polymerised PEA coatings and characterise the effect of plasma power and deposition time on thickness, wettability and chemical composition of the coatings. We demonstrate that functional substrate roughness can be maintained after deposition of the polymer coatings. Importantly, we show that coatings deposited at different conditions all maintain a similar or better bioactivity than spin coated PEA references. We show that in PEA plasma polymerised coatings FN assembles into nanonetworks with high availability of integrin and GF binding regions that sequester bone morphogenetic protein-2 (BMP-2). We also report similar mesenchymal stem cell adhesion behaviour, as characterised by focal adhesions, and differentiation potential on BMP-2 coated surfaces, regardless of plasma deposition conditions. This is a potent and versatile technology that can help facilitate the use of GFs in clinical applications.

Non-equilibrium organosilane plasma polymerization for modulating the surface of PTFE towards potential blood contact applications

We report a novel and facile organosilane plasma polymerization method designed to improve the surface characteristics of poly(tetrafluoroethylene) (PTFE). We hypothesized that the polymerized silane coating would provide an adhesive surface for endothelial cell proliferation due to a large number of surface hydroxyl groups, while the large polymer networks on the surface of PTFE would hinder platelet attachment. The plasma polymerized PTFE surfaces were then systematically characterized via different analytical techniques such as FTIR, XPS, XRD, Contact angle, and SEM. The key finding of the characterization is the time-dependent deposition of an organosilane layer on the surface of PTFE. This layer was found to provide favorable surface properties to PTFE such as a very high surface oxygen content, high hydrophilicity and improved surface mechanics. Additionally, in vitro cellular studies were conducted to determine the bio-interface properties of the plasma-treated and untreated PTFE. The important results of these experiments were rapid endothelial cell growth and decreased platelet attachment on the plasma-treated PTFE compared to untreated PTFE. Thus, this new surface modification technique could potentially address the current challenges associated with PTFE for blood contact applications, specifically poor endothelial cell growth and risk of thrombosis.

Proteins and Peptides as Important Modifiers of the Polymer Scaffolds for Tissue Engineering Applications-A Review

Polymer scaffolds constitute a very interesting strategy for tissue engineering. Even though they are generally non-toxic, in some cases, they may not provide suitable support for cell adhesion, proliferation, and differentiation, which decelerates tissue regeneration. To improve biological properties, scaffolds are frequently enriched with bioactive molecules, inter alia extracellular matrix proteins, adhesive peptides, growth factors, hormones, and cytokines. Although there are many papers describing synthesis and properties of polymer scaffolds enriched with proteins or peptides, few reviews comprehensively summarize these bioactive molecules. Thus, this review presents the current knowledge about the most important proteins and peptides used for modification of polymer scaffolds for tissue engineering. This paper also describes the influence of addition of proteins and peptides on physicochemical, mechanical, and biological properties of polymer scaffolds. Moreover, this article sums up the major applications of some biodegradable natural and synthetic polymer scaffolds modified with proteins and peptides, which have been developed within the past five years.

Biocompatibility Evaluation and Enhancement of Elastomeric Coatings Made Using Table-Top Optical 3D Printer

In this experimental report, the biocompatibility of elastomeric scaffold structures made via stereolithography employing table-top 3D printer Ember (Autodesk) and commercial resin FormLabs Flexible (FormLabs) was studied. The samples were manufactured using the standard printing and development protocol, which is known to inherit cytotoxicity due to remaining non-polymerized monomers, despite the polymerized material being fully biocompatible. Additional steps were taken to remedy this problem: the fabricated structures were soaked in isopropanol and methanol under different conditions (temperature and duration) to leach out the non-polymerized monomers. In addition, disc-shaped 3D-printed structures were UV exposed to assure maximum polymerization degree of the material. Post-processed structures were seeded with myogenic stem cells and the number of live cells was evaluated as an indicator for the material biocompatibility. The straightforward post-processing protocol enhanced the biocompatibility of the surfaces by seven times after seven days soaking in isopropanol and methanol and was comparable to control (glass and polystyrene) samples. This proposes the approach as a novel and simple method to be widely applicable for dramatic cytotoxicity reduction of optically 3D printed micro/nano-scaffolds for a wide range of biomedical studies and applications.

Tailoring Surface Hydrophilicity Property for Biomedical 316L and 304 Stainless Steels: A Special Perspective on Studying Osteoconductivity and Biocompatibility

Stainless steels used as metal implants in the medical field have been attracting intensive attention due to their advantages in mechanical properties, anticorrosion properties, and cost effectiveness. Good osteoconductivity, low toxicity, and low inflammatory reactions are essential to stainless steel implant in vivo. However, there are few cases about the surface modification performed for enhancing the corrosion resistance, and there are few researches on the relationship between the surface properties of stainless steel and osteoconductivity when used as implants. This study employed 316L and 304 stainless steel for surface modification including hydrothermal treatment after acid immersion and anodizing treatment, while the as-polished stainless steel was used as a control group. Anticorrosion properties, protein adsorption properties, osteoconductivity, and anti-inflammation property of these specimens were intensively investigated in vitro and in vivo. It was found that specimen subjected to hydrothermal treatment at 230 °C after immersion in 18 M H₂SO₄ had the lowest metal ions release, while the anodized specimen had the highest release of Fe and Cr due to corrosion. The protein adsorption amount of the specimens was positively related to the osteoconductivity, suggesting protein adsorption is the prerequisite for good osteoconductivity. The osteoconductivity decreased first and then increased with the increase in water contact angle (WCA) value. The specimen with the surface modified by hydrothermal treatment after acid immersion had the highest protein adsorption amount and the best osteoconductivity due to its superhydrophilicity property. The protein adsorption capacity and osteoconductivity for stainless steel tended to be the same as Ti alloys studied before, indicating the surface hydrophilicity property of the implanted metals was the dominant factor affecting the osteoconductivity. From an anti-inflammation perspective, the specimen with the surface modified by hydrothermal treatment after acid immersion also exhibited the lowest thickness of the fibrous capsule membrane from the in vivo tests, suggesting its advantageous biocompatibility. Thus, this research can provide new insight into the application of austenitic stainless steel for implanted material purposes.

Comparison of the linking arm effect on the biological performance of a CD31 agonist directly grafted on L605 CoCr alloy by a plasma-based multistep strategy

Stents are cardiovascular implants deployed on atherosclerotic arteries that aid in reopening, sustaining, and avoiding their collapse. Nevertheless, postimplantation complications exist, and the risk of the renewal of the plaque subsists. Therefore, enhanced properties are mandatory requirements for clinics. For that purpose, a novel approach allowing the direct-grafting of bioactive molecules on cobalt-chromium devices (L605) has been developed. This original strategy involves the direct plasma functionalization of metallic surfaces with primary amines (-NH₂). These groups act as anchor points to covalently graft biomolecules of interest, herein a peptide derived from CD31 (P23) with proendothelialization and antithrombotic properties. However, the biological activity of the grafted peptide could be impacted by its conformation. For this study, glutaric anhydride (GA), a short chain spacer, and polyethylene glycol (PEG) with antifouling properties were used as linking arms (LAs). The covalent grafting of the CD31 agonist on L605 by different LAs (GA-P23 and PEG-P23) was confirmed by XPS and ToF-SIMS analyses. The biological performance of these functionalized surfaces showed that, compared to the electropolished (EP) alloy, grafting the P23 with both LA increases adhesion and proliferation of endothelial cells (ECs) since day 1: EP = 68 ± 10%, GA-P23 = 101 ± 7%, and PEG-P23 = 106 ± 5% of cell viability. Moreover, ECs formed a complete monolayer at the surface, preventing clot formation (hemoglobin-free >80%). The potential of this plasma-based strategy for cardiovascular applications was confirmed by promoting a fast re-endothelialization, by improving the hemocompatibility of the alloy when coupled with the CD31 agonist and by its transfer onto commercial L605 stents, as confirmed by ToF-SIMS.

Characterization of Mechanical Stability and Immunological Compatibility for Functionalized Modification Interfaces

Surface modification layers are performed on the surfaces of biomaterials and have exhibited promise for decoupling original surface properties from bulk materials and enabling customized and advanced functional properties. The physical stability and the biological compatibility of these modified layers are equally important to ensure minimized delamination, debris, leaching of molecules, and other problems that are related to the failure of the modification layers and thus can provide a long-term success for the uses of these modified layers. A proven surface modification tool of the functionalized poly-para-xylylene (PPX) system was used as an example, and in addition to the demonstration of their chemical conjugation capabilities and the functional properties that have been well-documented, in the present report, we additionally devised the characterization protocols to examine stability properties, including thermostability and adhesive strength, as well as the biocompatibility, including cell viability and the immunological responses, for the modified PPX layers. The results suggested a durable coating stability for PPXs and firmly attached biomolecules under these stability and compatibility tests. The durable and stable modification layers accompanied by the native properties of the PPXs showed high cell viability against fibroblast cells and macrophages (MΦs), and the resulting immunological activities created by the MΦs exhibited excellent compatibility with non-activated immunological responses and no indication of inflammation.

Biomedical Grade Stainless Steel Coating of Polycaffeic Acid via Combined Oxidative and Ultraviolet Light-Assisted Polymerization Process for Bioactive Implant Application

Stainless steel as a biomedical implant material has been studied in various fields and in various forms, such as vascular stents, bone plates, dental screws, and artificial hip and bone material. In this study, we used polycaffeic acid (PCA), a natural phenolic compound, to coat the surface of medical grade stainless steel to provide added potential medicinal effects by virtue of its inherent anti-inflammatory, antiviral, antifibrosis, antithrombosis, and antihypertensive characteristics. We did this via UV irradiation under an alkaline state to solve the cost and time problems of other existing coating methods. The physicochemical properties of the samples were investigated through field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), contact angle, FTIR, and X-ray photoelectron spectroscopy (XPS). Surface bioactivity using NIH-3T3 cell lines were observed in vitro. We expect that the proposed methodology may contribute to the field of study of implantable metallic devices.

Surface modification and direct plasma amination of L605 CoCr alloys: on the optimization of the oxide layer for application in cardiovascular implants

Stents are cardiovascular devices used to treat atherosclerosis, and are deployed into narrowed arteries and implanted by expansion to reopen the biological lumen. Nevertheless, complications after implantation are still observed in 10-14% of the implantations. Therefore, functionalizing these devices with active molecules to improve the interfacial effects with the surrounding tissue strongly impacts their success. A plasma-based procedure to directly graft biomolecules to the surface of cobalt chromium alloys, without any polymeric coating, has been recently reported. Assuring the stability of the coating during plastic deformation generated during the implantation whilst avoiding the corrosion of the surface is crucial. This study explores different surface treatments to be used as a pre-treatment for this novel procedure. The effects of (i) electropolishing, (ii) thermal treatments, and (iii) the plasma immersion ion implantation of oxygen on the chemical composition, roughness, wettability and efficiency during the plasma-amination procedure whilst avoiding cracks after deformation, thus maintaining corrosion resistant behaviour, were investigated by XPS, AFM, ToF-SIMS imaging and depth profile, and WCA. Furthermore, the hemocompatibility of the surface and cell viability assays were also performed. Results showed that all of the treatments created a different surface chemical composition: EP mainly of chromium oxide, PIII with a layer of cobalt oxide and TT with a mixture of oxides, as observed by XPS and ToF-SIMS. Moreover, EP was the process that generated a surface with the highest efficiency to amination and the most corrosion resistance among the treatments, and it appeared as the most suitable pre-treatment for stent functionalization.

Materials Functionalization with Multicomponent Reactions: State of the Art

The emergence of neoteric synthetic routes for materials functionalization is an interesting phenomenon in materials chemistry. In particular, the union of materials chemistry with multicomponent reactions (MCRs) opens a new avenue leading to the realm of highly innovative functionalized architectures with unique features. MCRs have recently been recognized as considerable part of the synthetic chemist's toolbox due to their great efficiency, inherent molecular diversity, atom and pot economy along with operational simplicity. Also, MCRs can improve E-factor and mass intensity as important green chemistry metrics. By rational tuning of the materials, as well as the MCRs, wide ranges of functionalized materials can be produced with tailorable properties that can play important roles in the plethora of applications. To date, there has not reported any exclusive review of a materials functionalization with MCRs. This critical review highlights the state-of-the-art on the one-pot functionalization of carbonaceous and siliceous materials, polysaccharides, proteins, enzymes, synthetic polymers, etc., via diverse kind of MCRs like Ugi, Passerini, Petasis, Khabachnik-Fields, Biginelli, and MALI reactions through covalent or noncovalent manners. Besides the complementary discussion of synthetic routes, superior properties and detailed applicability of each functionalized material in modern technologies are discussed. Our outlook also emphasizes future strategies for this unprecedented area and their use as materials for industrial implementation. With no doubt, MCRs-functionalization of materials bridges the gap between materials science domain and applied chemistry.

Hyperspectral chemical imaging reveals spatially varied degradation of polycarbonate urethane (PCU) biomaterials

Hyperspectral chemical imaging (HCI) is an emerging technique which combines spectroscopy with imaging. Unlike traditional point spectroscopy, which is used in the majority of polymer biomaterial degradation studies, HCI enables the acquisition of spatially localised spectra across the surface of a material in an objective manner. Here, we demonstrate that attenuated total reflectance Fourier transform infra-red (ATR-FTIR) HCI reveals spatial variation in the degradation of implantable polycarbonate urethane (PCU) biomaterials. It is also shown that HCI can detect possible defects in biomaterial formulation or specimen production; these spatially resolved images reveal regional or scattered spatial heterogeneity. Further, we demonstrate a map sampling method, which can be used in time-sensitive scenarios, allowing for the investigation of degradation across a larger component or component area. Unlike imaging, mapping does not produce a contiguous image, yet grants an insight into the spatial heterogeneity of the biomaterial across a larger area. These novel applications of HCI demonstrate its ability to assist in the detection of defective manufacturing components and lead to a deeper understanding of how a biomaterial's chemical structure changes due to implantation.

STATEMENT OF SIGNIFICANCE

The human body is an aggressive environment for implantable devices and their biomaterial components. Polycarbonate urethane (PCU) biomaterials in particular were investigated in this study. Traditionally one or a few points on the PCU surface are analysed using ATR-FTIR spectroscopy. However the selection of acquisition points is susceptible to operator bias and critical information can be lost. This study utilises hyperspectral chemical imaging (HCI) to demonstrate that the degradation of a biomaterial varies spatially. Further, HCI revealed spatial variations of biomaterials that were not subjected to oxidative degradation leading to the possibility of HCI being used in the assessment of biomaterial formulation and/or component production.

Recent Advances in Biomaterials for 3D Printing and Tissue Engineering

Three-dimensional printing has significant potential as a fabrication method in creating scaffolds for tissue engineering. The applications of 3D printing in the field of regenerative medicine and tissue engineering are limited by the variety of biomaterials that can be used in this technology. Many researchers have developed novel biomaterials and compositions to enable their use in 3D printing methods. The advantages of fabricating scaffolds using 3D printing are numerous, including the ability to create complex geometries, porosities, co-culture of multiple cells, and incorporate growth factors. In this review, recently-developed biomaterials for different tissues are discussed. Biomaterials used in 3D printing are categorized into ceramics, polymers, and composites. Due to the nature of 3D printing methods, most of the ceramics are combined with polymers to enhance their printability. Polymer-based biomaterials are 3D printed mostly using extrusion-based printing and have a broader range of applications in regenerative medicine. The goal of tissue engineering is to fabricate functional and viable organs and, to achieve this, multiple biomaterials and fabrication methods need to be researched.

Hydroxyapatite synthesis from a starfish and β-tricalcium phosphate using a hydrothermal method

Hydroxyapatite HAp, Ca₁₀(PO₄)₆(OH)₂, was successfully synthesized using a hydrothermal method using β-tricalcium phosphate (β-TCP) and CaO from the starfish Mellita eduardobarrosoi sp. nov.

Evolution of the in vitro degradation of Zn–Mg alloys under simulated physiological conditions

Primary reactions occurring upon Zn-derived materials insertion inside an organism are of utmost importance as chemical species resulting from the degradation of resorbable biomaterials are crucial for the interaction with the surrounding tissues.

Development of novel biocompatible hybrid nanocomposites based on polyurethane-silica prepared by sol gel process

Due to high biocompatibility, polyurethane has found many applications, particularly in development of biomedical devices. A new nanocomposite based on thermoset polyurethane and silica nanoparticles was synthesized using sol-gel method. Sol-gel process was fulfilled in two acidic and basic conditions by using tetraethylorthosilicate (TEOS) and trimethoxyisocyanatesilane as precursors. The hybrid films characterized for mechanical and surface properties using tensile strength, contact angle, ATR-FTIR and scanning electron microscopy. Biocompatibility and cytotoxicity of the hybrids were assessed using standard MTT, LDH and TUNEL assays. The results revealed that incorporation of silica nanoparticles was significantly improved tensile strength and mechanical properties of the hybrids. Based on the contact angle results, silica nanoparticles increased hydrophilicity of the hybrids. Biocompatibility by using human lung epithelial cell line (MRC-5) demonstrated that the hybrids were significantly less cytotoxic compared to pristine polymer as tested by MTT and LDH assays. TUNEL assay revealed no signs of apoptosis in all tested samples. The results of this study demonstrated that incorporation of silica nanoparticles into polyurethane lead to the enhancement of biocompatibility, indicating that these hybrids could potentially be used in biomedical field in particular as a new coating for medical implants.

Vapor-based coatings for antibacterial and osteogenic functionalization and the immunological compatibility

The immobilization of biofunctional molecules to biomaterial surfaces has enabled and expanded the versatility of currently available biomaterials to a wider range of applications. In addition, immobilized biomolecules offer modified surfaces that allow the use of smaller amounts of potentially harmful substances or prevent overdose, while the exhibited biological functions remain persistently effective. Surface concentrations of chlorhexidine (CHX) (1.40±0.08×10(-9)mol·cm(-2)) and bone morphogenetic protein 2 (BMP-2) (1.51±0.08×10(-11)mol·cm(-2)) immobilized molecules were determined in this study, and their specific biological functions in terms of antibacterial activity and osteogenesis potency, respectively, were demonstrated to be unambiguously effective. Immobilization exploits the use of vapor-based poly-p-xylylenes, which exhibit excellent biocompatibility and wide applicability for various substrate materials. This technique represents a practical and economical approach for the manufacture of certain industrial products. Furthermore, a minimal degree of macrophage activation was indicated on the modified surfaces via insignificant morphological changes and low levels of adverse inflammatory signals, including suppressed production of the pro-inflammatory cytokines IL-1β and TNF-α as well as nitric oxide (NO). The results and the modification strategy illustrate a concept for designing prospective biomaterial surfaces such that the manipulation employed to elicit targeted biological responses does not compromise immunological compatibility.

Modification of a commercial thromboelastography instrument to measure coagulation dynamics with three-dimensional biomaterials

Three-dimensional synthetic constructs with complex geometries have immense potential for use in a multitude of blood-contacting applications. Understanding coagulation phenomena is arguably the most critical aspect for applications involving synthetic biomaterials; however, real-time evaluation of the clot formation while interfacing with these materials is difficult to achieve in a reproducible and robust manner. Here, work representing first steps toward addressing this deficit is presented, wherein modified consumables for a clinical instrument (a Thromboelastograph(®)) have been fabricated. Thromboelastography (TEG) measures viscoelastic properties throughout clot formation and therefore provides clinically relevant coagulation measurements in real time (i.e., kinetics and strength of clot formation). Through our modification, TEG consumables can readily accommodate three-dimensional materials (e.g., those for regenerative tissue applications). The authors performed proof-of-concept experiments using polymer scaffolds with a range of surface properties and demonstrated that variations in surface properties resulted in differences in blood plasma coagulation dynamics. For example, the maximum rate of thrombus generation ranged from 22.2 ± 2.2 (dyn/cm(2))/s for fluorocarbon coated scaffolds to 8.7 ± 1.0 (dyn/cm(2))/s for nitrogen-containing scaffolds. Through this work, the ability to make real-time coagulation activity measurements during constant coagulation factor interface with biomedically relevant materials is demonstrated.

Fabrication and characterization of Mg-doped chitosan-gelatin nanocompound coatings for titanium surface functionalization

Titanium and its alloys have been widely used in clinic and achieved great success. Due to the bio-inertness of titanium surface, challenges still exit in some compromised conditions. The present study aimed to functionalize titanium surface with magnesium (Mg)-doped chitosan/gelatin (CS/G) nanocompound coatings via electrophoretic deposition (EPD). CS/G coatings loaded with different amount of magnesium were successfully prepared on titanium substrate via EPD. Physicochemical characterization of the coatings confirmed that magnesium ions were loaded into the coatings in a dose-dependent manner. XRD results demonstrated that co-deposition of magnesium influenced the crystallinity of the coatings, and a new crystalline substance presented, namely hydrated basic magnesium carbonate. Mechanical tests showed improved tensile and shear bond strength of the magnesium-doped coatings, while the excessively high magnesium concentration could eventually decrease the bonding strength. Sustained release of magnesium ion was detected by ICP-OES within 28 days. TEM images also displayed that nanoparticles could be released from the coatings. In vitro cellular response assays demonstrated that the Mg-doped nanocompound coatings could enhance the proliferation and osteogenic differentiation of MC3T3-E1 cells compared to CS/G coatings. Therefore, it could be concluded that Mg-doped CS/G nanocompound coatings were successfully fabricated on titanium substrates via EPD. It would be a promising candidate to functionalize titanium surface with such organic-inorganic nanocompound coatings.

Unravelling the potential of nitric acid as a surface modifier for improving the hemocompatibility of metallocene polyethylene for blood contacting devices

Design of blood compatible surfaces is obligatory to minimize platelet surface interactions and improve the thromboresistance of foreign surfaces when they are utilized as biomaterials particularly for blood contacting devices. Pure metallocene polyethylene (mPE) and nitric acid (HNO3) treated mPE antithrombogenicity and hydrophilicity were investigated. The contact angle of the mPE treated with HNO3 decreased. Surface of mPE and HNO3 treated mPE investigated with FTIR revealed no major changes in its functional groups. 3D Hirox digital microscopy, SEM and AFM images show increased porosity and surface roughness. Blood coagulation assays prothrombin time (PT) and activated partial thromboplastin time (APTT) were delayed significantly (P < 0.05) for HNO3 treated mPE. Hemolysis assay and platelet adhesion of the treated surface resulted in the lysis of red blood cells and platelet adherence, respectively indicating improved hemocompatibility of HNO3 treated mPE. To determine that HNO3 does not deteriorate elastic modulus of mPE, the elastic modulus of mPE and HNO3 treated mPE was compared and the result shows no significant difference. Hence, the overall observation suggests that the novel HNO3 treated mPE may hold great promises to be exploited for blood contacting devices like grafts, catheters, and etc.

Dual-functional anticoagulant and antibacterial blend coatings based on gemini quaternary ammonium salt waterborne polyurethane and heparin

A simple design of the dual-functional anticoagulant and antibacterial blend coatings with controlled release of heparin.

Haemostatic Response of Polyethylene Terephthalate Treated by Oxygen and Nitrogen Plasma Afterglows

Samples of polymer polyethylene terephthalate were coated with heparin and the haemostatic response has been determined by optical imaging of samples after incubation with fresh blood from a healthy donor. Prior to coating the samples were treated by neutral reactive particles of the oxygen or nitrogen plasma flowing afterglow. X-ray photoelectron spectroscopy analysis showed intensive functionalization of the polymer foils upon treatment with afterglows; however, the concentration of sulphur from heparin remained below the detection limit. The optical imaging showed densely distributed blood platelets in highly activated forms on untreated samples, whereas treatment with both afterglows revealed improved hemocompatibility. Best results were obtained for oxygen-functionalized polymer, whereas additional coating with heparin caused moderate loss of hemocompatibility, that was explained by deactivation of surface functional groups upon incubation with heparin.

Preparation of polyetheretherketone composites with nanohydroxyapatite rods and carbon nanofibers having high strength, good biocompatibility and excellent thermal stability

The WST-1 assay shows that the PEEK/15 vol% nHA–1.9 vol% CNF hybrid composite has excellent biocompatibility.