Surface modification of biomaterials and biomedical devices using additive manufacturing

Multifunctional scaffolds for bone repair following age-related biological decline: Promising prospects for smart biomaterial-driven technologies

The repair of large bone defects due to trauma, disease, and infection can be exceptionally challenging in the elderly. Despite best clinical practice, bone regeneration within contemporary, surgically implanted synthetic scaffolds is often problematic, inconsistent, and insufficient where additional osteobiological support is required to restore bone. Emergent smart multifunctional biomaterials may drive important and dynamic cellular crosstalk that directly targets, signals, stimulates, and promotes an innate bone repair response following age-related biological decline and when in the presence of disease or infection. However, their role remains largely undetermined. By highlighting their mechanism/s and mode/s of action, this review spotlights smart technologies that favorably align in their conceivable ability to directly target and enhance bone repair and thus are highly promising for future discovery for use in the elderly. The four degrees of interactive scaffold smartness are presented, with a focus on bioactive, bioresponsive, and the yet-to-be-developed autonomous scaffold activity. Further, cell- and biomolecular-assisted approaches were excluded, allowing for contemporary examination of the capabilities, demands, vision, and future requisites of next-generation biomaterial-induced technologies only. Data strongly supports that smart scaffolds hold significant promise in the promotion of bone repair in patients with a reduced osteobiological response. Importantly, many techniques have yet to be tested in preclinical models of aging. Thus, greater clarity on their proficiency to counteract the many unresolved challenges within the scope of aging bone is highly warranted and is arguably the next frontier in the field. This review demonstrates that the use of multifunctional smart synthetic scaffolds with an engineered strategy to circumvent the biological insufficiencies associated with aging bone is a viable route for achieving next-generation therapeutic success in the elderly population.

Decellularized extracellular matrix coupled with polycaprolactone/laponite to construct a biomimetic barrier membrane for bone defect repair

Barrier membranes play a prominent role in guided bone regeneration (GBR), and polycaprolactone (PCL) is an attractive biomaterial for the fabrication of barrier membranes. However, these nanofiber membranes (NFMs) require modification to improve their biological activity. PCL-NFMs incorporating with laponite (LAP) achieve biofunctional modification. Decellularized extracellular matrix (dECM) could modulate cell behaviour. The present study combined dECM with PCL/LAP-NFMs to generate a promising strategy for bone tissue regeneration. Bone marrow mesenchymal stem cells (BMSCs) were cultured on NFMs and deposited with an abundant extracellular matrix (ECM), which was subsequently decellularized to obtain dECM-modified PCL/LAP-NFMs (PCL/LAP-dECM-NFMs). The biological functions of the membranes were evaluated by reseeding MC3T3-E1 cells in vitro and transplanting them into rat calvarial defects in vivo. These results indicate that PCL/LAP-dECM-NFMs were successfully constructed. The presence of dECM slightly improved the mechanical properties of the NFMs, which exhibited a Young's modulus of 0.269 MPa, ultimate tensile strength of 2.04 MPa and elongation at break of 51.62 %. In vitro, the PCL/LAP-dECM-NFMs had favourable cytocompatibility, and the enhanced hydrophilicity was conducive to cell adhesion, proliferation, and osteoblast differentiation. PCL/LAP-dECM-NFMs exhibited an excellent bone repair capacity in vivo. Overall, dECM-modified PCL/LAP-NFMs should be promising biomimetic barrier membranes for GBR.

Recent Advances in the Modification and Improvement of Bioprosthetic Heart Valves

Valvular heart disease (VHD) has become a burden and a growing public health problem in humans, causing significant morbidity and mortality worldwide. An increasing number of patients with severe VHD need to undergo heart valve replacement surgery, and artificial heart valves are in high demand. However, allogeneic valves from donors are lacking and cannot meet clinical practice needs. A mechanical heart valve can activate the coagulation pathway after contact with blood after implantation in the cardiovascular system, leading to thrombosis. Therefore, bioprosthetic heart valves (BHVs) are still a promising way to solve this problem. However, there are still challenges in the use of BHVs. For example, their longevity is still unsatisfactory due to the defects, such as thrombosis, structural valve degeneration, calcification, insufficient re-endothelialization, and the inflammatory response. Therefore, strategies and methods are needed to effectively improve the biocompatibility and longevity of BHVs. This review describes the recent research advances in BHVs and strategies to improve their biocompatibility and longevity.

Fast and Stable Antibacterial Coating of Photosensitive Aggregation-Induced Emission Luminogens for Disinfection on Medical Devices

Aggregation-induced emission luminogens (AIEgens) are promising photosensitizers that have exhibited excellent antibacterial ability with abundant reactive oxygen species (ROS) generation. TTCPy-PF6 and TTCPy-Br are deposited on the surface of diverse solid substrates through plasma-assistant electrostatic self-assembly. The AIEgens-covered coating can effectively eliminate different pathogenic Gram-positive (G+) bacteria and even their multidrug-resistant (MDR) mutants with negligible side effects such as cytotoxicity, hemolysis, and inflammation. Moreover, the AIEgen-coated surface can maintain high stability for long-time antibacterial usage, which is dependent on the ROS-mediated disruption of the attached bacteria. The AIEgen-based coatings with broad surface applicability have many advantages in high antibacterial ability, great biocompatibility, and low possibility of antibiotic pollution. The robust antibacterial ability and excellent biological safety of the AIEgen-based coatings would be helpful for the disinfection of medical devices.

Recent Advances in Two-Dimensional Nanomaterials for Healthcare Monitoring

The development of advanced technologies for the fabrication of functional nanomaterials, nanostructures, and devices has facilitated the development of biosensors for analyses. Two-dimensional (2D) nanomaterials, with unique hierarchical structures, a high surface area, and the ability to be functionalized for target detection at the surface, exhibit high potential for biosensing applications. The electronic properties, mechanical flexibility, and optical, electrochemical, and physical properties of 2D nanomaterials can be easily modulated, enabling the construction of biosensing platforms for the detection of various analytes with targeted recognition, sensitivity, and selectivity. This review provides an overview of the recent advances in 2D nanomaterials and nanostructures used for biosensor and wearable-sensor development for healthcare and health-monitoring applications. Finally, the advantages of 2D-nanomaterial-based devices and several challenges in their optimal operation have been discussed to facilitate the development of smart high-performance biosensors in the future.

In Vitro Characterization of Hydroxyapatite-Based Coatings Doped with Mg or Zn Electrochemically Deposited on Nanostructured Titanium

Biomaterials are an important and integrated part of modern medicine, and their development and improvement are essential. The fundamental requirement of a biomaterial is found to be in its interaction with the surrounding environment, with which it must coexist. The aim of this study was to assess the biological characteristics of hydroxyapatite (HAp)-based coatings doped with Mg and Zn ions obtained by the pulsed galvanostatic electrochemical method on the surface of pure titanium (cp-Ti) functionalized with titanium dioxide nanotubes (NTs TiO2) obtained by anodic oxidation. The obtained results highlighted that the addition of Zn or Mg into the HAp structure enhances the in vitro response of the cp-Ti surface functionalized with NT TiO2. The contact angle and surface free energy showed that all the developed surfaces have a hydrophilic character in comparison with the cp-Ti surface. The HAp-based coatings doped with Zn registered superior values than the ones with Mg, in terms of biomineralization, electrochemical behavior, and cell interaction. Overall, it can be said that the addition of Mg or Zn can enhance the in vitro behavior of the HAp-based coatings in accordance with clinical requirements. Antibacterial tests showed that the proposed HAp-Mg coatings had no efficiency against Escherichia coli, while the HAp-Zn coatings registered the highest antibacterial efficiency.

Layer-by-layer assembly of nanotheranostic particles for simultaneous delivery of docetaxel and doxorubicin to target osteosarcoma

Osteosarcoma (OS) is a rare form of primary bone cancer, impacting approximately 3.4 × 106 individuals worldwide each year, primarily afflicting children. Given the limitations of existing cancer therapies, the emergence of nanotheranostic platforms has generated considerable research interest in recent decades. These platforms seamlessly integrate therapeutic potential of drug compounds with the diagnostic capabilities of imaging probes within a single construct. This innovation has opened avenues for enhanced drug delivery to targeted sites while concurrently enabling real-time monitoring of the vehicle's trajectory. In this study, we developed a nanotheranostic system employing the layer-by-layer (LbL) technique on a core containing doxorubicin (DOXO) and in-house synthesized carbon quantum dots. By utilizing chitosan and chondroitin sulfate as polyelectrolytes, we constructed a multilayered coating to encapsulate DOXO and docetaxel, achieving a coordinated co-delivery of both drugs. The LbL-functionalized nanoparticles exhibited an approximate size of 150 nm, manifesting a predominantly uniform and spherical morphology, with an encapsulation efficiency of 48% for both drugs. The presence of seven layers in these systems facilitated controlled drug release over time, as evidenced by in vitro release tests. Finally, the impact of the LbL-functionalized nanoparticles was evaluated on U2OS and Saos-2 osteosarcoma cells. The synergistic effect of the two drugs was found to be crucial in inducing cell death, particularly in Saos-2 cells treated with nanoparticles at concentrations higher than 10 μg/ml. Transmission electron microscopy analysis confirmed the internalization of the nanoparticles into both cell types through endocytic mechanisms, revealing an underlying mechanism of necrosis-induced cell death.

Stimuli-responsive Biomaterials for Tissue Engineering Applications

The use of ''smart materials,'' or ''stimulus responsive'' materials, has proven useful in a variety of fields, including tissue engineering and medication delivery. Many factors, including temperature, pH, redox state, light, and magnetic fields, are being studied for their potential to affect a material's properties, interactions, structure, and/or dimensions. New tissue engineering and drug delivery methods are made possible by the ability of living systems to respond to both external stimuli and their own internal signals) for example, materials composed of stimuliresponsive polymers that self assemble or undergo phase transitions or morphology transformation. The researcher examines the potential of smart materials as controlled drug release vehicles in tissue engineering, aiming to enable the localized regeneration of injured tissue by delivering precisely dosed drugs at precisely timed intervals.

ε-Poly-l-lysine-hydroxyphenyl propionic acid/IL-4 composite hydrogels with inflammation regulation and antibacterial activity for improving integration stability of soft tissues and orthopedic implants

The failure of orthopedic implants is usually caused by inflammation, poor tissue integration, and infection, which can lead to pain, limited mobility, dysfunction of patients. This may require additional surgical interventions, such as removal, replacement, or repair of implants, as well as related treatment measures such as antibiotic therapy, physical therapy. Here, an injectable hydrogel carrier was developed for the steady release of inflammatory regulators to reduce the surface tissue inflammatory response of orthopedic implants and induce soft tissue regeneration, ultimately achieving the promotion of implants stability. The hydrogels carrier was prepared by hydroxyphenyl propionic acid-modified ε-Poly-l-lysine (EPA), hydrogen peroxide and horseradish peroxidase, which showed antibacterial bioactive and stable factor release ability. Due to the introduction of IL-4, EPA@IL-4 hydrogels showed good inflammatory regulation. EPA@IL-4 hydrogels regulated the differentiation of macrophages into M2 in inflammatory environment in vitro, and promoted endothelial cells to show a more obvious trend of tube formation. The composite hydrogels reduced the inflammation on the surface of the implants in vivo, induced local endothelial cell angiogenesis, and had more collagen deposition and new granulation tissue. Therefore, EPA hydrogels based on IL-4 release are promising candidates for promoting of implants surface anti-inflammatory, soft tissue regeneration, and anti-infection.

Natural medicine delivery from 3D printed bone substitutes

Unmet medical needs in treating critical-size bone defects have led to the development of numerous innovative bone tissue engineering implants. Although additive manufacturing allows flexible patient-specific treatments by modifying topological properties with various materials, the development of ideal bone implants that aid new tissue regeneration and reduce post-implantation bone disorders has been limited. Natural biomolecules are gaining the attention of the health industry due to their excellent safety profiles, providing equivalent or superior performances when compared to more expensive growth factors and synthetic drugs. Supplementing additive manufacturing with natural biomolecules enables the design of novel multifunctional bone implants that provide controlled biochemical delivery for bone tissue engineering applications. Controlled release of naturally derived biomolecules from a three-dimensional (3D) printed implant may improve implant-host tissue integration, new bone formation, bone healing, and blood vessel growth. The present review introduces us to the current progress and limitations of 3D printed bone implants with drug delivery capabilities, followed by an in-depth discussion on cutting-edge technologies for incorporating natural medicinal compounds embedded within the 3D printed scaffolds or on implant surfaces, highlighting their applications in several pre- and post-implantation bone-related disorders.

Effect of Atmospheric Pressure Plasma Jet Treatments on Magnesium Phosphate Cements: Performance, Characterization, and Applications

Atmospheric pressure plasma treatments are nowadays gaining importance to improve the performance of biomaterials in the orthopedic field. Among those, magnesium phosphate-based cements (MPCs) have recently shown attractive features as bone repair materials. The effect of plasma treatments on such cements, which has not been investigated so far, could represent an innovative strategy to modify MPCs' physicochemical properties and to tune their interaction with cells. MPCs were prepared and treated for 5, 7.5, and 10 min with a cold atmospheric pressure plasma jet. The reactive nitrogen and oxygen species formed during the treatment were characterized. The surfaces of MPCs were studied in terms of the phase composition, morphology, and topography. After a preliminary test in simulated body fluid, the proliferation, adhesion, and osteogenic differentiation of human mesenchymal cells on MPCs were assessed. Plasma treatments induce modifications in the relative amounts of struvite, newberyite, and farringtonite on the surfaces on MPCs in a time-dependent fashion. Nonetheless, all investigated scaffolds show a good biocompatibility and cell adhesion, also supporting osteogenic differentiation of mesenchymal cells.

Shaping the Future of Antimicrobial Therapy: Harnessing the Power of Antimicrobial Peptides in Biomedical Applications

Antimicrobial peptides (AMPs) have emerged as a promising class of bioactive molecules with the potential to combat infections associated with medical implants and biomaterials. This review article aims to provide a comprehensive analysis of the role of antimicrobial peptides in medical implants and biomaterials, along with their diverse clinical applications. The incorporation of AMPs into various medical implants and biomaterials has shown immense potential in mitigating biofilm formation and preventing implant-related infections. We review the latest advancements in biomedical sciences and discuss the AMPs that were immobilized successfully to enhance their efficacy and stability within the implant environment. We also highlight successful examples of AMP coatings for the treatment of surgical site infections (SSIs), contact lenses, dental applications, AMP-incorporated bone grafts, urinary tract infections (UTIs), medical implants, etc. Additionally, we discuss the potential challenges and prospects of AMPs in medical implants, such as effectiveness, instability and implant-related complications. We also discuss strategies that can be employed to overcome the limitations of AMP-coated biomaterials for prolonged longevity in clinical settings.

Aminosilane Functionalized Aligned Fiber PCL Scaffolds for Peripheral Nerve Repair

Silane modification is a simple and cost-effective tool to modify existing biomaterials for tissue engineering applications. Aminosilane layer deposition has previously been shown to control NG108-15 neuronal cell and primary Schwann cell adhesion and differentiation by controlling deposition of ─NH2 groups at the submicron scale across the entirety of a surface by varying silane chain length. This is the first study toreport depositing 11-aminoundecyltriethoxysilane (CL11) onto aligned Polycaprolactone (PCL) scaffolds for peripheral nerve regeneration. Fibers are manufactured via electrospinning and characterized using water contact angle measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Confirmed modified fibers are investigated using in vitro cell culture of NG108-15 neuronal cells and primary Schwann cells to determine cell viability, cell differentiation, and phenotype. CL11-modified fibers significantly support NG108-15 neuronal cell and Schwann cell viability. NG108-15 neuronal cell differentiation maintains Schwann cell phenotype compared to unmodified PCL fiber scaffolds. 3D ex vivo culture of Dorsal root ganglion explants (DRGs) confirms further Schwann cell migration and longer neurite outgrowth from DRG explants cultured on CL11 fiber scaffolds compared to unmodified scaffolds. Thus, a reproducible and cost-effective tool is reported to modify biomaterials with functional amine groups that can significantly improve nerve guidance devices and enhance nerve regeneration.

Exosome-bearing hydrogels and cardiac tissue regeneration

BACKGROUND

In recent years, cardiovascular disease in particular myocardial infarction (MI) has become the predominant cause of human disability and mortality in the clinical setting. The restricted capacity of adult cardiomyocytes to proliferate and restore the function of infarcted sites is a challenging issue after the occurrence of MI. The application of stem cells and byproducts such as exosomes (Exos) has paved the way for the alleviation of cardiac tissue injury along with conventional medications in clinics. However, the short lifespan and activation of alloreactive immune cells in response to Exos and stem cells are the main issues in patients with MI. Therefore, there is an urgent demand to develop therapeutic approaches with minimum invasion for the restoration of cardiac function.

MAIN BODY

Here, we focused on recent data associated with the application of Exo-loaded hydrogels in ischemic cardiac tissue. Whether and how the advances in tissue engineering modalities have increased the efficiency of whole-based and byproducts (Exos) therapies under ischemic conditions. The integration of nanotechnology and nanobiology for designing novel smart biomaterials with therapeutic outcomes was highlighted.

CONCLUSION

Hydrogels can provide suitable platforms for the transfer of Exos, small molecules, drugs, and other bioactive factors for direct injection into the damaged myocardium. Future studies should focus on the improvement of physicochemical properties of Exo-bearing hydrogel to translate for the standard treatment options.

Phytoremediative adsorption methodologies to decontaminate water from dyes and organic pollutants

Persistent organic pollutants and dyes cause major problems during ecofriendly wastewater treatment. To overcome this huge problem, several techniques have been considered and in practice for the safe disposal of organic pollutants in recent years; some of them are discussed and compared herein. This review focuses on new trends for wastewater treatment and compares them with certain other techniques alongside their pros and cons; adsorption is considered the safest among them. Adsorbents derived from agri-wastes have good capacity for the removal of these contaminants owing to their great sorption capacity, high reusability, easy operation, etc. Sometimes they need some modifications for the removal of dyes, which are also discussed in this review. This capacity of adsorbents to chelate dye molecules can be affected by factors, such as pH, the concentration of dyes and adsorbents, and temperature of the system. pH has direct influence on the ionization potential and charge on the outer surface of adsorbents. The findings on isotherms, kinetics, and desorption of plant waste-based biomaterials that are safe for the ecosystem and user friendly and are used for hazardous contaminant removal from water are summarized in this review. Finally, conclusions and future perspectives are presented, and some other materials, such as CNTs and MOFs, are also discussed as efficient adsorbents for eliminating dyes from wastewater. Finally, it is predicted that the adsorption of dyes is a more feasible solution for this dye pollution problem.

Porous metal implants: processing, properties, and challenges

Porous and functionally graded materials have seen extensive applications in modern biomedical devices-allowing for improved site-specific performance; their appreciable mechanical, corrosive, and biocompatible properties are highly sought after for lightweight and high-strength load-bearing orthopedic and dental implants. Examples of such porous materials are metals, ceramics, and polymers. Although, easy to manufacture and lightweight, porous polymers do not inherently exhibit the required mechanical strength for hard tissue repair or replacement. Alternatively, porous ceramics are brittle and do not possess the required fatigue resistance. On the other hand, porous biocompatible metals have shown tailorable strength, fatigue resistance, and toughness. Thereby, a significant interest in investigating the manufacturing challenges of porous metals has taken place in recent years. Past research has shown that once the advantages of porous metallic structures in the orthopedic implant industry have been realized, their biological and biomechanical compatibility-with the host bone-has been followed up with extensive methodical research. Various manufacturing methods for porous or functionally graded metals are discussed and compared in this review, specifically, how the manufacturing process influences microstructure, graded composition, porosity, biocompatibility, and mechanical properties. Most of the studies discussed in this review are related to porous structures for bone implant applications; however, the understanding of these investigations may also be extended to other devices beyond the biomedical field.

3D printing metal implants in orthopedic surgery: Methods, applications and future prospects

Background

Currently, metal implants are widely used in orthopedic surgeries, including fracture fixation, spinal fusion, joint replacement, and bone tumor defect repair. However, conventional implants are difficult to be customized according to the recipient's skeletal anatomy and defect characteristics, leading to difficulties in meeting the individual needs of patients. Additive manufacturing (AM) or three-dimensional (3D) printing technology, an advanced digital fabrication technique capable of producing components with complex and precise structures, offers opportunities for personalization.

Methods

We systematically reviewed the literature on 3D printing orthopedic metal implants over the past 10 years. Relevant animal, cellular, and clinical studies were searched in PubMed and Web of Science. In this paper, we introduce the 3D printing method and the characteristics of biometals and summarize the properties of 3D printing metal implants and their clinical applications in orthopedic surgery. On this basis, we discuss potential possibilities for further generalization and improvement.

Results

3D printing technology has facilitated the use of metal implants in different orthopedic procedures. By combining medical images from techniques such as CT and MRI, 3D printing technology allows the precise fabrication of complex metal implants based on the anatomy of the injured tissue. Such patient-specific implants not only reduce excessive mechanical strength and eliminate stress-shielding effects, but also improve biocompatibility and functionality, increase cell and nutrient permeability, and promote angiogenesis and bone growth. In addition, 3D printing technology has the advantages of low cost, fast manufacturing cycles, and high reproducibility, which can shorten patients' surgery and hospitalization time. Many clinical trials have been conducted using customized implants. However, the use of modeling software, the operation of printing equipment, the high demand for metal implant materials, and the lack of guidance from relevant laws and regulations have limited its further application.

Conclusions

There are advantages of 3D printing metal implants in orthopedic applications such as personalization, promotion of osseointegration, short production cycle, and high material utilization. With the continuous learning of modeling software by surgeons, the improvement of 3D printing technology, the development of metal materials that better meet clinical needs, and the improvement of laws and regulations, 3D printing metal implants can be applied to more orthopedic surgeries.

The translational potential of this paper

Precision, intelligence, and personalization are the future direction of orthopedics. It is reasonable to believe that 3D printing technology will be more deeply integrated with artificial intelligence, 4D printing, and big data to play a greater role in orthopedic metal implants and eventually become an important part of the digital economy. We aim to summarize the latest developments in 3D printing metal implants for engineers and surgeons to design implants that more closely mimic the morphology and function of native bone.

Engineered and Durable Antimicrobial Polymer via Controllable Immobilization of Ionic Liquids onto the Poly(lactic acid) Chains

Nowadays, the development of effective modification methods for PLA has gained significant interest because of the wide application of antimicrobial PLA materials in the medical progress. Herein, the ionic liquid (IL) 1-vinyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide, has been grafted onto the PLA chains successfully in the PLA/IL blending films via electron beam (EB) radiation for the miscibility between PLA and IL. It was found that the existence of IL in the PLA matrix can significantly improve the chemical stability under EB radiation. The Mn of PLA-g-IL copolymer did not change obviously but was just decreased from 6.80 × 104 g/mol to 5.20 × 104 g/mol after radiation with 10 kGy. The obtained PLA-g-IL copolymers showed excellent filament forming property during electrospinning process. The spindle structure on the nanofibers can be completely eliminated after feeding only 0.5 wt % ILs for the improvement of ionic conductivity. Specially, the prepared PLA-g-IL nonwovens exhibited outstanding and durable antimicrobial activity for the enrichment of immobilized ILs on the nanofiber surface. This work provides a feasible strategy to realize the modification of functional ILs onto PLA chains with low EB radiation doses, which may have huge potential application in the medical and packaging industry.

An overview of 3D printed metal implants in orthopedic applications: Present and future perspectives

With the ability to produce components with complex and precise structures, additive manufacturing or 3D printing techniques are now widely applied in both industry and consumer markets. The emergence of tissue engineering has facilitated the application of 3D printing in the field of biomedical implants. 3D printed implants with proper structural design can not only eliminate the stress shielding effect but also improve in vivo biocompatibility and functionality. By combining medical images derived from technologies such as X-ray scanning, CT, MRI, or ultrasonic scanning, 3D printing can be used to create patient-specific implants with almost the same anatomical structures as the injured tissues. Numerous clinical trials have already been conducted with customized implants. However, the limited availability of raw materials for printing and a lack of guidance from related regulations or laws may impede the development of 3D printing in medical implants. This review provides information on the current state of 3D printing techniques in orthopedic implant applications. The current challenges and future perspectives are also included.

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

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

Bone marrow stromal cells are sensitive to discrete surface alterations in build and post-build modifications of bioinspired Ti6Al4V 3D-printed in vitro testing constructs

Current standards in bone-facing implant fabrication by metal 3D (M3D) printing require post-manufacturing modifications to create distinct surface properties and create implant microenvironments that promote osseointegration. However, the biological consequences of build parameters and surface modifications are not well understood. This study evaluated the relative contributions of build parameters and post-manufacturing modification techniques to cell responses that impact osseointegration in vivo. Biomimetic testing constructs were created by using a M3D printer with standard titanium-aluminum-vanadium (Ti6Al4V) print parameters. These constructs were treated by either grit-blasting and acid-etching (GB + AE) or GB + AE followed by hot isostatic pressure (HIP) (GB + AE, HIP). Next, nine constructs were created by using a M3D printer with three build parameters: (1) standard, (2) increased hatch spacing, and (3) no infill, and additional contour trace. Each build type was further processed by either GB + AE, or HIP, or a combination of HIP treatment followed by GB + AE (GB + AE, HIP). Resulting constructs were assessed by SEM, micro-CT, optical profilometry, XPS, and mechanical compression. Cellular response was determined by culturing human bone marrow stromal cells (MSCs) for 7 days. Surface topography differed depending on processing method; HIP created micro-/nano-ridge like structures and GB + AE created micro-pits and nano-scale texture. Micro-CT showed decreases in closed pore number and closed porosity after HIP treatment in the third build parameter constructs. Compressive moduli were similar for all constructs. All constructs exhibited ability to differentiate MSCs into osteoblasts. MSCs responded best to micro-/nano-structures created by final post-processing by GB + AE, increasing OCN, OPG, VEGFA, latent TGFβ1, IL4, and IL10. Collectively these data demonstrate that M3D-printed constructs can be readily manufactured with distinct architectures based on the print parameters and post-build modifications. MSCs are sensitive to discrete surface topographical differences that may not show up in qualitative assessments of surface properties and respond by altering local factor production. These factors are vital for osseointegration after implant insertion, especially in patients with compromised bone qualities.

Biofilm inspired fabrication of functional bacterial cellulose through ex-situ and in-situ approaches

Bacterial cellulose (BC) has been explored for use in a range of applications including tissue engineering and textiles. BC can be produced from waste streams, but sustainable approaches are needed for functionalisation. To this end, BslA, a B. subtilis biofilm protein was produced recombinantly with and without a cellulose binding module (CBM) and the cell free extract was used to treat BC either ex-situ, through drip coating or in-situ, by incorporating during fermentation. The results showed that ex-situ modified BC increased the hydrophobicity and water contact angle reached 120°. In-situ experiments led to a BC film morphological change and mechanical testing demonstrated that addition of BslA with CBM resulted in a stronger, more elastic material. This study presents a nature inspired approach to functionalise BC using a biofilm hydrophobin, and we demonstrate that recombinant proteins could be effective and sustainable molecules for functionalisation of BC materials.

Improving Biocompatibility for Next Generation of Metallic Implants

The increasing need for joint replacement surgeries, musculoskeletal repairs, and orthodontics worldwide prompts emerging technologies to evolve with healthcare's changing landscape. Metallic orthopaedic materials have a shared application history with the aerospace industry, making them only partly efficient in the biomedical domain. However, suitability of metallic materials in bone tissue replacements and regenerative therapies remains unchallenged due to their superior mechanical properties, eventhough they are not perfectly biocompatible. Therefore, exploring ways to improve biocompatibility is the most critical step toward designing the next generation of metallic biomaterials. This review discusses methods of improving biocompatibility of metals used in biomedical devices using surface modification, bulk modification, and incorporation of biologics. Our investigation spans multiple length scales, from bulk metals to the effect of microporosities, surface nanoarchitecture, and biomolecules such as DNA incorporation for enhanced biological response in metallic materials. We examine recent technologies such as 3D printing in alloy design and storing surface charge on nanoarchitecture surfaces, metal-on-metal, and ceramic-on-metal coatings to present a coherent and comprehensive understanding of the subject. Finally, we consider the advantages and challenges of metallic biomaterials and identify future directions.

Two dimensional (2D) materials and biomaterials for water desalination; structure, properties, and recent advances

BACKGROUND

An efficient solution to the global freshwater dilemma is desalination. MXene, Molybdenum Disulfide (MoS₂), Graphene Oxide, Hexagonal Boron Nitride, and Phosphorene are just a few examples of two-dimensional (2D) materials that have shown considerable promise in the development of 2D materials for water desalination. However, other promising materials for desalinating water are biomaterials. The benefits of bio-materials are their wide distribution, lack of toxicity, and superior capacity for water desalination.

METHODS

For the rational use of water and the advancement of sustainable development, it is of the utmost importance to research 2D-dimensional materials and biomaterials that are effective for water desalination. The scientific community has concentrated on wastewater remediation using bio-derived materials, such as nanocellulose, chitosan, bio-char, bark, and activated charcoal generated from plant sources, among the various endeavors to enhance access to clean water. Moreover, the 2D-materials and biomaterials may have ushered in a new age in the production of desalination materials and created a promising future.

RESULTS

The present review article focuses on and reviews the progress of 2D materials and biomaterials for water desalination. Their properties, surface, and structure, combined with water desalination applications, are highlighted. Further, the practicability and potential future directions of 2D materials and biomaterials are proposed. Thus, the current work provides information and discernments for developing novel 2D materials and biomaterials for wastewater desalination. Moreover, it aims to promote the contribution and advancement of materials for water desalination, fabrication, and industrial production.

Use of Piranha Solution as An Alternative Route to Promote Bioactivation of PEEK Surface with Low Functionalization Times

This study aimed to achieve bioactivity on the PEEK surface using piranha solution through a lower functionalization time. For this purpose, the functionalization occurred with piranha solution and 98% sulfuric acid in the proportions of 1:2, 1:1, and 2:1 at periods of 30, 60, and 90 s. The samples treated for longer times at higher concentrations registered the characteristic spectroscopy band associated with sulfonation. Additionally, both chemical treatments allowed the opening of the aromatic ring, increasing the number of functional groups available and making the surface more hydrophilic. The piranha solution treatments with higher concentrations and longer times promoted greater heterogeneity in the surface pores, which affected the roughness of untreated PEEK. Furthermore, the treatments induced calcium deposition on the surface during immersion in SBF fluid. In conclusion, the proposed chemical modifications using sulfuric acid SPEEK 90 and, especially, the piranha solution PEEK-PS 2:1-90, were demonstrated to be promising in promoting the rapid bioactivation of PEEK-based implants.

Surface Texturing and Combinatorial Approaches to Improve Biocompatibility of Implanted Biomaterials

Biomaterial associated microbial infection and blood thrombosis are two of the barriers that inhibit the successful use of implantable medical devices in modern healthcare. Modification of surface topography is a promising approach to combat microbial infection and thrombosis without altering bulk material properties necessary for device function and without contributing to bacterial antibiotic resistance. Similarly, the use of other antimicrobial techniques such as grafting poly(ethylene glycol) (PEG) and nitric oxide (NO) release also improve the biocompatibility of biomaterials. In this review, we discuss the development of surface texturing techniques utilizing ordered submicron-size pillars for controlling bacterial adhesion and biofilm formation, and we present combinatorial approaches utilizing surface texturing in combination with poly(ethylene glycol) (PEG) grafting and NO release to improve the biocompatibility of biomaterials. The manuscript also discusses efforts towards understanding the molecular mechanisms of bacterial adhesion responses to the surface texturing and NO releasing biomaterials, focusing on experimental aspects of the approach.

Tailoring bioinks of extrusion-based bioprinting for cutaneous wound healing

Extrusion-based bioprinting (EBB) holds potential for regenerative medicine. However, the widely-used bioinks of EBB exhibit some limitations for skin regeneration, such as unsatisfactory bio-physical (i.e., mechanical, structural, biodegradable) properties and compromised cellular compatibilities, and the EBB-based bioinks with therapeutic effects targeting cutaneous wounds still remain largely undiscussed. In this review, the printability considerations for skin bioprinting were discussed. Then, current strategies for improving the physical properties of bioinks and for reinforcing bioinks in EBB approaches were introduced, respectively. Notably, we highlighted the applications and effects of current EBB-based bioinks on wound healing, wound scar formation, vascularization and the regeneration of skin appendages (i.e., sweat glands and hair follicles) and discussed the challenges and future perspectives. This review aims to provide an overall view of the applications, challenges and promising solutions about the EBB-based bioinks for cutaneous wound healing and skin regeneration.

Recent advances in surface modification of micro- and nano-scale biomaterials with biological membranes and biomolecules

Surface modification of biomaterial can improve its biocompatibility and add new biofunctions, such as targeting specific tissues, communication with cells, and modulation of intracellular trafficking. Here, we summarize the use of various natural materials, namely, cell membrane, exosomes, proteins, peptides, lipids, fatty acids, and polysaccharides as coating materials on micron- and nano-sized particles and droplets with the functions imparted by coating with different materials. We discuss the applicability, operational parameters, and limitation of different coating techniques, from the more conventional approaches such as extrusion and sonication to the latest innovation seen on the microfluidics platform. Methods commonly used in the field to examine the coating, including its composition, physical dimension, stability, fluidity, permeability, and biological functions, are reviewed.

Evaluating polymeric biomaterials to improve next generation wound dressing design

Wound healing is a dynamic series of interconnected events with the ultimate goal of promoting neotissue formation and restoration of anatomical function. Yet, the complexity of wound healing can often result in development of complex, chronic wounds, which currently results in a significant strain and burden to our healthcare system. The advancement of new and effective wound care therapies remains a critical issue, with the current therapeutic modalities often remaining inadequate. Notably, the field of tissue engineering has grown significantly in the last several years, in part, due to the diverse properties and applications of polymeric biomaterials. The interdisciplinary cohesion of the chemical, biological, physical, and material sciences is pertinent to advancing our current understanding of biomaterials and generating new wound care modalities. However, there is still room for closing the gap between the clinical and material science realms in order to more effectively develop novel wound care therapies that aid in the treatment of complex wounds. Thus, in this review, we discuss key material science principles in the context of polymeric biomaterials, provide a clinical breadth to discuss how these properties affect wound dressing design, and the role of polymeric biomaterials in the innovation and design of the next generation of wound dressings.

A novel chitosan and polydopamine interlinked bioactive coating for metallic biomaterials

Chitosan coatings have shown good bioactive properties such as antibacterial and antiplatelet properties, especially on blood-contacted biomedical materials. However, as blood-contacted biomedical device, the intravascular metal stent has a burden with adverse effects on the structural integrity, such as mechanical load during implantation and substrate degradation if a biodegradable metal is used as the substrate. It is unquestionably true that the structural integrity of the coated stent is essential. The adhesion strength between the coating and the substrate positively affects it. Silane and polydopamine (PDA) interstitial layers have been investigated to improve the corrosion resistance, biosafety and adhesion strength. This work addressed this challenge by using PDA as an intermediate and glutaraldehyde as a linking agent to establish a strong link between the polymer coating and the intermediate coating. Compared with PDA-only and glutaraldehyde-linked silane layer, the novel coating displayed a notable increase in adhesion. When compared with the bare Ni-free stainless steel, the performance of the novel coating was not significantly different. This novel chitosan film on the glutaraldehyde linked-PDA interface can be applied to various metallic substrates where synergic bioactive and anticorrosive effects of PDA interstitial coating and chitosan are needed. Graphical abstract.

Nitinol: From historical milestones to functional properties and biomedical applications

Isoatomic NiTi alloy (Nitinol) has become an important biomaterial due to its unique characteristics, including shape memory effect, superelasticity, and high damping. Nitinol has been widely used in the biomedical field, including orthopedics, vascular stents, orthodontics, and other medical devices. However, there have been convicting views about the biocompatibility of Nitinol. Some studies have shown that Nitinol has extremely low cytotoxicity, indicating Nitinol has good biocompatibility. However, some studies have shown that the in-vivo corrosion resistance of Nitinol significantly decreases. This comprehensive paper discusses the historical developments of Nitinol, its biomedical applications, and its specific functional property. These render the suitability of Nitinol for such biomedical applications and provide insights into its in vivo and in vitro biocompatibility in the physiological environment and the antimicrobial strategies that can be applied to enhance its biocompatibility. Although 3D metal printing is still immature and Nitinol medical materials are difficult to be processed, Nitinol biomaterials have excellent potential and commercial value for 3D printing. However, there are still significant problems in the processing of Nitinol and improving its biocompatibility. With the deepening of research and continuous progress in surface modification and coating technology, a series of medical devices made from Nitinol are expected to be released soon.

Gas Cluster Ion Beams as a Versatile Soft-Landing Tool for the Controlled Construction of Thin (Bio)Films

Surface biofunctionalization with proteins is the key to many biomedical applications. In this study, a solvent-free method for the controlled construction of protein thin films is reported. Using large argon gas cluster ion beams, proteins are sputtered from a target (a pool of pure proteins), and collected on a chosen substrate, being nearly any solid material. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed the presence of intact protein molecules on the collectors. Furthermore, lowering the energy per atom in the cluster projectiles down to 1 eV/atom allowed more than 60% of bradykinin molecules to be transferred intact. This protein deposition method offers a precise control of the film thickness as the transferred protein quantity is proportional to the argon clusters ion dose reached for the transfer. This major feature enables building protein films from (sub)mono- to multilayers, without upper limitation of the thickness. A procedure was developed to measure the film thickness in situ the ToF-SIMS instrument. The versatility and potential of this soft-landing alternative for further applications is demonstrated on the one hand by building a protein thin film at the surface of paper, a substrate hardly compatible with solution-based adsorption methods. On the other hand, the possibility to achieve alternated multilayer buildup is demonstrated with the construction of a bilayer composed of bradykinin and Irganox, with the two layers well separated. These results lay the first stone toward original and complex multilayers that could previously not be considered with solution-based adsorption methods, and this regardless of the substrate nature.

Towards non-wettable neural electrodes for a minimized foreign body reaction

Functionality of neural implants can be seriously impaired by scarring during the foreign body reaction (FBR). Tailoring of the material-tissue interface is supposed to modulate part of the FBR. Surface structures might physically modulate the foreign body reaction in the acute phase directly after implantation. This work focuses on fabrication and characterization of bioinspired microtextures comprising reentrant cavities with non-wettable surface characteristics. The Selected microstructure patterns were fabricated using direct laser writing and were characterized by means of contact angle measurements and immersion tests. Clinical Relevance-Suggested by the outcome of this study, the proposed surface characteristics in neural interface can impact the wetting properties of the interface, hence, influence the interaction between the body fluid with the surface of the neural implant. Future studies should address the impact of the suggested design criterion and their applicability in improving the long-term stability of neural implants.

Quercetin-Coating Promotes Osteogenic Differentiation, Osseointegration and Anti-Inflammatory Properties of Nano-Topographic Modificated 3D-Printed Ti6Al4V Implant

The capabilities of osseointegration and anti-inflammatory properties are of equal significance to the bio-inert titanium implant surface. Quercetin has proved its capacities of activating anti-inflammation through macrophage modulation and promoting osteogenic differentiation. Herein, we fabricated quercetin-coating on nano-topographic modificated 3D-printed Ti6Al4V implant surface. Subsequently the biological cells responses in vitro, anti-inflammatory and osseointegration performance in vivo were evaluated. In vitro studies indicated that quercetin-coating can enhance the adhesion and osteogenic differentiation of rBMSCs, while modulating the polarization of macrophages from M1 to M2 phase and improving the anti-inflammatory and vascular gene expression. Moreover, quercetin-loaded implants reduced the level of peri-implant inflammation and ameliorated new bone formation and rapid osseoinegration in vivo. Quercetin-coating might provide a feasible and favorable scheme for endowing 3D-printed titanium alloy implant surface with enhanced the rapid osseointegration and anti-inflammatory properties.

Advancements in left ventricular assist devices to prevent pump thrombosis and blood coagulopathy

Mechanical circulatory support (MCS) devices, such as left ventricular assist devices (LVADs) are very useful in improving outcomes in patients with advanced-stage heart failure. Despite recent advances in LVAD development, pump thrombosis is one of the most severe adverse events caused by LVADs. The contact of blood with artificial materials of LVAD pumps and cannulas triggers the coagulation cascade. Heat spots, for example, produced by mechanical bearings are often subjected to thrombus build-up when low-flow situations impair washout and thus the necessary cooling does not happen. The formation of thrombus in an LVAD may compromise its function, causing a drop in flow and pumping power leading to failure of the LVAD, if left unattended. If a clot becomes dislodged and circulates in the bloodstream, it may disturb the flow or occlude the blood vessels in vital organs and cause internal damage that could be fatal, for example, ischemic stroke. That is why patients with LVADs are on anti-coagulant medication. However, the anti-coagulants can cause a set of issues for the patient-an example of gastrointestinal (GI) bleeding is given in illustration. On account of this, these devices are only used as a last resort in clinical practice. It is, therefore, necessary to develop devices with better mechanics of blood flow, performance and hemocompatibility. This paper discusses the development of LVADs through landmark clinical trials in detail and describes the evolution of device design to reduce the risk of pump thrombosis and achieve better hemocompatibility. Whilst driveline infection, right heart failure and arrhythmias have been recognised as LVAD-related complications, this paper focuses on complications related to pump thrombosis, especially blood coagulopathy in detail and potential strategies to mitigate this complication. Furthermore, it also discusses the LVAD implantation techniques and their anatomical challenges.

Dental Implant Healing Screws as Temporary Oral Drug Delivery Systems for Decrease of Infections in the Area of the Head and Neck

Background

Periimplantitis is continuously one of major threats for the uneventful functioning of dental implants. Current approaches of drug delivery systems are being more commonly implemented into oral- and maxillofacial biomaterials in order to decrease the risk of implant failure due to bacterial infection. Silver nanoparticles and their compounds have been proven in eradicating oral bacteria responsible for peri-implant infections. Nevertheless, their evaluation as coating for implant abutments has not been extensively evaluated so far. This article describes a novel coating consisting of zinc oxide (ZnO) and silver (Ag) nanoparticles (NPs). This coating was used to modify healing abutments that could be used as drug delivery systems in oral implantology.

Materials and Method

Nanoparticles with a ZnO + 0.1% Ag composition were produced by microwave solvothermal synthesis and then incorporated into the surface of titanium healing abutments by high-power ultrasonic deposition. Surface morphology, roughness, wettability were evaluated. Ability of biofilm formation inhibition was tested against S. mutans, S. oralis, S. aureus and E. coli.

Results

ZnO+0.1%Ag NPs were sufficiently deposed on the surface of the abutments creating nanostructured coating which increased surface roughness and decreased wettability. Modified abutments significantly decreased bacterial biofilm formation. Bacteria present in SEM studies were unlikely to settle and replicate on the experimental abutments as their cells were rounded, insufficiently spread on the surface and covered with released NPs.

Conclusion

Experimental nanostructured abutments were easily manufactured by high-power ultrasonic deposition and provided significant antibacterial properties. Such biomaterials could be used as temporary drug delivery abutments for prevention and treatment of intra- and extraoral peri-implant infections in the area of the head and neck.

Laser-Assisted Nanotexturing and Silver Immobilization on Titanium Implant Surfaces to Enhance Bone Cell Mineralization and Antimicrobial Properties

Despite the great advancement and wide use of titanium (Ti) and Ti-based alloys in different orthopedic implants, device-related infections remain the major complication in modern orthopedic and trauma surgery. Most of these infections are often caused by both poor antibacterial and osteoinductive properties of the implant surface. Here, we have demonstrated a facile two-step laser nanotexturing and immobilization of silver onto the titanium implants to improve both cellular integration and antibacterial properties of Ti surfaces. The required threshold laser processing power for effective nanotexturing and osseointegration was systematically determined by the level of osteoblast cells mineralized on the laser nanotextured Ti (LN-Ti) surfaces using a neodymium-doped yttrium aluminum garnet laser (Nd:YAG, wavelength of 1.06 μm). Laser processing powers above 24 W resulted in the formation of hierarchical nanoporous structures (average pore 190 nm) on the Ti surface with a 2.5-fold increase in osseointegration as compared to the pristine Ti surface. Immobilization of silver nanoparticles onto the LN-Ti surface was conducted by dip coating in an aqueous silver ionic solution and subsequently converted to silver nanoparticles (AgNPs) by using a low power laser-assisted photocatalytic reduction process. Structural and surface morphology analysis via XRD and SEM revealed a uniform distribution of Ag and the formation of an AgTi-alloy interface on the Ti surface. The antibacterial efficacy of the LN-Ti with laser immobilized silver (LN-Ti/LI-Ag) was tested against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The LN-Ti/LI-Ag surface was observed to have efficient and stable antimicrobial properties for over 6 days. In addition, it was found that the LN-Ti/LI-Ag maintained a cytocompatibility and bone cell mineralization property similar to the LN-Ti surface. The differential toxicity of the LN-Ti/LI-Ag between bacterial and cellular species qualifies this approach as a promising candidate for novel rapid surface modification of biomedical metal implants.

Biocompatible Materials for Orbital Wall Reconstruction-An Overview

The reconstruction of an orbit after complex craniofacial fractures can be extremely demanding. For satisfactory functional and aesthetic results, it is necessary to restore the orbital walls and the craniofacial skeleton using various types of materials. The reconstruction materials can be divided into autografts (bone or cartilage tissue) or allografts (metals, ceramics, or plastic materials, and combinations of these materials). Over time, different types of materials have been used, considering characteristics such as their stability, biocompatibility, cost, safety, and intraoperative flexibility. Although the ideal material for orbital reconstruction could not be unanimously identified, much progress has been achieved in recent years. In this article, we summarise the advantages and disadvantages of each category of reconstruction materials. We also provide an update on improvements in material properties through various modern processing techniques. Good results in reconstructive surgery of the orbit require both material and technological innovations.

Preparation and characterization of TiO 2 ‐coated polymerization of methyl methacrylate (PMMA) for biomedical applications: In vitro study

Low surface energy and hydrophobicity of polymethyl methactylate (PMMA) are the main disadvantages of this biomaterial. The aim of this study was to investigate the effects of a new coating process on the surface characteristics and properties of PMMA. A combination of temperature and pressure was used for deposition of titanium dioxide (TiO₂) on the surface of PMMA. The PMMA coated with TiO₂ thin films and prepared by sputtering and non-coated PMMA were considered as control groups. The surface wettability, functional group, and roughness were determined by contact angle measurement, Fourier transform Infrared spectroscopy (FTIR), and 3D laser scanning digital microscopy, respectively. The flexural strength of coated and non-coated samples was measured using three-point bending test. The cell proliferation, attachment, and viability were determined using 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide, live and dead assay, scanning electron microscope (SEM), and DAPI (4',6-diamidino-2-phenylindole) staining. The antifungal activity of TiO₂ was also determined by examining the biofilm attachment of Candida albicans. The obtained results showed that TiO₂ was successfully coated on PMMA. The contact angle measurement shows a significant increase of hydrophilicity in TiO₂-coated PMMA. FTIR and roughness analysis revealed no loss of TiO₂ from coated specimens following sonication. The cell viability after 7 days culturing on TiO2-coated specimens was more than the cell viability on the control groups. SEM images and DAPI staining showed that the total number of the cells increased after 7 days of seeding on TiO₂-coated group, whereas it decreased gradually in both control groups. C. albicans attachment also decreased by 63% to 77% on the coated PMMA surface. Overall, this research suggested a new way for developing surface energy of PMMAs for biomedical applications.

Hybrid Surface Nanostructures Using Chemical Vapor Deposition and Colloidal Self-Assembled Patterns for Human Mesenchymal Stem Cell Culture—A Preliminary Study

Surface coatings are critical in biomaterials and biomedical devices. Chemical vapor deposition (CVD) is a well-known technology for the generation of thin films on a surface. However, the granular structures produced using CVD are rare. Recently, we used PPX-C, an excellent insulating material, for granular structure coating using CVD. Colloidal self-assembly is also a well-established method to generate granular structures named colloidal self-assembled patterns (cSAPs). In this study, we combined these two technologies to generate hierarchical granular structures and tested the biophysical effect of these hybrid surfaces on human bone marrow mesenchymal stem cells (hBMSCs). Two CVD-derived granular structures were made using water or glycerin droplets (i.e., CVD or GlyCVD surfaces). Water drops generate porous particles, while glycerin drops generate core–shell particles on the surface. These particles were dispersed randomly on the surface with sizes ranging from 1 to 20 μm. These CVD surfaces were hydrophobic (WCA ~ 80–110 degrees). On the other hand, a binary colloidal crystal (BCC), one type of cSAPs, composed of 5 μm Si and 400 nm carboxylated polystyrene (PSC) particles, had a close-packed structure and a hydrophilic surface (WCA ~ 45 degrees). The hybrid surfaces (i.e., CVD-BCC and GlyCVD-BCC) were smooth (Ra ~ 1.1–1.5 μm) and hydrophilic (WCA ~ 50 degrees), indicating a large surface coverage of BCC dominating the surface property. The hybrid surfaces were expected to be slightly negatively charged due to naturally charged CVD particles and negatively charged BCC particles. Cell adhesion was reduced on the hybrid surfaces, leading to an aggregated cell morphology, without reducing cell activity, compared to the flat control after 5 days. qPCR analysis showed that gene expression of type II collagen (COL2) was highly expressed on the GlyCVD-BCC without chemical induction after 3 and 14 days compared to the flat control. This proof-of-concept study demonstrates the potential of combining two technologies to make hybrid structures that can modulate stem cell attachment and differentiation.

Nanoscale Topographical Effects on the Adsorption Behavior of Bone Morphogenetic Protein-2 on Graphite

The interaction between bone morphogenetic protein-2 (BMP-2) and the surface of biomaterials is essential for the restoration of bone and cartilage tissue, inducing cellular differentiation and proliferation. The properties of the surface, including topology features, regulate the conformation and bioactivity of the protein. In this research, we investigated the influence of nanopatterned surfaces on the interaction of a homodimer BMP-2 with graphite material by combining molecular dynamics (MD) and steered molecular dynamics (SMD) simulations. The graphite substrates were patterned as flat, linear grating, square, and circular profiles in combination with BMP-2 conformation in the side-on configuration. Ramachandran plots for the wrist and knuckle epitopes indicated no steric hindrances and provided binding sites to type I and type II receptors. Results showed two optimal patterns that increased protein adsorption of the lower monomer while preserving the secondary structure and leaving the upper monomer free to interact with the cells. Charged residues arginine and lysine and polar residues histidine and tyrosine were the main residues responsible for the strong interaction with the graphite surface. This research provides new molecular-level insights to further understand the mechanisms underlying protein adsorption on nanoscale patterned substrates.

An Atomistic Investigation of Adsorption of Bone Morphogenetic Protein-2 on Gold with Nanoscale Topographies

Nanoscale surface topographies mediated with biochemical cues influence the differentiation of stem cells into different lineages. This research focuses on the adsorption behavior of bone morphogenetic protein (BMP-2) on nanopatterned gold substrates, which can aid in the differentiation of bone and cartilage tissue constructs. The gold substrates were patterned as flat, pillar, linear grating, and linear-grating deep based, and the BMP-2 conformation in end-on configuration was studied over 20 ns. The linear grating deep substrate pattern had the highest adsorption energy of around 125 kJ/mol and maintained its radius of gyration of 18.5 Å, indicating a stable adsorption behavior. Secondary structures including α-helix and β-sheet displayed no denaturation, and thus, the bioavailability of the BMP-2, for the deep linear-grating pattern. Ramachandran plots for the wrist and knuckle epitopes indicated no steric hindrances and provided binding sites to type I and type II receptors. The deep linear-grating substrate had the highest number of contacts (88 atoms) within 5 Å of the gold substrate, indicating its preferred nanoscale pattern choice among the substrates considered. This research provides new insights into the atomistic adsorption of BMP-2 on nanoscale topographies of a gold substrate, with applications in biomedical implants and regenerative medicine.

Surface PEGylation via Ultrasonic Spray Deposition for the Biofouling Mitigation of Biomedical Interfaces

Air plasma and spray technology are common methods for surface modification. In this study, air plasma is used to generate hydroxyl groups on various material surfaces. Then random copolymers of styrene and ethylene glycol methacrylate (PS-r-PEGMA) are spray-coated to achieve coating densities ranging between 0.1 and 0.6 mg/cm². PS₅₀-r-PEGMA₅₀ led to the best overall antifouling properties, while a coating density of 0.3 mg/cm² was enough to significantly reduce biofouling. This surface modification technique enabled efficient modification of a wide range of materials and biofouling reduction by at least 75% on polymeric surfaces (polystyrene, polyvinylidene fluoride, poly(tetrafluoroethylene), polydimethylsiloxane), metallic surfaces (steel, titanium alloy), or ceramic surface (glass). Applied to the modification of well plate used for blood-typing, this antifouling modification permitted to greatly increase the signal sensitivity (×4).

Polydopamine treatment of chitosan nanofibers for the conception of osteoinductive scaffolds for bone reconstruction

We report the influence of treatment time of electrospun chitosan nanofibers (CHT NFs) in dopamine hydrochloride bath (2 mg.mL^-1 in 10 mM Tris buffer, pH 8.5) on the extent of the polydopamine (pDA) coating on NFs surface. The reaction was characterized by FTIR and SEM analysis and the cytocompatibility of the scaffolds toward MT3C3-E1 cells was assessed. Biomimetic deposition of hydroxyapatite (HA) in 1.5xSBF batch was investigated by SEM-EDS and XRD. Samples treated in dopamine bath during 2 h promoted the structural stability of NFs in PBS, provided optimal cytocompatibility and induced the in vitro biomineralization from 6 days in 1.5xSBF. The XRD and SEM-EDS investigations confirmed formation of spherical-shaped particles composed of apatitic phase. Finally, this study shows that these NFs-pDA scaffolds prepared in the optimal experimental conditions defined here are promising candidates for application as osteoinductive scaffolds for bone regeneration applied to orthopedic and dental applications.

Recent developments on bismuth oxyhalide-based functional nanomaterials for biomedical applications

Multifunctional bismuth oxyhalide (BiOX, X = F, Cl, Br, and I) nanomaterials have great potential advantages in medical diagnostic and therapeutic applications. Pure BiOX nanomaterials have some limitations such as...