Vascular cell behavior on heparin-like polymers modified silicone surfaces: The prominent role of the lotus leaf-like topography

Endothelium-Inspired Hemocompatible Silicone Surfaces: An Elegant Balance between Antifouling Properties and Endothelial Cell Selectivity

To address the adverse reactions caused by the implantation of blood-contacting materials, researchers have developed different strategies, of which mimicking multiple key features of endothelial cells is the most effective. However, simultaneously immobilizing multiple chemical components on a single material surface and maintaining the effects of individual components are challenging. In this work, endothelium-mimicking silicone surfaces were developed by incorporating the antifouling polymer poly(oligo(ethylene glycol) methacrylate), the glycosaminoglycan analog poly(sodium 4-vinyl-benzenesulfonate) and a nitric oxide catalyst (selenocystamine dihydrochloride). Through the rational regulation of multiple chemical components, the surfaces harmoniously resisted nonspecific protein adsorption, platelet adhesion and activation and smooth muscle cell hyperproliferation while promoting endothelial cell proliferation and migration. The coculture experiment with HUVECs and HUVSMCs showed that the optimum selectivity of HUVECs/HUVSMCs was ∼1.7. This work contributes insight into the control of antifouling properties and endothelial selectivity, providing a new avenue for the development of blood-contacting materials.

Endothelium-Mimicking Materials: A "Rising Star" for Antithrombosis

The advancement of antithrombotic materials has significantly mitigated the thrombosis issue in clinical applications involving various medical implants. Extensive research has been dedicated over the past few decades to developing blood-contacting materials with complete resistance to thrombosis. However, despite these advancements, the risk of thrombosis and other complications persists when these materials are implanted in the human body. Consequently, the modification and enhancement of antithrombotic materials remain pivotal in 21st-century hemocompatibility studies. Previous research indicates that the healthy endothelial cells (ECs) layer is uniquely compatible with blood. Inspired by bionics, scientists have initiated the development of materials that emulate the hemocompatible properties of ECs by replicating their diverse antithrombotic mechanisms. This review elucidates the antithrombotic mechanisms of ECs and examines the endothelium-mimicking materials developed through single, dual-functional and multifunctional strategies, focusing on nitric oxide release, fibrinolytic function, glycosaminoglycan modification, and surface topography modification. These materials have demonstrated outstanding antithrombotic performance. Finally, the review outlines potential future research directions in this dynamic field, aiming to advance the development of antithrombotic materials.

Balancing functions of antifouling, nitric oxide release and vascular cell selectivity for enhanced endothelialization of assembled multilayers

Surface endothelialization is a promising way to improve the hemocompatibility of biomaterials. However, current surface endothelialization strategies have limitations. For example, various surface functions are not well balanced, leading to undesirable results, especially when multiple functional components are introduced. In this work, a multifunctional surface was constructed by balancing the functions of antifouling, nitric oxide (NO) release and endothelial cell promotion via layer-by-layer (LBL) self-assembly. Poly(sodium p-styrenesulfonate-co-oligo(ethylene glycol) methacrylate) (negatively charged) and polyethyleneimine (positively charged) were deposited on silicon substrates to construct multilayers by LBL self-assembly. Then, organic selenium, which has a NO-releasing function, and the cell-adhesive peptide Gly-Arg-Glu-Asp-Val-Tyr, which selectively promotes endothelial cells, were introduced on the assembled multilayers. Poly(oligo(ethylene glycol) methacrylate) is a hydrophilic component for antifouling properties, and poly(sodium p-styrenesulfonate) is a heparin analog that provides negative charges. By modulating the contents of poly(oligo(ethylene glycol) methacrylate) and poly(sodium p-styrenesulfonate) in the copolymers, the NO release rates catalyzed by the modified surfaces were regulated. Moreover, the behaviors of endothelial cells and smooth muscle cells on modified surfaces were well controlled. The optimized surface strongly promoted endothelial cells and inhibited smooth muscle cells to achieve endothelialization effectively.

Fabrication and Temporal Dependency Osteogenic Regulation of Dual-Scale Hierarchical Microstructures on Medical Metal Surface

The structural characteristics at the interface of bone implants can guide biological regulation. In this study, a dual-scale hierarchical microstructure is proposed and customized using hybrid machining to achieve temporal dependency osteogenic regulation. It is observed that osteoblasts induced by dual-scale hierarchical structure exhibit adequate protrusion development and rapid cell attachment through the modulation of mechanical forces in the cell growth environment, and further promot the upregulation of the cell membrane receptor PDGFR-α, which is related to cell proliferation. Afterward, transcriptomic analysis reveals that during the differentiation stage, the DSH structure regulates cellular signaling cascades primarily through integrin adhesion mechanisms and then accelerates osteogenic differentiation by activating the TGF-β pathway and cAMP signaling pathway. Furthermore, the calcium nodules are preferentially deposited within the lower honeycomb-like channels, thereby endowing the proposed dual-scale hierarchical structure with the potential to induce oriented deposition and improve the long-term stability of the implant.

Chiral ligands and photothermal synergistic effects of inorganic nanoparticles for bacteria-killing

As the drawbacks of antibiotics in treating bacterial infections emerged, physical methods such as near-infrared-activated (NIR-activated) bacterial killing, have attracted great interests for their advantages of no resistance, short action time and few side effects. In this manuscript, NIR-activated bacteria-killing performance of chiral copper sulphide nanoparticles (L-/d-CuS NPs) was investigated using linearly polarized light (LPL) and circularly polarized light (CPL) as illumination sources, respectively. Chiral CuS NPs showed enhanced NIR-activated bacteria-killing effect compared with achiral CuS NPs under the same conditions. Moreover, these chiral CuS NPs showed obvious chirality-related antibacterial effect: the bacterial killing was more efficient under CPL activation, and L- and d-CuS NPs had higher antibacterial efficiency under left circularly polarized light (LCPL) and right circularly polarized light (RCPL), respectively. The possible mechanism of bacteria-killing performance for chiral CuS NPs was discussed in detailed. Photothermal bacteria-killing tests of chiral CuS NPs "sealed" in polydimethylsiloxane (PDMS) demonstrated the individual influence of photothermal effect. These observations in this paper could provide ideas for the potential applications of chiral nanostructures with enhanced photothermal effect in efficient bacterial killing.

Fabrication and Functional Regulation of Biomimetic Interfaces and Their Antifouling and Antibacterial Applications: A Review

Biomimetic synthesis provides potential guidance for the synthesis of bio-nanomaterials by mimicking the structure, properties and functions of natural materials. Behavioral studies of biological surfaces with specific micro/nano structures are performed to explore the interactions of various molecules or organisms with biological surfaces. These explorations provide valuable inspiration for the development of biomimetic surfaces with similar effects. This work reviews some conventional preparation methods and functional modulation strategies for biomimetic interfaces. It aims to elucidate the important role of biomimetic interfaces with antifouling and low-pollution properties that can replace non-environmentally friendly coatings. Thus, biomimetic antifouling interfaces can be better applied in the field of marine antifouling and antimicrobial. In this review, the commonly used fabrication methods for biomimetic interfaces as well as some practical strategies for functional modulation is present in detail. These methods and strategies modify the physical structure and chemical properties of the biomimetic interfaces, thus improving the wettability, adsorption, drag reduction, etc. that they exhibit. In addition, practical applications are presented of various biomimetic interfaces for antifouling and look ahead to potential biomedical applications. By continuously discovering functional surfaces with biomimetic properties and studying their microstructure and macroscopic properties, more biomimetic interfaces will be developed.

Interdisciplinary-Inspired Smart Antibacterial Materials and Their Biomedical Applications

The discovery of antibiotics has saved millions of lives, but the emergence of antibiotic-resistant bacteria has become another problem in modern medicine. To avoid or reduce the overuse of antibiotics in antibacterial treatments, stimuli-responsive materials, pathogen-targeting nanoparticles, immunogenic nano-toxoids, and biomimetic materials are being developed to make sterilization better and smarter than conventional therapies. The common goal of smart antibacterial materials (SAMs) is to increase the antibiotic efficacy or function via an antibacterial mechanism different from that of antibiotics in order to increase the antibacterial and biological properties while reducing the risk of drug resistance. The research and development of SAMs are increasingly interdisciplinary because new designs require the knowledge of different fields and input/collaboration from scientists in different fields. A good understanding of energy conversion in materials, physiological characteristics in cells and bacteria, and bactericidal structures and components in nature are expected to promote the development of SAMs. In this review, the importance of multidisciplinary insights for SAMs is emphasized, and the latest advances in SAMs are categorized and discussed according to the pertinent disciplines including materials science, physiology, and biomimicry.

Surface modification of polydimethylsiloxane by the cataractous eye protein isolate

Polydimethylsiloxane (PDMS), even though widely used in microfluidic applications, its hydrophobic nature restricts its utility in some cases. To address this, PDMS may be used in conjunction with a hydrophilic material. Herein, the PDMS surface is modified by plasma treatment followed by cross-linking with the cataractous eye protein isolate (CEPI). CEPI-PDMS composites are prepared at three pH and the effects of CEPI on the chemical, physical, and electrical properties of PDMS are extensively investigated. The cross-linking between PDMS and the protein are confirmed by FTIR, and the contact angle measurements indicate the improved hydrophilic nature of the composite films as compared to PDMS. Atomic Force Microscopy results demonstrate that the surface roughness is enhanced by the incorporation of the protein and is a function of the pH. The effective elastic modulus of the composites is improved by the incorporation of protein into the PDMS matrix. Measurements of the dielectric properties of these composites indicate that they behave as capacitors at lower frequency range while demonstrating resistive characteristics at higher frequency. These composites provide preliminary ideas in developing flexible devices for potential applications in diverse areas such as energy storage materials, and thermo-elective wireless switching devices.

Regulating cell behavior via regional patterned distribution of heparin-like polymers

Molecular patterning on biomaterial surfaces is an effective strategy to regulate biomaterial properties. Among the specific molecules, due to their biological functions, such as regulating cell behavior, heparin-like polymers (HLPs) have attracted much attention. In this study, HLP-distributed regional patterned surfaces (300 μm diameter circular array) were prepared by the combination of visible light-induced graft polymerization, transfer imprinting, and self-assembly to regulate the behavior of human umbilical vein endothelial cells (HUVECs) and human umbilical vein smooth muscle cells (HUVSMCs). The introduction of the regional pattern on HLP-modified surfaces enhanced the promotion effect of sulfonate-containing polymer (pSS) and sulfonate-, and glyco-containing copolymer (pS-co-pM), and slightly weakened the inhibition effect of glyco-containing polymer (pMAG) on the growth of HUVECs and HUVSMCs. Compared with flat surfaces, it was found that the unmodified regional patterned surfaces inhibit the spreading of HUVECs and HUVSMCs, while significantly promoting the spreading of HUVECs and HUVSMCs on all the HLP-distributed regional patterned surfaces. The patterned surface modified with pS-co-pM had the highest average spread area of HUVECs (∼10,554 μm2), which was 193 % higher than that of the unmodified flat surface. This trend was somewhat related to surface VEGF adsorption. The combination of regional divisive patterns and different HLP distributions enriched the potential of further exploring the influences of HLP chemical distributions and complex surface environments on cell-material interactions.

Replication of natural surface topographies to generate advanced cell culture substrates

Surface topographies of cell culture substrates can be used to generate in vitro cell culture environments similar to the in vivo cell niches. In vivo, the physical properties of the extracellular matrix (ECM), such as its topography, provide physical cues that play an important role in modulating cell function. Mimicking these properties remains a challenge to provide in vitro realistic environments for cells. Artificially generated substrates' topographies were used extensively to explore this important surface cue. More recently, the replication of natural surface topographies has been enabling to exploration of characteristics such as hierarchy and size scales relevant for cells as advanced biomimetic substrates. These substrates offer more realistic and mimetic environments regarding the topographies found in vivo. This review will highlight the use of natural surface topographies as a template to generate substrates for in-vitro cell culture. This review starts with an analysis of the main cell functions that can be regulated by the substrate's surface topography through cell-substrate interactions. Then, we will discuss research works wherein substrates for cell biology decorated with natural surface topographies were used and investigated regarding their influence on cellular performance. At the end of this review, we will highlight the advantages and challenges of the use of natural surface topographies as a template for the generation of advanced substrates for cell culture.

Experimental and fluid flow simulation studies of laser-electrochemical hybrid manufacturing of micro-nano symbiotic superamphiphobic surfaces

Micro-nano symbiotic superamphiphobic surfaces can prevent liquids from adhering to metal surfaces and, as a result, improve their corrosion resistance, self-cleaning performance, pollution resistance, and ice resistance. However, the fabrication of stable and controllable micro-nano symbiotic superamphiphobic structures on metal surfaces commonly used in industry remains a significant challenge. In this study, a laser-electrochemical hybrid subtractive-additive manufacturing method was proposed and developed for preparing copper superamphiphobic surfaces. Both experimental and fluid simulation studies were carried out. Utilizing this novel hybrid method, the controllable preparation of superamphiphobic micro-nano symbiotic structures was realized. The experimental results showed that the prepared surfaces had excellent superamphiphobic properties following subsequent modification with low surface energy substances. The contact angles of water droplets and oil droplets on the surface following electrodeposition treatment reached values of 161 ± 4° and 151 ± 4°, respectively, which showed that the prepared surface possessed perfect superamphiphobicity. Both the fabrication method and the test results provided useful insights for the preparation of stable and controllable superamphiphobic structures on metal surfaces in the future.

A composite membrane with microtopographical morphology to regulate cellular behavior for improved tissue regeneration

Tissue engineering scaffolds with specific surface topographical morphologies can regulate cellular behaviors and promote tissue repair. In this study, poly lactic(co-glycolic acid) (PLGA)/wool keratin composite guided tissue regeneration (GTR) membranes with three types of microtopographies (three groups each of pits, grooves and columns, thus nine groups in total) were prepared. Then, the effects of the nine groups of membranes on cell adhesion, proliferation and osteogenic differentiation were examined. The nine different membranes had clear, regular and uniform surface topographical morphologies. The 2 µm pit-structured membrane had the best effect on promoting the proliferation of bone marrow mesenchymal stem cells (BMSCs) and periodontal ligament stem cells (PDLSCs), while the 10 µm groove-structured membrane was the best for inducing osteogenic differentiation of BMSCs and PDLSCs. Then, we investigated the ectopic osteogenic, guided bone tissue regeneration and guided periodontal tissue regeneration effects of the 10 µm groove-structured membrane combined with cells or cell sheets. The 10 µm groove-structured membrane/cell complex had good compatibility and certain ectopic osteogenic effects, and the 10 µm groove-structured membrane/cell sheet complex promoted better bone repair and regeneration and periodontal tissue regeneration. Thus, the 10 µm groove-structured membrane shows potential to treat bone defects and periodontal disease. STATEMENT OF SIGNIFICANCE: PLGA/wool keratin composite GTR membranes with microcolumn, micropit and microgroove topographical morphologies were prepared by dry etching technology and the solvent casting method. The composite GTR membranes had different effects on cell behavior. The 2 µm pit-structured membrane had the best effect on promoting the proliferation of rabbit BMSCs and PDLSCs and the 10 µm groove-structured membrane was the best for inducing the osteogenic differentiation of BMSCs and PDLSCs. The combined application of a 10 µm groove-structured membrane and PDLSC sheet can promote better bone repair and regeneration as well as periodontal tissue regeneration. Our findings may have significant potential for guiding the design of future GTR membranes with topographical morphologies and clinical applications of the groove-structured membrane/cell sheet complex.

Effect of Structural Elements of Heparin-Mimicking Polymers on Vascular Cell Distribution and Functions: Chemically Homogeneous or Heterogeneous?

Heparin-mimicking polymers (HMPs) are artificially synthesized alternatives to heparin with comparable regulatory effects on protein adsorption and cell behavior. By introducing two major structural elements of HMPs (sulfonate- and glyco-containing units) to different areas of material surfaces, heterogeneous surfaces patterned with different HMPs and homogeneous surfaces patterned with the same HMPs can be obtained. In this work, heterogeneous HMP-patterned poly(dimethylsiloxane) (PDMS) surfaces with sulfonate-containing polySS (pS) and glyco-containing polyMAG (pM) distributed in circular patterns (with a diameter of 300 μm) were prepared (S-M and M-S). Specifically, pS and pM were distributed inside and outside the circles on S-M, respectively, and exchanged their distribution on M-S. Homogeneous HMP-patterned silicone surfaces (SM-SM) where sulfonate- and glyco-containing poly(SS-co-MAG) (pSM) were distributed uniformly were prepared. Vascular cells showed interestingly different behaviors between chemically homogeneous and heterogeneous surfaces. They tended to grow in the sulfonate-modified area on S-M and M-S and were distributed uniformly on SM-SM. Compared with M-S, S-M showed a better promoting effect on the growth of vascular cells. Among all the samples, SM-SM exhibited the highest proliferation density and an optimum spreading state of vascular cells, as well as the highest human umbilical vein endothelial cell (HUVEC) viability (∼99%) and relatively low human umbilical vein smooth muscle cell (HUVSMC) viability (∼72%). By heterogeneous or homogeneous patterning with different structural elements of HMPs, the modified silicone surfaces spatially guided vascular cell distribution and functions. This strategy provides a new surface engineering approach to the study of cell-HMP interactions.

A preliminary study on surface bioactivation of polyaryletherketone by UV-grafting with PolyNaSS: influence on osteogenic and antibacterial activities

Polyaryletherketone (PAEK) has good biocompatibility and mechanical properties and thus may have great potential in the fields of reparative medicine and bone intervention. In this study, the key representative PAEKs, polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), were modified by UV grafting with sodium polystyrene sulfonate (polyNaSS) to improve their biocompatibility. Toluidine blue staining and Fourier transform infrared spectroscopic analyses showed that sulfonic acid groups were successfully introduced into PAEK, and the hydrophilicity and protein adsorption capacity of the materials were enhanced in a concentration-dependent manner. The effects of the grafted polyNaSS on osteoinduction and antibacterial properties of PAEK were analyzed in detail. We found that polyNaSS enhanced the viability, alkaline phosphatase activity, calcium mineral deposition, and levels of expression of osteoblast-related genes and proteins of adherent human umbilical cord Wharton's jelly-derived mesenchymal stem cells. In addition, when Escherichia coli, Staphylococcus aureus and Porphyromonas gingivalis were incubated with the materials, bacterial colony counting revealed that grafting of polyNaSS onto PAEK led to more potent inhibition of bacterial adhesion, and polyNaSS-grafted PEKK had stronger antibacterial performance than did polyNaSS-grafted PEEK fabricated under the same grafting conditions. These data show that polyNaSS-grafted PAEK, and particularly polyNaSS-grafted PEKK, may be useful as orthopedic and dental implant materials.

Vascular cell behavior on glycocalyx-mimetic surfaces: Simultaneous mimicking of the chemical composition and topographical structure of the vascular endothelial glycocalyx

The endothelial glycocalyx is a carbohydrate-rich layer overlying the outermost surface of endothelial cells. It mediates intercellular interactions by specific chemical compositions (e.g., proteoglycans containing glycosaminoglycan (GAG) side chains) and micro/nanotopography. Inspired by the endothelial glycocalyx, we fabricated a series of glycocalyx-mimetic surfaces with tunable chemical compositions (GAG-like polymers with different functional units) and topographical structures (micro/nanopatterns with pillars different in size). The combination of micro/nanopatterns and GAG-like polymers was flexibly and precisely controlled by replica molding using silicon templates (Si templates) and visible light-initiated polymerization. Human umbilical vein endothelial cells (HUVECs) and human umbilical vein smooth muscle cells (HUVSMCs) were suppressed on surfaces modified with polymers of 2-methacrylamido glucopyranose (MAG) but promoted on surfaces modified with polymers of sodium 4-vinyl-benzenesulfonate (SS) and copolymers of SS and MAG. Surface micro/nanopatterns showed highly complicated effects on surfaces grafted with different GAG-like polymers. Moreover, the spread of HUVSMCs was highly promoted on all flat/patterned surfaces containing sulfonate units, and the elongation effect was stronger on surfaces with smaller pillars. On all the flat/patterned surfaces modified with GAG-like polymers, the adsorption of human vascular endothelial growth factor (VEGF) and human basic fibroblast growth factor (bFGF) was improved, and the amount of VEGF and bFGF absorbed on patterned surfaces containing sulfonate units decreased with pattern dimensions. The decreasing trend of VEGF and bFGF adsorption was in accordance with HUVEC density, suggesting that glycocalyx-mimetic surfaces influence the adsorption of VEGF and bFGF and further influence the growth behavior of vascular cells.

Surface Modification Techniques to Produce Micro/Nano-scale Topographies on Ti-Based Implant Surfaces for Improved Osseointegration

Titanium and titanium alloys are used as artificial bone substitutes due to the good mechanical properties and biocompatibility, and are widely applied in the treatment of bone defects in clinic. However, Pure titanium has stress shielding effect on bone, and the effect of titanium-based materials on promoting bone healing is not significant. To solve this problem, several studies have proposed that the surface of titanium-based implants can be modified to generate micro or nano structures and improve mechanical properties, which will have positive effects on bone healing. This article reviews the application and characteristics of several titanium processing methods, and explores the effects of different technologies on the surface characteristics, mechanical properties, cell behavior and osseointegration. The future research prospects in this field and the characteristics of ideal titanium-based implants are proposed.

Bioinspired Topographic Surface Modification of Biomaterials

Physical surface modification is an approach that has been investigated over the last decade to reduce bacterial adhesion and improve cell attachment to biomaterials. Many techniques have been reported to modify surfaces, including the use of natural sources as inspiration to fabricate topographies on artificial surfaces. Biomimetics is a tool to take advantage of nature to solve human problems. Physical surface modification using animal and vegetal topographies as inspiration to reduce bacterial adhesion and improve cell attachment has been investigated in the last years, and the results have been very promising. However, just a few animal and plant surfaces have been used to modify the surface of biomaterials with these objectives, and only a small number of bacterial species and cell types have been tested. The purpose of this review is to present the most current results on topographic surface modification using animal and plant surfaces as inspiration to modify the surface of biomedical materials with the objective of reducing bacterial adhesion and improving cell behavior.

Micro/Nanopatterned Superhydrophobic Surfaces Fabrication for Biomolecules and Biomaterials Manipulation and Analysis

Superhydrophobic surfaces display an extraordinary repulsion to water and water-based solutions. This effect emerges from the interplay of intrinsic hydrophobicity of the surface and its morphology. These surfaces have been established for a long time and have been studied for decades. The increasing interest in recent years has been focused towards applications in many different fields and, in particular, biomedical applications. In this paper, we review the progress achieved in the last years in the fabrication of regularly patterned superhydrophobic surfaces in many different materials and their exploitation for the manipulation and characterization of biomaterial, with particular emphasis on the issues affecting the yields of the fabrication processes and the quality of the manufactured devices.

Enhanced hydrophilicity and anticoagulation of polysulfone materials modified via dihydroxypropyl, sulfonic groups and chitosan

A novel modified polysulfone (PSF) is successfully prepared for hemodialysis by grafting with a well-defined heparin-like polymer, sulfonated dihydroxypropyl chitosan (SDHPCS), which is obtained in proper sequence via alkalization of chitosan, etherification and sulfonation. PSF is modified via chloroacetyl chloride, and then, the chloroacylated polysulfone (CAPSF) with pristine PSF is transformed into CAPSF/PSF blend membrane via the phase inversion, followed introducing amino group into CAPSF on the surface and taking glutaraldehyde as bridge between modified PSF membrane and SDHPCS. The result of ¹H NMR spectrum of prepared CAPSF indicates that the degree of the substitution of chloroacetyl group. The SEM, EDS mapping, FTIR and XPS show that SDHPCS-g-PSF membranes are successfully prepared. The hydrophilicity of the membrane modified by SDHPCS is improved obviously, and the contact angle remarkably reduced from 87 ° to below 45°, exhibiting much better hydrophilicity. The hemocompatibility characterizations including BSA adsorption, Plasma recalcification time (PRT), hemolysis ratio (HR), activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) also certificates that SDHPCS-g-PSF possesses lower BSA adsorption and enhanced blood compatibility.