Cell adhesion on a POEGMA-modified topographical surface

3D-printed mesoporous bioactive glass/GelMA biomimetic scaffolds for osteogenic/cementogenic differentiation of periodontal ligament cells

Integrated regeneration of periodontal tissues remains a challenge in current clinical applications. Due to the tunable physical characteristics and the precise control of the scaffold microarchitecture, three-dimensionally (3D) printed gelatin methacryloyl (GelMA)-based scaffold has emerged as a promising strategy for periodontal tissue regeneration. However, the optimization of the printing biomaterial links the formulation and the relationship between the composition and structures of the printed scaffolds and their comprehensive properties (e.g. mechanical strength, degradation, and biological behaviors) remains unclear. Here, in this work, a novel mesoporous bioactive glass (BG)/GelMA biomimetic scaffold with a large pore size (∼300 μm) was developed by extrusion-based 3D printing. Our results showed that the incorporation of mesoporous bioactive glass nanoparticles (BG NPs) significantly improved shape fidelity, surface roughness, and bioactivity of 3D-printed macroporous GelMA scaffolds, resulting in the enhanced effects on cell attachment and promoting osteogenic/cementogenic differentiation in human periodontal ligament cells. The excellent maintenance of the macropore structure, the visibly improved cells spreading, the release of bioactive ions (Si4+, Ca2+), the upregulation of gene expressions of osteogenesis and cementogensis, and the increase in alkaline phosphatase (ALP) activity and calcium nodules suggested that BG NPs could endow GelMA-based scaffolds with excellent structural stability and the ability to promote osteogenic/cementogenic differentiation. Our findings demonstrated the great potential of the newly formulated biomaterial inks and biomimetic BG/GelMA scaffolds for being used in periodontal tissue regeneration and provide important insights into the understanding of cell-scaffold interaction in promoting the regeneration of functional periodontal tissues.

Characterization of Macrophage and Cytokine Interactions with Biomaterials Used in Negative-Pressure Wound Therapy

Macrophages are innate immune cells that help wounds heal. Here, we study the potential immunomodulatory effects of negative-pressure wound therapy (NPWT) materials on the macrophage inflammatory response. We compared the effects of two materials, Granufoam™ (GF) and Veraflo Cleanse™ (VC), on macrophage function in vitro. We find that both materials cause reduced expression of inflammatory genes, such as TNF and IL1B, in human macrophages stimulated with bacterial lipopolysaccharide (LPS) and interferon-gamma (IFNγ). Relative to adherent glass control surfaces, VC discourages macrophage adhesion and spreading, and may potentially sequester LPS/IFNγ and cytokines that the cells produce. GF, on the other hand, was less suppressive of inflammation, supported macrophage adhesion and spreading better than VC, and sequestered lesser quantities of LPS/IFNγ in comparison to VC. The control dressing material cotton gauze (CT) was also immunosuppressive, capable of TNF-α retention and LPS/IFNγ sequestration. Our findings suggest that NPWT material interactions with cells, as well as soluble factors including cytokines and LPS, can modulate the immune response, independent of vacuum application. We have also established methodological strategies for studying NPWT materials and reveal the potential utility of cell-based in vitro studies for elucidating biological effects of NPWT materials.

Influence of surface topography on PCL electrospun scaffolds for liver tissue engineering

Severe liver disease is one of the most common causes of death globally. Currently, whole organ transplantation is the only therapeutic method for end-stage liver disease treatment, however, the need for donor organs far outweighs demand. Recently liver tissue engineering is starting to show promise for alleviating part of this problem. Electrospinning is a well-known method to fabricate a nanofibre scaffold which mimics the natural extracellular matrix that can support cell growth. This study aims to investigate liver cell responses to topographical features on electrospun fibres. Scaffolds with large surface depression (2 μm) (LSD), small surface depression (0.37 μm) (SSD), and no surface depression (NSD) were fabricated by using a solvent-nonsolvent system. A liver cell line (HepG2) was seeded onto the scaffolds for up to 14 days. The SSD group exhibited higher levels of cell viability and DNA content compared to the other groups. Additionally, the scaffolds promoted gene expression of albumin, with all cases having similar levels, while the cell growth rate was altered. Furthermore, the scaffold with depressions showed 0.8 MPa higher ultimate tensile strength compared to the other groups. These results suggest that small depressions might be preferred by HepG2 cells over smooth and large depression fibres and highlight the potential for tailoring liver cell responses.

Fabrication and Impact of Fouling-Reducing Temperature-Responsive POEGMA Coatings with Embedded CaCO3 Nanoparticles on Different Cell Lines

In the present work, we have successfully prepared and characterized novel nanocomposite material exhibiting temperature-dependent surface wettability changes, based on grafted brush coatings of non-fouling poly(di(ethylene glycol)methyl ether methacrylate) (POEGMA) with the embedded CaCO3 nanoparticles. Grafted polymer brushes attached to the glass surface were prepared in a three-step process using atom transfer radical polymerization (ATRP). Subsequently, uniform CaCO3 nanoparticles (NPs) embedded in POEGMA-grafted brush coatings were synthesized using biomineralized precipitation from solutions of CaCl2 and Na2CO3. An impact of the low concentration of the embedded CaCO3 NPs on cell adhesion and growth depends strongly on the type of studied cell line: keratinocytes (HaCaT), melanoma (WM35) and osteoblastic (MC3T3-e1). Based on the temperature-responsive properties of grafted brush coatings and CaCO3 NPs acting as biologically active substrate, we hope that our research will lead to a new platform for tissue engineering with modified growth of the cells due to the release of biologically active substances from CaCO3 NPs and the ability to detach the cells in a controlled manner using temperature-induced changes of the brush.

Biophysical restriction of growth area using a monodispersed gold sphere nanobarrier prolongs the mitotic phase in HeLa cells

Homogeneous 83 nm gold nanospheres with a human fibronectin-coated substrate surrounding the cells induce biophysical cues which result in a delay in the mitotic phase of the cell cycle.

En Route to Practicality of the Polymer Grafting Technology: One-Step Interfacial Modification with Amphiphilic Molecular Brushes

Surface modification with polymer grafting is a versatile tool for tuning the surface properties of a wide variety of materials. From a practical point of view, such a process should be readily scalable and transferable between different substrates and consist of as least number of steps as possible. To this end, a cross-linkable amphiphilic copolymer system that is able to bind covalently to surfaces and form permanently attached networks via a one-step procedure is reported here. This system consists of brushlike copolymers (molecular brushes) made of glycidyl methacrylate, poly(oligo(ethylene glycol) methyl ether methacrylate), and lauryl methacrylate, which provide the final product with tunable reactivity and balance between hydrophilicity and hydrophobicity. The detailed study of the copolymer synthesis and properties has been carried out to establish the most efficient pathway to design and tailor this amphiphilic molecular brush system for specific applications. As an example of the applications, we showed the ability to control the deposition of graphene oxide (GO) sheets on both hydrophilic and hydrophobic surfaces using GO modified with the molecular brushes. Also, the capability to tune the osteoblast cell adhesion with the copolymer-based coatings was demonstrated.

Impact of Anti-Biofouling Surface Coatings on the Properties of Nanomaterials and Their Biomedical Applications

Understanding and subsequently controlling non-specific interactions between engineered nanomaterials and biological environment have become increasingly important for further developing and advancing nanotechnology for biomedical applications. Such non-specific interactions, also known as the biofouling effect, mainly associate with the adsorption of biomolecules (such as proteins, DNAs, RNAs, and peptides) onto the surface of nanomaterials and the adhesion or uptake of nanomaterials by various cells. By altering the surface properties of nanomaterials the biofouling effect can lead to in situ changes of physicochemical properties, pharmacokinetics, functions, and toxicity of nanomaterials. This review provides discussions on the current understanding of the biofouling effect, the factors that affect the non-specific interactions associated with biofouling, and the impact of the biofouling effect on the performances and functions of nanomaterials. An overview of the development and applications of various anti-biofouling coating materials to preserve and improve the properties and functions of engineered nanomaterials for intended biomedical applications is also provided.

Multifunctional gold nanoparticle layers for controllable capture and release of proteins

Protein modified functional surfaces have been applied extensively in the field of biomaterials and medicine. Regulation of the amount and activity of proteins on the material surface is always a challenge and a key research issue. A multifunctional micro/nano-composite based surface system for efficient controllable capture and release of proteins is proposed and studied in the present paper. This novel system contains (1) gold nanoparticles (AuNPs) co-modified with an enzyme and poly(methacrylic acid) (PMAA), e.g., AuNP-pyrophosphatase (PPase)-PMAA, as nanostructured protein carriers; (2) gold nanoparticle layers (GNPLs) modified with poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), i.e., GNPL-PDMAEMA, as a micro/nano-structured support platform for surface bioactivity regulation. The capture-release of proteins and the regulation of surface bioactivity in this composite surface system were investigated under different conditions. The results showed that the proposed system is capable of protein capture and release with simple adjustment of the pH value from neutral pH to basic pH. When the pH of the system is stabilized at 7.0, the GNPL-PDMAEMA surface could adsorb plenty of AuNP-PPase-PMAA conjugates and maximum surface bioactivity occurred, but when the pH of the system is adjusted to 10.0, the GNPL-PDMAEMA surface could liberate almost all the AuNP-PPase-PMAA conjugates and thus surface bioactivity disappeared. Meanwhile, by cyclical variations between pH 7.0 and pH 10.0, this surface protein capture/release system could realize recycling and reuse of one certain protein multiple times, a series of proteins acting sequentially in accordance with pre-designed procedures, and a functional combination of multiple proteins. This recyclable multifunctional surface with the capability of protein capture/release has great potential in many applications, such as biomonitoring and biomolecule immobilization.

Dopamine-Triggered One-Step Polymerization and Codeposition of Acrylate Monomers for Functional Coatings

Surface modification has been well recognized as a promising strategy to design and exploit diversified functional materials. However, conventional modification strategies usually suffer from complicated manufacture procedures and lack of universality. Herein, a facile, robust, and versatile approach is proposed to achieve the surface functionalization using dopamine and acrylate monomers via a one-step polymerization and codeposition process. The gel permeation chromatography, proton nuclear magnetic resonance, liquid chromatography-mass spectrometry, and UV-visible spectra results indicate that dopamine possesses the capability of triggering the polymerization of acrylate monomers into high-molecular-weight products, and the inherent adhesive ability of polydopamine can assist the polymerized products to deposit on various substrates. Besides, protein-resistant, antibacterial, and cell adhesion-resistant surfaces can be easily fabricated via the finely designed integration of corresponding acrylate monomers into the codeposition systems. This approach of in situ polymerization and codeposition significantly simplifies the fabrication process and provides more manifold choices for surface modification, which will open a new door for broadening the applications of polydopamine-based coatings.

A comparison study between electrospun polycaprolactone and piezoelectric poly(3-hydroxybutyrate-co-3-hydroxyvalerate) scaffolds for bone tissue engineering

In this study, bone scaffolds composed of polycaprolactone (PCL), piezoelectric poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and a combination of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and silicate containing hydroxyapatite (PHBV-SiHA) were successfully fabricated by a conventional electrospinning process. The morphological, chemical, wetting and biological properties of the scaffolds were examined. All fabricated scaffolds are composed of randomly oriented fibres with diameters from 800nm to 12μm. Fibre size increased with the addition of SiHA to PHBV scaffolds. Moreover, fibre surface roughness in the case of hybrid scaffolds was also increased. XRD, FTIR and Raman spectroscopy were used to analyse the chemical composition of the scaffolds, and contact angle measurements were performed to reveal the wetting behaviour of the synthesized materials. To determine the influence of the piezoelectric nature of PHBV in combination with SiHA nanoparticles on cell attachment and proliferation, PCL (non-piezoelectric), pure PHBV, and PHBV-SiHA scaffolds were seeded with human mesenchymal stem cells (hMSCs). In vitro study on hMSC adhesion, viability, spreading and osteogenic differentiation showed that the PHBV-SiHA scaffolds had the largest adhesion and differentiation abilities compared with other scaffolds. Moreover, the piezoelectric PHBV scaffolds have demonstrated better calcium deposition potential compared with non-piezoelectric PCL. The results of the study revealed pronounced advantages of hybrid PHBV-SiHA scaffolds to be used in bone tissue engineering.

Nanotopography featured polycaprolactone/polyethyleneoxide microfibers modulate endothelial cell response

Among many physical properties, surface nanotopography has been found to strongly affect cell adhesion, migration and other functions. Accurate biological interpretation requires the nanotopography to be presented in a three-dimensional (3D) micro-environment. Herein, immiscible blends of polycaprolactone (PCL)/polyethyleneoxide (PEO) were electrospun into a grounded coagulation bath, resulting in macroporous microfibers with nanotopography featured surfaces. Variations in PCL/PEO ratios enabled tunable surface nanotopographic structures, from longitudinal submicron grooves to transverse nano-lamellae. Chemical composition, crystallinity and quantitative nanomechanical analysis confirmed that the interplay of the two semi-crystalline immiscible polymers and the pairing of miscible solvents/non-solvents in both the electrospinning solution and the bath solution were critical for the formation of the secondary structure. It was found that the nanotopography features promoted the proliferation of human umbilical vein endothelial cells (HUVECs) compared with their smooth film counterparts. An analysis of the cell adhesion related markers, vinculin and phosphorylated focal adhesion kinase (pFAK), further revealed that the nanotopographies enhanced the nascent adhesion complex formation compared with smooth PCL fibers, even in the scaffolds with a high PEO content, which is often considered as a non-adhesive material.

Poly(oligo(ethylene glycol) methyl ether methacrylate) Brushes on High-κ Metal Oxide Dielectric Surfaces for Bioelectrical Environments

Advances in electronics and life sciences have generated interest in "lab-on-a-chip" systems utilizing complementary metal oxide semiconductor (CMOS) circuitry for low-power, portable, and cost-effective biosensing platforms. Here, we present a simple and reliable approach for coating "high-κ" metal oxide dielectric materials with "non-fouling" (protein- and cell-resistant) poly(oligo(ethylene glycol) methyl ether methacrylate (POEGMA) polymer brushes as biointerfacial coatings to improve their relevance for biosensing applications utilizing advanced electronic components. By using a surface-initiated "grafting from" strategy, POEGMA films were reliably grown on each material, as confirmed by ellipsometric measurements and X-ray photoelectron spectroscopy (XPS) analysis. The electrical behavior of these POEGMA films was also studied to determine the potential impact on surrounding electronic devices, yielding information on relative permittivity and breakdown field for POEGMA in both dry and hydrated states. We show that the incorporation of POEGMA coatings significantly reduced levels of nonspecific protein adsorption compared to uncoated high-κ dielectric oxide surfaces as shown by protein resistance assays. These attributes, combined with the robust dielectric properties of POEGMA brushes on high-κ surfaces open the way to incorporate this protein and cell resistant polymer interface into CMOS devices for biomolecular detection in a complex liquid milieu.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

Biomaterials and Culture Technologies for Regenerative Therapy of Liver Tissue

Regenerative approach has emerged to substitute the current extracorporeal technologies for the treatment of diseased and damaged liver tissue. This is based on the use of biomaterials that modulate the responses of hepatic cells through the unique matrix properties tuned to recapitulate regenerative functions. Cells in liver preserve their phenotype or differentiate through the interactions with extracellular matrix molecules. Therefore, the intrinsic properties of the engineered biomaterials, such as stiffness and surface topography, need to be tailored to induce appropriate cellular functions. The matrix physical stimuli can be combined with biochemical cues, such as immobilized functional groups or the delivered actions of signaling molecules. Furthermore, the external modulation of cells, through cocultures with nonparenchymal cells (e.g., endothelial cells) that can signal bioactive molecules, is another promising avenue to regenerate liver tissue. This review disseminates the recent approaches of regenerating liver tissue, with a focus on the development of biomaterials and the related culture technologies.

Hepatitis B plasmonic biosensor for the analysis of clinical serum samples

A plasmonic biosensor for rapid detection of protein biomarkers in complex media is reported. Clinical serum samples were analyzed by using a novel biointerface architecture based on poly[(N-(2-hydroxypropyl) methacrylamide)-co-(carboxybetaine methacrylamide)] brushes functionalized with bioreceptors. This biointerface provided an excellent resistance to fouling even after the functionalization and allowed for the first time the direct detection of antibodies against hepatitis B surface antigen (anti-HBs) in clinical serum samples using surface plasmon resonance (SPR). The fabricated SPR biosensor allowed discrimination of anti-HBs positive and negative clinical samples in 10min. Results are validated by enzyme-linked immunoassays of the sera in a certified laboratory. The sensor could be regenerated by simple treatment with glycine buffer.

Combined Chemical Groups and Topographical Nanopattern on the Poly(ε-Caprolactone) Surface for Regulating Human Foreskin Fibroblasts Behavior

Surface chemistry and substrate topography could contribute significantly to providing a biochemical and topographical cues for governing the fate of cells on the cell-material interface. However, the synergies between these two properties have not been exploited extensively for biomaterial design. Herein, we achieved spatial-controlled patterning of chemical groups on the poly(ε-caprolactone) (PCL) surface by elegant UV-nanoimprint lithography (UN-NIL). The introduction of chemical groups on the PCL surface was developed by our newly 6-benzyloxycarbonylmethyl-ε-caprolactone (BCL) monomer, which not only solved the lack of functional groups along the PCL chain but also retained the original favorable properties of PCL materials. The synergetic effect of the chemical groups and nanopatterns on the human foreskin fibroblasts (HFFs) behaviors was evaluated in detail. The results revealed that the patterned functional PCL surfaces could induce enhanced cell adhesion and proliferation, further trigger changes in HFFs morphology, orientation and collagen secretion. Taken together, this study provided a method for straightforward fabrication of reactive PCL surfaces with topographic patterns by one-step process, and they would facilitate PCL as potential candidate for cell cultivation and tissue engineering.

Biomimetic honeycomb-patterned surface as the tunable cell adhesion scaffold

PS honeycomb structured surfaces were modified into both cell-philic and cell-phobic by dip-coating and casting polySBMA, respectively, which was inspired by two typically adhesive behaviours of fish skin and Parthenocissus tricuspidata.

Blood compatible materials: state of the art

Devices that function in contact with blood are ubiquitous in clinical medicine and biotechnology. These devices include vascular grafts, coronary stents, heart valves, catheters, hemodialysers, heart-lung bypass systems and many others. Blood contact generally leads to thrombosis (among other adverse outcomes), and no material has yet been developed which remains thrombus-free indefinitely and in all situations: extracorporeally, in the venous circulation and in the arterial circulation. In this article knowledge on blood-material interactions and "thromboresistant" materials is reviewed. Current approaches to the development of thromboresistant materials are discussed including surface passivation; incorporation and/or release of anticoagulants, antiplatelet agents and thrombolytic agents; and mimicry of the vascular endothelium.

125I-radiolabeling, surface plasmon resonance, and quartz crystal microbalance with dissipation: three tools to compare protein adsorption on surfaces of different wettability

The extent of protein adsorption is an important consideration in the biocompatibility of biomaterials. Various experimental methods can be used to determine the quantity of protein adsorbed, but the results usually differ. In the present work, self-assembled monolayers (SAMs) were used to prepare a series of model gold surfaces varying systematically in water wettability, from hydrophilic to hydrophobic. Three commonly used methods, namely, surface plasmon resonance (SPR), quartz crystal microbalance with dissipation (QCM-D), and (125)I-radiolabeling, were employed to quantify fibrinogen (Fg) adsorption on these surfaces. This approach allows a direct comparison of the mass of Fg adsorbed using these three techniques. The results from all three methods showed that protein adsorption increases with increasing surface hydrophobicity. The increase in the mass of Fg adsorbed with increasing surface hydrophobicity in the SPR data was parallel to that from (125)I-radiolabeling, but the absolute values were different and there does not seem to be a "universally congruent" relationship between the two methods for surfaces with varying wettability. For QCM-D, the variation in protein adsorption with wettability was different from that for SPR and radiolabeling. On the more hydrophobic surfaces, QCM-D gave an adsorbed mass much higher than from the two other methods, possibly because QCM-D measures both the adsorbed Fg and its associated water. However, on the more hydrophilic surfaces, the adsorbed mass from QCM-D was slightly greater than that from SPR, and both were smaller than from (125)I-radiolabeling; this was true no matter whether the Sauerbrey equation or the Voigt model was used to convert QCM-D data to adsorbed mass.

Exploiting end group functionalization for the design of antifouling bioactive brushes

The Diels–Alder reaction between cyclopentadiene and maleimide is exploited to immobilize proteins on the chain-end of polymer brushes.

Combining surface topography with polymer chemistry: exploring new interfacial biological phenomena

This review focuses on combining surface topography and surface chemical modification by the grafting of polymers to develop optimal material interfaces with synergistic properties and functions for biological and biomedical applications.

The effect of electrically charged polyion complex nanoparticle-coated surfaces on adipose-derived stromal progenitor cell behaviour

Surface characteristics of biomaterials such as wettability, rigidity, roughness, and electrical charge affect the fate of transplanted cells such as progenitor cells or stem cells for use in regenerative medicine. Of these, the effects of surface electrical charges on cellular behaviour such as adhesion, proliferation, and differentiation are not well understood. We prepared precisely charged culture surfaces ranging from -28 mV to +21 mV, simply by surface deposition of polyion complex nanoparticles prepared by mixing a positively charged thermoresponsive homopolymer, poly(N,N-dimethylaminoethyl methacrylate), with negatively charged plasmid DNA at various charge ratios. Drastic morphological changes of adipose-derived vascular progenitor cells were generated on the positively charged surface of organized forms at +19 mV. Capillary-like networks or single aggregates of these cells were selectively created depending on cell seeding density. Our findings offer new insights that may aid develop stem cell-processing techniques for use in regenerative medicine.

Lotus-leaf-like topography predominates over adsorbed ECM proteins in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) surface/cell interactions

It is well-known that extracellular matrix (ECM) proteins mediate cell/surface interactions. However, introduction of a specific surface topography may disturb the correlation between ECM proteins adsorption and cells adhesion on a given surface. In present study, lotus-leaf-like topography was introduced on the surface of a biodegradable material, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx). Protein adsorption and cell interactions with this lotus-leaf-like surface (designated PHBHHx-L) were investigated. Water contact angle data indicated that the hydrophobicity of PHBHHx was enhanced by the introduction of lotus-leaf-like topography. The adsorption of extracellular matrix proteins (fibronectin and vitronectin) on PHBHHx-L was measured by enzyme linked immunosorbent assay (ELISA). Compared with flat PHBHHx, adsorption on the PHBHHx-L surface increased by ~260% for fibronectin and ~40% for vitronectin. In contrast, fibroblast and endothelial cell adhesion and proliferation were reduced on the PHBHHx-L compared to the flat polymer surface. These results suggest that the inhibition of cell adhesion and proliferation caused by the lotus-leaf-like topography dominates over the effect of the adsorbed adhesive proteins in promoting adhesion and proliferation. It can be concluded that the lotus-leaf-like topography plays a dominant role in cell/PHBHHx-L interactions. The present findings indicate the complexity of the interplay among surface topography, adsorbed proteins, and cell-surface interactions.