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.

The response of human osteoblasts on bovine xenografts with and without hyaluronate used in bone augmentation

The aim of the in vitro study was to asses the effect of hyaluronate in conjunction with bovine derived xenografts on the viability, proliferation on day 4, 7 and 10, expression of early osteogenic differentiation marker Alkaline phosphatase on day 14 and 21, collagen, calcium deposition on day 14, 21 and 28 and cellular characteristics, as assessed through live cell image analysis, confocal laser scanning microscopy and scanning electron microscopy, in primary human osteoblasts compared to three bovine xenografts without hyaluronate. All experiments were performed in triplicates. Data were compared between groups and timepoints using one-way analysis of variance (ANOVA). Bonferroni post hoc test were further used for multiple comparison between groups (p < .05) An increase in cell viability (p < .05) and enhanced ALP activity was observed in all xenografts. Specimens containing hyaluronate showed a highest significant difference (23755 ± 29953, p < .0001). The highest levels of calcium (1.60 ± 0.30) and collagen (1.92 ± 0.09, p < .0001) deposition were also observed with hyaluronate loaded groups. The osteoblasts were well attached and spread on all xenograft groups. However, a higher number of cells were observed with hyaluronate functionalized xenograft (76.27 ± 15.11, (p < .0001) in live cell image analysis and they migrated towards the graft boundaries. The biofunctionalization of xenografts with hyaluronate improves their in vitro performance on human osteoblasts. This suggests that hyaluronate might be able to improve the bone regeneration when using such xenografts.

Off-the-Shelf Synthetic Biodegradable Grafts Transform In Situ into a Living Arteriovenous Fistula in a Large Animal Model

Current vascular access options require frequent interventions. In situ tissue engineering (TE) may overcome these limitations by combining the initial success of synthetic grafts with long-term advantages of autologous vessels by using biodegradable grafts that transform into autologous vascular tissue at the site of implantation. Scaffolds (6 mm-Ø) made of supramolecular polycarbonate-bisurea (PC-BU), with a polycaprolactone (PCL) anti-kinking-coil, are implanted between the carotid artery and jugular vein in goats. A subset is bio-functionalized using bisurea-modified-Stromal cell-derived factor-1α (SDF1α) derived peptides and ePTFE grafts as controls. Grafts are explanted after 1 and 3 months, and evaluated for material degradation, tissue formation, compliance, and patency. At 3 months, the scaffold is resorbed and replaced by vascular neo-tissue, including elastin, contractile markers, and endothelial lining. No dilations, ruptures, or aneurysms are observed and grafts are successfully cannulated at termination. SDF-1α-peptide-biofunctionalization does not influence outcomes. Patency is lower in TE grafts (50%) compared to controls (100% patency), predominantly caused by intimal hyperplasia. Rapid remodeling of a synthetic, biodegradable vascular scaffold into a living, compliant arteriovenous fistula is demonstrated in a large animal model. Despite lower patency compared to ePTFE, transformation into autologous and compliant living tissue with self-healing capacity may have long-term advantages.

Two-Layer Inkjet-Printed Microwave Split-Ring Resonators for Detecting Analyte Binding to the Gold Surface

This work focuses on demonstrating the working principle of inkjet-printed Au nanoparticle (NP) two-layer Gigahertz (2.6 GHz) microwave split-ring resonators (SRRs) as a novel platform for the detection of analytes on flexible substrates. In contrast to the standard fabrication of split-ring resonator biosensors using printed circuit board technology, which results in a seven-layer system, the resonators in this work were fabricated using a two-layer system. A ground plane is embedded in the SRR measurement setup. In this method, a microwave electromagnetic wave is coupled into the Au SRR via an inkjet-printed Cu-NP stripline that is photonically sintered. This coupling mechanism facilitates the detection of analytes by inducing resonance shifts in the SRR. In this study, the functionality of the printed sensors was demonstrated using two different Au functionalization processes, firstly, with HS-PEG7500-COOH, and, secondly, with protein G with an N-terminal cysteine residue. The sensing capabilities of the printed structures are shown by the attachment of biomolecules to the SRR and the measurement of the resulting resonance shift. The experiments show a clear shift of the resonance frequency in the range of 20-30 MHz for both approaches. These results demonstrate the functionality of the simplified printed two-layer microwave split-ring resonator for use as a biosensor.

Supramolecular Heterodimer Peptides Assembly for Nanoparticles Functionalization

Nanoparticle (NP) surface functionalization with proteins, including monoclonal antibodies (mAbs), mAb fragments, and various peptides, has emerged as a promising strategy to enhance tumor targeting specificity and immune cell interaction. However, these methods often rely on complex chemistry and suffer from batch-dependent outcomes, primarily due to limited control over the protein orientation and quantity on NP surfaces. To address these challenges, a novel approach based on the supramolecular assembly of two peptides is presented to create a heterotetramer displaying VH Hs on NP surfaces. This approach effectively targets both tumor-associated antigens (TAAs) and immune cell-associated antigens. In vitro experiments showcase its versatility, as various NP types are biofunctionalized, including liposomes, PLGA NPs, and ultrasmall silica-based NPs, and the VH Hs targeting of known TAAs (HER2 for breast cancer, CD38 for multiple myeloma), and an immune cell antigen (NKG2D for natural killer (NK) cells) is evaluated. In in vivo studies using a HER2+ breast cancer mouse model, the approach demonstrates enhanced tumor uptake, retention, and penetration compared to the behavior of nontargeted analogs, affirming its potential for diverse applications.

The Effect of Multilayered Electrospun PLLA Nanofibers Coated with Human Amnion or Bladder ECM Proteins on Epithelialization and Smooth Muscle Regeneration in the Rabbit Bladder

Nanofibrous scaffolds have attracted much attention in bladder reconstruction approaches due to their excellent mechanical properties. In addition, their biological properties can be improved by combination with biological materials. Taking into account the advantages of nanofibrous scaffolds and decellularized extracellular matrix (dECM) in tissue engineering, scaffolds of poly-L-lactic acid (PLLA) coated with decellularized human amnion membrane (hAM) or sheep bladder (SB)-derived ECM proteins are developed (amECM-coated PLLA and sbECM-coated PLLA, respectively). The bladder regenerative potential of modified electrospun PLLA scaffolds is investigated in rabbits. The presence of ECM proteins is confirmed on the nanofibers' surface. Coating the surface of the PLLA nanofibers improves cell adhesion and proliferation. Histological and immunohistochemical evaluations show that rabbits subjected to cystoplasty with a multilayered PLLA scaffold show de novo formation and maturation of the multilayered urothelial layer. However, smooth muscle bundles (myosin heavy chain [MHC] and α-smooth muscle actin [α-SMA] positive) are detected only in ECM-coated PLLA groups. All groups show no evidence of a diverticulumor fistula in the urinary bladder. These results suggest that the biofunctionalization of electrospun PLLA nanofibers with ECM proteins can be a promising option for bladder tissue engineering. Furthermore, hAM can also replace animal-sourced ECM proteins in bladder tissue regeneration approaches.

(Bio)Functionalisation of Metal-Organic Polyhedra by Using Click Chemistry

The surface chemistry of Metal-Organic Polyhedra (MOPs) is crucial to their physicochemical properties because it governs how they interact with external substances such as solvents, synthetic organic molecules, metal ions, and even biomolecules. Consequently, the advancement of synthetic methods that facilitate the incorporation of diverse functional groups onto MOP surfaces will significantly broaden the range of properties and potential applications for MOPs. This study describes the use of copper(I)-catalysed, azide-alkyne cycloaddition (CuAAC) click reactions to post-synthetically modify the surface of alkyne-functionalised cuboctahedral MOPs. To this end, a novel Rh(II)-based MOP with 24 available surface alkyne groups was synthesised. Each of the 24 alkyne groups on the surface of the "clickable" Rh-MOP can react with azide-containing molecules at room temperature, without compromising the integrity of the MOP. The wide substrate catalogue and orthogonal nature of CuAAC click chemistry was exploited to densely functionalise MOPs with diverse functional groups, including polymers, carboxylic and phosphonic acids, and even biotin moieties, which retained their recognition capabilities once anchored onto the surface of the MOP.

Biosynthesis of Zinc Oxide Nanoparticles on l-Carnosine Biofunctionalized Polyacrylonitrile Nanofibers; a Biomimetic Wound Healing Material

Multifunctional biohybrid nanofibers (NFs) that can simultaneously drive various cellular activities and confer antibacterial properties are considered desirable in producing advanced wound healing materials. In this study, a bionanohybrid formulation was processed as a NF wound dressing to stimulate the adhesion and proliferation of fibroblast and endothelial cells that play a major role in wound healing. Polyacrylonitrile (PAN) electrospun NFs were hydrolyzed using NaOH and biofunctionalized with l-carnosine (CAR), a dipeptide which could later biosynthesize zinc oxide (ZnO) nanoparticles (NPs) on the NFs surface. The morphological study verified that ZnO NPs are uniformly distributed on the surface of CAR/PAN NFs. Through EDX and XRD analysis, it was validated that the NPs are composed of ZnO and/or ZnO/Zn(OH)2. The presence of CAR and ZnO NPs brought about a superhydrophilicity effect and notably raised the elastic modulus and tensile strength of Zn-CAR/PAN NFs. While CAR ligands were shown to improve the viability of fibroblast (L929) and endothelial (HUVEC) cells, ZnO NPs lowered the positive impact of CAR, most likely due to their repulsive negative surface charge. A scratch assay verified that CAR/PAN NFs and Zn-CAR/PAN NFs aided HUVEC migration more than PAN NFs. Also, an antibacterial assay implied that CAR/PAN NFs and Zn-CAR/PAN NFs are significantly more effective in inhibiting Staphylococcus aureus (S. aureus) than neat PAN NFs are (1000 and 500%, respectively). Taken together, compared to the neat PAN NFs, CAR/PAN NFs with and without the biosynthesized ZnO NPs can support the cellular activities of relevance for wound healing and inactivate bacteria.

Noninvasive In Vivo Imaging of T-Cells during Cancer Immunotherapy Using Rare-Earth Nanoparticles

Only a minority of patients respond positively to cancer immunotherapy, and addressing this variability is an active area of immunotherapy research. Infiltration of tumors by immune cells is one of the most significant prognostic indicators of response and disease-free survival. However, the ability to noninvasively sample the tumor microenvironment for immune cells remains limited. Imaging in the near-infrared-II region using rare-earth nanocrystals is emerging as a powerful imaging tool for high-resolution deep-tissue imaging. In this paper, we demonstrate that these nanoparticles can be used for noninvasive in vivo imaging of tumor-infiltrating T-cells in a highly aggressive melanoma tumor model. We present nanoparticle synthesis and surface modification strategies for the generation of small, ultrabright, and biocompatible rare-earth nanocrystals necessary for deep tissue imaging of rare cell types. The ability to noninvasively monitor the immune contexture of a tumor during immunotherapy could lead to early identification of nonresponding patients in real time, leading to earlier interventions and better outcomes.

Scanning Tunneling Microscopy Study of Lipoic Acid, Mannose, and cRGD@AuNPs Conjugates

The functionalization of AuNPs with different biological elements was achieved to investigate their possibility in biomedical applications such as drug delivery, vaccine development, sensing, and imaging. Biofunctionalized AuNPs are pursued for applications such as drug delivery, vaccine development, sensing, and imaging. In this study, AuNPs with diameters of 20 nm were functionalized with lipoic acid, mannose, or the cRGD peptide. By using UV-vis spectroscopy, Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, and scanning tunneling microscopy techniques, we showed that AuNPs can be functionalized by these biomolecules in a reliable way to obtain conjugates to explore potential biomedical applications. In particular, we demonstrate that the STM technique can be employed to analyze biofunctionalized AuNPs, and the obtained information can be valuable in the design of biomedical applications.

Antibacterial and Antifungal Properties of Polyester, Polylactide, and Cotton Nonwovens and Fabrics, by Means of Stable Aqueous Dispersions Containing Copper Silicate and Some Metal Oxides

Literature reviews have described the applications of silver, copper, and zinc ions and metallic particles of Cu, Ti, and Zn oxides, which have been found to be useful antimicrobial reagents for the biofunctionalization of various materials and their surfaces. For this purpose, compositions of water dispersions containing emulsions of synthetic copolymers based on acrylic and vinyl monomers, polysaccharides (hydroxyethyl cellulose and starch), and various additives with wetting and stabilizing properties were used. Many stable water dispersions of different chemical compositions containing bioactive chemical compounds (copper silicate hydrate, titanium dioxide, and zinc oxide (and other auxiliary substances)) were developed. They were used for the preparation of thin hybrid coatings having good antimicrobial properties against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus), and yeast fungus (Candida albicans). Polyester (PES) and polylactide (PLA) nonwovens were modified using the dip-coating method, while PES and cotton fabrics were biofunctionalized by means of dip-coating and coating methods. The antimicrobial (antibacterial and antifungal) properties of the textile materials (nonwovens and fabrics) biofunctionalized with the above-mentioned bioactive agents exhibiting antimicrobial properties (CuSiO3, TiO2, ZnO, or ZnO∙SiO2) were strongly dependent on the agents' content in the water dispersions. The PES and PLA nonwovens, modified on the surface with water compositions containing copper silicate hydrate, showed good antibacterial properties against the Gram-negative bacteria Escherichia coli, even at a content of 1 wt.% CuSiO3∙xH2O, and against the Gram-positive bacteria Staphylococcus aureus, at the content of at least 5 wt.% CuSiO3∙xH2O. The bacterial growth reduction factor (R) was greater than 99% for most of the samples tested. Good antifungal properties against the fungus Candida albicans were found for the PES and PLA nonwoven fabrics modified with dispersions containing 5-7 wt.% CuSiO3∙xH2O and 4.2-5.0 wt.% TiO2. The addition of TiO2 led to a significant improvement in the antifungal properties of the PES and PLA nonwovens modified in this way. For the samples of PES WIFP-270 and FS F-5 nonwovens, modified with water dispersions containing 5.0 wt.% CuSiO3∙xH2O and 4.2-5.0 wt.% TiO2, the growth reduction factor for the fungus Candida albicans (R) reached values in the range of 80.9-98.0%. These new biofunctionalized polymeric nonwoven textile materials can find practical applications in the manufacture of filters for hospital air-conditioning systems and for the automotive industry, as well as in air purification devices. Moreover, similar antimicrobial modification of fabrics with the dip-coating or coating methods can be applied, for example, in the fabrication of fungi- and mold-resistant garden furniture.

Peptide-Functionalized Electrospun Meshes for the Physiological Cultivation of Pulmonary Alveolar Capillary Barrier Models in a 3D-Printed Micro-Bioreactor

In vitro environments that realize biomimetic scaffolds, cellular composition, physiological shear, and strain are integral to developing tissue models of organ-specific functions. In this study, an in vitro pulmonary alveolar capillary barrier model is developed that closely mimics physiological functions by combining a synthetic biofunctionalized nanofibrous membrane system with a novel three-dimensional (3D)-printed bioreactor. The fiber meshes are fabricated from a mixture of polycaprolactone (PCL), 6-armed star-shaped isocyanate-terminated poly(ethylene glycol) (sPEG-NCO), and Arg-Gly-Asp (RGD) peptides by a one-step electrospinning process that offers full control over the fiber surface chemistry. The tunable meshes are mounted within the bioreactor where they support the co-cultivation of pulmonary epithelial (NCI-H441) and endothelial (HPMEC) cell monolayers at air-liquid interface under controlled stimulation by fluid shear stress and cyclic distention. This stimulation, which closely mimics blood circulation and breathing motion, is observed to impact alveolar endothelial cytoskeleton arrangement and improve epithelial tight junction formation as well as surfactant protein B production compared to static models. The results highlight the potential of PCL-sPEG-NCO:RGD nanofibrous scaffolds in combination with a 3D-printed bioreactor system as a platform to reconstruct and enhance in vitro models to bear a close resemblance to in vivo tissues.

Microalgae Applications to Bone Repairing Processes: A Review

Research on regeneration and accelerated recovery processes of bone tissue has driven a growing interest in the scientific community. Implementing natural materials to reduce rejections due to biocompatibility issues is an important trend. Biofunctionalization processes have been proposed to promote osseointegration in implant materials, and those substances able to generate an adequate environment for cell proliferation are the object of several studies. Because of their high protein content and their anti-inflammatory, antibacterial, antimicrobial, and healing properties, microalgae represent a natural source of bioactive compounds, and are proposed as candidates for tissue regeneration applications. In this paper microalgae are reviewed as a source of biofunctionalized materials focused on orthopedic applications.

Recombinant perlecan domain V covalently immobilized on silk biomaterials via plasma immersion ion implantation supports the formation of functional endothelium

Strategies to promote rapid formation of functional endothelium are required to maintain blood fluidity and regulate smooth muscle cell proliferation in synthetic vascular conduits. In this work, we explored the biofunctionalization of silk biomaterials with recombinantly expressed domain V of human perlecan (rDV) to promote endothelial cell interactions and the formation of functional endothelium. Perlecan is essential in vascular development and homeostasis and rDV has been shown to uniquely support endothelial cell, while inhibiting smooth muscle cell and platelet interactions, both key contributors of vascular graft failure. rDV was covalently immobilized on silk using plasma immersion ion implantation (PIII), a simple one-step surface treatment process which enables strong immobilization in the absence of chemical cross-linkers. rDV immobilization on surface-modified silk was assessed for amount, orientation, and bio-functionality in terms of endothelial cell interactions and functional endothelial layer formation. rDV immobilized on PIII-treated silk (rDV-PIII-silk) supported rapid endothelial cell adhesion, spreading, and proliferation to form functional endothelium, as evidenced by the expression of vinculin and VE-cadherin markers. Taken together, the results provide evidence for the potential of rDV-PIII-silk as a biomimetic vascular graft material.

Aqueous Two-Phase Enabled Low Viscosity 3D (LoV3D) Bioprinting of Living Matter

Embedded 3D bioprinting has great value for the freeform fabrication of living matter. However, embedded 3D bioprinting is currently limited to highly viscous liquid baths or liquid-like solid baths. In contrast, prior to crosslinking, most hydrogels are formulated as low-viscosity solutions and are therefore not directly compatible with bioprinting due to low shape fidelity and poor print stability. The authors here present a method to enable low-viscosity ink 3D (LoV3D) bioprinting, based on aqueous two-phase stabilization of the ink-bath interface. LoV3D allows for the printing of living constructs at high extrusion speeds (up to 1.8 m s^-1 ) with high viability due to its exceedingly low-viscosity. Moreover, LoV3D liquid/liquid interfaces offer unique advantages for fusing printed structures, creating intricate vasculature, and modifying surfaces at higher efficiencies than traditional systems. Furthermore, the low interfacial tension of LoV3D bioprinting offers unprecedented nozzle-independent control over filament diameter via large-dimension strand-thinning, which allows for the printing of an exceptionally wide range of diameters down to the width of a single cell. Overall, LoV3D bioprinting is a unique all-aqueous approach with broad material compatibility without the need for rheological ink adaption, which opens new avenues of application in cell patterning, drug screening, engineered meat, and organ fabrication.

Automated Folding of Origami Lattices: From Nanopatterned Sheets to Stiff Meta-Biomaterials

Folding nanopatterned flat sheets into complex 3D structures enables the fabrication of meta-biomaterials that combine a rationally designed 3D architecture with nanoscale surface features. Self-folding is an attractive approach for realizing such materials. However, self-folded lattices are generally too compliant as there is an inherent competition between ease-of-folding requirements and final load-bearing characteristics. Inspired by sheet metal forming, an alternative route is proposed for the fabrication of origamilattices. This 'automated-folding' approach allows for the introduction of sharp folds into thick metal sheets, thereby enhancing their stiffness. The first time realization of automatically folded origami lattices with bone-mimicking mechanical properties is demonstrated. The proposed approach is highly scalable given that the unit cells making up the meta-biomaterial can be arbitrarily large in number and small in dimensions. To demonstrate the scalability and versatility of the proposed approach, it is fabricated origamilattices with > 100 unit cells, lattices with unit cells as small as 1.25 mm, and auxetic lattices. The nanopatterned the surface of the sheets prior to folding. Protected by a thin coating layer, these nanoscale features remained intact during the folding process. It is found that the nanopatterned folded specimens exhibits significantly increased mineralization as compared to their non-patterned counterparts.

Biofunctionalization of Multiplexed Silicon Photonic Biosensors

Silicon photonic (SiP) sensors offer a promising platform for robust and low-cost decentralized diagnostics due to their high scalability, low limit of detection, and ability to integrate multiple sensors for multiplexed analyte detection. Their CMOS-compatible fabrication enables chip-scale miniaturization, high scalability, and low-cost mass production. Sensitive, specific detection with silicon photonic sensors is afforded through biofunctionalization of the sensor surface; consequently, this functionalization chemistry is inextricably linked to sensor performance. In this review, we first highlight the biofunctionalization needs for SiP biosensors, including sensitivity, specificity, cost, shelf-stability, and replicability and establish a set of performance criteria. We then benchmark biofunctionalization strategies for SiP biosensors against these criteria, organizing the review around three key aspects: bioreceptor selection, immobilization strategies, and patterning techniques. First, we evaluate bioreceptors, including antibodies, aptamers, nucleic acid probes, molecularly imprinted polymers, peptides, glycans, and lectins. We then compare adsorption, bioaffinity, and covalent chemistries for immobilizing bioreceptors on SiP surfaces. Finally, we compare biopatterning techniques for spatially controlling and multiplexing the biofunctionalization of SiP sensors, including microcontact printing, pin- and pipette-based spotting, microfluidic patterning in channels, inkjet printing, and microfluidic probes.

A Study of the Interface of Gold Nanoparticles Conjugated to Cowpea Fe-Superoxide Dismutase

The iron superoxide dismutase (FeSOD) is a first barrier to defend photosynthetic organisms from superoxide radicals. Although it is broadly present in plants and bacteria, FeSODs are absent in animals. They belong to the same phylogenic family as Mn-containing SODs, which are also highly efficient at detoxifying superoxide radicals. In addition, SODs can react with peroxynitrite, and FeSOD enzyme has already been used to evaluate the anti-nitrative capacity of plant antioxidants. Gold nanoparticles (AuNPs) have been shown to significantly improve the functionality and the efficiency of ligands, providing they are properly assembled. In this work, the characteristics of the recombinant cowpea (Vigna unguiculata) FeSOD (rVuFeSOD) immobilized onto AuNPs were investigated as a function of (1) NP surface chemistry and (2) biofunctionalization methods, either physical adsorption or covalent bonding. The NP surface chemistry was studied by varying the concentration of the ligand molecule 11-mercaptoundecanoic acid (MUA) on the NP surface. The coverage and activity of the protein on AuNPs was determined and correlated to the surface chemistry and the two biofunctionalization methods. rVuFeSOD-AuNPs conjugate stability was monitored through absorption measurements, agarose gel electrophoresis and DLS, enzymatic activity by a colorimetric assay and by in-gel activity assay, and coverage was measured by colorimetric assay. When using physical adsorption, the NP is the most perturbing agent for the activity of the enzyme. In contrast, only the NP coverage was affected by MUA ligand concentration. However, during covalent attachment, both the NP and the concentration of MUA on the surface influenced the enzyme activity, while the coverage of the NP remained constant. The results evidence the importance of the biomolecule and AuNP interaction for the functionality of the hybrid. These strategies can be used to develop electrochemical biosensors for O2•- and for peroxynitrite in biomedical applications.

Surface Biofunctionalization of Silk Biomaterials Using Dityrosine Cross-Linking

Biofunctionalization of silk biomaterial surfaces with extracellular matrix (ECM) molecules, cell binding peptides, or growth factors is important in a range of applications, including tissue engineering and development of implantable medical devices. Passive adsorption is the most common way to immobilize molecules of interest on preformed silk biomaterials but can lead to random molecular orientations and displacement from the surface, limiting their applications. Herein, we developed techniques for covalent immobilization of biomolecules using enzyme- or photoinitiated formation of dityrosine bonds between the molecule of interest and silk. Using recombinantly expressed domain V of the human basement membrane proteoglycan perlecan (rDV) as a model molecule, we demonstrated that rDV can be covalently immobilized via dityrosine cross-linking without the need to modify rDV or silk biomaterials. Dityrosine-based immobilization resulted in a different molecular orientation to passively absorbed rDV with less C- and N-terminal region exposure on the surface. Dityrosine-based immobilization supported functional rDV immobilization where immobilized rDV supported endothelial cell adhesion, spreading, migration, and proliferation. These results demonstrate the utility of dityrosine-based cross-linking in covalent immobilization of tyrosine-containing molecules on silk biomaterials in the absence of chemical modification, adding a simple and accessible technique to the silk biofunctionalization toolbox.

Collagen-Based Osteogenic Nanocoating of Microrough Titanium Surfaces

The aim of the present study was to develop a collagen/heparin-based multilayer coating on titanium surfaces for retarded release of recombinant human bone morphogenic protein 2 (rhBMP2) to enhance the osteogenic activity of implant surfaces. Polyelectrolyte multilayer (PEM) coatings were constructed on sandblasted/acid-etched surfaces of titanium discs using heparin and collagen. PEM films of ten double layers were produced and overlayed with 200 µL of a rhBMP2 solution containing 15 µg rhBMP2. Subsequently, cross-linking of heparin molecules was performed using EDC/NHS chemistry to immobilize the incorporated rhBMP2. Release characteristics for 3 weeks, induction of Alkaline Phosphatase (ALP) in C2C12 cells and proliferation of human mesenchymal stem cells (hMSCs) were evaluated to analyze the osteogenic capacity of the surface. The coating incorporated 10.5 µg rhBMP2 on average per disc and did not change the surface morphology. The release profile showed a delivery of 14.5% of the incorporated growth factor during the first 24 h with a decline towards the end of the observation period with a total release of 31.3%. Cross-linking reduced the release with an almost complete suppression at 100% cross-linking. Alkaline Phosphatase was significantly increased on day 1 and day 21, indicating that the growth factor bound in the coating remains active and available after 3 weeks. Proliferation of hMSCs was significantly enhanced by the non-cross-linked PEM coating. Nanocoating using collagen/heparin-based PEMs can incorporate clinically relevant amounts of rhBMP2 on titanium surfaces with a retarded release and a sustained enhancement of osteogenic activity without changing the surface morphology.

Functional Ultra-High Molecular Weight Polyethylene Composites for Ligament Reconstructions and Their Targeted Applications in the Restoration of the Anterior Cruciate Ligament

The selection of biomaterials as biomedical implants is a significant challenge. Ultra-high molecular weight polyethylene (UHMWPE) and composites of such kind have been extensively used in medical implants, notably in the bearings of the hip, knee, and other joint prostheses, owing to its biocompatibility and high wear resistance. For the Anterior Cruciate Ligament (ACL) graft, synthetic UHMWPE is an ideal candidate due to its biocompatibility and extremely high tensile strength. However, significant problems are observed in UHMWPE based implants, such as wear debris and oxidative degradation. To resolve the issue of wear and to enhance the life of UHMWPE as an implant, in recent years, this field has witnessed numerous innovative methodologies such as biofunctionalization or high temperature melting of UHMWPE to enhance its toughness and strength. The surface functionalization/modification/treatment of UHMWPE is very challenging as it requires optimizing many variables, such as surface tension and wettability, active functional groups on the surface, irradiation, and protein immobilization to successfully improve the mechanical properties of UHMWPE and reduce or eliminate the wear or osteolysis of the UHMWPE implant. Despite these difficulties, several surface roughening, functionalization, and irradiation processing technologies have been developed and applied in the recent past. The basic research and direct industrial applications of such material improvement technology are very significant, as evidenced by the significant number of published papers and patents. However, the available literature on research methodology and techniques related to material property enhancement and protection from wear of UHMWPE is disseminated, and there is a lack of a comprehensive source for the research community to access information on the subject matter. Here we provide an overview of recent developments and core challenges in the surface modification/functionalization/irradiation of UHMWPE and apply these findings to the case study of UHMWPE for ACL repair.

Hyaluronic Acid with Bone Substitutes Enhance Angiogenesis In Vivo

Introduction: The effective induction of angiogenesis is directly related to the success of bone-substitute materials (BSM) for maxillofacial osseous regeneration. Therefore, the addition of pro-angiogenic properties to a commercially available bovine bone-substitute material in combination with hyaluronic acid (BSM+) was compared to the same bone-substitute material without hyaluronic acid (BSM) in an in-vivo model. Materials and Methods: BSM+ and BSM were incubated for six days on the chorioallantoic membrane (CAM) of fertilized chicken eggs. Microscopically, the number of vessels and branching points, the vessel area and vessel length were evaluated. Subsequently, the total vessel area and brightness integration were assessed after immunohistochemical staining (H&E, alphaSMA). Results: In the BSM+ group, a significantly higher number of vessels (p < 0.001), branching points (p = 0.001), total vessel area (p < 0.001) as well as vessel length (p = 0.001) were found in comparison to the BSM group without hyaluronic acid. Immunohistochemically, a significantly increased total vessel area (p < 0.001 for H&E, p = 0.037 for alphaSMA) and brightness integration (p = 0.047) for BSM+ in comparison to the native material were seen. Conclusions: The combination of a xenogenic bone-substitute material with hyaluronic acid significantly induced angiogenesis in vivo. This might lead to a faster integration and an improved healing in clinical situations.

Development of a system of heparin multilayers on titanium surfaces for dual growth factor release

The aim of the present study was to establish a modular platform of poly-L-lysine-heparin (PLL-Hep) polyelectrolyte multilayer (PEM) coatings on titanium surfaces for dual growth factor delivery of recombinant human bone morphogenic protein 2 (rhBMP2) and recombinant human vascular endothelial growth factor 165 (rhVEGF165) in clinically relevant quantities. Release characteristics for both growth factors differed significantly depending on film architecture. rhBMP2 induced activation of alkaline phosphatase in C2C12 cells and proliferation of human mesenchymal stem cells (hMSCs). rhVEGF mediated induction of von Willebrand factor (vWF) in hMSCs and proliferation of human umbilical vein endothelial cells. Osteogenic and angiogenic effects were modified by variation in cross-linking and architecture of the PEMs. By creating multilayer films with distinct zones, release characteristics and proportion of both growth factor delivery could be tuned and surface-activity modified to enhance angiogenic or osteogenic function in various ways. In summary, the system provides a modular platform for growth factor delivery that allows for individual composition and accentuation of angiogenic and osteogenic surface properties.

Functionalization of Water-Soluble Conjugated Polymers for Bioapplications

Water-soluble conjugated polymers (WS-CPs) have found widespread use in bioapplications ranging from in vitro optical sensing to in vivo phototherapy. Modification of WS-CPs with specific molecular functional units is necessary to enable them to interact with biological targets. These targets include proteins, nucleic acids, antibodies, cells, and intracellular components. WS-CPs have been modified with covalently linked sugars, peptides, nucleic acids, biotin, proteins, and other biorecognition elements. The objective of this article is to comprehensively review the various synthetic chemistries that have been used to covalently link biofunctional groups onto WS-CP platforms. These chemistries include amidation, nucleophilic substitution, Click reactions, and conjugate addition. Different types of WS-CP backbones have been used as platforms including poly(fluorene), poly(phenylene ethynylene), polythiophene, poly(phenylenevinylene), and others. Example applications of biofunctionalized WS-CPs are also reviewed. These include examples of protein sensing, flow cytometry labeling, and cancer therapy. The major challenges and future development of functionalized conjugated polymers are also discussed.

Effectiveness of Direct Laser Interference Patterning and Peptide Immobilization on Endothelial Cell Migration for Cardio-Vascular Applications: An In Vitro Study

Endothelial coverage of an exposed cardiovascular stent surface leads to the occurrence of restenosis and late-stent thrombosis several months after implantation. To overcome this difficulty, modification of stent surfaces with topographical or biochemical features may be performed to increase endothelial cells’ (ECs) adhesion and/or migration. This work combines both strategies on cobalt-chromium (CoCr) alloy and studies the potential synergistic effect of linear patterned surfaces that are obtained by direct laser interference patterning (DLIP), coupled with the use of Arg-Gly-Asp (RGD) and Tyr-Ile-Gly-Ser-Arg (YIGSR) peptides. An extensive characterization of the modified surfaces was performed by using AFM, XPS, surface charge, electrochemical analysis and fluorescent methods. The biological response was studied in terms of EC adhesion, migration and proliferation assays. CoCr surfaces were successfully patterned with a periodicity of 10 µm and two different depths, D (≈79 and 762 nm). RGD and YIGSR were immobilized on the surfaces by CPTES silanization. Early EC adhesion was increased on the peptide-functionalized surfaces, especially for YIGSR compared to RGD. High-depth patterns generated 80% of ECs’ alignment within the topographical lines and enhanced EC migration. It is noteworthy that the combined use of the two strategies synergistically accelerated the ECs’ migration and proliferation, proving the potential of this strategy to enhance stent endothelialization.

Integration of Biofunctional Molecules into 3D-Printed Polymeric Micro-/Nanostructures

Three-dimensional printing at the micro-/nanoscale represents a new challenge in research and development to achieve direct printing down to nanometre-sized objects. Here, FluidFM, a combination of microfluidics with atomic force microscopy, offers attractive options to fabricate hierarchical polymer structures at different scales. However, little is known about the effect of the substrate on the printed structures and the integration of (bio)functional groups into the polymer inks. In this study, we printed micro-/nanostructures on surfaces with different wetting properties, and integrated molecules with different functional groups (rhodamine as a fluorescent label and biotin as a binding tag for proteins) into the base polymer ink. The substrate wetting properties strongly affected the printing results, in that the lateral feature sizes increased with increasing substrate hydrophilicity. Overall, ink modification only caused minor changes in the stiffness of the printed structures. This shows the generality of the approach, as significant changes in the mechanical properties on chemical functionalization could be confounders in bioapplications. The retained functionality of the obtained structures after UV curing was demonstrated by selective binding of streptavidin to the printed structures. The ability to incorporate binding tags to achieve specific interactions between relevant proteins and the fabricated micro-/nanostructures, without compromising the mechanical properties, paves a way for numerous bio and sensing applications. Additional flexibility is obtained by tuning the substrate properties for feature size control, and the option to obtain functionalized printed structures without post-processing procedures will contribute to the development of 3D printing for biological applications, using FluidFM and similar dispensing techniques.

Biological Synthesis of Bioactive Gold Nanoparticles from Inonotus obliquus for Dual Chemo-Photothermal Effects against Human Brain Cancer Cells

The possibility for an ecologically friendly and simple production of gold nanoparticles (AuNPs) with Chaga mushroom (Inonotus obliquus) (Ch-AuNPs) is presented in this study. Chaga extract’s reducing potential was evaluated at varied concentrations and temperatures. The nanoparticles synthesized were all under 20 nm in size, as measured by TEM, which is a commendable result for a spontaneous synthesis method utilizing a biological source. The Ch-AuNPs showed anti-cancer chemotherapeutic effects on human brain cancer cells which is attributed to the biofunctionalization of the AuNPs with Chaga bioactive components during the synthesis process. Further, the photothermal ablation capability of the as-prepared gold nanoparticles on human brain cancer cells was investigated. It was found that the NIR-laser induced thermal ablation of cancer cells was effective in eliminating over 80% of the cells. This research projects the Ch-AuNPs as promising, dual modal (chemo-photothermal) therapeutic candidates for anti-cancer applications.

Immobilization of β-Galactosidase by Encapsulation of Enzyme-Conjugated Polymer Nanoparticles Inside Hydrogel Microparticles

Increasing the shelf life of enzymes and making them reusable is a prominent topic in biotechnology. The encapsulation inside hydrogel microparticles (HMPs) can enhance the enzyme's stability by preserving its native conformation and facilitating continuous biocatalytic processes and enzyme recovery. In this study, we present a method to immobilize β-galactosidase by, first, conjugating the enzyme onto the surface of polymer nanoparticles, and then encapsulating these enzyme-conjugated nanoparticles (ENPs) inside HMPs using microfluidic device paired with UV-LEDs. Polymer nanoparticles act as anchors for enzyme molecules, potentially preventing their leaching through the hydrogel network especially during swelling. The affinity binding (through streptavidin-biotin interaction) was used as an immobilization technique of β-galactosidase on the surface of polymer nanoparticles. The hydrogel microparticles of roughly 400 μm in size (swollen state) containing unbound enzyme and ENPs were produced. The effects of encapsulation and storage in different conditions were evaluated. It was discovered that the encapsulation in acrylamide (AcAm) microparticles caused an almost complete loss of enzymatic activity. Encapsulation in poly(ethylene glycol) (PEG)-diacrylate microparticles, on the other hand, showed a residual activity of 15-25%, presumably due to a protective effect of PEG during polymerization. One of the major factors that affected the enzyme activity was presence of photoinitiator exposed to UV-irradiation. Storage studies were carried out at room temperature, in the fridge and in the freezer throughout 1, 7 and 28 days. The polymer nanoparticles showcased excellent immobilization properties and preserved the activity of the conjugated enzyme at room temperature (115% residual activity after 28 days), while a slight decrease was observed for the unbound enzyme (94% after 28 days). Similar trends were observed for encapsulated ENPs and unbound enzyme. Nevertheless, storage at -26°C resulted in an almost complete loss of enzymatic activity for all samples.

Biostack: Nontoxic Metabolite Detection from Live Tissue

There is increasing demand for direct in situ metabolite monitoring from cell cultures and in vivo using implantable devices. Electrochemical biosensors are commonly preferred due to their low-cost, high sensitivity, and low complexity. Metabolite detection, however, in cultured cells or sensitive tissue is rarely shown. Commonly, glucose sensing occurs indirectly by measuring the concentration of hydrogen peroxide, which is a by-product of the conversion of glucose by glucose oxidase. However, continuous production of hydrogen peroxide in cell media with high glucose is toxic to adjacent cells or tissue. This challenge is overcome through a novel, stacked enzyme configuration. A primary enzyme is used to provide analyte sensitivity, along with a secondary enzyme which converts H₂ O₂ back to O₂ . The secondary enzyme is functionalized as the outermost layer of the device. Thus, production of H₂ O₂ remains local to the sensor and its concentration in the extracellular environment does not increase. This "biostack" is integrated with organic electrochemical transistors to demonstrate sensors that monitor glucose concentration in cell cultures in situ. The "biostack" renders the sensors nontoxic for cells and provides highly sensitive and stable detection of metabolites.

Stimulation of Neurite Outgrowth Using Autologous NGF Bound at the Surface of a Fibrous Substrate

Peripheral nerve injury still remains a major clinical challenge, since the available solutions lead to dysfunctional nerve regeneration. Even though autologous nerve grafts are the gold standard, tissue engineered nerve guidance grafts are valid alternatives. Nerve growth factor (NGF) is the most potent neurotrophic factor. The development of a nerve guidance graft able to locally potentiate the interaction between injured neurons and autologous NGF would be a safer and more effective alternative to grafts that just release NGF. Herein, a biofunctional electrospun fibrous mesh (eFM) was developed through the selective retrieval of NGF from rat blood plasma. The neurite outgrowth induced by the eFM-NGF systems was assessed by culturing rat pheochromocytoma (PC12) cells for 7 days, without medium supplementation. The biological results showed that this NGF delivery system stimulates neuronal differentiation, enhancing the neurite growth more than the control condition.

Strategies for Antimicrobial Peptides Immobilization on Surfaces to Prevent Biofilm Growth on Biomedical Devices

Nosocomial and medical device-induced biofilm infections affect millions of lives and urgently require innovative preventive approaches. These pathologies have led to the development of numerous antimicrobial strategies, an emergent topic involving both natural and synthetic routes, among which some are currently under testing for clinical approval and use. Antimicrobial peptides (AMPs) are ideal candidates for this fight. Therefore, the strategies involving surface functionalization with AMPs to prevent bacterial attachment/biofilms formation have experienced a tremendous development over the last decade. In this review, we describe the different mechanisms of action by which AMPs prevent bacterial adhesion and/or biofilm formation to better address their potential as anti-infective agents. We additionally analyze AMP immobilization techniques on a variety of materials, with a focus on biomedical applications. Furthermore, we summarize the advances made to date regarding the immobilization strategies of AMPs on various surfaces and their ability to prevent the adhesion of various microorganisms. Progress toward the clinical approval of AMPs in antibiotherapy is also reviewed.

Efficient Chemical Surface Modification Protocol on SiO2 Transducers Applied to MMP9 Biosensing

The bioreceptor immobilization process (biofunctionalization) turns to be one of the bottlenecks when developing a competent and high sensitivity label-free biosensor. Classical approaches seem to be effective but not efficient. Although biosensing capacities are shown in many cases, the performance of the biosensor is truncated by the inefficacious biofunctionalization protocol and the lack of reproducibility. In this work, we describe a unique biofunctionalization protocol based on chemical surface modification through silane chemistry on SiO₂ optical sensing transducers. Even though silane chemistry is commonly used for sensing applications, here we present a different mode of operation, applying an unusual silane compound used for this purpose (3-Ethoxydimethylsilyl)propylamine, APDMS, able to create ordered monolayers, and minimizing fouling events. To endorse this protocol as a feasible method for biofunctionalization, we performed multiple surface characterization techniques after all the process steps: Contact angle (CA), X-ray photoelectron spectroscopy (XPS), ellipsometry, and fluorescence microscopy. Finally, to evidence the outputs from the SiO₂ surface characterization, we used those SiO₂ surfaces as optical transducers for the label-free biosensing of matrix metalloproteinase 9 (MMP9). We found and demonstrated that the originally designed protocol is reproducible, stable, and suitable for SiO2-based optical sensing transducers.

De Novo Synthesis of Elastin-like Polypeptides (ELPs): An Applied Overview on the Current Experimental Techniques

Elastin-like polypeptides (ELPs) are protein-based biopolymers genetically produced from polypeptides composed of a repeating pentapeptide sequence V-P-G-X-G. The inherent properties of recombinant ELPs, such as smart nature, controlled sequence complexity, physicochemical properties, and biocompatibility, make these polymers suitable for use in nanobiotechnological applications, as biofunctionalized scaffolds for tissue-engineering purposes and drug delivery. In this work, we report the design and synthesis of two elastomeric self-assembling polypeptides (ELPs) that mimic the endogenous human tropoelastin. Using molecular biology techniques, two artificial genes that encode two ELP concatemers of approximate molecular mass 60 kDa, one of them carrying biotin-binding peptide motifs, were constructed. These motifs could facilitate biofunctionalization of the ELPs through tethering biotinylated factors, such as growth factors. The ELPs were heterologously overexpressed in E. coli and subsequently purified in two steps: a nonchromatographic technique by organic solvent extraction, followed by nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography. The characterization of the biochemical properties and biocompatibility of ELPs was also performed in this study. The ELP carrying the biotin-binding motifs was tested for its capability to bind biotin, and indeed, it was observed that it can bind biotinylated proteins specifically. Additionally, results concerning the cytotoxicity of the ELPs exhibited excellent compatibility of the ELPs with mammalian cells in vitro. We anticipate that these ELPs can be used as components of a scaffold that mimics the extracellular matrix (ECM) for the regeneration of endogenously highly elastic tissues.

Immunosensing Based on Optical Fiber Technology: Recent Advances

The evolution of optical fiber technology has revolutionized a variety of fields, from optical transmission to environmental monitoring and biomedicine, given their unique properties and versatility. For biosensing purposes, the light guided in the fiber core is exposed to the surrounding media where the analytes of interest are detected by different techniques, according to the optical fiber configuration and biofunctionalization strategy employed. These configurations differ in manufacturing complexity, cost and overall performance. The biofunctionalization strategies can be carried out directly on bare fibers or on coated fibers. The former relies on interactions between the evanescent wave (EW) of the fiber and the analyte of interest, whereas the latter can comprise plasmonic methods such as surface plasmon resonance (SPR) and localized SPR (LSPR), both originating from the interaction between light and metal surface electrons. This review presents the basics of optical fiber immunosensors for a broad audience as well as the more recent research trends on the topic. Several optical fiber configurations used for biosensing applications are highlighted, namely uncladded, U-shape, D-shape, tapered, end-face reflected, fiber gratings and special optical fibers, alongside practical application examples. Furthermore, EW, SPR, LSPR and biofunctionalization strategies, as well as the most recent advances and applications of immunosensors, are also covered. Finally, the main challenges and an outlook over the future direction of the field is presented.

Enhanced vascularization andde novotissue formation in hydrogels made of engineered RGD-tagged spider silk proteins in the arteriovenous loop model

Due to its low immunogenic potential and the possibility to fine-tune their properties, materials made of recombinant engineered spider silks are promising candidates for tissue engineering applications. However, vascularization of silk-based scaffolds is one critical step for the generation of bioartificial tissues and consequently for clinical application. To circumvent insufficient vascularization, the surgically induced angiogenesis by means of arteriovenous loops (AVL) represents a highly effective methodology. Here, previously established hydrogels consisting of nano-fibrillary recombinant eADF4(C16) were transferred into Teflon isolation chambers and vascularized in the rat AVL model over 4 weeks. To improve vascularization, also RGD-tagged eADF4(C16) hydrogels were implanted in the AVL model over 2 and 4 weeks. Thereafter, the specimen were explanted and analyzed using histology and microcomputed tomography. We were able to confirm biocompatibility and tissue formation over time. Functionalizing eADF4(C16) with RGD-motifs improved hydrogel stability and enhanced vascularization even outperforming other hydrogels, such as fibrin. This study demonstrates that the scaffold ultrastructure as well as biofunctionalization with RGD-motifs are powerful tools to optimize silk-based biomaterials for tissue engineering applications.

Poly(catecholamine) coated CsPbBr3 perovskite microlasers: lasing in water and biofunctionalization

Lead halide perovskite (LHP) is a promising material for various optoelectronic applications. Surface coating on particles is a common strategy to improve their functionality and environmental stability, but LHP is not amenable to most coating chemistries because of its intrinsic weakness against polar solvents. Here, we describe a novel method of synthesizing LHP microlasers in a super-saturated polar solvent using sonochemistry and applying various functional coatings on individual microlasers in situ. We synthesize cesium lead bromine perovskite (CsPbBr3) microcrystals capped with organic poly-norepinephrine (pNE) layers. The catechol group of pNE coordinates to bromine-deficient lead atoms, forming a defect-passivating and diffusion-blocking shell. The pNE layer enhances the material lifetime of CsPbBr3 in water by 2,000-folds, enabling bright luminescence and lasing from single microcrystals in water. Furthermore, the pNE shell permits biofunctionalization with proteins, small molecules, and lipid bilayers. Luminescence from CsPbBr3 microcrystals is sustained in water over 1 hour and observed in live cells. The functionalization method may enable new applications of LHP laser particles in water-rich environments.

Click-Coupling to Electrostatically Grafted Polymers Greatly Improves the Stability of a Continuous Monitoring Sensor with Single-Molecule Resolution

Sensing technologies for the real-time monitoring of biomolecules will allow studies of dynamic changes in biological systems and the development of control strategies based on measured responses. Here, we describe a molecular architecture and coupling process that allow continuous measurements of low-concentration biomolecules over long durations in a sensing technology with single-molecule resolution. The sensor is based on measuring temporal changes of the motion of particles upon binding and unbinding of analyte molecules. The biofunctionalization involves covalent coupling by click chemistry to PLL-g-PEG bottlebrush polymers. The polymer is grafted to a surface by multivalent electrostatic interactions, while the poly(ethylene glycol) suppresses nonspecific binding of biomolecules. With this biofunctionalization strategy, we demonstrate the continuous monitoring of single-stranded DNA and a medically relevant small-molecule analyte (creatinine), in sandwich and competitive assays, in buffer and in filtered blood plasma, with picomolar, nanomolar, and micromolar analyte concentrations, and with continuous sensor operation over 10 h.

The Influence of Hyaluronic Acid Biofunctionalization of a Bovine Bone Substitute on Osteoblast Activity In Vitro

Bovine bone substitute materials (BSMs) are used for oral bone regeneration. The objective was to analyze the influence of BSM biofunctionalization via hyaluronic acid (HA) on human osteoblasts (HOBs). BSMs with ± HA were incubated with HOBs including HOBs alone as a negative control. On days 3, 7 and 10, cell viability, migration and proliferation were analyzed by fluorescence staining, scratch wound assay and MTT assay. On days 3, 7 and 10, an increased cell viability was demonstrated for BSM+ compared with BSM− and the control (each p ≤ 0.05). The cell migration was enhanced for BSM+ compared with BSM− and the control after day 3 and day 7 (each p ≤ 0.05). At day 10, an accelerated wound closure was found for the control compared with BSM+/− (each p < 0.05). The highest proliferation rate was observed for BSM+ on day 3 (p ≤ 0.05) followed by BSM− and the control (each p ≤ 0.05). At day 7, a non-significantly increased proliferation was shown for BSM+ while the control was higher than BSM− (each p < 0.05). The least proliferation activity was observed for BSM− (p < 0.05) at day 10. HA biofunctionalization of the BSMs caused an increased HOB activity and might represent a promising alternative to BSM− in oral bone regeneration.

Antibody-Functionalized Nanowires: A Tuner for the Activation of T Cells

T cells sense both chemical cues delivered by antigen molecules and physical cues delivered by the environmental elasticity and topography; yet, it is still largely unclear how these cues cumulatively regulate the immune activity of T cells. Here, we engineered a nanoscale platform for ex vivo stimulation of T cells based on antigen-functionalized nanowires. The nanowire topography and elasticity, as well as the immobilized antigens, deliver the physical and chemical cues, respectively, enabling the systematic study of the integrated effect of these cues on a T cell's immune response. We found that T cells sense both the topography and bending modulus of the nanowires and modulate their signaling, degranulation, and cytotoxicity with the variation in these physical features. Our study provides an important insight into the physical mechanism of T cell activation and paves the way to novel nanomaterials for the controlled ex vivo activation of T cells in immunotherapy.

Nanowire Based Guidance of the Morphology and Cytotoxic Activity of Natural Killer Cells

The cytotoxic activity of natural killer (NK) cells is regulated by many chemical and physical cues, whose integration mechanism is still obscure. Here, a multifunctional platform is engineered for NK cell stimulation, to study the effect of the signal integration and spatial heterogeneity on NK cell function. The platform is based on nanowires, whose mechanical compliance and site-selective tip functionalization with antigens produce the physical and chemical stimuli, respectively. The nanowires are confined to micron-sized islands, which induce a splitting of the NK cells into two subpopulations with distinct morphologies and immune responses: NK cells atop the nanowire islands display symmetrical spreading and enhanced activation, whereas cells lying in the straits between the islands develop elongated profiles and show lower activation levels. The demonstrated tunability of NK cell cytotoxicity provides an important insight into the mechanism of their immune function and introduces a novel technological route for the ex vivo shaping of cytotoxic lymphocytes in immunotherapy.

Optimization of Glutathione Adhesion Process to Modified Graphene Surfaces

The presented work shows the results of the functionalization of the graphene surface obtained by the growth on the liquid bimetallic matrices method. We used glutathione (GSH) as a peptide model, which allowed us to optimize the procedure to obtain high process efficiency. To establish the amount of GSH attached to the graphene surface, the Folina-Ciocalteu method was used, which allows the assessment of the concentration of colored reaction products with peptide bonds without the disadvantages of most methods based on direct colored reaction of peptide bonds. Samples surface morphology, quality of graphene and chemical structure in the subsequent stages of surface modification were tested-for this purpose Raman spectroscopy, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) were used.

Biomimetic Culture Strategies for the Clinical Expansion of Mesenchymal Stromal Cells

Mesenchymal stromal/stem cells (MSCs) typically require significant ex vivo expansion to achieve the high cell numbers required for research and clinical applications. However, conventional MSC culture on planar (2D) plastic surfaces has been shown to induce MSC senescence and decrease cell functionality over long-term proliferation, and usually, it has a high labor requirement, a high usage of reagents, and therefore, a high cost. In this Review, we describe current MSC-based therapeutic strategies and outline the important factors that need to be considered when developing next-generation cell expansion platforms. To retain the functional value of expanded MSCs, ex vivo culture systems should ideally recapitulate the components of the native stem cell microenvironment, which include soluble cues, resident cells, and the extracellular matrix substrate. We review the interplay between these stem cell niche components and their biological roles in governing MSC phenotype and functionality. We discuss current biomimetic strategies of incorporating biochemical and biophysical cues in MSC culture platforms to grow clinically relevant cell numbers while preserving cell potency and stemness. This Review summarizes the current state of MSC expansion technologies and the challenges that still need to be overcome for MSC clinical applications to be feasible and sustainable.

How Reactivity Variability of Biofunctionalized Particles Is Determined by Superpositional Heterogeneities

The biofunctionalization of particles with specific targeting moieties forms the foundation for molecular recognition in biomedical applications such as targeted nanomedicine and particle-based biosensing. To achieve a high precision of targeting for nanomedicine and high precision of sensing for biosensing, it is important to understand the consequences of heterogeneities of particle properties. Here, we present a comprehensive methodology to study with experiments and simulations the collective consequences of particle heterogeneities on multiple length scales, called superpositional heterogeneities, in generating reactivity variability per particle. Single-molecule techniques are used to quantify stochastic, interparticle, and intraparticle variabilities, in order to show how these variabilities collectively contribute to reactivity variability per particle, and how the influence of each contributor changes as a function of the system parameters such as particle interaction area, the particle size, the targeting moiety density, and the number of particles. The results give insights into the consequences of superpositional heterogeneities for the reactivity variability in biomedical applications and give guidelines on how the precision can be optimized in the presence of multiple independent sources of variability.

Biofunctionalization of Water-Soluble poly(Phenylene Ethynylene)s

We report the use of amide coupling chemistry to covalently link five different biofunctional groups onto an anionic water-soluble poly(phenylene ethynylene) (PPE) polymer. Two of the biofunctionalized PPEs are used in prototype applications, including pH sensing and flow cytometry labeling. The PPE is functionalized with carboxylate (R-CO2-) and sulfonate (R-SO3-) ionic groups. By using an activated ester, the amine-functionalized groups are covalently linked to the PPE polymer via amide linkages. The reaction chemistry is optimized using biotin-ethylene diamine, making it possible to control the loading of the biotin functionality on the PPE chains. Using the optimized approach, a family of five PPEs were prepared that contain biotin, rhodamine, cholesterol, mannose, or folic acid moieties appended to the polymer backbones. The rhodamine- and biotin-modified PPEs were further applied for pH response and flow cytometry applications. The reported approach can be utilized for other classes of water-soluble conjugated polymers, allowing facile development of a variety of new functionalized water-soluble conjugated polymers for a range of applications including sensing, bioimaging, and flow cytometry analysis.

Smart ECM-Based Electrospun Biomaterials for Skeletal Muscle Regeneration

The development of smart and intelligent regenerative biomaterials for skeletal muscle tissue engineering is an ongoing challenge, owing to the requirement of achieving biomimetic systems able to communicate biological signals and thus promote optimal tissue regeneration. Electrospinning is a well-known technique to produce fibers that mimic the three dimensional microstructural arrangements, down to nanoscale and the properties of the extracellular matrix fibers. Natural and synthetic polymers are used in the electrospinning process; moreover, a blend of them provides composite materials that have demonstrated the potential advantage of supporting cell function and adhesion. Recently, the decellularized extracellular matrix (dECM), which is the noncellular component of tissue that retains relevant biological cues for cells, has been evaluated as a starting biomaterial to realize composite electrospun constructs. The properties of the electrospun systems can be further improved with innovative procedures of functionalization with biomolecules. Among the various approaches, great attention is devoted to the "click" concept in constructing a bioactive system, due to the modularity, orthogonality, and simplicity features of the "click" reactions. In this paper, we first provide an overview of current approaches that can be used to obtain biofunctional composite electrospun biomaterials. Finally, we propose a design of composite electrospun biomaterials suitable for skeletal muscle tissue regeneration.

Hydrofluoric acid and nitric acid cotreatment for biofunctionalization of polyetheretherketone in M2 macrophage polarization and osteogenesis

Due to its excellent mechanical and low-friction properties, polyetheretherketone (PEEK) has been widely investigated for use in orthopedic applications over the past decade. However, the bioinertness and poor osteogenic properties of PEEK have hampered its clinical application. In this study, the surface of PEEK was modified by co-treatment with hydrofluoric acid and nitric acid (AFN). The microstructures of the modified PEEK surfaces were investigated using scanning electron microscopy. The water contact angles of the surfaces were also measured. To evaluate their cytocompatibility, PEEK samples were used as substrates to culture rat bone mesenchymal stem cells, and cell adhesion, viability, and expression of specific marker genes were measured. Treatment of PEEK with AFN (PEEK-AFN) was found to enable better osteoblast adhesion, spreading, and proliferation; the activity of alkaline phosphatase (an early osteogenic differentiation marker) was also found to be enhanced post-treatment. Furthermore, PEEK-AFN was able to modulate macrophage polarization and down regulated the expression of proinflammatory factors via inhibiting the NF-κB pathway. Thus, treatment of PEEK with AFN could promote M2 polarization of the macrophages and stimulate the differentiation of osteoblasts. These results provide valuable information that could facilitate the use of PEEK-based composites as bone implant materials.

Modulating Alginate Hydrogels for Improved Biological Performance as Cellular 3D Microenvironments

The rational choice and design of biomaterials for biomedical applications is crucial for successful in vitro and in vivo strategies, ultimately dictating their performance and potential clinical applications. Alginate, a marine-derived polysaccharide obtained from seaweeds, is one of the most widely used polymers in the biomedical field, particularly to build three dimensional (3D) systems for in vitro culture and in vivo delivery of cells. Despite their biocompatibility, alginate hydrogels often require modifications to improve their biological activity, namely via inclusion of mammalian cell-interactive domains and fine-tuning of mechanical properties. These modifications enable the addition of new features for greater versatility and control over alginate-based systems, extending the plethora of applications and procedures where they can be used. Additionally, hybrid systems based on alginate combination with other components can also be explored to improve the mimicry of extracellular microenvironments and their dynamics. This review provides an overview on alginate properties and current clinical applications, along with different strategies that have been reported to improve alginate hydrogels performance as 3D matrices and 4D dynamic systems.

DNA-Biofunctionalization of CTAC-Capped Gold Nanocubes

Clinical diagnostics and disease control are fields that strongly depend on technologies for rapid, sensitive, and selective detection of biological or chemical analytes. Nanoparticles have become an integral part in various biomedical detection devices and nanotherapeutics. An increasing focus is laid on gold nanoparticles as they express less cytotoxicity, high stability, and hold unique optical properties with the ability of signal transduction of biological recognition events with enhanced analytical performance. Strong electromagnetic field enhancements can be found in close proximity to the nanoparticle that can be exploited to enhance signals for e.g., metal-enhanced fluorescence or Raman spectroscopy. Even stronger field enhancements can be achieved with sharp-edged nanoparticles, which are synthesized with the help of facet blocking agents, such as cetyltrimethylammonium bromide/chloride (CTAB/CTAC). However, chemical modification of the nanoparticle surface is necessary to reduce the particle’s cytotoxicity, stabilize it against aggregation, and to bioconjugate it with biomolecules to increase its biocompatibility and/or specificity for analytical applications. Here, a reliable two-step protocol following a ligand exchange with bis (p-sulfonatophenyl) phenyl phosphine (BSPP) as the intermediate capping-agent is demonstrated, which results in the reliable biofunctionalization of CTAC-capped gold nanocubes with thiol-modified DNA. The functionalized nanocubes have been characterized regarding their electric potential, plasmonic properties, and stability against high concentrations of NaCl and MgCl₂.

Multifunctional Biomaterials: Combining Material Modification Strategies for Engineering of Cell-Contacting Surfaces

In the human body, cells in a tissue are exposed to signals derived from their specific extracellular matrix (ECM), such as architectural structure, mechanical properties, and chemical composition (proteins, growth factors). Research on biomaterials in tissue engineering and regenerative medicine aims to recreate such stimuli using engineered materials to induce a specific response of cells at the interface. Although traditional biomaterials design has been mostly limited to varying individual signals, increasing interest has arisen on combining several features in recent years to improve the mimicry of extracellular matrix properties. Tremendous progress in combinatorial surface modification exploiting, for example, topographical features or variations in mechanics combined with biochemical cues has enabled the identification of their key regulatory characteristics on various cell fate decisions. Gradients especially facilitated such research by enabling the investigation of combined continuous changes of different signals. Despite unravelling important synergies for cellular responses, challenges arise in terms of fabrication and characterization of multifunctional engineered materials. This review summarizes recent work on combinatorial surface modifications that aim to control biological responses. Modification and characterization methods for enhanced control over multifunctional material properties are highlighted and discussed. Thereby, this review deepens the understanding and knowledge of biomimetic combinatorial material modification, their challenges but especially their potential.

Polycaprolactone Films Modified by L-Arginine for Mesenchymal Stem Cell Cultivation

This article describes the modification conditions and properties of polymer films obtained using a solution of poly(ε-caprolactone) modified with arginine. We investigated the effects on the surface and biological properties of films created using various arginine concentrations and temperature conditions during the modification process. We found that both increasing the arginine concentration of the treatment solution or the temperature of the treatment reaction increased the arginine content of the film. Following a cellular cultivation period of 3 days, greater levels of cell proliferation were observed on all modified poly(ε-caprolactone) films compared to unmodified polymer films. Experiments using fluorescence microscopy showed that the modification conditions also had a significant effect on cellular spreading and the organization of the actin cytoskeleton following 2 h of cultivation. The degree of spreading and actin cytoskeleton organization observed in cells on these modified polymer films was superior to that of the control films.