Surface Functionalization of Ti6Al4V via Self-assembled Monolayers for Improved Protein Adsorption and Fibroblast Adhesion

Mixed Functional Siloxane Monolayers Prepared via Chemical Vapor Deposition

Functionalizing surfaces with self-assembled monolayers (SAMs) allows to efficiently bind bioreceptors, for instance, by bio-orthogonal click reactions, which is useful in biosensor fabrication. Control of the bioreceptor concentration on the surface can be achieved by coating an SAM mixture consisting of a functional SAM, which binds the bioreceptor, and a nonfunctional SAM for dilution. In this work, a novel vapor-based coating approach for the preparation of mixed SAM coatings is presented. Sequential evaporation of the SAM precursors, i.e., fluoroalkyl and azidoalkyl silanes, by heating under reduced pressure leads to the formation of a two-dimensional siloxane monolayer network on silicon oxide. The presence of both SAMs in the mixed coatings is confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. As verified by atomic force microscopy, the morphologies of the coatings and the uncoated silicon oxide substrates are similar, indicating a conformal coating. Functionality of the SAM mixture is demonstrated by a reaction with a fluorescent dye, illustrating its potential application in biosensors.

Osteointegration of Ti Bone Implants: A Study on How Surface Parameters Control the Foreign Body Response

The integration of titanium (Ti)-based implants with bone is limited, resulting in implant failure. This lack of osteointegration is due to the foreign body response (FBR) that occurs after the implantation of biodevices. The process begins with protein adsorption, which is governed by implant surface properties, e.g., chemistry, charge, wettability, and/or topography. The distribution and composition of the protein layer in turn influence the recruitment, differentiation, and modulation of immune and bone cells. The subsequent events that occur at the bone-material interface will ultimately determine whether the implant is encapsulated or will integrate with bone. Despite the numerous studies evaluating the influence of surface properties in the various stages of the FBR, the factors that affect tissue-material interactions are often studied in isolation or in small correlations due to the technical challenges involved in assessing them in vitro or in vivo. Consequently, the influence of protein conformation on the Ti bone implant surface design remains an unresolved research question. The objective of this review is to comprehensively evaluate the existing literature on the effect of surface parameters of Ti and its alloys in the stages of FBR, with a particular focus on protein adsorption and osteoimmunomodulation. This evaluation aims to systematically describe these effects on bone formation.

Transglutaminase enables highly hydrolytically and proteolytically stable crosslinking of collagen on titanium surfaces and promotes osteogenic differentiation of human mesenchymal stem cells

Collagen with its bioactive ligand motives would be predestined as coating on bone implant surfaces like titanium hip stems to facilitate receptor-mediated cell adhesion and thereby improve early osseointegration. Unfortunately, collagen as coating exhibits very low proteolytic resistance in vivo. To overcome this limitation, different crosslinking methods of collagen (transglutaminase, GTA, EDC/NHS, riboflavin, and lysyl oxidase) with silanized titanium alloy (Ti6Al4V) were investigated in terms of degradation resistance, hydrolysis stability, tensile strength, and metabolic cell activity. The in vitro osteogenic differentiation ability of human mesenchymal stem cells (hMSCs) induced by the surface modification was evaluated by immunofluorescence of early osteogenic markers, Alizarin red staining, and energy dispersive X-ray spectroscopy. The expression of the adhesion-related protein vinculin was analyzed on the different functionalized surfaces. The results revealed that the enzymatic crosslinker transglutaminase offered high degradation resistance, tensile strength, and hydrolysis stability compared to the other crosslinking reagents tested. Remarkably, the adhesion sequences within the collagen were accessible to the hMSCs despite the transglutaminase crosslinking procedure. In conclusion, the organochemical functionalization of Ti6Al4V surfaces with collagen using transglutaminase holds great potential to facilitate an enhanced interaction with attached bone cells and thereby could potentially improve and accelerate osseointegration of a titanium-based bone implant in vivo.

Increasing the sensitivity and accuracy of detecting exosomes as biomarkers for cancer monitoring using optical nanobiosensors

The advancement of nanoscience and material design in recent times has facilitated the creation of point-of-care devices for cancer diagnosis and biomolecule sensing. Exosomes (EXOs) facilitate the transfer of bioactive molecules between cancer cells and diverse cells in the local and distant microenvironments, thereby contributing to cancer progression and metastasis. Specifically, EXOs derived from cancer are likely to function as biomarkers for early cancer detection due to the genetic or signaling alterations they transport as payload within the cancer cells of origin. It has been verified that EXOs circulate steadily in bodily secretions and contain a variety of information that indicates the progression of the tumor. However, acquiring molecular information and interactions regarding EXOs has presented significant technical challenges due to their nanoscale nature and high heterogeneity. Colorimetry, surface plasmon resonance (SPR), fluorescence, and Raman scattering are examples of optical techniques utilized to quantify cancer exosomal biomarkers, including lipids, proteins, RNA, and DNA. Many optically active nanoparticles (NPs), predominantly carbon-based, inorganic, organic, and composite-based nanomaterials, have been employed in biosensing technology. The exceptional physical properties exhibited by nanomaterials, including carbon NPs, noble metal NPs, and magnetic NPs, have facilitated significant progress in the development of optical nanobiosensors intended for the detection of EXOs originating from tumors. Following a summary of the biogenesis, biological functions, and biomarker value of known EXOs, this article provides an update on the detection methodologies currently under investigation. In conclusion, we propose some potential enhancements to optical biosensors utilized in detecting EXO, utilizing various NP materials such as silicon NPs, graphene oxide (GO), metal NPs, and quantum dots (QDs).

Biocompatible antibiotic-coupled nickel-titanium nanoparticles as a potential coating material for biomedical devices

The challenges facing metallic implants for reconstructive surgery include the leaching of toxic metal ions, a mismatch in elastic modulus between the implant and the treated tissue, and the risk of infection. These problems can be addressed by passivating the metal surface with an organic substrate and incorporating antibiotic molecules. Nitinol (NiTi), a nickel-titanium alloy, is used in devices for biomedical applications due to its shape memory and superelasticity. However, unmodified NiTi carries a risk of localized nickel toxicity and inadequately supports angiogenesis or neuroregeneration due to limited cell adhesion, poor biomineralization, and little antibacterial activity. To address these challenges, NiTi nanoparticles were modified using self-assembled phosphonic acid monolayers and functionalized with the antibiotics ceftriaxone and vancomycin via the formation of an amide. Surface modifications were monitored to confirm that phosphonic acid modifications were present on NiTi nanoparticles and 100% of the samples formed ordered films. Modifications were stable for more than a year. Elemental composition showed the presence of nickel, titanium, and phosphorus (1.9% for each sample) after surface modifications. Dynamic light scattering analysis suggested some agglomeration in solution. However, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy confirmed a particle size distribution of <100 nm, the even distribution of nanoparticles on coverslips, and elemental composition before and after cell culture. B35 neuroblastoma cells exhibited no inhibition of survival and extended neurites of approximately 100 μm in total length when cultured on coverslips coated with only poly-l-lysine or with phosphonic acid-modified NiTi, indicating high biocompatibility. The ability to support neural cell growth and differentiation makes modified NiTi nanoparticles a promising coating for surfaces in metallic bone and nerve implants. NiTi nanoparticles functionalized with ceftriaxone inhibited Escherichia coli and Serratia marcescens (SM6) at doses of 375 and 750 μg whereas the growth of Bacillus subtilis was inhibited by a dose of only 37.5 μg. NiTi-vancomycin was effective against B. subtilis at all doses even after mammalian cell culture. These are common bacteria associated with infected implants, further supporting the potential use of functionalized NiTi in coating reconstructive implants.

Construction of chitosan-gelatin polysaccharide-protein composite hydrogel via mechanical stretching and its biocompatibility in vivo

Natural polysaccharides and protein macromolecules are the important components of extracellular matrix (ECM), but individual component generally exhibits weak mechanical property, limited biological function or strong immunogenicity in tissue engineering. Herein, gelatin (Gel) was deposited to the stretched (65 %) chitosan (CS) hydrogel substrates to fabricate the polysaccharide-protein CS-Gel-65 % composite hydrogels to mimic the natural component of ECM and improve the above deficiencies. CS hydrogel substrates under different stretching deformations exhibited tunable morphology, chemical property and wettability, having a vital influence on the secondary structures of deposited fibrous Gel protein, namely appearing with the decreased β-sheet content in stretched CS hydrogel. Gel also produced a more homogenous distribution on the stretched CS hydrogel substrate due to the unfolding of Gel and increased interactions between Gel and CS than on the unstretched substrate. Moreover, the polysaccharide-protein composite hydrogel possessed enhanced mechanical property and oriented structure via stretching-drying method. Besides, in vivo subcutaneous implantation indicated that the CS-Gel-65 % composite hydrogel showed lower immunogenicity, thinner fibrous capsule, better angiogenesis effect and increased M2/M1 of macrophage phenotype. Polysaccharide-protein CS-Gel-65 % composite hydrogel offers a novel material as a tissue engineering scaffold, which could promote angiogenesis and build a good immune microenvironment for the damaged tissue repair.

Functionalization of a zirconia surface by covalently immobilized fibronectin and its effects on resistance to thermal, acid, and mechanical exposure

Silane chemistry has emerged as a powerful tool for surface modification, offering a versatile means to enhance the properties of various substrates, such as dental implant abutment materials. In this study, we investigated the stability of the 3-aminopropyldiisopropylethoxysilane (APDS) layer on yttria-partially stabilized zirconia (Y-TZP) surfaces after mechanical, acid, and thermal treatment in order to simulate fluctuations within the oral cavity. To accomplish that, the viability of human gingival fibroblasts on APDS-modified surfaces after applied treatment strategies was assessed by live/dead staining. Moreover, the hydrolysis stability and enzymatic degradation resistance of crosslinked fibronectin to the APDS layer was examined by immunostaining and western blot. The results revealed that the applied modifications were not affected by the different treatment conditions and could withstand the fluctuations in the oral cavity. Furthermore, crosslinked fibronectin on silanized Y-TZP was stable against hydrolysis over 21 days and enzymatic degradation. We thus can conclude that the proposed functionalization method has high potential to tolerate harmful effects within the oral cavity and remains unchanged on the surface.

Exploring Multifunctional Response of Ca10(PO4)6(OH)2-K0.5Na0.5NbO3 Ceramic Composite for Biomedical Applications

This study focuses on investigating the intriguing properties of Ca10(PO4)6(OH)2 (HAP)-K0.5Na0.5NbO3 (KNN) bioceramic composites, seeking to elucidate the relationship between their structural, electrical, biological, and optical behavior. The article begins with a close inspection of the O 1s spectra of the specimens obtained from X-ray photoelectron spectroscopy (XPS). The spectra reveal the peak related to lattice oxygen, O vacancy and the surface adsorbed O. The formed O vacancy strongly influences the changes in lattice parameters as observed from the X-ray diffraction (XRD) patterns. The frequency variation of the dielectric response for the composites in the radio frequency (RF) regime has electrical polarization effective for biomedical applications. Nyquist plots along with equivalent RC circuits further confirm that those electrical responses are mainly contributed from the grain boundaries. Adsorption dynamics of protein on the ceramic surface are investigated using bovine serum albumin (BSA), which established the major role of electrostatic interaction. Surface charge and O vacancies are modeled to understand the adsorption of protein and a linear correlation is reported. The role of O vacancies in modulating adsorption dynamics adds a new dimension to this study. The conformational change of BSA has also been considered by constructing the secondary structure following the protein-ceramic interaction. Excitingly, the composites are also found to be fluorescent active, a courtesy of the defects and vacancies leading to electron-hole recombination in the forbidden region. These promising properties envision an exciting future for HAP-KNN composites, especially in the domain of bioimaging and bone-tissue engineering.

Biogenesis, Isolation, and Detection of Exosomes and Their Potential in Therapeutics and Diagnostics

The increasing research and rapid developments in the field of exosomes provide insights into their role and significance in human health. Exosomes derived from various sources, such as mesenchymal stem cells, cardiac cells, and tumor cells, to name a few, can be potential therapeutic agents for the treatment of diseases and could also serve as biomarkers for the early detection of diseases. Cellular components of exosomes, several proteins, lipids, and miRNAs hold promise as novel biomarkers for the detection of various diseases. The structure of exosomes enables them as drug delivery vehicles. Since exosomes exhibit potential therapeutic applications, their efficient isolation from complex biological/clinical samples and precise real-time analysis becomes significant. With the advent of microfluidics, nano-biosensors are being designed to capture exosomes efficiently and rapidly. Herein, we have summarized the history, biogenesis, characteristics, functions, and applications of exosomes, along with the isolation, detection, and quantification techniques. The implications of surface modifications to enhance specificity have been outlined. The review also sheds light on the engineered nanoplatforms being developed for exosome detection and capture.

Surface modifications of biomaterials in different applied fields

Biomaterial implantation into the human body plays a key role in the medical field and biological applications. Increasing the life expectancy of biomaterial implants, reducing the rejection reaction inside the human body and reducing the risk of infection are the problems in this field that need to be solved urgently. The surface modification of biomaterials can change the original physical, chemical and biological properties and improve the function of materials. This review focuses on the application of surface modification techniques in various fields of biomaterials reported in the past few years. The surface modification techniques include film and coating synthesis, covalent grafting, self-assembled monolayers (SAMs), plasma surface modification and other strategies. First, a brief introduction to these surface modification techniques for biomaterials is given. Subsequently, the review focuses on how these techniques change the properties of biomaterials, and evaluates the effects of modification on the cytocompatibility, antibacterial, antifouling and surface hydrophobic properties of biomaterials. In addition, the implications for the design of biomaterials with different functions are discussed. Finally, based on this review, it is expected that the biomaterials have development prospects in the medical field.

Implant surface physicochemistry affects keratinocyte hemidesmosome formation

Previous studies have shown hydrophilic/hydrophobic implant surfaces stimulate/hinder osseointegration. An analogous concept was applied here using common biological functional groups on a model surface to promote oral keratinocytes (OKs) proliferation and hemidesmosomes (HD) to extend implant lifespans through increased soft tissue attachment. However, it is unclear what physicochemistry stimulates HDs. Thus, common biological functional groups (NH2 , OH, and CH3 ) were functionalized on glass using silanization. Non-functionalized plasma-cleaned glass and H silanization were controls. Surface modifications were confirmed with X-ray photoelectron spectroscopy and water contact angle. The amount of bovine serum albumin (BSA) and fibrinogen, and BSA thickness, were assessed to understand how adsorbed protein properties were influenced by physicochemistry and may influence HDs. OKs proliferation was measured, and HDs were quantified with immunofluorescence for collagen XVII and integrin β4. Plasma-cleaned surfaces were the most hydrophilic group overall, while CH3 was the most hydrophobic and OH was the most hydrophilic among functionalized groups. Modification with the OH chemical group showed the highest OKs proliferation and HD expression. The OKs response on OH surfaces appeared to not correlate to the amount or thickness of adsorbed model proteins. These results reveal relevant surface physicochemical features to favor HDs and improve implant soft tissue attachment.

Manganese supplementation of orthopedic implants: a new strategy for enhancing integrin-mediated cellular responses

Integrin-mediated osteoblast adhesion to adsorbed extracellular ligands on orthopedic implants is crucial for the subsequent osteoblast behaviors and ultimate osseointegration. Considerable research efforts have focused on the development of implant surfaces that promote the adsorption of extracellular ligands, but ignored the fact that integrin binding to ligands requires divalent cations (such as Mn²⁺). Here, three kinds of Mn-doped nanowire-structured TiO₂ coatings with 1.9, 3.9, and 8.8 wt% dopant contents (Mn1-, Mn2-, and Mn3-TiO₂) were synthesized on Ti implants to enhance integrin-mediated osteoblastic responses. The Mg-doped and undoped TiO₂ nanocoatings served as the control. Mn element was not only successfully incorporated into the TiO₂ matrix, but also formed an oxygen-deficient Mn oxide on the nanowire surface. Although the adsorbed fibronectin (Fn) amount on Mn-doped nanocoatings and its unfolded status were slightly attenuated with increasing Mn amount, the interaction between the coating extract and Fn demonstrated a Mn²⁺-induced unfolding of Fn with the exposure of the RGD motif. Compared to the Mn1-, Mn2- and Mg-doped TiO₂ nanocoatings, the Mn3-TiO₂ nanocoating significantly upregulated the expression of integrin α5β1 probably through increasing the ligand-binding affinity of the integrin rather than integrin binding sites in Fn. Consistent with the activation trend of integrin α5β1, the Mn3-TiO₂ nanocoating enhanced cell adhesion with the long stretched structure of actin fibers and extensive formation of vinculin focal adhesion spots and upregulated the levels of alkaline phosphatase and osteocalcin activities. Therefore, Mn supplementation of orthopedic implants may be a promising way to improve osteogenesis at the implant surface.

Unfolding of the SARS-CoV-2 spike protein through infrared and ultraviolet-C radiation based disinfection

The spreading of coronavirus from contacting surfaces and aerosols created a pandemic around the world. To prevent the transmission of SARS-CoV-2 virus and other contagious microbes, disinfection of contacting surfaces is necessary. In this study, a disinfection box equipped with infrared (IR) radiation heating and ultraviolet-C (UV-C) radiation is designed and tested for its disinfection ability against pathogenic bacteria and SARS-CoV-2 spike protein. The killing of a Gram-positive, namely, S. aureus and a Gram-negative namely, S. typhi bacteria was studied followed by the inactivation of the spike protein. The experimental parameters were optimized using a statistical tool. For the broad-spectrum antibacterial activity, the optimum condition was holding at 65.61 °C for 13.54 min. The killing of the bacterial pathogen occurred via rupturing the cell walls as depicted by electron microscopy. Further, the unfolding of SARS-CoV-2 spike protein and RNase A was studied under IR and UV-C irradiations at the aforesaid optimized condition. The unfolding of both the proteins was confirmed by changes in the secondary structure, particularly an increase in β-sheets and a decrease in α-helixes. Remarkably, the higher penetration depth of IR waves up to subcutaneous tissue resulted in lower optimum disinfection temperature, <70 °C in vogue. Thus, the combined UV-C and IR radiation is effective in killing the pathogenic bacteria and denaturing the glycoproteins.

Surface Texturing and Combinatorial Approaches to Improve Biocompatibility of Implanted Biomaterials

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

Chitosan-based films with cannabis oil as a base material for wound dressing application

This study focuses on obtaining and characterizing novel chitosan-based biomaterials containing cannabis oil to potentially promote wound healing. The primary active substance in cannabis oil is the non-psychoactive cannabidiol, which has many beneficial properties. In this study, three chitosan-based films containing different concentrations of cannabis oil were prepared. As the amount of oil increased, the obtained biomaterials became rougher as tested by atomic force microscopy. Such rough surfaces promote protein adsorption, confirmed by experiments assessing the interaction between human albumin with the obtained materials. Increased oil concentration also improved the films' mechanical parameters, swelling capacity, and hydrophilic properties, which were checked by the wetting angle measurement. On the other hand, higher oil content resulted in decreased water vapour permeability, which is essential in wound dressing. Furthermore, the prepared films were subjected to an acute toxicity test using a Microtox. Significantly, the film's increased cannabis oil content enhanced the antimicrobial effect against A. fischeri for films in direct contact with bacteria. More importantly, cell culture studies revealed that the obtained materials are biocompatible and, therefore, they might be potential candidates for application in wound dressing materials.

Bone Tissue Engineering in the Treatment of Bone Defects

Bones play an important role in maintaining exercise and protecting organs. Bone defect, as a common orthopedic disease in clinics, can cause tremendous damage with long treatment cycles. Therefore, the treatment of bone defect remains as one of the main challenges in clinical practice. Today, with increased incidence of bone disease in the aging population, demand for bone repair material is high. At present, the method of clinical treatment for bone defects including non-invasive therapy and invasive therapy. Surgical treatment is the most effective way to treat bone defects, such as using bone grafts, Masquelet technique, Ilizarov technique etc. In recent years, the rapid development of tissue engineering technology provides a new treatment strategy for bone repair. This review paper introduces the current situation and challenges of clinical treatment of bone defect repair in detail. The advantages and disadvantages of bone tissue engineering scaffolds are comprehensively discussed from the aspect of material, preparation technology, and function of bone tissue engineering scaffolds. This paper also summarizes the 3D printing technology based on computer technology, aiming at designing personalized artificial scaffolds that can accurately fit bone defects.

Surface Free Energy of Titanium Disks Enhances Osteoblast Activity by Affecting the Conformation of Adsorbed Fibronectin

This study evaluated the influence of surface free energy (SFE) of titanium disks on the adsorption and conformation of fibronectin (FN) and the biological behavior of osteoblasts cultured on the FN-treated modified surfaces. High [H]-SFE titanium disks were irradiated by a 30 W UV light, while low (L)-SFE titanium disks received no treatment. The surface characteristics of the titanium disks were examined using scanning electron microscope, optical surface profilometer, X-ray photoelectron spectroscopy, and contact angle measurements. Adsorbed FN on different groups was investigated using attenuated total reflection-Fourier transform infrared spectroscopy. MG-63 cells were cultured on FN-treated titanium disks to evaluate the in vitro bioactivity. The experiment showed H-SFE titanium disks adsorbed more FN and acquired more ß-turn content than L-SFE group. MG-63 cells cultured on FN-treated H-SFE titanium disks showed better osteogenic responses, including adhesion, proliferation, alkaline phosphatase activity and mineralization than that on FN-treated L-SFE titanium disks. Compared to L-SFE titanium disks, integrin-β1, integrin-α5 and Rac-1 mRNA levels were significantly higher in MG-63 cells on FN-treated H-SFE after 3 h of culture. These findings suggest that the higher SFE of H-SFE compared to L-SFE titanium disks induced changes in the conformation of adsorbed FN that enhanced the osteogenic activity of MG-63 cells.

Bioactive Coatings on Titanium: A Review on Hydroxylation, Self-Assembled Monolayers (SAMs) and Surface Modification Strategies

Titanium (Ti) and its alloys have been demonstrated over the last decades to play an important role as inert materials in the field of orthopedic and dental implants. Nevertheless, with the widespread use of Ti, implant-associated rejection issues have arisen. To overcome these problems, antibacterial properties, fast and adequate osseointegration and long-term stability are essential features. Indeed, surface modification is currently presented as a versatile strategy for developing Ti coatings with all these challenging requirements and achieve a successful performance of the implant. Numerous approaches have been investigated to obtain stable and well-organized Ti coatings that promote the tailoring of surface chemical functionalization regardless of the geometry and shape of the implant. However, among all the approaches available in the literature to functionalize the Ti surface, a promising strategy is the combination of surface pre-activation treatments typically followed by the development of intermediate anchoring layers (self-assembled monolayers, SAMs) that serve as the supporting linkage of a final active layer. Therefore, this paper aims to review the latest approaches in the biomedical area to obtain bioactive coatings onto Ti surfaces with a special focus on (i) the most employed methods for Ti surface hydroxylation, (ii) SAMs-mediated active coatings development, and (iii) the latest advances in active agent immobilization and polymeric coatings for controlled release on Ti surfaces.

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.

Enhanced melanoidin removal by amine-modified Phyllanthus emblica leaf powder

Melanoidins are classified as hazardous colouring and polluting biopolymers, which are generated in very large amounts in molasses-based distillery effluent. In this study, melanoidin was removed through adsorption using amine surface-modified Phyllanthus emblica leaf powder (PELP) as a low-cost natural adsorbent. The amine-modified adsorbents were prepared by forming self-assembled monolayers (SAMs). The pzc of melanoidin and anime-modified PELP were found to be 6.9 and 3.8, respectively. RSM-CCD was used to optimize the environmental conditions considering adsorbent doses (0.2-2 % w/v), pH (3-11) and temperature (25-55 °C). A complete decolourization of melanoidin (98.50 ± 1 %) was observed at the optimized conditions (44.0 °C, pH = 5.93 and dose = 1.34 % w/v) along with 93.4 ± 0.2 % of COD reduction. The surface modification enhanced the maximum adsorption capacity to 616.2 mg g^-1 i.e. 2.5 folds. The modified adsorbent also resulted in colour removal and COD reduction as 91 ± 3 and 84 ± 2 %, respectively from a real spentwash sample.

Highly stable collagen scaffolds crosslinked with an epoxidized natural polysaccharide for wound healing

As a biocompatible and bioactive natural tissue engineering collagen scaffold, porcine acellular dermal matrix (pADM) has limitations for the application in tissue regeneration due to its low strength and rapid biodegradation. Herein, to get a good wound dressing, the epoxy group was added to N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC) to synthesize the epoxidized N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (EHTCC), and the porcine acellular dermal matrix was modified with EHTCC at different dosage of 0, 4, 8, 12, 16 and 20%. The properties of the EHTCC-pADM were evaluated. The results indicated that the thermal stability and mechanical properties of EHTCC-pADM were remarkably improved, and the natural conformation of the matrix was maintained, which was beneficial to natural and excellent biological properties of the pADM. According to the test results of water contact angle, the hydrophilicity of the material was improved, which is conducive to cell adhesion, proliferation and growth. Cytotoxicity experiments showed that the introduction of EHTCC would not adversely affect the biocompatibility of the materials. In vivo experiments showed that EHTCC-pADM could promote wound healing. In conclusion, EHTCC-pADM is a potential collagen-based dressing for wound healing.

Fabrication of Submicro-Nano Structures on Polyetheretherketone Surface by Femtosecond Laser for Exciting Cellular Responses of MC3T3-E1 Cells/Gingival Epithelial Cells

Purpose

Polyetheretherketone (PEEK) exhibits high mechanical strengths and outstanding biocompatibility but biological inertness that does not excite the cell responses and stimulate bone formation. The objective of this study was to construct submicro-nano structures on PEEK by femtosecond laser (FSL) for exciting the responses of MC3T3-E1 cells and gingival epithelial (GE) cells, which induce regeneration of bone/gingival tissues for long-term stability of dental implants.

Materials and Methods

In this study, submicro-nano structures were created on PEEK surface by FSL with power of 80 mW (80FPK) and 160 mW (160FPK).

Results

Compared with PEEK, both 80FPK and 160FPK with submicro-nano structures exhibited elevated surface performances (hydrophilicity, surface energy, roughness and protein absorption). Furthermore, in comparison with 80FPK, 160FPK further enhanced the surface performances. In addition, compared with PEEK, both 80FPK and 160FPK significantly excited not only the responses (adhesion, proliferation, alkaline phosphatase [ALP] activity and osteogenic gene expression) of MC3T3-E1 cells but also responses (adhesion as well as proliferation) of GE cells of human in vitro. Moreover, in comparison with 80FPK, 160FPK further enhanced the responses of MC3T3-E1 cells/GE cells.

Conclusion

FSL created submicro-nano structures on PEEK with elevated surface performances, which played crucial roles in exciting the responses of MC3T3-E1 cells/GE cells. Consequently, 160FPK with elevated surface performances and outstanding cytocompatibility would have enormous potential as an implant for dental replacement.

Surface Characterization and Biocompatibility of Hydroxyapatite Coating on Anodized TiO2 Nanotubes via PVD Magnetron Sputtering

Hydroxyapatite (HA) coating has received significant attention in the scientific community for the development of implants, and HA coating on titanium oxide (TiO₂) nanotubes has shown potential benefits in the improvement of cell proliferation, adhesion, and differentiation. In this study, a HA coating on a TiO₂ nanotubular surface was developed to improve the biocompatibility of the titanium (Ti) surface via magnetron sputtering. Scanning electron microscopy (SEM), surface profilometry, and water contact goniometry revealed that HA-coated TiO₂ nanotubes influenced the surface roughness (R_a) and hydrophilicity. The XRD and FTIR peaks indicated the presence of crystalline phases of TiO₂ (anatase) and HA-coated TiO₂ nanotubes after annealing at 500 °C for 120 min. The HA-coated TiO₂ nanotubes showed significantly increased R_a and decreased water contact angle (θ) compared to the as-anodized TiO₂ nanotubular and bare CP-Ti surfaces. MTS assay using osteoblast-like cells confirmed that the HA-coated TiO₂ nanotubular surface provided an enhanced cell attachment and growth when compared to as-anodized TiO₂ nanotubular and pure CP-Ti surfaces.

Preparation and Characterization of Antibacterial Porcine Acellular Dermal Matrices with High Performance

Infection is a common complication in the process of wound management. An ideal wound dressing is supposed to reduce or even prevent the infection while promoting wound healing. A porcine acellular dermal matrix (pADM) has been already used as a wound dressing in clinic due to its capacity to accelerate wound healing. However, not only is pure pADM not antibacterial, its mechanical properties are poor. In this study, an antibacterial pADM with good performance was prepared by adding two natural products as modifiers, quercetin (QCT) and tea tree oil (TTO). The result of Fourier-transform infrared (FTIR) proved that the addition of modifiers did not break the natural triple-helical structure of collagen. Meanwhile, the results of differential scanning calorimetry (DSC), thermogravimetric analysis (TG), mechanic experiment, and enzymatic degradation demonstrated that pADM handled with QCT and TTO (termed QCT-TTO-pADM) had better thermal stability, mechanical strength, and resistance to enzymatic degradation than pADM. Meanwhile, QCT-TTO-pADM had excellent antibacterial activity and showed an antibacterial rate of over 80%. Furthermore, in the cytocompatibility analysis, QCT-TTO-pADM had no side effects on the adhesion, growth, and proliferation of fibroblasts. QCT-TTO-pADM could even accelerate wound healing more efficiently than pADM and glutaraldehyde-modified pADM (GA-pADM). In conclusion, QCT-TTO-pADM was a potential antibacterial wound dressing with good performance.

Shear-induced aggregation of amyloid β (1-40) in a parallel plate geometry

Protein aggregation is induced by various environmental or external factors and associated with various neurodegenerative diseases. Among various external factors, shear stress is inevitable for both in vivo and in vitro applications of proteins. In this study, Aβ (1-40) peptide, a derivative of the amyloid precursor protein, was subjected to constant (300, 500, 700 s^-1) and varying (ramp) shear in a parallel plate geometry to explore the implications of shear in terms of macro (viscosity) and micro (secondary structure, morphology) characteristics. Aβ (1-40) solution followed a shear thickening flow behaviour with performance index value 'n' of 2.12. The fibrillation process resulting from the shear force was evaluated in terms of dissipation energy, which was found to exceed the free energy of unfolding. This resulted in the formation of β-sheet rich structures, which were confirmed by CD and FTIR analyses and enhanced Th-T fluorescence. The apparent rate of aggregation (k) was found to increase with the shear rate, and inversely related to the solution viscosity. The maximum k value was 0.21 ± 0.3 min^-1 at 700 s^-1. The molecular weights of aggregates were determined using gel filtration, which were proportionally related to the solution viscosity. The average molecular weights were estimated to be 70, 62 and 52 KDa for samples sheared at 300, 500 and 700 s^-1, respectively. The present study has deciphered the interplay of viscosity, a fluid property, with the aggregation process and its corresponding change in the secondary structures of the peptide. These findings provide useful insights for understanding various proteopathies under shear force.Communicated by Ramaswamy H. Sarma.

Design of engineered surfaces for prospective detection of SARS-CoV-2 using quartz crystal microbalance-based techniques

INTRODUCTION

Rapid transmission of the severe acute respiratory syndrome coronavirus 2 has affected the whole world and forced it to a halt (lockdown). A fast and label-free detection method for the novel coronavirus needs to be developed along with the existing enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR)-based methods.

AREAS COVERED

In this report, biophysical aspects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein are outlined based on its recent reported electron microscopy structure. Protein binding sites are analyzed theoretically, which consisted of hydrophobic and positive charged amino acid residues. Different strategies to form mixed self-assembled monolayers (SAMs) of hydrophobic (CH₃) and negatively charged (COOH) groups are discussed to be used for the specific and strong interactions with spike protein. Bio-interfacial interactions between the spike protein and device (sensor) surface and its implications toward designing suitable engineered surfaces are summarized.

EXPERT OPINION

Implementation of the engineered surfaces in quartz crystal microbalance (QCM)-based detection techniques for the diagnosis of the novel coronavirus from oral swab samples is highlighted. The proposed strategy can be explored for the label-free and real-time detection with sensitivity up to ng level. These engineered surfaces can be reused after desorption.

Don't Forget Langmuir-Blodgett Films 2020: Interfacial Nanoarchitectonics with Molecules, Materials, and Living Objects

Designing interfacial structures with nanoscale (or molecular) components is one of the important tasks in the nanoarchitectonics concept. In particular, the Langmuir-Blodgett (LB) method can become a promising and powerful strategy in interfacial nanoarchitectonics. From this viewpoint, the status of LB films in 2020 will be discussed in this feature article. After one section on the basics of interfacial nanoarchitectonics with the LB technique, various recent research examples of LB films are introduced according to classifications of (i) growing research, (ii) emerging research, and (iii) future research. In recent LB research, various materials other than traditional lipids and typical amphiphiles can be used as film components of the LB techniques. Two-dimensional materials, supramolecular structures such as metal organic frameworks, and biomaterials such as DNA origami pieces are capable of working as functional components in the LB assemblies. Possible working areas of the LB methods would cover emerging demands, including energy, environmental, and biomedical applications with a wide range of functional materials. In addition, forefront research such as molecular manipulation and cell fate control is conducted in LB-related interfacial science. The LB technique is a traditional and well-develop methodology for molecular films with a ca. 100 year history. However, there is plenty of room at the interfaces, as shown in LB research examples described in this feature article. It is hoped that the continuous development of the science and technology of the LB method make this technique an unforgettable methodology.

Production of biosurfactant by Bacillus subtilis RSL-2 isolated from sludge and biosurfactant mediated degradation of oil

This study aims to unveil the effect of biosurfactant as stimulant in crude oil bioremediation. Isolated oil-degrading strain, B. subtilis RSL 2 was optimized for the maximum oil degradation and biosurfactant production using Response surface methodology. The produced biosurfactant was characterized and investigated for its effect on microbial oil degradation in two modes (a) sequential and (b) simultaneous. The strain produced 3.5 g/L of biosurfactant at pH 4.0, 25 °C, using 1 g/L crude oil as the only C-source in 7 days, which was characterized as lipopeptide with a critical micelle concentration (CMC) of 0.5 g/L. The biosurfactant improved surface wettability of a hydrophobic substrate i.e. increased surface energy from 30 ± 1 to 35 ± 1 mJ/m². Further, the simultaneous feed of biosurfactant at 0.5 CMC enhanced oil biodegradation (72%) and biosurfactant production (5.2 g/L) by about 1.6 times than the sequential mode due to improvement in mobilization of oil thus making it more bioavailable.

Effect of TiO2 addition on adhesion and biological behavior of BCP-TiO2 composite films deposited by magnetron sputtering

The present investigation focuses on the deposition of biphasic calcium phosphate (BCP) and titania (TiO₂) composite films on Ti-6Al-4V substrates using radio frequency (RF) magnetron sputtering. Three different compositions such as 100% BCP, 25% TiO₂-75% BCP and 50% TiO₂-50% BCP films were fabricated, and the physical, mechanical and biological behaviors of the films were analyzed. Post deposition, the films were annealed at 700 °C for 2 h to induce the crystallinity and to study its effect on different properties. The wettability was found to be 95°(±3°) for 100% BCP, 73°(±2°) for 25% TiO₂-75% BCP and 35°(±1°) for 50% TiO₂-50% BCP films, indicating improvement in wettability with an increase of TiO₂ weight percent in the composite films. The value of critical load (L_c2) for 100 BCP film improved from 8.7 N to 14.8 N (25 TiO₂-BCP) and >19 N (50 TiO₂-BCP film), indicating improvement in bonding strength with TiO₂ addition. The fetal bovine serum (FBS) adsorption decreased from 7.11 ± 0.25 to 4.42 ± 0.17 μg/cm² with TiO₂ weight percent from 0 to 50%. Cell adhesion and proliferation significantly improved in 100% BCP, 25% TiO₂-75% BCP and 50% TiO₂-50% BCP films as compared to uncoated Ti-6Al-4V. The maximum cell proliferation was found on the surface of 50% TiO₂-50% BCP film (210.1 ± 6.5%) after 6 days of incubation. However, after annealing all the films exhibited less cell adhesion and cytocompatibility presumably due to change in composition. Globular apatite structure was observed on all modified surfaces after 7 days immersion in simulated body fluid (SBF); however, the growth rate was higher for 50 TiO₂-BCP films. All these results revealed that the addition of TiO₂ in BCP film (without annealing) is advantageous for improving the bonding strength as well as the bioactivity of implants, which can be used for long-term dental and orthopedic applications.

Si substituted hydroxyapatite nanorods on Ti for percutaneous implants

An ideal intraosseous transcutaneous implant should form a tight seal with soft tissue, besides a requirement of osseointegration at the bone-fixed position. Si substituted hydroxyapatite (Si-HA) nanorods releasing Si ion and simulating nanotopography of natural tissue were designed on Ti to enhance fibroblast response in vitro and biosealing with soft tissue in vivo. Si-HA nanorods were fabricated by alkali-heat treatment followed with hydrothermal treatment. The hydrothermal formation mechanism of Si-HA nanorods was explored. The surface characteristic of Si-HA nanorods was compared with pure HA nanorods. Fibroblast behaviors in vitro and skin response in vivo on different surfaces were also evaluated. The obtained results show that the substitution of Si did not significantly alter the phase component, morphology, roughness and wettability of HA, but additional Si and more Ca were released from Si-HA into medium. Comparing to pure HA nanrods and Ti substrate, Si-HA nanrods enhanced cell behaviors including proliferation, fibrotic phenotype and collagen secretion in vitro, and reduced epithelial down growth in vivo. The enhanced cell response and biosealing should be due to the releasing of Ca, Si and nanotopography of Si-HA nanorods. Si-HA nanorods can be a potential coating to accelerate skin integration for percutaneous implants in clinic.

Silanized NaCa2HSi3O9 nanorods with a reduced pH increase on Ti for improving osteogenesis and angiogenesis in vitro

NaCa₂HSi₃O₉ nanorods with silane layers allow efficient Ca and Si release and controlled pH increase, and can enhance osteogenesis and angiogenesis on the Ti implant surface.

Prechondrogenic ATDC5 Cell Attachment and Differentiation on Graphene Foam; Modulation by Surface Functionalization with Fibronectin

Graphene foam holds promise for tissue engineering applications. In this study, graphene foam was used as a three-dimension scaffold to evaluate cell attachment, cell morphology, and molecular markers of early differentiation. The aim of this study was to determine if cell attachment and elaboration of an extracellular matrix would be modulated by functionalization of graphene foam with fibronectin, an extracellular matrix protein that cells adhere well to, prior to the establishment of three-dimensional cell culture. The molecular dynamic simulation demonstrated that the fibronectin-graphene interaction was stabilized predominantly through interaction between the graphene and arginine side chains of the protein. Quasi-static and dynamic mechanical testing indicated that fibronectin functionalization of graphene altered the mechanical properties of graphene foam. The elastic strength of the scaffold increased due to fibronectin, but the viscoelastic mechanical behavior remained unchanged. An additive effect was observed in the mechanical stiffness when the graphene foam was both coated with fibronectin and cultured with cells for 28 days. Cytoskeletal organization assessed by fluorescence microscopy demonstrated a fibronectin-dependent reorganization of the actin cytoskeleton and an increase in actin stress fibers. Gene expression assessed by quantitative real-time polymerase chain reaction of 9 genes encoding cell attachment proteins (Cd44, Ctnna1, Ctnnb1, Itga3, Itga5, Itgav, Itgb1, Ncam1, Sgce), 16 genes encoding extracellular matrix proteins (Col1a1, Col2a1, Col3a1, Col5a1, Col6a1, Ecm1, Emilin1, Fn1, Hapln1, Lamb3, Postn, Sparc, Spp1, Thbs1, Thbs2, Tnc), and 9 genes encoding modulators of remodeling (Adamts1, Adamts2, Ctgf, Mmp14, Mmp2, Tgfbi, Timp1, Timp2, Timp3) indicated that graphene foam provided a microenvironment conducive to expression of genes that are important in early chondrogenesis. Functionalization of graphene foam with fibronectin modified the cellular response to graphene foam, demonstrated by decreases in relative gene expression levels. These findings illustrate the combinatorial factors of microscale materials properties and nanoscale molecular features to consider in the design of three-dimensional graphene scaffolds for tissue engineering applications.

Thermal treatment to increase titanium wettability induces selective proteins adsorption from blood serum thus affecting osteoblasts adhesion

OBJECTIVES

To investigate how a thermal treatment to increase titanium wettability influences proteins adsorption from blood serum and osteoblasts responses.

METHODS

Titanium discs with machined or micro-rough profiles were thermally treated to obtain hydrophilic surfaces. The adsorption kinetics of two representative serum proteins were determined by Bradford assay, while the stable protein adsorption pattern from blood serum was investigated by SDS-PAGE and Western Blot analysis. Subsequently, MC3T3-E1 cells were cultured on titanium for 24h and assayed for adhesion and morphology.

RESULTS

Thermally-induced hydrophilicity dramatically improved the capacity of titanium to selectively adsorb fibronectin and fibrinogen from blood serum, without evident influence on other representative serum proteins. The selective adsorption of fibronectin was linked to the improved capacity of MC3T3-E1 cells to adhere and spread on hydrophilic surfaces.

SIGNIFICANCE

We identified a potential method to improve selective protein adsorption on titanium by enhancing implant surface wettability through a thermal treatment. Selective fibronectin adsorption was further indicated as the responsible for improved osteoblasts adhesion. Targeting specific cell response by selective protein adsorption appears to be crucial to conceive even more performant therapies.

Influence of Short Cationic Lipopeptides with Fatty Acids of Different Chain Lengths on Bacterial Biofilms Formed on Polystyrene and Hydrogel Surfaces

Nowadays, biomaterials are applied in many different branches of medicine. They significantly improve the patients' comfort and quality of life, but also constitute a significant risk factor for biofilm-associated infections. Currently, intensive research on the development of novel materials resistant to microbial colonization as well as new compounds that are active against biofilms is being carried out. Within this research, antimicrobial peptides (AMPs) and their analogues are being intensively investigated due to their promising antimicrobial activities. The main goal of this study was to synthesize and evaluate the antimicrobial efficacy of short cationic lipopeptides that were designed to imitate the features of AMPs responsible for antimicrobial activities: positive net charge and amphipacity. The positive charge of the molecules results from the presence of basic amino acid residues: arginine and lysine. Amphipacity is provided by the introduction of decanoic, dodecanoic, tetradecanoic, and hexadecanoic acid chains to the molecules. Lipopeptides (C16-KR-NH2, C16-KKK-NH2, C16-KKC-NH2, C16-KGK-NH2, C14-KR-NH2, C14-KKC-NH2, C12-KR-NH2, C12-KKC-NH2, and (C10)2-KKKK-NH2) were synthesized using a novel solid-phase temperature-assisted methodology. The minimum inhibitory concentrations (MICs), minimum biofilm eradication concentrations (MBECs), and minimum biofilm formation inhibitory concentrations (MBFICs) were determined for the following bacterial strains: Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis ATCC 14990, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 9027, and Proteus mirabilis PCM 543. The biofilms were cultured on two types of surfaces: polystyrene plates (PS) and contact lenses (CL). The lipopeptides exhibited the ability to inhibit the growth of bacteria in a liquid medium as well as on the PS and CL. The compounds also eliminated the bacterial biofilm from the surface of both materials. In general, the activity against gram-positive bacteria was stronger in comparison to that against gram-negative strains. There were certain discrepancies between the activity of compounds against the biofilm cultured on PS and CL. This was especially noticeable for staphylococci-the lipopeptides presented much higher activity against biofilm formed on the PS surface. It is worth noting that the obtained MBEC values for lipopeptides were usually only a few times higher than the MICs. The results of the performed experiments suggest that further studies on lipopeptides and their potential application in the treatment and prophylaxis of biofilm-associated infections should be conducted.

Femtosecond Laser Nano/Micro Textured Ti6Al4V Surfaces-Effect on Wetting and MG-63 Cell Adhesion

Nano- and microstructured titanium surfaces have recently attracted attention in the field of regenerative medicine because of the influence which surface characteristics such as roughness and wettability can have on cellular processes. This study focuses on the correlation of surface properties (wettability and nano/micro texture) of laser-structured Ti6Al4V samples with pronounced cell adhesion. Samples were structured with multiple laser parameters in order to create a range of surface properties. Surface characterization was performed by contact angle measurements 1 and 7 days after laser processing. The arithmetic mean roughness of the material surface in an area (Sa) was determined by means of confocal laser scanning microscopy (CLSM). Immediately after wettability tests of the laser-structured surfaces, in vitro experiments with human MG-63 osteoblasts were carried out. For this purpose, the cell morphology and actin cytoskeleton organization were analyzed using CLSM and scanning electron microscopy. On rough microstructures with deep cavities, the cell growth and spreading were inhibited. An improved cellular adhesion and growth on nanostructured and sinusoidal microstructured surfaces could be demonstrated, regardless of hydrophilicity of the surfaces.

Insights into the Osteogenic Differentiation of Mesenchymal Stem Cells on Crystalline and Vitreous Silica

Cell responses to oxide biomaterials depend on the protein adsorption behavior of the biomaterial surface. Thus, the inherent properties of oxide biomaterial surfaces play a key role in this process. However, commonly used biomaterials, such as calcium phosphate and titanium dioxide, have surfaces with strong mineralization, which may interfere with the ability to clarify the key aspects of the oxide biomaterial regarding protein adsorption and cellular processes. Here, nonmineralized crystalline and vitreous silica were selected as model oxide biomaterials to explore the inherent properties of these materials on the absorption behavior of the functional protein fibronectin (Fn) and on the osteogenic differentiation of mesenchymal stem cells (MSCs). We demonstrated that due to the smaller O_1s binding energy, the weaker polarization of oxygen atoms in vitreous silica produced a greater amount of acidic hydroxyls after hydration compared to crystalline silica. These distinct features significantly upregulated the exposure of arginylglycylaspartic acid (RGD) and synergy sites (PHSRN) of Fn and eventually enhanced the osteogenic differentiation of MSCs on vitreous silica surfaces through activation of the integrin-linked kinase (ILK) signaling pathway. Our results highlight the key role of inherent oxide biomaterial crystallinity in protein adsorption and cell behavior.

Local Surface Electric Field’s Effect on Adsorbed Proteins’ Orientation

Hydrogenated nanocrystalline silicon, while being non-charged and non-polar, could be an ideal candidate for the non-covalent and orientation-controlled immobilization of biomolecules thanks to local electric fields around nanocrystals. To that effect, the adsorption of bovine serum albumin on substrates with different densities of nanocrystals, revealed by Raman spectroscopy and X-ray diffraction, was studied using infrared spectroscopy and atomic force microscopy. It was found that the protein–surface interactions followed different mechanisms depending on the nanostructure at the surface: hydrophobic on the non-crystalline part of the surface and electrostatic around the crystalline part. These electrostatic interactions were driven by the electric fields that arose at the junction between crystalline and amorphous structures. These electric fields were found to be strong enough to interact with the amide dipoles, thereby reorienting the adsorbed protein molecules on this part of the surface. Nevertheless, the adsorbed proteins were found to be denatured, which was due to the surface chemistry, and not affected by the nanostructure.

Nanolamellar Tantalum Interfaces in the Osteoblast Adhesion

The design of topographically patterned surfaces is considered to be a preferable approach for influencing cellular behavior in a controllable manner, in particular to improve the osteogenic ability of bone regeneration. In this study, we fabricated nanolamellar tantalum (Ta) surfaces with lamellar wall thicknesses of 40 and 70 nm. The cells attached to nanolamellar Ta surfaces exhibited higher protein adsorption and expression of β1 integrin, as compared to the nonstructured bulk Ta, which facilitated the initial cell attachment and spreading. We thus, as expected, observed significantly enhanced osteoblast adhesion, growth, and alkaline phosphatase activity on nanolamellar Ta surfaces. However, the beneficial effects of nanolamellar structures on osteogenesis became weaker as the lamellar wall thickness increased. The interaction between cells and Ta surfaces was examined through adhesion forces using atomic force microscopy. Our findings indicated that the Ta surface with a lamellar wall thickness of 40 nm exhibited the strongest stimulatory effect. The observed strongest adhesion force between the cell-attached tip and the Ta surface with a 40 nm thick lamellar wall encouraged the much stronger binding of cells with the surface and thus well-attached, -stretched, and -grown cells. We attributed this to the increase in the available contact area of cells with the thinner nanolamellar Ta surface. The increased contact area allowed the enhancement of the cell surface interaction strength and, thus, improved osteoblast adhesion. This study suggests that the thin nanolamellar topography shows immense potential in improving the clinical performance of dental and orthopedic implants.

Neuronal SNARE complex: A protein folding system with intricate protein-protein interactions, and its common neuropathological hallmark, SNAP25

SNARE (Soluble NSF(N-ethylmaleimide-sensitive factor) Attachment Receptor) complex is a trimeric supramolecular organization of SNAP25, syntaxin, and VAMP which mediates fusion of synaptic vesicles with the presynaptic plasma membrane. The functioning of this entire protein assembly is dependent on its tetrahelical coiled coil structure alongside its interaction with a large spectrum of regulatory proteins like synaptotagmin, complexin, intersectin, etc. Defects arising in SNARE complex assembly due to mutations or faulty post-translational modifications are associated to severe synaptopathies like Schizophrenia and also proteopathies like Alzheimer's disease. The review primarily focuses on SNAP25, which is the prime contributor in the complex assembly. It is conceptualized that the network of protein interactions of this helical protein assists as a chaperoning system for attaining functional structure. Additionally, the innate disordered nature of SNAP25 and its amyloidogenic propensities have been highlighted employing computational methods. The intrinsic nature of SNAP25 is anticipated to form higher-order aggregates due to its cysteine rich domain, which is also a target for several post-translational modifications. Furthermore, the aberrations in the structure and expression profile of the protein display common patterns in the pathogenesis of a diverse synaptopathies and proteopathies. This work of SNARE literature aims to provide a new comprehensive outlook and research directions towards SNARE complex and presents SNAP25 as a common neuropathological hallmark which can be a diagnostic or therapeutic target.

Tackling the Concept of Symbiotic Implantable Medical Devices with Nanobiotechnologies

This review takes an approach to implanted medical devices that considers whether the intention of the implanted device is to have any communication of energy or materials with the body. The first part describes some specific examples of three different classes of implants, analyzed with regards to the type of signal sent to cells. Through several examples, the authors describe that a one way signaling to the body leads to encapsulation or degradation. In most cases, those phenomena do not lead to major problems. However, encapsulation or degradation are critical for new kinds of medical devices capable of duplex communication, which are defined in this review as symbiotic devices. The concept the authors propose is that implanted medical devices that need to be symbiotic with the body also need to be designed with an intended duplex communication of energy and materials with the body. This extends the definition of a biocompatible system to one that requires stable exchange of materials between the implanted device and the body. Having this novel concept in mind will guide research in a new field between medical implant and regenerative medicine to create actual symbiotic devices.