Nanofiber Coatings Research Articles

The dual-effects of PLGA@MT electrospun nanofiber coatings on promoting osteogenesis at the titanium-bone interface under diabetic conditions.

The high failure risk of endosseous titanium implants under diabetes conditions appeals to strengthen the osteointegration on the titanium-bone (Ti-B) interface. Melatonin (MT) is a neurohormone involved in bone homeostasis, which can promote osteogenesis and inhibit ROS overproduction through multiple pathways, but its effects on the Ti-B interface in diabetes remain elusive. The biodegradable poly(lactic-co-glycolic acid) (PLGA) has excellent controlled and sustained release properties, low cytotoxicity, and biocompatibility. Our study fabricated a nanofiber in which MT was encapsulated in PLGA to generate a nanofiber coating on a polydopamine (PDA)-modified titanium surface using electrospinning technology. The surface characteristic showed that MT was fully encapsulated in the PLGA carrier, and PLGA@MT was strongly coupled to the titanium matrix. Furthermore, the PLGA@MT-Ti nanofiber could release MT for at least 30 days. In vitro cellular tests demonstrated that PLGA@MT-Ti directly stimulates osteogenesis on the Ti-B interface by activating the BMP-4/WNT pathway in a dose-dependent manner. The effect of suppressing diabetes-induced ROS overproduction and promoting cell proliferation was not proportional to the content of MT. In vivo experiments revealed that PLGA@MT-Ti screws promoted the bone formation and osteointegration in type 1 diabetes mellitus (T1DM) mice with tibial bone defects. Our findings demonstrate that PLGA@MT-Ti exerted dual effects through activating the BMP-4/WNT pathway and attenuating ROS overproduction to promote osteogenesis and osteointegration at the Ti-B interface, providing a novel strategy to fabricate biomaterial modification and biofunctionalization under diabetic conditions.

Electrospun Biodegradable Nanofibers Coated Homogenously by Cu Magnetron Sputtering Exhibit Fast Ion Release. Computational and Experimental Study.

Copper-coated nanofibrous materials are desirable for catalysis, electrochemistry, sensing, and biomedical use. The preparation of copper or copper-coated nanofibers can be pretty challenging, requiring many chemical steps that we eliminated in our robust approach, where for the first time, Cu was deposited by magnetron sputtering onto temperature-sensitive polymer nanofibers. For the first time, the large-scale modeling of PCL films irradiation by molecular dynamics simulation was performed and allowed to predict the ions penetration depth and tune the deposition conditions. The Cu-coated polycaprolactone (PCL) nanofibers were thoroughly characterized and tested as antibacterial agents for various Gram-positive and Gram-negative bacteria. Fast release of Cu2+ ions (concentration up to 3.4 µg/mL) led to significant suppression of E. coli and S. aureus colonies but was insufficient against S. typhimurium and Ps. aeruginosa. The effect of Cu layer oxidation upon contact with liquid media was investigated by X-ray photoelectron spectroscopy revealing that, after two hours, 55% of Cu atoms are in form of CuO or Cu(OH)2. The Cu-coated nanofibers will be great candidates for wound dressings thanks to an interesting synergistic effect: on the one hand, the rapid release of copper ions kills bacteria, while on the other hand, it stimulates the regeneration with the activation of immune cells. Indeed, copper ions are necessary for the bacteriostatic action of cells of the immune system. The reactive CO2/C2H4 plasma polymers deposited onto PCL-Cu nanofibers can be applied to grafting of viable proteins, peptides, or drugs, and it further explores the versatility of developed nanofibers for biomedical applications use.

Conductive epoxy/carbon nanofiber coatings for scale control

Calcium carbonate (CaCO3) is one of the most widespread scaling minerals and has been a long-standing problem within many industrial sectors. Scaling of calcium carbonate on conductive surfaces can be prevented electrochemically by anodic polarization. Anodic polarization, however, cannot be applied directly to metal surfaces like e.g., steel that will suffer from corrosion when polarized anodically in an aqueous environment. Thus, in this paper it is proposed to apply a conductive coating to a metal surface to allow anodic polarization and inhibit surface scaling, without corrosion of the underlying metal surface taking place. To this end an epoxy/carbon nanofiber conductive coating was developed and deposited at steel surfaces. The coating showed good adhesion to the surface and the bulk and surface resistivities were in the order of 52.80 kΩcm and 31.87 kΩ/cm2, respectively. The anti-scaling performance of the coating without- and under anodic polarization was tested upon exposure to 1.5 wt% CaCl2 solution being in contact with CO2. The coating has been tested at several different potentials to find optimal conditions for scale inhibition. Potentials above +3 VOCP caused a degradation of the coating due to oxygen evolution at the anode, as well as evolution of chlorine gas. At +1.5 and + 2 VOCP the coating remained intact and the precipitation of CaCO3 was limited. On the other hand, cathodic polarization of the coating surface enhanced scaling and no coating degradation was observed at cathodic polarization even at potentials as high as −5 VOCP. The coating has thus proven a good solution to control surface scale deposition. Both anodic scale inhibition and cathodic scale acceleration have been achieved at the coating surfaces.

Effect of solution blown nanofibers on Mode‐I fracture toughness and dynamic mechanical properties of carbon fiber‐reinforced composites

AbstractIn this study, solution‐blown nanofibers were coated on carbon fiber (CF) fabrics to improve Mode‐I fracture toughness and dynamic mechanical properties of the composite laminates. Nanofiber coatings of various basis weights were directly spun over CF fabrics, which were then formed into composite laminates via vacuum‐assisted resin transfer molding. A double cantilever beam test was conducted to analyze the Mode‐I fracture toughness of CF‐reinforced epoxy composites. The results showed that solution‐blown nanofiber coatings stabilized the crack propagation and increased the delamination strength hence increased the Mode‐I fracture toughness by nearly 48% for the addition of 1 g/m2 nanofibrous web. Dynamic mechanical analysis was performed to investigate the effect of nanofibers on the stiffness of materials and the homogeneity of samples. Storage modulus, loss modulus, and damping factor were calculated, and corresponding Cole‐Cole plots were drawn. DMA results showed that the stiffness of the composite sample increased up to 17% even after a minor amount (1 g/m2) of nanofiber coating.

Enhanced Optical Sensitivity of Polyvinyl Alcohol–Reduced Graphene Oxide Electrospun Nanofiber Coated Etched Fiber Bragg Grating Sensor for Detection of Myoglobin a Cardiac Biomarker

Etched fiber Bragg grating (eFBG) sensors have shown to be highly sensitive with the capability of giving accurate real‐time response to a variety of measurands such as pressure, gas, biomolecules, to name a few. These sensors have not shown their mettle as competitive products mainly due to nonreproducibility in results and inefficiency in upscaling for large‐scale production; the main reason being nonuniform and complicated coating procedures. Herein, the enhancement in refractive index (RI) sensitivity (≈4 times) obtained with electrospinning of polyvinyl alcohol–reduced graphene oxide (PVA–rGO) nanofibers onto eFBG sensor using a customized target and a unique sandwich arrangement is demonstrated. The enhancement in RI sensitivity has led to a lower detection limit and increased sensitivity and linear range for a case study using myoglobin (Mb), an early‐stage cardiac biomarker with high reproducible results (standard error ≤±2.3%). rGO embedded PVA nanofiber electrospun onto an eFBG sensor (PVA–rGO sensor) is the first of its kind and has significant importance in developing cost‐effective, label‐free, multianalyte, portable, real‐time, point‐of‐care (POC) kits at ambient conditions.

Graphene/chitosan/Ag+- doped hydroxyapatite triple composite fiber coatings on new generation hybrid titanium composite by electrospinning

In this work, The hybrid hydroxyapatite (HaP), chitosan (CH) and graphene nanosheets (GNS) mixtures were applied by electrospinning on the surface of GNS and Si3N4 (SN) binary powder reinforced hybrid titanium (Ti) metal composites surface to improve composite biosurface functionallity. The surfaces of coated materials were characterized and antibacterial tests were carried on for their suitability in the industry by performing artificial body fluid tests. The hybrid nano fiber coatings formed a homogeneous structure on the composite. According to bioactivity tests and microstructure analysis, it was seen that HaP, which has the best results in the change of pH (pH= 11.80) values. The lowest mass change (0.0005 g) was observed on the 10th day of pure titanium. The highest mass change (0.0210 g) was obtained as on the HaP coated hybrid titanium composite. According to the antibacterial test result the hybrid nanofiber containing silver (Ag+) doped HaP on Ti composites showed the best antibacterial property aganist the E.coli. The fabricated electrospin coated hybrid composites can be a potantial candidate for dental, orthopedic implant applications and tissue engineering.

Cellulose Nanofiber Coatings on Cu Electrodes for Cohesive Protection against Water-Induced Short-Circuit Failures

Water is detrimental to electronic devices because it easily causes short circuits. The use of sealing to prevent water permeation is considered as the current conventional solution; however, the trend for developing flexible and stretchable electronic circuits has placed severe demands on waterproof technologies. This report describes a coating that protects circuits and prevents between-wire short circuits, even if the waterproof seals are damaged and the circuit becomes wet. We show that when Cu electrodes are coated with cellulose nanofibers (carboxylate content of 1.8 mmol/g), short circuits between the electrodes do not occur, even if the circuit is submerged in water for 24 h. The cellulose nanofibers accumulate at the anode because of electrophoresis, thereby forming a cohesive cellulose nanofiber layer that prevents short circuits between electrodes. Even if the cellulose nanofiber coating cracks because of external factors, the electrophoretic effect repairs the coating. This failure-containment mechanism is expected to be used in combination with existing waterproofing technology to dramatically improve the reliability of next-generation electronic devices under extreme operating conditions.

Low-cost disposable Poly(ethyleneimine)-Functionalized Carbon Nanofibers Coated Cellulose Paper as efficient solid phase extraction sorbent material for the extraction of Parahydroxybenzoates from environmental waters

Parahydroxybenzoates (parabens) are considered as emerging environmental contaminants because of their extensive usage in our daily life products, causing parabens contamination into environmental water systems and lead to toxic effects on environmental health. This study describes a greener extraction method using a new cationic polymer poly (ethyleneimine) functionalized acid-treated carbon nanofibers (PEI-CNFs) coated cellulose paper (CP) as solid-phase extraction (SPE) sorbent material for the extraction of parabens from environmental water samples. The fabrication of PEI-CNFs modified CP was confirmed using field-emission scanning electron microscope, transmission electron microscopy, and fourier-transformer infrared spectroscopy techniques. Various factors affecting the adsorption and desorption of parabens on PEI-CNFs@CP and its extraction efficiencies were studied using HPLC-UV analysis. Under the optimal experimental conditions, maximum extraction efficiencies were achieved for four target parabens, and PEI-CNFs@CP/HPLC-UV method exhibited excellent linearities ranged from 0.5–50 ng mL−1 with regression coefficient values were between 0.9952–0.9970. The presented method showed good sensitivity with quantification limits between 0.5–0.75 ng mL−1 and detection limits between 0.1–0.25 ng mL−1. The developed technique was applied for the real sample analysis (river, lake, domestic sewage water, and drinking tap water). The spiked recovery revealed good recoveries between 86.8–116.0% with RSD less than 8.8% for all the water samples. These results proved that it a simple, fast, efficient, low-cost, and eco-friendly method for the extraction and determination of parabens in environmental water samples and can be applied as a routine analytical tool in environmental monitoring and quality control laboratories.

Fabrication of Bioabsorbable Polylactic-Co-Glycolic Acid/Polycaprolactone Nanofiber Coated Stent and Investigation of Biodegradability in Porcine Animal Model.

Stent-mediated therapy is minimally invasive and fairly effective for the specific tissue and organs with tubal structures such as the esophagus, intestine, and blood vessels. Cerebral arteries are one of the most critical tubal structures to maintain the physiological function and the life of the human. Since the retrieval of the implanted vascular stent is difficult and risky, the one-step stent therapy is imperative. However, the placement of a current pipe-typed stent can also limit the nutritional supply to the vascular wall. Also, the non-degradable polymeric layer is possibly sensitized to the recipient as a foreign body after prolonged period after implantation. Herein, we developed PLGA/PCL nanofiber-coated stent for blocking the flow towards the aneurysm cavity as well as allowing nutritional support to the vessel with the biodegradability. The PLGA/PCL nanofiber-coated stent (NCS) was fabricated via electrospinning composite nanofibers onto a self-expandable mater metal stent. The as-fabricated NCS was physicochemically characterized using FT-IR, FE-SEM, and UTM, and experimented in vivo as implanted in porcine models and radiologically and histologically analyzed. The NCS demonstrated improved physicochemical properties for intracranial aneurysmal treatment including enhanced mechanical properties. The bioabsorbability of NCS was confirmed in the animal model.

Thiol-norbornene reactions to improve natural rubber dispersion in cellulose nanofiber coatings

Cellulose nanofibrils (CNF) coatings are excellent grease barriers for biodegradable packaging. However, barrier properties are moisture sensitive, so hydrophobic components such as latexes or polymers are needed to impart moisture resistance, but incompatibility leads to poor dispersion. In this work, CNF modified with norbornenes was reacted with natural rubber (NR) latex in water to improve dispersion, coating formation, and coating moisture resistance by creating hybrid particles. Mixtures and reacted samples were coated through filtration onto paper. The hybrid particles improved NR retention and drainage rate as compared to the CNF/latex mixture. Hybrid particle coatings showed more uniform NR dispersion as compared to the mixtures, which formed NR and CNF layers. NR addition to coatings increased the water contact angle, reduced water absorption, and decreased the water vapor transmission rate. All coatings passed a 12-kit grease test before folding and the mixtures formed a crack-resistant CNF layer on the surface.

Dual directions to address the problem of aseptic loosening via electrospun PLGA @ aspirin nanofiber coatings on titanium

Peri-implant aseptic inflammation and osteolysis can cause aseptic loosening, leading to the failure of implants. Therefore, aseptic loosening of orthopedic implants remains an imminent problem for the development of durable and effective implants. In this work, a common anti-inflammatory drug (aspirin, ASA) was loaded in poly(lactic-co-glycolic acid) (PLGA) to construct nanofiber coatings on titanium (Ti) via electrospinning. The adhesion of the nanofiber coatings to Ti was ensured by polydopamine (PDA) modification. A stable and sustainable release of aspirin from the nanofiber coatings could last up to 60 days. Such electrospun PLGA@ASA nanofiber coatings could promote proliferation and osteogenic differentiation of bone mesenchymal stem cells (BMSCs) as well as inhibit M1 polarization and RANKL-induced osteoclast differentiation of macrophages in vitro. These results indicated that this facile formulation of the PLGA@ASA nanofiber coatings for long-term drug release could be expected to address the problem of aseptic loosening effectively in dual directions of both anti-inflammation and improving osseointegration simultaneously. Notably, the in vivo experiments demonstrated that PLGA@ASA nanofiber coatings did promote osseointegration ability of Ti implants significantly, even in challenging condition with wear particles, and also effectively inhibited Ti particle induced osteolysis around the implants. This work indicates a promising way for the development of durable and effective implants by using PLGA@ASA-PDA-Ti to address the problem of aseptic loosening in dual directions.

Bile acid bearing poly (vinyl chloride) nanofibers by combination of CuAAC click chemistry and electrospinning process

This study aims to deposit most common bile acids such as lithocholic acid (LCA) and chenodeoxycholic acid (CDCA) bearing poly (vinyl chloride) nanofiber (PVC-LCA and PVC-CDCA) coatings on glass slides surface using a combination method by employing copper (I)-catalyzed azide-alkyne cycloaddition ‘click’ reaction (CuAAC), followed by electrospinning process. The resulted nanofibers and their intermediates are characterized by spectroscopic (FT-IR- 1H-NMR), thermal (TGA and DSC), wettability (WCA) and morphological (SEM) analyses. Many characterizations reveal that the bile acid functionalized PVC-LCA and PVC-CDCA are successfully achieved by CuAAC between azido-functional PVC (PVC-N3) and alkyne end-functional LCA and CDCA (LCA-Alkyne and CDCA-Alkyne) and their nanofibers obtained by electrospinning show efficiently improved thermal behavior, hydrophilicity and morphological features compared to pristine PVC or their granule analogues. Furthermore, the SEM images indicate that the formation of nanoscale, uniform, cylindrical and smooth fibers without free beads. The changeable properties achieved are attributed to the presence of rigid steroid skeleton, triazole rings and free −OH groups on the final polymers. Hence, it is clear that this facile combination procedure is encouraging for scientists working on potential biomedical PVC applications.

Conformable self-assembling amyloid protein coatings with genetically programmable functionality.

Functional coating materials have found broad technological applications in diverse fields. Despite recent advances, few coating materials simultaneously achieve robustness and substrate independence while still retaining the capacity for genetically encodable functionalities. Here, we report Escherichia coli biofilm-inspired protein nanofiber coatings that simultaneously exhibit substrate independence, resistance to organic solvents, and programmable functionalities. The intrinsic surface adherence of CsgA amyloid proteins, along with a benign solution-based fabrication approach, facilitates forming nanofiber coatings on virtually any surface with varied compositions, sizes, shapes, and structures. In addition, the typical amyloid structures endow the nanofiber coatings with outstanding robustness. On the basis of their genetically engineerable functionality, our nanofiber coatings can also seamlessly participate in functionalization processes, including gold enhancement, diverse protein conjugations, and DNA binding, thus enabling a variety of proof-of-concept applications, including electronic devices, enzyme immobilization, and microfluidic bacterial sensors. We envision that our coatings can drive advances in electronics, biocatalysis, particle engineering, and biomedicine.

Optimization the Process of Chemically Modified Carbon Nanofiber Coated Monolith via Response Surface Methodology for CO2 Capture.

In the present study, a sequence of experiments was performed to assess the influence of the key process parameters on the formation of a carbon nanofiber-coated monolith (CNFCM), using a four-level factorial design in response surface methodology (RSM). The effect of reaction temperature, hydrocarbon flow rate, catalyst and catalyst promoter were examined using RSM to enhance the formation yield of CNFs on a monolith substrate. To calculate carbon yield, a quadratic polynomial model was modified through multiple regression analysis and the best possible reaction conditions were found as follows: a reaction temperature of 800 °C, furfuryl alcohol flow of 0.08525 mL/min, ferrocene catalyst concentration of 2.21 g. According to the characterization study, the synthesized CNFs showed a high graphitization which were uniformly distributed on a monolith substrate. Besides this, the feasibility of carbon dioxide (CO2) adsorption from the gaseous mixture (N2/CO2) under a range of experimental conditions was investigated at monolithic column. To get the most out of the CO2 capture, an as-prepared sample was post-modified using ammonia. Furthermore, a deactivation model (DM) was introduced for the purpose of studying the breakthrough curves. The CO2 adsorption onto CNFCM was experimentally examined under following operating conditions: a temperature of 30–50 °C, pressure of 1–2 bar, flow rate of 50–90 mL/min, and CO2 feed amount of 10–40 vol.%. A lower adsorption capacity and shorter breakthrough time were detected by escalating the temperature. On the other hand, the capacity for CO2 adsorption increased by raising the CO2 feed amount, feed flow rate, and operating pressure. The comparative evaluation of CO2 uptake over unmodified and modified CNFCM adsorbents confirmed that the introduced modification procedure caused a substantial improvement in CO2 adsorption.

Three-Dimensional Coating of SF/PLGA Coaxial Nanofiber Membranes on Surfaces of Calcium Phosphate Cement for Enhanced Bone Regeneration.

Calcium phosphate cements (CPCs) have been widely used for the study of bone regeneration because of their excellent physical and chemical properties, but poor biocompatibility and lack of osteoinductivity limit potential clinical applications. To overcome these limitations, and based on our previous research, CPC scaffolds were prepared with CPC as the principal material and polyethylene glycol (PEG) as a porogen to introduce interconnected macropores. Using a bespoke electrospinning auxiliary receiver, silk fibroin (SF)/poly(lactide-co-glycolide) (PLGA) coaxial nanofibers containing dexamethasone (DXM) and recombinant human bone morphogenetic protein-2 (rhBMP2) were fabricated which were coated on the surface of the CPC. By comparing the surface morphology by SEM, hydrophilicity, results of FTIR spectroscopy, and mechanical properties of the composite materials fabricated using different electrospinning times (20, 40, 60 min), the CPC surface constructed by electrospinning for 40 min was found to exhibit the most appropriate physical and chemical properties. Therefore, composite materials were built for further study by electrospinning for 40 min. The osteogenic capacity of the SF/PLGA/CPC, SF-DXM/PLGA/CPC, and SF-DXM/PLGA-rhBMP2/CPC scaffolds was evaluated by in vitro cell culture with rat bone marrow mesenchymal stem cells (BMSCs) and using a rat cranial defect repair model. ALP activity, calcium deposition levels, upregulation of osteogenic genes, and bone regeneration in skull defects in rats with SF-DXM/PLGA-rhBMP2/CPC implants were significantly higher than in rats implanted with the other scaffolds. These results suggest that drug-loaded coaxial nanofiber coatings prepared on a CPC surface can continuously and effectively release bioactive drugs and further stimulate osteogenesis. Therefore, the SF-DXM/PLGA-rhBMP2/CPC scaffolds prepared in this study demonstrated the most significant potential for the treatment of bone defects.

Coating biodegradable magnesium alloys with electrospun poly-L-lactic acid-åkermanite-doxycycline nanofibers for enhanced biocompatibility, antibacterial activity, and corrosion resistance

Magnesium alloys are attracting increasing attention for orthopedic applications on account of their superior biocompatibility and biodegradability. However, such applications have been limited by their high degradation rate and inadequate antibacterial performance. The present study illustrates the use of a poly-L-lactic acid (PLLA)-åkermanite (AKT)-doxycycline (DOXY) nanofiber coating, created using the electrospinning method, to enhance the corrosion resistance, antibacterial performance, and cytocompatibility of Mg alloys. The experimental results show the PLLA-based nanofiber coatings are smooth and uniform with fiber diameters ranging from 300 to 350 nm. PLLA nanofibers containing AKT have a higher bonding strength (11.8 MPa) than PLLA nanofibers, owing to the significant effect of AKT on the PLLA structure. An in vitro drug release profile of PLLA-AKT nanofibers containing DOXY shows that the nanofibers allow rapid release of drug in the initial stage to provide antibacterial effects as well as sustained release over the long term to prevent infection. The implants coated with PLLA-AKT nanofibers containing DOXY have excellent antibacterial performance against Gram-positive (Staphylococcus aureus, ATCC 12600) and Gram-negative (Escherichia coli, ATCC 9637) bacteria; those coated with PLLA and PLLA-AKT without DOXY have poor antibacterial performance. Cytotoxicity tests show that PLLA and PLLA-AKT nanofiber coatings considerably enhance the cytocompatibility of Mg alloys, while incorporation of a high concentration of DOXY (10% wt.) into the PLLA-AKT coating has adverse effects on cytocompatibility. Thus, PLLA-AKT nanofiber coatings containing low concentrations of DOXY can be employed to control the degradation rate and enhance the antibacterial performance and biocompatibility of Mg alloys as applied to bone infection treatments. The results of this study represent essential information to direct the development of future orthopedic applications.

In vitro and In vivo Assessment of an Electrospun Nanofiber Coated Decellularized Bovine Pericardium as a Regenerative Valve Substitute vs. Glutaraldehyde Fixed Pericardium

Objective: Decellularized bovine pericardium (DBP) fixed with glutaraldehyde (GA) is the current standard of choice, for valve tissue reconstructions in children. DBP-GA is inert due to the cytotox...

Influence of Pressure to Morphology of TiO<sub>2</sub> Nanofibers Prepared by Microwave-Assisted Synthesis Method

Microwave-assisted hydrothermal synthesis of TiO2 nanofibers under various temperature and pressure conditions were done in this research. High quality TiO2 nanofiber coatings where obtained when temperature was in range 240 – 245 °C and pressure was 27.3 – 29.1 bar. Obtained TiO2 nanofiber coatings are with a specific surface area of ​​151.5 to 158.9 m2· g-1 before calcination. Comparing with nanopowder photocatalysts nanofiber coatings photocatalysts can be much easier removed from solution after the photocatalysis process. Such coatings with relative large specific surface area are with higher potential application in industry.

Enhanced interfacial strength of aramid fiber reinforced composites through adsorbed aramid nanofiber coatings

Aramid fibers are well-known for their excellent tensile properties and low density but are limited in composite applications due to their inert surface which leads to poor interfacial properties. One method that has shown promise in recent years is the application of nanoscale reinforcements to the surface of the fibers to improve mechanical interaction with the matrix. With aramid fibers, it is ideal to perform an interfacial reinforcement utilizing the dense hydrogen bonding which is responsible for the fibers strength. Here, it is demonstrated that recently developed aramid nanofibers (ANFs) can adsorb onto the surface of macroscale aramid fibers to enhance the interfacial properties through mechanical interlocking with the matrix. A simple and rapid dip-coating process is used to deposit the ANFs on the aramid fiber surface. These ANFs bond with the fiber through physisorption and hydrogen bonding, yielding a 70.27% increase in interfacial shear strength and a 25.6% increase in short beam shear strength in composites prepared by dip-coating unidirectional tape into a solution of ANFs. Notably, the interfacial gains are made while fully preserving the strength of the aramid fiber following the treatment, therefore ensuring in-plane properties of the composite are maintained. This work shows that the introduction of an ANF interphase may present a novel and convenient method to improve the interfacial strength of aramid reinforced composites, enabling cost-effective and simplified production of stronger structural materials.

Osteogenic composite nanocoating based on nanohydroxyapatite, strontium ranelate and polycaprolactone for titanium implants

Abstract Titanium and its alloys are commonly used as dental and bone implant materials. Biomimetic coating of titanium surfaces could improve their osteoinductive properties. In this work, we have developed a novel osteogenic composite nanocoating for titanium surfaces, which provides a natural environment for facilitating adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells (MSCs). Electrospinning was used to produce composite nanofiber coatings based on polycaprolactone (PCL), nano-hydroxyapatite (nHAp) and strontium ranelate (SrRan). Thus, four types of coatings, i.e., PCL, PCL/nHAp, PCL/SrRan, and PCL/nHAp/SrRan, were applied on titanium surfaces. To assess chemical, morphological and biological properties of the developed coatings, EDS, FTIR, XRD, XRF, SEM, AFM, in-vitro cytotoxicity and in-vitro hemocompatibility analyses were performed. Our findings have revealed that the composite nanocoatings were both cytocompatible and hemocompatible; thus PCL/HAp/SrRan composite nanofiber coating led to the highest cell viability. Osteogenic culture of MSCs on the nanocoatings led to the osteogenic differentiation of stem cells, confirmed by alkaline phosphatase activity and mineralization measurements. The findings support the notion that the proposed composite nanocoatings have the potential to promote new bone formation and enhance bone-implant integration.