The aim of this research is to develop biocompatible nanofibrous mats using hydroxyethyl cellulose with improved cellular adhesion profiles and stability and use these fibrous mats as potential scaffold for skin tissue engineering. Glutaraldehyde was used to treat the scaffolds water insoluble as well as improve their biostability for possible use in biomedical applications. Electrospinning of hydroxyethyl cellulose (5 wt%) with poly(vinyl alcohol) (15 wt%) incorporated with and without collagen was blended at (1:1:1) and (1:1) ratios, respectively, and was evaluated for optimal criteria as tissue engineering scaffolds. The nanofibrous mats were crosslinked and characterized by scanning electron microscope, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Scanning electron microscope images showed that the mean diameters of blend nanofibers were gradually increased after chemically crosslinking with glutaraldehyde. Fourier transform infrared spectroscopy was carried out to understand chemical interactions in the presence of aldehyde groups. Thermal characterization results showed that the stability of hydroxyethyl cellulose/poly(vinyl alcohol) and hydroxyethyl cellulose/poly(vinyl alcohol)/collagen nanofibers was increased with glutaraldehyde treatment. Studies on cell-scaffolds interaction were carried out by culturing human fibroblast (hFOB) cells on the nanofibers by assessing the growth, proliferation, and morphologies of cells. The scanning electron microscope results show that better cell proliferation and attachment appeared on hydroxyethyl cellulose/poly(vinyl alcohol)/collagen substrates after 7 days of culturing, thus, promoting the potential of electrospun scaffolds as a promising candidate for tissue engineering applications.
In this study, a novel fibrous membrane of hydroxyethyl cellulose (HEC)/poly(vinyl alcohol) blend was successfully fabricated by electrospinning technique and characterized. The concentration of HEC (5%) with PVA (15%) was optimized, blended in different ratios (30-50%) and electrospun to get smooth nanofibers. Nanofibrous membranes were made water insoluble by chemically cross-linking by glutaraldehyde and used as scaffolds for the skin tissue engineering. The microstructure, morphology, mechanical and thermal properties of the blended HEC/PVA nanofibrous scaffolds were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, differential scanning colorimetry, universal testing machine and thermogravimetric analysis. Cytotoxicity studies on these nanofibrous scaffolds were carried out using human melanoma cells by the MTT assays. The cells were able to attach and spread in the nanofibrous scaffolds as shown by the SEM images. These preliminary results show that these nanofibrous scaffolds that supports cell adhesion and proliferation is promising for skin tissue engineering.
Electrospinning of hydroxyapatite (HA)/polyvinyl butyral solution resulted in the formation of fibers with average diameter of 937-1440 nm. These fibers were converted into HA nanoparticles with size <100 nm after undergoing calcination treatment at 600°C. The diameter of the fiber was found to be influenced by applied voltage and spinning distance. The injection flowrate did not affect the diameter significantly. The electrospinning method successfully reduced the commercial HA particle size in the range of 400-1100 nm into <100 nm. The dispersion of the finally calcined HA nanoparticles was improved significantly after anionic sodium dodecyl sulfate surfactant was introduced. The experimental data of HA growth kinetics were subjected to the integral method of analysis, and the rate law of the reaction was found to follow the first order reaction.
A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW) resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%.
Point-of-care biosensors are important tools developed to aid medical diagnosis and testing, food safety and environmental monitoring. Paper-based biosensors, especially nucleic acid-based lateral flow assays (LFA), are affordable, simple to produce and easy to use in remote settings. However, the sensitivity of such assays to infectious diseases has always been a restrictive challenge. Here, we have successfully electrospun polycaprolactone (PCL) on nitrocellulose (NC) membrane to form a hydrophobic coating to reduce the flow rate and increase the interaction rate between the targets and gold nanoparticles-detecting probes conjugates, resulting in the binding of more complexes to the capture probes. With this approach, the sensitivity of the PCL electrospin-coated test strip has been increased by approximately ten-fold as compared to the unmodified test strip. As a proof of concept, this approach holds great potential for sensitive detection of targets at point-of-care testing.
Two different liquid assisted processing methods: internal melt-blending (IMB) and twin-screw extrusion (TWS) were performed to fabricate polyethylene (PE)/cellulose nanofiber (CNF) nanocomposites. The nanocomposites consisted maleic anhydride-grafted PE (PEgMA) as a compatibilizer, with PE/PEgMA/CNF ratio of 97/3/0.5-5 (wt./wt./wt.), respectively. Morphological analysis exhibited that CNF was well-dispersed in nanocomposites prepared by liquid-assisted TWS. Meanwhile, a randomly oriented and agglomerated CNF was observed in the nanocomposites prepared by liquid-assisted IMB. The nanocomposites obtained from liquid-assisted TWS exhibited the best mechanical properties at 3 wt.% CNF addition with an increment in flexural strength by almost 139%, higher than that of liquid-assisted IMB. Results from this study indicated that liquid feeding of CNF assisted the homogenous dispersion of CNF in PE matrix, and the mechanical properties of the nanocomposites were affected by compounding method due to the CNF dispersion and alignment.
This study aimed to develop a novel electrospun polyacrylonitrile (PAN) nanofiber membrane with the enhanced antibacterial property. The PAN nanofiber membrane was first subjected to alkaline hydrolysis treatment, and the treated membrane was subsequently grafted with chitosan (CS) to obtain a CS-modified nanofiber membrane (P-COOH-CS). The modified membrane was then coupled with different dye molecules to form P-COOH-CS-Dye membranes. Lastly, poly(hexamethylene biguanide) hydrochloride (PHMB) was immobilized on the modified membrane to produce P-COOH-CS-Dye-PHMB. Physical characterization studies were conducted on all the synthesized nanofiber membranes. The antibacterial efficacies of nanofiber membranes prepared under different synthesis conditions were evaluated systematically. Under the optimum synthesis conditions, P-COOH-CS-Dye-PHMB was highly effective in disinfecting a high concentration of Escherichia coli, with an antibacterial efficacy of approximately 100%. Additionally, the P-COOH-CS-Dye-PHMB exhibited an outstanding wash durability as its antibacterial efficacy was only reduced in the range of 5%-7% even after 5 repeated cycles of treatment. Overall, the experimental results of this study suggested that the P-COOH-CS-Dye-PHMB is a promising antibacterial nanofiber membrane that can be adopted in the food, pharmaceutical, and textile industries.
N-[(2-hydroxyl-3-trimethylammonium) propyl] chitosan chloride (HTCC), which is a type of chitosan derivative with quaternary ammonium groups, possesses a higher antibacterial activity as compared to the pristine chitosan. The nanofiber membranes made of HTCC are attractive for applications demanding for antibacterial function. However, the hydrophilic nature of HTCC makes it unsuitable for electrospinning of nanofibers. Hence, biodegradable polyvinyl alcohol (PVA) was proposed as an additive to improve the electrospinnability of HTCC. In this work, PVA/HTCC nanofiber membrane was crosslinked with the blocked diisocyanate (BI) to enhance the stability of nanofiber membrane in water. Microbiological assessments showed that the PVA/HTCC/BI nanofiber membranes possessed a good antibacterial efficacy (∼100 %) against E. coli. Moreover, the biocompatibility of PVA/HTCC/BI nanofiber membrane was proven by the cytotoxicity test on mouse fibroblasts. These promising results indicated that the PVA/HTCC/BI nanofiber membrane can be a promising material for food packaging and as a potential wound dressing for skin regeneration.
Vitamin D deficiency is now a global health problem; despite several drug delivery systems for carrying vitamin D due to low bioavailability and loss bioactivity. Developing a new drug delivery system to deliver vitamin D3 is a strong incentive in the current study. Hence, an implantable drug delivery system (IDDS) was developed from the electrospun cellulose acetate (CA) and ε-polycaprolactone (PCL) nanofibrous membrane, in which the core of implants consists of vitamin D3-loaded CA nanofiber (CAVD) and enclosed in a thin layer of the PCL membrane (CAVD/PCL). CA nanofibrous mat loaded with vitamin D3 at the concentrations of 6, 12, and 20% (w/w) of vitamin D3 were produced using electrospinning. The smooth and bead-free fibers with diameters ranged from 324 to 428 nm were obtained. The fiber diameters increased with an increase in vitamin D3 content. The controlled drug release profile was observed over 30-days, which fit with the zero-order model (R2 > 0.96) in the first stage. The mechanical properties of IDDS were improved. Young's modulus and tensile strength of CAVD/PCL (dry) were161 ± 14 and 13.07 ± 2.5 MPa, respectively. CA and PCL nanofibers are non-cytotoxic based on the results of the in-vitro cytotoxicity studies. This study can further broaden in-vivo study and provide a reference for developing a new IDDS to carry vitamin D3 in the future.
Cellulose acetate (CA) is a remarkable biomaterial most extensively used in biomedical applications due to their properties. This review highlighted the synthesis and chemical structure of CA polymer as well as focused on the mechanical, chemical, thermal, biocompatible, and biodegradable properties of electrospun CA nanofibers. These properties are essential in the evaluation of the CA nanofibers and provide information as a reference for the further utilization and improvement of CA nanofibers. Moreover, we have summarized the use of electrospun CA nanofibers in the drug delivery system as a carrier for drugs and classify them according to the drug class, including anti-inflammatory, anticancer, antioxidant, antimicrobial agents, vitamins and amino acids. Our review has been concluded that CA nanofibers cannot wholly be biodegraded within the human body due to the absence of cellulase enzyme but degraded by microorganisms. Hence, the biodegradation of CA nanofibers in vivo has addressed as a critical challenge.
The main focus of this study is the incorporation of collagen peptides to fabricate P(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] nano-fiber construct to further enhance surface wettability and support cell growth while harbouring desired properties for biodegradable wound dressing. Simultaneous electrospinning of nanofiber P(3HB-co-4HB)/collagen peptides construct was carried out using dual syringe system. The wettability of the constructs increased with the increase in 4HB molar fraction from 20mol% 4HB [53.2°], P(3HB-co-35mol%4HB)[48.9°], P(3HB-co-50mol%4HB)[44.5°] and P(3HB-co-82mol%4HB) [37.7°]. In vitro study carried out using mouse fibroblast cells (L929) grown on nanofiber P(3HB-co-4HB)/collagen peptides construct showed an increase in cell proliferation. In vivo study using animal model (Sprague Dawley rats) showed that nanofibrous P(3HB-co-4HB)/collagen peptides construct had a significant effect on wound contractions with the highest percentage of wound closure of 79%. Hence, P(3HB-co-4HB)/collagen peptides construct suitable for wound dressing have been developed using nano-fabrication technique.
Immortalized liver cell lines and primary hepatocytes are currently used as in vitro models for hepatotoxic drug screening. However, a decline in the viability and functionality of hepatocytes with time is an important limitation of these culture models. Advancements in tissue engineering techniques have allowed us to overcome this challenge by designing suitable scaffolds for maintaining viable and functional primary hepatocytes for a longer period of time in culture. In the current study, we fabricated liver-specific nanofiber scaffolds with polylactic acid (PLA) along with a decellularized liver extracellular matrix (LEM) by the electrospinning technique. The fabricated hybrid PLA-LEM scaffolds were more hydrophilic and had better swelling properties than the PLA scaffolds. The hybrid scaffolds had a pore size of 38 ± 8 μm and supported primary rat hepatocyte cultures for 10 days. Increased viability (2-fold increase in the number of live cells) and functionality (5-fold increase in albumin secretion) were observed in primary hepatocytes cultured on the PLA-LEM scaffolds as compared to those on conventional collagen-coated plates on day 10 of culture. A significant increase in CYP1A2 enzyme activity was observed in hepatocytes cultured on PLA-LEM hybrid scaffolds in comparison to those on collagen upon induction with phenobarbital. Drugs like acetaminophen and rifampicin showed the highest toxicity in hepatocytes cultured on hybrid scaffolds. Also, the lethal dose of these drugs in rodents was accurately predicted as 1.6 g/kg and 594 mg/kg, respectively, from the corresponding IC50 values obtained from drug-treated hepatocytes on hybrid scaffolds. Thus, the fabricated liver-specific electrospun scaffolds maintained primary hepatocyte viability and functionality for an extended period in culture and served as an effective ex vivo drug screening platform to predict an accurate in vivo drug-induced hepatotoxicity.
In the last decade, magnesium alloys have been considered as absorbable metals for biomedical applications, while some have reached their clinical use as temporary bone implants. However, their widespread use is still limited by its strength and degradability. One way of improvement can be done by reinforcing magnesium alloys with carbon nanofibres to form composites. This work aims at developing carbon nanofibre-reinforced magnesium-zinc (Mg-Zn/CNF) composites with optimum strength and degradability while ensuring their biocompatibility. A response surface method was used to determine their optimum process parameters (composition, compaction pressure, and sintering temperature), and analyse the resulting properties (elastic modulus, hardness, weight loss, and cytocompatibility). Results showed that the optimal parameters were reached at 1.8% of CNF, 425 MPa of compaction pressure, and 500 °C of sintering temperature, whereby it gave an elastic modulus of 5 GPa, hardness of 60 Hv, and a weight loss of 51% after three days immersion in PBS. The composites exhibited a hydrophobic surface that controlled the liberation of Mg2+ and Zn2+ ions, leading to more than 70% osteoblast cells viability up to seven days of incubation. This study can also serve as a starting point for future researchers interested in finding methods to fabricate Mg-Zn/CNF composites with high mechanical characteristics, corrosion resistance, and biocompatibility.
Introduction: Diabetic foot ulcer (DFU) is the most distressing complication of diabetes mellitus and often associated with risk of non-traumatic lower extremity amputations. Available formulations and wound dressings for DFU treatment are unfortunately less effective both on controlling and healing DFU. Issues commonly found are associated with providing an optimum environment which facilitates healing process; moist environment, effective oxygen exchange, preventing infection, controlling exudate and also patients compliance. The challenge is therefore to develop a novel drug delivery which address this unmet medical need for better wound treatment of chronic and slow healing DFU. This study aimed to develop a biomaterial based nanofibrous wound dressing formulation containing deferoxamine (DFO), which reported as a potential therapeutic approach to improve wound healing. Deferoxamine regulates the expression and increase stability of hypoxia-inducible factor-1α (HIF-1 α), growthfactor that crucial in wound repair, and thus increase neovascularization. Preparation and characterization of chosen polymers; chitosan/ alginate/polyvinyl alcohol (PVA) for nanofiber formulation will be carried out. Such biodegradable polymer nanofiber is a great benefit for drug delivery owing to its high surface area to volume ratio and high porosity which creates ideal environment to aid in wound healing. Methods: Nanofibers loaded DFO will be fabricated by electrospinning
method that utilizes electrostatic force to produce fine fibers from the polymeric solution. Results: Various polymers concentrations and ratios are investigated to obtain the desired fibers characteristics. The selected optimized DFO nanofibers will be studied for its efficacy in wound healing through in-vivo animal studies. Conclusion: The proposed formulation would be an ideal low cost novel wound dressing with improved healing potential for efficient treatment
of diabetic foot ulcer.
Electrospinning is a common method to prepare nanofiber scaffolds for tissue engineering. One of the common cellulose esters, cellulose acetate butyrate (CAB), has been electrospun into nanofibers and studied. However, the intrinsic hydrophobicity of CAB limits its application in tissue engineering as it retards cell adhesion. In this study, the properties of CAB nanofibers were improved by fabricating the composite nanofibers made of CAB and hydrophilic polyethylene glycol (PEG). Different ratios of CAB to PEG were tested and only the ratio of 2:1 resulted in smooth and bead-free nanofibers. The tensile test results show that CAB/PEG composite nanofibers have 2-fold higher tensile strength than pure CAB nanofibers. The hydrophobicity of the composite nanofibers was also reduced based on the water contact angle analysis. As the hydrophilicity increases, the swelling ability of the composite nanofiber increases by 2-fold with more rapid biodegradation. The biocompatibility of the nanofibers was tested with normal human dermal fibroblasts (NHDF). The cell viability assay results revealed that the nanofibers are non-toxic. In addition to that, CAB/PEG nanofibers have better cell attachment compared to pure CAB nanofibers. Based on this study, CAB/PEG composite nanofibers could potentially be used as a nanofiber scaffold for applications in tissue engineering.
Two important criteria of an ideal biomaterial in the field of stem cells research are to regulate the cell proliferation without the loss of its pluripotency and to direct the differentiation into a specific cell lineage when desired. The present study describes the influence of TiO2 nanofibrous surface structures on the regulation of proliferation and stemness preservation of adipose-derived stem cells (ADSCs). TiO2 nanofiber arrays were produced in situ onto Ti-6Al-4V substrate via a thermal oxidation process and the successful fabrication of these nanostructures was confirmed by field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and contact angle measurement. ADSCs were seeded on two types of Ti-6Al-4V surfaces (TiO2 nanofibers and flat control), and their morphology, proliferation, and stemness expression were analyzed using FESEM, AlamarBlue assay, flow cytometry, and quantitative real-time polymerase chain reaction (qRT-PCR) after 2 weeks of incubation, respectively. The results show that ADSCs exhibit better adhesion and significantly enhanced proliferation on the TiO2 nanofibrous surfaces compared to the flat control surfaces. The greater proliferation ability of TiO2 nanofibrous surfaces was further confirmed by the results of cell cycle assay. More importantly, TiO2 nanofibrous surfaces significantly upregulate the expressions of stemness markers Sox-2, Nanog3, Rex-1, and Nestin. These results demonstrate that TiO2 nanofibrous surfaces can be used to enhance cell adhesion and proliferation while simultaneously maintaining the stemness of ADSCs, thereby representing a promising approach for their potential application in the field of bone tissue engineering as well as regenerative therapies.
One of the major challenges in bone grafting is the lack of sufficient bone vascularization. A rapid and stable bone vascularization at an early stage of implantation is essential for optimal functioning of the bone graft. To address this, the ability of in situ TiO2 nanofibrous surfaces fabricated via thermal oxidation method to enhance the angiogenic potential of human umbilical vein endothelial cells (HUVECs) was investigated. The cellular responses of HUVECs on TiO2 nanofibrous surfaces were studied through cell adhesion, cell proliferation, capillary-like tube formation, growth factors secretion (VEGF and BFGF), and angiogenic-endogenic-associated gene (VEGF, VEGFR2, BFGF, PGF, HGF, Ang-1, VWF, PECAM-1 and ENOS) expression analysis after 2 weeks of cell seeding. Our results show that TiO2 nanofibrous surfaces significantly enhanced adhesion, proliferation, formation of capillary-like tube networks and growth factors secretion of HUVECs, as well as leading to higher expression level of all angiogenic-endogenic-associated genes, in comparison to unmodified control surfaces. These beneficial effects suggest the potential use of such surface nanostructures to be utilized as an advantageous interface for bone grafts as they can promote angiogenesis, which improves bone vascularization.
Cellulose nanofibers (CNF) isolated from plant biomass have attracted considerable interests in polymer engineering. The limitations associated with CNF-based nanocomposites are often linked to the time-consuming preparation methods and lack of desired surface functionalities. Herein, we demonstrate the feasibility of preparing a multifunctional CNF-zinc oxide (CNF-ZnO) nanocomposite with dual antibacterial and reinforcing properties via a facile and efficient ultrasound route. We characterized and examined the antibacterial and mechanical reinforcement performances of our ultrasonically induced nanocomposite. Based on our electron microscopy analyses, the ZnO deposited onto the nanofibrous network had a flake-like morphology with particle sizes ranging between 21 to 34 nm. pH levels between 8-10 led to the formation of ultrafine ZnO particles with a uniform size distribution. The resultant CNF-ZnO composite showed improved thermal stability compared to pure CNF. The composite showed potent inhibitory activities against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative Salmonella typhi (S. typhi) bacteria. A CNF-ZnO-reinforced natural rubber (NR/CNF-ZnO) composite film, which was produced via latex mixing and casting methods, exhibited up to 42% improvement in tensile strength compared with the neat NR. The findings of this study suggest that ultrasonically-synthesized palm CNF-ZnO nanocomposites could find potential applications in the biomedical field and in the development of high strength rubber composites.
Nanobiocatalysis is a new frontier of emerging nanosized material support in enzyme immobilization application. This paper is about a comprehensive review on cellulose nanofibers (CNF), including their structure, surface modification, chemical coupling for enzyme immobilization, and potential applications. The CNF surface consists of mainly -OH functional group that can be directly interacted weakly with enzyme, and its binding can be improved by surface modification and interaction of chemical coupling that forms a strong and stable covalent immobilization of enzyme. The knowledge of covalent interaction for enzyme immobilization is important to provide more efficient interaction between CNF support and enzyme molecule. Enzyme immobilization onto CNF is having potential for improving enzymatic performance and production yield, as well as contributing toward green technology and sustainable sources.
Adsorption of lysozyme on the dye-affinity nanofiber membranes was investigated in batch and dynamic modes. The membrane matrix was made of electrospun polyacrylonitrile nanofibers that were grafted with ethylene diamine (EDA) and/or chitosan (CS) for the coupling of Reactive Blue 49 dye. The physicochemical properties of these dye-immobilized nanofiber membranes (P-EDA-Dye and P-CS-Dye) were characterized microscopically, spectroscopically and thermogravimetrically. The capacities of lysozyme adsorption by the dye-affinity nanofiber membranes were evaluated under various conditions, namely pH, dye immobilized density, and loading flow rate. The adsorption of lysozyme to the dye-affinity nanofiber membranes was well fitted by Langmuir isotherm and pseudo-second kinetic models. P-CS-Dye nanofiber membrane had a better performance in the dynamic adsorption of lysozyme from complex chicken egg white solution. It was observed that after five cycles of adsorption-desorption, the dye-affinity nanofiber membrane did not show a significant loss in its capacity for lysozyme adsorption. The robustness as well as high dynamic adsorption capability of P-CS-Dye nanofiber membrane are promising for the efficient recovery of lysozyme from complex feedstock via nanofiber membrane chromatography.