Search Results (5)

Highly oriented electrospun conductive nanofibrous biocomposites (CNBs) of polylactic acid (PLA) and polyaniline (PANi) are fabricated using electrospinning. At the percolation threshold (φ_c), the growth of continuous paths between PANi particles leads to a steep increase in the electrical conductivity of fibers, and the McLachlan equation is fitted to identify φ_c. Annealing generates additional conductive channels, which lead to higher conductivity for dynamic percolation. For the first time, dynamic percolation is investigated for revealing time-temperature superposition in oriented conductive nanofibrous biocomposites. The crystallinity (χ_c) displays a linear dependence on annealing temperature within the confined fiber of CNBs. The increase in crystallinity due to annealing also increases the Young’s modulus E of CNBs. The present study outlines a reliable approach to determining the conductivity and elasticity of nanofibers that are highly desirable for a wide range of biological tissue applications. Full article

The physical properties, such as the fibre dimension and crystallinity, of cellulose nanofibre (CNF) are significant to its functional reinforcement ability in composites. This study used supercritical carbon dioxide as a fibre bundle defibrillation pretreatment for the isolation of CNF from bamboo, in order to enhance its physical properties. The isolated CNF was characterised through zeta potential, TEM, XRD, and FT-IR analysis. Commercial CNF was used as a reference to evaluate the effectiveness of the method. The physical, mechanical, thermal, and wettability properties of the bamboo and commercial CNF-reinforced PLA/chitin were also analysed. The TEM and FT-IR results showed the successful isolation of CNF from bamboo using this method, with good colloidal stability shown by the zeta potential results. The properties of the isolated bamboo CNF were similar to the commercial type. However, the fibre diameter distribution and the crystallinity index significantly differed between the bamboo and the commercial CNF. The bamboo CNF had a smaller fibre size and a higher crystallinity index than the commercial CNF. The results from the CNF-reinforced biocomposite showed that the physical, mechanical, thermal, and wettability properties were significantly different due to the variations in their fibre sizes and crystallinity indices. The properties of bamboo CNF biocomposites were significantly better than those of commercial CNF biocomposites. This indicates that the physical properties (fibre size and crystallinity) of an isolated CNF significantly affect its reinforcement ability in biocomposites. The physical properties of isolated CNFs are partly dependent on their source and production method, among other factors. These composites can be used for various industrial applications, including packaging. Full article

The degradation and mechanical properties of potential polymeric materials used for green manufacturing are significant determinants. In this study, cellulose nanofibre was prepared from Schizostachyum brachycladum bamboo and used as reinforcement in the PLA/chitosan matrix using melt extrusion and compression moulding method. The cellulose nanofibre(CNF) was isolated using supercritical carbon dioxide and high-pressure homogenisation. The isolated CNF was characterised with transmission electron microscopy (TEM), FT-IR, zeta potential and particle size analysis. The mechanical, physical, and degradation properties of the resulting biocomposite were studied with moisture content, density, thickness swelling, tensile, flexural, scanning electron microscopy, thermogravimetry, and biodegradability analysis. The TEM, FT-IR, and particle size results showed successful isolation of cellulose nanofibre using this method. The result showed that the physical, mechanical, and degradation properties of PLA/chitosan/CNF biocomposite were significantly enhanced with cellulose nanofibre. The density, thickness swelling, and moisture content increased with the addition of CNF. Also, tensile strength and modulus; flexural strength and modulus increased; while the elongation reduced. The carbon residue from the thermal degradation and the glass transition temperature of the PLA/chitosan/CNF biocomposite was observed to increase with the addition of CNF. The result showed that the biocomposite has potential for green and sustainable industrial application. Full article

Cellulose has been one of the most widespread materials due to its renewability, excellent mechanical properties, biodegradability, high absorption ability, biocompatibility and cheapness. Novel, simple and green colorimetric fibrous film sensor was developed by immobilization of urease enzyme (U) and tricyanofuran hydrazone (TCFH) molecular probe onto cellulose nanofibers (CNF). Cellulose acetate nanofibers (CANF) were firstly prepared from cellulose acetate using the simple, green and low cost solution blowing spinning technology. The produced CANF was exposed to deacetylation to introduce CNF, which was then treated with a mixture of TCFH and urease enzyme to introduce CNF-TCFH-U nanofibrous biosensor. CNF were reinforced with tricyanofuran hyrazone molecular probe and urease enzyme was encapsulated into calcium alginate biopolymer to establish a biocomposite film. This CNF-TCFH-U naked-eye sensor can be applied as a disposable urea detector. CNF demonstrated a large surface area and was utilized as a carrier for TCFH, which is the spectroscopic probe and urease is a catalyst. The biochromic CNF-TCFH-U nanofibrous biosensor responds to an aqueous medium of urea via a visible color signal changing from off-white to dark pink. The morphology of the generated CNF and CNF-TCFH-U nanofibrous films were characterized by different analytical tools, including energy-dispersive X-ray patterns (EDX), polarizing optical microscope (POM), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). SEM images of CNF-TCFH-U nanofibers demonstrated diameters between 800 nm and 2.5 μm forming a nonwoven fabric with a homogeneous distribution of TCFH/urease-containing calcium alginate nanoparticles on the surface of CNF. The morphology of the cross-linked calcium alginate nanoparticles was also explored using transmission electron microscopy (TEM) to indicate an average diameter of 56–66 nm. The photophysical performance of the prepared CNF-TCFH-U was also studied by CIE Lab coloration parameters. The nanofibrous film biosensor displayed a relatively rapid response time (5–10 min) and a limit of detection as low as 200 ppm and as high as 1400 ppm. Tricyanofuran hydrazone is a pH-responsive disperse dye comprising a hydrazone detection group. Determination of urea occurs through a proton transfer from the hydrazone group to the generated ammonia from the reaction of urea with urease. Full article

Silk fibroin has attracted great interest in tissue engineering because of its outstanding biocompatibility, biodegradability and minimal inflammatory reaction. In this study, two kinds of biocomposites based on regenerated silk fibroin are fabricated by electrospinning and post-treatment processes, respectively. Firstly, regenerated silk fibroin/tetramethoxysilane (TMOS) hybrid nanofibers with high hydrophilicity are prepared, which is superior for fibroblast attachment. The electrospinning process causes adjacent fibers to ‘weld’ at contact points, which can be proved by scanning electron microscope (SEM). The water contact angle of silk/tetramethoxysilane (TMOS) composites shows a sharper decrease than pure regenerated silk fibroin nanofiber, which has a great effect on the early stage of cell attachment behavior. Secondly, a novel tissue engineering scaffold material based on electrospun silk fibroin/nano-hydroxyapatite (nHA) biocomposites is prepared by means of an effective calcium and phosphate (Ca–P) alternate soaking method. nHA is successfully produced on regenerated silk fibroin nanofiber within several min without any pre-treatments. The osteoblastic activities of this novel nanofibrous biocomposites are also investigated by employing osteoblastic-like MC3T3-E1 cell line. The cell functionality such as alkaline phosphatase (ALP) activity is ameliorated on mineralized silk nanofibers. All these results indicate that this silk/nHA biocomposite scaffold material may be a promising biomaterial for bone tissue engineering. Full article