Fabrication and morphology study of electrospun cellulose acetate/polyethylenimine nanofiber

Innovative upcycling cigarette filters into high-performance cellulose nanofiber-epoxy composites

This research introduces a novel upcycling method for transforming cigarette filters-an abundant and persistent environmental waste-into high-performance epoxy composites reinforced with cellulose nanofibers. The innovation lies in extracting cellulose acetate nanofibers from used cigarette butts via a multi-step purification and electrospinning process, followed by their conversion into regenerated cellulose nanofibers through alkaline hydrolysis. This dual-fiber approach allows us to fabricate four distinct epoxy composites, each reinforced by different nanofiber types: recycled cellulose acetate nanofibers, regenerated cellulose nanofibers from recycled cigarette filters, and their commercial counterparts. Notably, this is the first time regenerated nanofibers derived from waste cigarette filters have been utilized for epoxy composite reinforcement, demonstrating a sustainable, high-value use for a major pollutant. Comprehensive characterizations, including FTIR, XRD, SEM, and contact angle measurements, confirmed the successful regeneration of cellulose nanofibers, showing improved hydrophilicity, reduced crystallinity, and uniform nanofiber morphology with diameters between 200 and 300 nm. The innovation further extends to the mechanical performance of these composites: tensile tests revealed that those reinforced with regenerated cellulose nanofibers exhibited superior tensile strength (49.5-53.8 MPa), significantly outperforming both cellulose acetate nanofiber composites (40.1-42.6 MPa) and neat epoxy resin (31.4 MPa). This marked improvement is attributed to enhanced nanofiber dispersion and interfacial adhesion within the epoxy matrix, an essential advancement over traditional composites. In addition, thermal analysis showed that all composites maintained thermal stability in the 300-400 °C range, comparable to commercial alternatives. The regenerated nanofiber-reinforced composites also displayed enhanced optical transparency due to reduced light scattering, making them ideal candidates for applications requiring both mechanical strength and optical clarity. By pioneering the use of cigarette filter waste for fabricating advanced cellulose nanofiber composites, this study presents an eco-friendly approach to addressing environmental pollution while creating sustainable materials with superior mechanical, thermal, and optical properties.

Curcumin loaded waste biomass resourced cellulosic nanofiber cloth as a potential scaffold for regenerative medicine: An in-vitro assessment

This article demonstrates the development of nanofibrous cloths by electrospinning of renewable materials, i.e., curcumin-loaded 90% cellulose acetate (CA)/10% poly(ε-caprolactone) (PCL), for applications in regenerative medicine. The CA is derived from the biomass waste of the oil palm plantation (empty fruit bunch). The nanofiber scaffolds are characterized for the fiber morphology, microstructure, thermal properties, and wettability. The optimized smooth and bead-free electrospun fiber cloth contains 90% CA and 10% PCL in two curcumin compositions (0.5 and 1 wt%). The role of curcumin is shown to be two-fold: the first is its function as a drug and the second is its role in lowering the water contact angle and increasing the hydrophilicity. The hydrophilicity enhancements are related to the hydrogen bonding between the components. The enhanced hydrophilicity contributed to improve the swelling behavior of the scaffolds; the CA/PCL/Cur (0.5%) and the CA/PCL/Cur (1.0%) showed swelling of ~700 and 950%, respectively, in phosphate-buffered saline (PBS). The drug-release studies revealed the highest cumulative drug release of 60% and 78% for CA/PCL/Cur (0.5%) and CA/PCL/Cur (1.0%) nanofibers, respectively. The in-vitro studies showed that CA/PCL/Cur (0.5 wt%) and CA/PCL/Cur (1.0 wt%) nanofiber scaffolds facilitate a higher proliferation and expression of actin in fibroblasts than those scaffolds without curcumin for wound healing applications.

Electrospun gelatin-polyethylenimine blend nanofibrous scaffold for biomedical applications

In this study, gelatin-polyethylenimine blend nanofibers (GEL/PEI) were fabricated via electrospinning with different ratios (9:1, 6:1, 3:1) to integrate the properties of both the polymers for evaluating its biomedical application. From scanning electron microscopy, the average diameter of blend nanofibers (265 ± 0.074 nm to 340 ± 0.088 nm) was observed to be less than GEL nanofibers (403 ± 0.08 nm). The incorporation of PEI with gelatin resulted in improved thermal stability of nanofibers whereas the Young's modulus was observed to be higher at 9:1 ratio when compared with other ratios. The in vitro studies showed that the GEL/PEI nanofibers with 9:1 ratio promoted better cell adhesion and viability. GEL/PEI nanofibers with 9:1 and 6:1 showed hemolysis within the permissible limits. From the results, it could be interpreted that GEL/PEI nanofibers with 9:1 ratio proved to be a better scaffold thereby making them a potential candidate for tissue engineering applications.

Biomimetic Growth of Hydroxyapatite on Electrospun CA/PVP Core⁻Shell Nanofiber Membranes

In this study, cellulose acetate (CA)/polyvinylpyrrolidone (PVP) core⁻shell nanofibers were successfully fabricated by electrospinning their homogeneous blending solution. Uniform and cylindrical nanofibers were obtained when the PVP content increased from 0 to 2 wt %. Because of the concentration gradient associated with the solvent volatilization, the composite fibers flattened when the PVP increased to 5 wt %. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results confirmed the existence of a hydrogen bond between the CA and PVP molecules, which enhanced the thermodynamic properties of the CA/PVP nanofibers, as shown by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results. To analyze the interior structure of the CA/PVP fibers, the water-soluble PVP was selectively removed by immersing the fiber membranes in deionized water. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the PVP component, which has a low surface tension, was driven to the exterior of the fiber to form a discontinuous phase, whereas the high-content CA component inclined to form the internal continuous phase, thereby generating a core⁻shell structure. After the water-treatment, the CA/PVP composite fibers provided more favorable conditions for mineral crystal deposition and growth. Energy-dispersive spectroscopy (EDS) and FTIR proved that the crystal was hydroxyapatite (HAP) and that the calcium to phosphorus ratio was 1.47, which was close to the theoretical value of 1.67 in HAP. Such nanofiber membranes could be potentially applicable in bone tissue engineering.

Three-Dimensional Electrohydrodynamic Printing and Spinning of Flexible Composite Structures for Oral Multidrug Forms

A simple method to rapidly customize and to also mass produce oral dosage forms is arguably a current bottleneck in the development of modern personalized medicine. Specifically, delayed-release mechanisms with well-controlled dosage profiles for combinations of traditional Chinese herbal extracts and Western medications are not well established. Herein, we demonstrate a novel multidrug-loaded membrane sandwich with structures infused with ibuprofen (IBU) and Ganoderma lucidum polysaccharide (GLP) using three-dimensional electrohydrodynamic printing and electrospinning techniques. The resulting flexible membrane consists of microscaled, multilayered cellulose acetate (CA) membranes loaded with IBU in the shape of either concentric squares or circles, as the top and bottom layers of a sandwich structure. In between the CA-IBU layers are randomly electrospun polyvinyl pyrrolidone (PVP) layers loaded with GLP. The complete fibrous membrane sandwich can be folded and embedded into a 0-size capsule to achieve oral compliance. Simulated in vitro testing of gastric and intestinal fluids demonstrated a triphasic release profile. There was an immediate release of GLP after gastric juices dissolved the capsule shell and the PVP, followed by the short-term release of 60% of the IBU within an hour afterward, and the remaining IBU was released in a sustained manner following a Fickian diffusion profile. In summary, this multidrug (both hydrophilic and/or hydrophobic) oral system with precision-designed structures should enable personalized therapeutic dosing.

Laccase-immobilized dendritic nanofibrous membranes as a novel approach towards the removal of bisphenol A

Laccase enzymes from Rhus vernificera were covalently bound on hyperbranched polyethyleneimine/polyethersulfone (HPEI/PES) electrospun nanofibrous membranes and used for the removal of bisphenol A (BPA) from water. The laccase enzyme was anchored on the dendritic membranes through the abundant peripheral amine groups on the HPEI using glutaraldehyde as a crosslinker. The membranes were characterized with attenuated total reflectance-Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and ultraviolet-visible spectroscopy and correlative light and electron microscopy (CLEM). Furthermore, contact-angle analyses, pure water flux measurements and rejection analyses were carried out. CLEM showed that the enzymes were uniformly dispersed on the nanofibres while SEM analysis revealed that the nanofibres had an average diameter of 354 ± 37 nm. EDS showed the presence of Cu, which is the active entity in laccase enzymes. The laccase-modified membranes were hydrophilic (50°-53° contact angle) and exhibited high BPA rejection of 89.6% as compared to the 52.4% demonstrated by pristine PES. The laccase-modified membranes also maintained a constant permeate flux (7.07 ± 5.54 L/m² h) throughout the filtration process. Recyclability studies indicated that the membranes still maintained a high BPA removal of up to 79% even after four filtration cycles.