Carboxymethyl sago starch based hydrogel for drug delivery application

Chemically modified sago starch into carboxymethyl sago starch (CMSS) was done by using carboxymethylation reaction. The reaction times are varied to determine the optimum degree of substitution (DS) and reaction efficiency (RE). CMSS prepared via carboxymethylation for 3 hours show the highest DS and RE. The CMSS hydrogel was prepared using citric acid as cross-linker. The effects of the preparation condition of CMSS hydrogel such as the percentage of citric acid (w/w), cross-linking periods and cross-linking temperature on the gel fraction were investigated. The swelling study was carried out in distilled water, acidic, neutral and alkaline medium. The release behaviour of methylene blue (MB) as the drug model demonstrates that CMSS hydrogel has potential to be use in drug delivery applications

Preparation and characterizations of poly (aniline-co-m-aminobenzoic acid) / polystyrene composite nanofibers and films

In this research, a simple method was used to synthesize poly(aniline-co-m-aminobenzoic acid) also known as P(ANI-co- m-ABA) composite polystyrene (PS) nanofibers by using in situ chemical polymerization technique. The copolymer was polymerized on electrospun PS nanofibers mats with varied monomers solution concentration and the polymerization time. P(ANI-co-m-ABA) was also polymerized on PS films were prepared for comparison. The conductivity of the composites was studied and the result showed addition of graphene (GP) into the composites improved the conductivity of the composites. The composites of P(ANI-co-m-ABA)/PS nanofibers and films were characterized by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and ultraviolet visible (UV-vis) spectroscopy. Surface morphology of the composite was studied by scanning electron microscopy (SEM)

PAN/lignin/TEOS nanofibers as precursor for the production of carbon nanofibers

Carbon nanofibers (CNF) is widely applied as heat-management materials, composite reinforcement, filtration membrance, and energy storage. Polyacrylonitrile (PAN) is the main precursor for fabrication of CNF due to its brilliant properties such as high specific surface area, high aspect ratio, high mechanical strength and flexibility. However, the manufacturing prices is high. Low-cost carbon nanofibers can be fabricated from renewable materials such as lignin. It is a second most abundant raw material on earth and can be obtained easily. Tetraethyl orthosilicate (TEOS) can be added into the CNF as pore generator to generate more porous surface and catalyze the stabilization process. Porous surface is very important in providing the CNF with high electrical performance such as improved electric double-layer capacitance in supercapacitor. In this study, lignin/PAN/TEOS carbon nanofibers was lignin/PAN/TEOS carbon nanofibers were prepared by using electrospinning method followed by the heat treatment of the up to 1000°C. Electrospun nanofibers were characterized by TGA, DSC and SEM while the carbon nanofibers were characterized by using FTIR and FESEM. The TGA results show that the major degradation temperature decreased to around 270-280°C after lignin is added due to the lower thermal stability of lignin. DSC results show the addition of TEOS shifted the exothermic peaks to lower temperature due to catalytic ability of TEOS. This indicated that the stabilization process of TEOS-incorporated CNF is kinetically higher than those without TEOS. SEM images show the morphology and diameter of the sample which decreased as the lignin concentration was increased. IR spectra show peaks around 1100 cm-1 which is correspond to Si-O-C bond. This indicated the successful formation of Si-O-C/Si-O-Si structures which will influence the properties of CNF such as electrochemical performances. FESEM shows the fiber diameter decreased as TEOS amount increased and pores were successfully produced at the surface of carbon nanofibers

Electrospun carboxymethyl sago starch/poly (ethylene oxide) (CMSS/PEO) hydrogel nanofiber

Sago starch is one of the natural polymers with great values as a polymeric device for various applications due to its potential as biocompatible materials. Producing sago starch nanofibers could enhance the efficiency of sago starch due to its large surface area per volume. Electrospinning is a technique that able to produce micro- to nano-scale fibers, cost effective and applicable to a large variety of materials. In present study, the sago starch was modified into carboxymethyl sago starch (CMSS) prior electrospun into nanofibers to improve properties of the sago starch, such as solubility in cold water. Carboxymethyl sago starch/poly (ethylene oxide) (CMSS/PEO) composite nanofibers were prepared using electrospinning technique with various CMSS/PEO blend solution concentrations from 2.5 to 10.0 w/v%. CMSS/PEO hydrogel films were also prepared and studied for comparison. The SEM results show the increasing of concentration of CMSS/PEO solution mixture, the formation of bead in the nanofibers reduced significantly. It indicates that the incorporation of PEO could reduce the formation of beads of the nanofibers. The electrospun fiber diameter is in the range of 300 nm to 1 μm with random orientation. The CMSS/PEO hydrogel nanofibers were successfully prepared by crosslinked using a non-toxic and natural component, citric acid. The crosslinking reaction was optimized by varying the ratio of PEO to CMS percentage of citric acid (w/w), crosslinking temperature and crosslinking period to get the highest swelling ratio of the hydrogel nanofiber. The optimized swelling ratio of CMSS/PEO hydrogel for each parameter varied from 9.442 to 5.649. The CMSS/PEO hydrogels was evaluated for the possible use in drug delivery systems. In this respect, the release properties of methylene blue (MB) indicator, as a drug model, was investigated

Electrospinning of poly(vinyl) alcohol nanofibers containing mesoporous silica nanoparticles

This study reports on the preparation of nanoparticles subsequently incorporated into the nanofibers. Nanofibers based on Poly(vinyl) alcohol (PVA) containing mesoporous silica nanoparticles (MSNs) were successfully prepared by the electrospinning method. MSNs were synthesized by co-condensation method with average particles size of ~70 nm. Ionic liquid of 1-hexadecylpyridinium bromide (C16PyBr) was used as a template to prepare silica coated MSNs. The effect incorporation of MSNs into the polymer solution to form fibrous structure was studied. Two solvents were used to explore the effect of dispersion nanoparticles in nanofibers. The morphologies, diameter and structure of nanoparticles and electrospun nanofibers were evaluated by Transmission electron microscopy (TEM) and Field emission scanning electron microscope (FESEM). The results showed that MSNs have good dispersion in the PVA nanofibers by using acetone as a solvent, therefore this co-delivery system could be an effective carrier for controllable delivery of drug

Electrospun polyacrylonitrile/lignin/poly(Ethylene Glycol)-based porous activated carbon nanofiber for removal of Nickel(II) ion from aqueous solution

The issue of heavy metal contamination has caused a great deal of concern among water quality experts today, as it contributes to water pollution. Activated carbon nanofibers (ACNFs) showed a significant ability in removing heavy metals from the wastewater. In this study, polyacrylonitrile (PAN) was blended and electrospun with an abundant and inexpensive biopolymer, lignin and a water soluble polymer, poly(ethylene glycol) (PEG), by using an electrospinning technique to form nanofibers. The electrospun nanofibers were then investigated as a precursor for the production of porous ACNFs to study the removal of nickel(II) ions by adsorption technique. PEG was added to act as a porogen and to create the porous structure of carbon nanofibers (CNFs). CNFs were prepared by thermal treatment of the electrospun nanofibers and followed by activation of CNFs by thermal and acid treatment on CNFs. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) spectral analysis of the ACNFs showed a strong absorption peak of the C-O functional group, indicating the increase in the oxygenated compound. Field emission scanning electron microscopy (FESEM) images concluded that the ACNFs have more porous and compact fibers with a smaller fiber diameter of 263 ± 11 nm, while the CNFs are less compact and have slightly larger fiber diameter of 323 ± 6 nm. The adsorption study showed that the ACNFs possessed a much higher adsorption capacity of 18.09 mg/g compared with the CNFs, which the amount adsorbed was achieved only at 2.7 mg/g. The optimum adsorption conditions that gave the highest percentage of 60% for nickel(II) ions removal were 50 mg of adsorbent dosage, 100 ppm of nickel(II) solution, pH 3, and a contact time of 60 min. The study demonstrated that the fabrication of ACNFs from PAN/lignin/PEG electrospun nanofibers have potential as adsorbents for the removal of heavy metal contaminants

Preparation and thermal properties of cellulose acetate/polystyrene blend nanofibers via electrospinning technique

Cellulose acetate (CA) is an interesting material due to its wide spectrum of utilities across different domains ranging from absorbent to membrane filters. In this study, polystyrene (PS) nanofibres, and cellulose acetate/polystyrene (CA/PS) blend nanofibres with various ratios of CA: PS from 20: 80 to 80: 20 were fabricated by using electrospinning technique. The SEM images show that the nanofibres exhibited non-uniform and random orientation with the average fibre diameter in the range of 100 to 800 nm. It was found that the incorporation of PS had a great effect on the morphology of nanofibre. At high proportion of PS, no or less beaded CA/PS nanofibres were formed. Thermal properties of the composite nanofibres were investigated by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. The TGA results showed thermal stability of CA/PS nanofibres were higher than pristine CA

Ternary functionalised carbon nanofiber/polypyrrole/manganese oxide as high specific energy electrode for supercapacitor

A successful fabrication of ternary functionalised carbon nanofibers/polypyrrole/manganese oxide (f-CNFs/PPy/MnO₂) composite was reported. The field emission scanning electron microscopy (FESEM) image had revealed a random distribution of granular PPy and spherical nanoparticles of MnO2 on the surface of f-CNFs. The measured contact angle of f-CNFs indicated superhydrophilic nature which can enhance the surface wettability and ionic diffusion. The ternary f-CNFs/PPy/MnO₂ composite displayed a remarkable specific capacitance of 409.88 F/g compared with f-CNFs/MnO₂ (322.96 F/g) and f-CNFs/PPy (290.83 F/g). The electrochemical properties of f-CNFs/PPy/MnO₂ had contributed to the appreciable specific energy of 42.53 Wh/kg at a specific power of 297.32 W/kg. The assembled f-CNFs/PPy/MnO₂ composite also showed low resistance of charge transfer (Rct) value (3.40 Ω) with a better cycle life (86.30% capacitance retention over 3000 cycles). Hence, ternary f-CNFs/PPy/MnO₂ can be suggested as a high-performance electrode for supercapacitor

Enhancement of electrochemical performance based on symmetrical poly-(3,4-ethylenedioxythiophene) coated polyvinyl alcohol/graphene oxide/manganese oxide microfiber for supercapacitor

In this study, a symmetrical poly (3, 4-ethylenedioxythiophene) (PEDOT) coated on poly (vinyl alcohol) (PVA)-graphene oxide (GO)-manganese oxide (MnO2) microfibers (PVA-GO-MnO2/PEDOT) supercapacitor was successfully prepared using a combination of two facile techniques; electrospinning and electropolymerisation. The FESEM analysis revealed the uniform distribution of manganese oxide nanoparticles on the surface of cross-linking PVA-GO microfibers and a cauliflower-like morphology was observed upon deposition of PEDOT on the surface of PVA-GO-MnO2 microfibers. The chemical composition of PVA-GO-MnO2/PEDOT and oxidation state of manganese were characterised using Raman and X-Ray photoelectron spectroscopies. The inclusion of MnO2 and PEDOT in the microcomposite proved the enhancement of specific capacitance where PVA-GO-MnO2/PEDOT exhibited a specific capacitance of 144.66 F/g compared to PVA-MnO2/PEDOT (107.22 F/g), PVA-GO/PEDOT (94.73 F/g) and PEDOT (62.86 F/g). A wide potential window (1.8 V) was achieved for PVA-GO-MnO2/PEDOT with an excellent capacitance retention of 91.18% suggesting an ideal capacitive behaviour and good cycling stability. PVA-GO-MnO2/PEDOT microcomposite also showed an improved specific energy and specific power with small equivalent series resistance (34.5 Ω) and charge transfer resistance (0.62 Ω). This demonstrated that symmetric electrode of PVA-GO-MnO2/PEDOT can offer a great promise in producing high-performance supercapacitors

Supercapacitor with superior electrochemical properties derived from symmetrical manganese oxide-carbon fiber coated with polypyrrole

A supercapacitor electrode comprising conducting polypyrrole (PPy) coated on manganese oxide-carbon fiber (CNFMnO2) was successfully synthesized using electrospinning, followed by carbonization and in-situ polymerization. A non-uniform distribution of PPy on the surface of CNFMnO2 was observed via FESEM analysis. The chemical bonding of CNFMnO2/PPy and the valence state of manganese were revealed via FTIR, Raman spectroscopy, XRD and XPS measurements. CNFMnO2/PPy composite possessed high specific capacitance and specific energy of 315.80 Fg−1 and 13.68 Wh/kg, respectively. In addition, good electrochemical reversibility was proven upon CNFMnO2/PPy even at higher sweep rate (5–200 mV/s). Moreover, this one-dimensional electrode achieved an excellent long-term cycling stability (82.46%) over 2000 CV cycles with low charge transfer resistance (4.61 Ω). The modification of CNFMnO2/PPy contributes to good synergistic effects among the material which improve the electrochemical behavior of manganese oxide-based fiber composite for future supercapacitor