Emerging Applications of Versatile Polyaniline-Based Polymers in the Food Industry.

Intrinsically conducting polymers (ICPs) have been widely studied in various applications, such as sensors, tissue engineering, drug delivery, and semiconductors. Specifically, polyaniline (PANI) stands out in food industry applications due to its advantageous reversible redox properties, electrical conductivity, and simple modification. The rising concerns about food safety and security have encouraged the development of PANI as an antioxidant, antimicrobial agent, food freshness indicator, and electronic nose. At the same time, it plays an important role in food safety control to ensure the quality of food. This study reviews the emerging applications of PANI in the food industry. It has been found that the versatile applications of PANI allow the advancement of modern active and intelligent food packaging and better food quality monitoring systems.

Hydrophobic-oleophilic gamma-irradiated modified cellulose nanocrystal/gelatin aerogel for oil absorption.

This study highlights the potential use of cellulose nanocrystals (CNCs) from kenaf fiber as a dominant phase for aerogel application. CNCs were modified with methyltrimethoxysilane (MTMS) using the sol-gel method and bound with gamma-irradiated cross-linked gelatin. The properties of the aerogel were studied using Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and water contact angle (WCA). Compression and oil absorption tests were performed to study the aerogels' mechanical and oil absorption properties. A decrease in the OH peak and improved hydrophobicity of CNCs in CNC-MTMS suggested the successful grafting of MTMS onto CNCs, as shown in the FTIR and WCA analyses. Several absorption peaks in the FTIR spectrum shifted, disappeared, or reduced, implying a formation of crosslink between gelatin molecules and hydrogen bonding between CNC and gelatin. FESEM micrographs showed well-organized pores in the gamma-irradiated aerogel, which contribute to increased compressive strength. The oil absorption test indicated that gamma-irradiated CNC-MTMS/gelatin could be a good oil absorbent. Furthermore, this aerogel showed good reusability, where only 4 % of crude oil absorption reduction occurred by the eighth cycle. The combined properties of these aerogel materials can provide good mechanical and oil absorption performance.

Dual-Layered Approach of Ovine Collagen-Gelatin/Cellulose Hybrid Biomatrix Containing Graphene Oxide-Silver Nanoparticles for Cutaneous Wound Healing: Fabrication, Physicochemical, Cytotoxicity and Antibacterial Characterisation.

Tissue engineering products have grown rapidly as an alternative solution available for chronic wound and burn treatment. However, some drawbacks include additional procedures and a lack of antibacterial properties that can impair wound healing, which are issues that need to be tackled effectively for better wound recovery. This study aimed to develop a functionalized dual-layered hybrid biomatrix composed of collagen sponge (bottom layer) to facilitate cell proliferation and adhesion and gelatin/cellulose hydrogel (outer layer) incorporated with graphene oxide and silver nanoparticles (GC-GO/AgNP) to prevent possible external infections post-implantation. The bilayer hybrid scaffold was crosslinked with 0.1% (w/v) genipin for 6 h followed by advanced freeze-drying technology. Various characterisation parameters were employed to investigate the microstructure, biodegradability, surface wettability, nanoparticles antibacterial activity, mechanical strength, and biocompatibility of the bilayer bioscaffold towards human skin cells. The bilayer bioscaffold exhibited favourable results for wound healing applications as it demonstrated good water uptake (1702.12 ± 161.11%), slow rate of biodegradation (0.13 ± 0.12 mg/h), and reasonable water vapour transmission rate (800.00 ± 65.85 gm−2 h−1) due to its porosity (84.83 ± 4.48%). The biomatrix was also found to possess hydrophobic properties (48.97 ± 3.68°), ideal for cell attachment and high mechanical strength. Moreover, the hybrid GO-AgNP promoted antibacterial properties via the disk diffusion method. Finally, biomatrix unravelled good cellular compatibility with human dermal fibroblasts (>90%). Therefore, the fabricated bilayer scaffold could be a potential candidate for skin wound healing application.

Starch/Polyaniline Biopolymer Film as Potential Intelligent Food Packaging with Colourimetric Ammonia Sensor.

The use of petroleum-based plastics in food packaging leads to various environmental impacts, while spoilage of food and misinterpretation of food-date labelling account for food insecurity; therefore, a biopolymer capable of indicating food edibility is prepared to resolve these issues. In this research, starch/polyaniline (starch/PANI) biopolymer film was synthesised and investigated as an ammonia sensor for potential application as intelligent food packaging. FT-IR and XRD were used to confirm the composition of the biopolymer films, while UV-Vis spectrometry was applied to identify the oxidation state of PANI in emeraldine form. PANI was successfully incorporated into the starch matrix, leading to better thermal stability (TGA) but decreasing the crystallinity of the matrix (DSC). The performance of the polymer-film sensor was determined through ammonia-vapour sensitivity analysis. An obvious colour change from green to blue of starch/PANI films was observed upon exposure to the ammonia vapour. Starch/PANI 0.4% is the optimum composition, having the best sensor performance with good linearity (R2 = 0.9459) and precision (RSD = 8.72%), and exhibiting excellent LOD (245 ppm). Furthermore, the starch/PANI films are only selective to ammonia. Therefore, the starch/PANI films can be potentially applied as colourimetric ammonia sensors for intelligent food packaging.

Comprehensive exploration of natural degradation of poly(lactic acid) blends in various degradation media: A review.

Poly(lactic acid) (PLA), a bio-based polyester, has been extensively investigated in the recent past owing to its excellent mechanical properties. Several studies have been conducted on PLA blends, with a focus on improving the brittleness of PLA to ensure its suitability for various applications. However, the increasing use of PLA has increased the contamination of PLA-based products in the environment because PLA remains intact even after three years at sea or in soil. This review focuses on analyzing studies that have worked on improving the degradation properties of PLA blends and studies how other additives affect degradation by considering different degradation media. Factors affecting the degradation properties, such as surface morphology, water uptake, and crystallinity of PLA blends, are highlighted. In natural, biotic, and abiotic media, water uptake plays a crucial role in determining biodegradation rates. Immiscible blends of PLA with other polymer matrices cause phase separation, increasing the water absorption. The susceptibility of PLA to hydrolytic and enzymatic degradation is high in the amorphous region because it can be easily penetrated by water. It is essential to study the morphology, water absorption, and structural properties of PLA blends to predict the biodegradation properties of PLA in the blends.

Functional Hydrophilic Membrane for Oil-Water Separation Based on Modified Bio-Based Chitosan-Gelatin.

In this study, we fabricated a modified biomaterial based on chitosan and gelatin, which is an intrinsic hydrophilic membrane for oil-water separation to clean water contamination by oil. Modification of the membrane with a non-toxic natural crosslinker, genipin, significantly enhanced the stability of the biopolymer membrane in a water-based medium towards an eco-friendly environment. The effects of various compositions of genipin-crosslinked chitosan-gelatin membrane on the rheological properties, thermal stability, and morphological structure of the membrane were investigated using a dynamic rotational rheometer, thermogravimetry analysis, and chemical composition by attenuated total reflectance spectroscopy (ATR). Modified chitosan-gelatin membrane showed completely miscible blends, as determined by field-emission scanning electron microscopy, differential scanning calorimetry, and ATR. Morphological results showed membrane with establish microstructure to further experiment as filtration product. The membranes were successfully tested for their oil-water separation efficiencies. The membrane proved to be selective and effective in separating water from an oil-water mixture. The optimum results achieved a stable microporous structure of the membrane (microfiltration) and a separation efficiency of above 98%. The membrane showed a high permeation flux, generated as high as 698 and 420 L m-2 h-1 for cooking and crude oils, respectively. Owing to its outstanding recyclability and anti-fouling performance, the membrane can be washed away easily, ensuring the reusability of the prepared membrane.

Cetyltrimethylammonium bromide-nanocrystalline cellulose (CTAB-NCC) based microemulsions for enhancement of topical delivery of curcumin.

Low bioavailability and poor water solubility have limited the utilization of curcumin in conventional dosing methods. As an alternative, microemulsions as drug carrier can improve curcumin delivery. A cetyltrimethylammonium bromide-nanocrystalline cellulose (CTAB-NCC)-based microemulsion was developed and its potential use as a topical delivery method for curcumin was investigated. The effect of microemulsion's particle size and its microstructure as well as the presence of the CTAB-NCC nanoparticle on the topical delivery of curcumin was studied. In vitro permeation studies showed higher penetration rate of curcumin from the oil-in-water type-microemulsions. The skin permeation profile of curcumin followed Higuchi release kinetics. Furthermore, use of the (CTAB-NCC)-based microemulsion enhanced curcumin accumulation in the skin and these system showed non cytotoxicity effect on L929 cell line. These results showed the potential of (CTAB-NCC)-based microemulsions as controlled-release topical systems for the delivery of curcumin and potentially other lipophilic drugs.

Physicochemical Characterization of Bilayer Hybrid Nanocellulose-Collagen as a Potential Wound Dressing.

The eminent aim for advance wound management is to provide a great impact on the quality of life. Therefore, an excellent strategy for an ideal wound dressing is being developed that eliminates certain drawbacks while promoting tissue regeneration for the prevention of bacterial invasion. The aim of this study is to develop a bilayer hybrid biomatrix of natural origin for wound dressing. The bilayer hybrid bioscaffold was fabricated by the combination of ovine tendon collagen type I and palm tree-based nanocellulose. The fabricated biomatrix was then post-cross-linked with 0.1% (w/v) genipin (GNP). The physical characteristics were evaluated based on the microstructure, pore size, porosity, and water uptake capacity followed by degradation behaviour and mechanical strength. Chemical analysis was performed using energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectrophotometry (FTIR), and X-ray diffraction (XRD). The results demonstrated a uniform interconnected porous structure with optimal pore size ranging between 90 and 140 µm, acceptable porosity (>70%), and highwater uptake capacity (>1500%). The biodegradation rate of the fabricated biomatrix was extended to 22 days. Further analysis with EDX identified the main elements of the bioscaffold, which contains carbon (C) 50.28%, nitrogen (N) 18.78%, and oxygen (O) 30.94% based on the atomic percentage. FTIR reported the functional groups of collagen type I (amide A: 3302 cm-1, amide B: 2926 cm-1, amide I: 1631 cm-1, amide II: 1547 cm-1, and amide III: 1237 cm-1) and nanocellulose (pyranose ring), thus confirming the presence of collagen and nanocellulose in the bilayer hybrid scaffold. The XRD demonstrated a smooth wavy wavelength that is consistent with the amorphous material and less crystallinity. The combination of nanocellulose with collagen demonstrated a positive effect with an increase of Young's modulus. In conclusion, the fabricated bilayer hybrid bioscaffold demonstrated optimum physicochemical and mechanical properties that are suitable for skin wound dressing.

pH-Responsive Gamma-Irradiated Poly(Acrylic Acid)-Cellulose-Nanocrystal-Reinforced Hydrogels.

A pH-sensitive poly(acrylic acid) composite hydrogel was successfully synthesized via gamma irradiation and reinforced with cellulosic materials of different sizes. Cellulose was extracted from rice husks via alkali and bleaching treatment, and an acid hydrolysis treatment was performed to extract cellulose nanocrystals (CNCs). Morphological observation of cellulose and CNCs using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed diameters of 22-123 µm and 5-16 nm, respectively. The swelling properties of the fabricated poly(acrylic acid)/cellulosic hydrogels were found to respond to changes in pH, and CNC-reinforced hydrogels performed better than cellulose-reinforced hydrogels. The highly crystalline CNC provided a greater storage modulus, hence acting as a better reinforcing material for poly(acrylic acid)-based hydrogels. SEM showed that hydrogels reinforced with the CNC nanofillers contained a homogeneous pore distribution and produced better interfacial interactions than those reinforced with the cellulose microfillers, thus performing better as hydrogels. These findings demonstrate that gamma-irradiated poly(acrylic acid) hydrogels reinforced with CNCs exhibit a better stimuli response toward pH than poly(acrylic acid) hydrogels reinforced with cellulose.

Influence of amorphous cellulose on mechanical, thermal, and hydrolytic degradation of poly(lactic acid) biocomposites.

Eco-friendly materials such as poly(lactic acid) (PLA) and cellulose are gaining considerable interest as suitable substitutes for petroleum-based plastics. Therefore, amorphous cellulose (AC) was fabricated as a new reinforcing material for PLA biocomposites by modifying a microcrystalline cellulose (MCC) structure via milling. In this study, the mechanical properties, thermal properties, and degradability of PLA were analysed to compare the effects of both MCC and AC on PLA. The tensile and impact properties improved at an optimum value with AC at 8 wt% and 4 wt% fibre loading, respectively. Notably, a scanning electron micrograph analysis revealed improved AC fibre-matrix adhesion, compared with MCC fibre-matrix adhesion, as well as excellent interaction between AC and PLA. Both MCC and AC improved the hydrolytic degradation of PLA. Moreover, the biocomposites with AC exhibited superior degradation when the incorporation of AC improved the water absorption efficiency of PLA. These findings can expand AC applications and improve sustainability.

Effects of Hybridized Organically Modified Montmorillonite and Cellulose Nanocrystals on Rheological Properties and Thermal Stability of K-Carrageenan Bio-Nanocomposite.

Herein, hybrid k-carrageenan bio-nanocomposite films were fabricated by using two types of nanofillers, organically modified montmorillonite (OMMT), and cellulose nanocrystals (CNCs). Hybrid bio-nanocomposite films were made by casting techniques employing 4 wt% of CNCs, OMMT, and hybridized CNCs/OMMT in a 1:1 ratio. The rheological and morphological properties and thermal stability of all composites were investigated using rotational rheometry, thermogravimetry analysis, differential scanning calorimetry, field emission scanning electron microscopy, and transmission electron microscopy (TEM). The results showed that the hybrid CNC/OMMT bio-nanocomposite exhibited significantly improved properties as compared to those for the bio-nanocomposites with single fillers due to the nanosize and homogenous nanofiller dispersion in the matrix. Rheological analysis of the hybrid bio-nanocomposite showed higher dynamic shear storage modulus and complex viscosity values when compared to those for the bio-nanocomposite with individual fillers. The TEM analysis of the hybridized CNC/OMMT bio-nanocomposite revealed that more particles were packed together in the CNC network, which restricted the matrix mobility. The heat resistance and thermal stability bio-nanocomposite k-carrageenan film enhanced rapidly with the addition of hybridized CNCs/OMMT to 275 °C. The hybridized CNCs/OMMT exhibited synergistic effects due to the good affinity through interfacial interactions, resulting in the improvement of the material properties.

The remarkable three-dimensional network structure of bacterial cellulose for tissue engineering applications.

Cellulose is a natural homopolymer, composed of ß-1,4- anhydro-d-glucopyranose units. Unlike plant cellulose, bacterial cellulose (BC), obtained from species belonging to the genera of Acetobacter, Rhizobium, Agrobacterium, and Sarcina through various cultivation methods and techniques, is produced in its pure form. BC is produced in the form of gel-like, never dry sheet with tremendous mechanical properties. Containing up to 99% of water, BC hydrogel is considered biocompatible thus finding robust applications in the health industry. Moreover, BC three-dimensional structure closely resembles the extracellular matrix (ECM) of living tissue. In this review, we focus on the porous BC morphology particularly suited to host oxygen and nutrients thus providing conducive environment for cell growth and proliferation. The remarkable BC porous morphology makes this biological material a promising templet for the generation of 3D tissue culture and possibly for tissue-engineered scaffolds.

Nanocrystalline cellulose decorated quantum dots based tyrosinase biosensor for phenol determination.

Novel biosensor architecture based on nanocrystalline cellulose (NCC)/CdS quantum dots (QDs) nanocomposite was developed for phenol determination. This nanocomposite was prepared with slight modification of nanocrystalline cellulose (NCC) with cationic surfactant of cetyltriammonium bromide (CTAB) and further decorated with 3-mercaptopropionic acid (3-MPA) capped CdS QDs. The nanocomposite material was then employed as scaffold for immobilization of tyrosinase enzyme (Tyr). The electrocatalytic response of Tyr/CTAB-NCC/QDs nanocomposite towards phenol was evaluated using differential pulse voltammetry (DPV). The current response obtained is proportional to the concentration of phenol which attributed to the reduction of o-quinone produced at the surface of the modified electrode. Under the optimal conditions, the biosensor exhibits good linearity towards phenol in the concentration range of 5-40 µM (R2 = 0.9904) with sensitivity and limit of detection (LOD) of 0.078 µA/µM and 0.082 µM, respectively.

Application of polymethylmethacrylate-grafted cellulose as reinforcement for compatibilised polylactic acid/natural rubber blends.

In this study, modified agave cellulose fibre combined by graft copolymerisation with methylmethacrylate was tested as a potential reinforcement for polylactic acid (PLA)-natural rubber/liquid natural rubber blends. Mechanical, morphological, thermal, wetting, and biodegradation characterisations were performed to assess the influence of cellulose-graft-polymethylmethacrylate (cell-g-PMMA) content on the properties of biocomposites. The addition of cell-g-PMMA improved the mechanical properties of the composites because of the chemical interaction between PLA and PMMA. Thermal stability decreased slightly upon cell-g-PMMA addition because of the low thermal stability of PMMA. A soil burial test revealed that the degradation of composites decreased with an increase in the cell-g-PMMA content. However, the weight loss after burial, which directly affected the water absorption capacity, was still higher for the cell-g-PMMA composites than for the polymer alone.

Electrochemical performance of poly(3, 4-ethylenedioxythipohene)/nanocrystalline cellulose (PEDOT/NCC) film for supercapacitor.

Supercapacitor electrode based on conducting polymer of poly (3,4-ethylenedioxythipohene) (PEDOT) doped with nanocrystalline cellulose (NCC) films were prepared via electrochemical polymerization technique. Different applied potential, concentration and deposition time were varied to study the effect of electropolymerization potential, NCC concentration and deposition time on the formation of PEDOT/NCC film. The formation of electrochemically polymerized PEDOT/NCC composite was successfully proven with field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR) techniques where the composites exhibited an interconnected network-like surface morphology. PEDOT/NCC deposited at 1.2 V in 1 mg/ml of NCC for 15 min showed the highest specific capacitance of 117.02 F/g at 100 mV/s with energy density and power density of 11.44 Wh/kg and 99.85 W/kg, respectively at the current density of 0.2 A/g. The incorporation of NCC into PEDOT revealed a lower resistance of charge transfers and improves the cycling stability by retaining 86% of capacitance after 1000 cycles.

Synergistic Effect of Hybridized Cellulose Nanocrystals and Organically Modified Montmorillonite on κ-Carrageenan Bionanocomposites.

The synergistic effect of using κ-carrageenan bionanocomposites with the hybridization of cellulose nanocrystals (CNCs) and organically modified montmorillonite (OMMT) reinforcements was studied. The effects of different reinforcements and filler contents were evaluated through mechanical testing, and morphological and water uptake properties. The tensile strength and Young's modulus of both bionanocomposites increased with filler loading and optimized at 4%. OMMT incorporation into the κ-carrageenan/CNCs bionanocomposites resulted in further mechanical property improvement with an optimum ratio of 1:1 (CNCs:OMMT) while maintaining high film transparency. X-ray diffraction and morphological analyses revealed that intercalation occurred between the κ-carrageenan bionanocomposite matrix and OMMT. The water uptake of the κ-carrageenan bionanocomposites was significantly reduced by the addition of both CNCs and OMMT. The enhancements in the mechanical properties and performance of the hybrid bionanocomposite indicate compatibility among the reinforcement, biopolymer, and well-dispersed nanoparticles. This renders the hybrid CNC/OMMT/κ-carrageenan nanocomposites extremely promising for food packaging applications.

Gamma Irradiation-Assisted Synthesis of Cellulose Nanocrystal-Reinforced Gelatin Hydrogels.

Herein, we describe the use of gamma irradiation to prepare hydrogels comprising α-cellulose and cellulose nanocrystal (CNC)-reinforced gelatin in the absence of crosslinking agents. In this study, cellulose was extracted from rice husks by an alkali and bleaching treatment followed by acid hydrolysis to produce CNC. A semi-interpenetrating network (semi-IPN) of hydrogels was developed by the miscibility between gelatin and cellulosic materials. Compared to those prepared from α-cellulose, hydrogels prepared by dispersion of CNCs exhibited remarkably enhanced stiffness and swelling properties, which was ascribed to the uniform distribution of CNCs and their increased crystallinity. Improved pore structure, arrangement, and rigidity of CNC-reinforced gelatin hydrogels, which induced the swelling mechanism resulting in higher and faster water uptake was observed with a scanning electron microscope (SEM), compared to cellulose-reinforced gelatin hydrogels. Moreover, in vitro drug profiling demonstrated that CNC/gelatin hydrogels exhibit good drug loading/release behavior and are thus suitable for use in drug-delivery applications.

Synthesis and Swelling Behavior of pH-Sensitive Semi-IPN Superabsorbent Hydrogels Based on Poly(acrylic acid) Reinforced with Cellulose Nanocrystals.

pH-sensitive poly(acrylic acid) (PAA) hydrogel reinforced with cellulose nanocrystals (CNC) was prepared. Acrylic acid (AA) was subjected to chemical cross-linking using the cross-linking agent MBA (N,N-methylenebisacrylamide) with CNC entrapped in the PAA matrix. The quantity of CNC was varied between 0, 5, 10, 15, 20, and 25 wt %. X-ray diffraction (XRD) data showed an increase in crystallinity with the addition of CNC, while rheology tests demonstrated a significant increase in the storage modulus of the hydrogel with an increase in CNC content. It was found that the hydrogel reached maximum swelling at pH 7. The potential of the resulting hydrogels to act as drug carriers was then evaluated by means of the drug encapsulation efficiency test using theophylline as a model drug. It was observed that 15% CNC/PAA hydrogel showed the potential to be used as drug carrier system.

Hydrophobic kenaf nanocrystalline cellulose for the binding of curcumin.

Nanocrystalline cellulose (NCC) extracted from lignocellulosic materials has been actively investigated as a drug delivery excipients due to its large surface area, high aspect ratio, and biodegradability. In this study, the hydrophobically modified NCC was used as a drug delivery excipient of hydrophobic drug curcumin. The modification of NCC with a cationic surfactant, cetyl trimethylammonium bromide (CTAB) was used to modulate the loading of hydrophobic drugs that would not normally bind to NCC. The FTIR, Elemental analysis, XRD, TGA, and TEM were used to confirm the modification of NCC with CTAB. The effect of concentration of CTAB on the binding efficiency of hydrophobic drug curcumin was investigated. The amounts of curcumin bound onto the CTAB-NCC nanoparticles were analyzed by UV-vis Spectrophotometric. The result showed that the modified CTAB-NCC bound a significant amount of curcumin, in a range from 80% to 96% curcumin added. Nevertheless, at higher concentration of CTAB resulted in lower binding efficiency.

Hydrophobic modification of cellulose isolated from Agave angustifolia fibre by graft copolymerisation using methyl methacrylate.

Graft copolymerisation of methyl methacrylate (MMA) onto Agave angustifolia was conducted with ceric ammonium nitrate (CAN) as the redox initiator. The maximum grafting efficiency was observed at CAN and MMA concentrations of 0.91 × 10(-3) and 5.63 × 10(-2)M, respectively, at 45°C for 3h reaction time. Four characteristic peaks at 2995, 1738, 1440, and 845 cm(-1), attributed to PMMA, were found in the IR spectrum of grafted cellulose. The crystallinity index dropped from 0.74 to 0.46, while the thermal stability improved upon grafting. The water contact angle increased with grafting yield, indicating increased hydrophobicity of cellulose. SEM images showed the grafted cellulose to be enlarged and rougher. The changes in the physical nature of PMMA-grafted cellulose can be attributed to the PMMA grafting in the amorphous regions of cellulose, causing it to expand at the expense of the crystalline component.