Green tea polyphenols have been reported to possess many biological properties. Despite the many potential benefits of green tea extracts, their sensitivity to high temperature, pH and oxygen is a major disadvantage hindering their effective utilization in the food industry. Green tea leaves from the Cameron Highlands Malaysia were extracted using supercritical fluid extraction (SFE). To improve the stability, green tea extracts were encapsulated by spray-drying using different carrier materials including maltodextrin (MD), gum arabic (GA) and chitosan (CTS) and their combinations at different ratios. Encapsulation efficiency, total phenolic content and antioxidant capacity were determined and were found to be in the range of 71.41%-88.04%, 19.32-24.90 (g GAE/100 g), and 29.52%-38.05% respectively. Further analysis of moisture content, water activity, hygroscopicity, bulk density and mean particles size distribution of the microparticles were carried out and the results ranged from; 2.31%-5.11%, 0.28-0.36, 3.22%-4.71%, 0.22-0.28 g/cm³ and 40.43-225.64 µm respectively. The ability of the microparticles to swell in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was determined as 142.00%-188.63% and 207.55%-231.77%, respectively. Release of catechin polyphenol from microparticles in SIF was higher comparable to that of SGF. Storage stability of encapsulated catechin extracts under different temperature conditions was remarkably improved compared to non-encapsulated extract powder. This study showed that total catechin, total phenolic content (TPC) and antioxidant activity did not decrease significantly (p ≥ 0.05) under 4 °C storage conditions. The half-life study results were in the range of 35-60, 34-65 and 231-288 weeks at storage temperatures of 40 °C, 25 °C and 4 °C respectively, therefore, for improved shelf-life stability we recommend that microparticles should be stored at temperatures below 25 °C.
Bone fracture, being mainly caused by mechanical stress, requires special and quick attention for a rapid healing. The study presented here aims at formulating nanoparticulate system to overcome the solubility issues of lovastatin. The lovastatin nanoparticles were successfully prepared by ionotropic gelation method using chitosan and tri-polyphosphate as polymers. Thus prepared nanoparticles were found to be smooth and spherical with average particle size of 87 nm and encapsulation efficiency of 86.5%. The in-vitro drug release was found to be almost 89.6% in the first 360 minutes. Artificial fracture was produced in female Wistar rats at right leg using fracture apparatus. After administration of lovastatin nanoparticles or saline solution, the respective groups were observed for various parameters. The X-ray imaging showed that lovastatin accelerated bone healing, compared to control. The growth of animals was not hampered by lovastatin by any means. The radiographic examination confirmed a role of lovastatin in increasing bone density. The histological study showed the broken, proliferated and discontinued trabecullae in the control, while at the same time point, the normal, thick, continuous and connected trabecullae were observed in animals administered with lovastatin nanoparticles. The biomechanical studies showed high breaking resilience and minimum bone brittleness in animals injected with lovastatin nanoparticles. Considering these observations we state that lovastatin helps in rapid bone healing after fracture via increasing the bone density.
Blends of poly (1, 8-octanediol citrate) (POC) and chitosan (CS) were prepared through solution casting technique. Films with different component fractions (POC/CS: 100/0, 90/10, 80/20, 70/30, 60/40, and 0/100) were successfully prepared and characterized for their mechanical, thermal, structural and morphological properties as well as biocompatibility. The incorporation of CS to POC significantly increased tensile strength and elastic modulus and presented limited influences on pH variation which is important to the biocompatibility of biomaterial implants. The assessment of surface topography indicated that blending could enhance and control the surface roughness of the pure films. POC/CS blends well-supported human dermal fibroblast cells attachment and proliferation, and thus can be used for a range of tissue engineering applications.
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.
In this study, the combination of novel valinomycin doped chitosan-graphene oxide (C-GO-V) thin film and surface plasmon resonance (SPR) system for potassium ion (K+) detection has been developed. The novel C-GO-V thin film was deposited on the gold surface using spin coating technique. The system was used to monitor SPR signal for K+ in solution with and without C-GO-V thin film. The K+ can be detected by measuring the SPR signal when C-GO-V thin film is exposed to K+ in solution. The sensor produces a linear response for K+ ion up to 100ppm with sensitivity and detection limit of 0.00948°ppm-1 and 0.001ppm, respectively. These results indicate that the C-GO-V film is high potential as a sensor element for K+ that has been proved by the SPR measurement.
Chitin, being the second most abundant biopolymer after cellulose, has been gaining popularity since its initial discovery by Braconot in 1811. However, fundamental knowledge and literature on chitin and its derivatives from insects are difficult to obtain. The most common and sought-after sources of chitin are shellfish (especially crustaceans) and other aquatic invertebrates. The amount of shellfish available is obviously restricted by the amount of food waste that is allowed; hence, it is a limited resource. Therefore, insects are the best choices since, out of 1.3 million species in the world, 900,000 are insects, making them the most abundant species in the world. In this review, a total of 82 samples from shellfish-crustaceans and mollusks (n = 46), insects (n = 23), and others (n = 13)-have been collected and studied for their chemical extraction of chitin and its derivatives. The aim of this paper is to review the extraction method of chitin and chitosan for a comparison of the optimal demineralization and deproteinization processes, with a consideration of insects as alternative sources of chitin. The methods employed in this review are based on comprehensive bibliographic research. Based on previous data, the chitin and chitosan contents of insects in past studies favorably compare and compete with those of commercial chitin and chitosan-for example, 45% in Bombyx eri, 36.6% in Periostracum cicadae (cicada sloughs), and 26.2% in Chyrysomya megacephala. Therefore, according to the data reported by previous researchers, demonstrating comparable yield values to those of crustacean chitin and the great interest in insects as alternative sources, efforts towards comprehensive knowledge in this field are relevant.
In this paper, the newly explored TiO(2)-Chitosan/Glass was suggested as a promising alternative material to conventional means of wastewater treatment. Characterization of TiO(2)-Chitosan/Glass photocatalyst was studied with SEM-EDX, XRD, and Fourier transform infrared spectroscopy (FTIR) analysis. The combination effect of photodegradation-adsorption process for the removal of methyl orange (MO), an acid dye of the monoazo series occur promisingly when four layers of TiO(2)-Chitosan/Glass photocatalyst was used for MO removal. Approximately, 87.0% of total MO removal was achieved. The reactive -NH(2), -OH, and metal oxide contents in the prepared photocatalyst responsible for the photodegradation-adsorption effect were confirmed by FTIR study. Similarly, MO removal behavior was well supported by SEM-EDX and XRD analysis. Significant dependence of MO removal on the TiO(2)-Chitosan loading can be explained in terms of relationship between quantum yield of photocatalytic reactions and photocatalyst structure/activity. Hence, the research work done thus far suggests a new method, having both the advantages of photodegradation-adsorption process in the abatement of various wastewater pollutants.
Silver and copper nanoparticles were produced by chemical reduction of their respective nitrates by ascorbic acid in the presence of chitosan using microwave heating. Particle size was shown to increase by increasing the concentration of nitrate and reducing the chitosan concentration. Surface zeta potentials were positive for all nanoparticles produced and these varied from 27.8 to 33.8 mV. Antibacterial activities of Ag, Cu, mixtures of Ag and Cu, and Ag/Cu bimetallic nanoparticles were tested using Bacillus subtilis and Escherichia coli. Of the two, B. subtilis proved more susceptible under all conditions investigated. Silver nanoparticles displayed higher activity than copper nanoparticles and mixtures of nanoparticles of the same mean particle size. However when compared on an equal concentration basis Cu nanoparticles proved more lethal to the bacteria due to a higher surface area. The highest antibacterial activity was obtained with bimetallic Ag/Cu nanoparticles with minimum inhibitory concentrations (MIC) of 0.054 and 0.076 mg/L against B. subtilis and E. coli, respectively.
To investigate the antifungal activity of conventional chitosan and chitosan-loaded nanoemulsions against anthracnose caused by Colletotrichum spp. isolated from different tropical fruits.
Many researchers have focused chitosan as a source of potential bioactive material during the past few decades. However, chitosan has several drawbacks to be utilised in biological applications, including poor solubility under physiological conditions. Therefore, a new interest has recently emerged on partially hydrolysed chitosan, chitosan oligosaccharides (COS). In this study, degradation of chitosan was performed by Cellulase from Trichoderma reesei® 1.5L and Response Surface Methodology (RSM) were employed to optimize the hydrolysis temperature, pH, enzyme concentration and substrate concentration. Optimization of cellulase T. reesei® using central composite design (CCD) was to obtain optimum parameters and all the factors showed significant effects (p˂0.05). The maximum response, Celluclast® activity (1.268 U) was obtained by assaying the process at 49.79oC, pH 4.5, 3% (v/w) of enzyme concentration and 25% (w/v) concentration of chitosan for 24 hours.
Chitosan-polyethyleneimine with calcium chloride as ionic cross-linker (CsPC) was synthesized as a new kind of adsorbent using a simple, green and cost-effective technique. The adsorption properties of the adsorbent for Acid Red 88 (AR88) dye, as a model analyte, were investigated in a batch system as the function of solution pH (pH 3-12), initial AR88 concentration (50-500 mg L-1), contact time (0-24 h), and temperature (30-50 °C). Results showed that the adsorption process obeyed the pseudo-first order kinetic model and the adsorption rate was governed by both intra-particle and liquid-film mechanism. Equilibrium data were well correlated with the Freundlich isotherm model, with the calculated maximum adsorption capacity (qm) of 1000 mg g-1 at 30 °C. The findings underlined CsPC to be an effective and efficient adsorbent, which can be easily synthesized via one-step process with promising prospects for the removal of AR88 or any other similar dyes from the aqueous solutions.
Antibacterial activity of zinc oxide (ZnO) nanoparticles have received significant interest, particularly by the implementation of nanotechnology to synthesize particles in nanometer region. ZnO nanoparticles were successfully synthesized through microwave heating by using chitosan as a stabilizing agent and characterized by UV-vis, FTIR, XRD and FESEM-EDX. The aim of the present study is to determine the antibacterial activity of ZnO nanoparticles against Gram-positive bacterium Staphylococcus aureus (S. aureus) and Gram-negative bacterium Escherichia coli (E. coli). The antibacterial effect of ZnO nanoparticles was investigated for the inhibition zone and inactivation of cell growth. The absorption of ZnO nanoparticles was found to be around 360 nm. FTIR results showed the stretching mode of ZnO nanoparticles at 475 cm-1 of the absorption band. EDX results indicated that ZnO nanoparticles have been successfully formed with an atomic percentage of zinc and oxygen at 23.61 and 46.57% respectively. X-ray diffraction result was confirmed the single-phase formation of ZnO nanoparticles and the particle sizes were observed to be around 50 to 130 nm. The results showed that ZnO nanoparticles have displayed inhibition zone of 16 and 13 mm against S. aureus and E. coli respectively. Gram-negative bacteria seemed to be more resistant to ZnO nanoparticles than Gram-positive bacteria.
Gallocynin immobilized in chitosan membrane has been studied as a sensor element of an optical sensor for lead using a flowing system. By using this set up, lead in solution has been determined in the concentration range from 1.0x10(-1) to 1.0x10(3) ppm with a detection limit of 0.075 ppm. The standard deviation of the method for the repeatability of lead detection at a concentration of 100 ppm was found to be 2.10%. The response of the sensor was reproducible and can be regenerated by using acidified saturated KNO(3) solution. Interference from foreign ions was also studied at 1:1 mole ratio of Pb(II):foreign ions.
Natural polymer guar gum has one of the highest viscosities in water solution and hence, these are significantly used in pharmaceutical applications. Guar gum inter-connected micelles as a new carrier has been developed for poor water soluble rifampicin drug. The hydrogel inter-connected micelle core was formulated as a hydrophilic inner and hydrophobic outer core by using guar gum/chitosan/polycaprolactone and the carrier interaction with rifampicin was confirmed by FT-IR. The morphological observations were carried out through TEM, SEM and AFM analysis. The encapsulation efficiency and in-vitro drug release behavior of prepared hydrogel based micelle system was analyzed by UV-vis spectrometry. The anti-bacterial activity against K. pneumoniae and S. aureus was studied by observing their ruptured surface by SEM. The cytotoxicity study reveals that the pure polymeric system has no toxic effect whereas drug loaded ones showed superior activity against THP-1 cells. From the cell apoptosis analyses, the apoptosis was carried out in a time dependent manner. The cell uptake behavior was also observed in THP-1 cells which indicate that the hydrogel based micelle system is an excellent material for the mucoadhesive on intracellular alveolar macrophage treatment.
The potential of ultrasonication-driven molecular self-assembly of whey protein isolate (WPI) with chitosan (CS)/chitooligosaccharide (COS) to stabilize Pickering emulsions was examined, based on CS/COS ligands-induced partial unfolding in remodeling the Pickering particles features. Multi-spectral analysis suggested obvious changes in conformational structures of WPI due to interaction with CS/COS, with significantly higher unfolding degrees of WPI induced by COS. Non-covalent interactions were identified as the major forces for WPI-CS/COS conjugates. Ultrasonication enhanced electrostatic interaction between CS's -NH3 groups and WPI's -COO- groups which improved emulsification activity and storability of WPI-COS stabilized Pickering emulsion. This was attributed to increased surface hydrophobicity and decreased particle size compared to WPI-CS associated with differential unfolding degrees induced by different saccharide ligands. CLSM and SEM consistently observed smaller emulsion droplets in WPI-COS complexes than WPI-CS/COS particles tightly adsorbed at the oil-water interface. The electrostatic self-assembly of WPI with CS/COS greatly enhanced the encapsulation efficiency of quercetin than those stabilized by WPI alone and ultrasound further improved encapsulation efficiency. This corresponded well with the quantitative affinity parameters between quercetin and WPI-CS/COS complexes. This investigation revealed the great potential of glycan ligands-induced conformational transitions of extrinsic physical disruption in tuning Pickering particle features.
Pristine chitosan beads were modified with sulfur (S)-containing functional groups to produce thiolated chitosan beads (ETB), thereby increasing S donor ligands and crosslinks. The effect of temperature, heating time, carbon disulfide (CS2)/chitosan ratio, and pH on total S content of ETB was examined using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The total S content of ETB increased with increasing CS2/chitosan ratio and decreased with decreasing pH and increasing temperature (>60 °C) and heating time (at 60 °C). Spectroscopic analyses revealed the presence of thiol (-SH)/thione, disulfide (-S-S-), and sulfonate groups in ETB. The thiolation mechanism involves decomposition of dithiocarbamate groups, thereby forming thiourea crosslinks and trithiocarbonate, resulting in -SH oxidation to produce -S-S- crosslinks. The partially formed ETB crosslinks contribute to its acid stability and are thermodynamically feasible in adsorbing Cd and Cu. The S-containing functional groups added to chitinous wastes act as sorbents for metal remediation from acidic environments.
Acetaminophen (Ace) is a trace pollutant widely found in sewage treatment plant (STP) wastewater. We test the feasibility of coconut shell waste, a low cost adsorbent from coconut industry, for removing Ace from synthetic solution in a fixed-bed column adsorption. To enhance its performance, the surface of granular activated carbon (GAC) was pre-treated with NaOH, HNO3, ozone, and/or chitosan respectively. The results show that the chemical modification of the GAC's surface with various chemicals has enhanced its Ace removal during the column operations. Among the modified adsorbents, the ozone-treated GAC stands out for the highest Ace adsorption capacity (38.2 mg/g) under the following conditions: 40 mg/L of Ace concentration, 2 mL/min of flow rate, 45 cm of bed depth. Both the Thomas and the Yoon-Nelson models are applicable to simulate the experimental results of the column operations with their adsorption capacities: ozone-treated GAC (20.88 mg/g) > chitosan-coated GAC (16.67 mg/g) > HNO3-treated GAC (11.09 mg/g) > NaOH-treated GAC (7.57 mg/g) > as-received GAC (2.84 mg/g). This suggests that the ozone-treated GAC is promising and suitable for Ace removal in a fixed-bed reactor.
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.
Herein, the polymer nanomatrix of chitosan/SiO2 (CHI/n-SiO2) was enriched with a π-π electron donor-acceptor system using diaromatic rings of benzil (BEZ) assisted via a hydrothermal process to obtain an effective adsorbent of chitosan-benzil/SiO2 (CHI-BEZ/n-SiO2). The polymer nanomatrix (CHI/n-SiO2) and the resulting adsorbent (CHI-BEZ/n-SiO2) were applied to remove the anionic acid red 88 (AR88) dye from aqueous media in a comparative mode. Box-Behnken design (BBD) was adopted to optimize AR88 adsorption onto CHI/n-SiO2 and CHI-BEZ/n-SiO2 with respect to variables that influence AR88 adsorption (adsorbent dose: 0.02-0.1 g/100 mL; pH: 4-10; and time: 10-90). The adsorption studies at equilibrium were conducted with a variety of initial AR88 dye concentrations (20-200 mg/L). The adsorption isotherm results reveal that the AR88 adsorption by CHI/n-SiO2 and CHI-BEZ/n-SiO2 are described by the Langmuir model. The kinetic adsorption profiles of AR88 with CHI/n-SiO2 and CHI-BEZ/n-SiO2 reveal that the pseudo-first-order model provides the best fit results. Interestingly, CHI-BEZ/n-SiO2 has a high adsorption capacity (261.2 mg/g), which exceeds the adsorption capacity of CHI/n-SiO2 (215.1 mg/g) that relates to the surface effects of SiO2 and the functionalization of chitosan with BEZ. These findings show that CHI-BEZ/n-SiO2 represents a highly efficient adsorbent for the removal of harmful pollutants from water, which outperforming the CHI/n-SiO2 system.
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.