pH Of Chitosan Solution Research Articles

Development of chitosan/sodium carboxymethyl cellulose-based polyelectrolyte complex of dexamethasone for treatment of anterior uveitis

Anterior uveitis is one of the most prevalent forms of ocular inflammation caused by infections, trauma, and other idiopathic conditions if not treated properly, it can cause complete blindness. Therefore, this study aimed to formulate and evaluate dexamethasone sodium phosphate (DSP) loaded polyelectrolyte complex (PEC) nanoparticles (NPs) for the treatment of anterior uveitis. DSP-loaded PEC-NPs were formed through complex coacervation by mixing low molecular weight chitosan and the anionic polymer carboxy methyl cellulose (CMC). The formulations were optimized using Box-Behnken design and evaluated the effect of independent variables: Chitosan concentration, CMC concentration, and pH of chitosan solution on the dependent variables: particle size (PS), Polydispersity Index (PDI), pH of the formulation, and % entrapment efficacy (%EE). The PS, PDI, zeta potential, and pH of the optimized formulation were found 451 ± 82.0995 nm, 0.3807 ± 0.1862, +20.33 ± 1.04 mV and 6.8367 ± 0.0737 respectively. The %EE and drug loading of formulation were 61.66 ± 4.2914% and 21.442 ± 1.814% respectively.In vitrodrug release studies of optimized formulation showed the prolonged release up to 12 h whereas, the marketed formulation showed the burst release 85.625 ± 4.3062% in 1 h and 98.1462 ± 3.0921% at 6 h, respectively. Fourier transform infrared studies suggested the effective incorporation of the drug into the PEC-NPs formulation whereas differential scanning calorimetry and x-ray diffraction studies showed the amorphized nature of the drug in the formulation. Transmission electron microscopy study showed self-assembled, nearly spherical, core-shell nanostructures. The corneal permeation study showed higher permeation of the drug from PEC-NPs compared to the marketed formulation. Hen's Eggs test-Chorioallantoic Membrane test of the optimized formulation revealed non-irritant and safe for ocular administration. Therefore, DSP-loaded PEC-NPs are an effective substitute for conventional eye drops due to their ability to increase bioavailability through longer precorneal retention duration and sustained drug release.

Encapsulation of Pomelo Peel Essential oil (Citrus maxima) Using the Alginate/Chitosan complex

Objective: This study aimed to determine appropriate parameters for encapsulating pomelo peel essential oil (Citrus maxima) using the alginate/chitosan complex. Methods: The investigated parameters included the concentration of sodium alginate solution (2 ‒ 3.5% w/v based on the volume of mixture), the concentration of pomelo essential oil (20 ‒ 40% w/w based on dry matter of wall marerials), the concentration of Tween 80 (0 ‒ 20% w/w based on dry matter of wall marerials), the concentration of CaCl2 solution (0.5 ‒ 3.5% w/v based on the volume of mixture), time (10 min – 20 min) and speed of emulsion homogenization (489-4402 × g), the concentration of chitosan solution (0.5 ‒ 2% w/v based on the volume of mixture), and pH of chitosan solution (4 ‒ 6). Results: The results showed encapsulation yield (EY%) and encapsulation efficiency (EE%) of 91.64% and 85.18%, respectively, when using the concentration of sodium alginate solution as 3% (w/v based on the volume of mixture), the concentration of essential oil as 30% (w/w based on dry matter of wall marerials), the concentration of Tween 80 as 15% (w/w based on dry matter of wall marerials), the concentration of CaCl2 solution as 1.5% (w/v based on the volume of mixture), homogenization time as 10 min and homogenization speed as 4402 × g, the concentration of chitosan as 2% (w/v based on the volume of mixture) and pH of Chitosan solution as 5. Conclusion: The alginate/chitosan complex was proven effective in encapsulating pomelo essential oil (Citrus maxima) on a laboratory scale. The resulting encapsulated particles had a relatively uniform size and a high ability to retain essential oils in the core of the particles. Further studies should be conducted to elucidate the mechanism of the encapsulation process and to additionally evaluate the physical and chemical properties of the encapsulated particles.

Synthesis, characterization and evaluation of anti-arthritic and anti-inflammatory potential of curcumin loaded chitosan nanoparticles

Curcumin is a phytochemical isolated from the dried rhizome of Curcuma longa L. family Zingiberaceae which possesses versatile biological activities and has hydrophobic properties. The current study was conducted to fabricate, and optimize curcumin loaded chitosan and Sodium tripolyphosphate (STPP) nanoparticles (NPs) to improve the bioavailability of curcumin. NPs were fabricated employing the Ionic gelation method. Four formulations were developed based on the selected variables like STPP and chitosan concentration, rotations per minute (rpm), temperature, and pH of chitosan solution. NPs were characterized for morphology, drug-polymer compatibility, yield, particle size, encapsulation efficiency, release behavior, anti-inflammatory and anti-arthritic activity compared to curcumin and standard drug. Fourier transform infrared spectroscopy (FTIR) shows nanoparticle compatibility. The maximum yield was 60%. Entrapment efficiency ranged from 45 to 65%. Curcumin NPs and standard drug 600 µg/ml shows 59% and 70% anti-inflammatory activity by HRB membrane stabilization method respectively which are greater than curcumin alone whereas anti-arthritic activity by protein denaturation method which is also comparable to standard drug and greater than curcumin was 66 and 70% respectively. Statistical analysis shows the mean significant difference at p ≤ 0.05. The study concluded that curcumin-loaded chitosan and STPP NPs formulated successfully by the Ionic gelation method, which increased curcumin absorption leading to a reduced dosing rate and improved patient compliance.

Skin targeting by chitosan/hyaluronate hybrid nanoparticles for the management of irritant contact dermatitis: In vivo therapeutic efficiency in mouse-ear dermatitis model

Irritant contact dermatitis (ICD) is an inflammatory skin condition characterized by severe eczematous lesions. Nanoparticulate drug delivery is the most predominant way to improve dermal penetration and have gained remarkable recognition for targeted delivery of therapeutic payload and reduced off-target effects. Therefore, the current work aimed to fabricate polyelectrolyte complex nanoparticles (PENPs) containing two natural biodegradable polymers namely; chitosan (CS) and hyaluronic acid (HA) to deliver the non steroidal anti-inflammatory drug etoricoxib (ETX) to the deeper skin layers to alleviate any systemic toxicity and improve its therapeutic efficacy against ICD. ETX loaded-PENPs were prepared and optimized utilizing three independent variables; CS: HA mass ratio, chitosan solution pH and molecular weight of chitosan. Following the various physicochemical optimizations, the optimum ETX-loaded PENPs formulation (N1 0.15 %) exhibited spherical nature with an average diameter of 267.9 ± 9.4 nm, Polydispersity index of 0.366 ± 0.02, and positive zeta potential (+32.9 ± 0.47 mV). The drug was successfully entrapped and the entrapment efficiency reached 95 ± 0.2 %. N1 0.15 % formula showed efficient dermal targeting by significantly enhanced percentage of ETX permeated and retained in the various skin layers in comparison to ETX conventional gel during the ex-vivo skin permeation experiments. Furthermore, N1 0.15 % exhibited superior anti-inflammatory properties in vivo compared to ETX conventional gel in dithranol induced mice ear dermatitis. Conclusively, ETX-loaded PENPs could be a promising therapeutic approach for effecient management of ICD.

Preparation and characterization of tea polyphenols-chitosan-based nanoparticles and their application in starch films

Green composite starch films were prepared using tea polyphenols-chitosan-based nanoparticles as active agent and nanocellulose as strength agent, which showed good mechanical and antioxidant activities and is a candidate for food packaging in this work. Here, chitosan-based nanoparticles containing tea polyphenols (CNTP) were prepared by the ionic gel method. The best utilization of tea polyphenols could be achieved when the mass ratio of tea polyphenols to sodium tripolyphosphate was 3:1, the concentration of tea polyphenols was 0.01 g/mL, and the pH of chitosan solution was 4. Uniform and stable CNTP with a particle size of approximately 200 nm was prepared. CNTP release rates were 45.9% after 6 h, showing the ability to release slowly. Using starch as the substrate, nanocellulose as the enhancer, and tea polyphenols as the antioxidant and antibacterial agent, an active film was prepared that demonstrated improved transparency, mechanical properties, and antioxidant and antibacterial activity. Its transmittance reached 83.9%, and the tensile strength was 33.4 MPa. The scavenging efficiency of 2,2-diphenyl-1-picrylhydrazyl (DPPH) by the composite film was 42%, and the OD value of the composite film was 0.9348. The results showed that CNTP can prolong the release period and activity of tea polyphenols, and the composite film with CNTP had antibacterial and antioxidant activities to prolong the shelf life of food.

Ionic gelation of chitosan with sodium tripolyphosphate using a novel combined nebulizer and falling film system

AbstractNanoparticle technology has made an essential contribution to the pharmaceutical industry and has received considerable attention in comparison with the other domains. In the present study, ionic gelation via a novel combined system of nebulizer and falling film (IG‐NFF) has been proposed. The purpose of the design of this system is to increase the contact surface between the chitosan and sodium tripolyphosphate (STPP) for the preparation of monodisperse and spherical chitosan nanoparticles, because in both nebulizer and falling film systems, the surface‐to‐volume ratio of liquid increases. The formation of these nanoparticles is based on ionic interactions between the negatively charged phosphate groups in the STPP and positively charged amine groups on the chitosan. In this research, the effects of chitosan concentration, STPP concentration, the distance of the nebulizer from the inclined plate, gas to liquid flow rate ratio, and the initial chitosan solution pH on the z‐average size, polydispersity index (PDI), and morphology of nanoparticles formed by IG‐NFF were studied. The results showed that the IG‐NFF process has the ability to produce spherical particles with highly uniform sizes. The mean size of obtained chitosan nanoparticles was in the range of 80–320 nm, and the PDI value ranged from 0.08–0.30.

Optimization and characterization of lemon essential oil entrapped from chitosan/cellulose nanocrystals microcapsules

AbstractThe purpose of this study is to prepare lemon essential oil (LEO) microcapsules by ionic gelation method using chitosan (CS) and cellulose nanocrystals (CNC) as the wall material. The influence of the concentration of CS and CNC and the pH of CS solution on the encapsulation efficiency (EE) of microcapsules was studied. Taking the EE as an indicator, and according to the single‐factor test results, a three‐factor three‐level response surface methodology was designed. The best process conditions of CS/CNC‐LEO microcapsules to get the maximum EE of 89.98% were as follows: pH of CS was 3.44, and the concentration of CS, CNC were 2, 3.52 g/L. The microcapsules prepared under these conditions were smooth and rounded spherical. The diameters of unembedded and embedded LEO microcapsules ranged from 541.2–732.9 to 1014.5–1528.7 nm, respectively. Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis were used to analyze the characteristics of the microcapsules. There were two periods in vitro release studies of CS/CNC‐LEO microcapsules: sudden release and slow release of essential oils.

Clarithromycin Loaded Chitosan Nanoparticles: Development and Characterization

Background:: Chitosan nanoparticles have been extensively studied and used due to their well-recognized applicability in various fields. Chitosan, a natural polysaccharide polymer, is extensively used in pharmaceuticals to deliver a wide variety of therapeutic agents. Chitosan is a biocompatible and biodegradable mucoadhesive polymer that has been extensively used in the preparation of multi particles, particularly nano- and microparticles. Objective:: The main aim of the present study was to optimize the conditions for the preparation of chitosan nanoparticles to get optimal particle size, with optimal zeta potential and narrow polydispersity index and anti-bacterial activity. Methods:: Include the ionic gelation technique for chitosan nanoparticle preparation. The influence of formulation parameters and process parameters on the chitosan nanoparticles were investigated. Besides, the suspension stability of the prepared nanoparticles was also assessed on storage at 4°C. Results: The formulation and process parameters showed a significant effect on the physicochemical and morphological characteristics of the chitosan nanoparticles. The chitosan nanoparticles prepared under optimum conditions (chitosan concentration of 0.5% w/v, CS: TPP mass ratio of 1:3, initial pH of chitosan solution of 4.5, stirred at 750 rpm for 30 min) had shown a mean particle size of ~326.8±15 nm, zeta potential of +28.2 ± 0.5 mV, and PDI of 0.21 ± 0.02. The encapsulation of the clarithromycin slightly increased the polydispersity index, but the zeta potential of the unloaded nanoparticles was not affected while the particle size increased. Under optimum conditions, clarithromycin encapsulation efficiency into nanoparticles was found to be 70%. Additionally, chitosan- tripolyphosphate nanoparticles were shown to be stable for a minimum of fifteen days in deionized water at 4°C. Conclusion:: The current study concludes the optimal conditions to formulate the chitosan nanoparticles with optimal physicochemical characteristics.

Chitosan Nanocarrier Entrapping Hydrophilic Drugs as Advanced Polymeric System for Dual Pharmaceutical and Cosmeceutical Application: A Comprehensive Analysis Using Box-Behnken Design

The objective of the present research is to propose chitosan as a nanocarrier for caffeine—a commonly used drug in combating cellulite. Being a hydrophilic drug, caffeine suffers from insufficient topical penetration upon application on the skin. Chitosan nanoparticles loaded with caffeine were prepared via the ionic gelation technique and optimized according to a Box–Behnken design. The effect of (A) chitosan concentration, (B) chitosan solution pH, and (C) chitosan to sodium tripolyphosphate mass ratio on (Y1) entrapment efficiency percent, (Y2) particle size, (Y3) polydispersity index, and (Y4) zeta potential were studied. Subsequently, the desired constraints on responses were applied, and validation of the optimization procedure was confirmed by the parameters exhibited by the optimal formulation. A caffeine entrapment efficiency percent of 17.25 ± 1.48%, a particle size of 173.03 ± 4.32 nm, a polydispersity index of 0.278 ± 0.01, and a surface charge of 41.7 ± 3.0 mV were attained. Microscopical evaluation using transmission electron microscope revealed a typical spherical nature of the nanoparticles arranged in a network with a further confirmation of the formation of particles in the nano range. The results proved the successful implementation of the Box–Behnken design for optimization of chitosan-based nanoparticles in the field of advanced polymeric systems for pharmaceutical and cosmeceutical applications.

Formulation, Optimization and Characterization of Chitosan Monodisperse Microparticles for Sustained Delivery of Hydrochlorothiazide HCl

Background: Hydrochlorothiazide HCl (HCTZ) is first line medication in the management of hypertension, however its poor solubility and GI irritation warrants long term application. The aim of present study was to prepare hydrochlorothiazide HCl (HCTZ) loaded monodisperse microparticles of chitosan (CS) for sustained delivery. Methods: In the present study chitosan microparticle were prepared using ionic gelation method. The effect of input parameters such as concentration of chitosan and pH of CS solution on the mean particle size (PS), zeta potential (ZP), polydispersity index (PDI) and in-vitro drug release were investigated. In-vitro drug release from the microparticles was studied using Franz diffusion cell. Structural formation and surface morphology was investigated using FTIR and SEM, respectively. Results: PS of CS microparticles ranges from 0.878±0.066 to 1.963±0.011 µm, ZP between 33.43±0.80 mV to 53.6±2.06 mV, PDI values from 0.271±0.063 to 0.842±0.073. The optimized CSMP- 3 (1.5% chitosan, pH 3) showed PS 1.672 ± 0.073 µm, ZP 53.6 ±2.06 mV, PdI 0.481±0.053, %EE 80.8±2.27% and HCTZ release of around 80% in 8 hours. FTIR reveals successful formation of crosslinked structure. SEM shows irregular surface owing preparation procedure. Drug kinetics modeled with Korsemeyer–Peppas equation revealed non-Fickian diffusion mechanism. Conclusion: Drug permeation study showed more than 70% of drug permeated through membrane. In conclusion, the CS microparticles can be used for the sustained delivery of HCTZ which would reduce the dosing frequency and improved patient compliance.

Effect of assembly pH and ionic strength of chitosan/casein multilayers on benzydamine hydrochloride release

Multilayer biopolyelectrolyte films are built from chitosan and casein by layer-by-layer deposition onto corona precharged poly(DL-lactic acid) substrate. Such structure allows optimization with respect to the morphology and ability of drug immobilization and release by changing the assembly conditions. Variation of chitosan and casein solutions ionic strength and chitosan solution pH at constant casein solution pH, effects significantly the polyelectrolyte multilayer structure and drug release. pH and ionic strength increase change the morphology from dense to loose, and the ionic strength increase let to screening effect and complexation of the drug, resulting in slow drug release.

Green synthesis, characterization and in vitro release of cinnamaldehyde/sodium alginate/chitosan nanoparticles

As a natural preservative, cinnamaldehyde (CA) has a bright application prospect. However, CA is sensitive to light and can be easily oxidized. What's more, its water solubility is poor. These properties greatly limit its application. In this study, CA/sodium alginate (SA)/chitosan (CS) nanoparticles (CA/SA/CS NPs) were prepared by using SA and CS as wall materials, and CA as core material. The single factor experiment showed that the optimal CA/SA/CS NPs can be obtained when the mass ratio of SA to CS was 5.5/1, SA to CaCl2 was 5/1, SA to CA was 1/2, and the pH of CS solution was 5.0. Under this condition, the average size of the prepared nanoparticles was 455.2 nm, polymer dispersity index (PDI) value was 0.189, zeta potential was −40.8 mV, and the encapsulation efficiency was 72.92%. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) images confirmed the formation of nanoparticles, which were spherical or ellipsoidal in shape. The fourier transform infrared spectroscopy (FTIR) and multifunctional polycrystalline X-ray diffraction (XRD) spectra indicated that CA was encapsulated in the nanoparticles. Furthermore, in vitro release experiments showed that CA/SA/CS NPs had the function of sustained release. In summary, SA/CS NPs can be used as a promising carrier for CA.

Influence of formulation parameters on encapsulation and release characteristics of curcumin loaded in chitosan-based drug delivery carriers

Drugs derived from plants with excellent chemotherapeutic effectiveness and relatively low toxicity may fail to scale through the phyto-drug discovery channel due to lack of appropriate drug delivery systems. These phytoceuticals need compatible carriers that will improve their stability, bioavailability and enhance their effectiveness. In this study, chitosan-based drug delivery carriers (DDCs) containing curcumin as phyto-drug model were prepared either via ionotropic gelation with tripolyphosphate or polyelectrolyte complexation with alginate. Influence of formulation parameters was evaluated using encapsulation and release characteristics as response indices. Crosslinking time, pH of chitosan solution and concentration of curcumin, alginate or tripolyphosphate significantly influenced the encapsulation efficiency, rate of curcumin release and mean release time (MRT) in simulated gastric fluid (SGF). Roughly spherical chitosan-based micro-beads with copious pores within the matrix and of improved encapsulation efficiency (82–93%) were prepared using optimized set of formulation parameters. Incorporation of alginate into the chitosan DDC reduced erosion of curcumin by 30% and extended MRT by 180 min in SGF without net delineating change in release profiles of curcumin in simulated physiological saline and intestinal fluids. Time-dependent in vitro study showed that radical scavenging activity ratio of curcumin was enhanced via encapsulation in chitosan-based DDCs.

Preparation, characterization and rheological behavior of chitosan nanocapsule emulsion encapsulated tuberose fragrance

Abstract In this paper, ionic gelation method was adopted to produce nanocapsules (CNs) encapsulated tuberose fragrance with chitosan (CS) and sodium tripolyphosphate (TPP) as wall materials. The effects of CS/TPP mass ratio, pH value of CS solution, molecular mass of CS and tuberose fragrance (TF) concentration on particle size and particle size distribution (PDI) of chitosan nanocapsules encapsulated tuberose fragrance (CNTs) were investigated systematically. CNTs were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analyzer (TGA) and differential scanning calorimetry (DSC). The results showed that CNTs were successfully prepared. The optimum preparation conditions were as follows: CS/TPP mass ratio 5:1, pH of CS solution 4.0, and molecular mass of CS 150 kda. CNTs emulsions were also systematically investigated by steady-state shear and oscillatory shear measurements respectively. The rheological behaviors of CNTs were obtained.

Optically Active Multilayer Films Based on Chitosan and an Azopolymer

The layer-by-layer technique has been widely adopted for the fabrication of nanostructures with tailored properties. In this work, photoactive multilayer films consisting of alternating layers of chitosan and an azopolymer were developed by this method. Taking into account that pH is the factor controlling the charge of weak polyelectrolytes, the influence of this parameter on the structure and properties of the multilayer films was evaluated. Thus, different films were prepared by varying pH conditions as well as bilayer number. The morphology and properties of the films were analyzed by diverse advanced techniques, such as ultraviolet-visible spectroscopy, X-ray diffraction, and atomic force microscopy equipped with PeakForce QNM (Quantitative Nanomechanical Property Mapping). It was found that the thickness, roughness and elastic modulus of the developed multilayer films increased with the decrease of the chitosan solution pH and the increase of the bilayer number. Furthermore, induced birefringence measurements revealed that a higher level of photo-orientation was attained with the decrease of pH and the increase of bilayer number.

Formulation and Evaluation of Betamethasone Sodium Phosphate Loaded Nanoparticles for Ophthalmic Delivery

Betamethasone sodium phosphate is a potent glucocorticoid with anti-inflammatory activity and can be used in treatment of macular edema. The aim of this work is to formulate and investigate mucoadhesive chitosan-sodium alginate nanoparticles as new vehicle for the prolonged topical ophthalmic delivery of betamethasone sodium phosphate. Ionotropic gelation method was used to produce betamethasone loaded chitosan alginate nanoreservoir system. The effect of changing different formulation parameters (pH of chitosan solution, sodium alginate concentration, calcium chloride concentration, chitosan concentration, drug concentration and the addition of tween 80) on the physicochemical properties and in vitro release of the drug loaded nanoparticles was studied. The mean particle size ranged from 16.8 to 692 nm and the zeta potential generally ranged from +18.49 to +29.83 mV depending on the formulation conditions. The highest encapsulating efficiency obtained was 64%. In vitro release studies showed an initial burst release of the drug followed by slow sustained release over 24, 48 or 72 hours depending on the formulation parameters. The in vivo studies carried out for two selected formulations showed the release of 84%, 59.5% of the drug over 12 hours for both F3C and F12 respectively. The results of physicochemical properties of F3C and F12 upon storage showed good stability at both 25°C and 40°C as the drug content was within the accepted range, the pH was (5–7) and the mean particle size for both formulations over the three months was still interesting for ophthalmic application. The results of this study suggest that chitosan alginate nanoparticles would be a promising system for the sustained release delivery of betamethasone sodium phosphate to the posterior segment of the eye.

Chitosan–lignosulfonates sono-chemically prepared nanoparticles: Characterisation and potential applications

Due to their recognised properties of biocompatibility, biodegradability and sustainability, chitosan nanocarriers have been successfully used as new delivery systems. In this work, nanoparticles combining chitosan and lignosulfonates were developed for the first time for cosmetic and biomedical applications. The ability of lignosulfonates to act as a counter polyion for stabilisation of chitosan particles, generated using high intensity ultrasound, was investigated. Several conditions for particles preparation were tested and optimised and the resulting nanoparticles were comprehensively characterised by measuring particle size, zeta potential and polydispersity index. The pH of chitosan solution, sonication time and the presence of an adequate surfactant, poloxamer 407, were determinant factors on the development of smaller particles with low polydispersity index (an average particle size of 230nm was obtained at pH 5 after 8min of sonication). The beneficial effects of lignosulfonates complex on chitosan nanoparticles were further characterised. Greater stability to lysozyme degradation, biocompatibility with human cells and antimicrobial activity was found upon lignosulfonates incorporation into chitosan nanoparticles. Furthermore, these particles were able to incorporate a hydrophilic model protein – RNase A. A burst release was observed when nanoparticles were loaded with low amount of protein while with high protein content, a sustained release was found, suggesting that the protein cargo maybe loaded both at the surface as in the bulk of the particle, depending on the concentration of drug incorporated.

Macroporous composite IPN hydrogels based on poly(acrylamide) and chitosan with tuned swelling and sorption of cationic dyes

The synthesis of macroporous ionic composite cryogels consisting of two independently cross-linked and oppositely charged networks is reported in the paper. Semi-interpenetrating network cryogels were prepared first by cross-linking polymerization of acrylamide (AAm) with N,N′-methylenebisacrylamide (BAAm) in the presence of chitosan (CS), under freezing conditions, the main parameters varied being cross-linker ratio (X), pH of the CS solution, and CS molar mass. The fraction of CS trapped in the semi-IPN cryogels increased with the increase of both X and pH of CS solution. The CS chains trapped in the semi-IPN cryogels have been cross-linked with epichlorohydrin under alkaline conditions, to generate the second network, when a partial hydrolysis of the amide groups in the PAAm matrix simultaneously occurred. Examination of scanning electron microscope images showed inter-connected macropores, in both semi-IPN and full-IPN cryogels. The generation of an anionic matrix during the formation of the second network led to a high sorption capacity of a model cationic dye, methylene blue (MB), by the full-IPN cryogel, around 750mg dye/g gel, at 25°C. The benefits of the full-IPN cryogels consist of their high reusability and in the high selectivity in separation of MB from the mixture with methyl orange.

Effect of the Chitosan on the Proliferation of the Microencapsulated Escherichia coli

Immobilization of microencapsulated cell is a kind of membrane technology. Therefore, the characteristics of membrane have a great impact on the growth of microorganisms. This study is designed to achieve the greatest growth rate of microencapsulated cell, Escherichia coli were immobilized in AC microcapsules made with different type of chitosan and then cultured in the Luria-Bertani medium. Effect of deacetylated degree (DD), molecular weight, membrane formation time and the pH of chitosan on the swelling ratio, cell release and proliferation were investigated at 2, 4, 6, 12, 24and 48h respectively. The results showed that the DD has no obviously influence on terminal biomass concentration, but the swelling ratio of membrane reached lowest when the DD was 90%. The biomass concentration increased with the rising of chitosan Mw and membrane formation time. Especially, the terminal biomass concentration near to 6.5×106·mL in the microcapsules made with 10KDa chitosan Mw ands 15min membrane formation time. Moreover, the swelling ratio closed to lowest point as the chitosan solution pH was 6.3.

SYNTHESIS AND CHARACTERIZATION OF CHITOSAN NANOPARTICLES WITH ENHANCED ANTIMICROBIAL ACTIVITY

The present paper demonstrates how the antimicrobial properties of chitosan can be enhanced by converting it into nanoparticles of desired size and surface charge using TPP (tripolyphosphate) initiated gelation process. It has been investigated and found that ionic gelation of cationic chitosan macromolecules offers a flexible and easily controllable process for systematically and predictably manipulating the particle size and surface charge of chitosan nano-particles which is an important property for antimicrobial effect. Variations in chitosan to TPP weight ratio, pH of chitosan solution and chitosan solution concentration during nanoparticle formation were examined systematically for their effects on nanoparticle size, intensity of surface charge, so as to enable faster synthesis of chitosan nanoparticles with desired properties to have optimum antimicrobial property. The data on particle size and zeta potential was obtained by dynamic light scattering (DLS) and electrophoretic mobility measurement of the chitosan nanoparticles respectively. UV-VIS absorption of bacterial suspension was measured at 610 nm to evaluate the bacterial reduction. Solution pH of chitosan was demonstrated to be the most critical factor in controlling particle size and surface charge. At very strong acidic condition of chitosan solution, cross-linking was less resulting in lower conversion of chitosan to chitosan nanoparticles which was reaffirmed by colloidal titration of the surface groups of the chitosan nanoparticles with negatively charged polyelectrolytes poly(vinyl sulfate kalium salt). It was found that variation in size and surface charge of chitosan nanoparticles could be achieved by changing all the above mentioned process parameters and resulted in significant variation in their antimicrobial activity.