Cationic Biopolymer Research Articles

Modification of interfacial characteristics of monodisperse droplets produced using membrane emulsification by surfactant displacement and/or polyelectrolyte electrostatic deposition

This study examined the possibility of modifying the interfacial characteristics of uniformly sized droplets produced by premix membrane emulsification using surfactant-displacement and/or electrostatic deposition methods. The non-ionic surfactant Tween 20 is particularly effective at producing uniformly sized lipid droplets by premix membrane emulsification, but the droplets produced have a low net charge. The interfacial characteristics of emulsion droplets initially coated by Tween 20 could be made either negative or positive (without altering droplet size) by adding controlled amounts of either anionic emulsifiers (SDS) or cationic emulsifiers (DTAB or β-lactoglobulin) to the continuous phase after homogenisation. In addition, cationic emulsion droplets could be prepared by depositing a cationic biopolymer (chitosan) onto the surfaces of anionic droplets (SDS/Tween coated). These results have important consequences for the design, fabrication and utilisation of uniformly sized lipid droplets with controlled interfacial characteristics.

Preparation and characterization of chitosan nanocomposites with vermiculite of different modification

In this study, the biopolymer chitosan/vermiculite (VMT) nanocomposites were prepared by the solution mixing process of the cationic biopolymer chitosan with three different modified VMT (HVMT, NVMT, and OVMT), which was treated by hydrochloride, sodium, and cetyl trimethyl ammonium bromide (CTAB), respectively. Wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) have been employed in the characterization of chitosan/HVMT, chitosan/NVMT, and chitosan/OVMT nanocomposites. Both WAXD data and TEM images of chitosan nanocomposites indicated that the silicate layers were disorderedly dispersed into the chitosan matrix in nano scale. The thermal stability of chitosan/HVMT nanocomposites have the greatest improvements compared to that of neat chitosan, chitosan/NVMT and chitosan/OVMT nanocomposites. It provides a potential approach to prepare high performance and low-cost chitosan nanocomposite.

Determination of molar mass and solution properties of cationic hydroxyethyl cellulose derivatives by multi‐angle laser light scattering with simultaneous refractive index detection

AbstractBACKGROUND: A complete understanding of the molar mass and solution properties of raw materials in bio/pharmaceutical products under bio‐application and natural conditions ensures process control, product performance and quality. Biopolymers including polymeric cationic hydroxyethyl cellulose derivatives (e.g. Polyquaterium‐10 or Polymer JR) have long been used in health care formulations including shampoos, lotions, eye drops and contact lens multi‐purpose solutions. Previously reported molar masses and conformation of Polymer JR were based on size exclusion chromatography‐related techniques, which required highly concentrated buffered salt solutions and organic solvent modifiers to prevent undesirable interactions, and did not represent the isotonic conditions in products and applications.RESULTS: This paper describes the characterization of Polymer JR in saline using a new approach that combines micro‐batch mode multi‐angle laser light scattering with simultaneous refractive index measurements (MB‐MALLS‐RI). Mass‐average molar mass, z‐average radius of gyration and second virial coefficient values in phosphate buffer saline (PBS) were obtained and are discussed in detail.CONCLUSION: The molar mass and solution properties of Polymer JR in PBS, with the same pH and ionic strength as most health care solution products, can be characterized using the MB‐MALLS‐RI technique. The approach is practical and can be widely used for the analysis of other cationic biopolymers. Copyright © 2009 Society of Chemical Industry

285. Development of a Novel Cationic Biopolymer for Targeted Cancer Gene Therapy

285. Development of a Novel Cationic Biopolymer for Targeted Cancer Gene Therapy

Adsorption of Cr(VI) and As(V) on Chitosan-Montmorillonite: Selectivity and pH Dependence

AbstractMontmorillonite modified with the cationic biopolymer, chitosan, has, in weak acidic solutions, protonated amine groups which act as anion-adsorption sites. Due to the specific surroundings of the adsorption sites and diffusion paths in the interlayer of chitosan-montmorillonite, preferential adsorption of certain anions is likely. In the present study, the adsorption properties for the inorganic anions Cr(VI) and As(V) were determined, taking into account solution pH and competitive adsorption in the presence of Cl− and SO42−${\rm{SO}}_4^{2 - }$. Chitosan-montmorillonite was prepared by adding an amount of chitosan equivalent to 500% of the cation exchange capacity (CEC) at pH 5 and 75°C. The resulting anion exchange capacity was ∼0.34 molc/kg. The adsorption properties for As(V) and Cr(VI) were determined with the batch technique at pH 3 to 9. Adsorption isotherms were fitted to the Langmuir and Dubinin-Radushkevich equations and judged quantitatively by the correlation coefficient. To describe the competitive adsorption, the selectivity (S) was determined by the ratio of amounts of anions A and B adsorbed (qA/qB) in a binary system. The ionic species adsorbed, i.e. either Cr(VI) or As(V), depended on the pH, as did the degree of protonation of the amine groups, and this played a decisive role in the amount of anions adsorbed. The maximum amount of Cr(VI) adsorbed was 180 mmol/kg at pH 3.5, whereas for As(V) it was 120 mmol/kg at pH 4.0 to 5.0. The adsorption process of Cr(VI) and As(V) fit well to the Langmuir isotherm. By increasing the concentration of the competitive anion, Cl−, in solution, the amount of Cr(VI) and As(V) adsorbed remained almostconstant, whereas SO42−${\rm{SO}}_4^{2 - }$ had a more pronounced competitive effect. At concentration ratios of 0.5 and 1 for SO42−${\rm{SO}}_4^{2 - }$ to Cr(VI) and As(V), respectively, the sorption capacity decreased by 10 and 25%, respectively. The sequence of the selectivity was: Cr(VI)>SO42−>As(V)>Cl−${\rm{Cr}}\left( {{\rm{VI}}} \right) > {\rm{SO}}_4^{2 - } > {\rm{As}}\left( {\rm{V}} \right) > {\rm{C}}{{\rm{l}}^ - }$. Chitosan-montmorillonite showed a high selectivity for Cr(VI), which adsorbed chemically. Despite the lower affinity for As(V) and physical adsorption, the adsorption capacity was relatively high.

Spinning Carbon Nanotube-Gel Fibers Using Polyelectrolyte Complexation

Biopolymer-single walled carbon nanotube (SWNT)-biopolymer fibers were prepared using a continuous flow spinning approach. Polyelectrolyte complexation was facilitated by injecting a SWNT-biopolymer dispersion into a coagulation bath containing a biopolymer of opposite charge. We showed that the ability to spin fibers and their properties depend on processing conditions such as polyelectrolyte pH, sonolysis regime (conditions employed to disperse SWNT) and the order of adding the anionic and cationic biopolymer solutions. Maximizing the ionic nature through changes in the pH increased spin-ability, while combining a sonicated dispersion with an as-prepared (non-sonicated) polyelectrolyte solution allowed us to optimize sonolysis conditions while retaining spin-ability of fibers with smooth surface morphology. Addition of the cationic biopolymer-SWNT dispersion to the anionic biopolymer solution resulted in mechanical reinforcement with the increase in SWNT loading fraction. All fibers decreased their electrical resistance upon exposure to water vapor.

Studies of the association of chitosan and alkylated chitosan with oppositely charged sodium dodecyl sulfate

Cationic biopolymer chitosan has many applications in food, cosmetic and pharmaceutical industries. Grafting alkylated chains on its backbone can hydrophobically modify this water-soluble polymer. This paper concerns unmodified chitosan, alkylated chitosan and their interactions with a model anionic surfactant, sodium dodecyl sulfate (SDS). The solvent is pH 4 acetic acid solution. The purpose of this study is to highlight the hydrophobicity brought by the alkylated chains by comparing surface tension measurements and rheological properties of hydrophobically modified polymer (HMP) and chitosan solutions at 25 °C. Interactions of chitosan and HMP with surfactant have also been investigated giving information about surface activity and electrical conductivity of such systems. It results that alkylated chitosan/SDS system is more surface active than chitosan/SDS and it offers new potential applications in pharmaceutical and cosmetic fields because of the formation of amphiphilic complexes.

Mono- N-carboxymethyl chitosan (MCC) and N-trimethyl chitosan (TMC) nanoparticles for non-invasive vaccine delivery

Mucosal application of a vaccine can effectively induce both systemic and mucosal immune responses. In general, mucosal applications of antigens result in poor immune responses. Therefore, adjuvant/delivery systems are required to enhance the immune response. Chitosan is a cationic biopolymer which exerts advantages as a vaccine carrier due to its immune stimulating activity and bioadhesive properties that enhance cellular uptake and permeation as well as antigen protection. Similar effects are also shown by chitosan derivatives. In this study, the nanoparticulate systems were prepared by using differently charged chitosan derivatives, N-trimethyl chitosan (TMC, polycationic), and mono- N-carboxymethyl chitosan (MCC, polyampholytic) for mucosal immunisation. The derivatives were synthesised and characterised in-house. The aqueous dispersions of the derivatives were also prepared for comparison. The cytotoxicity studies (MTT assay) on Chinese hamster ovary (CHO-K1) cell lines showed that cell viability was in the order of MCC, chitosan and TMC. Nanoparticles were prepared using ionic gelation method and loaded with tetanus toxoid (TT). Nanoparticles with high loading efficacy (>90% m/m), particle size within the range of 40–400 nm, with a negative surface charge for MCC and positive surface charge for TMC and chitosan were obtained. The structural integrity of the TT in the formulations was confirmed by SDS-PAGE electrophoresis analysis. The effective uptake of the FITC-BSA loaded nanoparticles into the cells was demonstrated by cellular uptake studies using J774A.1 cells. Immune responses induced by the formulations loaded with tetanus toxoid were studied in vivo in Balb/c mice. Enhanced immune responses were obtained with intranasal (i.n.) application of nanoparticle formulations. Chitosan and TMC nanoparticles which have positively charged surfaces induced higher serum IgG titres when compared to those prepared with MCC which are negatively charged and smaller in size. Nanoparticle formulations developed in this study can be used as promising adjuvant/delivery systems for mucosal immunisation.

Study of the complex formation between sodium dodecyl sulfate and hydrophobically modified chitosan

The cationic biopolymer chitosan has many applications in the food, cosmetic and pharmaceutical industries. In this paper, grafted alkylated side chains on the chitosan backbone hydrophobically modify this water-soluble polymer. In this study, cationic HMP is characterized (acetylation degree and substitution degree) and polymer–surfactant complexes formed with anionic surfactant Sodium Dodecyl Sulfate (SDS) are investigated. Solvent is a pH 4 acetic acid solution T = 25 °C. Binding isotherms and surface tension measurements have been made. The structure of the complexes in the bulk phase has been studied by turbidity and zeta potential measurements. Isothermal titration calorimetry (ITC) allowed some conclusions to be drawn concerning the extent of the hydrophobic interactions. It is concluded from the determination of optimal ionic ratio shows that the alkylated chitosan/SDS system could be used as wall material for capsules using the coacervation process.

Examination of the Interaction of Chitosan and Oil-in-Water Emulsions Under Conditions Simulating the Digestive System Using Confocal Microscopy

ABSTRACT Chitosan is a cationic biopolymer that has been used extensively in dietary supplements to reduce fat absorption in the fight against obesity. The mechanism of fat binding of chitosan is still not fully understood and has been the subject of controversy. This study was designed to improve the understanding of the underlying mechanism by investigating the interaction of chitosan with oil-in-water emulsion droplets. Our results indicated that (0.1% w/w) chitosan adsorbed to a 20% w/w phosphatidylcholine-stabilized anionic primary emulsion to form a secondary cationic emulsion by electrostatic attraction forces under conditions resembling the stomach (pH 2). Bile salts (6 mM) were added to simulate secretion in the small intestine and pH increase. Bile salts adsorbed to the chitosan secondary emulsion, which resulted in aggregation of oil droplets followed by coalescence due to close packing of droplets. Increased viscosity (267–2531 cp) and increased degree of deacetylation (40–92% DDA) of chitosan enhanced emulsion breakdown. Increasing the pH to 7.5 without addition of bile salts yielded little aggregation. Pronounced aggregation is thought to decrease the accessibility of lipase to the oil resulting in lower bioavailability and reduced caloric intake. Understanding how chitosan interacts with oil droplets in the digestive tract is vital to developing a comprehensive model of the influence of chitosan on the bioavailability of dietary lipids. The information gained in this study may be useful for the interpretation and experimental design of animal and human feeding studies and for the rational design of chitosan-based functional foods for fat reduction.

Ionization and Solubility of Chitosan Solutions Related to Thermosensitive Chitosan/Glycerol-Phosphate Systems

Chitosan is a linear cationic biopolymer composed of glucosamine and N-acetyl-glucosamine that is only soluble in acidic aqueous solutions and precipitates when neutralized. However, it was recently discovered that chitosan dissolved in solutions containing glycerol phosphate was soluble at near neutral pH and produced a sol-gel transition when heated. Understanding this unique thermogelling system requires improved characterization of the ionization and solubility behaviors of chitosan, in particular dependencies on temperature, salt, chitosan concentration, and fD, where fD is the fraction of glucosamine monomers (deacetylated monomers) in chitosan. In the current study we performed temperature-controlled titration and dilution experiments on chitosan solutions with fD of 0.72, 0.85, and 0.98 at concentrations ranging from 1.875 to 30 mM of its glucosamine monomer and with 0 to 150 mM added salt. Light transmittance measurements were performed during titration to indicate precipitation. We found the apparent proton dissociation constant of chitosan, pKap, to (1) decrease strongly with increased temperature, (2) increase strongly with increased salt, (3) increase strongly with increased chitosan concentration in low-salt conditions, and (4) decrease weakly with increasing fD. All of the above influences on chitosan pKap were accurately predicted using a mean-field Poisson-Boltzmann (PB) cylindrical cell model where the only adjustable parameter was the temperature-dependent chitosan intrinsic monomeric dissociation constant pK0(T). The resulting chitosan pK0 values at 25 degrees C were in the range from 6.63 to 6.78 for all chitosans and salt contents tested. The temperature dependence of chitosan ionization was found to strongly reduce pK0(T) by 0.023 units per degrees C, for example, resulting in a reduction of chitosan pK0(T) from 7.1 at 5 degrees C to 6.35 at 37 degrees C for fD of 0.72 in 150 mM salt. A similar temperature-dependent reduction of the pKa of the glucosamine monomer was found (-0.027 units per degrees C) while the pKa of glycerol phosphate did not change significantly with temperature. The latter result suggested that chitosan solutions heated in the presence of glycerol phosphate will become partly neutralized by transferring protons to glycerol phosphate and thereby allow attractive interchain forces to form a physically cross-linked gel under the appropriate conditions. Additionally, the degree of ionization of chitosan when it precipitates upon addition of a strong base was measured to be in the range from 0.25 to 0.55 and was found to (1) be insensitive to temperature, (2) increase strongly with increased salt, and (3) increase strongly with fD. The salt effect was accounted for by the PB model, while the influence of fD appeared to be due to acetyl groups impeding attractive chain-to-chain association to increase solubility and require reduced ionization levels to precipitate.

Chitosan as a Lipid Binder: A Langmuir Monolayer Study of Chitosan−Lipid Interactions

Owing to its distinct chemico-biological properties, chitosan, a cationic biopolymer, offers a great potential in multifarious bioapplications. One such application is as a dietary antilipidemic supplement to be used to reduce obesity/overweight and to lower cholesterol. The lipid-binding efficiency of chitosan, however, remains debatable. Accordingly, in this study we investigated the interactions of chitosan with selected lipids, cholesterol and fatty acids, the latter including saturated (stearic acid) and unsaturated (oleic, linoleic, alpha-linolenic) acids. The experiments were performed with the Langmuir monolayer technique, in which surface pressure-area isotherms were recorded for the lipid monolayers spread on the acetate buffer pH 4.0 subphase in the absence and presence of chitosan. We found that the presence of chitosan in the subphase strongly influenced the shape and location of the isotherms, proving that there existed attractions between chitosan and lipid molecules. The attractions were revealed by changes of the molecular organization of the monolayers. The common feature of these changes was that all the monolayers studied underwent expansion, in each case reaching saturation with increasing chitosan concentration. In agreement with the lipid molecular structures, the highest expansions were observed for the most unsaturated fatty acids, linoleic and alpha-linolenic, the lowest for stearic acid, with oleic acid and cholesterol being the intermediate cases. By contrast, the main distinguishing feature of these changes was that, although none of the monolayers studied changed its state when completely saturated with chitosan, compared to the parent ones the compactness of the monolayers was modified. The solid monolayers of stearic acid and cholesterol were loosened, whereas those of all the unsaturated acids, liquid in nature, were tightened. On the basis of these results we tentatively propose a mechanism of the chitosan action that includes both electrostatic and hydrophobic lipid-chitosan interactions as well as hydrogen bonding between them.

ITO electrode modified with chitosan nanofibers loading polyoxometalate by one step self-assembly method and its electrocatalysis

Chitosan is a cationic biopolymer that has many electrochemical applications because of its ability to interact with anionic surface-active molecules. In present experiment, chitosan nanofibers were successfully deposited on indium tin oxide (ITO) substrates by electrospinning chitosan solution. After neutralization with saturated Na 2CO 3 aqueous solution to maintain its fibrous structure, α-[P 2W 18O 62] 6− (abbr. P 2W 18) was immobilized on the chitosan nanofibers by one step self-assembly technique. The scanning electron microscope (SEM) images showed that P 2W 18 was mainly deposited on chitosan nanofibers. The cyclic voltammetric responses showed three well redox couples of P 2W 18. Electrochemical behavior of the electrode prepared under different condition of pH value was investigated. In addition, the modified electrode exhibited high electrocatalytic activity for reduction of NO 2 - .

Preparation of Properties of Biodegradable Membranes Using Natural Polymer/Clay Nanocomposite for the Application of Dehumidification

Biodegradable chitosan/clay nanocomposite membranes were prepared by solution casting method for the application of dehumidification. The cationic biopolymer, chitosan was intercalated into clay through cationic exchange and hydrogen bonding process. Diluted acetic acid was used as a solvent for dissolving and dispersing chitosan into clays. Chitosan was successfully intercalated into clay and it was confirmed by X-ray diffraction method. Thermal stability and the mechanical properties of the nanocomposites are characterized by TGA and Universal Testing Machine. Thermal stability and mechanical properties were enhanced by increasing clay contents in chitosan/clay nanocomposites. Gas permeation and water vapor permeation properties of the nanocomposites were measured by time-lag methods. Permeability of N2 gas and water vapor through chitosan/clay nanocomposite membranes decreased when the content of clay in the nanocomposite increased.

Characterization of chitosan nanofiber fabric by electrospray deposition: Electrokinetic and adsorption behavior

Cationic biopolymer nanofiber fabrics were prepared from a chitosan/poly(ethylene oxide) blend solution by electrospray deposition. Their electrokinetic properties and DNA adsorption behavior were analyzed as a function of pH. The zeta potential was determined from streaming potential/streaming current measurements. The adsorption of DNA onto the fabrics was investigated by spectrophotoscopy. The adsorption behavior of DNA correlated well with the electrokinetic properties of the fabrics. This revealed that the electrokinetic approach was a useful option for characterization of novel nanofiber assemblies made by the electrostatic spray process. In addition, these results provided fundamental information about chitosan nanofiber fabrics for both biomedical and analytical applications.

Self-Assembly and Physicochemical and Rheological Properties of a Polysaccharide−Surfactant System Formed from the Cationic Biopolymer Chitosan and Nonionic Sorbitan Esters

Self-Assembly and Physicochemical and Rheological Properties of a Polysaccharide−Surfactant System Formed from the Cationic Biopolymer Chitosan and Nonionic Sorbitan Esters

Evaluation of Cationic Biopolymers for the Design of Silica-coated Alginate Capsules

ABSTRACTLysozyme and chitosan were evaluated as cationic polymers for the design of silica-coated alginate capsules. No direct relationship was found between the strength of the bio-organic poly-electrolyte membrane and the stability of capsules after the silica coating, which depends mainly on the nature of poly-cation/silicate interactions.

Self-Assembly and Physicochemical and Rheological Properties of a Polysaccharide−Surfactant System Formed from the Cationic Biopolymer Chitosan and Nonionic Sorbitan Esters

The natural cationic polysaccharide chitosan was mixed with the nonionic surfactants sorbitan monolaurate, sorbitan monooleate, or sorbitan triooleate to produce a biopolymer-surfactant system with unique properties. The mixtures of chitosan and surfactant formed emulsion-like solutions and/or creams. The known properties of the components were considered (i.e., hydrophile-lipophile balance, molecular weight, structure, and density), and various physicochemical and rheological properties of the mixtures were measured. Specifically, the critical micelle concentration of the sorbitan esters in a chitosan solution was measured using both surface tension and fluorescence-based methods. The concentration-dependent morphologies of the aggregates within the chitosan-surfactant solutions were evaluated by optical microscopy and dynamic light scattering. A schematic depicting the possible molecular arrangement of chitosan and surfactant within the various formulations was produced from consideration of the experimental findings. The degree of interaction between chitosan and the individual surfactants was assessed by FTIR analysis. The rheological properties of the chitosan-surfactant emulsions were also investigated and found to be related to the observed morphologies. Overall, clear composition-property relationships were established for these chitosan-surfactant systems which have potential applications in the food and pharmaceutical industries.

Pulmonary inflammation caused by chitosan microparticles

Chitosan is a cationic biopolymer derived from chitin with potential therapeutic applications such as controlled drug delivery to mucosal-epithelial surfaces in the body. Inhaled chitosan microparticles (CM), for example, are of potential interest in pulmonary pharmacotherapy. In this context, we examine some basic reactions of lung tissue to CM. Inhaled CM (2-10 mg/kg of particles) induce dose-dependent proinflammatory effects in rat lungs; these effects are documented in increases in bronchoalveolar lavage fluid protein (BALF-P) and lactate dehydrogenase activity (BALF-LDH) and increases in lung tissue myeloperoxidase (MPO) activity and leukocyte migration. Overall, the biochemical parameters (i.e., average of BALF-P, BALF-DH, and MPO) indicate that the inflammation response is 1.8-fold greater than controls without CM; the same inflammation parameters, however, are 1.9-fold lower with CM compared with the proinflammatory effects of lipopolysaccharide (LPS). Cytological examination of BALF shows a large infiltration of polymorphonuclear neutrophils to lung tissue: more than a sixfold increase in this population of inflammatory cells, after inhalation of CM relative to air inhalation controls. Thus, the results indicate that inhaled CM can have significant proinflammatory effects on lung tissues; these effects are mild relative to LPS but need to be considered in the context of therapeutic applications via pulmonary delivery if such concentrations of CM are used.

Isothermal titration calorimetry study of the interactions between chitosan and a bile salt (sodium taurocholate)

The binding of bile acids to dietary fibers in the small intestine has been proposed as a mechanism for the reduction of blood cholesterol levels. In this study, isothermal titration calorimetry (ITC) was used to characterize the binding of sodium taurocholate (NaTC) to a cationic biopolymer (chitosan). The influence of ionic strength (0–150 mM NaCl) and temperature (10–40 °C) on the binding interactions was examined (pH 3, acetate buffer). At 30 °C, NaTC bound strongly to chitosan to form an insoluble complex that contained about 4×10 −3 mol of NaTC per 1 g of chitosan at saturation. The presence of salt (0–150 mM NaCl, pH 3) decreased the critical micelle concentration (CMC) of NaTC (in both the absence and presence of chitosan), increased the minimum NaTC concentration required for binding to be observed, but had little influence on the amount of NaTC bound to chitosan at saturation. The enthalpy changes associated with micelle dissociation went from exothermic at low-holding temperatures (10 °C) to endothermic at higher holding temperatures (40 °C). Conversely, the enthalpy changes associated with NaTC–chitosan binding went from endothermic at low-holding temperatures (10 °C) to exothermic at higher holding temperatures (40 °C). The temperature dependence of these processes indicated the importance of changes in hydrophobic interactions within the systems. This study provides information that may lead to the rational design of chitosan-based ingredients or products with improved cholesterol lowering ability.