Effects of a nanoemulsion with Copaifera officinalis oleoresin against monogenean parasites of Colossoma macropomum: A Neotropical Serrasalmidae.

Monogeneans are ectoparasites that may cause losses in production and productivity in the aquaculture of Colossoma macropomum. Chemotherapeutics used in aquaculture usually have major adverse effects on fish; hence, the use of essential oils has been considered advantageous, but these are not soluble in water. Thus, the use of nanostructures to enhance water solubility of compounds and improve bioactivity may be very promising. This study investigated the antiparasitic activity of nanoemulsion prepared with Copaifera officinalis oleoresin (50, 100, 150, 200 and 300 mg/L), against monogenean parasites from the gills of C. macropomum. The particle size distribution and zeta potential suggested that a potentially kinetic stable system was generated. The nanoemulsion from C. officinalis oleoresin achieved high efficacy (100%) at low concentrations (200 and 300 mg/L) after 15 min of exposure. This was the first time that a nanoemulsion was generated from C. officinalis oleoresin using a solvent-free, non-heating and low-energy method. Moreover, this was the first time that an antiparasitic against monogeneans on fish gills, based on nanoemulsion of C. officinalis oleoresin, was tested.

Surface functionalization of macroporous polymeric materials by treatment with air low temperature plasma.

Polystyrene/divinylbenzene (PS-DVB) macroporous monoliths obtained using highly concentrated emulsions as templates show a superhydrophobic behaviour, restricting their potential technological applications, especially those related to adhesion and wetting. Air plasma treatments were carried out in order to modulate wetting properties, modifying the surface chemical composition of macroporous polystyrene/divinylbenzene materials. The superhydrophobic behaviour was rapidly suppressed by air plasma treatment, greatly reducing the water contact angle, from approximately 150 degrees to approximately 90 degrees, in only 10 seconds of treatment. The new surface chemical groups, promoted by plasma active species, were characterized by surface analysis techniques with different depth penetration specificity (contact angle, XPS, FTIR and SEM). Results demonstrated that very short treatment times produced different chemical functionalities, mainly C-O, C=O, O-C=O and C-N, which provide the materials with predominantly acidic surface properties. However, plasma active species did not penetrate deeply through the interconnected pores of the material. FTIR analysis evidenced that the new hydrophilic surface groups promoted by plasma active species are in a negligibly concentration compared to bulk chemical groups, and are located in a very thin surface region on the PS-DVB monolith surface (significantly below 2 microm). XPS analysis of treated monoliths revealed a progressive increase of oxygen and nitrogen content as a function of plasma treatment time. However, oxidation of the PS-DVB monoliths surface prevails over the incorporation of nitrogen atoms. Finally, SEM studies indicated that the morphology of the plasma treated PS-DVB does not significantly change even for the longest air plasma treatment time studied (120 s).

Use of hydrophobically modified inulin for the preparation of polymethyl methacrylate/polybutyl acrylate latex particles using a semicontinuous reactor.

The seeded semicontinuous emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BuA) stabilized with a graft polymeric surfactant based on inulin, INUTEC SP1, as well as its mixture with sodium lauryl sulfate (SLS) is described. The mixture of SLS and Brij58 (alcohol ethoxylated) and the mixture of SLS and Pluronic P85 (block copolymer PEO-PPO-PEO) are also used as surfactant systems. The addition of methacrylic acid (MAA) or acrylic acid (AA) as comonomers is also studied. Previous results proved this inulin-derivative surfactant, INUTEC SP1, to be very effective on synthesizing latexes using a very low surfactant concentration. The kinetic features of the emulsion polymerization (instantaneous conversion and total conversion) were gravimetrically determined along the reactions. Latex dispersions were characterized by photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) to obtain the average particle size, the particle size distributions (PSDs) as well as the polydispersity index (PdI). The stability was determined by turbidimetry measurements and expressed in terms of critical coagulation concentration. The results showed that the use of the graft polymeric surfactant allowed obtaining highly stable nanoparticles, at low surfactant concentrations and high solid contents (up to 37 wt %). This is an improvement with respect to previous works, in which a mixture of the graft polymeric surfactant with another surfactant was required to obtain stable nanoparticles with low polydispersity, at high solid content. In the present work, low polydispersity was achieved using INUTEC as the only emulsifier, which was related to the absence of secondary nucleations. When a mixture of INUTEC SP1 and SLS is used, a wider PSD is obtained due to secondary nucleations. Replacing INUTEC SP1 by other nonionic surfactants such as Brij58 or Pluronic P85 leads to an increase of average particle size and wider PSD.

Ethylcellulose nanoparticles as a new "in vitro" transfection tool for antisense oligonucleotide delivery.

Oil-in-water nano-emulsions have been obtained in the HEPES 20 mM buffer solution / [Alkylamidoammonium:Kolliphor EL = 1:1] / [6 wt% ethylcellulose in ethyl acetate] system over a wide oil-to-surfactant range and above 35 wt% aqueous component at 25 °C. The nano-emulsion with an oil-to-surfactant ratio of 70/30 and 95 wt% aqueous component was used for nanoparticles preparation. These nanoparticles (mean diameter around 90 nm and zeta potential of +22 mV) were non-toxic to HeLa cells up to a concentration of 3 mM of cationic species. Successful complexation with an antisense phosphorothioate oligonucleotide targeting Renilla luciferase mRNA was achieved at cationic/anionic charge ratios above 16, as confirmed by zeta potential measurements and an electrophoretic mobility shift assay, provided that no Fetal Bovine Serum is present in the cell culture medium. Importantly, Renilla luciferase gene inhibition shows an optimum efficiency (40%) for the cationic/anionic ratio 28, which makes these complexes promising for "in vitro" cell transfection.

Modulating size and surface charge of ethylcellulose nanoparticles through the use of cationic nano-emulsion templates.

Ethylcellulose nano-emulsions have been obtained by the low-energy phase inversion composition method in the Water / [Alkylamidoammonium: Cremophor WO7] / [6% ethylcellulose in ethyl acetate] system at 25 °C. It is shown that nano-emlulsions' composition variables (oil-to-surfactant ratio, cationic: nonionic surfactant ratio and polymer and water content) produce changes in their droplet diameter, surface charge and colloidal stability following defined trends. Nano-emulsions with good stability, droplet diameters between about 120 and 200 nm and surface charge from about 10 to 50 mV have been obtained. Nano-emulsions are further used as templates for nanoparticle dispersions preparation, which show sizes and surface charges typically smaller and similar respectively to their nano-emulsion templates. Cationic: nonionic surfactant ratio has the highest influence on both, size and surface charge, followed by oil-to-surfactant ratio and water content. Interestingly, the positive charge of the nanoparticles can be depleted under diluting conditions in a time-dependent manner.

Low-energy nano-emulsification approach as a simple strategy to prepare positively charged ethylcellulose nanoparticles.

Positively charged ethylcelulose nanoparticles have been obtained from alkylamidoammonium/Span 80 based nano-emulsion templates. Oil-in-water polymeric nano-emulsions form in a broad range of oil-to-surfactant ratios and water contents above 75 wt% by a low-energy method at 25 °C. Nano-emulsions with a water content of 90 wt% showed droplet sizes typically below 300 nm and high positive zeta potential values (∼55 mV). If oleylamine is added to the system, smaller droplet sizes and higher zeta potential values (∼66 mV) are obtained, but the stability of the nano-emulsions decreases. Although these nano-emulsions are destabilized by creaming, the period of stability is large enough to allow nanoparticle preparation by solvent evaporation. Polymeric nanoparticles obtained show a globular core-shell-like morphology, with mean diameters of around 250 nm. The surface charge of the nanoparticles is similar to that of the nano-emulsion template and remains positive after 24 h dialysis, suggesting slow desorption kinetics of the alkylamidoammonium from the nanoparticle surface. These results indicate that the proposed nano-emulsion approach is a good strategy for the preparation of positively charged nanoparticles from nonionic ethylcellulose polymers.

Hyaluronan based materials with catanionic sugar-derived surfactants as drug delivery systems.

In the present work novel drug delivery systems consisting in highly porous Hyaluronan foams for the administration of a non-steroidal anti-inflammatory drug (NSAID), ketoprofen, have been obtained. A sugar-derived surfactant associated with ketoprofen was prepared and incorporated into the porous hyaluronan materials. The association between a lactose derived surfactant, Lhyd12, and ketoprofen was obtained by acid-base reaction and its physicochemical properties were studied. Tensiometric and dynamic light scattering (DLS) determinations showed the formation of catanionic surfactant aggregates, Lhyd12/ketoprofen, in aqueous solution. Furthermore, the catanionic surfactants allowed greater solubilisation of ketoprofen. Hyaluronan porous materials were developed using butanediol diglycidyl ether as crosslinking agent. The profile release of Lhyd12/ketoprofen from hyaluronan based materials shows differences as a function of the aggregation state of catanionic surfactant.

Phase and rheological behavior of the polymerizable surfactant CTAVB and water.

The phase and rheological behaviors of the polymerizable surfactant, cetyltrimethylammonium benzoate (CTAVB), and water as a function of surfactant concentration and temperature are investigated here. The critical micelle concentration (cmc) and the (cmc(2)), as well as the Krafft temperature (T(K)), are reported. A large highly viscous micellar solution region and hexagonal- and lamellar-phase regions were identified. The micellar solutions exhibit shear thickening in the dilute regime, below the overlapping or entanglement concentration. At higher concentrations, wormlike micelles form and the solutions show strong viscoelasticity and Maxwell behavior in the linear regime and shear banding flow in the nonlinear regime. The linear viscoelastic regime is analyzed with the Granek-Cates model, showing that the relaxation is controlled by the kinetics of reformation and scission of the micelles. The steady and unsteady responses in the nonlinear regime are compared with the predictions of the Bautista-Manero-Puig (BMP) model. Model predictions follow the experimental data closely.

Design of parenteral MNP-loaded PLGA nanoparticles by a low-energy emulsification approach as theragnostic platforms for intravenous or intratumoral administration.

Encapsulation of magnetic nanoparticles (MNP) into PLGA nanoparticles has been achieved by nano-emulsion templating using for the first time both, a low-energy emulsification method as well as biocompatible components accepted for pharmaceuticals intended for human use. The incorporation of MNP by nano-emulsion templating method proposed in this work has been investigated in two different systems applying mild process conditions and is shown to be simple and versatile, providing stable MNP-loaded PLGA nanoparticles with tunable size and MNP concentration. MNP-loaded PLGA nanoparticles showed sizes below 200nm by DLS and 50nm by TEM, and mean MNP loading per PLGA nanoparticle of 1 to 4, depending on the nanoparticle dispersion composition. Physical-chemical features suggest that the MNP-loaded PLGA nanoparticles obtained are good candidates for intravenous or intratumoral administration.

Self-Assembly and Formation of Chromonic Liquid Crystals from the Dyes Quinaldine Red Acetate and Pyronin Y.

The aqueous self-assembly behavior of the dyes Quinaldine red acetate and Pyronin Y in a wide range of concentrations is reported here for the first time. (1)H NMR spectroscopy, polarized-light optical microscopy, and small and wide X-ray scattering were used to get insight into molecular interactions, phase boundaries and aggregate structure. Quinaldine red acetate and Pyronin Y self-organize into unimolecular stacks driven by attractive aromatic interactions. At high concentrations, spatial correlation among the molecular stacks gives rise to nematic liquid crystals in both systems. Quinaldine red acetate additionally produces a rare chromonic O phase built of columnar aggregates with anisotropic cross-section ordered in a rectangular lattice. The O phase changes into a columnar lamellar structure as a result of a temperature-induced phase transition. Results open the possibility of finding chromonic liquid crystals in other commercially available dyes with a similar molecular structure. This would eventually expand the availability of these unique soft materials and thus introduce new applications for marketed dyes.

Studies on the formation of polymeric nano-emulsions obtained via low-energy emulsification and their use as templates for drug delivery nanoparticle dispersions.

Ethylcellulose nanoparticles have been obtained from O/W nano-emulsions of the water/polyoxyethylene 10 oleyl ether/[ethyl acetate+4wt% ethylcellulose] system by low energy-energy emulsification at 25°C. Nano-emulsions with droplet sizes below 200nm and high kinetic stability were chosen for solubilising dexamethasone (DXM). Phase behaviour, conductivity and optical analysis studies of the system have evidenced for the first time that both, the polymer and the drug play a role on the structure of the aggregates formed along the emulsification path. Nano-emulsion formation may take place by both, phase inversion and self-emulsification. Spherical polymeric nanoparticles containing surfactant, showing sizes below 160nm have been obtained from the nano-emulsions by organic solvent evaporation. DXM loading in the nanoparticles was high (>90%). The release kinetics of nanoparticle dispersions with similar particle size and encapsulated DXM but different polymer to surfactant ratio were studied and compared to an aqueous DXM solution. Drug release from the nanoparticle dispersions was slower than from the aqueous solution. While the DXM solution showed a Fickian release pattern, the release behaviour from the nanoparticle dispersions was faster than that expected from a pure Fickian release. A coupled diffusion/relaxation model fitted the results very well, suggesting that polymer chains undergo conformational changes enhancing drug release. The contribution of diffusion and relaxation to drug transport in the nanoparticle dispersions depended on their composition and release time. Surfactant micelles present in the nanoparticle dispersion may exert a mild reservoir effect. The small particle size and the prolonged DXM release provided by the ethylcellulose nanoparticle dispersions make them suitable vehicles for controlled drug delivery applications.

PLGA nanoparticles from nano-emulsion templating as imaging agents: Versatile technology to obtain nanoparticles loaded with fluorescent dyes.

The interest in polymeric nanoparticles as imaging systems for biomedical applications has increased notably in the last decades. In this work, PLGA nanoparticles, prepared from nano-emulsion templating, have been used to prepare novel fluorescent imaging agents. Two model fluorescent dyes were chosen and dissolved in the oil phase of the nano-emulsions together with PLGA. Nano-emulsions were prepared by the phase inversion composition (PIC) low-energy method. Fluorescent dye-loaded nanoparticles were obtained by solvent evaporation of nano-emulsion templates. PLGA nanoparticles loaded with the fluorescent dyes showed hydrodynamic radii lower than 40nm; markedly lower than those reported in previous studies. The small nanoparticle size was attributed to the nano-emulsification strategy used. PLGA nanoparticles showed negative surface charge and enough stability to be used for biomedical imaging purposes. Encapsulation efficiencies were higher than 99%, which was also attributed to the nano-emulsification approach as well as to the low solubility of the dyes in the aqueous component. Release kinetics of both fluorescent dyes from the nanoparticle dispersions was pH-independent and sustained. These results indicate that the dyes could remain encapsulated enough time to reach any organ and that the decrease of the pH produced during cell internalization by the endocytic route would not affect their release. Therefore, it can be assumed that these nanoparticles are appropriate as systemic imaging agents. In addition, in vitro toxicity tests showed that nanoparticles are non-cytotoxic. Consequently, it can be concluded that the preparation of PLGA nanoparticles from nano-emulsion templating represents a very versatile technology that enables obtaining biocompatible, biodegradable and safe imaging agents suitable for biomedical purposes.

PLGA nanoparticles prepared by nano-emulsion templating using low-energy methods as efficient nanocarriers for drug delivery across the blood-brain barrier.

Neurodegenerative diseases have an increased prevalence and incidence nowadays, mainly due to aging of the population. In addition, current treatments lack efficacy, mostly due to the presence of the blood-brain barrier (BBB) that limits the penetration of the drugs to the central nervous system. Therefore, novel drug delivery systems are required. Polymeric nanoparticles have been reported to be appropriate for this purpose. Specifically, the use of poly-(lactic-co-glycolic acid) (PLGA) seems to be advantageous due to its biocompatibility and biodegradability that ensure safe therapies. In this work, a novel approximation to develop loperamide-loaded nanoparticles is presented: their preparation by nano-emulsion templating using a low-energy method (the phase inversion composition, PIC, method). This nano-emulsification approach is a simple and very versatile technology, which allows a precise size control and it can be performed at mild process conditions. Drug-loaded PLGA nanoparticles were obtained using safe components by solvent evaporation of template nano-emulsions. Characterization of PLGA nanoparticles was performed, together with the study of the BBB crossing. The in vivo results of measuring the analgesic effect using the hot-plate test evidenced that the designed PLGA loperamide-loaded nanoparticles are able to efficiently cross the BBB, with high crossing efficiencies when their surface is functionalized with an active targeting moiety (a monoclonal antibody against the transferrin receptor). These results, together with the nanoparticle characterization performed here are expected to provide sufficient evidences to end up to clinical trials in the near future.

Galantamine-loaded PLGA nanoparticles, from nano-emulsion templating, as novel advanced drug delivery systems to treat neurodegenerative diseases.

Polymeric nanoparticles could be promising drug delivery systems to treat neurodegenerative diseases. Among the various methods of nanoparticle preparation, nano-emulsion templating was used in the present study to prepare galantamine-loaded nano-emulsions by a low-energy emulsification method followed by solvent evaporation to obtain galantamine-loaded polymeric nanoparticles. This approach was found to be suitable because biocompatible, biodegradable and safe nanoparticles with appropriate features (hydrodynamic radii around 20 nm, negative surface charge and stability higher than 3 months) for their intravenous administration were obtained. Encapsulation efficiencies higher than 90 wt% were obtained with a sustained drug release profile as compared to that from aqueous and micellar solutions. The enzymatic activity of the drug was maintained at 80% after its encapsulation into nanoparticles that were non-cytotoxic at the required therapeutic concentration. Therefore, novel galantamine-loaded polymeric nanoparticles have been designed for the first time using the nano-emulsification approach and showed the appropriate features to become advanced drug delivery systems to treat neurodegenerative diseases.

Body composition and spontaneous growth hormone secretion in normal short stature children.

This study was designed to compare the relationship of measured and estimated indices of adiposity with the spontaneous GH secretion (SGHS) in 37 normal short stature children. Fifteen of the 37 patients (10 males and 5 females) were pubertal, and 22 (17 males and 5 females) were prepubertal. All patients underwent a review of their medical history, a physical exam, laboratory tests, and a nutritional assessment that included anthropometry and evaluation of body composition by bioelectric impedance. The percentage of body fat and body fat mass index were used as measured indices of adiposity. The weight for height ratio, body mass index, and body mass index z-scores were calculated and used as estimated indices of adiposity. Our results showed that SGHS is greatly influenced by variations in adiposity in normal short stature children, and measured indices of adiposity demonstrated the strongest negative correlation with SGHS. Gender differences were apparent in the degree of adiposity that modified SGHS, and it appears that adiposity altered the amplitude of GH pulses in pubertal patients and the number of pulses in prepubertal children. These results suggest that interpretation of SGHS must take into account body composition and gender in addition to pubertal status.

Formation and stability of nano-emulsions.

This review describes the principles of formation and stability of nano-emulsions. It starts with an introduction highlighting the main advantages of nano-emulsions over macroemulsions for personal care and cosmetic formulations. It also describes the main problems with lack of progress on nano-emulsions. The second section deals with the mechanism of emulsification and the dynamic light scattering technique for measurement of the droplet size of nano-emulsions. This is followed by a section on methods of emulsification and the role of surfactants. Three methods are described for nano-emulsion preparation, namely high energy emulsification (using homogenisers), low energy emulsification whereby water is added to an oil solution of the surfactant and the principle of the phase inversion temperature (PIT). A section is devoted to steric stabilisation and the role of the adsorbed layer thickness. The problem of Ostwald ripening (which is the main instability process of nano-emulsions) is described in some detail. The methods that can be applied to reduce Ostwald ripening are briefly described. This involves the addition of a second less soluble oil phase such as squalene and/or addition of a strongly adsorbed and water insoluble polymeric surfactant. The last part of the review gives some examples of nano-emulsions that are prepared by the PIT method as well as using high pressure homogeniser. A comparison of the two methods is given and the rate of Ostwald ripening is measured in both cases. The effect of changing the alkyl chain length and branching of the oil was investigated using decane, dodecane, tertadecane, hexadecane and isohexadecane. The branched oil isohexadcecane showed higher Ostwald ripening rate when compared with a linear chain oil with the same carbon number.

A common method for the determination of several calcium channel blockers using an HPLC system with ultraviolet detection.

We report a common HPLC method for the single or simultaneous determination of four calcium channel blockers (CCB), namely diltiazem (DTZ), verapamil (VER), nifedipine (NIF) and nitrendipine (NIT) and their active metabolites demetildiltiazem and deacetildiltiazem (MA and M1), norverapamil (NOR), and dehydronifedipine (DHN). DHN was first synthesised in our laboratory and different pH values of the mobil phase were subsequently prepared and tested for chromatographic separation. The detection system and the environmental light conditions were optimised. The best separations of all analytes were obtained using a C(18) column and a mobile phase of methanol, 0.04 M ammonium acetate, acetonitrile and triethylamine (2:2:1:0.04 v/v). Quantitation was performed using imipramine (IMI) as the internal standard. For DTZ and its metabolites (M1 and MA), the wavelength chosen was 237 nm; for VER and its metabolite NOR, it was 210 nm; and, finally for NIF and its metabolite DHN and NIT it was 216 nm. When a simultaneous analysis was carried out the wavelength was of 230 nm. The optimum pH were 7.90 and 7.10 when the separation of NIT and DTZ or VER and NIF were carried out, respectively, and 7.90 when a simultaneous separation was carried out. The detection limit of the assay was less than 8 ng ml(-1) for all compounds, with coefficients of variation less than 7% (for inter- and intra-day) over the concentration range of 1-1000 ng ml(-1). The retention times were less than 11 min. When NIF or NIT were studied, it was necessary to use a sodium vapour lamp in order to avoid the photodegradation which takes place under daylight conditions.

Comparative pharmacokinetics of enrofloxacin in mice, rats, rabbits, sheep, and cows.

OBJECTIVE: To compare pharmacokinetic variables of enrofloxacin (ENR) after IV administration in mice, rats, rabbits, sheep, and cows and to perform allometric analysis of ENR. ANIMALS: 47 mice, 5 rats, 5 rabbits, 5 sheep, and 5 cows. PROCEDURE: Serially obtained plasma samples were assayed for ENR concentration, using high-performance liquid chromatography. In vitro plasma protein binding was determined by ultrafiltration. Plasma ENR concentration versus time curves were fitted by use of nonlinear least-squared regression analysis. Pharmacokinetic variables were correlated further with body weight. RESULTS: In all species studied, the best fit was obtained for a two-compartment open model; ENR half-life ranged from 89 minutes in mice to 169 minutes in cows. Volume of distribution was large in all species studied, with values ranging from 10.5 L/kg in mice to 1.5 L/kg in sheep. Body clearance ranged from 68.1 ml/min/kg for mice to 4.6 ml/min/kg for sheep. Unbound ENR was found to be (mean +/- SD) 58+/-2, 50+/-6, 50+/-2, 31+/-2, and 40+/-3% in plasma of mice, rats, rabbits, sheep, and cows, respectively. The only pharmacokinetic variables that could be correlated with body weight were elimination half-life, clearance, and volume of distribution. Allometric exponents denoting proportionality of half-life, body clearance, and volume of distribution with body weight were 0.06, 0.82, and 0.90, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: An allometric approach could provide a suitable method for determining a scale for ENR pharmacokinetics among various mammalian species. This would faciliatate the administration of appropriate doses of ENR to all animals.

Determination of orbifloxacin in rabbit plasma by high-performance liquid chromatography with fluorescence detection.

A simple and sensitive high-performance liquid chromatography method is developed for the determination of orbifloxacin (ORB) in rabbit plasma. Sample preparations are carried out by adding phosphate buffer (pH 7.4, 0.1 M) and extracting with trichloromethane. ORB and the internal standard, norfloxacin (NOR), are separated on a reversed-phase column using an aqueous phosphate buffer-acetonitrile (80:20, v/v) mobile phase. The concentrations of ORB and NOR eluting from the column with retention times of 2.16 and 3.09 min, respectively, are monitored by fluorescence detection at 338 (excitation) and 425 nm (emission). The method is shown to be linear from 4 to 1500 ng/mL (regression coefficient r2 = 0.999). The quantitation and detection limits are 4 and 9 ng/mL, respectively. Mean recovery is determined as 92% by the analysis of plasma standards containing 150, 750, and 1500 ng/mL. Inter- and intra-assay precisions were 4 and 3%, respectively.

In situ chitosan gelation initiated by atmospheric plasma treatment.

This work reports on the feasibility of atmospheric dielectric barrier discharge (DBD) plasma as a novel synthetic pathway for the liquid phase gelation of chitosan. The DBD plasma chitosan gelation process did not significantly alter the chemical structure of the biopolymer as confirmed by FTIR study. However, the oxidation processes and local heating effect associated with the solvent evaporation during the plasma treatment could provoke both reaction of chitosan degradation and the cleavage of ß-1-4-glycosidic linkages with the concomitant generation of aldehyde groups able to crosslink via Schiff-base with amino groups from other chitosan molecules. Shear viscosity measurements suggested the formation of chitosan fragments of lower molecular weight after the plasma treatment of 1% (w/v) chitosan and fragments of higher molecular weight after the plasma treatment of 2% (w/v) chitosan. The crosslinking density of hydrogels generated during the in situ DBD plasma chitosan gelation process increased as a function of the treatment time and concentration of chitosan. As of consequence of the increase of the cross-linking density, the equilibrium swelling ratio and water content decreased significantly.