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This study describes the comparison between the interaction of a series of peptide-functionalized chitosan-based nanocapsules and liposomes with two cell lines, i.e., mouse macrophages RAW 264.7 and human endothelial cells EA.hy926. Both types of nanocarriers are loaded with magnetic nanoparticles and designed for anti-inflammatory therapy. The choice of these magnetic nanostructures is argued based on their advantages in terms of size, morphology, chemical composition, and the multiple possibilities of modifying their surface. Moreover, active targeting might be ensured by using an external magnetic field. To explore the impact of chitosan-based nanocapsules and liposomes on cell cytophysiology, the cell viability, using the MTT assay, and cell morphology were investigated. The results revealed low to moderate cytotoxicity of free nanocapsules and significant cytotoxicity induced by chitosan-coated liposomes loaded with dexamethasone, confirming its release from the delivery system. Thus, after 48 h of treatment with nanocapsules, the viability of RAW 264.7 cells varied between 88.18% (OCNPM-1I, 3.125 µg/mL) and 76.37% (OCNPM-1, 25 µg/mL). In the same conditions, EA.hy926 cell viability was between 99.91% (OCNPM-3, 3.125 µg/mL) and 75.15% (OCNPM-3, 25 µg/mL) at the highest dose (25 µg/mL), the values being comparable for both cell lines. Referring to the cell reactivity after dexamethasone-loaded liposome application, the lowest viability of RAW 264.7 cells was 41.25% (CLDM5CP-1, 25 µg/mL) and 58.20% (CLDMM2CP-1 1.25 µg/mL) in the endothelial cell line, proving a selective character of action of nanocarriers. The cell morphology test, performed to support and confirm the results obtained by the MTT test, revealed a differentiated response for the two types of nano-carriers. As expected, an intense cytotoxic effect in the case of dexamethasone-loaded liposomes and a lack of cytotoxicity for drug-free nanocapsules were noticed. Therefore, our study demonstrated the biocompatible feature of the studied nanocarriers, which highlights them for future research as potential drug delivery systems for pharmacological applications, including anti-inflammatory therapy.

Lung infections, such as: pneumonia, chronic obstructive cystic fibrosis, tuberculosis are generally caused by viruses, bacteria and fungi. As these infections are very difficult to treat, new therapeutic approaches are investigated in order to maximize the efficiency of the treatment and to reduce the major complications that can occur. The main objective of this study was focused on the preparation of drug-loaded peptides-functionalized microcapsules, obtained by a double emulsion, based on carboxylated chitosan (CMCS), poly(vinyl alcohol) (PVA) and an activator [4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride] (DMT-MM), for the dual active targeting and treatment of pulmonary infections. The microcapsules were functionalized on the surface with both CGSPGWVRC and indolicidin (IN) peptides, as effective ligands for the active targeting of both alveolar capillary endothelial cells and bacterial cells. FTIR spectroscopy confirmed the formation of ester and amide bonds into the structure of prepared microcapsules. Microcapsules diameter varied between 893 and 965 nm. The swelling degree in PBS, at pH 7.4, ranged between 1760 %- 2100 %. All the analyzed samples showed hemolysis degrees lower than 2 %, which demonstrated their non-hemolytic character. Evaluation of the impact of microcapsules on WI-38 normal human lung cells and RAW 264.7 mouse macrophages revealed a non-toxic or slightly cytotoxic effect. Internalization assay proved that microcapsules were localized at intracellular level., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Polymeric microcapsules are extensively investigated as drug delivery systems for a broad range of applications. In the present study, Dexamethasone-loaded carboxylated chitosan (CCS)/poly (vinyl alcohol) (PVA)-based microcapsules were prepared in view of their potential administration by inhalation for the treatment of lung diseases. The crosslinking between PVA and CCS was activated by [4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride] (DMT-MM) and the FTIR results proved the formation of ester bonds between the two polymers. The sizes of the obtained microcapsules are influenced by the ratio between the polymers but also by the concentration of the DMT-MM activator. Moreover, the amount of PVA in the system has an important influence on swelling degree, encapsulation efficiency, drug release degree, biodegradation and protein adsorption. The sample with the highest amount of PVA has the highest crosslinking density and thus the lowest swelling degree and encapsulation efficiency. However, an encapsulation degree of 61.3% was obtained for the sample MCP-6 with the lowest PVA content. The same sample showed the lowest BSA adsorption. A controlled and sustained Dexamethasone release of around 90% was observed in PBS at pH 7.4 and 37 °C during 24 h. All the obtained samples were hemocompatibles and thus can be used as efficient drug delivery systems., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Popa Marcel reports financial support was provided by CNCS - UEFISCDI., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Cross-linked chitosan (CS) films with aldehyde groups obtained by oxidation of carboxymethyl cellulose (CMC) with NaIO 4 were prepared using different molar ratios between the CHO groups from oxidized carboxymethyl cellulose (CMCOx) and NH 2 groups from CS (from 0.25:1 to 2:1). Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy demonstrated the aldehyde groups' presence in the CMCOx. The maximum oxidation degree was 22.9%. In the hydrogel, the amino groups' conversion index value increased when the -CHO/-NH 2 molar ratio, cross-linking temperature, and time increased, while the swelling degree values decreased. The hydrogel films were characterized by scanning electron microscopy (SEM) and FTIR analysis. The curcumin encapsulation efficiency decreases from 56.74% to 16.88% when the cross-linking degree increases. The immobilized curcumin release efficiency (R Ef %) and skin membrane permeability were evaluated in vitro in two different pH solutions using a Franz diffusion cell, and it was found to decrease when the molar ratio -CH=O/NH 2 increases. The curcumin R Ef % in the receptor compartment was higher at pH = 7.4 (18%- for the sample with a molar ratio of 0.25:1) than at pH = 5.5 (16.5%). The curcumin absorption in the skin membrane at pH = 5.5 (47%) was more intense than at pH = 7.4 (8.6%). The curcumin-loaded films' antioxidant activity was improved due to the CS presence.

The aim of the study was to create a mathematical model useful for monitoring the release of bioactive aldehydes covalently bonded to the chitosan by reversible imine linkage, considered as a polymer-drug system. For this purpose, two hydrogels were prepared by the acid condensation reaction of chitosan with the antifungal 2-formyl-phenyl-boronic acid and their particularities; influencing the release of the antifungal aldehyde by shifting the imination equilibrium to the reagents was considered, i.e., the supramolecular nature of the hydrogels was highlighted by polarized light microscopy, while scanning electron microscopy showed their microporous morphology. Furthermore, the in vitro fungicidal activity was investigated on two fungal strains and the in vitro release curves of the antifungal aldehyde triggered by the pH stimulus were drawn. The theoretical model was developed starting from the hypothesis that the imine-chitosan system, both structurally and functionally, can be assimilated, from a mathematical point of view, with a multifractal object, and its dynamics were analyzed in the framework of the Scale Relativity Theory. Thus, through Riccati-type gauges, two synchronous dynamics, one in the scale space, associated with the fungicidal activity, and the other in the usual space, associated with the antifungal aldehyde release, become operational. Their synchronicity, reducible to the isomorphism of two SL(2R)-type groups, implies, by means of its joint invariant functions, bioactive aldehyde compound release dynamics in the form of "kink-antikink pairs" dynamics of a multifractal type. Finally, the theoretical model was validated through the experimental data.

Cancer remains one of the world's most devastating diseases and is responsible for more than 20% of all deaths. It is defined as uncontrolled proliferation of cells and spreads rapidly to healthy tissue. Controlled drug delivery systems offers great opportunities for the development of new non-invasive strategies for the treatment of cancers. The main advantage of these systems is their capacity to accumulate in tumors via enhanced permeability and retention effects. In the present study, an innovative hybrid drug delivery system based on nanocapsules obtained from the interfacial condensation between chitosan and poly(N-vinyl pyrrolidone- alt -itaconic anhydride) and containing both magnetic nanoparticles and an antitumoral drug was developed in order to improve the efficiency of the antitumoral treatment. Using dynamic light scattering, it was observed that the mean diameter of these hybrid nanocapsules was in the range of 43 to 142 nm. SEM confirmed their nanometric size and their well-defined spherical shape. These nanocapsules allowed the encapsulation of an increased amount of 5-fluorouracil and provided controlled drug release. In vitro studies have revealed that these drug-loaded hybrid nanocapsules were able to induce a cytostatic effect on breast carcinoma MCF-7 cell lines (Human Caucasian breast adenocarcinoma - HTB-22) comparable to that of the free drug.

The aim of the present study is to obtain, for the first time, polymeric nanocarriers based on the chitosan grafted-poly(ethylene glycol) methacrylate derivative. The strategy involves the use of chitosan grafted-poly(ethylene glycol) methacrylate with high solubility in water, obtained via Michael addition, in order to prepare potentially non-toxic micro/nanoparticles (MNPs). By modifying chitosan, its solubility in aqueous media was improved. Micro/nanoparticles-based chitosan grafted-poly(ethylene glycol) methacrylate were obtained under mild condition, with good and controlled swelling properties in acetate buffer solution (ABS) and phosphate buffer solution (PBS). The technique selected for the preparation of the MNPs was a double crosslinking (ionic and covalent) process in reverse emulsion which provide the mechanical stability of the polymeric nanocarrier. The chitosan derivative and MNPs were thoroughly characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM). The Scanning Electron Microscopy photographs revealed that prepared MNPs have different diameters depending on the used stirring rate and polymer concentration. Nanoparticles potential as drug delivery system was analyzed by loading bevacizumab (BEV) a full-length monoclonal antibody. Also, the prepared particles were found suitable from the cytotoxicity and hemocompatibility point of view enabling their potential use as delivery system for the treatment of posterior segment of the eye conditions., (Copyright © 2019. Published by Elsevier B.V.)

The aim of the present study is to obtain, for the first time, polymer magnetic nanoparticles based on the chitosan-maltose derivative and magnetite. By chemically modifying the chitosan, its solubility in aqueous media was improved, which in turn facilitates the nanoparticles' preparation. Resulting polymers exhibit enhanced hydrophilia, which is an important factor in increasing the retention time of nanoparticles in the blood flow. The preparation of nanoparticles relied on the double crosslinking technique (ionic and covalent) in reverse emulsion which ensures the mechanical stability of the polymer carrier. The characterization of both the chitosan derivative and nanoparticles was accomplished by Fourier Transform Infrared Spectroscopy, Nuclear Magnetic Resonance Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, Atomic Force Microscopy, Vibrating Sample Magnetometry, and Thermogravimetric Analysis. The evaluation of morphological, dimensional, structural, and magnetical properties, as well as thermal stability and swelling behavior of nanoparticles was made from the point of view of the polymer/magnetite ratio. The study of 5-Fluorouracil loading and release kinetics as well as evaluating the cytotoxicity and hemocompatibility of nanoparticles justify their adequate behavior in their potential use as devices for targeted transport of antitumor drugs., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Chitosan gelatin particles could be the ideal candidate for intraocular drug delivery due to their desirable properties. Double crosslinking in double emulsion has been used as an original and reliable method for particles preparation and their morphology has been optimized considering the main synthesis parameters such as polymers ratio, crosslinker amount, stirring speed, tensioactive amount and ionic crosslinking time, respectively. The particles have been analyzed for their physical-chemical properties (swelling degree, drug loading and release capacity, surface characteristics, etc.), the enzymatic degradation properties along with in vivo ocular investigations (ocular biodistribution, in vivo drug release). In the present study cefuroxim was used as a model drug, which is generally used in the prophylaxis of postoperative endophthalmitis following cataract surgery after intraocular administration. The present study proved that the dimensions and the physical-chemical properties of the particles can be modulated (by varying the preparation parameters) to facilitate the administration, the biodistribution and the drug release in the specific segment of the eye. This experimental study demonstrated also the ability of fluorescent nanoparticles to penetrate ocular tissues close to the administration site (intravitreal injection) and especially their tendency to migrate deep in the retina at time intervals of 72 h., (Copyright © 2015. Published by Elsevier B.V.)

Aim: To evaluate intraocular biodistribution of fluorescent nanoparticles composed of dexamethasone bound to chitosan after intravitreal administration in rabbit eyes., Material and Methods: The chitosan and gelatin based nanoparticles were synthetized using a reverse emulsion-double crosslinking technique (ionic and covalent) and then dexamethasone was bound. Two units of 1% suspension of these nanoparticles in saline solution were injected intravitreally into rabbit eyes. The histologic sections obtained at 72 hours were analyzed by confocal microscopy., Results: The chitosan-fluorescein conjugate bound to dexamethasone was present in all ocular tissues at 72 hours. The nanoparticles were present in the retina and lens in a larger amount than in the other ocular tissues., Conclusions: The reverse emulsion-double crosslinking technique was efficient in synthesizing a biocompatible polymeric nanosystem. The in vivo study of intraocular biodistribution of fluorescein-marked nanoparticles capable of binding dexamethasone revealed their affinity for the retina and lens after intravitreal administration.

Spherical microparticles for encapsulation of drugs for the treatment of diseases, with a diameter ranging between 2 and 4 µm, were obtained by double crosslinking (ionic and covalent) of chitosan and poly(vinyl alcohol) blend in a water-in-oil emulsion. Microparticles characterisation was carried out in terms of structural, morphological and swelling properties in aqueous media. The presence of chitosan in particles composition confers them a pH-sensitive character. Toxicity and hemocompatibility tests prove the biocompatible character of microparticles. The pilocarpine loading capacity is high as well as the release efficiency which increases up to 72 and 82% after 6 h. The obtained results recommend the microparticles as sustained release drug carriers for the treatment of eye diseases.

The study proposes modeling calcein release kinetics (considered as a hydrophilic drug model) from an interpenetrating network matrix of hydrogels, based on the combination of two polymers, of which chitosan is the most commonly used polymer. The release process is analyzed for different increasing time intervals, based on the evolution of the release kinetics. For each time interval, a dominant release mechanism was identified and quantitative analyses were performed, to probe the existence of four distinct stages during its evolution with each stage governed by a different kinetics model. An interesting and original aspect, which is analyzed through a novel approach, is that of drug release at longer time scales, which is often overlooked. It revealed that the system behaves as a complex one and its evolution can be described through a nonlinear theoretical model, which offers us new insights into its order-disorder evolution.

The paper describes the preparation of chitosan/gelatin hydrogels, obtained by double crosslinking with glutaraldehyde and sodium sulphate/sodium tripolyphosphate that may be used as matrices for the inclusion of drug loaded liposomes composed of phosphatidylcholine. The main objective was to create a protective layer to stabilize the liposomal surface and to prolong/control the release of drugs from such systems. Therefore, complex systems capable of prolonged drug release and controlled release kinetics were obtained. Samples consisting of different chitosan/gelatin ratios and type/amount of ionic crosslinker have been prepared and characterized. The present study shows that calcein (used as a model hydrophilic drug) release from polymeric hydrogels has been retarded from several days to weeks after calcein inclusion in small unilamellar vesicles (SUVs) and multilamellar vesicles (MLVs) entrapped subsequently in hydrogels with variable composition. The calcein release kinetics of complex systems were compared to simple systems (control hydrogels) and important changes were observed thus proving that the mechanism of the process increases in complexity. Also, it is demonstrated that liposomes' stability can be greatly improved by inclusion in polymeric matrices. Multilamellar liposomes showed a better release behaviour, which indicates that these calcein loaded vesicles remained intact to some extent after release from the matrix, due to their improved stability provided by the multiple layers. When small unilamellar liposomes were tested, calcein have been released from hydrogels predominantly in a free form (due to their unilamellarity related instability even inside the hydrogel) but in a sustained and controllable manner. The main applications of the systems obtained are in the area of drug release for tissue engineering/tissue repair (topical administration of drugs for wound therapy - burns, for example). Hydrogels capable of delivering drugs over prolonged periods of time represent a step forward in wound management and many diseases that request long term and sustained delivery of drugs. These hydrogels could be used as tissue replacement or injectable depot systems in many high risk diseases including cancer., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The aim of this study was to evaluate intraocular biodistribution of a fluorescent polymeric nanosystem composed of chitosan and gelatin after intravitreal administration in rat eyes. The nanoparticles based on chitosan and gelatin were synthesized using a reverse emulsion-double cross-linking technique (ionic and covalent) and their structural characteristics are presented. Two units of 1% suspension of fluorescein-labeled nanoparticles in saline solution were injected intravitreal in rat eyes. The histological cross-sections obtained at 24 and 72 hours were analyzed by confocal microscopy and compared to a similar number of control cross-sections. The scanning electron microscopy of the nanoparticles obtained by double cross-linking in reverse emulsion technique revealed spherical, smooth, highly porous particles with no tendency to form aggregates. The chitosan-fluorescein conjugate was present in all the ocular tissues both at 24 and at 72 hours. The nanoparticles were present in the retina in a larger quantity and persisted longer than in the other ocular tissues. They were mainly fixed paravascular. The double cross-linking in reverse emulsion technique was efficient in synthesizing a biocompatible polymeric nanosystem. The in vivo study of intraocular biodistribution of fluorescein-labeled nanoparticles revealed their affinity for the retina after intravitreal administration.

This work reports on the physicochemical properties and in vitro cytotoxicity assessment of chitosan-calcium phosphate (Cs-CP) scaffolds for bone tissue engineering, which were synthesized by a novel biomimetic co-precipitation method. X-ray diffraction (XRD) along with scanning electron microscopy (SEM) analysis confirmed the porous morphology of the scaffolds and the amorphous nature of the inorganic phase with different crystallite sizes and the formation of various forms of calcium phosphate. Compressive mechanical testing revealed that the Young's modulus of the biomaterials is in the range of human trabecular bone. In vitro tests were performed on the biomaterials for up to 14 days to study the behavior of the osteoblast-like human cell line (MG63), primary human osteoblasts (HOS) and human dermal microvascular endothelial cells (HDMEC). The cytotoxicity was evaluated by the MTS assay for cell metabolism and the detection of membrane integrity (lactate dehydrogenase-LDH release). An expression of the vascular endothelial growth factor (VEGF) in the cell supernatants was quantified by ELISA. Cell viability gave values close to untreated controls for MG63 and HOS, while in the case of HDMEC the viability after 2 weeks in the cell culture was between 80-90%. The cytotoxicity induced by the Cs-CP scaffolds on MG63, HOS and HDMEC in vitro was evaluated by the amount of LDH released, which is a sensitive and accurate marker for cellular toxicity. The increased levels of VEGF obtained in the osteoblast culture highlights its important role in the regulation of vascularization and bone remodeling. The biological responses of the Cs-CP scaffolds demonstrate a similar proliferation and differentiation characteristics of the cells comparable to the controls. These results reveal that biomimetic Cs-CP composite scaffolds are promising biomaterials for bone tissue engineering; their in vivo response remains to be tested.

The development of polymer nanosystems able to target and control/sustain the drug delivery is still considered an important desideratum in pharmaceutical research. The present study reports the preparation of nanoparticles based on chitosan and gelatin, using a reverse emulsion-double crosslinking (ionic followed by covalent one) technique. The nanoparticles structural and morphological characteristics (diameter and size distribution), their swelling capacity in aqueous media of different pH (4 and 7.4) and their ability to include and release poorly water-soluble drugs were seen to be influenced by the composition of the polymer mixture and by the surfactants concentration. Also, nanoparticles biodistribution after intraperitoneal or intravenous administration was evaluated by polymer marking with fluorescein. Particles ability to penetrate different organs (liver, heart, lungs, and less brain, gums, testicles) was increased when injected intravenously., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The first goal of this work was to develop a method for obtaining interpenetrating gelatin (G)-chitosan (CS) networks prepared by double cross-linking (covalent followed by ionic) that exhibit hydrogel character. The second goal was to modulate their properties as a function of the preparation parameters by using neural network models. This study was therefore carried out by experiment and simulation. The covalent cross-linking resulted from the reaction between the carbonyl groups of glutaraldehyde with amino groups belonging to both polymers; the ionic cross-linking is based on the interaction between tripolyphosphate anions and protonated amine groups (ammonium ions) of the polymers. The total cross-linking density (indirectly assessed by estimating the water swelling capacity) and the ability to include hydrosoluble bioactive principles are influenced by the following process parameters: the CS/G ratio, the amount of ionic cross-linker, and the ionic cross-linking time. The prepared hydrogels were characterized with respect to their structural, morphological, and some physical properties. The hydrogels ability to load high amounts of water-soluble drugs indicates their potential use as carriers for biologically active principles in the human body. A neural network methodology was applied to model the swelling degree and caffeine loading/release capacity depending on reaction conditions; in addition, applying this method, the optimal preparation conditions have been determined, targeting pre-established values for swelling degree or maximum caffeine value. The accuracy of the results obtained through this technique proves that the neural networks are suitable tools for modeling cross-linking processes taking place complex nonlinear polymers., (Copyright © 2011 Wiley Periodicals, Inc.)

Nowadays the management of ocular diseases is limited by the inability for controlled drug delivery. In the present study micro and nanoparticles based on Chitosan labeled with fluorescein, prepared by double crosslinking method in water/oil emulsion, were investigated as a new vehicle for intraocular drug delivery. The main objective was to study the biodistribution of the prepared particles after beind administered into the anterior chamber of pig eyes. Nanoparticles were characterized by Scanning Electron Microscopy Laser Difractometry and analysis was performed by Confocal Laser Microscopy. The designed micro and nanoparticles have average size from 500 nm to 2 microm and present round shape, smooth surface, relative high dimensional poly-dispersity and relative high porosity. The particles also present good biodistribution at corneal, scleral, retinal and optic nerve level after being administered. After this eliminary phase we intend to use Chitosan based nanoparticles as a controlled drug delivery system for therapies concerning endophthalmitis, age related macular degeneration etc.

Nanostructured membranes and films of cationic surfactant-chitosan with tannic acid as polyphenol model were obtained by phase inversion method. The membranes were investigated by Attenuated Total Reflectance Fourier Transform InfraRred, X-Ray Diffraction, Scanning Electron Microscopy and Thermogravimetry, and the films topography was analysed by Atomic Force Microscopy. The analysis reveals that the interactions at the molecular level between cationic CTAB surfactant and cationic chitosan polymer strive to weaken membrane stability, whereas, the tannic acid is favoured to cluster with CTAB and diminish the membrane thermodynamic instability. The nanocapsules formed, with dimensions in the range of 16.35-27.68 nm, are congregating in clusters having dimensions in the domain of 50-300 nm. The layers resulted from these nanostructures arrangement constitute a surfactant-chitosan matrix with tannic acid suitable for drug controlled release with zero order kinetics.

The formation of double cross-linked (ionic and covalent) gelatin (G) and chitosan (CS) hydrogels was studied. The covalent cross-linking consists in the reaction between the carbonyl groups of glutaraldehyde with the free amine groups from the two polymers; the ionic cross-linking is based on sulfate anions interaction with protonated amine groups of the polymers solubilized in acetic acid. The structural and morphological characterization of the obtained hydrogels was performed using FT-IR and scanning electron microscopy (SEM). The influence of different parameters on the cross-linking density (indirectly assessed by water swelling capacity) and the ability to include hydrosoluble active principles such as the ratio between polymers (G/CS), the amount of ionic cross-linker, and the cross-linking time were investigated. The morphological and structural characteristics, mechanical stability, elasticity of the network, the interaction with aqueous weak alkaline solutions, and the capacity to load and release a model drug were analyzed for the obtained hydrogels. Rheological tests were performed to study the mechanical stability of the hydrogels and the results show, generally, elastic and stable networks. [ABSTRACT FROM PUBLISHER]

The production of a wide variety of biocompatible thin films by laser ablation deposed on the biomaterial substrates does not induce inflammatory response and repulsion by the immunization human body. Anodic potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used for the study of the electrochemical behavior of coated NiTi with chitosan through pulsed laser deposition (PLD) technique. Experiments were carried out using two different electrolytes: physiological 0.9 wt% NaCl solution (PS) and PS + hydrochloric acid (APS) at 37 ± 1 °C. In addition, scanning electron microscopy was employed to observe the surface morphology after maintaining in both electrolytes. The corrosion resistance was evaluated by means of the corrosion and passive corrosion currents. The electrochemical properties of the coated NiTi sample at the open circuit potential at different immersion time in PS and APS were studied by EIS. Equivalent circuits were used to model EIS data, in order to characterize samples' surface. [ABSTRACT FROM AUTHOR]

Abstract: In this study the influence of the experimental conditions on the obtention of polyelectrolyte multilayer capsules was investigated. Two ways of the simple coacervation method was used to obtain spherical capsules involving chitosan and hyaluronan, chitosan being inside the particle covered by a hyaluronan layer to increase the biocompatibility. The 1H-NMR spectroscopy confirmed a polyelectrolyte complex formation and the optical microscopy shows that the complexed capsules have good sphericity with average diameters ranging from 590 at 1550μm in the experimental conditions adopted. One can observe that in the acid medium the complexed capsules are much stable than the chitosan beads. The structures described provide a starting point for the design and fabrication of complexed capsules made of two biocompatible natural polymers with potential applicability in medical or pharmaceutical applications. Few diffusion experiments demonstrated that the complexed layer controls the diffusion of dextran included in the chitosan inner domain. [Copyright &y& Elsevier]