Thin Chitosan Layer Research Articles

Chiral Nanostructured Glycerohydrogel Sol-Gel Plates of Chitosan L- and D-Aspartate: Supramolecular Ordering and Optical Properties.

A comprehensive study was performed on the supramolecular ordering and optical properties of thin nanostructured glycerohydrogel sol-gel plates based on chitosan L- and D-aspartate and their individual components in the X-ray, UV, visible, and IR ranges. Our comparative analysis of chiroptical characteristics, optical collimated transmittance, the average cosine of the scattering angle, microrelief and surface asymmetry, and the level of structuring shows a significant influence of the wavelength range of electromagnetic radiation and the enantiomeric form of aspartic acid on the functional characteristics of the sol-gel materials. At the macrolevel of the supramolecular organization, a complex topography of the surface layer and a dense amorphous-crystalline ordering of polymeric substances were revealed, while at the nanolevel, there were two forms of voluminous scattering domains: nanospheres with diameters of 60-120 nm (L-) and 45-55 nm (D-), anisometric particles of lengths within ~100-160 (L-) and ~85-125 nm (D-), and widths within ~10-20 (L-) and ~20-30 nm (D-). The effect of optical clearing on glass coated with a thin layer of chitosan L-(D-)aspartate in the near-UV region was discovered (observed for the first time for chitosan-based materials). The resulting nanocomposite shape-stable glycerohydrogels seem promising for sensorics and photonics.

Triggered protein release from calcium alginate/chitosan gastro-resistant capsules

This work aimed to develop gastro-resistant capsules, based on alginate (Alg), as an oral delivery system for enhanced bioavailability of proteins. Bovine Serum Albumin (BSA), selected as a model protein, has been encapsulated inside calcium alginate capsules, which have been coated with a thin layer of chitosan (CHT) to improve its robustness and delivery profile. BSA and sodium alginate aqueous mixtures were characterized by optical microscopy and dynamic light scattering, suggesting that BSA and sodium alginate form water-in-water coacervate droplets by ionic complexation. Encapsulation of BSA-Alg colloidal dispersions was performed by introducing the BSA-Alg mixtures in CaCl2 solutions. Thus, calcium alginate capsules were formed, which were subsequently coated with CHT. Encapsulation of BSA achieved ≈99 % efficiency, the water content of capsules was ≈95 wt % and the amount of chitosan coating in wet capsules was <0.032 wt %. The stability of the capsules and the release of BSA were studied by several in vitro techniques, in simulated gastric and intestinal fluids. The addition of CHT as a coating material greatly improved the performance of the capsules, compared to that of capsules without CHT. The results of calcium alginate-chitosan capsules showed that they are stable in water at neutral pH and remain almost intact in simulated gastric fluid, but rapidly disintegrate when further treated with simulated intestinal fluid. These results demonstrated that calcium alginate-chitosan capsules can protect proteins from harsh gastric conditions and release their content at intestinal pH, demonstrating their potential application in the field of oral protein delivery.

ENCAPSULATION OF VITAMIN D IN THE EXINE-ALGINATE-CHITOSAN MICROCAPSULE SYSTEM

The insufficiency of vitamin D, resulting from inadequate exposure to sunlight and/or insufficient dietary intake, remains a major public health concern on a global scale. In this study, vitamin D2 and D3 were microencapsulated using sporopollenin exine microcapsules extracted from Cedrus libani pollens. After loading vitamin D into the microcapsules, they were coated with chitosan, an edible, biocompatible, and mucoadhesive polysaccharide, and alginate (a food additive agent coded E401). Exine microcapsules were extracted by microwave irradiation-assisted chemical method, and structural and morphological examination of exine structures was performed by FT-IR, TGA, SEM, and SEM-EDX analyses. After loading vitamin D into microcapsules in an ethanol medium, the loaded microcapsules were immobilised into the alginate matrix in a calcium chloride solution. D2 and D3 were loaded into 100 mg of sporopollenin exine microcapsules, resulting in loading efficiencies of 31.5 mg and 16.0 mg, respectively. The vitamin D release performance of the microcapsules was examined depending on time and temperature after they were coated with a thin chitosan layer. The release of the highest amount of vitamin D2 and D3 occurred at a temperature of 37°C. Encapsulating vitamin D molecules in chitosan and alginate creates a barrier against degrading environmental conditions, which helps prevent the loss of vitamin D biological activity. This can improve vitamin D dietary supplements' storage, preservation, and marketing requirements.

Transfer-Printed Environmental-Friendly Anisotropic Filter with Laser-Controlled Micropores for Efficient Oil/Water Separation

Water is indispensable for sustaining life on Earth. Oil–water mixtures/or emulsions from industrial waste and other sources are a serious environmental concern for both human beings and aquatic life. Specially treated meshes and textiles with opposing wettability for oil–water separation have been widely reported as a solution to this challenge. Nonetheless, such membranes are hindered by certain drawbacks, including high manufacturing costs, usage of harmful chemicals, and lack of diverse applicability. Here, we report a facile method to fabricate Janus oil–water separation membrane with a controllable pore structure that has a unique directional flux rate. The superhydrophobic (SHB) layer of the membrane is formed by transfer-printing (TP) carbon soot particles onto a polydimethylsiloxane (PDMS)-coated paper surface. Meanwhile, a spin-coated thin layer of chitosan on the other side of the film served as a hydrophilic (SHL) and underwater oleophobic face. A pulsed laser beam is used to produce micropores with conical structures. The separation ability of the membrane for both light oil–water and heavy oil–water mixtures is thoroughly investigated. Moreover, the significance of the pore shape and the size is also elucidated. The flexible Janus membrane showed high thermal stability and ideal (i.e., 99.8%) separation efficiency. The membrane can be produced over a 151 cm2 size range. Besides having flexibility and superior performance, the fabricated membrane is environmentally friendly and economically viable. This work establishes a scalable basis for efficient and low-cost oil/water membranes from non-porous substrates.

Preparation of slow-release regulated Rs-198 bilayer microcapsules and application of its lyophilized bacterial inoculant on Capsicum annuum L. under salt stress

The survival adaptation of bacteria in saline soil is poor. The bilayer microcapsules were prepared by secondary embedding of monolayer sodium alginate (NaAlg) - bentonite (Bent) - sodium carboxymethylcellulose (CMC) microcapsules wrapped with plant growth promoting rhizobacteria (PGPR) Pseudomonas putida Rs-198 by chitosan solution to promote the synergistic effect of bilayer microencapsulation and PGPR. The characterization of the Rs-198 bilayer microcapsules showed that the amino and carboxyl groups were cross-linked and a thin layer of chitosan was formed on the outside of the microcapsule. The bilayer microcapsule (Ch-d) with a chitosan concentration of 0.8 wt% and pH 6 showed a slow release of bacteria with a maximum release of 6.06 × 109 cfu/g on the 7th day. The viable bacteria of Ch-d increased by 4.42% after 60 days of storage compared with monolayer microcapsules. The 0.9 wt% l-cysteine, 10 wt% glycerinum, 10 wt% trehalose and 12 wt% soluble starch were added as bacterial protective agents during the process of preparing the Ch-d lyophilized bacterial inoculant (Ch-d LBI). Pot experiments showed that Ch-d LBI exhibited better growth promotion of Capsicum annuum L. under salt stress. Therefore, the bilayer microcapsule as slow-release bacterial inoculant is a potential alternative for sustainable agriculture.

Batch and column adsorption of reactive dye by eggshell powder–chitosan gel core-shell material

In this study, eggshell powder-chitosan gel (EPCG) material was synthesized and tested as an adsorbent for two commercial reactive dyes in batch and dynamic modes. The EPCG material was a novel core-shell material in which the eggshell core particles were coated by a thin layer of chitosan. SEM images of dried EPCG powder showed a porous structure of the surface. In adsorption batch tests, Langmuir and Freundlich equations well described the adsorption isotherms with a maximum capacity of 2.3 mg/g at pH 4 and equilibrium time of 60 min (r 2 > 0.98). The adsorption process followed pseudo-second-order kinetics. Adsorption behaviour of EPCG toward the reactive dyes in fixed-bed adsorber was better described by the Clark model (r 2 > 0.92) than by the Bohart – Adam model (r 2 > 0.82). These results suggest that EPCG, as an environment-friendly material produced from waste eggshell, is very promising for wastewater treatment applications.

Chitosan Coating of TiO2 Nanotube Arrays for Improved Metformin Release and Osteoblast Differentiation.

BackgroundIneffective integration has been recognized as one of the major causes of early orthopedic failure of titanium-based implants. One strategy to address this problem is to develop modified titanium surfaces that promote osteoblast differentiation. This study explored titanium surfaces modified with TiO2 nanotubes (TiO2 NTs) capable of localized drug delivery into bone and enhanced osteoblast cell differentiation.Materials and MethodsBriefly, TiO2 NTs were subjected to anodic oxidation and loaded with Metformin, a widely used diabetes drug. To create surfaces with sustainable drug-eluting characteristics, TiO2 NTs were spin coated with a thin layer of chitosan. The surfaces were characterized via scanning electron microscopy, atomic force microscopy, and contact angle measurements. The surfaces were then exposed to mesenchymal bone marrow stem cells (MSCs) to evaluate cell adhesion, growth, differentiation, and morphology on the modified surfaces.ResultsA noticeable increase in drug release time (3 days vs 20 days) and a decrease in burst release characteristics (85% to 7%) was observed in coated samples as compared to uncoated samples, respectively. Chitosan-coated TiO2 NTs exhibited a considerable enhancement in cell adhesion, proliferation, and genetic expression of type I collagen, and alkaline phosphatase activity as compared to uncoated TiO2 NTs.ConclusionTiO2 NT surfaces with a chitosan coating are capable of delivering Metformin to a bone site over a sustained period of time with the potential to enhance MSCs cell attachment, proliferation, and differentiation.

Study of nitrogen implantation in Ti surface using plasma immersion ion implantation & deposition technique as biocompatible substrate for artificial membranes.

The present investigation reports the modification of Ti substrates by a plasma technique to enhance their physio-chemical properties as biocompatible substrates for the deposition of artificial membranes. For that purpose, nitrogen ions are implanted into Ti substrate using the plasma immersion ion implantation & deposition (PIII&D) technique in a capacitively coupled radio frequency plasma. The plasma was characterized using optical emission spectroscopy, together with radio frequency compensated Langmuir probe, while the ion current towards the substrate was measured during the implantation process using an opto-electronic device. X-ray photoelectron spectroscopy (XPS) was used for chemical analysis of the surface, confirming the presence of δ-TiN. The penetration depth of the nitrogen ions into the Ti substrate was measured using secondary ions mass spectroscopy (SIMS) while the morphological changes were observed using atomic force microscopy (AFM). A calorimetric assay was used to prove that the TiN samples maintain the biocompatibility of the untreated Ti surface with its native oxide layer. The ion implantation increases the load bearing ability of Ti surface by the formation of α-Ti(N) and δ-TiN phases on the sub-surface of Ti, and maintains the bio compatibility of Ti surface. After the plasma treatment a thin layer of chitosan (CH) was deposited in order to provide a moisturizing matrix for the artificial membrane of 1,2-dipalmitoyl-sn-3- phosphor glycerocholine (DPPC). The CH and subsequently the DPPC were deposited on the plasma deposited TiN substrate by using physical vapor deposition. The formation of artificial membranes was confirmed by AFM, measuring the topography at different temperatures and performing force curves.

Environmentally Friendly Surface Treatment of Wool Fiber with Plasma and Chitosan for Improved Coloration with Cochineal and Safflower Natural Dyes

In this study, the effect of surface modification of wool fiber with oxygen plasma and chitosan (PC) on the color strength of the samples dyed with cochineal and safflower natural dyes has been studied. According to colorimetric measurements, plasma and chitosan treatments resulted in notable improvements in dyeability of wool fibers. The plasma and chitosan-treated wool sample could be dyed in less time and at lower temperature compared with untreated one. The dyebath pH had a prominent effect on color strength, which showed that the electrostatic force has an important role in dye adsorption. The optimum pH for maximum dye absorption was 3.6. The fastness properties, tensile strength, and elongation at break of dyed wool were improved after PC treatment. Scanning electron microscopy (SEM) images and ATR-FTIR analysis proved the coating of wool scales with a uniform thin layer of chitosan, which caused the improved dyeability of wool fibers with safflower and cochineal.

Fabrication of chitosan-coated porous polycaprolactone/strontium-substituted bioactive glass nanocomposite scaffold for bone tissue engineering.

In the present study, porous (about 70 vol%) nanocomposite scaffolds made of polycaprolactone (PCL) and different amounts (0 to 15 wt%) of 45S bioactive glass (BG) nanoparticles (with a particle size of about 40 nm) containing 7 wt% strontium (Sr) were fabricated by solvent casting technique for bone tissue engineering. Then, a selected optimum scaffold was coated with a thin layer of chitosan containing 15 wt% Sr-substituted BG nanoparticles. Several techniques such as X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), tensile test, and water contact angle measurement were used to characterize the fabricated samples. In vitro experiments including degradation, bioactivity, and biocompatibility (i.e., cytotoxicity, alkaline phosphate activity, and cell adhesion) tests of the fabricated scaffold were performed. The biomedical behavior of the fabricated PCL-based composite scaffold was interpreted by considering the presence of the porosity, Sr-substituted BG nanoparticles, and the chitosan coating. In conclusion, the fabricated chitosan-coated porous PCL/BG nanocomposite containing 15 wt% BG nanoparticles could be utilized as a good candidate for bone tissue engineering.

Chitosan Cross-Linked Bio-based Antimicrobial Polypropylene Meshes for Hernia Repair Loaded with Levofloxacin HCl via Cold Oxygen Plasma

Polypropylene (PP) large pore size nets have been most widely used implants for hernia repair. Nevertheless, the growth of bacteria within PP mesh pores after operation is a major reason of hernia recurrence. Secondly, pre-operative prophylaxis during mesh implantation has failed due to the hydrophobic nature of PP meshes. Herein, chitosan cross-linked and levofloxacin HCl incorporated, antimicrobial PP mesh devices were prepared using citric acid as a bio-based and green cross-linking agent. The inert PP mesh fibers were surface activated using O2 plasma treatment at low pressure. Then, chitosan of different molecular weights (low and medium weight) were cross-linked with O2 plasma activated surfaces using citric acid. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy confirmed that chitosan was cross-linked with O2 plasma-treated PP mesh surfaces and formed a thin layer of chitosan and levofloxacin HCl on the PP mesh surfaces. Moreover, antimicrobial properties of chitosan and levofloxacin HCl-coated PP meshes were investigated using an agar plate release method. The coated PP meshes demonstrated excellent antimicrobial inhibition zone up to 10 mm. Thus, modified PP meshes demonstrated sustained antimicrobial properties for six continuous days against Staphylococcus aureus (SA) and Escherichia coli (EC) bacteria.

Hierarchical magnetic/chitosan/graphene oxide 3D nanostructure as highly effective adsorbent

The significance of contamination management is obviously the cornerstone of the human future. Indeed, to find an efficient and economic approach to manage the dyeing effluents, combined treatment processes of adsorption and filtration for hierarchical magnetic/chitosan/graphene oxide(MCGO) 3D nanostructure adsorbent were controlled. The aim of this work is particularly to control the growth of ferrihydrite and consequently the morphology of hierarchical 3D nanostructured MCGO by a one-step facile ultrasonic chemical technique. In addition, this adsorbent is used to remove Disperse Blue 367(DB367) from dyeing effluent. Actually, the main matrix of magnetite(nanoparticles) and goethite(hollow nanorods) both coated with a thin layer of chitosan and dispersed with GO(layers) was grown. In addition, the growth mechanisms were also discussed. Eventually, the synthesized MCGO adsorbent has saturation magnetization of 120.06emu/g and an excellent DB367 adsorption capacity of 298.27mg/g in 30min. The endothermic nature of DB367 adsorption fits the pseudo-second order model with 16.26gmg−1min−1.

Nanomechanics of pH-Responsive, Drug-Loaded, Bilayered Polymer Grafts.

Stimuli-responsive polymer films play an important role in the development of smart antibacterial coatings. In this study, we consider complementary architectures of polyelectrolyte films, including a thin chitosan layer (CH), poly(acrylic acid) (PAA) brushes, and a bilayer structure of CH grafted to PAA brushes (CH/PAA) as possible candidates for targeted drug delivery platforms. Atomic force microscopy (AFM) was employed to study the structure-mechanical property relationship for these mono- and bi-layered polymer grafts at pH 7.4 and 4.0, corresponding to physiological and biofilm formation conditions, respectively. Herein, the surface interactions between polymer grafts and the negatively charged silica colloid attached to an AFM lever are considered as representative interactions between the antibacterial coating and a bacteria/biofilm. The bilayered structure of CH/PAA showed significantly reduced adhesive interactions in comparison to pure CH but slightly higher interactions in comparison to PAA films. Among PAA and CH/PAA films, upon grafting CH over the PAA brushes, the normal stiffness increased by 10-fold at pH 7.4 and 20-fold at pH 4.0. Notably, the study also showed that the addition of an antibiotic drug such as multicationic Tobramycin (TOB) impacts the mechanical properties of the antibacterial coatings. Competition between TOB and water molecules for the PAA chains is shown to determine the structural properties of PAA and CH/PAA films loaded with TOB. At high pH (7.4), the TOB molecules, which remain multicationic, strongly interact with polyanionic PAA, thereby reducing the film's compressibility. On the contrary, at low pH (4.0), the water molecules preferentially interact with TOB in comparison to uncharged PAA chains and, upon TOB release, results in a stronger film collapse together with an increase in adhesive interactions between the probe, the surface, and the elastic modulus of the film. The bacterial proliferation on these platforms when compared to the measured mechanical properties shows a direct correlation; hence, understanding nanomechanical properties can provide insights into designing new antibacterial polymer coatings.

Preparation and characterization of a novel water soluble amino chitosan (amino-CS) derivative for facilitated transport of CO2

With the goal of obtaining a water soluble polymeric carrier for preparation of fixed facilitated transport membranes, a water soluble amino containing chitosan derivative was prepared through Michael-addition reaction between chitosan and ethyl acrylate followed by amidation of the ester groups with an appropriate diamine. This derivative was characterized using 1H-NMR spectroscopy. Then, facilitated transport membranes were prepared by casting a thin layer of chitosan derivative/poly(vinyl alcohol) blend on a porous polysolfune support; and the effect of fixed carrier’s content, feed temperature and feed pressure on the CO2 permeance, and CO2/CH4 selectivity of produced membranes were studied. A facilitated transport mechanism for CO2 through this membrane was concluded.

Wound dressing based on chitosan/hyaluronan/nonwoven fabrics: Preparation, characterization and medical applications

Thin layers of chitosan (positively charged)/sodium hyaluronate (negatively charged)/nonwoven fabrics were constructed by polyelectrolyte multilayer pad-dry-cure technique. Pure chitosan (CS) was isolated from shrimp shell and immobilized onto nonwoven fabrics (NWFs) using citric acid (CTA) as cross linker and solvent agents through a pad-dry-cure method. The prepared thin layer of chitosan citrate/nonwoven fabrics (CSCTA/NWFs) were consequently impregnated with hyaluronan (CSCTA/HA/NWFs) in the second path through a pad-dry-cure method. Chitosan/hyaluronan/nonwoven fabrics wound dressing was characterized by different techniques such as FTIR-ATR, TGA and SEM. The antibacterial activity and the cytotoxicity of the dressing sheets were evaluated against Escherichia coli (E. coli) and Streptococcus aureus (S. aureus), mouse fibroblast (NIH-3T3) and keratinocytes (HaCaT) cell lines, respectively. The cell-fabrics interaction was also investigated using fluorescence microscope, based on live/dead staining assay of 3T3 cells. The healing properties of the new wound dressing were evaluated and compared with the control sample.

Chitosan-coated alginate tissue scaffold constructed by three-dimensional plotting technique used for drug and cell delivery

Event Abstract Back to Event Chitosan-coated alginate tissue scaffold constructed by three-dimensional plotting technique used for drug and cell delivery Hsin-Yi Lin1 and Tsang-Wen Chang1 1 National Taipei University of Technology, Chemical Engineering and Biotechnology, Taiwan Introduction: It’s essential that the hydrogel carrier systems for drug and cell delivery be made in mild conditions quickly enough to prevent excessive loss of the drugs and cells they carry. Alginate solution can quickly form hydrogel in the presence calcium ions but the hydrogel is highly hydrophilic and degrades quickly in the presence of monovalent ions. Chitosan hydrogel is more hydrophobic and degrades more slowly compared to alginate. However, harmful chemicals are used in the process of making chitosan hydrogel and prevent chitosan from being used to encapsulate living cells. The two materials were combined to make a better cell/drug delivery tissue scaffold. Alginate hydrogel fibers containing bone cells and diclofenac, an anti-inflammatory drug, were constructed into 3D scaffolds and coated with a layer of chitosan hydrogel. We hypothesized that the alginate hydrogel could shield the embedded cells from the acid/base used during the chitosan coating processes. The chitosan coating was then expected to better preserve diclofenac during the scaffold making and to slow down diclofenac release during cell culture. Materials and Methods: The scaffolds were constructed by the three-dimensional (3D) plotting apparatus. In brief, an alginate solution containing osteoblasts and diclofenac was extruded into a calcium chloride+ chitosan acetic acid solution. The alginate formed hydrogel fibers with a thin layer of chitosan coating. The fibers were built layer by layer into a 3D scaffold and quickly neutralized in NaOH before rinsing (saline, pH=7). The cell/diclofenac-containing alginate scaffolds coated with chitosan (A/C) were co-cultured with macrophage cells in a-MEM containing lipopolysaccharide (LPS). LPS stimulates macrophages to release inflammatory species that are harmful to the cells. Diclofenac was known to inhibit macrophage cells from producing the inflammatory species. The cells and drug in 3D-printed plain alginate scaffolds (A) were used as control. The drug loading and release efficacies and the performance of the cells in the scaffolds were examined. Results and Discussion: A layer of chitosan was successfully coated onto the alginate hydrogel fibers of the tissue scaffold built. Chitosan fluoresced green (Ex=488nm) and the coating could be distinguished using scanning electron microscopy (Fig1). Also the cells embedded in A/C were viable after the chitosan-coating process. The chitosan coating was able to slow down the release of diclofenac from the alginate hydrogel. More diclofenac remained in A/C than in A after the post-processing steps were completed (Fig2). A/C carried more diclofenac and released it in a more sustainable fashion than A. As a result the concentrations of inflammatory species from macrophages co-cultured with A/C were significantly lower than those from macrophages co-cultured with A. Osteoblasts embedded in A/C hence grew faster, had higher alkaline phosphatase activity and mineralized more extensively (Fig2). Conclusion: A better cell/drug-containing tissue scaffold was developed by coating a layer of chitosan on the fibers of a 3D plotted alginate scaffold that contained diclofenac and cells. The cells inside the alginate hydrogel survived the harmful chemicals during chitosan coating and the coating then significantly enhanced the scaffold’s drug loading and release efficacies. Ministry of Science and Technology grand: MOST-2221-E-027-095 Keywords: Tissue Engineering, Drug delivery, 3D scaffold, Bone repair Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Biomaterials in constructing tissue substitutes Citation: Lin H and Chang T (2016). Chitosan-coated alginate tissue scaffold constructed by three-dimensional plotting technique used for drug and cell delivery. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.01752 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Hsin-Yi Lin Tsang-Wen Chang Google Hsin-Yi Lin Tsang-Wen Chang Google Scholar Hsin-Yi Lin Tsang-Wen Chang PubMed Hsin-Yi Lin Tsang-Wen Chang Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Deposition of Chitosan Layers on NiTi Shape Memory Alloy

Abstract The NiTi shape memory alloys have been known from their application in medicine for implants as well as parts of medical devices. However, nickel belongs to the family of elements, which are toxic. Apart from the fact that nickel ions are bonded with titanium into intermetallic phase, their presence may cause allergy. In order to protect human body against release of nickel ions a surface of NiTi alloy can be modified with use of titanium nitrides, oxides or diamond-like layers. On the one hand the layers can play protective role but on the other hand they may influence shape memory behavior. Too stiff or too brittle layer can lead to limiting or completely blocking of the shape recovery. It was the reason to find more elastic covers for NiTi surface protection. This feature is characteristic for polymers, especially, biocompatible ones, which originate in nature. In the reported paper, the chitosan was applied as a deposited layer on surface of the NiTi shape memory alloy. Due to the fact that nature of shape memory effect is sensitive to thermo and/or mechanical treatments, the chitosan layer was deposited with use of electrophoresis carried out at room temperature. Various deposition parameters were checked and optimized. In result of that thin chitosan layer (0.45µm) was received on the NiTi alloy surface. The obtained layers were characterized by means of chemical and phase composition, as well as surface quality. It was found that smooth, elastic surface without cracks and/or inclusions can be produced applying 10V and relatively short deposition time - 30 seconds.

Enhancing the performance and antifouling properties of nanoporous PES membranes using microwave-assisted grafting of chitosan

In this work, we have tried to improve the surface and antifouling properties of polyethersulfone (PES) membranes coated by a thin layer of chitosan. Acrylamide (AAm) as a grafting agent and microwave-assisted grafting as a physical procedure were employed to grafting of the chitosan thin layer without using any chemical initiator. Different acrylamide concentrations (1.8, 3 and 4.2wt.%), irradiation times (0, 10, 30 and 60s) as well as irradiation powers (180, 360 and 520W) were employed. The modified membranes showed an outstanding antifouling property for bovine serum albumin (BSA) in some conditions of preparation. The separation properties of the thin film composite membranes for ion solutions (NaCl, Na2SO4 and MgCl2) increased and changed. Water contact angle measurement, ATR-IR apparatus, SEM, AFM and membrane filtration set-up were used for supporting the results. We used Taguchi designs to analyze many factors with few runs.

Carvacrol affects interfacial, structural and transfer properties of chitosan coatings applied onto polyethylene

Different chitosan coating solutions were tested with the aim of investigating their adhesion and wettability onto polyethylene film to improve packaging performance and provide antimicrobial properties. Surface wetting kinetics was monitored by contact angle measurements. Addition of ethanol and carvacrol improved wettability and adhesion of the thin chitosan layer. Structure, water vapour, O2, CO2 and air permeabilities of self supported chitosan films and coated polyethylene were determined. The formation of a thin chitosan layer on polyethylene improved gas barrier properties decreasing the Permeability Coefficient for oxygen and carbon dioxide (PO2, PCO2) from 100 to 10,000 times. Presence of carvacrol in the chitosan coating layer increased PO2, PCO2 and Pair by a factor of ten. Moreover, it influenced film microstructure. However chitosan was shown to be good gas barrier film in the dry state.

Effect of relative humidity on carvacrol release and permeation properties of chitosan based films and coatings

The influence of water vapour conditions on mass transport and barrier properties of chitosan based films and coatings were studied in relation to surface and structural properties. Water contact angles, material swelling, polymer degradation temperature, barrier properties (PO2, PCO2, WVP) and aroma diffusion coefficients were determined. The solvent nature and the presence of carvacrol influenced the surface and structural properties and then the barrier performance of activated chitosan films. Increasing RH from 0% to 100% led to a significant increase in material swelling. The plasticization effect of water was more pronounced at high humid environment, while at low RH the matrix plasticization was induced by carvacrol. The deposit of a thin chitosan layer on polyethylene decreased PO2 and PCO2 both in dry and humid conditions. The carvacrol release from the chitosan matrix was strongly influenced by RH. A temperature increase from 4 to 37°C also had an impact on carvacrol diffusivity but to a lesser extent than RH.