Cs Films Research Articles

Preparation of α-tocopherol-chitosan nanoparticles/chitosan/montmorillonite film and the antioxidant efficiency on sliced dry-cured ham

The aim of this work was to prepare a novel antioxidant film by incorporating α-tocopherol-chitosan nanoparticles (TOC-CSNPs) with chitosan/montmorillonite film (namely, TOC-CSNPs/CS/MMT), and investigate the antioxidant activity of TOC-CSNPs/CS/MMT film on sliced dry-cured ham in a period of 120 days at 4 °C. Positively charged TOC-CSNPs with the average sizes of 214 nm were prepared using TPP-initiated ionic gelation mechanism. The amount of TOC-CSNPs was optimized based on the changes of water vapor permeability (WVP), water solubility and swelling ratio of the film. The TOC-CSNPs/CS/MMT film showed 46.5% radical scavenging activity after 16 days of storage, which was 23 times and 27 times higher than that of CS/MMT and CS film, respectively. The antioxidant activity of TOC-CSNPs/CS/MMT film was evaluated by measuring the peroxide value (POV) and thiobarbituric acid reactive substances (TBARS) values of sliced dry-cured ham coated with the TOC-CSNPs/CS/MMT film-forming solutions. The results indicated that compared with the CS (0.42 g/100 g for POV, 0.65 mg/kg for TBARs) and CS/MMT (0.38 mg/kg for POV, 0.59 mg/kg for TBARs) films, the biceps femoris muscle of the sliced ham coated with TOC-CSNPs/CS/MMT film showed much lower values of POV (0.15 g/100 g) and TBARs (0.15 mg/kg) during 120 days of storage. These results provide a theoretical basis for developing efficient and long-term antioxidant approach, which is crucial for improving and enhancing the quality of food products.

A QCM humidity sensor constructed by graphene quantum dots and chitosan composites

A quartz crystal microbalance (QCM) humidity sensor based on graphene quantum dots-chitosan (GQDs-CS) sensitive film has been successfully fabricated in this work. The composite ratio of sensitive material and the coating quality of the sensitive film were optimized. The morphological and chemical properties of GQDs-CS composites were inspected via scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier Transform infrared spectroscopy (FT-IR). The results manifest that prepared QCM sensor exhibits high response sensitivity (a frequency shift of −3291 Hz at 95% RH), short response/recovery time (36 s/3 s), tiny humidity hysteresis (˜1.6% RH), and excellent reproducibility, reversibility and long-term stability. Additionally, the electroacoustic parameters of the QCM sensors were also investigated by means of the impedance analysis method. Based on dynamic and static analysis of the sensor, it is speculated that the introduction of GQDs into CS enhanced the mechanical stiffness of the CS film, which could effectively improve the performance of QCM sensor.

Preparation and characteristics of antibacterial chitosan films modified with N-halamine for biomedical application.

Several hydantoin derivatives and their N-halamine analogues were examined by spectroscopic methods (IR, 1H-NMR, 13C-NMR), elemental analysis (content of C, H, N), thermogravimetry (TGA), antibacterial tests and experiments of stability in aqueous solution. This research allowed the structural, thermal and antibacterial characteristics of obtained compounds. It was found, the thermal stability of hydantoins depends on their chemical structure and decreases when N-halamine moieties were introduced. In next step, synthesized biocides were added to the chitosan films. The antibacterial properties of received films were proved. It was found that after modification, the thermal stability of CS films decreases in most cases. The surface properties of obtained chitosan films before and after UV irradiation were investigated by means of contact angle measurements allowing the calculation of surface free energy. The chemical and structural changes during UV irradiation were studied by FTIR spectroscopy and SEM microscopy. The results indicated that the introduction of biocides to the CS material contribute to the photooxidation process. The degradation mechanism of obtained materials was proposed. The materials studied in this work may be used in various biomedical applications due to their confirmed biological activity.

Preparation of Assembled Carbon Soot Films and Hydrophobic Properties.

In this paper, a simple, inexpensive, and rapid method for the fabrication of controlled layer candle soot film has been reported by interface self-assembly and transferred method. The mechanism of candle soot self-assembly is explained and their morphology, elemental composition, optical, and wetting properties are characterized. The uniformity and thickness of prepared films especially depend on the concentration of candle soot mixed solution (alcohol and deionized water). The results show that the optimal concentration of candle soot solution is approximately ~0.2% wt/mL. In addition, the absorption spectra of the controlled-layer candle soot films are determined by the number of layers and the surface morphology. The hydrophobic properties of candle soot films are closely related to their layer number. When these films reach to the fourth layer, the water contact angle and roll-off angle are measured as 142° ± 2° and 6°, respectively. The controlled assembly CS films have the potential application in photo/electrocatalysis, solar cells, lithium-ion batteries, and water splitting.

Ursolic acid loaded-mesoporous bioglass/chitosan porous scaffolds as drug delivery system for bone regeneration

Bioglass scaffolds have great application potentials in orthopedics, and Ursolic acid (UA) can effectively promote in vivo new bone formation. Herein, we for the first time developed the mesoporous bioglass/chitosan porous scaffolds loaded with UA (MBG/CS/UA) for enhanced bone regeneration. The MBG microspheres with particle sizes of ~300 nm and pore sizes of ~3.9 nm were uniformly dispersed on the CS films. The mesoporous structure within the MBG microspheres and the hydrogen bonding between the scaffolds and UA drugs made the MBG/CS/UA scaffolds have controlled drug release performances. The as-released UA drugs from the scaffolds increased remarkably the alkaline phosphatase activity, osteogenic differentiation related gene type I collagen, runt-related transcription factor 2 expression, and osteoblast-associated protein expression. Moreover, the results of micro-CT images, histomorphological observations demonstrated that the MBG/CS/UA scaffolds improved new bone formation ability. Therefore, the MBG/CS/UA porous scaffolds can be used as novel bone tissue engineering materials.

Bioinspired enhancement of chitosan nanocomposite films via Mg-ACC crystallization, their robust, hydrophobic and biocompatible

Amorphous calcium carbonate/chitosan (ACC/CS) nanocomposite films containing Mg-ACC (0–100 wt%) are prepared by simple natural evaporation-induced assembly. The influence of Mg-ACC content on the mechanical properties as well as cross-section of ACC-CS nanocomposite films were systematically investigated. The nanocomposite films exhibit an excellent mechanical property at Mg-ACC contents of 80 wt% compared to ordinary calcium carbonate/chitosan composites. With content of Mg-ACC increasing, the mechanical properties of ACC-CS nanocomposite films were further increased, reaching a maximum when the content of Mg-ACC to 80 wt%. Strength and Young's modulus of the 80 wt% ACC-CS nanocomposite film reach 121.67 MPa and 31.96 GPa, respectively, which is 2.3 and 5.1 times higher than that of the pure CS film. After undergoing Mg-ACC crystal transformation when the Mg-ACC content is greater than 80 wt%, the smooth structure was transformed into crystal-like agglomerates, which deteriorates mechanical properties. Furthermore, the as-prepared nanocomposite films show excellent hydrophobicity and high biocompatibilities for boosting the growth of Cell-293T. In addition, we also proposed a physical model for the dispersion of Mg-ACC in CS matrix, which could better explain the enhancement of the mechanical properties of nanocomposite films. The above results provide a comprehensive understanding of the development of high-performance bionic nanocomposites loaded with high nanofillers.

Incorporation of lysozyme-rectorite composites into chitosan films for antibacterial properties enhancement

The demand for designing antibacterial materials was quite substantial in packing and biomedical materials fields. Chitosan had a wide utilization to satisfy this demand. In this study, by incorporating lysozyme (LY) – rectorite (REC) into chitosan films, the ultimately obtained hybrid films can own the enhanced antibacterial properties and still remains good mechanical properties. Scanning electron microscopy (SEM) images revealed that LY and REC could be homogeneously distributed in the CS films. X-ray photoelectron spectroscopy (XPS) and Energy-dispersive X-ray analysis (EDX) results verified that the LY-REC incorporation process was successful. Small angle X-ray diffraction (SAXRD) and Fourier transform infrared (FT-IR) spectra revealed that some intercalation reactions occurred between CS chains and REC. The hydrophobic properties of the CS films were increased by the addition of LY and REC, determined by water contact angle measurement. In comparison with CS films, the mechanical properties of the composite films after adding LY-REC were reduced by 27.58%, but still maintained high tensile strength. Besides, the antibacterial properties of the films could be enhanced by introducing LY-REC. This method exhibited great application value in the food packaging fields.

Optimized pH-responsive film based on a eutectic mixture-plasticized chitosan

Chitosan (CS, 2g/100mL)/curcumin 1g/100mL in acetic acid aqueous solution were used to prepare films to be used as food indicator. Microcrystalline cellulose (MCC) and a eutectic mixture (DES) were incorporated as reinforcing and plasticizing agents, respectively. The MCC content (133 mas%) and DES composition (7.93 mass%), based on CS dry mass, were optimized. The properties of the DES-plasticized film were compared to those for the unplasticized and glycerol (G)-plasticized CS films. The DES-plasticized film presented initial temperature of thermal decomposition at 267.7°C, dynamic glass transition at 149.3°C, water vapor permeability of 7.21×10−10gs−1m−1Pa−1, water solubility of 3.07% and stress at break of 20.1MPa. The incorporation of MCC contributed to increase the crystallinity of the composite films. Colorimetric tests, carried out in aqueous environments for the DES-plasticized film, revealed accentuated color changes, mainly at pHs higher than pH 8.

In vitro and in vivo evaluation of the chitosan/Tur composite film for wound healing applications

We have developed tourmaline/chitosan (Tur/CS) composite films for wound healing applications. The characteristics of composite films were studied by optical microscope, infrared spectra and X-ray diffraction. Tur particles were uniformly distributed in the CS film and the crystal structure of CS was not remarkably changed except the decrease of crystallinity. The influence of Tur on wound healing applications was characterized by modulating Tur concentrations in the Tur/CS composite film prepared by loading Tur powder into CS matrix with different proportion (0, 1/40 and 1/10). Then L929 cells were co-cultured on the composite films to access the cytotoxicity in vitro. Tur concentrations strongly influenced cell process extension. Tur/CS composite film with 1/40 mass ratio could promote the cell adhesion and proliferation. Fewer and shorter processes were observed at high Tur density. When the composite films were transplanted on porcine full-thickness burn wounds, histological results demonstrated that the Tur/CS group with 1/40 mass ratio had a significantly higher number of newly-formed and mature blood vessels, and fastest regeneration of dermis. Based on the observed facts these films can be tailored for their potential utilization in wound healing and skin tissue engineering applications.

MgAl layered double hydroxide/chitosan porous scaffolds loaded with PFTα to promote bone regeneration.

Poor bone formation remains a key risk factor associated with acellular scaffolds that occurs in some bone defects, particularly in patients with metabolic bone disorders and local osteoporosis. We herein fabricated for the first time layered double hydroxide-chitosan porous scaffolds loaded with PFTα (LDH-CS-PFTα scaffolds) as therapeutic bone scaffolds for the controlled release of PFTα to enhance stem cell osteogenic differentiation and bone regeneration. The LDH-CS scaffolds had three-dimensional interconnected macropores, and plate-like LDH nanoparticles were uniformly dispersed within or on the CS films. The LDH-CS scaffolds exhibited appropriate PFTα drug delivery due to hydrogen bonding among LDH, CS and PFTα. In vitro functional studies demonstrated that the PFTα molecules exhibited potent ability to induce osteogenesis of hBMSCs via the GSK3β/β-catenin pathway, and the LDH-CS-PFTα scaffolds significantly enhanced the osteogenic differentiation of hBMSCs. In vivo studies revealed significantly increased repair and regeneration of bone tissue in cranial defect model rats compared to control rats at 12 weeks post-implantation. In conclusion, the LDH-CS-PFTα scaffolds exhibited excellent osteogenic differentiation and bone regeneration capability and hold great potential for applications in defined local bone regeneration.

Manufacturing and mechanical, thermal and electrical characterization of graphene loaded chitosan composites

Abstract A detailed characterization of Graphene (Gr) loaded chitosan films was conducted in this study. Thermal characterization of Gr loaded CS films was made by using thermogravimetric analysis and thermal conductivity measurement. 1, 2, and 3 wt% loading of Gr into CS increased the thermal conductivity of CS by 25, 258 and 244%, respectively. The effect of Gr loading into CS on electrical resistivity properties of CS was determined by surface resistivity measurements. 1 wt% loading of Gr decreased the surface resistivity of CS film from 4.7 × 10 5 Ω/sq to 4.4 × 10 3 Ω/sq. Viscoelastic properties of CS–Gr composite film samples were analyzed by using dynamic mechanical analysis. Mechanical, morphological, crystallographic properties of composite films were determined by tensile tests, scanning electron microscopy (SEM) observations, and X-ray diffraction analyses, respectively. The storage modulus of CS was increased by 32% with 1 wt% Gr loading into CS. With the loading of 1 wt% of Gr, tensile strength and Young's modulus of CS film increased by 128%, and 52%, respectively. The hydrophilicity of the CS and CS–Gr composites films was examined by contact angle measurements.

Chitosan film loaded with silver nanoparticles—sorbent for solid phase extraction of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II)

The present study describes the ecofriendly method for the preparation of chitosan film loaded with silver nanoparticles (CS-AgNPs) and application of this film as efficient sorbent for separation and enrichment of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II). The stable CS-AgNPs colloid was prepared by dispersing the AgNPs sol in chitosan solution at appropriate ratio and further used to obtain a cast film with very good stability under storage and good mechanical strength for easy handling in aqueous medium. The incorporation of AgNPs in the structure of CS film and interaction between the polymer matrix and nanoparticles were confirmed by UV–vis and FTIR spectroscopy. The homogeneously embedded AgNPs (average diameter 29nm, TEM analysis) were clearly observed throughout the film by SEM. The CS-AgNPs nanocomposite film shows high sorption activity toward trace metals under optimized chemical conditions. The results suggest that the CS-AgNPs nanocomposite film can be feasibly used as a novel sorbent material for solid-phase extraction of metal pollutants from surface waters.

Observation of an eg-derived metallic band at the Cs/SrTiO3 interface by polarization-dependent photoemission spectroscopy

A metallic band having the dz2-symmetry was evidenced at the interface between a Cs film and the SrTiO3(001) substrate. The symmetry assignment was carried out with the dipole-transition selection rule, probed by polarization-dependent photoemission spectroscopy. The eg-derived state of the SrTiO3(001) crystal is likely to be a bonding state composed of Cs s-orbital and Ti d-orbital with the eg symmetry, as predicted theoretically.

Controlled formation of surface hydrophilicity enhanced chitosan film by layer-by-layer electro-assembly.

Several surface hydrophilicity enhanced chitosan, CS, films were controllably formed by using the layer-by-layer electro-assembly, LBLEA, method with varied voltages. Experimentally, an employed electrostatic generator was employed by taking its anode and cathode electrodes alternatively linking to the CS solution or silicon plate to form two opposite cycles corresponding to the electrostatic force, EF, enhancement or reduction, respectively. Wetting results showed that the water contact angle, θW, on those CS film surfaces was gradually reduced with the applied voltage increase, especially by EF reduction, e.g. the θW on 0V sample at about 55° and on 4kV EF-reduction formed sample at about 20°. AFM images comparison showed that the LBLEA process can control the surface structure for CS film. ATR-FTIR spectra comparison showed that the EF reduction process would reveal the C-O groups on CS film surface to enhance the hydrophilicity.

Water-responsive internally structured polymer-surfactant films on solid surfaces.

Water-insoluble films of oppositely charged polyion-surfactant ion "complex salts" (CS) are readily cast on solid surfaces from ethanolic solutions. The methodology introduces new possibilities to study and utilize more or less hydrated CS. Direct SAXS measurements show that the surface films are water-responsive and change their liquid crystalline structure in response to changes in the water activity of the environment. In addition to the classical micellar cubic and hexagonal phases, a rectangular ribbon phase and a hexagonal close-packed structure have now been detected for CS composed of cationic alkyltrimethylammonium surfactants with polyacrylate counterions. Added cosurfactants, decanol or the nonionic surfactant C12E5, yield additional lamellar and bicontinuous cubic structures. Images of the surfaces by optical and atomic force microscopy show that the films cover the surfaces well but have a more or less irregular surface topology, including "craters" of sizes ranging from a few to hundreds of micrometers. The results indicate possibilities to create a wealth of water-responsive structured CS films on solid surfaces.

Detection of some volatile organic compounds with chitosan-coated quartz crystal microbalance

A quartz crystal microbalance (QCM) electrode coated with Chitosan (Cs) film was used as a sensor for some volatile organic compounds (VOCs) such as aliphatic amines and alcohols. A homogeneous smooth thin films of Cs coating on the QCM electrode was prepared by drop casting method. The frequency shifts (Δf) of the QCM, due to adsorption of the VOCs under investigation, onto the Cs film were measured and were related to the analytes’ concentrations. Calibration curves were obtained with linear relationships between the Δf (Hz) and the analyte concentrations (mg L−1). The sensor showed good sensitivity, reproducibility, and reversibility. The influence of different temperatures on the vapor adsorption, of the VOCs onto the Cs film, was studied.

Chitosan and polyvinyl alcohol composite films containing nitrofurazone: preparation and evaluation.

The aim of this study was to insert nitrofurazone in a chitosan membrane to be used as a wound dressing. Several blend films using chitosan (Cs) and polyvinyl alcohol (PVA), containing nitrofurazone were prepared by means of casting/solvent evaporating technique. Different characteristics such as mechanical properties, water vapor transmission rate (WVTR), oxygen permeability (OP), swelling ability (SW), differential scanning calorimetric (DSC), drug release profiles and antibacterial activity of the films were investigated. The results showed that nitrofurazone decreased tensile strength, OP and SW of Cs films, while increased WVTR. Addition of PVA at any concentration improved mechanical properties, reduced WVTR, and increased OP and SW of nitrofurazone-loaded Cs films. The latter films showed higher activity against Pseudomonas aeruginosa than drug-free chitosan films. The presence of PVA improves many properties of Cs-nitrofurazone films and makes them more desirable as dressing material for burn wounds. Although nitrofurazone alone is ineffective against P. aeruginosa, it is able to increase antibacterial effect of chitosan in composite films.

An amperometric β-glucan biosensor based on the immobilization of bi-enzyme on Prussian blue–chitosan and gold nanoparticles–chitosan nanocomposite films

A novel β-glucan biosensor was fabricated by immobilizing β-glucanase (β-G) with glucose oxidase (GOD) on nano-Prussian blue–chitosan (PB–CS) and gold nanoparticles–chitosan (AuNPs–CS) composites. Both the PB–CS and AuNPs_CS film were directly electrodeposited on the surface of gold electrode. The morphology of the AuNPs–CS/PB–CS nanocomposites was characterized by scanning electron microscope (SEM). The electrochemical behavior of the resulting sensor was investigated using cyclic voltammetry (CV) and amperometry. It was found that PB–CS nanocomposite exhibited an excellent electrocatalytic reduction towards hydrogen peroxide at a low applied potential window. The synergistic effect of AuNPs–CS/PB–CS nanocomposites could remarkably improve the performances of the biosensor. Under optimal conditions, the biosensor showed a wide linear range of 6.25–93.75μM, with a correlation coefficient of 0.9991. The sensitivity at an applied potential of 0.0V was 100nAμM−1cm−2, with a detection limit of 1.56μM. The apparent Michaelis–Menten constant (Km) was found to be 1.0mM, showed a high affinity of the immobilizing β-G for β-glucan. The biosensor displayed a rapid response (within 10s) toward β-glucan, with a good selectivity and stability.

Evaluation of Cross-Linked Chitosan as Filler for Thermal Properties of Chitosan-Based Biocomposites

A series of cross-linked chitosan (XCs)-filled chitosan (Cs) matrix, with filler contents of 0 to 12 wt/v% were fabricated using a casting method. Thermal properties of the composites were examined using thermogravimetry (TG), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Addition of XCs to 10 wt/v% increased 2.7% on thermal properties of Cs film. Consequently, the glass transition temperature (Tg) is enhanced from 51 to 58°C for a similar composition of XCs. Results could be related to good interfacial interactions of Cs matrix and XCs filler through formation of interhydrogen bonds and electrostatic interactions.

Preparation and characterization of gadolinium-loaded PLGA particles surface modified with RGDS for the detection of thrombus

Thrombotic disease is a leading cause of death and disability worldwide. The development of magnetic resonance molecular imaging provides potential promise for early disease diagnosis. In this study, we explore the preparation and characterization of gadolinium (Gd)-loaded poly (lactic-co-glycolic acid) (PLGA) particles surface modified with the Arg-Gly-Asp-Ser (RGDS) peptide for the detection of thrombus. PLGA was employed as the carrier-delivery system, and a double emulsion solvent-evaporation method (water in oil in water) was used to prepare PLGA particles encapsulating the magnetic resonance contrast agent Gd diethylenetriaminepentaacetic acid (DTPA). To synthesize the Gd-PLGA/chitosan (CS)-RGDS particles, carbodiimide-mediated amide bond formation was used to graft the RGDS peptide to CS to form a CS-RGDS film that coated the surface of the PLGA particles. Blank PLGA, Gd-PLGA, and Gd-PLGA/CS particles were fabricated using the same water in oil in water method. Our results indicated that the RGDS peptide successfully coated the surface of the Gd-PLGA/CS-RGDS particles. The particles had a regular shape, smooth surface, relatively uniform size, and did not aggregate. The high electron density of the Gd-loaded particles and a translucent film around the particles coated with the CS and CS-RGDS films could be observed by transmission electron microscopy. In vitro experiments demonstrated that the Gd-PLGA/CS-RGDS particles could target thrombi and could be imaged using a clinical magnetic resonance scanner. Compared with the Gd-DTPA solution, the longitudinal relaxation time of the Gd-loaded particles was slightly longer, and as the Gd-load concentration increased, the longitudinal relaxation time values decreased. These results suggest the potential of the Gd-PLGA/CS-RGDS particles for the sensitive and specific detection of thrombus at the molecular level.