Uracha Ruktanonchai

Antibacterial effect of apatite-coated titanium dioxide for textiles applications.

An antibacterial activity of apatite-coated titanium dioxide (TiO2) against four types of bacteria (Staphylococcus aureus, Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), and Micrococcus luteus) was investigated. Its antibacterial performance was observed under black light, visible light, and dark conditions. The number of viable bacteria decreased with irradiation time and became most prominent at 24 hours. Distortion of bacterial cells by the nanoparticles was demonstrated by scanning electron microscopy. Apatite-coated TiO2 was fixed on cotton textiles by dip-coat technique, and the antimicrobial properties of corresponding fabrics were then investigated. The effect of irradiation source on antimicrobial activity of coated cotton fabrics was examined, wherein black-light irradiation demonstrated higher antibacterial activity than either visible-light irradiation or dark conditions. Microbial populations of coated cotton fabrics decreased with increasing irradiation intensity. Coated cotton fabrics have been shown to be nontoxic to human dermal fibroblasts. Our findings suggest that the presence of apatite-coated TiO2 shows antibacterial activity in the presence of black light or visible light, suggesting its potential use in reducing the risk of microorganism transmission for textile applications.

Characterization and mosquito repellent activity of citronella oil nanoemulsion

Encapsulated citronella oil nanoemulsion prepared by high pressure homogenization at varying amounts of surfactant and glycerol, was studied in terms of the droplet size, stability, release characteristics and in vivo mosquito protection. Transparent nanoemulsion can be obtained at optimal concentration of 2.5% surfactant and 100% glycerol. Physical appearance and the stability of the emulsion were greatly improved through an addition of glycerol, owing to its co-solvent and highly viscous property. The increasing emulsion droplet increased the oil retention. The release behavior could be attributed to the effect of droplet size and concentrations of surfactant and glycerol. By fitting to Higuchis equation, an increase in glycerol and surfactant concentrations resulted in slow release of the oil. The release rate related well to the protection time where a decrease in release rate can prolong mosquito protection time.

Influence of curcumin-loaded cationic liposome on anticancer activity for cervical cancer therapy.

The delivery of curcumin has been explored in the form of liposomal nanoparticles to treat various cancer cells. Since curcumin is water insoluble and an effective delivery route is through encapsulation in liposomes, which were modified with three components of DDAB, cholesterol and non-ionic surfactant. The purpose of this study was to establish a critical role of DDAB in liposomes containing curcumin at cellular response against two types of cell lines (HeLa and SiHa). Here, we demonstrate that DDAB is a potent inducer of cell uptake and cell death in both cell lines. The enhanced cell uptake was found on DDAB-containing liposome, but not on DDAB-free liposome. However, the cytotoxicity of DDAB-containing liposomes was high and needs to be optimized. The cytotoxicity of liposomal curcumin was more pronounced than free curcumin in both cells, suggesting the benefits of using nanocarrier. In addition, the anticancer efficiency and apoptosis effect of the liposomal curcumin formulations with DDAB was higher than those of DDAB-free liposomes. Therefore curcumin loaded liposomes indicate significant potential as delivery vehicles for the treatment of cervical cancers.

Development of Meloxicam-Loaded Electrospun Polyvinyl Alcohol Mats as a Transdermal Therapeutic Agent

This study reports on the use of electrospun polyvinyl alcohol (PVA) nanofiber mats loaded with meloxicam (MX) as a transdermal drug delivery system. The amounts of MX loaded in the base PVA solution (10% w/v solution) were 2.5, 5, 10 and 20% weight, based on the dry weight of PVA (% wt). The average diameters of these fibers ranged from 121–185 nm. In all concentrations of MX loaded in spun PVA fiber mats, an amorphous nanodispersion of MX with PVA was obtained. Both the degree of swelling and the weight loss of the electrospun PVA mats were greater than those of the as-cast PVA films. The tensile strength of the as-spun fiber mats was lower than that of the as-cast PVA films, but the strain at the maximum of the as-spun fiber mats was about six times higher than that of the as-cast PVA films. The skin permeation flux of the MX permeated from MX-loaded as-spun PVA were significantly higher than from MX-loaded as-cast PVA films, and increased when the MX content in both MX-loaded as-spun PVA and MX-loaded as-cast PVA films was increased. Our research suggests a potential use for MX-loaded electrospun PVA mats as a transdermal drug delivery system.

Water-soluble β-cyclodextrin grafted with chitosan and its inclusion complex as a mucoadhesive eugenol carrier

Inclusion complex between water-soluble βCD-grafted chitosan derivatives (QCD-g-CS) and eugenol (EG) was investigated as a new type of mucoadhesive drug carrier. The QCD-g-CSs were synthesized with various βCD moieties ranging from 5 to 23%. Spontaneous inclusion complex of these derivatives and EG were found and confirmed by FTIR and simulation study. Self-aggregated formations of QCD-g-CS were found, according to fluorescence and TEM studies, where the formations were preferable for QCD11g-CS and QCD5-g-CS. EG can be included in both βCD hydrophobic cavity and hydrophobic core of QCD-g-CS self-aggregates, resulting in varying entrapment efficiencies. Degree of QCD substitution on QCD-g-CS plays an important role on their physical properties, due to steric hindrance. The QCD11-g-CS showed excellent mucoadhesion, compared to the QCD5-g-CS and QCD23-g-CS. Moreover, the inclusion complex between QCD-g-CS and EG tend to express higher antimicrobial activities against Candida albicans, Streptococcus oralis and Streptococcus mutans, than the native QCD-g-CS.

Rheological and morphological characterizations on physical stability of gamma-oryzanol-loaded solid lipid nanoparticles (SLNs).

In the present study, gamma-oryzanol was incorporated into glycerol behenate (Compritol 888 ATO) nanoparticles (SLNs) at 5 and 10% (w/w) of lipid phase. Increasing lipid phase concentration resulted in increased consistency and particle diameter of SLNs. Upon storage over 60 days at 4, 25 and 40 degrees C, the instability was observed by rheological analysis for all samples due to the formation of gelation. Rheological measurement revealed the increase in storage modulus and critical stress during storage at all temperatures. However, at 40 degrees C, the pronounced instability was observed from the highest increase in storage modulus and a formation of rod-like network structure from scanning electron micrographs. An increase in crystallinity, determined by differential scanning calorimetry, was also found during storage at all temperatures, confirming the instability of SLNs. Particle diameters and zeta potentials of both concentrations at all storage conditions failed to explain the observed instability. These investigations may help to develop formulations of solid lipid nanoparticles, which are optimized with respect to the desired rheological properties.

Incorporation methods for cholic acid chitosan-g-mPEG self-assembly micellar system containing camptothecin

A water-insoluble anticancer agent, camptothecin (CPT) was incorporated to a polymeric micelle carrier system preparing from cholic acid chitosan-grafted poly (ethylene glycol) methyl ether (CS-mPEG-CA). CS-mPEG-CA formed a core-shell micellar structure with a critical micelle concentration (CMC) of 7.08 microg/ml. Incorporation efficiency was investigated by varying physical incorporation method and initial drug loading. Among three incorporation methods (dialysis, emulsion and evaporation methods), an emulsion method showed the highest CPT incorporation efficiency. Increasing the initial CPT loading from 5 to 40%, the incorporation efficiency decreased. In all examined CPT-loaded CS-mPEG-CA micelles, 5% initial drug loading showed the highest drug incorporation efficiency. Release of CPT from the micelles was sustained when increasing the initial CPT loading. This indicates the importance of incorporation method and the initial drug loading to obtain the optimum particle size with high drug loading and sustained drug release. When compared to the unprotected CPT, CPT-loaded CS-mPEG-CA micelles were able to prevent the hydrolysis of the lactone group of the drug. This novel CS-mPEG-CA polymer presents considerable potential interest in the further development of CPT carrier.

Chemical and structural investigation of lipid nanoparticles: drug–lipid interaction and molecular distribution

Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of gamma-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812 as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the gamma-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance ((1)H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the (1)H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of gamma-oryzanol inside the lipid nanoparticles, the (1)H-NMR revealed that the chemical shifts of the liquid lipid in gamma-oryzanol loaded systems were found at rather higher field than those in gamma-oryzanol free systems, suggesting incorporation of gamma-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of gamma-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of gamma-oryzanol and lipids (solid and liquid) inside the lipid nanoparticle systems are proposed.

Hydroxyapatite-hybridized chitosan/chitin whisker bionanocomposite fibers for bone tissue engineering applications

Biomimetic nanofibrous scaffolds derived from natural biopolymers for bone tissue engineering applications require good mechanical and biological performances including biomineralization. The present work proposes the utility of chitin whisker (CTWK) to enhance mechanical properties of chitosan/poly(vinyl alcohol) (CS/PVA) nanofibers and to offer osteoblast cell growth with hydroxyapatite (HA) mineralization. By using diacid as a solvent, electrospun CS/PVA nanofibrous membranes containing CTWK can be easily obtained. The dimension stability of nanofibrous CS/PVA/CTWK bionanocomposite is further controlled by exposing to glutaraldehyde vapor. The nanofibrous membranes obtained allow mineralization of HA in concentrated simulated body fluid resulting in an improvement of Youngs modulus and tensile strength. The CTWK combined with HA in bionanocomposite is a key to promote osteoblast cell adhesion and proliferation. The present work, for the first time, demonstrates the use of CTWKs for bionanocomposite fibers of chitosan and its hydroxyapatite biomineralization with the function in osteoblast cell culture. These hydroxyapatite-hybridized CS/PVA/CTWK bionanocomposite fibers (CS/PVA/CTWK-HA) offer a great potential for bone tissue engineering applications.

Increased dispersion and solubility of carbon nanotubes noncovalently modified by the polysaccharide biopolymer, chitosan: MD simulations

Abstract In order to explain the solubility of carbon nanotubes (CNT), including single walled CNTs, wrapped with chitosan of a 60% degree of deacetylation, MD simulations were applied to represent three chitosan concentrations, using two pristine CNTs (pCNT–pCNT), and one and two CNTs wrapped (pCNT–cwCNT and cwCNT–cwCNT). The CNT aggregation was observed in pCNT–pCNT and pCNT–cwCNT due to van der Waals interactions between tube–tube aromatic rings, and inter-CNT bridging by chitosan, respectively. At higher chitosan concentrations, such that most to all of CNTs were wrapped with chitosan, charge–charge repulsion was found to separate robustly the cwCNTs and lead to a well dispersed solution.