Krisana Siraleartmukul

Electrospray fabrication of doxorubicin-chitosan-tripolyphosphate nanoparticles for delivery of doxorubicin

This work focused on a new technique for the preparation of doxorubicin (DOX) loaded chitosan (CS) nanoparticles (DOX-CS) — formation by electrospray ionization in the presence of tripolyphosphate (TPP) as the stabilizer. The working distance, needle gauge, flow rate, stirring rate, electrospraying voltage and DOX to CS molar ratio were sequentially and individually optimized and found to be a 26 gauge needle, an applied voltage of 13 kV, a flow rate of 0.5 mL/h, a working distance of 8 cm and a stirring rate of 400 rpm. The incorporation of chemically unchanged DOX with the CS into the particles was ascertained by Fourier transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Under these optimized conditions, the DOX-CS particles were found to be nanoparticles of approximately 300–570 (dry particles) or 530–870 nm diameter (hydrated particles), with a PDI and SPAN polydispersity indices of 0.97–0.82 and 0.62–0.64, respectively, for initial DOX loading levels of 0.25–1%, as determined by SEM and particle size analyzer, respectively. Moreover, a high encapsulation efficiency (EE) of DOX into the nanoparticles was attained, ranging from 63.4 to 67.9% EE at 1 to 0.25% DOX loading. Finally, the in vitro DOX release behaviors of the DOX-CS particles revealed a prolonged release of DOX over at least seven hours.

Enhanced water-solubility and mucoadhesion of N,N,N-trimethyl-N-gluconate-N-homocysteine thiolactone chitosan.

A water-soluble chitosan with improved mucoadhesion was prepared by modifying 19.4% of the amine groups of chitosan to trimethylammonium and conjugation of gluconolactone (GLU) and homocysteine thiolactone (HT) onto the remaining amine groups of the chitosan backbone. The derived trimethyl-gluconate-HT-chitosan (TM-GN-HT-chitosan) was confirmed by Fourier Transform Infrared spectroscopy, NMR and thermogravimetric analysis. The total thiol and disulfide group level on the TM-GN-HT-chitosan were 17.96 ± 0.03 and 7.36 ± 0.03 μmol/g, respectively. The water solubility of the TM-GN-HT-chitosan conjugate was 79.0 ± 0.15%, more than that of TM-chitosan and chitosan, with an enhanced solubility over a broad pH range ranging from 85.6 ± 10.4% to 58.5±1.1% maximal solubility at pH 2 to 11. Finally, TM-GN-HT-chitosan showed a nearly ∼9.5-, 5.0- and 5.6-fold higher mucoadhesiveness than chitosan at pH 1.2, 4.0 and 6.4, respectively, and was optimal at pH 4.0.

Structure determination of diclofenac in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction data

The structure determination of diclofenac embedded in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction data is demonstrated. It reveals that sodium diclofenac, the starting material in the preparation of a controlled-release diclofenac-containing chitosan matrix, changes to diclofenac acid in space group C2/c in the matrix. Simple methods were employed for handling the sample to obtain X-ray powder diffraction data of sufficiently high quality for the determination of the crystal structure of diclofenac embedded in chitosan. These involved grinding and sieving several times through a micro-mesh sieve to obtain a suitable particle size and a uniformly spherical particle shape. A traditional technique for structure solution from X-ray powder diffraction data was applied. The X-ray diffraction intensities were extracted using Le Bails method. The structure was solved by direct methods from the extracted powder data and refined using the Rietveld method. For comparison, the single-crystal structure of the same drug was also determined. The result shows that the crystal structure solved from conventional X-ray powder diffraction data is in good agreement with that of the single crystal. The deviations of the differences in bond lengths and angles are of the order of 0.030 A and 0.639°, respectively.

Enhanced anti-topoisomerase II activity by mucoadhesive 4-CBS–chitosan/poly (lactic acid) nanoparticles

In this study, the biodegradable mucoadhesive 4-carboxybenzensulfonamide chitosan (4-CBS-chitosan)/poly (lactic acid) (PLA) nanoparticles were fabricated by the electrospray ionization technique for enhancing anti-topoisomerase II (Topo II) activity. The obtained (4-CBS-chitosan/PLA)-DOX nanoparticles were characterized using SEM, particle size analyzer. We emphasis on encapsulation efficiency, in vitro drug release behavior and also performed in vitro studies of Topo II inhibitory activity using gel electrophoresis. In addition, the cytotoxicity of the 4-CBS-chitosan/PLA nanoparticles using MTT assay was also studied. The mean particle size of spherical shaped (4-CBS-chitosan/PLA)-DOX is less than 300 nm. The DOX loaded 4-CBS-chitosan/PLA composite nanoparticles produced high entrapment efficiency of 85.8% and provided the prolonged release of DOX extended to 26 days and also still had strong Topo II inhibitory activity up to 77.4%. Overall, it was shown that 4-CBS-chitosan/PLA nanoparticles could be promising carriers for controlled delivery of anticancer drugs.

Mucoadhesive drug carrier based on functional-modified cellulose as poorly water-soluble drug delivery system

Abstract The purpose of this study was to design and characterise an oral mucoadhesive micellar drug carrier. In this regard, a mucoadhesive hydrophobic cationic aminocellulose was easily synthesised under mild homogeneous conditions with high yield. The cellulose derivative resulted in strongly improved mucoadhesive properties but was pH dependent. Furthermore, the hydrophobic anticancer drug camptothecin was successfully encapsulated into the mucoadhesive cellulose derivative micelles with spherical shape stability of 233 nm in diameter and low particle size distribution. The CPT-loaded nanocarriers provided high encapsulation efficiency about 86.4%. In vitro release, CPT-loaded cellulose derivative micelles showed a reduction in release rate compared with physically pure CPT solution. The release results also indicated that a sustained release of CPT to >80% over 4 d for pH 6.8 and 7.4. Therefore, mucoadhesive hydrophobic cationic aminocellulose micelles seem to be a promising carrier for various pharmaceutical applications especially for poorly water-soluble drug delivery system.

Polymeric materials and films in dentistry: An overview

Graphical abstract

Fabrication of Fiber Cement Using Tobacco Stalk Pulp from Agricultural Residue

The objective of this research is to study the feasibility of using fiber obtained from tobacco stalk as reinforcement fiber in the production of fiber cement through hydrothermal methods. The fiber cement samples are made of the mixtures of 50% of ASTM Type I ordinary Portland cement, 35% of milled sand, 10% of calcium carbonate powder and 5% of cellulose fiber (eucalyptus pulp and tobacco stalk pulp). This study include the morphological characterization of the fibers and the study of effects that the use of fiber has on the fiber cement suspensions and on the mechanical and physical properties of the final product. The flexural strength of fiber cement samples using tobacco stalk pulp after curing in an autoclave at 180 °C for 4 hours is 14.21 MPa which is slightly lower than that of the samples using eucalyptus pulp at 17.10 MPa. However, the results obtained in the tests confirmed the high potential of the tobacco stalk as a source of fiber for the fabrication of a fiber cement capable of meeting the requirements of demanding applications.