The Influence of Pineapple Leaf Fiber Orientation and Volume Fraction on Methyl Methacrylate-Based Polymer Matrix for Prosthetic Socket Application.

This work reports on the use of low-cost pineapple leaf fiber (PALF) as an alternative reinforcing material to the established, commonly used material for prosthetic socket fabrication which is carbon-fiber-reinforced composite (CFRC) due to the high strength and stiffness of carbon fiber. However, the low range of loads exerted on a typical prosthetic socket (PS) in practice suggests that the use of CFRC may not be appropriate because of the high material stiffness which can be detrimental to socket-limb load transfer. Additionally, the high cost of carbon fiber avails opportunities to look for an alternative material as a reinforcement for composite PS development. PALF/Methyl Methacrylate-based (MMA) composites with 0°, 45° and 90° fiber orientations were made with 5-50 v/v fiber volume fractions. The PALF/MMA composites were subjected to a three-point flexural test to determine the effect of fiber volume fraction and fiber orientation on the flexural properties of the composite. The results showed that 40% v/v PALF/MMA composite with 0° fiber orientation recorded the highest flexural strength (50 MPa) and stiffness (1692 MPa). Considering the average load range exerted on PS, the flexural performance of the novel composite characterized in this work could be suitable for socket-limb load transfer for PS fabrication.

Chitosan-Coated Halloysite Nanotubes As Vehicle for Controlled Drug Delivery to MCF-7 Cancer Cells In Vitro.

The aim of the work is to improve the release properties of curcumin onto human breast cancer cell lines using coated halloysite nanotubes (HNTs) with chitosan as a polycation. A loading efficiency of 70.2% (w/w) was attained for loading 4.9 mg of the drug into 0.204 g bed volume of HNTs using the vacuum suction method. Results acquired from Brunauer-Emmett-Teller (BET), Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron spectroscopy (SEM), zeta potential, and thermogravimetric analysis (TGA) indicated the presence of the drug and the biopolymer in and around the nanotubes. The release properties of drug-loaded HNTs (DLHNTs) and chitosan-coated drug-loaded HNTs (DLHNTs-CH) were evaluated. The release percentages of DLHNTs and DLHNTs-CH after 6 h were 50.7 and 37%, respectively. Based on the correlation coefficients obtained by fitting the release nature of curcumin from the two samples, the Korsmeyer-Peppas model was found to be the best-fitted model. In vitro cell viability studies were carried out on the human breast cancer cell line MCF-7, using the MTT and trypan blue exclusion assays. Prior to the Trypan blue assay, the IC50 of curcumin was determined to be ~30 µM. After 24 h of incubation, the recorded cell viability values were 94, 68, 57, and 51% for HNTs, DLHNTs-CH, DLHNTs, and curcumin, respectively. In comparison to the release studies, it could be deducted that sustained lethal doses of curcumin were released from the DLHNTs-CH within the same time. It is concluded from this work that the "burst release" of naked drugs could be slowly administered using chitosan-coated HNTs as potential drug carriers.

Electrochemical Response of Saccharomyces cerevisiae Corresponds to Cell Viability upon Exposure to Dioclea reflexa Seed Extracts and Antifungal Drugs.

Dioclea reflexa bioactive compounds have been shown to contain antioxidant properties. The extracts from the same plant are used in traditional medical practices to treat various diseases with impressive outcomes. In this study, ionic mobility in Saccharomyces cerevisiae cells in the presence of D. reflexa seed extracts was monitored using electrochemical detection methods to link cell death to ionic imbalance. Cells treated with ethanol, methanol, and water extracts were studied using cyclic voltammetry and cell counting to correlate electrochemical behavior and cell viability, respectively. The results were compared with cells treated with pore-forming Amphotericin b (Amp b), as well as Fluconazole (Flu) and the antimicrobial drug Rifampicin (Rif). The D. reflexa seed water extract (SWE) revealed higher anodic peak current with 58% cell death. Seed methanol extract (SME) and seed ethanol extract (SEE) recorded 31% and 22% cell death, respectively. Among the three control drugs, Flu revealed the highest cell death of about 64%, whereas Amp b and Rif exhibited cell deaths of 35% and 16%, respectively, after 8 h of cell growth. It was observed that similar to SWE, there was an increase in the anodic peak current in the presence of different concentrations of Amp b, which also correlated with enhanced cell death. It was concluded from this observation that Amp b and SWE might follow similar mechanisms to inhibit cell growth. Thus, the individual bioactive compounds from the water extracts of D. reflexa seeds could further be purified and tested to validate their potential therapeutic application. The strategy to link electrochemical behavior to biochemical responses could be a simple, fast, and robust screening technique for new drug targets and to understand the mechanism of action of such drugs against disease models.

Chitosan Composites Synthesized Using Acetic Acid and Tetraethylorthosilicate Respond Differently to Methylene Blue Adsorption.

The sol-gel and cross-linking processes have been used by researchers to synthesize silica-based nanostructures and optimize their size and morphology by changing either the material or the synthesis conditions. However, the influence of the silica nanostructures on the overall physicochemical and mechanistic properties of organic biopolymers such as chitosan has received limited attention. The present study used a one-step synthetic method to obtain chitosan composites to monitor the uptake and release of a basic cationic dye (methylene blue) at two different pH values. Firstly, the composites were synthesized and characterized by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) to ascertain their chemical identity. Adsorption studies were conducted suing methylene blue and these studies revealed that Acetic Acid-Chitosan (AA-CHI), Tetraethylorthosilicate-Chitosan (TEOS-CHI), Acetic Acid-Tetraethylorthosilicate-Chitosan (AA-TEOS-CHI), and Acetic Acid-Chitosan-Tetraethylorthosilicate (AA-CHI-TEOS) had comparatively lower percentage adsorbances in acidic media after 40 h, with AA-CHI adsorbing most of the methylene blue dye. In contrast, these materials recorded higher percentage adsorbances of methylene blue in the basic media. The release profiles of these composites were fitted with an exponential model. The R-squared values obtained indicated that the AA-CHI at pH ~ 2.6 and AA-TEOS-CHI at pH ~ 7.2 of methylene blue had steady and consistent release profiles. The release mechanisms were analyzed using Korsmeyer-Peppas and Hixson-Crowell models. It was deduced that the release profiles of the majority of the synthesized chitosan beads were influenced by the conformational or surface area changes of the methylene blue. This was justified by the higher correlation coefficient or Pearson's R values (R ≥ 0.5) computed from the Hixson-Crowell model. The results from this study showed that two of the novel materials comprising acetic acid-chitosan and a combination of equimolar ratios of acetic acid-TEOS-chitosan could be useful pH-sensitive probes for various biomedical applications, whereas the other materials involving the two-step synthesis could be found useful in environmental remediation of toxic materials.