Nehal Salahuddin

Photocrosslinked polymers based on pendant extended chalcone as photoreactive moieties

Abstract The photoreactivity of new homo- and co-photosensitive polymers containing pendant chalcone moieties attached through hexamethylene spacer lengths between the photosensitive group and the backbone were studied. The rates of crosslinking of the prepared polymers were investigated under different conditions in solutions such as: backbone structures, copolymerization, different solvents, different concentrations and different temperatures. The structures of the prepared monomer and polymers were confirmed by different spectroscopic methods and elemental microanalysis. The average molecular weights of the polymers were determined by gel permeation chromatography. The thermal stability of the polymers was measured by thermogravimetric analysis under a nitrogen atmosphere.

Modified Chitosan-Clay Nanocomposite as a Drug Delivery System Intercalation and In Vitro Release of Ibuprofen

The present paper focused on the intercalation of ibuprofen into sodium montmorillonite, chitosan, and chitosan montmorillonite nanocomposites as a sustained release drug carrier. The compounds were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The basal spacing of montmorillonite increased from 9.6 A to 19.6 A indicating the intercalation of modified chitosan and ibuprofen between lamellar layers. UV spectroscopy was employed to monitor the in vitro drug release processes in both pH 5.4 and 7.8 solutions. The results revealed that ibuprofen was released from MMT, CS, and Mod-CS/MMT steadily and was pH dependent.

Reduction of polymerization shrinkage in methyl methacrylate-montmorillonite composites

Polymethylmethacrylate-clay composites were synthesized by adding an organophilic montmorillonite up to 1% by weight to one commercial type of polymethylmethacrylate. Acrylic test specimens were processed by the conventional heat curing method following the manufacturers instructions. Evidence for the reduction of warpage and linear dimensional changes in composites was provided using a travelling microscope. The resulting materials have been identified by X-ray diffraction and thermogravimetric analysis.

Trace determination of vardenafil hydrochloride in commercial formulation and human serum by adsorptive anodic stripping voltammetry at a carbon paste electrode

The electrochemical behavior of vardenafil HCl (VRL) at a carbon paste electrode (CPE) was investigated by cyclic voltammetry, and the mechanism of its oxidation was suggested and discussed. A simple Nujol-based CPE in combination with a sensitive square-wave adsorption anodic stripping voltammetry method was described for trace determination of VRL. The described method showed excellent performance for trace determination of VRL in its formulation “Levitra® tablets” without interference from excipients. The results were statistically compared with those obtained with an established HPLC method; nonsignificant differences were found between the described voltammetric and HPLC methods. The described stripping voltammetric method is highly sensitive (limit of detection = 3 × 10−10 mol L−1 and limit of quantitation = 1 × 10−9 mol L−1). It was successfully applied for the determination of VRL in spiked human serum without the necessity for pretreatment and/or time-consuming extraction steps prior to the analysis.

Drug Release Behavior and Antitumor Efficiency of 5-ASA Loaded Chitosan-Layered Silicate Nanocomposites

Abstract5-Amino salicylic acid (5-ASA) loaded chitosan (CS)-montmorillonite nanocomposites were prepared by different methods and using different ratios of modified CS. CS was modified first through chloroacetylation followed by formation of phosphonium salt. The intercalation occurred through ion exchange process between sodium cations in MMT and phosphonium ions in the modified CS. The structure of the resulting composites as determined by Infra red spectroscopy, X-ray diffraction, consisted of the insertions of modified CS between lamellar layers. The modified CS is strongly fixed to layered silicate. The morphology of these materials was examined by transmission electron microscopy. The thermal stability of the nanocomposite was investigated by thermogravimetry analysis. The release of 5-ASA behavior from nanocomposites at different pH (5.4 and 7.8) was assessed. The dispersed layered silicate platelets encase the 5-ASA retarding the release of the drug molecule in the nanocomposite. Furthermore, their use as antitumor agents for treatment of colon cancer is investigated.

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.

Adsorptive stripping voltammetry determination of the hormone therapy Raloxifene HCl in formulation and human serum

Raloxifene HCl (RLX) was found to strongly adsorb onto surface of the mercury electrode in a monolayer surface coverage of 5.724 × 10-10 mol cm-2. Two precise, rapid and extraction-free linear sweep and square wave adsorptive cathodic stripping voltammetry (LS-AdCSV and SW-AdCSV, respectively) methods are described for trace quantitation of RLX in bulk form, commercial formulation and human serum. Limits of quantification (LOQ) of 2.0 × 10-9 and 5.0 × 10-11 mol L-1 RLX in bulk form and 4.0 × 10-9 and 1.0 × 10-10 mol L-1 RLX in spiked human serum were achieved by the described LS-AdCSV and SW-AdCSV methods, respectively. Insignificant interferences from some common excipients, metal ions and co-administrated drugs were obtained. LOQ achieved by the methods are low as well as they offer good possibilities for determination of drug in low-dosage pharmaceutical preparations. However, the SW-AdCSV method described is sensitive enough to assay the drug also in human serum.

pH-Responsive sulphonated mesoporous silica: a comparative drug release study

Control of morphology and surface functionalization of mesoporous silica materials have enhanced the biocompatibility of these materials with high surface areas and total pore volumes. The functionalization of mesoporous silica materials with organic moieties exhibited controlled release and molecular recognition capabilities for drug delivery. Design of functional mesoporous silica with various mechanisms of controlled release and introduction of new characteristics is very interesting for the construction of highly selective drug carrier. Loading of procaine hydrochloride drug (PrHy) into functionalized KIT-6-SO3H and SBA-15-SO3H was investigated by a quartz crystal microbalance (QCM) technique and UV-visible spectroscopy. The release was carefully studied by systematically tuning the pH media at simulating gastric fluid without pepsin (SGF, pH 2) and simulating intestinal fluid without pancreatin (SIF, pH 7.4), as well.

Fabrication of biosensor based on Chitosan-ZnO/Polypyrrole nanocomposite modified carbon paste electrode for electroanalytical application

A sensitive conductive nanocomposite sensor consisting of chitosan, zinc oxide nanoparticles, and polypyrrole was developed. The sensor was prepared by oxidative polymerization of pyrrole using (NH4)2S2O8 as the oxidant followed by mixing a Chitosan-Zinc oxide composite with a different content of Chitosan. The morphology and surface area of the nanocomposites were changed by changing the percentage of chitosan. The newly developed nanocomposites also showed a significant improvement in electrical conductivity as mentioned from the cyclic voltammetry measurements of the K3[Fe(CN)6] sample. A square-wave adsorptive anodic stripping voltammetry method successfully measured Isoxsuprine hydrochloride using different types of nanocomposite modified CPEs and showed a large enhancement of stripping peak current compared to bare CPE. Consequently, the proposed sensors proved to have a promissing feature for applications in biosensors.

Antibacterial and anticancer activity of loaded quinazolinone polypyrrole/chitosan silver chloride nanocomposite

ABSTRACT Polypyrrole/chitosan-silver chloride core shell nanocomposite (AgCl@PPC) was prepared by in situ oxidative polymerization of pyrrole (Py) using ferric chloride in the presence of chitosan (CS) and silver nitrate to develop a carrier and controlled release system for 3-amino-2-phenyl-4(3H)-quinazolinone (I). For sake of comparison, polypyrrole chitosan core shell nanoparticles (PPC) were prepared and loaded by (I). Fourier transform infrared spectroscopy, X-ray diffraction and thermal gravimetric analysis confirm that I was loaded into PPC and AgCl@PPC core shell nanocomposites respectively, through physical interaction. Results revealed that loaded AgCl@PPC and PPC exhibited excellent antibacterial and anticancer efficacy against Ehrlich ascites carcinoma cells. GRAPHICAL ABSTRACT