Confinement and controlled release of quinine on chitosan-montmorillonite bionanocomposites

Recent advances in chitosan-based materials; The synthesis, modifications and biomedical applications

The attention to polymer-based biomaterials, for instance, chitosan and its derivatives, as well as the techniques for using them in numerous scientific domains, is continuously rising. Chitosan is a decomposable naturally occurring polymeric material that is mostly obtained from seafood waste. Because of its special ecofriendly, biocompatible, non- toxic nature as well as antimicrobial properties, chitosan-based materials have received a lot of interest in the field of biomedical applications. The reactivity of chitosan is mainly because of the amino and hydroxyl groups in its composition, which makes it further fascinating for various uses, including biosensing, textile finishing, antimicrobial wound dressing, tissue engineering, bioimaging, gene, DNA and drug delivery and as a coating material for medical implants. This study is an overview of the different types of chitosan-based materials which now a days have been fabricated by applying different techniques and modifications that include etherification, esterification, crosslinking, graft copolymerization and o-acetylation etc. for hydroxyl groups' processes and acetylation, quaternization, Schiff's base reaction, and grafting for amino groups' reactions. Furthermore, this overview summarizes the literature from recent years related to the important applications of chitosan-based materials (i.e., thin films, nanocomposites or nanoparticles, sponges and hydrogels) in different biomedical applications.

A review on chitosan and chitosan-based bionanocomposites: Promising material for combatting global issues and its applications

Over the last few years, several attempts have been made to replace petrochemical products with renewable and biodegradable components. The most challenging part of this approach is to obtain bio-based materials with properties and functions equivalent to those of synthetic products. Various naturally occurring polymers such as starch, collagen, alginate, cellulose, and chitin represent attractive candidates as they could reduce dependence on synthetic products and consequently positively impact the environment. Chitosan is also a unique bio-based polymer with excellent intrinsic properties. It is known for its anti-bacterial and film-forming properties, has high mechanical strength and good thermal stability. Nanotechnology has also applied chitosan-based materials in its most recent achievements. Therefore, numerous chitosan-based bionanocomposites with improved physical and chemical characteristics have been developed in an eco-friendly and cost-effective approach. This review discusses various sources of chitosan, its properties and methods of modification. Also, this work focuses on diverse preparation techniques of chitosan-based bionanocomposites and their emerging application in various sectors. Additionally, this review sheds light on future research scope with some drawbacks and challenges to motivate the researchers for future outstanding research works.

Recent developments in the use of organic-inorganic nanohybrids for drug delivery

Organic-inorganic nanohybrid (OINH) structures providing a versatile platform for drug delivery with improved characteristics are an area which has gained recent attention. Much effort has been taken to develop these structures to provide a viable treatment options for much alarming diseases such as cancer, bone destruction, neurological disorders, and so on. This review focuses on current work carried out in producing different types of hybrid drug carriers identifying their properties, fabrication techniques, and areas where they have been applied. A brief introduction on understating the requirement for blending organic-inorganic components into a nanohybrid drug carrier is followed with an elaboration given about the different types of OINHs developed currently highlighting their properties and applications. Then, different fabrication techniques are discussed given attention to surface functionalization, one-pot synthesis, wrapping, and electrospinning methods. Finally, it is concluded by briefing the challenges that are remaining to be addressed to obtain multipurpose nanohybrid drug carriers with wider applicability. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Research on 5-fluorouracil as a drug carrier materials with its in vitro release properties on organic modified magadiite

The magadiite (MAG) was modified by cetyltrimethyl ammonium-Bromide (CTAB) and then further modified by Chitosan (CS) which is called organic modified-magadiite as magadiite-cetyltrimethyl ammonium bromide (MAG-CTAB) and magadiite-cetyltrimethyl ammonium bromide-Chitosan (MAG-CTAB-CS), respectively, in this research study. The MAG, MAG-CTAB, and MAG-CTAB-CS were used as 5-Fluorouracil (5-FU) drug carrier materials; the drug carrier's materials were marked as magadiite-5-Fluorouracil (MAG/5-FU), magadiite-cetyltrimethyl ammonium bromide-5-Fluorouracil (MAG-CTAB/5-FU), and magadiite-cetyltrimethyl ammonium bromide-Chitosan (MAG-CTAB-CS/5-FU). X-ray diffraction(XRD, Flourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) results were shown that 5-Fluorouracil was combined with carrier materials through physical apparent adsorption, ion exchange, chemical bond, hydrogen bond, and electrostatic interaction. The drug carriers in vitro release behavior in simulated gastric fluids (SGF，pH = 1.35) and intestinal fluids (SIF，pH = 7.40) were investigated. The drug loading capacity and accumulated release ration were as follows the order: MAG-CTAB-CS/5-FU > MAG-CTAB/5-FU > MAG/5-FU. The drug loading capacity of MAG-CTAB-CS/5-FU was 162.29 mg/g, 48 h later the drug accumulated release ratio was 61.24%, and the release amount was 97.52 mg/g for 24 h. Korsmeyer-Peppas model and First order model were found to be suitable to describe the vitro release behavior of 5-Fluorouracil. This would be an economically viable and efficient method for the preparation of advanced drug delivery system.

Layered Silicates as a Possible Drug Carrier

The potential of layered silicates as drug carrier is overviewed. Due to their large surface area and expandable interlayer space to accommodate drug molecules, layered silicates have a potential as carrier of various molecules. In addition to the electrostatic interactions between negatively charged layered silicates and positively charged drug molecules, the organic modification of the surface of layered silicates has been applied to accommodate a variety of drug molecules not only cationic ones. The in vitro release experiment of the accommodated drug molecules has been reported under the acidic conditions. In order to discuss the future direction of layered silicates as drug carrier, materials' variation of layered silicates and their modification, and the reported stimuli-responsive hybrids based on layered silicates were introduced.

PEG-PE/clay composite carriers for doxorubicin: Effect of composite structure on release, cell interaction and cytotoxicity

A novel drug delivery system for doxorubicin (DOX), based on organic-inorganic composites was developed. DOX was incorporated in micelles (M-DOX) of polyethylene glycol-phosphatidylethanolamine (PEG-PE) which in turn were adsorbed by the clay, montmorillonite (MMT). The nano-structures of the PEG-PE/MMT composites of LOW and HIGH polymer loadings were characterized by XRD, TGA, FTIR, size (DLS) and zeta measurements. These measurements suggest that for the LOW composite a single layer of polymer intercalates in the clay platelets and the polymer only partially covers the external surface, while for the HIGH composite two layers of polymer intercalate and a bilayer may form on the external surface. These nanostructures have a direct effect on formulation stability and on the rate of DOX release. The release rate was reversely correlated with the degree of DOX interaction with the clay and followed the sequence: M-DOX>HIGH formulation>LOW formulation>DOX/MMT. Despite the slower release from the HIGH formulation, its cytotoxicity effect on sensitive cells was as high as the "free" DOX. Surprisingly, the LOW formulation, with the slowest release, demonstrated the highest cytotoxicity in the case of Adriamycin (ADR) resistant cells. Confocal microscopy images and association tests provided an insight into the contribution of formulation-cell interactions vs. the contribution of DOX release rate. Internalization of the formulations was suggested as a mechanism that increases DOX efficiency, particularly in the ADR resistant cell line. The employment of organic-inorganic hybrid materials as drug delivery systems, has not reached its full potential, however, its functionality as an efficient tunable release system was demonstrated.

STATEMENT OF SIGNIFICANCE

DOX PEG-PE/clay formulations were design as an efficient drug delivery system. The main aim was to develop PEG-PE/clay formulations of different structures based on various PEG-PE/clay ratios in order to achieve tunable release rates, to control the external surface characteristics and formulation stability. The formulations showed significantly higher toxicity in comparison to "free" DOX, explained by formulation internalization. For each cell line tested, sensitive and ADR resistant, a different formulation structure was found most efficient. The potential of PEG-PE/clay-DOX formulations to improve DOX administration efficacy was demonstrated and should be further explored and implemented for other cancer drugs and cells.

Developing Polycation-Clay Sorbents for Efficient Filtration of Diclofenac: Effect of Dissolved Organic Matter and Comparison to Activated Carbon

The presence of nanoconcentrations of persistent pharmaceuticals in treated wastewater effluent and in surface water has been frequently reported. A novel organic-inorganic hybrid sorbent based on adsorbing quarternized poly vinylpyridinium-co-styrene (QPVPcS) to montmorillonite (MMT) was designed for the removal of the anionic micropollutants. QPVPcS-clay composites were characterized by X-ray diffraction, FTIR, thermal gravimetric analysis, Zeta potential and element analysis. Based on these measurements polymer-clay micro- and nanostructures, as a function of polymer loading, were suggested. The affinity of the anionic pharmaceutical, diclofenac (DCF), to the composite was high and did not decrease dramatically with an increase of ionic strength, indicating that the interactions are not only electrostatic. The presence of humic acid (HA) did not hinder DCF removal by the composite; whereas, its filtration by granulated activated carbon (GAC) was compromised in the presence of HA. The kinetics and adsorption at equilibrium of DCF to the composite and to GAC were measured and modeled by the time dependent Langmuir equation. The adsorption of DCF to the composite was significantly faster than to GAC. Accordingly, the filtration of micro- and nanoconcentrations of DCF by composite columns, in the presence of HA, was more efficient than by GAC columns.

Biodegradable gelatin-ciprofloxacin-montmorillonite composite hydrogels for controlled drug release and wound dressing application

This work reports intercalation of a sparingly soluble antibiotic (ciprofloxacin) into layered nanostructure silicate, montmorillonite (MMT) and its reaction with bone derived polypeptide, gelatin that yields three-dimensional composite hydrogel. Drug intercalation results in changes in MMT layered space and drug loaded MMT and gelatin creates 3D morphology with biodegradable composite hydrogels. These changes can be correlated with electrostatic interactions between the drug, MMT and the gelatin polypeptides as confirmed by X-ray diffraction patterns, thermal, spectroscopic analyses, computational modeling and 3D morphology revealed by SEM and TEM analysis. No significant changes in structural and functional properties of drug was found after intercalation in MMT layers and composite hydrogels. In vitro drug release profiles showed controlled release up to 150h. The drug loaded composite hydrogels were tested on lung cancer cells (A549) by MTT assay. The results of in vitro cell migration and proliferation assay were promising as composite hydrogels induced wound healing progression. In vitro biodegradation was studied using proteolytic enzymes (lysozyme and protease K) at physiological conditions. This new approach of drug intercalation into the layered nanostructure silicate by ion-exchange may have significant applications in cost-effective wound dressing biomaterial with antimicrobial property.

Structural studies of adsorbed protein (betalactoglobulin) on natural clay (montmorillonite)

Adsorption of betalactoglobulin on montmorillonite leads to structural changes of the protein accompanied by a partial exfoliation of clay.

The Layered Silicate, Montmorillonite (MMT) as a Drug Delivery Carrier

Controlled drug delivery system is a protocol to develop nanostructures and materials that can efficiently encapsulate drugs at high concentration, cross the cell membrane, and release the drug at the target site in a controlled manner for a prescribed period of time. This system can reduces the patient expenses, and risks of toxicity, while it can increase the drug efficacy, specificity, tolerability and therapeutic index of corresponding drugs. Therefore, construction of stimuli-responsive controlled-release systems is of crucial importance for the development of both fundamental science and clinical medicine. Both natural and synthetic materials have been tested and proposed as components of controlled drug delivery. Clay minerals, synthetic or natural, are an important, widely abundant, and low-cost class of materials with unique swelling, intercalation, adsorption, and ion-exchange properties. The safety proof data of clay minerals clearly suggest them to be non-toxic for transdermal application and oral administration. To accomplish controlled-release systems based on layered clay minerals, one of the best ways is to intercalate organic molecules into the interlayer gallery of clay minerals. Intercalation of organic molecules within the gallery of layered silicates offers a novel route to prepare organic and inorganic hybrids that contain properties of both the inorganic host and organic guest in a single material. In this article we will highlight the applications of clay in pharmaceutics as controlled drug delivery carrier.