Superabsorbent polymers (SAPs) are organic materials with lightly crosslinked three-dimensional structure possessing high to very high swelling capacity in aqueous media. These are in fact the most commercially successful members of the hydrogel family. The SAP production for personal care products (baby diapers and feminine incontinence products) accounts for about 80% of the overall hydrogel production. Research during the past 30 years, although not affected the commercial status of SAPs, has led to more and more understanding of superabsorbent structures, their properties, and potential uses. Beyond the hygienic use, the SAPs have found very wide applications from the agricultural formulations to pharmaceutical dosage forms. Since hygiene applications of SAPs are very well established and well reviewed, this article reviews and highlights the SAP applications in other sectors, such as in agriculture, pharmaceutics, separation technology, fibers/textiles, water-swelling rubbers, soft actuators/valves, electrical and construction.

Advances in non-hygienic applications of superabsorbent hydrogel materials

Arylglyoxals in synthesis of heterocyclic compounds.

In recent years, the interest in studying modification of pectin has increased. A number of hydroxyl and carboxyl groups distributed along the backbone as well as a certain amount of neutral sugars presented as side chains make pectin capable of preparing a broad spectrum of derivatives. By forming pectin derivatives, their properties may be modified and some other new functional properties may be created. This article attempts to review the information about various methods used for pectin modification, including substitution (alkylation, amidation, quaternization, thiolation, sulfation, oxidation, etc.), chain elongation (cross-linking and grafting) and depolymerization (chemical, physical, and enzymatic degradation). Characteristics and applications of some pectin derivatives are also presented. In addition, the safety and regulatory status of pectin and its derivatives were reviewed.

Pectin modifications: a review.

Chitosans and pectins are natural polysaccharides which show great potential in drug delivery systems Chitosans are a family of strongly polycationic derivatives of poly-N-acetyl-D-glucosamine This positive charge is very important in chitosan drug delivery systems as it plays a very important role in mucoadhesion (adhesion to the mucosal surface) Other chitosan based drug delivery systems involve complexation with ligands to form chitosan nanoparticles with can be used to encapsulate active compounds Pectins are made of several structural elements the most important of which are the homogalacturonan (HG) and type I rhamnogalacturonan (RG-I) regions often described in simplified terms as the "smooth" and "hairy" regions respectively Pectin HG regions consist of poly-glacturonic acid residues which can be partially methyl esterified Pectins with a degree of methyl esterification (DM) > 50% are known as high methoxyl (HM) pectins and consequently low methoxyl (LM) pectins have a DM less than 50% Low methoxyl pectins are of particular interest in drug delivery as they can form gels with calcium ion (Ca2+) which has potential applications especially in nasal formulations In this chapter we will discuss the physicochemical properties of both chitosans and pectins and how these translate to current and potential drug delivery systems

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Polysaccharide drug delivery systems based on pectin and chitosan.

The over increasing demand of eco-friendly materials to counter various problems, such as environmental issues, economics, sustainability, biodegradability, and biocompatibility, open up new fields of research highly focusing on nature-based products. Edible polymer based materials mainly consisting of polysaccharides, proteins, and lipids could be a prospective contender to handle such problems. Hydrogels based on edible polymer offer many valuable properties compared to their synthetic counterparts. Edible polymers can contribute to the reduction of environmental contamination, advance recyclability, provide sustainability, and thereby increase its applicability along with providing environmentally benign products. This review is highly emphasizing on toward the development of hydrogels from edible polymer, their classification, properties, chemical modification, and their potential applications. The application of edible polymer hydrogels covers many areas including the food industry, agricultural appl...

Recent Advances in Edible Polymer Based Hydrogels as a Sustainable Alternative to Conventional Polymers.

The purpose of this study was to produce intelligent pectin-based superabsorbent polymers (SAP) to be used as pH- and thermosensitive carriers for the controlled delivery of non-steroidal anti-inflammatory drugs (NSAIDs). The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FT-IR) and scanning electron microscopy (SEM). The effects of pH, ionic strength, temperature, porosity, particle size and levels of loaded drug on drug release profile in various surrounding media were investigated. Each sample was well characterized through swelling studies. The molecular weight between crosslinks (M C ), crosslinking density (V e ) polymer-solvent interaction parameter (Χ, and the shear modulus of the superabsorbents (G) were calculated. The results revealed that the release profiles of IBU from the superabsorbent polymer were low (lower than 14%) in simulated gastric fluid (SGF, pH 1.2) over 3 h, but nearly all of the initial drug content (more than 79%) was released in simulated intestinal fluid (SIF, pH 7.4) within 6 h after changing media. Overall the results demonstrated that biodegradable superabsorbents could successfully deliver a drug to the intestine without losing the drug in the stomach, and could be potential candidates for an orally administrated drug delivery system.

Synthesis and Evaluation of pH and Thermosensitive Pectin-Based Superabsorbent Hydrogel for Oral Drug Delivery Systems

A simple, efficient, and environmentally benign route was developed for the preparation of 14-aryl or alkyl-14H-dibenzo[a,j]xanthene, 1,8-dioxo-octahydroxanthene and 12-aryl—8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones from condensation of various aldehydes with (i) β-naphthol, (ii) cyclic 1,3-dicarbonyl compounds and (iii) β-naphthol and cyclic 1,3-dicarbonyl compounds, using novel polymeric catalyst [poly(AMPS-co-AA)] under solvent-free conditions. Use of easily available catalyst, shorter reaction times, better yields, simplicity of the reaction, heterogeneous system, and easy work-up are the advantages of the present method.

A novel polymeric catalyst for the one-pot synthesis of xanthene derivatives under solvent-free conditions

The purpose of this study was to produce an intelligent superabsorbent polymer (SAP) to be used as a pH sensitive matrix for the controlled delivery of drugs. Novel types of highly swelling SAPs were prepared by grafting crosslinked acrylic acid-co-acrylamide (AA-co-AAm) chains onto pectin by free-radical polymerization. The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FT-IR) and scanning electron microscopy (SEM). The controlled release behavior of ibuprofen (IBU) from the superabsorbent polymer was investigated. SAP structural-property relationships that affect its controlled release behavior were determined. Analysis of the results indicated that it is possible to optimize ibuprofen (IBU) controlled release by adjusting the SAP composition and the crosslinking degree of the copolymer. The results revealed that the release profiles of IBU from the superabsorbent polymer were slow (lower than 2%) in simulated gastric fluid (SGF, pH 1.2) over 3 h, but nearly all of the initial drug content (more than 84%) was released in simulated intestinal fluid (SIF, pH 7.4) within 85 h after changing media. Overall the results demonstrated that biodegradable superabsorbents could successfully deliver a drug to the intestine without losing the drug in the stomach, and could be potential candidates as an orally administrated drug delivery system.

Smart Pectin-based Superabsorbent Hydrogel as a Matrix for Ibuprofen as an Oral Non-steroidal Anti-inflammatory Drug Delivery

The synthesis of pure α-Fe2O3 nanoparticles (30 nm) using a superabsorbent nanopolymer (SANP) by the thermal decomposition is reported. Synthesized α-Fe2O3 nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electronic microscopy (TEM) and thermogravimetric analysis (TG) techniques. The applicability of this nanostructure material was assessed by its catalytic effect on the Friedel-Crafts acylation.

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Superabsorbent polymer as nanoreactors for preparation of hematite nanoparticles and application of the prepared nanocatalyst for the Friedel-Crafts acylation

In this study, a low temperature precipitation method was applied to prepare BiOX (X = Cl, Br and I) nanostructures using HCl, HBr and HI as halogen sources. The as-prepared samples were characterized by various techniques such as X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy, Fourier-transform infrared spectroscopy, diffuse reflectance spectroscopy and nitrogen adsorption–desorption analysis. The photoactivity of BiOX samples to degrade rhodamine B (RhB) molecules in aqueous solution was investigated under white LED irradiation. The results indicated that BiOCl exhibits a higher photodegradation performance in comparison with BiOBr and BiOI. Ninety six percent of the RhB molecules was degraded over BiOCl after 25 min light irradiation, whereas under the same conditions, the degradation efficiencies of BiOBr and BiOI samples are 62 and 24%, respectively. The enhanced photodegradation activity of BiOCl is ascribed to the higher specific surface area which increases the physical adsorption of RhB molecules on the photocatalyst surface. Moreover, the photodegradation mechanism and the main radical species in the degradation reactions over BiOCl were investigated.

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Shahram Barzegar

Papers

Synthesis and Evaluation of pH and Thermosensitive Pectin-Based Superabsorbent Hydrogel for Oral Drug Delivery Systems

A novel polymeric catalyst for the one-pot synthesis of xanthene derivatives under solvent-free conditions

Smart Pectin-based Superabsorbent Hydrogel as a Matrix for Ibuprofen as an Oral Non-steroidal Anti-inflammatory Drug Delivery

Superabsorbent polymer as nanoreactors for preparation of hematite nanoparticles and application of the prepared nanocatalyst for the Friedel-Crafts acylation

Investigation of photodegradation of rhodamine B over a BiOX (X = Cl, Br and I) photocatalyst under white LED irradiation