Ahmed Salama

Carboxymethyl cellulose-g-poly(2-(dimethylamino) ethyl methacrylate) hydrogel as adsorbent for dye removal

A novel adsorbent was prepared via crosslinking graft copolymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA) onto carboxymethyl cellulose (CMC) backbone. Ethylene glycol dimethacrylate and potassium persulphate were used as crosslinker and initiator, respectively. CMC-g-PDMAEMA hydrogel was used to remove methyl orange (MO) from aqueous solutions. The adsorption kinetics and isotherms were found to follow Pseudo-second-order kinetic model and Langmuir model, respectively. The high maximum adsorption capacity (1825 mg/g) implied that CMC-g-PDMAEMA can be used as promising adsorbent for the synthetic dyes removal from wastewater.

Preparation of polyelectrolyte/calcium phosphate hybrids for drug delivery application.

Biocompatible and biodegradable polyelectrolyte complex consisting of carboxylmethyl cellulose (CMC) and chitosan (CHI) were studied as a template for calcium phosphate biomimetic mineralization. CMC/CHI/calcium phosphate hybrids were prepared using different concentrations of simulated body fluid (2, 5 and 10 × SBF) for producing hybrids with different organic/inorganic ratio. These hybrids were characterized using X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The equilibrium swelling extents of the hybrids were found to be dependent on the inorganic % in the hybrids. The release profile of bovine serum albumin as a model drug in simulated intestine solution (pH 7.4) during 24h has established the efficiency of the hybrids as a sustained delivery system. The hybrids developed in this contribution exhibit a great potential in bone tissue engineering and drug delivery applications.

New sustainable hybrid material as adsorbent for dye removal from aqueous solutions

Cellulose grafted with soy protein isolate (SPI), sustainable and cost effective material, was investigated as a bioactive material for calcium phosphate mineralization. The formation of hydroxyapatite rod-like nanocrystals with ∼50nmdiameter was confirmed by different characterization tools. Cellulose grafted SPI/hydroxyapatite hybrid was evaluated as recyclable adsorbent for methylene blue (MB) from aqueous solutions using batch adsorption technique. The new sustainable material exhibited adsorption capacity up to 454mg/g. Adsorption data were examined using different kinetics and isotherms to investigate the adsorption mechanism. After four adsorption-desorption cycles, the efficiency of MB removal is ∼95%. These results present new sustainable, cost effective and reusable hybrid material as a promising adsorbent for organic dyes removal from waste water.

Ionic liquid-assisted formation of cellulose/calcium phosphate hybrid materials

Summary Cellulose/calcium phosphate hybrid materials were synthesized via an ionic liquid-assisted route. Scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis/differential thermal analysis show that, depending on the reaction conditions, cellulose/hydroxyapatite, cellulose/chlorapatite, or cellulose/monetite composites form. Preliminary studies with MC3T3-E1 pre-osteoblasts show that the cells proliferate on the hybrid materials suggesting that the ionic liquid-based process yields materials that are potentially useful as scaffolds for regenerative therapies.

Polysaccharides/silica hybrid materials: New perspectives for sustainable raw materials

ABSTRACT Polysaccharides/silica hybrids prepared through sol-gel reaction have been studied as a model for new generation of hybrid materials for a virtually unlimited number of applications. Numerous studies have therefore attempted to increase the homogeneity between the organic and inorganic moieties using a wide variety of silica precursors and crosslinking reagents. The current review summarizes and discusses the attempts for using polysaccharides for producing hybrid materials with collective properties from the two counterparts. It discusses several issues and strategies to tune the homogeneity of polysaccharide/silica hybrids and the potential applicability of these hybrid materials in biomedical and industrial fields. GRAPHICAL ABSTRACT

Ionotropically cross-linked pH-sensitive IPN hydrogel matrices as potential carriers for intestine-specific oral delivery of protein drugs.

Background: The oral delivery of proteins and peptide drugs is considered a major challenge. These types of therapeutics are readily degraded, if taken orally, due to the harsh high acidity of stomach and enzymatic attack in the upper small intestinal tract. Methods: Water-soluble copolymers of sodium acrylate (AAs) grafted onto carboxymethyl cellulose (CMC) were prepared and characterized using Fourier transform spectroscopy, differential scanning calorimetry, and X-ray diffraction. The obtained graft copolymers were then used in a combination with sodium alginate to develop a new series of pH-sensitive interpenetrating polymeric network (IPN) hydrogels through ionotropic gelation with divalent ions (Ca2+). Morphology of the developed hydrogels was investigated using SEM. Swelling characteristics, at distinct compositions, were also studied at 37°C in two consecutive buffer solutions of pH 2.1 and 7.4 (similar to that of gastric and intestinal fluids, respectively). The release profiles of bovine serum albumin, as a model protein, from test IPN hydrogel films were studied in simulated gastric and intestinal fluids. In addition, the drug release process was confirmed by means of SEM. Results: Swelling studies of the developed IPN hydrogels at different pH values confirmed their pH-sensitive nature. The equilibrium swelling extents of the hydrogels were found to be dependent on the grafting yield of CMC/AAs graft copolymer. The IPN hydrogels attained equilibrium swelling percentages in the range 445–740%. In addition, the amount of bovine serum albumin released within 2 hours in pH 2.1 was relatively low (less than 18.1%). This amount increased up to 68% after 8 hours in pH 7.4. Conclusions: From the obtained preliminary data, it seems that the IPN hydrogels developed in this contribution can be tailored to act as good potential carriers for oral delivery of protein drugs. These hydrogels showed a promising protection of protein drugs from the harsh acidity of stomach and, at the same time, they conferred sustained drug release in the intestinal fluid.

Grafting Study and Antifungal Activity of a Carboxymethyl Cellulose Derivative

Graft copolymerization of appropriate monomers onto cellulose and its derivatives can enhance their characteristics and consequently expand their potential applications. Carboxymethyl cellulose (CMC) was prepared and characterized by FTIR spectroscopy and XRD. Graft copolymerization of acrylic acid sodium salt (AAs) onto CMC using ammonium persulfate (APS) as a free radical initiator was carried out under nitrogen atmosphere in aqueous solution. Occurrence of grafting was confirmed by comparison of FTIR spectra of CMC and the graft copolymers as well as the XRD patterns and thermal analysis. The effects of concentration of AA, temperature, concentration of APS and reaction time on the grafting yield were investigated by determining the grafting percentage and grafting efficiency. With other conditions kept constant, the obtained optimum grafting conditions were: CMC = 0.2 g, [AAs] = 2 mM, [APS] = 7.5 mM, temperature = 70°C and reaction time = 2 h. A preliminary study was then carried out to evaluate the antifungal activity of the prepared graft copolymer. This preliminary investigation of the prepared graft copolymers showed that they may be tailored and exploited to expand the utilization of these systems in medical applications.

Carboxymethyl cellulose/silica hybrids as templates for calcium phosphate biomimetic mineralization.

Multiphase hybrid materials were synthesized using carboxymethyl cellulose (CMC) as bioactive polymer, silica gel as matrix assisted networks and calcium phosphate as inorganic mineral phase. These hybrids were investigated with infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. Biomimetic crystal growth nucleated from the CMC/silica hybrids was suggested as amorphous calcium phosphate with an evidence that hydroxyapatite, the mineralized component of bone, may be formed at high CMC content. This study provides an efficient approach toward bone-like hybrids with potential bone healing applications.

Carboxymethyl cellulose based hybrid material for sustained release of protein drugs.

Hybrid materials contain polysaccharide based network and biomimetic calcium phosphate are potentially appropriate for bone repair and drug release. Novel hydrogel composed of carboxymethyl cellulose backbone grafted with crosslinked poly(dimethylaminoethyl methacrylate) CMC-g-PDMAEMA was subjected to biomimetic calcium phosphate mineralization through simulated body fluid. Infrared spectroscopy (IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) confirmed calcium phosphate mineralization while X-ray diffraction and transmission electron microscopy (TEM) results suggested that the deposited phase contains mineralized component of bone, hydroxyapatite. CMC-g-PDMAEMA hydrogels before and after calcium phosphate mineralization were investigated as a drug carrier and the results showed significant efficiency of the mineralized hydrogel to deliver bovine serum albumin (BSA). These results indicated that CMC-g-PDMAEMA/calcium phosphate could serve as a new class of multifunctional hybrid materials for various biomedical applications.

Regenerated cellulose/wool blend enhanced biomimetic hydroxyapatite mineralization.

The current article investigates the effect of bioactive cellulose/wool blend on calcium phosphate biomimetic mineralization. Regenerated cellulose/wool blend was prepared by dissolution-regeneration of neat cellulose and natural wool in 1-butyl-3-methyl imidazolium chloride [Bmim][Cl], as a solvent for the two polymers. Crystalline hydroxyapatite nanofibers with a uniform size, shape and dimension were formed after immersing the bioactive blend in simulated body fluid. The cytotoxicity of cellulose/wool/hydroxyapatite was studied using animal fibroblast baby hamster kidney cells (BHK-21) and the result displayed good cytocompatability. This research work presents a green processing method for the development of novel cellulose/wool/hydroxyapatite hybrid materials for tissue engineering applications.