Polysaccharides are ideal candidates for drug delivery and biomedical applications as they are easily obtained from natural sources. Furthermore, they can be subjected to a wide range of chemical and enzymatic reactions, they have biocompatible and biodegradable properties and have inherently low immunogenicity. Polysaccharides are potentially the materials of choice for the development of “smart” delivery systems, which are capable of releasing, at the appropriate time and site of action, an encapsulated drug. This Review examines various aspects of the crosslinking of polysaccharides, either for a single polysaccharide or mixtures, and also natural–synthetic hybrids. The Review focuses on the strategies for using these biodegradable polymers for controlled drug delivery, and examines in particular polysaccharide–drug conjugates, the encapsulation of drugs in hydrogels and aerogels, and the self‐assembly of polysaccharide drug‐loaded nanoparticles.

Abstract:Sago biomass is an agro-industrial waste produced in large quantities, mainly in the Asia-Pacific region and in particular South-East Asia. This work focuses on using sago biomass to obtain cellulose as the raw material, through chemical processing using acid hydrolysis, alkaline extraction, chlorination and bleaching, finally converting the material to pharmaceutical grade carboxymethyl sago cellulose (CMSC) by carboxymethylation. The cellulose was evaluated using Thermogravimetric Analysis (TGA), Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Field Emission Scanning Electronic Microscopy (FESEM). The extracted cellulose was analyzed for cellulose composition, and subsequently modified to CMSC with a degree of substitution (DS) 0.6 by typical carboxymethylation reactions. X-ray diffraction analysis indicated that the crystallinity of the sago cellulose was reduced after carboxymethylation. FTIR and NMR studies indicate that the hydroxyl groups of the cellulose fibers were etherified through carboxymethylation to produce CMSC. Further characterization of the cellulose and CMSC were performed using FESEM and DSC. The purity of CMSC was analyzed according to the American Society for Testing and Materials (ASTM) International standards. In this case, acid and alkaline treatments coupled with high-pressure defibrillation were found to be effective in depolymerization and defibrillation of the cellulose fibers. The synthesized CMSC also shows no toxicity in the cell line studies and could be exploited as a pharmaceutical excipient.

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Abstract:In the present work, we report for the first time the complex coacervation of carboxymethyl sago pulp (CMSP) with gelatine for sustained drug delivery. Toluene saturated with glutaraldehyde and aqueous aluminum chloride was employed as cross-linkers. Measurements of zeta potential confirm neutralization of two oppositely charged colloids due to complexation, which was further supported by infrared spectroscopy. The coacervates encapsulated a model drug ibuprofen and formed microcapsules with a loading of 29%-56% w/w and an entrapment efficiency of 85%-93% w/w. Fresh coacervates loaded with drug had an average diameter of 10.8 ± 1.93 µm (n = 3 ± s.d.). The coacervates could encapsulate only the micronized form of ibuprofen in the absence of surfactant. Analysis through an optical microscope evidenced the encapsulation of the drug in wet spherical coacervates. Scanning electron microscopy revealed the non-spherical geometry and surface roughness of dried drug-loaded microcapsules. X-ray diffraction, differential scanning calorimetry and thermal analysis confirmed intact and crystalline ibuprofen in the coacervates. Gas chromatography indicated the absence of residual glutaraldehyde in the microcapsules. Dual cross-linked OPEN ACCESSPolymers 2015, 7 1089 microcapsules exhibited a slower release than mono-cross-linked microcapsules and could sustain the drug release over the period of 6 h following Fickian diffusion.

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