Synthesis of amidic alginate derivatives and their application in microencapsulation of λ-cyhalothrin.

1-Octyl amine was covalently coupled to sodium alginate(NaAlg) in an aqueous-phase reaction via acidamide functions using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC-HCl) as a coupling reagent to provide octyl-grafted amphiphilic alginate-amide derivative(OAAD) for subsequent use in λ-cyhalothrin (LCH) microcapsule application. The structure of OAAD was confirmed by FT-IR and (1)H NMR spectroscopies. The new alginate-amide derivative was used for fabricating microcapsule that can effectively encapsulate LCH by emulsification-gelation technique. The microcapsules were characterized by optical microscopy (OM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and laser particle size analysis. The encapsulation efficiency and drug release behavior of LCH from the microcapsules were investigated. Results showed that the microcapsules were in spherical form with diameter mostly in the range of 0.5-10 µm and possessed a structure with LCH as core and OAAD as shell. The encapsulation efficiency and the release performance of the microcapsules were influenced by DS of OAAD and amount of CaCl(2). The mechanism of LCH release was found to vary from anomalous to Fickian to quasi-Fickian transport with the DS of OAAD varied from 10.8 to 30.3 and the CaCl(2)/emulsion ratios varied from 0.09 to 0.03%.

Preparation and application of cyclodextrin immobilized polysaccharides.

Cyclodextrins (CDs) are cyclic oligosaccharides which have recently been recognized as useful matrices. Due to its hydrophobic cavity, CD can interact with appropriately sized molecules to result in the formation of inclusion complexes. CD immobilized polysaccharide is a kind of novel functional macromolecule that possesses the cumulative effects of inclusion, size specificity, controlled release ability and transport properties of CD as well as the biocompatibility, non-toxicity, and biodegradability of polysaccharide. Their nanoscale association could also lead to the formation of original particles and films which pave the way to new applications such as drug delivery, tissue engineering and separation processes. In this review, different methods of immobilizing CD onto polysaccharide are discussed. In addition, the properties of CD immobilized polysaccharide derivatives and their potential applications are reviewed.

Amphipathicity and self-assembly behavior of amphiphilic alginate esters.

Amphiphilic alginate esters (Alg-C(n)) with different degree of substitution (DS) and hydrophobic alkyl length were synthesized by the reaction between partially protonated sodium alginate and aliphatic alcohols (octanol, dodecanol or hexadecanol) and characterized by conventional methods. The critical micelles concentration (CMC) of Alg-C(n) was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe, conductance and surface tension (SFT). Formation and characteristics of the self-assembly micelles of Alg-C(n) were studied by transmission electron microscopy (TEM) and Zetasizer Nano Series method. The results indicate that CMC value and the self-assembled micelle size decreased with the increasing of the hydrophobic alkyl chain length, as the DS of Alg-C(n) is similar.