In vitro evaluation of paclitaxel loaded amorphous chitin nanoparticles for colon cancer drug delivery

Chitin and its derivatives have been widely used in drug delivery applications due to its biocompatible, biodegradable and non-toxic nature. In this study, we have developed amorphous chitin nanoparticles (150±50 nm) and evaluated its potential as a drug delivery system. Paclitaxel (PTX), a major chemotherapeutic agent was loaded into amorphous chitin nanoparticles (AC NPs) through ionic cross-linking reaction using TPP. The prepared PTX loaded AC NPs had an average diameter of 200±50 nm. Physico-chemical characterization of the prepared nanoparticles was carried out. These nanoparticles were proven to be hemocompatible and in vitro drug release studies showed a sustained release of PTX. Cellular internalization of the NPs was confirmed by fluorescent microscopy as well as by flow cytometry. Anticancer activity studies proved the toxicity of PTX-AC NPs toward colon cancer cells. These preliminary results indicate the potential of PTX-AC NPs in colon cancer drug delivery.

Synthesis of phosphorylated chitosan by novel method and its characterization

Chitosan a natural based polymer is non-toxic, biocompatible and biodegradable. Chemical modification of chitosan to generate new bifunctional materials and finally would bring new properties depending on the nature of the group introduced. In our present study, we prepared phosphorylated chitosan (P-chitosan) by using H(3)PO(4)/P(2)O(5)/Et(3)PO(4)/hexanol method. From our present method, we got high yield and high degree of substitution (DS). The prepared P-chitosan (DS-1.18) was characterized by FT IR, (13)C NMR, (31)P NMR, elemental, XRD, TGA, DTA and SEM studies. After the phosphorylation, the solubility of the polymer was improved. The P-chitosan showed less thermal stability and crystallinity than the chitosan. It was due to the phosphorylation.

Design of fluorogenic substrates for continuous assay of sialyltransferase by resonance energy transfer

Glycosyltransferases are important synthetic enzymes for the construction of naturally occurring glycoconjugates as well as for the design of neoglycoconjugates. The assay methods currently available for these enzymes require tedious and time-consuming procedures for separation of products and do not permit continual assay of enzyme activities. As a set of convenient fluorogenic substrates for continuous monitoring of sialyltransferase activities, we designed and synthesized a novel CMP-Neu5Ac derivative with a naphthylmethyl group at the C-9 position and N-acetyllactosamine derivative containing a dansyl group at the terminal position of aglycon. In such substrates, the emission peak of the naphthylmethyl group (lambdaem = 340 nm) of the glycosyl donor is successfully overlapped with the excitation peak due to the dansyl group (lambdaex = 335 nm) of the glycosyl acceptor. A coupling reaction of these two substrates catalyzed by rat liver 2,6-sialyltransferase caused an increase of dansyl fluorescence (lambdaem = 525 nm) and a decrease of naphthylmethyl fluorescence on the basis of resonance energy transfer between two fluorescence probes. The substrates presented here permit continuous fluorescent monitoring of enzymatic sugar combining reactions. Actually, using this time course of enzymatic reactions, kinetic constants of rat liver 2,6-sialyltransferase against glycosyl donor substrates were estimated to be Km = 4.85 microM and Vmax. = 0.119 micromol/min, respectively. This strategy allows precise and efficient analyses of enzyme kinetics not possible with the conventional assay methods for the glycosyltransferases that usually require separation of products from the reaction mixture.

Fluorescence-labeled synthetic glycopolymers: a new type of sugar ligands of lectins

Radical copolymerization of a polymerizable dansyl derivative, N-2-propenyl-(5-dimethylamino)-1-naphthalene sulfonamide, with sugar monomers and acrylamide proceeded smoothly in aqueous solution in the presence of ammonium persulfate and N,N,N',N'-tetramethylethylenediamine and afforded a novel type of water-soluble glycopolymers having fluorescent side-chains. Fluorescence emission spectra of these polymeric sugar-ligands by excitation at 340 nm revealed maxima at 448 and 528 nm. When the glycopolymer carrying galactose residues was saturated with Ricinus communis agglutinin (RCA60), the fluorescence emission maxima at 448 and 528 nm were not shifted significantly, although the fluorescence intensities were decreased by 20 and 14%, respectively. Polymeric sugar-cluster effects drastically enhanced the association constants of galactose residues with RCA60 in the order of 10(8) M-1. The significance for efficient binding of galactose density on the glycopolymer was also demonstrated by using glycopolymers with different degrees of galactose branching.