Chitosan-encapsulated Keggin Anion [Ti2W10PO40]7−. Synthesis, Characterization and Cellular Uptake Studies

Abstract

The Keggin type polyoxotungstate [Ti 2 W 10 PO 40 ] 7) forms stable associates with the biopolymer chitosan in the nanometer size range. The cluster compound crystallizes from aqueous solution as K 4 H 3 [Ti 2 W 10 PO 40 ] AE 15H 2 O having a tetragonal structure. Both, the cluster compound and the chitosan/[Ti 2 W 10 PO 40 ] associates show a high hydrolytic stability at pH 7.4. The associates formed between the cluster anion [Ti 2 W 10 PO 40 ] 7) with the polyaminosaccharide chitosan have been characterized by photon correlation spectroscopy, scanning electron microscopy, filtration, centrifugation and zeta potential measurements. The size of the associates formed is in the range of ca. 5Â10 1 to 5Â10 2 nm. These particles have a defined stoichiometry with 5-6 cluster anions bound per molecule chitosan. The isoelectric point determined by zeta potential measurements was found for a cluster anion to chitosan molar ratio of 5.5, indicating the charge neutralization between protonated chitosan and [Ti 2 W 10 PO 40 ] 7) anions. Cellular uptake studies with [Ti 2 W 10 PO 40 ] 7) using tumor cell lines FaDu (human squamous carcinoma) and HT-29 (human adenocarcinoma) showed that the tungsten amount inside the cells is remarkably enhanced in the presence of chitosan.

Chitosan-Polyoxometalate Nanocomposites: Synthesis, Characterization and Application as Antimicrobial Agents

“…Bundles with ribbon-like substructure, which are particularly defined for CS/V 10 , can be observed. This behaviour is different from that observed with other procedures, that led to spherical POM/CS nanoparticles [38,40].…”

“…In addition, terminal/bridging oxygen on POM surface may accept hydrogen bonds from -OH and -NH 3 ? groups [37,38]. Such multiple intermolecular interactions result in the ionotropic gelation of the CS.…”

Interaction of Eu(III) with mammalian cells: Cytotoxicity, uptake, and speciation as a function of Eu(III) concentration and nutrient composition

“…They are adherent growing human squamous carcinoma cells, which are frequently and widely used in medical studies. As an example, Meißner et al (2006) studied the cellular intake of polynuclear polyoxometalates into FaDu cells as a prerequisite for applying photon activation therapy for cancer treatment. Laschinsky et al (2012) applied FaDu cells within the development of laser based particle acceleration for the use in cancer therapy.…”

Investigation of inorganic cluster–surfactant flocculants for virion sequestration and removal from aqueous media

“…While these hydrophobic POM phases (the SECs in particular) have been referred to as "bio-inspired," "biomimetic," or "bio-compatible" [16,[18][19][20], few applications or functionality that are biologically related have actually been demonstrated. However, there has recently been some focus on related polyoxometalate precipitates or LB films with cationic chitosan for cell entry [26] and anti-bacterial activity [8]. Scheme 1.…”