Iron oxide particles covered with hexapeptides targeted at phosphatidylserine as MR biomarkers of tumor cell death.

The aim of the study was to evaluate the ability of a new MR contrast agent to detect cell death as a biomarker of the efficacy of anti-cancer treatment. The phosphatidylserine-targeted hexapeptide (E3) was coupled to pegylated ultrasmall iron oxide nanoparticles (USPIO) that can be detected by magnetic resonance imaging (MRI) and by electron paramagnetic resonance (EPR). USPIO binding to staurosporine-treated TLT (transplantable liver tumor) cells, evaluated by X-Band EPR, indicated twice as much binding of USPIO grafted with the E3 peptide, compared with USPIO grafted with a scrambled peptide or ungrafted USPIO. In vivo experiments were carried out using TLT cells implanted intramuscularly into NMRI mice, and tumor cell death was induced by irradiation. After intravenous injection of the different types of USPIO, the accumulation of contrast agent was evaluated ex vivo by X-band EPR, in vivo by L-band EPR and by T(2)-weighted MRI. In irradiated tumors there was greater accumulation of the targeted USPIO particles compared with control particles or compared with the targeted particles in untreated tissues. In conclusion, phosphatidylserine-targeting of USPIO particles can detect dying tissues. This molecular targeted system should be evaluated further as a potential biomarker of tumor response to treatment.

Enzymatically prepared n-alkyl esters of glucuronic acid: the effect of freeze-drying conditions and hydrophobic chain length on thermal behavior.

In this work, some of the physicochemical properties of enzymatically prepared n-alkyl esters of glucuronic acid are presented. Two questions are addressed. The first concerns the influence of post-purification freeze-drying conditions on octyl glucuronate thermotropic behavior. Depending on the amount of water added before freeze-drying, the alpha/beta anomeric ratio determined by (1)H NMR is affected and differences are observed in DSC thermograms probably due to polymorphism. The second question concerns the effect of hydrophobic chain length on the thermal behavior. An increase of both transition temperature and transition enthalpy is observed by increasing the number of carbon atoms in the alkyl chain (C8