Physicochemical properties of epidermal growth factor receptor inhibitors and development of a nanoliposomal formulation of gefitinib.

Inhibitors of epidermal growth factor (EGF) receptor (EGFR) tyrosine kinases show efficacy in cancers that are highly addicted to nonmutated EGF signaling, but off-target effects limit therapy. Carrier-based formulations could reduce drug deposition in normal tissues, enhance tumor deposition, and reduce free drug concentrations, thereby reducing the side effects. Therefore, the feasibility of developing nanoliposomal formulations of EGFR inhibitors was investigated. Gefitinib and erlotinib fluorescence was characterized as a tool for formulation development. Peak excitation was 345 nm and peak emission was 385-465 nm, depending upon the environment polarity. Emission was negligible in water but intense in nonpolar solvents, membranes, or bound to serum proteins. Cellular uptake and distribution could also be imaged by fluorescence in drug-resistant tumor spheroids. Gefitinib fluorescence characteristics enabled facile optimization of formulations. Although 4-6 mol % gefitinib could be incorporated in the liposome bilayer, 40-60 mol % could be encapsulated in stable, remote-loaded liposomes consisting of distearoylphosphatidylcholine-polyethylene glycol-distereoylphosphatidylethanolamine-cholesterol (9:1:5 mol:mol:mol). Drug leakage in serum, monitored by fluorescence, was minimal over 24 h at 37°C. The results provide both promising lead formulations as well as novel tools for evaluating new formulations of structurally similar receptor tyrosine kinase inhibitors and their cellular uptake and tissue biodistribution.

Carbohydrate microarrays for the recognition of cross-reactive molecular markers of microbes and host cells.

We describe here the development of a carbohydrate-based microarray to extend the scope of biomedical research on carbohydrate-mediated molecular recognition and anti-infection responses. We have demonstrated that microbial polysaccharides can be immobilized on a surface-modified glass slide without chemical conjugation. With this procedure, a large repertoire of microbial antigens (approximately 20,000 spots) can be patterned on a single micro-glass slide, reaching the capacity to include most common pathogens. Glycoconjugates of different structural characteristics are shown here to be applicable for microarray fabrication, extending the repertoires of diversity and complexity of carbohydrate microarrays. The printed microarrays can be air-dried and stably stored at room temperature for long periods of time. In addition, the system is highly sensitive, allowing simultaneous detection of a broad spectrum of antibody specificities with as little as a few microliters of serum specimen. Finally, the potential of carbohydrate microarrays is demonstrated by the discovery of previously undescribed cellular markers, Dex-Ids.