Synthesis of α,ω-bis-Mercaptoacyl Poly(alkyl oxide)s and Development of Thioether Cross-Linked Liposome Scaffolds for Sustained Release of Drugs.

With the aim to develop novel scaffolds for the sustained release of drugs, we initially developed an easy approach for the synthesis of α,ω-homobifunctional mercaptoacyl poly(alkyl oxide)s. This was based on the esterification of the terminal hydroxyl groups of poly(alkyl oxide)s with suitably S-4-methoxytrityl (Mmt)-protected mercapto acids, followed by the removal of the acid labile S-Mmt group. This method allowed for the efficient synthesis of the title compounds in high yield and purity, which were further used in the development of a thioether cross-linked liposome scaffold, by thia-Michael reaction of the terminal thiol groups with pre-formed nano-sized liposomes bearing maleimide groups on their surface. The reaction process was followed by 1H-NMR, using a Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion NMR experiment (1H-NMR CPMG), which allowed for real-time monitoring and optimization of the reaction process. The thioether cross-linked liposomal scaffold that was synthesized was proven to preserve the nano-sized characteristics of the initial liposomes and allowed for the sustained release of calcein (which was used as a hydrophilic dye and a hydrophilic drug model), providing evidence for the efficient synthesis of a novel drug release scaffold consisting of nanoliposome building blocks.

A customized light sheet microscope to measure spatio-temporal protein dynamics in small model organisms.

We describe a customizable and cost-effective light sheet microscopy (LSM) platform for rapid three-dimensional imaging of protein dynamics in small model organisms. The system is designed for high acquisition speeds and enables extended time-lapse in vivo experiments when using fluorescently labeled specimens. We demonstrate the capability of the setup to monitor gene expression and protein localization during ageing and upon starvation stress in longitudinal studies in individual or small groups of adult Caenorhabditis elegans nematodes. The system is equipped to readily perform fluorescence recovery after photobleaching (FRAP), which allows monitoring protein recovery and distribution under low photobleaching conditions. Our imaging platform is designed to easily switch between light sheet microscopy and optical projection tomography (OPT) modalities. The setup permits monitoring of spatio-temporal expression and localization of ageing biomarkers of subcellular size and can be conveniently adapted to image a wide range of small model organisms and tissue samples.