Functionalized Controlled Porous Glasses for Producing Radical-Free Hyperpolarized Liquids by Overhauser DNP

Abstract

Overhauser dynamic nuclear polarization (ODNP) can be used as a tool for NMR signal enhancement and happens on very short time scales. Therefore, ODNP is well suited for the measurement of fast-flowing samples, even in compact magnets, which is beneficial for the real-time monitoring of chemical reactions or processes. ODNP requires the presence of unpaired electrons in the sample, which is usually accomplished by the addition of stable radicals. However, radicals affect the nuclear relaxation times and can hamper the NMR detection. This is circumvented by immobilizing radicals in a packed bed allowing for the measurement of radical-free samples when using ex situ DNP techniques (DNP build-up and NMR detection happen at different places) and flow-induced separation of the hyperpolarized liquid from the radicals. Therefore, the synthesis of robust and chemically inert immobilized radical matrices is mandatory. In the present work, this is accomplished by immobilizing the radical glycidyloxy-tetramethylpiperidinyloxyl with a polyethyleneimine (PEI) linker on the surface of controlled porous glasses (CPG). Both the porosity of the CPGs and also the size of the PEI-linker were varied, resulting in a set of distinct radical matrices for continuous-flow ODNP. The study shows that CPGs with PEI-linkers provide robust, inert and efficient ODNP matrices.

Water-Insoluble, Thermostable, Crosslinked Gelatin Matrix for Soft Tissue Implant Development

“…These amino acids that build up gelatin, e.g., valine, leucine, isoleucine, and aspartic acid, have characteristic absorbance between 1502 and 1514 cm −1 [31]. Generally, the crosslinking via an epoxy crosslinker takes place between the carbon atom adjacent to the oxygen atom in the epoxy ring and the primary amino group [32], forming the molecules that are shown in Figure 10. In our case, these primary amines are peptides that were formed during the partial hydrolysis of collagen during the process of gelatin preparation; thus, they are presented as "R" groups.…”