Dynamic nuclear polarization (DNP) [1] combined with magic angle spinning (MAS) [2] can-under favorable conditions-enhance the nuclear spin polarization, that is, the difference between the populations of the Zeeman levels j ai and j bi of a spin I = 1 = 2 by up to two orders of magnitude (e DNP 10 2 ) with respect to the Boltzmann distribution at thermal equilibrium at ca. 100 K, while accelerating relaxation and hence reducing recovery delays by more than an order of magnitude (k = R DNP / R 1 = T 1 /t DNP > 10), thus providing a means of shortening measurement times by up to five orders of magnitude. Where suitable solvents can be found, typical enhancements for 13

Two novel types of hydrogel microspheres (MS) are presented. First, one-component microspheres (1-comMS) were produced from sodium alginate (Na-alg) equipped with thiolfunctionalized hydroxyl groups. The functionalization pathway included the conversion of Na-alg into tetrabutylammonium alginate, insertion of new carboxyl groups, grafting of α-amine-ωthiol poly(ethylene glycol), and restoration of the sodium salt. This modification conserves all original carboxyl groups of Na-alg and allows for covalent disulfide bond formation in addition to ionic cross-linking. Second, two-component microspheres (2-comMS) were obtained from a mixture of Na-alg and Na-alg functionalized with cysteamine. This functionalization was achieved by grafting cystamine dihydrochloride on some carboxyl groups followed by the reduction to cysteamine. Using the one-step MS formation process developed for both MS types, very fast ionic gelation with calcium ions conserves the spherical shape of the polymer solution droplets upon extrusion into the gelation bath, while simultaneously occurring slow covalent cross-linking reinforces the hydrogels. The physical properties of both MS types are adjustable by varying the polymer concentration, the degree of grafting, and the mixing ratio. In vitro cell microencapsulation studies confirmed the cytocompatibility of 1-comMS and 2-comMS.

The

Different anchoring groups have been studied with the aim of covalently binding organic linkers to the surface of alumina ceramic foams. The results suggested that a higher degree of functionalization was achieved with a pyrogallol derivative − as compared to its catechol analogue − based on the XPS analysis of the ceramic surface. The conjugation of organic ligands to the surface of these alumina materials was corroborated by DNP-MAS NMR measurements.

To control the selective adhesion of human endothelial cells and human serum proteins to bioceramics of different compositions, a multifunctional ligand containing a cyclic arginine-glycine-aspartate (RGD) peptide, a tetraethylene glycol spacer, and a gallate moiety was designed, synthesized, and characterized. The binding of this ligand to alumina-based, hydroxyapatite-based, and calcium phosphate-based bioceramics was demonstrated. The conjugation of this ligand to the bioceramics induced a decrease in the nonselective and integrin-selective binding of human serum proteins, whereas the binding and adhesion of human endothelial cells was enhanced, dependent on the particular bioceramics.