Biofunctional Materials Based on Amino Cellulose Derivatives--A Nanobiotechnological Concept.

This feature article summarizes recent developments in the field of so-called aminodeoxy cellulose derivatives ("amino celluloses") that are applied for functional surface coating of biofunctional materials. After introducing common manufacturing methods for nanostructurized substrates (material surfaces and nanoparticles) biorelevant amino celluloses are described. It could be demonstrated that cellulose is a unique starting material for chemical modification of hydroxyl groups and the adjacent carbon atom. Amino celluloses are proved to be the modifiable polymer of choice for the biofunctionalization of material surfaces. Amino celluloses possess self assembling properties and may form monolayer composites on a variety of substrate materials.

Polystyrene-block-polyglycidol micelles cross-linked with titanium tetraisopropoxide. laser light and small-angle X-ray scattering studies on their formation in solution.

Hybrid micelles from polystyrene-block-polyglycidol (PS-b-PG) copolymers with chemically cross-linked cores by titanium tetraisopropoxide (Ti(OC(3)H(7))(4)) were prepared in toluene solution. Additionally, micellization of PS-b-PG copolymers with different mass fractions of polyglycidol (x(PG)), was studied by static and dynamic light scattering as well as small-angle X-ray scattering. It was observed that copolymers with x(PG) smaller than 0.5 self-assembled in toluene into spherical core-shell micelles with hydrodynamic radii R(h) between 12 and 23 nm. On the other hand, copolymers with larger PG content formed particles with R(h) = 50-70 nm and aggregation numbers of several thousands. The presence of these aggregates in solution was attributed to the nonequilibrated form of block copolymers upon dissolving, most probably due to hydrogen bonding. In the following, spherical PS-b-PG micelles were loaded in toluene with hydrochloric acid and titanium tetraisopropoxide. Confined hydrolysis of Ti(OC(3)H(7))(4) induced by HCl in the micellar core was confirmed by small-angle X-ray scattering experiments. The subsequent condensation of the precursor with hydroxyl groups of polyglycidol chains led to covalently stabilized hybrid organic-inorganic particles. The presence of cross-linked PS-b-PG micelles was proven in two ways. First, micelles with "frozen" core showed stable hydrodynamic size in time upon dilution below critical micellization concentration while non-cross-linked PS-b-PG micelles underwent disintegration under the same conditions within several hours. Second, light scattering experiments revealed the presence of stable, swollen particles in N,N-dimethylformamide, which is a good solvent for both blocks.

One-pot cyclizations of dilithiated oximes and hydrazones with epibromohydrin. Efficient synthesis of 6-hydroxymethyl-5,6-dihydro-4H-1,2-oxazines and oxazolo[3,4-b]pyridazin-7-ones.

The one-pot cyclization of dilithiated oximes with epibromohydrin provided a convenient and regioselective approach to 6-hydroxymethyl-5,6-dihydro-4H-1,2-oxazines. The reaction of the latter with phosphorus tribromide resulted in a Beckmann rearrangement and formation of 5-bromomethyl-2-iminotetrahydrofurans. The reaction of dilithiated hydrazones with epibromohydrin afforded oxazolo[3,4-b]pyridazin-7-ones, which were formed by a novel domino cyclization.