Molecular design and evaluation of biodegradable polymers using a statistical approach.

The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required.

Water confinement in hydrophobic nanopores. Pressure-induced wetting and drying.

Wetting and drying of hydrophobic pores with diameters lower than 0.2 μm by aqueous solutions at different hydrostatic pressures is investigated by measuring the ionic conductance variation through the nanopores. The critical pressure for water intrusion into the nanopores increases with lowering the pore diameter and the surface tension of the hydrophobic modification, in agreement with the Laplace equation.

Biochemically responsive smart surface.

A design of smart surfaces responsive to biochemical analytes is demonstrated in the example of mixed monolayers of biotin/fluorocarbon. The contact angle of aqueous solutions on such surfaces decreases upon streptavidin binding and can be used in detecting this protein. The specificity of the effect is confirmed by the lack of a contact angle change by streptavidin blocked with biotin and by bovine serum albumin.

Electrical conductance of hydrophobic membranes or what happens below the surface.

Nanoporous alumina membranes rendered hydrophobic by surface modification via covalent attachment of hydrocarbon or fluorocarbon chains conduct electricity via surface even when the pores are not filled with electrolyte. The resistance is many orders of magnitude higher than for electrolyte-filled membranes and does not depend on the electrolyte concentration or pH, but it does depend on the type of hydrophobic monolayer and its density. The corresponding surface resistance varies from greater than 10(18) Omega per square to less than 3 x 10(9) Omega per square.