Cationization of heparin for film applications

Trimethylammonium-2-hydroxypropyl-(TMAHP) spacer was introduced into heparin (H) and the prepared films were characterized by elemental analysis, NMR, SEC-MALS, TG/DTG/DTA, AFM and mechanical tester. When quaternized at the ratio of H/NaOH/alkylating agent/H2O = 0.1-1/0-2/0.1-1/50-500 mmol, H was substituted at A6 and A3 positions. The formation of double-substituted structures by substitution of free hydroxyl group of the previously introduced TMAHP substituent is evident. In the absence of NaOH (H/GTMAC/H2O = 1:1:500) the most drastic decrease of Mn to 8.639 kg/mol and Mw/Mn at 1.48 was observed in comparison to H (Mn = 9532 g/mol with Mw/Mn = 1.38). The film mechanical properties were better on H (E = 4030 MPa; σb = 65 MPa; ɛb = 4.6%) than on quaternized specimens (E = 2500-3340 MPa; σb = 25-40 MPa; ɛb = 1.7-1.8%). The AFM images did not prove relation between mechanical properties and surface shape.