Enzymatic Adsorption and Degradation Rate of Thin Films

3 Enzymatic Adsorption and Degradation Rate of Thin Films 

To study the enzymatic degradation of the free amorphous region, completely amorphous PLLA thin film was prepared (see Section 22.3.2), and the erosion rate was directly monitored by using QCM in the nanogram per square centimeter regime [74]. The enzymatic erosion rate was dependent on the concentration of proteinase K, and the thin amorphous film of lOOnm thickness was completely hydrolyzed in 20 min when the concentration of the enzyme was 100 qg/mL. During the course of enzymatic degradation, even if the enzyme solution was replaced with a buffer solution (i.e.. 

FIGURE 22.11 AFM amplitude images of PLLA thin films (crystallized at 160°C) prepared from chloroform solutions with the concentrations of 0.25 (a), 0.5 (b), and 2.0% (w/v). The film thicknesses measured by AFM were 20 (a), 50 (b), and 200 nm (c), respectively, (a) Dendritic crystal, (b) hexagonal crystal, and (c) early stage of spherulitic morphology with edge-on and flat-on lamellae. Reprinted with permission from Ref. 65. Copyright 2001, American Chemical Society. 

FIGURE 22.14 AFM height and phase images of (a) PLLA amorphous thin film before enzymatic degradation, (b) proteinase K adsorbed on PLLA surface after enzymatic degradation for 7 min, and (c) PLLA surface washed with 40% aqueous ethanol after enzymatic degradation for 7 min. Reprinted with permission from Ref. 74. Copyright 2005, American Chemical Society. 

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