Tesp v2 cantilever

PEMs were prepared for atomic force microscopy imaging as described in the previous section. After the LbL assembly, samples were rinsed with nanopure water and left to dry in air. The morphology of PEMs was obtained using an AFM from Nanowizard II AFM (JPK, Berlin, Germany). Images were collected in tapping mode with TESP-V2 cantilever (Bruker, AFM Probes) with nominal spring constant of 40 N m -1 and oscillated near a resonant frequency in the range of 280 to 320 kHz.

Structural details of the collagen-alginate films were investigated using a Nanowizard II AFM (JPK, Berlin, Germany) and a Nanoscope V Multimode AFM (Santa Barbara, CA). Tapping mode imaging was performed in liquid (PBS or Na acetate buffers) using a DNP-S10A cantilevers (Bruker, Berlin, Germany) with a nominal spring constant 0.350 N m À1 and resonant frequency at B13 kHz. In order to measure the height of the films, nanolithography was performed on a Nanowizard II AFM with TESP-V2 cantilever (Bruker, Berlin, Germany) with a nominal spring constant of 40 N m À1 and the resonant frequency was B130 kHz. Lithography was achieved by defining an area of 8 mm  2 mm that was rasterized in contact mode at 160 mm s À1 and subsequently imaged. This was repeated several times, until a smooth surface of the substrate could be observed and no increment in the height of the film edges could be seen. After performing nanolithography, tip direction was rotated for 901 to acquire images and measure height profiles.