Precision coating system

The electrospun mats were sputter-coated with gold using a precision coating system (Gatan, Pleasanton, CA, USA) and the morphology of PCL, PCL10% HA, and PCL15% HA were observed using a scanning electron microscope (FEI Quanta 400, Hillsboro, OR, USA) under an accelerating voltage of 10 kV. The images were analyzed using image analysis software, Digimizer.

The size and shape of curli fiber units formed in the QCM-D flow chamber on gold sensor surfaces were visualized by scanning electron microscopy (SEM) and fluorescence microscopy. For the SEM (FEI, USA) imaging studies, samples that were drop cast on silica or gold substrates were first air-dried and sputter coated with 5 nm of Au/Pd alloy using a precision coating system (Gatan Inc, USA). Imaging was performed under high vacuum conditions with an electron beam energy of 5-15 KeV. Fluorescence microscopy studies were performed with an Axio Scope A1 (Zeiss, Germany) with excitation wavelengths of 546 nm for red, 455 nm for green and 365 nm for blue fluorescence and emission wavelengths of 575-640 nm, 500-550 nm and 420-470 nm, respectively. Fluorescence intensity exposure times were equal for the same area across different emissions.