Field emission gun

The presence of bacteria and overall biofilm formation on each of the three different types of occluders was evaluated by SEM. Prior to SEM, each occluder was washed three times (5 min each time) in 1× Phosphate Buffer Saline (PBS). The occluders were then dehydrated serially in alcohol washes, as follows: 70%, 80%, 90% (15 min at RT) and 100% (three times for 15 min at RT). Images were obtained on a LEO 1550 Field Emission Scanning Electron Microscope (Carl Zeiss AG, Oberkochen, Germany), with a Schottky Field Emission Gun, at an acceleration voltage of 20 kV and a Robinson Back Scatter Detector. Occluders were gold coated to prevent charging effects.

The samples
were prepared by spin-coating the HTM solution in chlorobenzene onto
a FTO film (2000 rpm, 20 s); they were then irradiated by a 450 W
Xe lamp filtered through a double monochromator (5 nm bandpass). The
film morphology was investigated by using a high-resolution scanning
electron microscope (SEM) (Merlin, Zeiss) that was equipped with a
GEMINI II column and a Schottky field emission gun. Images were acquired
with an in-lens secondary electron detector. For the PL lifetime measurements,
samples were excited with a 408 nm pulsed laser (MDL 300, PicoQuant)
with a 40 μm cm² pulse energy density. Current–voltage
characteristics were recorded by applying an external potential bias
to the cell while recording the generated photocurrent with a digital
source meter (Keithley Model 2400). The light source was a 450 W Xe
lamp (Oriel), equipped with a Schott K113 Tempax sunlight filter (Präzisions
Glas & Optik GmbH) in order to match the emission spectrum of
the lamp to the AM1.5G standard. Before each measurement, the exact
light intensity was determined by using a calibrated Si reference
diode that was equipped with an infrared cutoff filter (KG3, Schott).
The cells were masked with an active area of 0.09 cm².
Contact angle measurements were done with the help of a DSA30 drop
shape analyzer instrument and analyzed with the help of the Krüss
ADVANCE software.

The cured plates have been imaged using a Zeiss Merlin scanning electron microscope (SEM), equipped with a Schottky field emission gun. The SEM images were acquired collecting the secondary electron (SE) signal, with the microscope working at an acceleration voltage of 5 kV, a beam current of 100 pA, and by using the in-chamber SE detector. All samples were sputter-coated with an Iridium layer of 4 nm-thickness before SEM analysis.
Surface roughness was determined using a contact profilometer (Sutronic 25, Taylor Hobson, UK). A gauge length of 4 mm was selected, while the hardware’s measurement resolution was equal to 100 μm. A minimum number of three scans was carried out to ensure redundancy and consistency of the obtained results. Measurements were done in the directions parallel (0 ${}^{\circ }$ ) and perpendicular (90 ${}^{\circ }$ ) to the orientation of the fibers, and the arithmetical mean deviation $R_a$ (i.e., the average deviation of all points of the roughness profile from a mean line over the evaluation length) was determined as suggested in UNI ISO 4287 [25 ]: $R_a=\frac{1}{n}\sum _{j=1}^n\left|r_j\right|,$
where n is the number of sampling points and $r_j$ is the height of the surface profile with respect to the reference plane. The average of these measurements ( $S_a$ ) was employed to present the obtained results: $S_a=\frac{R_{a,x}+R_{a,y}}{2}.$