Sputter coater 108 auto

The cellular interaction with the fibrous membranes was visualized using scanning electron microscopy (SEM) (TESCAN Mira 3 LM field emission, Czech Republic). The samples were fixed using a PBS solution containing 2.5 vol.% glutaraldehyde and 2 vol.% PFA for 1 h. Following three washes with water, the samples were dehydrated using a series of alcohol washes (20, 30, 50, 70, 80, and 100 vol.% ethanol) for 10 min each before being treated with a solution of HMDS in ethanol (1:1 volume ratio). Before imaging, the samples were left to dry for 3 days and sputter-coated with 3 nm of gold (Sputter Coater 108 Auto, Cressington Scientific Instruments, Watford, UK).

A microscopic analysis of structural changes of the film surface was carried out using an SEM (Hitachi SU 8010, Japan). Fragments were cut from the 30 ×30 mm samples, and then sprayed with gold to a thickness of 1 nm using a gold dust sprayer (Cressington Sputter Coater 108 auto, UK) with a dust-layer thickness meter (Cressington Thickness Monitor mtm10, UK). Pictures were taken at 1000 × magnification. Energy Dispersive X-ray analysis (EDX) was performed using the SEM-EDX module (Thermo Scientific Ultra Dry, USA). The EDX spectrum of the sample surface allowed a semi-quantitative analysis of the elementary composition to the depth of ca. 1 μm (Varesano, Dall’acqua & Tonin, 2005 (link)). During the EDX analysis, a voltage of 20 kV and current of 15 μA was applied to the prepared samples. The analysis of the elemental composition of the surface lasted 30 s at ×100 magnification and a working distance of 15 mm. The experiment was repeated in 5 replicates for each variant containing either PLA or PET film.

SEM images were obtained using a field-emission scanning electron microscope (Inspect F50, FEI, USA) at an accelerating voltage of 10.0 kV, after Pt coating (sputter coater 108auto, Cressington Scientific Instruments, UK). Transmission electron microscopy image and selected area electron diffraction patterns of the rectangular plate foldectures F2 were obtained using a transmission electron microscope (Tecnai G2 30, FEI, USA) operated at 200 kV. Samples were deposited on a formvar carbon film on a 200-mesh copper grid (Electron Microscopy Sciences, USA). Optical microscopy movies were recorded using a three-dimensional digital microscope system equipped with a charge-coupled device camera (KH-8700, Hirox, Japan).

MSM samples were submerged in a jam jar filled with tap water to a height of about 1.5 cm, i.e., below h_max to allow for a persistent air layer. The jar was closed and stored on a rack in the office. After one month, the samples were taken out of the water and dried in air. The dried samples were mounted to aluminum stubs and fixated using silver paste. To enhance the conductivity, the samples were sputtered with a thin gold layer (thickness 20 nm, Sputter Coater 108 auto, Cressington, Dortmund). Afterwards the samples have been analyzed using SEM (15 kV, CAMBRIDGE Stereoscan 200 SEM, Zeiss AG, Oberkochen).

The morphology of the composite surface was examined by scanning electron microscopy (SEM; Hitachi SU3500, Tokyo, Japan) at 5 kV under high-vacuum conditions. The small cut of each sample was applied to the aluminum stage covered by carbon tape. Next, the samples were coated with an ultrathin gold layer (Au) using an ion-sputtering machine (Cressington Sputter Coater 108 Auto, Watford, UK).