Em scd005 gold coater

Hair and feather samples treated with Cibenza DP100 and Ronozyme ProAct for 2, 6, 10 and 16 h at 37°C, with or without reducing agent (1% sodium sulfite or 2% sodium thioglycolate), were centrifuged and air dried for several days, fixed in a sample holder stub and gold coated using a Leica EM SCD005 Gold Coater (to ~ 10 nm). Secondary electron images were obtained with Zeiss ∑igma Field Emission Scanning Electron Microscope. Images were obtained under vacuum using 2 kV accelerating voltage.

The surface morphological studies of DPI formulations were investigated using a scanning electron microscope, Tescan Mira3 (Brno, Czech Republic). Using the same machine and Image J software, micronized inhalable particles were visualized. DPI formulations were dusted individually on a metal sample stub with a double-sided adhesive carbon tape attached on its surface. After sprinkling the samples on the top of the adhesive carbon tape, excess particles from the carbon tape surfaces were removed by blowing compressed nitrogen gas. Using a sputter coater, each sample was coated with a conductive layer of gold (Leica EM SCD005 gold coater) with argon gas at 0.5 mbar pressure for 70 to 75 s. The purpose of the gold coating was to prevent surface charging and reduce thermal damage of the particle during imaging at 5 kV.