Conductive carbon double faced adhesive tape

A scanning electron microscope (SEM; MIRA3, Tescan Orsay Holding, Brno, Czech Republic) equipped with a secondary electron detector was primarily used to observe the coating of capsules. The sample preparation for the microscopic measurement included a scalpel cross-section of the capsule and mounting the specimen on a SEM stub using a conductive carbon double-faced adhesive tape (Agar Scientific, Essex, UK). The next step was coating with a 20 nm gold layer using the metal sputtering coating method in the argon atmosphere (Q150R ES Rotary-Pumped Sputter Coater/Carbon Coater, Quorum Technologies, Laughton, UK). The SEM images were obtained at an accelerating voltage of 3 kV and various image view fields, while the image view field of 500 μm (or 1000 μm in one case) was chosen to observe the thickness of the capsule coating. The measurement was repeated 20 times from multiple images of each sample. DRcaps^TM and hard gelatin capsules without coating were also examined using SEM to determine the relations between the surface of uncoated capsules and polymer coating adhesion in the case of coated samples.

All samples were subjected to the examination of morphology by means of SEM. Pellet cross-sections were obtained by capturing a single pellet with tweezers and cutting it with a razor blade. The sample preparation for the microscopic measurement included mounting the specimen on a SEM stub using a conductive carbon double-faced adhesive tape (Agar Scientific, Essex, UK) followed by coating with a 20 nm gold layer using the metal sputtering coating method in the argon atmosphere (Q150R ES Rotary-Pumped Sputter Coater/Carbon Coater, Quorum Technologies, Laughton, UK). The sample images were taken with the utilization of a secondary electron detector (SED) at an accelerating voltage of 3 kV by means of a scanning electron microscope (MIRA3, Tescan Orsay Holding, Brno, Czech Republic).