Scanning Electron Microscopy
We used scanning electron microscopy (SEM) to qualitatively investigate
how biological matter attaches to each of the different materials.
Scanning electron microscopy uses a focused beam of high-energy
electrons to generate a variety of signals at the surface of solid
specimens. These signals are converted into 2-dimensional
high-resolution images and reveal information about the external
morphology (texture), chemical composition, and crystalline structure
and orientation of materials making up the sample. A subsection of each
membrane material was dissected using sterile surgical scissors and
mounted onto 10 mm dimeter SEM stubs with an adhesive carbon tab to
prevent charge build-up. The stubs were then air dried at ambient
temperature in a fume hood while partially covered to prevent dust or
debris on the samples. Once completely dry, samples were coated with a
thin layer of platinum (sputter coated with 3 nm of platinum using a
Leica EM MED020; Leica Microsystems, Inc. Buffalo Grove, IL); a fine
conducting material for high resolution electron imaging. The samples
were visualized and imaged on a Zeiss 1555 VP-FESEM with SmartSEM
software (Zeiss, Germany) at the Centre for Microscopy, Characterisation
and Analysis (CMCA), University of Western Australia, Perth, Western
Australia. We provide example SEM images of materials at 10,000 x
(cellulose) and 100 x (cotton, hemp, sponge – active carbon and sponge
- nitrate) magnification prior to deployment (Table 1) and provide an
example of all deployed materials with biological matter attached. Due
to limited supplies of chitosan and electrospun nanofiber covered
cellulose membranes, none were available for SEM imagining prior to
deployment.