S 4300 scanning electron microscope

For scanning electron microscopy (SEM), static cultures were grown in 50-ml conical tubes with circular glass coverslips semi-submerged in 2 ml of LB broth. Coverslip samples were handled and processed as described previously (Gaddy et al., 2009 (link)). Upon removal of the culture medium, the coverslips were immediately flooded with 2.5% glutaraldehyde in 0.05 M sodium cacodylate and incubated at room temperature for 1 h. The fixative was then removed and replaced immediately with 0.05 M sodium cacodylate to prevent sample dehydration. Next, the coverslips were incubated in osmium tetroxide for 15 min followed by dehydration with increasing concentrations of ethanol, ranging from 25 to 100%, and CO₂ critical point drying. Samples were carbon-coated and visualized with a Hitachi S-4300 scanning electron microscope.

A Hitachi S-4300 scanning electron microscope was used to acquire cross-sectional images of target samples.

¹H and ¹³C-NMR spectra were measured on a Bruker Avance DRX600 spectrometer (Bruker, Billerica, MA, USA). Spot absorption spectra were obtained by use of a DXRxi Raman Imaging Microscope (Thermo Fisher Scientific, Waltham, MA, USA) with an excitation wavelength of 532 nm and 50 μm confocal pinhole diaphragm. Fourier transform infrared spectroscopy (FT-IR) was measured on a Bruker Equinox 55 Fourier transform infrared spectrometer (Bruker, Billerica, MA, USA). Scanning electron microscope (SEM) images were carried out using a HITACHI S-4300 scanning electron microscope (Hitachi, Tokyo, Japan). Thermo gravimetric analysis (TGA) was carried out with a Pyris-Diamond TGA (PerkinElmer, Boston, MA, USA). Ultra high performance liquid chromatography (UHPLC) was carried out with an American Waters Acquity UHPLC Class (Waters, Milford, MA, USA).

Purified lactomicroselenium particles were fixed for 30 min at 0 °C with 2.5% glutaraldehyde in PBS. After washing with the same buffer nanoparticles were fixed for a further 30 min at 0 °C with 2.5% osmium tetroxide in the same buffer. Nanoparticles were dehydrated stepwise, using increasing concentrations of ethanol in the rage of 50%–100% and were coated with gold for viewing by a Hitachi S 4300 scanning electron microscope (Schaumburg, IL, USA).

Transmission electron microscopy (TEM) images were taken on a JEOL JEM-2100F transmission electron microscope at 200 kV. Samples for TEM observations were prepared by first dispersing silica nanoparticles in ethanol by ultrasonication, followed by dropping on holey carbon-coated copper grids and drying at room temperature. The morphology and roughness of coating surfaces were characterized by atomic force microscopy (AFM) on a MM8-SYS scanning probe microscope (Bruker AXR) and scanning electron microscopy (SEM) on a Hitachi S-4300 scanning electron microscope operated at 10 kV. Transmission spectra in the wavelength range of 330–800 nm were recorded using a TU-1901 spectrophotometer (Beijing Purkinje General Instrument Co.). Reflection spectra in the wavelength range of 400–800 nm were recorded on a Varian Cary 5000 UV/Vis-NIR spectrophotometer. Water contact angles on the surface of different specimens were measured at ambient temperature on a Kino SL200B3 automatic contact angle meter. For the examination of antifogging property, the ISNW20-SNs/polymer/PET was cooled at ca. −6 °C for 24 h in a refrigerator, and then exposed to humid laboratory air (temperature: 20–30 °C, relative humidity: 20–40%).

A dilution of S. mutans cultured overnight (OD₅₉₅ of 0.05) in BHI medium containing 10 μM sucrose was incubated with glass slides at 37°C for 24 h. Biofilm cells on the slides were fixed with 4% glutaraldehyde solution (Sigma-Aldrich) at 4°C for 1 h. Then, the fixed biofilm cells were sequentially dehydrated in 50%, 80%, and 100% ethyl alcohol for 20 min each. Dehydrated biofilm cells were dried in a vacuum desiccator for 12 h and coated with platinum for 90 s using an E-1030 ion-sputter coater (Hitachi, Tokyo, Japan). The coated sample was observed using a model S-4300 scanning electron microscope (Hitachi) operated at a magnification of ×5,000 and a voltage of 15.0 kV.