Sputter coater

Microstructure of flours was studied using a scanning electron microscope (Merlin, Carl Zeiss, Germany). Flours were adhered to stubs using a double-sided carbon tape and viewed at 5 kV and 1400X after being coated with gold using a sputter coater (Quorum Technologies, Lewes, UK).

A 0.1% solution of prepared NPs was made by diluting 0.001 g of NPs in 1 mL of Milli-Q^® water. The prepared 0.1% solution was further diluted to 10⁴ by serial dilution. Finally, the obtained NP solution was mixed well, and the particle size was analyzed by dynamic light scattering (DLS) using Malvern Mastersizer. Lyophilized NPs were gently placed and distributed on a carbon tube, which was placed on an aluminum-based scanning electron microscopy (SEM) stub. The samples were then gold coated in a sputter coater (Quorum Technologies Ltd, Laughton, UK) for 60 seconds to avoid charging of the samples. SEM was performed for all the NPs using a Supra™ 55 variable pressure electron microscope. NP samples were crushed finely in an agate mortar and pestle, were mixed with potassium bromide (KBr), and were finely ground. Finally, the mixture was placed into a pelletizer to form the KBr disc containing the sample. The KBr disc was then analyzed using a Bruker Fourier transform infrared (FTIR) Vertex 70 spectrophotometer and Opus version 5.5 software (Bio-Rad Laboratories Inc, Hercules, CA, USA; Bruker Optics Inc, Billerica, MA, USA; Opus, Inc, Houston, TX, USA) in the wave number range of 400 to 4,000 cm⁻¹.

The labeled DNA was bound to a magnetic bead of 2.8 or 5 μm in diameter and to anti-digoxigenin-coated glass. The glass was kept horizontal and the liquid sample was held on it by surface tension. The DNAs were stretched by the magnetic field. The sample was then stained with 0.25 mg mL⁻¹ cytochrome C and 50% formamide, followed by gentle washing with pure water. The magnetic field was rotated by 90 degrees and kept steady to align the DNA molecules along the surface of the glass (Fig. 1A).
Rosette samples were prepared as described for light microscopy experiments. The cover glass was kept horizontal. A permanent magnet was placed at the side of the sample and was used to pull the cell parallel to the surface of the glass. The samples were rinsed with pure water twice. Samples were then fixed with 8% glutaraldehyde and washed gently with pure water, as described in our previous report.^{28 (link)}The samples were dried in a desiccator. A Sputter Coater (Quorum) was used to coat a platinum film onto the glass surfaces for 60 s in the vacuum. SEM images were obtained for fine structures after stretching, using a Zeiss Merlin field-emission SEM operated at a 5 kV accelerating voltage. The images were measured using ImageJ software (National Institute of Health).