Page 153 - Synthesis of Functional Nanoparticles Using an Atmospheric Pressure Microplasma Process - LiangLiang Lin

Plasma-Liquid Synthesis of Silver Nanaoparticles and Anti-bacteria Activity Study - Introduction to Bio-application
Figure 8.1 Schematic of microplasma-assisted setup for Ag nanoparticles synthesis. 8.2.2 Characterization
The obtained products in the reaction medium were characterized by an ultraviolet-visible a absorbance spectroscopy using a SHIMADZU UV-2500 spectrometer. All measurements were carried out in quartz cuvettes. Meanwhile, spectra of solutions without plasma treatment were also collected as comparison. The mass of the synthesized Ag nanoparticles was calculated from the calibration curves which were determined using series of dilution steps from standard solution of Ag nanoparticles (particle size of 10 and 30 nm, Alfa Aesar) with known concentration. This can be compared with the total number of silver cations from molar concentration in solution, then the conversion efficiency (already for precursor) can be estimated. TEM samples were prepared by directly casting one drop of resultant solutions on carbon-coated Cu TEM grids (Quantifoil Micro Tools, GmbH) and dried under vacuum. The crystalline structures were furtherly characterized by XRD using a Rigaku Powder Diffractometer (Cu-Kα1 radiation, λ=1.54056 Å). All diffraction patterns were recorded in a 2q step of 0.02° and a dwell time of 20s.
8.2.3 Antibacterial Test
For the antibacterial test, approximately 106 colony forming units per milliliter (CFU/ml) of E. coli (DH5α) were exposed to a serial dilution of the AgNPs (from 10 to 90 μg/ml) in Luria- Bertani (LB) medium. The cultures were incubated at 37 °Cand shaken at 250 rpm, then the samples treated with Ag nanoparticles after 16h were spread on LB agar plates and incubated at 37 °Cfor 24 h. Silver-free and bacterium-free LB plates cultured under the same conditions were used as the positive and negative control.
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