Ar ion laser

PNIPAM microgels, in water suspension and at room temperature, were visualized with a differential interference contrast (DIC) filter under an optical microscope (Nikon Inverted Microscope Eclipse Ti-E, Nikon Instruments S.p.a, Florence, Italy) in transmission mode, by using a Plan Fluor 100.0x/1.30/0.20 oil immersion DIC H objective (Nikon), a DIC prism N2 (Nikon) and a Spectra Physics Ar⁺ ion laser (488 nm) as a light source. Fluorescent CS_05 and DC_05 microgels were characterized by confocal laser scanning microscopy (CLSM) by using the Nikon Inverted Microscope Eclipse Ti-E in confocal mode. The fluorescent probes covalently included in the microgels structures, Fluo-MA and Rhod-MA, were excited by the Ar⁺ ion laser (488 nm) (Spectra Physics, Santa Clara, CA, USA) and a Melles–Griot He–Ne laser (543 nm) (Lastek Pty Ltd, Thebarton, Australia), respectively. All images were captured using a Plan Fluor 100.0x/1.30/0.20 oil immersion objective and processed by using the EZ-C1 software (version 3.9, Nikon) and Image J freeware [45 ]. Fluorescent microgels were visualized in water suspension at room temperature, in the swollen state and in a 19.2% w/v PEG solution in the collapsed state under osmotic pressure application.

Structural investigations of SiNW-based samples were carried out by using a field emission scanning electron microscope (FE-SEM, Carl Zeiss ULTRA 55, Carl Zeiss, Jena, Germany) and a transmission electron microscope (TEM, LEO912 AB OMEGA, Carl Zeiss, Jena, Germany). A Malvern Zetasizer Nano ZS instrument (Malvern Instruments Ltd., Malvern, England, UK) was used to determine the size and zeta potential (ζ) of SiNPs obtained from data of dynamic light scattering (DLS). The surface composition of nanoparticles was studied by using a Fourier-transform infrared (FTIR) spectrometer Bruker IFS 66v/S, (Bruker, Karlsruhe, Germany) with a germanium prism for attenuated total reflection. Before recording FTIR spectra, the suspensions were dried in air on the prism surface. The FTIR measurements were done at room temperature in vacuum at a residual pressure of 10⁻³ Torr.
Additionally, the suspensions of SiNPs were characterised by using PL spectroscopy by excitation with an Ar-ion laser (wavelength 364 nm, power 10 mW, spot diameter 1 mm, Spectra-Physics, Stahnsdorf, Germany). The PL signal was detected using a grating monochromator (MS750, SOLAR TII, Moscow, Russia) equipped with a CCD array. The measurements were carried out at room temperature in air.