Experimental reflectance spectra were analyzed by applying a fast Fourier transform (FFT) using the software IGOR Pro (http://www.wavemetrics.com). Details of the analysis can be found in . In order to allow for a direct comparison of the effective optical thickness (EOT) values and FFT amplitude values from different pSi samples, all FFT spectra were normalized by setting the highest value equal to 1 and the lowest value equal to 0. Dynamic light scattering (DLS) measurements were carried out with a Malvern Instruments Zetasizer Nano ZS (Malvern Instruments, Malvern, UK). Refractive indices, dielectric constants, and viscosities of the ethanol/water mixtures were
taken JSH-23 concentration from literature [18, 19]. Atomic force microscopy (AFM) images were obtained with a JPK Nanowizard II (JPK Instruments AG, Berlin, Germany) in intermittent contact mode (cantilever: Veeco NP-S10, Plainview, NY, USA). Studies on the swelling behavior of the polyNIPAM spheres, attached to the porous silicon surface, were performed in liquid. PSi fabrication Si substrates were cleaned prior to etching by removal of a sacrificial layer of pSi with a strong base. For this purpose, Si substrates were anodized in a solution composed of 3:1 aqueous HF (48 %)/ethanol at 100 mA for 20 s. The resulting porous layer was removed by immersion in a 1 M
KOH solution for several minutes. Then, the Si samples were rinsed with ethanol and ARS-1620 immersed a second time in a 3:1 aqueous HF (48 %)/ethanol electrolyte. PSi monolayers were formed by electrochemically etching at 100 mA for ISRIB clinical trial 5 min. The resulting pSi was rinsed with ethanol and blown dry
in a stream of nitrogen. To stabilize the pSi, the samples were oxidized at 300°C for 1 h in an oven. PolyNIPAM microsphere synthesis PolyNIPAM microspheres were prepared by an aqueous free-radical precipitation polymerization according eltoprazine to Pelton and Chibante . Briefly, 0.19 mol/L NIPAM and 0.05 mol/L BIS were dissolved in 124-mL deionized water (approximately 18.2 MΩ cm). The solution was heated to approximately 70°C under inert atmosphere and stirring. Potassium peroxodisulfate (KPS) solution (0.002 mol/L) was added to start the polymerization, which continued for 6 h at approximately 70°C. The resulting polyNIPAM microspheres were purified by subsequent centrifugation, decantation, and redispersion in deionized water. The dispersion was finally filtered (Acrodisc 25-mm syringe filters with Versapor membranes (Pall GmbH, Dreieich, Germany), pore diameter 1.2 μm) and diluted 1:25 (v/v) with deionized water. Deposition of polyNIPAM spheres onto pSi Non-close packed arrays of hydrogel microspheres were deposited on pSi surfaces according to Quint and Pacholski . Briefly, 60 μL of the diluted polyNIPAM dispersion was placed on the oxidized pSi monolayer.