Ccd camera

Pioloform-coated copper grids (G2440C) from Plano (Wetzlar, Germany) were incubated with 0.1% poly-l-lysine at 23 °C for 30 min, rinsed with water, and dried under dust-free atmosphere. A droplet of 20 µL of the sample was pipetted on the grids. After 20 min, the grids were rinsed with water and left for drying. Afterwards, the samples were directly investigated in the transmission electron microscope (TEM). TEM images were acquired with a Philips CM10 instrument, coupled with a CCD camera (IDS, Obersulm, Germany), at an acceleration voltage of 80 kV.
For visualization and measurement of the mNP protein corona thickness, the samples must be negatively stained. Therefore, the samples were treated with a saturated ethanolic uranyl acetate solution for 2 min. Excess liquid was removed, and the samples were dried again before TEM analysis. Particle dimension and thickness of the protein corona were evaluated using the software ImageJ [73 (link)], and the size distribution of 45 individual particles was analyzed. For determining the thickness of the protein corona 20 individual particles were analyzed.

A piece of retina was placed photoreceptor side up in a recording chamber (RC27L, Warner Instruments, Hamden, CT, USA) and superfused with Ames’ medium (Sigma, sSt Louis, MI, USA) at 37 °C. The recording chamber was mounted on a Nikon FN600 (Tokyo, Japan) equipped with IR illumination and a CCD camera (Philips, The Netherlands). Electrodes were made from borosilicate glass (GC150TF-10, Harvard Apparatus Ltd., Holliston, MA, USA), pulled to 3–6 MΩ using a Brown Flaming Puller (Model P-87; Sutter Instrument, Novato, CA, USA), and filled with a solution containing 13 mM KCl, 82.4 mM K-Gluconate, 1 mM MgCl₂, 0.1 mM CaCl₂, 1 mM EGTA, 10 mM HEPES, 10 mM ATP-K₂, 1 mM GTP-Na₃, 20 mM phosphocreatine-Na₂ and creatine phosphokinase 1.54 mg/100 mL. Electrodes were mounted on a MP-85 Huxley/Wall-type micromanipulator (Sutter Instrument, Novato, CA, USA) and whole cell recordings were made using a DAGAN 3900A integrating patch clamp amplifier (Dagan Corporation, Minneapolis, MN, USA), a 1401 CED AD/DA converter (Cambridge electronics, Cambridge, UK) and a PC running Signal (Cambridge Electronics, Cambridge, UK). Leak currents were estimated by linear extrapolation using the whole cell current occurring immediately after the capacitance transient, but prior to I_h activation, for voltage steps from −70 mV to −45 mV (5 mV steps). In each case R² > 0.99.

250-mesh carbon coated copper grids were placed for 60 s onto 10 μl of sample droplets containing Tau fibrils (10 μm). Thereafter, liquid was removed and grids placed for 60 s onto 10 μl droplets of 2% uranyl acetate. The grids were air-dried on filter paper and images recorded with a Philips/FEI Tecnai-12 transmission electron microscope at 80 keV equipped with a Gatan CCD camera.