Five microliters of protein solution containing liquid-like droplets or nanofibers was dropped on a piece of clean glass slide (1.0 ± 0.2 mm in thickness; Citoglas) and then covered by a piece of cover glass (0.13 to 0.16 mm; microscopic cover glass, Citoglas). DIC imaging was performed on a ZEISS Z2 microscope equipped with Axiocam 506 camera (ZEISS). The 3D confocal images of microfluidic channel or microtubule were obtained with a Leica TCS SP8 confocal microscope. The 561-nm laser was used for excitation of QDs. Data are presented in Figs. 2F and 4 (C and D).