( A ) Scheme of AND and NAND logic gates principle. ( B ) Fluoresent spectra of (a) SC-dots only, (b) SC-dots/ct-DNA, (c) SC-dots/ct-DNA/EB, (d) SC-dots/EB, excitation wavelength: 400 nm. On excitation at 400 nm, fluorescence output at 585 and 465 nm were recorded in AND and NAND gates, respectively. ( C ) Truth table. ( D ) AND/NAND logic scheme.