Abstract: Fluorescent nucleobase surrogates capable of Watson-Crick hydrogen bonding are essential probes of nucleic acid structure and dynamics. Their limited brightness and short absorption and emission wavelengths have rendered them unsuitable for single-molecule detection. Herein, we synthesized a new tricyclic pyrimidine nucleoside analogue with a push-pull conjugated system. The resulting C-linked 8-(diethylamino)benzo[b][1,8] naphthyridin-2(1H)-one nucleoside (ABN), exhibits ?442=20,000 M?1 cm?1 and ?em,540=0.39 in water, increasing to ?em=0.50-0.53 when base paired with adenine in duplex DNA oligonucleotides. Single-molecule fluorescence measurements of ABN using both one-photon and two-photon excitation demonstrate its excellent photostability and indicate that the nucleoside is present to >95% in a bright state with count rates of at least 15 kHz per molecule.

Abstract: Fluorescent nucleobase surrogates capable of Watson-Crick hydrogen bonding are essential probes of nucleic acid structure and dynamics. Their limited brightness and short absorption and emission wavelengths have rendered them unsuitable for single-molecule detection. Herein, we synthesized a new tricyclic pyrimidine nucleoside analogue with a push-pull conjugated system. The resulting C-linked 8-(diethylamino)benzo[b][1,8] naphthyridin-2(1H)-one nucleoside (ABN), exhibits ?442=20,000 M?1 cm?1 and ?em,540=0.39 in water, increasing to ?em=0.50-0.53 when base paired with adenine in duplex DNA oligonucleotides. Single-molecule fluorescence measurements of ABN using both one-photon and two-photon excitation demonstrate its excellent photostability and indicate that the nucleoside is present to >95% in a bright state with count rates of at least 15 kHz per molecule.

Abstract: Fluorescent nucleobase surrogates capable of Watson-Crick hydrogen bonding are essential probes of nucleic acid structure and dynamics. Their limited brightness and short absorption and emission wavelengths have rendered them unsuitable for single-molecule detection. Herein, we synthesized a new tricyclic pyrimidine nucleoside analogue with a push-pull conjugated system. The resulting C-linked 8-(diethylamino)benzo[b][1,8] naphthyridin-2(1H)-one nucleoside (ABN), exhibits ?442=20,000 M?1 cm?1 and ?em,540=0.39 in water, increasing to ?em=0.50-0.53 when base paired with adenine in duplex DNA oligonucleotides. Single-molecule fluorescence measurements of ABN using both one-photon and two-photon excitation demonstrate its excellent photostability and indicate that the nucleoside is present to >95% in a bright state with count rates of at least 15 kHz per molecule.

Abstract: In a mounting system for an assembly in a high-frequency desktop device, a chassis element ("element") provides ground. For best ground, features formed in the element near a first edge of the assembly force the two together with no fastener there. Fasteners or other provisions secure the assembly, near its second edge, to the element. The features capture the first edge at installation; the fasteners etc. secure the assembly, near its second edge so that the features pinch the first. In another form of the system (1) first raised shapes formed in the element support the assembly near its first edge; (2) features, also formed in the element next to the first shapes, engage and capture the first edge; (3) second raised shapes, formed in the element, support the assembly near its second edge; and (4) fasteners etc. secure the assembly, near its second edge.