Charge-tagged nucleotides and methods of use thereof

A method comprising:

• detecting an incorporation of a labelled nucleotide into a nascent polynucleotide strand complementary to a template polynucleotide strand by a polymerase, wherein the polymerase is tethered to a solid support conductive channel by a tether,
• the labelled nucleotide is a compound of Formula I
• wherein n is an integer from 3 to 10,
• m is an integer from 1 to 10,
• t is an integer from 0 to 50,
• X1 is a direct bond, a C1-C10 alkyl, a C1-C10 oxaalkyl, a C1-C10 thiaalkyl, or a C1-C10 azaalkyl,
• X2 is C1-C20 alkyl wherein optionally one or more individual CH2 residue is replaced with one or more of a peptide bond and (—O—CH2—CH2-)a wherein a is an integer from 1 to 24,
• X3 is a direct bond or an oligonucleotide wherein the oligonucleotide hybridizes to an acceptor region of the tether when the label is in proximity to the conductive channel,
• F1 is selected from a fluorophore and a direct bond and F2 is absent or a fluorophore,
• A is
• or an amide bond, and
• Y is selected from
• q is 1, and
• B comprises a dendron of z generations comprising one or more constitutional repeating unit and a plurality of end units, wherein z is an integer from 1 to 6, the constitutional end units are selected from:
• wherein
• p1 is an integer from 1 to 3, wherein any one or more of the p1 —CH2— groups is optionally replaced with from 1 to 3 —O—CH2—CH2— groups,
• p2 is an integer from 1 to 3, wherein any one or more of the p2 —CH2— groups is optionally replaced with from 1 to 3 —O—CH2—CH2— groups, and
• the end units are selected from carboxylic acid, sulfonic acid, phosphonic acid, sperminyl group, amino group, and quaternary ammonium group, and B has a charge and a charge density, and
• the charge sensor is to detect the labelled nucleotide during the incorporation.