Figure 7.

MFA allows selective multiplex detection of nucleic acids (a–f), antibodies (g–k), or both nucleic acids and antibodies simultaneously (l). In panels (a)–(e), six different DNA capture probe sequences on six different optical codes, one of which is a universal negative control (S₃), are present in all reactions set up as a lateral flow experiment (Figure 2a–f). Five dye-labeled targets (∼10 nM), each of which is complementary to one of the five bead-bound capture probes (a–e), are added one at a time to the six bead codes present in each of the five assays (a–e). Each target rapidly binds to its complementary capture probe with high selectivity (Figure 5) and all noncomplementary capture probes display low backgrounds without washing (a–e). When all five labeled targets are added, all beads except the negative control bind their respective targets (f). Ab analytes may be detected in a multiplexed fashion as shown in Figure 1c. The Abs against the bead-bound recombinant protein antigens troponin I (g), HBV (h), HCV (i), and Inf A (j) are added in a flow-through geometry (Figure 2h) to the five bead-bound recombinant protein capture probes one at a time (g–j) or all (troponin I, HBV, HCV, HIV, and Inf A) at once (k) and subsequently stained with dye-labeled rabbit anti-mouse (troponin I, HBV, HCV, and Inf A) or labeled rabbit anti-human (HIV). It is also possible to detect simultaneously four DNA sequences, three Abs, and a negative control within the same assay (l). The number of beads measured for each analyte is given at the lower right of each bar.