Dynamic measurements of [IP3]i in cardiac differentiated P19 (CD‐P19) cells with a novel quantum dots (QD) and gold nanoparticles (AuNP) nanobiosensor, QD‐IP3‐AuNP. (1097.4)

We reported the first measurements of the [IP3]i in intact CD‐P19 cells with a novel nanobiosensor for IP3, QD‐IP3‐AuNP. QD‐IP3‐AuNP was fabricated with QD580 (donor) and AuNP (acceptor); an IP3 receptor peptide (RP) was conjugated between them. QD fluorescence increases proportionally to [IP3] bound to the RP. Fluorescence microscope measurements (Ex=488; Em=535 and 580) were made in CD‐P19 cells loaded with (i) QD‐IP3‐AuNP, (ii) Fluo‐3, and (iii) both QD‐IP3‐AuNP and Fluo‐3. Differentiation of P19 cells was induced with 1% DMSO. The responses of [IP3]i and [Ca2+]i were interrogated with two agonists, McN343 (M1) and UTP (P2Y2); and three antagonists, pirenzipine(M1), suramine (P2), and thapsigargin (Ca‐ATPase). In each sample (n=5), cumulative doses (µM) of 0, 0.1, 1, 10, of either agonist were added, following with the applications of 10 µM of one of the antagonists and the repeated cumulative doses of the respective agonist, all at 6 min apart. The dose dependent increases of [IP3]i and [Ca2+]i by both agonists were inhibited by their respective receptor antagonists. For both agonists, thapsigargin had no effect on the induced increases of [IP3]i but further the induced increases in [Ca2+]i. These data suggest that [IP3]i measurements with QD‐IP3‐AuNP in CD‐P19 cells could be a robust platform for cardiac drug discovery and toxicology.