Temporally-resolved quantification of physiological analytes is important for understanding cellular signaling pathways. However, many important signaling molecules (e.g. glucose and inositol phosphates) are difficult to directly monitor in living cells. The use of radiolabels, particularly tritium (3H), is advantageous because it provides minimal perturbation to the structure, mass, and binding characteristics of the parent compound. 3H-labeled compounds can be detected through scintillation, a process that transduces low-energy beta particles emitted during radioactive decay into photons in the visible range of the electromagnetic spectrum. Traditional scintillation counting uses liquid scintillation cocktails composed of aromatic hydrocarbons and dyes to perform this energy conversion, making the technique incompatible with monitoring living cells. To circumvent this problem, we have developed multifunctional nanoparticles for scintillation proximity assay (nanoSPA). nanoSPA detects radiolabeled analytes in close proximity to the nanoparticle, allowing for analyte-selective optical signals. nanoSPA showed enhanced response in two different binding model systems: NeutrAvidin-biotin binding and ds-DNA hybridization. Biotinylated nanoparticles showed enhanced scintillation response towards 3H-NeutrAvidin versus non-binding conditions. ssDNA-functionalized nanoparticles were found to respond towards 3H-labeled complementary and non-complementary mismatch ssDNA. nanoSPA was then extended to develop a sensor for 3H-glucose, an important analyte in cellular signaling of diseases such as diabetes. nanoSPA functionalized with glucose-binding moieties showed enhanced response towards 3H-glucose with physiologically-relevant concentrations as compared to non-binding effects.

Radioisotope-responsive polystyrene-silica core-shell nanoparticles used in scintillation proximity assay for tritium

251st National Meeting (2016)

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