2 research outputs found
Nonlinear Photoluminescence Spectroscopy of Carbon Nanotubes with Localized Exciton States
We report distinctive nonlinear behavior of photoluminescence (PL) intensities from localized exciton states embedded in single-walled carbon nanotubes (SWNTs) at room temperature. We found that PL from the local states exhibits strong nonlinear behavior with increasing continuous-wave excitation power density, whereas free exciton PL shows only weak sublinear behavior. The strong nonlinear behavior was observed regardless of the origin of the local states and found to be nearly independent of the local state density. These results indicate that the strong PL nonlinearity arises from a universal mechanism to SWNTs with sparse local states. The significant nonlinear PL is attributed to rapid ground-state depletion of the local states caused by an efficient accumulation of photogenerated free excitons into the sparse local states through one-dimensional diffusional migration of excitons along the nanotube axis; this mechanism is verified by Monte Carlo simulations of exciton diffusion dynamics
Multiplexed Targeting of Barrett’s Neoplasia with a Heterobivalent Ligand: Imaging Study on Mouse Xenograft in Vivo and Human Specimens ex Vivo
Esophageal adenocarcinoma (EAC) is
a molecularly heterogeneous
disease that is rising rapidly in incidence and has poor prognosis.
We developed a heterobivalent peptide to target detection of early
Barrett’s neoplasia by combining monomer heptapeptides specific
for either EGFR or ErbB2 in a heterodimer configuration. The structure
of a triethylene glycol linker was optimized to maximize binding interactions
to the surface receptors on cells. The Cy5.5-labeled heterodimer QRH*–KSP*–E3–Cy5.5
demonstrated specific binding to each target and showed 3-fold greater
fluorescence intensity and 2-fold higher affinity compared with those
of either monomer alone. Peak uptake in xenograft tumors was observed
at 2 h postinjection with systemic clearance by ∼24 h in vivo.
Furthermore, ligand binding was evaluated on human esophageal specimens
ex vivo, and 88% sensitivity and 87% specificity were found for the
detection of either high-grade dysplasia (HGD) or EAC. This peptide
heterodimer shows promise for targeted detection of early Barrett’s
neoplasia in clinical study