No abstract

The relatively simple and robust architecture of microelectronic devices based on carbon nanotubes, in conjunction with their environmental sensitivity, places them among the leading candidates for incorporation into ultraportable or wearable chemical analysis platforms. We used single-walled carbon nanotube (SWNT) networks to establish a mechanistic understanding of the solid-state oxygen sensitivity of a Eu(3+)-containing dendrimer complex. After illumination with 365 nm light, the SWNT networks decorated with the Eu(3+) dendrimer show bimodal (optical spectroscopic and electrical conductance) sensitivity towards oxygen gas at room temperature under ambient pressure. We investigated the mechanism of this unique oxygen sensitivity with time-resolved and steady-state optical spectroscopy, analysis of excited-state luminescence lifetimes and solid-state electrical transport measurements. We demonstrate a potential application of this system by showing a reversible and linear electrical response to oxygen gas in the tested range (5-27%).

We report four supermolecular chromophores based on (porphinato)zinc(II) (PZn) and (polypyridyl)metal units bridged via ethyne connectivity (Pyr1RuPZn2, Pyr1RuPZnRuPyr1, Pyr1RuPZn2RuPyr1, and OsPZn2Os) that fulfill critical sensitizer requirements for NIR-to-vis triplet-triplet annihilation upconversion (TTA-UC) photochemistry. These NIR sensitizers feature: (i) broad, high oscillator strength NIR absorptivity (700 nm < λ(max(NIR)) < 770 nm; 6 × 10(4) M(-1) cm(-1) < extinction coefficient (λ(max(NIR))) < 1.6 × 10(5) M(-1) cm(-1); 820 cm(-1) < fwhm < 1700 cm(-1)); (ii) substantial intersystem crossing quantum yields; (iii) long, microsecond time scale T1 state lifetimes; and (iv) triplet states that are energetically poised for exergonic energy transfer to the molecular annihilator (rubrene). Using low-power noncoherent illumination at power densities (1-10 mW cm(-2)) similar to that of terrestrial solar photon illumination conditions, we demonstrate that Pyr1RuPZn2, Pyr1RuPZn2RuPyr1, and Pyr1RuPZnRuPyr1 sensitizers can be used in combination with the rubrene acceptor/annihilator to achieve TTA-UC: these studies represent the first examples whereby a low-power noncoherent NIR light source drives NIR-to-visible upconverted fluorescence centered in a spectral window within the bandgap of amorphous silicon.

We have created a dendrimer complex suitable for preferential accumulation within liver tumors and luminescence imaging by substituting thirty-two naphthalimide fluorophores on the surface of the dendrimer and incorporating eight europium cations within the branches. We demonstrate the utility and performance of this luminescent dendrimer complex to detect hepatic tumors generated via direct subcapsular implantation or via splenic injections of colorectal cancer cells (CC531) into WAG/RijHsd rats. Luminescence imaging of the tumors after injection of the dendrimer complex via hepatic arterial infusion revealed that the dendrimer complex can preferentially accumulate within liver tumors. Further investigation indicated that dendrimer luminescence in hepatic tumors persisted in vivo. Due to the incorporation of lanthanide cations, this luminescence agent presents a strong resistance against photobleaching. These studies show the dendrimer complex has great potential to serve as an innovative accumulation and imaging agent for the detection of metastatic tumors in our rat hepatic model.

Surgery is currently the best approach for treating either primary or metastatic hepatic malignancies. Since only 20% of patients with hepatic cancer are operable, regional therapies (RT) are emerging as alternate treatment modalities. However, RT's can have their own limitations at controlling tumor growth or lack the ability to detect such metastases. More can be done to enhance their efficacy. An animal model of hepatic metastases coupled with a gastroduodenal artery (GDA) cannulation technique may provide a site to apply such therapies. In our study, splenic injections were performed with CC531 adenocarcinoma cells, which generated metastatic hepatic tumors in WAG/RijHsd rats. Cannulation of GDA was achieved via a polyethylene catheter. Infusion of generation 3 polyamidoamine 4-amino-1,8-naphthalimide containing 8 europium ions (Eu-G3P4A18N) dendrimer via the GDA resulted in luminescence of the hepatic metastatic nodules. Imaging of the metastatic hepatic nodules was obtained with the help of a digital charge coupled device camera.