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.

tosylate electrodes on plastic substrates enables new electrochemical measurements at this polymer using FSCV.

Bile salts are facially amphiphilic, naturally occurring chemicals that aggregate to perform numerous biochemical processes. Because of their unique intermolecular properties, bile salts have also been employed as functional materials in medicine and separation science (e.g., drug delivery, chiral solubilization, purification of single-walled carbon nanotubes). Bile micelle formation is structurally complex, and it remains a topic of considerable study. Here, the exposed functionalities on the surface of cholate and deoxycholate micelles are shown to vary from one another and with the micelle aggregation state. Collectively, data from NMR and capillary electrophoresis reveal preliminary, primary, and secondary stepwise aggregation of the salts of cholic (CA) and deoxycholic (DC) acid in basic conditions (pH 12, 298 K), and address how the surface availability of chirally selective binding sites is dependent on these sequential stages of aggregation. Prior work has demonstrated sequential CA aggregation (pH 12, 298 K) including a preliminary CMC at ca. 7 mM (no chiral selection), followed by a primary CMC at ca. 14 mM that allows chiral selection of binaphthyl enantiomers. In this work, DC is also shown to form stepwise preliminary and primary aggregates (ca. 3 mM DC and 9 mM DC, respectively, pH 12, 298 K) but the preliminary 3 mM DC aggregate is capable of chirally selective solubilization of the binaphthyl enantiomers. Higher-order, secondary bile aggregates of each of CA and DC show significantly degraded chiral selectivity. Diffusion NMR reveals that secondary micelles of CA exclude the BNDHP guests, while secondary micelles of DC accommodate guests, but with a loss of chiral selectivity. These data lead to the hypothesis that secondary aggregates of DC have an exposed binding site, possibly the 7α-edge of a bile dimeric unit, while secondary CA micelles do not present binding edges to the solution, potentially instead exposing the three alcohol groups on the hydrophilic α-face to the solution.

Previous work has demonstrated the utility of poly­(3,4-theylene­dioxy­thiophene) (PEDOT) electrodes for electrochemical detection of neurochemicals. Although these electrodes have been implemented successfully, there is minimal data linking redox mechanisms, electron-transfer characteristics, and sensor lifetime to the electrode molecular composition. Common polymer electrodes are made from commercially available PEDOT:polystyrenesulfonate (PEDOT:PSS), which is easily processed but has slow electron-transfer kinetics and short electrochemical lifetimes. Here, we describe vapor-phase synthesized PEDOT:tosylate films that have a higher conductance and a much lower apparent capacitance than PEDOT:PSS (99 ± 8 versus 2390 ± 130 μF/cm2). Additionally, we show that the electron-transfer kinetics and electrochemical lifetime are both improved. To investigate the chemical causes of these improvements we used ultraviolet–visible absorbance and X-ray photoelectron spectroscopy (XPS). We discovered that the high density of PEDOT incorporated into PEDOT:tosylate films coupled with the lack of impurities and replacing the polymeric dopant (PSS) leads to both increased conductance and reduced film capacitance. This is most clearly demonstrated through the doping ratio of 3.80 ± 0.10 in vapor-phase synthesized PEDOT:tosylate versus 0.20 ± 0.02 in PEDOT:PSS. Furthermore, the electrochemical lifetime of the films is dependent upon the amount of PEDOT present. XPS data was used to elucidate the mode of failure of these electrodes. This begins to illuminate the mechanism of electron transfer at conducting polymers electrodes. Understanding both the characteristics that improve the quality of conducting polymer electrodes and the mechanism of electron transfer therein is a crucial step in the wider adaptation of these materials in biosensor applications.