Search

A new cationic poly(3,4-ethylenedioxythiophene)-DNA composite (P(EDOT-N)-DNA) has been prepared by in situ chemical oxidative polymerization of EDOT-N monomer in the presence of salmon DNA as template. Scanning electron microscopy shows that the P(EDOT-N)-DNA composite forms a porous pattern with a high surface area that is favorable for ion diffusion throughout the materials, which leads to improved capacitive activity. The P(EDOT-N)-DNA composite exhibits superior capacitance behavior as well as good charge-discharge reversibility. The P(EDOT-N)-DNA composite shows low cytotoxicity to living cells even at a concentration of 300 mg · L(-1) . The good biocompatibility of P(EDOT-N)-DNA imparts good potential as an environmentally friendly electrode material for energy storage devices, even in a biological environment owing to the combination of DNA with conjugated polymers.

A fluorescent turn-on detection for nitric oxide in aqueous solution is developed using cationic conjugated polymers. The assay benefits from the sensitivity of optical signals from conjugated polymers and the simplicity of fluorescence measurement techniques. The assay contains three elements: a cationic conjugated polymer that contains imidazole moieties, Cu 2+ ions, and the target nitric oxide. The highly fluorescent conjugated polymer coordinates to Cu 2+ ions through weak N . . . Cu interactions, and its fluorescence is efficiently quenched by a photoinduced electron transfer process ('off' state). In the presence of nitric oxide, the transformation of the paramagnetic Cu 2+ ion into a diamagnetic Cu 1+ ion inhibits the quenching and, therefore, the fluorescence of the conjugate polymer is recovered ('on' state). Other biologically relevant reactive nitrogen species, such as NOBF 4 , NaNO 2 , and NaNO 3 don't exhibit the fluorescence recovery of the conjugated polymer under the same conditions as nitric oxide. The cationic conjugated polymer/Cu 2+ complex can thus be used as a platform to detect nitric oxide in aqueous solution with high sensitivity and selectivity.

The CO2 -responsive and biocatalytic assembly based on conjugated polymers has been demonstrated by combining the signal amplification property of the polythiophene derivative (PTP) and the catalytic actions of carbonic anhydrase (CA). CO2 is applied as a new trigger mode to construct the smart assembly by controlling the electrostatic and hydrophobic interactions between the PTP molecules in aqueous solution, leading to the visible fluorescence changes. Importantly, the assembly transformation of PTP can be specifically and highly accelerated by CA based on the efficient catalytic activity of CA for the inter-conversion between CO2 and HCO3- , mimicking the CO2 -associated biological processes that occurred naturally in living organisms. Moreover, the PTP-based assembly can be applied for biomimetic CO2 sequestration with fluorescence monitoring in the presence of CA and calcium.