Conjugated Polymers and Polyelectrolytes for Electronic Devices and Fluorescence Assays
Abstract:
Conjugated polyelectrolytes (CPEs) have emerged as attractive and versatile optical platforms for highly sensitive chemo- or biosensors that can detect a variety of targets, including metal ions, DNA, RNA and peptides. CPEs are described by a p-conjugated backbone with ionic pendant groups, which make them water-soluble and/or bio-compatible. We report a new chemical- and/or bioassay using a molecular beacon aptamer (MBA) as a molecular recognition element and CPEs as an optical platform. The hairpin-type MBA labeled with a fluorophore and quencher at both termini undergoes a conformational change (by complexation with CPEs) to either an open-chain form or a G-quadruplex in the absence or presence of target. Conformational changes of MBA as well as signal quenching or amplification via fluorescence resonance energy transfer (FRET) from CPEs provide clear signal trun-off and –on in the presence or absence of target. Combination of high binding specificity of biosystems and synthetic CPEs with tunable optical amplification property provided the ultimate detection sensitivity and selectivity. A new strategy to extend the detection range of weakly-binding targets is also presented that takes advantage of FRET-based bioassays based on MBAs and CPEs.
Over the past few decades, polymer solar cells (PSCs) have made a significant progress, showing their potential in low-cost, flexible, lightweight, portable and large-area energy-harvesting devices. Considerable efforts have been dedicated toward the design of new materials, device architectures and processing techniques in order to improve the power conversion efficiency (PCE). To further improve the PCE value, first and foremost, the molecular structure of low bandgap (LBG) polymers should be carefully designed by considering its close relationship with the photovoltaic parameters, including short-circuit current density (JSC), open-circuitvoltage (VOC) and fill factor (FF). Here, we present a series of crystalline low bandgap polymers which were designed by considering the backbone planarity, noncovalent intra- and interchain interactions (via H-bonding and dipole-dipole interactions, etc) and solution processibility, leading to highly ordered film morphologies and PCEs approaching ~10%. The molecular design and resulting morphological, electrical and device properties will be discussed in detail.