A universal colorimetric method for the detection of nucleic acids, based on ionic interactions by polydiacetylene (PDA) liposomes, is described. Primary and quaternary amine‐modified diacetylene monomers were synthesized and used to generate positively charged PDA liposomes. The resulting PDA sensors showed a dramatic color change from blue to red upon the addition of nucleic acids amplified by using the polymerase chain reaction (PCR) due to the stimuli caused by ionic interactions between the positively charged PDA and negatively charged phosphate backbone of the nucleic acids. The color change that takes place can be simply detected by the naked eye. Compared with quaternary amine‐functionalized PDA vesicles, the primary amine‐functionalized PDA underwent a more intense color transition under optimized conditions. By using the PDA‐based colorimetric sensor, nucleic acids amplified by common PCR reaction, whose typical concentration is around 100 nM, can be readily detected. Since implementation of this universal colorimetric method is simple, rapid and does not require any sophisticated instrumentation, it should have greatly enhanced applications as a technology for DNA diagnosis.
A micropatterned polydiacetylene (PDA) chip, utilizing the unique fluorogenic property of PDA and a specific biotin-streptavidin (STA) interaction, is constructed to detect pathogen infections. To construct the PDA chip, biotin-modified diacetylene liposomes are immobilized on aldehyde glass and conjugated with STA, followed by UV irradiation to polymerize the STA-functionalized diacetylene liposomes. Genomic DNA of a model pathogen, Chlamydia trachomatis, is isolated from human samples and biotin-labeled target DNA is obtained through PCR amplification using biotin-11-dUTP. Owing to the stimulus caused by the biotin-STA interaction, the biotinylated DNA induces an intense fluorescence signal on the immobilized PDA. By using this strategy, it is possible to diagnose Chlamydia infections by applying DNA samples from several nonhealthy humans to a single PDA chip. The results of this study serve as the basis for a new strategy for fluorogenic PDA microarray-based diagnosis of pathogen infections.
A thermally actuated organic display device using UV-sensitive polydiacetylene (PDA)-polyvinyl alcohol (PVA) composite film with self aligned patterns is presented. A novel technique that patterns UV-sensitive organic films on a transparent substrate using a chip-embedded photomask is demonstrated. In contrast to related works regarding PDA and its composites, the current investigation represents the first attempt to realize a PDA derivative film for a thermal-display. Micro-pixels ranging from 200µm to 700µm size were fabricated on a glass substrate. The transition tones of the blue, red and yellow micro-pixels were successfully tuned with embedded micro-heaters under the PDA-PVA layer using both low-temperature (75°C) and high-temperature (180°C) activation processes. The retention time was measured and found to be less than a few hundred milliseconds.
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