Colorimetric detection of clinical DNA samples using an intercalator-conjugated polydiacetylene sensor

•A novel colorimetric PDA sensor based on the intercalation was developed to detect dsDNA.•The PDA sensor detected clinical DNA as low as 20 nM and as small as around 100 base pairs.•Colorimetric change of the PDA sensor was observed in 1 h.•Due to its technical simplicity, rapidity, and high selectivity, this PDA sensor has potential clinical applications in POCT.

We herein developed a novel colorimetric polydiacetylene (PDA) sensor for very convenient detection of clinical DNA samples based on the interaction between an intercalator and dsDNA. We modified the terminal carboxyl group of a diacetylene monomer (10,12-pentacosadiynoic acid; PCDA) with the intercalator 9-aminoacridine (9AA) and prepared 9AA-modified PDA liposomes containing PCDA-9AA/PCDA/phospholipid (1,2-dimyristoyl-rac-glycero-3-phosphocholine) at a molar ratio of 1.5:6.5:2.0. The PDA sensor underwent an obvious color transition from blue to red in the presence of dsDNA molecules that were PCR-amplified from genomic DNA due to the insertion of the 9AA head group of PDA into the dsDNA. DNA concentrations as low as 20 nM and relatively small molecules (around 100 base pairs) could be detected by the sensor within 1 h without DNA electrophoresis. This novel colorimetric method is simple, does not require any instrument, and is therefore appropriate for POCT or portable molecular diagnostic kit.

Graphical abstractA 9-aminoacridine (9AA) intercalator-modified polydiacetylene (PDA) chromatic sensor containing diacetylene monomer and phospholipid is developed to detect dsDNA amplified from genomic DNA, which is visualized by a distinct color change caused by the insertion of the 9AA head group of PDA into dsDNA. The limits of detection of this method are 20 nM and sizes of around 100 base pairs.Figure optionsDownload full-size imageDownload as PowerPoint slide