Development of polydiacetylene (PDA) biosensors for detection of nucleic acids and GST-fusion recombinant protein

Abstract

Polydiacetylene (PDA)-based biosensors for the detection of biologically important molecules such as protein, DNA, enzyme, and so on have been intensively investigated due to the unique stimuli-responsive color-changing properties as well as fluorescence properties. The purpose of this study is development of a diagnostic technique with potentiality of point-of-care device. PDA biosensors can be applied to detect various biomolecules containing proteins, virus, bacteria, lipophilic enzymes, antibacterial peptide, soluble ions, drugs, pharmacologically active compounds, and so on. In this study, we describe PDA liposome as a colorimetric biosensor to detect streptavidin (STA), nucleic acid, and GST-fusion recombinant protein and PDA chip as a fluorescence biosensor to detect nucleic acid based on the ligand-receptor interaction. The natural binding of STA for a small vitamin, biotin, has made it a useful tool in specific targeting application, due to their most specific noncovalent biological interactions in nature. Their bond formation is rapid and non-reversible. Here, we modified terminal group of diacetylene monomer with biotin having different spacers to impart a functionality of specific recognition. Prepared biotin-modified PDA liposomes using them showed a color change from blue to red in about 1 hr, upon the addition of STA. For the selective detection of nucleic acids using a PDA colorimetric sensor, we developed a novel colorimetric detecting method of the polymerase chain reaction (PCR)-amplified nucleic acids based on ionic interaction. In order to induce color change by the ionic interaction between the positively charged PDA and negatively charged phosphate backbone of the nucleic acids, terminal group of diacetylene monomer was modified with positive charged amine groups. The resulting PDA sensors containing functional amine-modified diacetylene monomer showed a dramatic color change from blue to red immediately after the addition of nucleic ...