Label‐Free and Self‐Signal Amplifying Molecular DNA Sensors Based on Bioconjugated Polyelectrolytes

Abstract

Hybrid bio/‐synthetic sensory conjugated polyelectrolytes were developed to achieve selective label‐free detection of target oligonucleotides with amplified fluorescence signal in solution. A completely water soluble and highly fluorescent conjugated poly(p‐phenyleneethynylene) (PPE) was rationally designed and synthesized as a signal amplifying unit and chemically modified with carboxylic functional groups at the ends of the polymer chains to bioconjugate with amine functionalized single‐stranded oligonucleotides as a receptor using carbodiimide chemistry. This approach allows the functional groups on the polymers to be effectively linked to DNA without any damage to the conjugated π‐system of the polymers. DNA detection results using the PPE‐DNA hybrid system confirmed large signal amplification by means of efficient Förster energy transfer from the energy harvesting PPE to the fluorescent dye attached to the complementary analyte DNA. To realize label‐free detection, we also connected a DNA molecular beacon to the newly developed conjugated polymer as a self‐signaling molecular switch. A DNA detection study by using the resulting PPE‐DNA beacon and single strand analyte DNAs showed not only signal‐amplification properties but also self‐signaling properties.

DNA Block Copolymers: Functional Materials for Nanoscience and Biomedicine

“…In the first approach, carboxylic acid terminated polymers were coupled to amino-functionalized ODNs forming an amide bond. 16,17 A second strategy for solution-based conjugation of a hydrophilic polymer like poly(ethylene glycol) (PEG) to an oligonucleotide relied on disulfide bond formation between thiol-modified polymer and ODN. 18 Besides the formation of amide and disulfide bonds, the Michael addition was one of the common approaches for the attachment of ODNs to hydrophilic polymers.…”

Sensitive fluorescent sensing for DNA assay

“…Lee et al developed a biosynthetic anionic poly(phenyleneethynylene) (PPE)-DNA sensor for efficient self-signal-amplifying DNA detection in aqueous solution (Fig. 2) [60]. By using a simple carboiimide chemistry, PPE was successfully conjugated to DNA molecules by amide-bond formation.…”

“…One-step or two-step fluorescent resonance-energy transfer (FRET) process to detect DNA using conjugated polyelectrolytes (CPs) Figure 2. Polymer-oligonucleotide bioconjugation to form poly (p-phenylene ethynylene) with DNA (PPE-DNA) (top) to demonstrate signal amplifying property by fluorescence resonance energy transfer (FRET) and PPE-DNA beacon (bottom) to demonstrate self-signal amplifying label-free detection [60]. Figure 1.…”

Study of the Interaction between a Water-Soluble Cationic Poly(heteroarylene methine) and DNA

“…Water soluble conjugated polymers have been prepared by the introduction of ionic moieties as pendant groups to the polymer backbone since the conjugated backbone itself can behave as a fluorophore [15]. Water soluble cationic conjugated polymers have been demonstrated to be useful for DNA detection and quantification by the electrostatic interactions with the negatively charged phosphate groups of DNA [16]. Studies of DNA detection using cationic conjugated polymers, for example, poly(phenylenevinylene) derivatives [17] or polythiophene derivatives [18], previously reported.…”