Cationic Polyelectrolyte Amplified Bead Array for DNA Detection with Zeptomole Sensitivity and Single Nucleotide Polymorphism Selectivity

Abstract

A highly sensitive strand specifi c DNA assay, which consists of a peptide nucleic acid (PNA) probe, a cationic conjugated polymer ( PFVP ), and selfassembled polystyrene beads in microwell arrays on silicon chip, is reported. PFVP , as an effi cient signal amplifi er and signal reporter, has been specially designed and synthesized to be compatible with commercial confocal microscopes for sensing on solid substrates. The assay operates on the net increase in negative charge at the PNA surface that occurs upon singlestranded DNA hybridization, which subsequently allows complex formation with the positively charged PFVP to favor energy transfer between the polymer and Cy5-labeled target. With maximized surface contact provided by bead arrays and signal amplifi cation provided by PFVP , this assay allows detection of ∼ 300 copies of Cy5-labeled DNA using a commercial confocal microscope. In addition, the same strategy is also extended for label-free DNA detection with a detection sensitivity of 150 attomole. Excellent discrimination against single nucleotide polymorphism (SNP) is also demonstrated for both Cy5-labeled and label-free target detection. This study indicates that cationic conjugated polymers have great potential to be incorporated into the widely used microarray technology for simplifi ed process with improved detection sensitivity.

Conjugated polyelectrolytes for label-free visual detection of heparin

“…In particular, the large absorption cross-section and collective optical response of CPEs make them superior in the transduction of optical signals [10], ultimately giving rise to higher sensitivity with lower signal-to-noise ratio as compared to small-molecule fluorophores [11]. To date, CPEs have been successfully applied to detect a variety of biomolecules, including nucleic acid [12][13][14][15][16][17][18], peptide [19], protein [20][21][22][23][24][25][26], adenosine triphosphate [27], amines [28], folic acid [29] and glucose [30].…”

Conjugated-Polymer-Amplified Sensing, Imaging, and Therapy

“…41 In 2010, we reported a highly sensitive and selective CP-amplified bead array platform for DNA detection. 42 In this layout, PNA immobilized on the surface of bead arrays was chosen as the probe, and cationic CP P6 ( Figure 6A), which is compatible with commonly used commercial laser sources (e.g., 408 nm, 457 nm excitation, and 515/530 nm detector), was designed to serve as the energy donor. The preparation of the probe-immobilized bead array is schematically illustrated in Figure 6B.…”

Suspension arrays based on nanoparticle-encoded microspheres for high-throughput multiplexed detection

“…Liu et al 207 used a cationic conjugated polymer (CCP) poly(fluorenyldivinylene-alt1,4-phenylene) (PFVP) as either a signal amplifier (FRET pattern) or a signal reporter (label-free pattern) in a bead-based array for DNA detection (Fig. 23) with SNP selectivity.…”