Surface coupling of oligo-functionalized dendrimers to detect DNA mutations after blocked isothermal amplification

Abstract

This study presents a useful strategy for the bioconjugation of probes for developing high-performance versatile chips applied to fast-response, low-cost DNA biosensing. We herein demonstrate that the high-density immobilization of dendrimer-oligonucleotide hybrids promotes the reliable sensitive sensing of single-nucleotide variants despite their low concentration.Carboxyl-terminated poly(amidoamine) dendrimers directly coupled to amine-derivatized oligonucleotides were anchored to the activated surfaces of thermoplastics (polycarbonate and cycloolefin polymer). Surface characterization techniques and hybridization assays reported that the multiple functional sites of the oligo-functionalized dendrimer facilitated the efficient immobilization of probes and the sensitive capture of DNA targets (5 pM detection limit). Array performance was better than that of the surfaces functionalized with linear crosslinkers, such as vinyltriethoxysilane or 3-(triethoxysilyl)propyl isocyanate, as well films with unconjugated dendrimer molecules.Based on oligo-dendrimers hybrids, disposable DNA-based biosensing platforms were developed for point-of-care diagnostics. A selective high-sensitive hybridization assay was performed that included amplification products of blocked PCR and recombinase polymerase amplification (RPA) as an isothermal reaction. The chip results indicated that the single-nucleotide mutant variant of the BRAF oncogene was correctly discriminated in colorectal tissues from cancer patients.