An aptamer-based bio-barcode assay with isothermal recombinase polymerase amplification for cytochrome-c detection and anti-cancer drug screening

• Published in: Talanta (Oxford) 2013-10, Vol.115, p.159-165
• Main Authors: Loo, Jacky, Lau, P.M., Ho, H.P., Kong, S.K.
• Format: Article
• Language: English
• Subjects: Anti-cancer drug screening; antibodies; Antibodies - chemistry; antigens; Antigens, Neoplasm - chemistry; antineoplastic agents; Antineoplastic Agents - pharmacology; Aptamer; Aptamers, Nucleotide - chemistry; barcoding; binding capacity; Bio-barcode assay; cell death; Cell Death - drug effects; Cell Line, Tumor; chemical bonding; chemical species; cytochrome c; Cytochromes c - analysis; Cytochromes c - genetics; detection limit; DNA libraries; Drug Screening Assays, Antitumor - methods; fluorescence; Fluorescent Dyes; Gold - chemistry; heat; Humans; Limit of Detection; liver neoplasms; magnetic fields; Magnets; Metal Nanoparticles - chemistry; Molecular Typing - methods; multiple drug resistance; nanogold; Nucleic Acid Amplification Techniques; nucleotide sequences; oligonucleotides; PCR; polymerase chain reaction; Polyphyllin D; recombinase polymerase amplification; Recombinases - chemistry; Recombinases - genetics; screening; single-stranded DNA
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2013.04.051

Based on a recently reported ultra-sensitive bio-barcode (BBC) assay, we have developed an aptamer-based bio-barcode (ABC) alternative to detect a cell death marker cytochrome-c (Cyto-c) and its subsequent application to screen anti-cancer drugs. Aptamer is a short single-stranded DNA selected from a synthetic DNA library by virtue of its high binding affinity and specificity to its target based on its unique 3D structure from the nucleotide sequence after folding. In the BBC assay, an antigen (Ag) in analytes is captured by a micro-magnetic particle (MMP) coated with capturing antibodies (Abs). Gold nanoparticles (NPs) with another recognition Ab against the same target and hundreds of identical DNA molecules of known sequence are subsequently added to allow the formation of sandwich structures ([MMP-Ab1]-Ag-[Ab2-NP-DNA]). After isolating the sandwiches by a magnetic field, the DNAs hybridized to their complementary DNAs covalently bound on the NPs are released from the sandwiches after heating. Acting as an Ag identification tag, these bio-barcode DNAs with known DNA sequence are then amplified by polymerase chain reaction (PCR) and detected by fluorescence. In our ABC assay, we employed a Cyto-c-specific aptamer to substitute both the recognition Ab and barcode DNAs on the NPs in the BBC assay; and a novel isothermal recombinase polymerase amplification for the time-consuming PCR. The detection limit of our ABC assay for the Cyto-c was found to be 10ng/mL and this new assay can be completed within 3h. Several potential anti-cancer drugs have been tested in vitro for their efficacy to kill liver cancer with or without multi-drug resistance. •An aptamer bio-barcode (ABC) assay is developed to screen anti-cancer drugs.•An aptamer against cytochrome-c, a cell death marker, is used for drug screening.•The aptamer is used for both target recognition and barcode DNA amplification.•The barcode signal is magnified at 37°C by recombinase polymerase amplification.•Detection limit ~10ng/mL; completed within 3h.