Multianalyte, dipstick-type, nanoparticle-based DNA biosensor for visual genotyping of single-nucleotide polymorphisms.
DNA biosensors involve molecular recognition of the target sequence by hybridization with specific probes and detection by electrochemical, optical or gravimetric transduction. Disposable, dipstick-type biosensors have been developed recently, which enable visual detection of DNA without using instruments. In this context, we report a multianalyte DNA biosensor for visual genotyping of two single-nucleotide polymorphisms (SNPs). As a model, the biosensor was applied to the simultaneous genotyping of two SNPs, entailing the detection of four alleles. A PCR product that flanks both polymorphic sites is subjected to a single primer extension (PEXT) reaction employing four allele-specific primers, each containing a region complementary to an allele and a characteristic segment that enables subsequent capture on a test zone of the biosensor. The primers are extended with dNTPs and biotin-dUTP only if there is perfect complementarity with the interrogated sequence. The PEXT mixture is applied to the biosensor. As the developing buffer migrates along the strip, all the allele-specific primers are captured by immobilized oligonucleotides at the four test zones of the biosensor and detected by antibiotin-functionalized gold nanoparticles. As a result, the test zones are colored red if extension has occurred denoting the presence of the corresponding allele in the original sample. The excess nanoparticles are captured by immobilized biotinylated albumin at the control zone of the sensor forming another red zone that indicates the proper performance of the system. The assay was applied successfully to the genotyping of twenty clinical samples for two common SNPs of MBL2 gene.
Department of Chemistry, University of Athens, Athens 15771, Greece.
Ioannis K
IK
Litos
Penelope C
PC
Ioannou
Theodore K
TK
Christopoulos
Jan
J
Traeger-Synodinos
Emmanuel
E
Kanavakis
D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D004247:DNA / Q000032:analysis* / Q000235:genetics*; D017931:DNA Primers; D005838:Genotype; D006046:Gold; D006801:Humans; D037601:Mannose-Binding Lectin / Q000235:genetics; D053768:Metal Nanoparticles; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D015203:Reproducibility of Results
D017931:DNA Primers; C445619:MBL2 protein, human; D037601:Mannose-Binding Lectin; D006046:Gold; D004247:DNA