A reusable optical biosensor for the ultrasensitive and selective detection of unamplified human genomic DNA with gold nanostars.
A Surface Plasmon Resonance imaging (SPRi) based DNA sensors for the selective and ultrasensitive human genomic DNA detection, directly extracted from lymphocytes (bypassing PCR amplification), is reported. To achieve DNA detection, a rationally chosen star-shaped nanoparticle (NP), namely gold nanostar (AuNS), has been applied, for the first time, in a sandwich-like assay based on the selective capturing of specific DNA targets and the subsequent signal amplification by a secondary DNA probe linked to AuNS. The plasmonic profile, size and electric field enhancements at the star tips contributed to the maximization of plasmon coupling between LSPs and SPs as aimed for analytical signal magnification. The system was first tested using short synthetic DNA target sequences and applied to DNA biosensing, lowering 610-fold the detection limit from 6.1 nM (without NSs labeling) to 10 pM (with NSs labeling). Then the biosensor was applied to genomic DNA samples, extracted from human lymphocytes and undergoing only to a simple ultrasonic fragmentation, lowering (~435 fold) the detection limit from 3.0 fM (without NSs labeling) to 6.9 aM (with NSs labeling). Thanks to the assay optimization, we proved that tuning the NSs surface coverage with DNA linked to nanoparticles is crucial not only for the increase of signals but also for the regenerability/reusability of the biosensor for tens of measurement cycles.
Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Via della Lastruccia 3-13, 50019 Sesto Fiorentino (FI), Italy.
Stefano
S
Mariani
Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Via della Lastruccia 3-13, 50019 Sesto Fiorentino (FI), Italy.
Simona
S
Scarano
Laboratoire de Réactivité de Surfaces, UMR CNRS 7197, Université Pierre & Marie Curie - Paris VI, Site d'Ivry - Le Raphae¨l, 94200 Ivry-sur-Seine, France; Laboratoire CSPBAT UMR7244, UFR Santé, Médecine et Biologie Humaine, Université Paris 13, 74 rue Marcel Cachin, 93017 Bobigny, France.
Jolanda
J
Spadavecchia
Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Via della Lastruccia 3-13, 50019 Sesto Fiorentino (FI), Italy. Electronic address: maria.minunni@unifi.it.
Maria
M
Minunni
D001483:Base Sequence; D015374:Biosensing Techniques / Q000295:instrumentation*; D002874:Chromosome Mapping / Q000295:instrumentation*; D004247:DNA / Q000032:analysis / Q000235:genetics*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017743:Equipment Reuse; D015894:Genome, Human / Q000235:genetics; D006046:Gold / Q000737:chemistry; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D021141:Nucleic Acid Amplification Techniques; D055096:Optical Devices; D017422:Sequence Analysis, DNA / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
D006046:Gold; D004247:DNA
Gold nanoparticles (AuNPs); Gold nanostars (AuNSs); Reusable biosensor; Surface Plasmon Resonance imaging (SPRi); Unamplified genomic DNA detection