Aptamer-based electrochemical detection of picomolar platelet-derived growth factor directly in blood serum.
We report an electrochemical, aptamer-based (E-AB) sensor for the detection of platelet-derived growth factor (PDGF) directly in blood serum. The E-AB approach employs alternating current voltammetry to monitor target-induced folding in a methylene blue-modified, PDGF-binding aptamer. The sensor is sensitive, highly selective, and essentially reagentless: we readily detect the BB variant of PDGF at 1 nM directly in undiluted, unmodified blood serum and at 50 pM (1.25 ng/mL) in serum-diluted 2-fold with aqueous buffer. The sensitivity and selectivity achieved by this sensor match or significantly exceed those of the best analogous optical approaches. For example, the detection limit attained in 50% serum is achieved against a >25 million-fold excess of contaminating blood proteins and represents a 4 order of magnitude improvement over the most sensitive optical PDGF aptasensor reported to date. Moreover, the E-AB sensor combines these promising attributes in a platform that is reusable, label-free, and electronic. Given these advantages, E-AB sensors appear well suited for implementation in portable microdevices directed at the direct detection of proteins and small molecules in complex, largely unprocessed clinical samples.
Lai
Rebecca Y
RY
Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
Plaxco
Kevin W
KW
Heeger
Alan J
AJ
D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D001665:Binding Sites; D015374:Biosensing Techniques / Q000379:methods*; D001774:Blood Chemical Analysis; D004563:Electrochemistry; D006801:Humans; D007700:Kinetics; D008751:Methylene Blue / Q000737:chemistry; D009690:Nucleic Acid Conformation; D055095:Optics and Photonics; D010982:Platelet-Derived Growth Factor / Q000032:analysis*; D012680:Sensitivity and Specificity
D052157:Aptamers, Nucleotide; D010982:Platelet-Derived Growth Factor; D008751:Methylene Blue