Robust and specific ratiometric biosensing using a copper-free clicked quantum dot-DNA aptamer sensor.
We report herein the successful preparation of a compact and functional CdSe-ZnS core-shell quantum dot (QD)-DNA conjugate via highly efficient copper-free "click chemistry" (CFCC) between a dihydro-lipoic acid-polyethylene glycol-azide (DHLA-PEG-N3) capped QD and a cyclooctyne modified DNA. This represents an excellent balance between the requirements of high sensitivity, robustness and specificity for the QD-FRET (Förster resonance energy transfer) based sensor as confirmed by a detailed FRET analysis on the QD-DNA conjugate, yielding a relatively short donor-acceptor distance of ~5.8 nm. We show that this CFCC clicked QD-DNA conjugate is not only able to retain the native fluorescence quantum yield (QY) of the parent DHLA-PEG-N3 capped QD, but also well-suited for robust and specific biosensing; it can directly quantitate, at the pM level, both labelled and unlabelled complementary DNA probes with a good SNP (single-nucleotide polymorphism) discrimination ability in complex media, e.g. 10% human serum via target-binding induced FRET changes between the QD donor and the dye acceptor. Furthermore, this sensor has also been successfully exploited for the detection, at the pM level, of a specific protein target (thrombin) via the encoded anti-thrombin aptamer sequence in the QD-DNA conjugate.
School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. y.guo@leeds.ac.uk d.zhou@leeds.ac.uk.
Haiyan
H
Zhang
Guoqiang
G
Feng
Yuan
Y
Guo
Dejian
D
Zhou
D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000378:metabolism; D001386:Azides / Q000737:chemistry; D015374:Biosensing Techniques; D057930:Click Chemistry; D003300:Copper / Q000737:chemistry*; D004247:DNA / Q000032:analysis* / Q000378:metabolism; D015342:DNA Probes / Q000737:chemistry / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D011092:Polyethylene Glycols / Q000737:chemistry; D020641:Polymorphism, Single Nucleotide; D011485:Protein Binding; D045663:Quantum Dots / Q000737:chemistry*; D008063:Thioctic Acid / Q000737:chemistry; D013917:Thrombin / Q000032:analysis / Q000378:metabolism
D052157:Aptamers, Nucleotide; D001386:Azides; D015342:DNA Probes; C081676:thrombin aptamer; D011092:Polyethylene Glycols; D008063:Thioctic Acid; D003300:Copper; D004247:DNA; D013917:Thrombin