title: Single quantum dot based nanosensor for renin assay.
abstract: Evaluation of plasma renin activity is essential to the assessment of renin-related diseases such as hypertension, congestive heart failure, and cancers. Here, we develop a single quantum dot (QD) based nanosensor for sensitive detection of renin activity. This single-QD-based nanosensor consists of a streptavidin-coated QD and multiple biotinylated and Cy5-labeled peptide substrates, which form a QD/substrate/Cy5 complex where fluorescence resonance energy transfer (FRET) occurs with the QD as the donor and Cy5 as the acceptor. The presence of renin leads to the cleavage of the substrate and the separation of Cy5 from the QD and consequently the decrease of FRET efficiency and the reduction of Cy5 counts. Through the measurement of Cy5 counts by total internal reflection fluorescence (TIRF) microscopy, the renin activity can be quantitatively evaluated at the single-molecule level. This single-QD-based nanosensor can measure not only the renin concentration, but also the enzymatic velocity and the Michaelis-Menten kinetic parameters, and has significant advantages of simplicity, low cost with minimum sample consumption, and high sensitivity with a detection limit of 25 pM. This single-QD-based nanosensor might be further applied to monitor a variety of important enzymatic biomarkers such as kinases and endonuleases.
authors.affiliation: Single-Molecule Detection and Imaging Laboratory, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Guangdong 518055, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Long
authors.forename: Ling-fei
authors.initials: LF
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chun-yang
authors.initials: CY
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D019921:Biotinylation; D002232:Carbocyanines / Q000032:analysis / Q000378:metabolism; D057075:Enzyme Assays / Q000379:methods*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000032:analysis / Q000378:metabolism; D057230:Limit of Detection; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D059748:Proteolysis; D045663:Quantum Dots; D012083:Renin / Q000097:blood / Q000378:metabolism*; D019809:Streptavidin / Q000737:chemistry
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D010455:Peptides; C085321:cyanine dye 5; D019809:Streptavidin; D012083:Renin