Base amount-dependent fluorescence enhancement for the assay of vascular endothelial growth factor 165 in human serum us
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ORIGINAL PAPER
Base amount-dependent fluorescence enhancement for the assay of vascular endothelial growth factor 165 in human serum using hairpin DNA-silver nanoclusters and oxidized carbon nanoparticles Jiangrong Ji 1 & Xin Xu 1 & Panpan Chen 1 & Jiafeng Wu 1 & Yang Jin 1 & Liying Zhang 1 & Shuhu Du 1 Received: 7 April 2020 / Accepted: 7 October 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract A base amount-dependent fluorescence enhancement-based strategy is put forward to determine vascular endothelial growth factor 165 (VEGF165) in human serum by the use of hairpin DNA-silver nanoclusters (hDNA-AgNCs) and oxidized carbon nanoparticles (CNPs). The hDNA-AgNCs aptasensing probe consists of AgNCs-contained hairpin loop (that generates a fluorescence signal), hairpin stem (that makes the structure stable), and the terminal aptamer 1 (that recognizes the target together with aptamer 2). It has been demonstrated that the fluorescence intensity of hDNA-AgNCs is ~ 3-fold stronger than that of single-stranded DNA-AgNCs (ssDNA-AgNCs), and hDNA-AgNCs have a strong dependence of fluorescence enhancement on the base amount in hairpin stem and loop. Upon the addition of oxidized CNPs, the terminal aptamer 1 of hDNA-AgNCs can adsorb onto the surface of oxidized CNPs via π-π stacking, and the fluorescence of hDNA-AgNCs (with excitation/emission maxima at 490/567 nm) is quenched via fluorescence resonance energy transfer (FRET). When aptamer 2 and VEGF165 are subsequently added, aptamer 1, VEGF165, and aptamer 2 reassemble into an intact tertiary structure, and the fluorescence is recovered because hDNA-AgNCs are far away from the surface of oxidized CNPs and the FRET efficiency decreases. Under the optimized conditions, the aptasensing probe can selectively assay VEGF165 with a detection limit of 14 pM. The results provide a label-free and sensitive method to monitor VEGF165 in human serum. Keywords Base amount-dependent fluorescence enhancement . DNA-silver nanoclusters . Oxidized carbon nanoparticles . Aptasensing probe . Cancer biomarker . VEGF165 . Serum analysis
Introduction Vascular endothelial growth factor (VEGF) is a hypoxiainducible protein [1] that includes five members (e.g., VEGFA, B, C, D, and placenta growth factor) [2]. Among them, VEGFA is usually referred to as VEGF, which has four isoforms including VEGF165 , VEGF189, VEGF121, and VEGF206 [3, 4]. In particular, VEGF165 accounts for the Jiangrong Ji and Xin Xu contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-020-04592-1) contains supplementary material, which is available to authorized users. * Shuhu Du [email protected] 1
School of Pharmacy, Nanjing Medical University, Nanjing 211166, Jiangsu, China
development and metastasis of a number of human tumors [5]. Its overexpression or downregulation is related with various sicknesses (such as lung, thyroid, breast, kidney, ovary, and bladder tumors). Thus, the VEGF is often used as a cancer bioma
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