Visual and Highly Sensitive Detection of Cancer Cells by a Colorimetric Aptasensor Based on Cell-Triggered Cyclic Enzymatic Signal Amplification

Abstract

Rapid and efficient detection of cancer cells at their earliest stages is one of the central challenges in cancer diagnostics. We developed a simple, cost-effective, and highly sensitive colorimetric method for visually detecting rare cancer cells based on cell-triggered cyclic enzymatic signal amplification (CTCESA). In the absence of target cells, hairpin aptamer probes (HAPs) and linker DNAs stably coexist in solution, and the linker DNA assembles DNA-AuNPs, producing a purple solution. In the presence of target cells, the specific binding of HAPs to the target cells triggers a conformational switch that results in linker DNA hybridization and cleavage by nicking endonuclease-strand scission cycles. Consequently, the cleaved fragments of linker DNA can no longer assemble into DNA-AuNPs, resulting in a red color. UV-vis spectrometry and photograph analyses demonstrated that this CTCESA-based method exhibited selective and sensitive colorimetric responses to the presence of target CCRF-CEM cells, which could be detected by the naked eye. The linear response for CCRF-CEM cells in a concentration range from 10(2) to 10(4) cells was obtained with a detection limit of 40 cells, which is approximately 20 times lower than the detection limit of normal AuNP-based methods without amplification. Given the high specificity and sensitivity of CTCESA, this colorimetric method provides a sensitive, label-free, and cost-effective approach for early cancer diagnosis and point-to-care applications.

Plasmonic molecular assays: Recent advances and applications for mobile health

“…Use of plasmonic nanoparticles as colorimetric reporters is a common strategy to enable sensitive and rapid readout with a simple instrument, or even with the naked eye. Au NP reporters have been used in many isothermal amplification methods including CEA [124][125][126], LAMP [127][128][129], RCA [130], HCR [131,132], CHA [133], and other DNA machinery [134,135]. Nano Res.…”

Highly sensitive and specific colorimetric detection of cancer cells via dual-aptamer target binding strategy

“…In previous reports, the detection limit of colorimetric cancer cell detection is reduced from 800 cells to 125 cells (Zhang et al, 2014a) due to the intrinsic property of nanomaterials. Recently, a detection limit of 40 cells for visual cancer cell detection is reached according to cell-triggered cyclic enzymatic signal amplification strategy (Zhang et al, 2014b). With our proposed strategy, the detection sensitivity is significantly improved and 10 cells/mL can be clearly distinguished by naked eyes on the basis of the synergistic action of high catalytic activity of PtAu NP and magnetic separation and concentration.…”

“…Gold nanoparticle (Au NP ) has been confirmed to be excellent candidate for colorimetric sensors due to its distance-dependent surface plasmon resonance (SPR) adsorption property Medley et al, 2008;Valentini et al, 2013;Xu et al, 2009). While, the distance-dependence intrinsic property of Au NP limits its applications in early cancer diagnosis in that the color change of Au NP would be hardly monitored in case of a relatively low density of biomarkers on the cancer cell membrane (Lu et al, 2010;Shlyahovsky et al, 2007;Xie et al, 2012;Zhang et al, 2014b). To improve detection sensitivity, signal amplification strategies have been developed.…”

“…To improve detection sensitivity, signal amplification strategies have been developed. In very recently, a detection limit of 40 cells/mL for colorimetric detection was reached by combining cyclic signal amplification assay under the help of nicking endonuclease (Zhang et al, 2014b). By making use of catalytic activity of platinum nanoparticle on colorimetric reaction of chromogenic substrates, a detection limit of 30 cells was obtained according to the calculation of three times the standard deviation (3s) (Zhang et al, 2014a).…”

Aptamers as smart ligands for nano-carriers targeting

“…Magnetic nanoparticles [105], quantum dots [106], gold nanostructures [107] are the most to develop label free [108][109][110], in addition to the fluorescence [111] or chemiluminescence 244 [112] based aptasensors. Aptasensors, generally, exhibited good selectivity and sensitivity with 245 picomolar to nanomolar range for limit of detection (LOD) in sensing cancer specific antigens 246 [113,114].…”