Simple “Signal‐Off” Electrochemical Aptasensor Based on Aptamer‐Cu₃(PO₄)₂ Hybrid Nanoflowers/Graphene Oxide for Carcinoembryonic Antigen Detection

Abstract

A signal-off aptasensor was described based on well-designed aptamer-Cu 3 (PO 4 ) 2 hybrid nanoflowers&graphene oxide composites (aptamer-Cu 3 (PO 4 ) 2 HNF&GO) as an effective sensing platform and molybdophosphate precipitation as the signaling element. The aptamer, as the biorecognition unit grafted on aptamer-Cu 3 (PO 4 ) 2 HNF&GO by the specificity of streptavidin and biotin, captured the carcinoembryonic antigen (CEA) through specific interaction. The molybdophosphate precipitation were formed by the reaction of the aptamer-Cu 3 (PO 4 ) 2 HNF&GO with molybdate (MoO 4 2 À ). However, the CEAaptamer bioconjugate layer films not only hinder electron transfer on the sensing interface, but also impede the formation of molybdophosphate precipitation, resulting that the current signal significantly decreased. So, a simple aptasensor for CEA was constructed with high sensitivity and signal-off model. Under optimal experimental conditions using square wave voltammetry (SWV), the response peak currents decreases linearly with the logarithm of CEA concentrations in the range from 10 fg mL À 1 to 500 ng mL À 1 . Also, the feasibility of its applications has also been demonstrated in the analysis of clinical serum samples.

Design Strategies for Electrochemical Aptasensors for Cancer Diagnostic Devices

“…A variety of nanomaterials and nanocomposites was used both for the aptamer immobilisation and labelling: graphene-based nanomaterials [ 247 , 248 , 249 , 250 , 251 , 252 , 253 , 254 , 255 , 256 ], nanocomposite Zr metal–organic frameworks with Ag nanoclusters [ 257 ], and avidin-gated mesoporous silica nanoparticles [ 258 ].…”

“…The Cu 3 (PO 4 ) 2 nanoflowers/GO nanocomposites (Cu 3 (PO 4 ) 2 NF@GO) represented another platform for the biotinylated DNA aptamer immobilisation, via the biotin—streptavidin linkage [ 255 ]. The reaction of molybdophosphate precipitation from Cu 3 (PO 4 ) 2 NF@GO and molybdate (MoO 4 2− ) electrochemistry were used as an indicator.…”

“…The reaction of molybdophosphate precipitation from Cu 3 (PO 4 ) 2 NF@GO and molybdate (MoO 4 2− ) electrochemistry were used as an indicator. CEA binding to the aptamer hindered the molybdophosphate formation and decreased the electrochemical signal from molybdite, changing linearly with the CEA logarithmic concentration in the range from 10 fg mL −1 to 500 ng mL −1 (LOD of 2.4 fg mL −1 ) [ 255 ].…”

<p>Simultaneous Detection of VEGF and CEA by Time-Resolved Chemiluminescence Enzyme-Linked Aptamer Assay</p>

“…[36][37][38] Referring to the existing studies of VEGF 165 and CEA aptamers, the aptamer sequences designed in this study are shown in Table 1. [39][40][41][42] The VEGF 165 and CEA aptamers have been proved to bind to their corresponding targets with high affinity, respectively. And the great dissociation constant (Kd) values of the VEGF 165 and CEA aptamers were indeed already demonstrated, with a Kd value of 37.9 nM for VEGF 165 and 5 nM for CEA.…”