Abstract
We describe the preparation and characterization of an aptamer-based electrochemical sensor to lung cancer tumor markers in human blood. The highly reproducible aptamer sensing layer with a high density (up to 70% coverage) on the gold electrode was made. Electrochemical methods and confocal laser scanning microscopy were used to study the stability of the aptamer layer structure and binding ability. A new blocking agent, a thiolated oligonucleotide with an unrelated sequence, was applied to fill the aptamer layer’s defects. Electrochemical aptasensor signal processing was enhanced using deep learning and computer simulation of the experimental data array. It was found that the combinations (coupled and tripled) of cyclic voltammogram features allowed for distinguishing between the samples from lung cancer patients and healthy candidates with a mean accuracy of 0.73. The capacitive component from the non-Faradic electrochemical impedance spectroscopy data indicated the tumor marker’s presence in a sample. These findings allowed for the creation of highly informative aptasensors for early lung cancer diagnostics.
Highlights
Electrochemical aptasensors are becoming popular in sensing a wide range of different analytes, from cells [1] and microorganisms [2], to small molecule biomarkers [3,4,5] and metal ions [6,7,8] in body fluids, food [13,14,15], and water [16,17]
The Cycling voltammetry (CV) and electrochemical impedance spectroscopy (EIS) data for each sample were transformed into a set of numerical feaThe CV and EIS data for each sample were transformed into a set of numerical tures
Differential-pulse kept in the blood plasma samples, and the LC-18 aptamer retained its ability of selectivevoltamme electrochemical impedance spectroscopy (EIS), square-wave voltammetry
Summary
Electrochemical aptasensors are becoming popular in sensing a wide range of different analytes, from cells [1] and microorganisms [2], to small molecule biomarkers [3,4,5] and metal ions [6,7,8] in body fluids (serum [9,10], urine [11], and saliva [12]), food [13,14,15], and water [16,17]. We first chose a reductive pretreatment to prepare an aptasensor based on the DNA aptamer LC-18 developed earlier for postoperative lung cancer tissues [40]. This aptamer has already proven its ability to bind to plasma lung cancer biomarkers [41], detect circulating tumor cells in blood [40], and selectively label cancer cells in lung tumors [41]. We, for the first time, suggested blocking the uncovered electrode surface with a new blocking agent—a short thiolated oligonucleotide with an unrelated sequence This blocking oligonucleotide has the same length as the linker binding the aptamer with gold. New BA was suggested and tested, enhancing the effectiveness of the signal processing of the electrochemical aptasensor using deep learning and computer simulation of the experimental data array
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