Single-walled carbon nanotube-gold urchin nanohybrid for identifying gastric cancer on dimicroelectrodes junction

Highlights

• SRY-box gene-17 for gastric cancer progression tested on microelectrodes sensor.

• Single-walled carbon nanotube & goldurchin modified on microelectrode junction.

• FESEM and FETEM revealed these nanomatarials to be used for dose-dependent analysis.

• LOD at 1 aM, on linear curve (pico to micro-molar) with regression coefficient ‘R2’.

• High-performance was shown by target-spiked serum and control experiments.

Abstract

Diagnosing gastric cancer with a high accuracy helps in identifying at early stage and for a better treatment. A transcription factor, SRY-box containing gene-17 (SOX-17) shows a crucial role in the gastric cancer progression is desired as biomarker on a high-performance sensing platform, dimicroelectrodes Junction (DMEJ), constructed by the hybrid of single-walled carbon nanotube (SWCN) and gold urchin (GU) surface to detect the specific SOX-17 target oligonucleotide. SWCN was modified on DMEJ and GU conjugated capture DNA was immobilized on SWCN through the electrostatic interaction of GU by (3-Aminopropyl)triethoxysilane. Morphological analyses by FESEM and FETEM revealed the attachment of GU on SWCN with a uniform fashion. SWCN-GU modified DMEJ has enhanced an ideal electric flow and reflecting the capture DNA attachment. Reached the limit of detection at 1 aM, calculated on a linear curve (atto- to femto-molar) with the regression coefficient of R² = 0.9909[y = 1.1226x + 1.3727]. Further, specificity of SOX-17 was confirmed by interacting complementary, single- and five-mismatched sequences of the target. In addition, the target DNA solution mixed human serum and control sequences did not interfere with the specific duplex formation, indicating the non-biofouling on DMEJ surface. This SWCN-GU constructed DMEJ surface helps to identify lower expression of SOX-17 and diagnosing gastric cancer progression.

Introduction

Gastric cancer is a stomach cancer found as one of the common lethal malignancies, developing in the gastrointestinal area and the second cause of cancer related death. [1,2] Different factors including, Helicobacter pylori infection, smoking, obese and eating habit of salty food are the main cause of gastric cancer. Due to the poor and late diagnosing, the survival rate of gastric cancer is low, so that an urgent need to develop a sensitive diagnose system with a suitable biomarker is mandatory. The current research was focusing to identify the SRY box containing gene-17 (SOX-17) sequence by a suitable capture sequence to diagnose the gastric cancer. SOX-17 gene is the transcription factor undergoes the process of DNA methylation and the expression of SOX-17 is closely related with gastric cancer. [3], [4], [5] Research has been demonstrated that the down-regulation of SOX-17 in the MKN45 gastric cancer cell. [3] The results proved that the siRNA-mediated lowering SOX-17 expression increases the multiplication of MKN45 cell line and removes the low-abundance of SOX-17 is the indication of gastric cancer. The current study is focusing to identify the SOX-17, because it exhibits a CpG island in its promoter region and found to be related with both “Cancer” and “Wnt/β-catenin signaling pathway” in gastric neoplasia. Moreover, it was found that, silencing of SOX-17 occurs at the initial stage gastric play a major part in the process of gastric cancer. [5] Herein, investigation was performed to detect the targeted DNA of SOX-17 sequence on dimicroelectrodes junction (DMEJ) to diagnose the gastric cancer.

Different dimicroelectrodes (DMEs) have been widely applied in electrochemical sensors due to their excellent electrical flow and conductivity upon attaching/interacting the biological molecules on the sensing surfaces [6], [7], [8]. Various targets, such as DNA, protein, RNA, aptamer and antibody were identified on DMEs to diagnose different diseases, such as influenza, ovarian cancer, diabetes, Parkinson's, lung cancer, Alzheimer and clotting deficiencies. [9], [10], [11], [12], [13] In DMEs, electrical signal is generated with variations on the sensing material as the transducer upon binding the desired target/analyte to be identified. A new single-walled carbon nanotube (SWCN) modified DMEs junction (DMEJ) was constructed here to identify the target DNA sequence from SOX-17.

In recent years, nanostructures with one-dimension such as, nanosphere, nanowire, carbon nanotube have been successfully utilized for sensing the biological elements. Various researchers were demonstrated the detection of small molecule, intact cell and protein by using biosensors and efficiently used with carbon nanotube and nanowire as the active transducers. [14] SWCN is with a hollow cylindrical shape composed of carbon atoms and rolled graphite, an excellent material to construct the analytical devices and proved in improving the sensing strategies due to its structural flexibility, biocompatibility, high electrical conductivity and low capacitance. SWCN-modified electrical device can efficiently identify various target molecules with nucleic acid, glucose, and smaller peptide/protein. [15], [16], [17] Moreover, it has been proved that SWCN and gold assembly on the sensing surfaces facilitate the response with electrical current for generating higher sensitivity. By considering the combination of SWCN and gold nanostructure, capture DNA sequence from SOX-17 gene was conjugated on gold urchin (DNA-GU) and attached on SWCN constructed DMEJ to improve the detection of target DNA.

Gold is a versatile material, received a tremendous attraction in the biosensor field due to its specific tunable optical property. Gold nanomaterial represents an extraordinary platform for developing analytical devices in biosensor and demonstrated for a wide range of applications, identified smaller molecule to the whole cell in chemical to biological fluids. [18,19] The surface of gold nanomaterial can easily be manipulated for a particular application, which includes chemical sensing, recognition of biomolecule and imaging [20], [21], [22]. In this research, thiol-ended capture DNA was conjugated (DNA-GU) and this hybrid helps to attach the higher number of capture probes on the sensing surface and increases the electrical flow, which ultimately improve the detection of target. [23,24] The DNA-GU immobilization process was monitored through the changing in current response. On the DNA-GU modified surfaces, dose-dependent target DNA was detected to find out the performance of the sensor.