Keywords

microRNA; cancer; biosensor; biopsy; extraction; serum

Abstract

Lung cancer kills more people in the U.S. a year than any other cancer. This is largely because patients often remain asymptomatic until stage 3, by which time the tumor is usually highly malignant. High radiation-producing screenings are the current method of lung tumor detection. These typically involve machinery for tumor visualization, such as computed tomography (CT) scans, positron emission tomography (PET scan), magnetic resonance imaging (MRI), and X-rays. Not only does radiation exposure from this equipment pose a risk to the patient, but any tumors detected by these scanning techniques are likely to be locally advanced. This suggests that while the cancer may not be metastatic, it has likely caused significant damage to lung tissue and severe physical symptoms. More benign screening methods are currently being explored. For example, scientists are exploring the correlation between microRNA (miRNA) concentrations in blood and tumor development, which biosensors may be able to detect and quantify. miRNA strands are non-coding genetic material that are secreted when cells become inflamed, which occurs during tumor formation and growth. A gold disk electrode (GDE) utilizing a 5-strand 4-way-junction (5S4WJ) system was employed to hybridize target miRNA strands to the junction system, which then initiates a redox reaction with the gold surface when analyzed using square wave voltammetry (SWV), resulting in a current density signal. The 5S-4WJ forms only in the presence of the target miRNA strand, allowing it to distinguish the target from other non-target genetic material. Blood serum samples were prepared to enhance the current density signal while detecting miRNA using the biosensor system. Ethylenediamine tetraacetic acid (EDTA) and tris(2-carboxyethyl) phosphine hydrochloride (TCEP) were added to extracted blood serum samples to preserve miRNA structure and allow for signal enhancement. The results indicated that EDTA more effectively enhanced the current density signal when added to the serum/hybridization buffer (HB) samples. Multiple calibration curves were constructed to demonstrate the sensitivity of the electrodes in various samples (pure HB, serum/HB, and serum/HB/EDTA) when detecting target miRNA at differing concentrations. The proposed biosensor system holds promising implications for both clinical and point-of-care settings. The electrodes may be capable of early-stage cancer detection and diagnosis through liquid biopsy procedures, potentially replacing traditional screening methods and tissue biopsies. Due to the lack of sophistication of the biosensors and the equipment required, they may eventually be accessible in resource-limited settings where standard screening machinery is not attainable.

Thesis Completion Year

2024

Thesis Completion Semester

Summer

Thesis Chair

Chumbimuni-Torres, Karin

College

College of Sciences

Department

Chemistry

Thesis Discipline

Electrochemistry

Language

English

Access Status

Open Access

Length of Campus Access

None

Campus Location

Orlando (Main) Campus

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Rights Statement

In Copyright