Design of a printed electrochemical strip towards miRNA-21 detection in urine samples: optimization of the experimental procedures for real sample application

Abstract

MicroRNAs (miRNAs) are clinical biomarkers for various human diseases, including cancer. They have been found in liquid biopsy samples, including various bodily fluids. They often play an important role in the early diagnosis and prognosis of cancer, and the development of simple and effective analytical methods would be of pivotal importance for the entire community. The determination of these targets may be affected by the different physicochemical parameters of the specimen of interest. In this work, an electrochemical detection platform for miRNA based on a screen-printed gold electrode was developed. In the present study, miRNA-21 was selected as a model sequence, due to its role in prostate, breast, colon, pancreatic, and liver cancers. A DNA sequence modified with methylene blue (MB) was covalently bound to the electrochemical strip and used to detect the selected target miRNA-21. After optimization of selected parameters in standard solutions, including the study of the effect of pH, the presence of interferent species, and NaCl salt concentration in the background, the application of square-wave voltammetry (SWV) technique allowed the detection of miRNA-21 down to a limit in the order of 2 nM. The developed device was then applied to several urine samples. In this case too, the device showed high selectivity in the presence of the complex matrix, satisfactory repeatability, and a limit of detection in the order of magnitude of nM, similarly as what observed in standard solutions.

Paper-Based Analytical Devices for Cancer Liquid Biopsy

“…It is important to use proteins in the design of cheap and portable paper-based detection devices for use in resource-limited parts of the world. The biomarker PSA in one specific application, the colorimetric paper detection technique, improves cancer detection methods of prostate studies. , Its primary purpose revolves around detecting prostate cancer and monitoring its progression . Alizadeh et al developed a simple paper sensor to detect CEA using a Co 2 (OH) 2 CO 3 –CeO 2 nanocomposite with peroxidase-like abilities and functionalized antibodies in an ionic liquid/chitosan solution.…”

Point‐of‐Care Testing for the Detection of MicroRNAs: Towards Liquid Biopsy on a Chip

“…[40] A recent example has been reported concerning the prostate cancer, which describes the electrochemical detection of miRNA-21 in urine samples using a gold screen-printed electrode with limit of detection in the low nanomolar range, demonstrating a promising tool for cancer management. [33] The strength of this architectures relies on the possibility to have all the system, both the recognizing oligonucleotides and the redox mediator, i.e. MB, immobilized on the portable device.…”

Point‐of‐Care Testing for the Detection of MicroRNAs: Towards Liquid Biopsy on a Chip

“…As described by the pioneering protocol of Plaxco et al., the use of recognition oligonucleotides modified with methylene blue (MB), a redox mediator, has been applied towards the detection of multiple miRNAs in biological fluids [40] . A recent example has been reported concerning the prostate cancer, which describes the electrochemical detection of miRNA‐21 in urine samples using a gold screen‐printed electrode with limit of detection in the low nanomolar range, demonstrating a promising tool for cancer management [33] . The strength of this architectures relies on the possibility to have all the system, both the recognizing oligonucleotides and the redox mediator, i.e.…”