Abstract
It is well-known that two major issues, preventing improved outcomes from cancer are late diagnosis and the evolution of drug resistance during chemotherapy, therefore technologies that address these issues can have a transformative effect on healthcare workflows. In this work we present a simple, low-cost DNA biosensor that was developed specifically to detect mutations in a key oncogene (KRAS). The sensor employed was a screen-printed array of carbon electrodes, used to perform parallel measurements of DNA hybridisation. A DNA amplification reaction was developed with primers for mutant and wild type KRAS sequences which amplified target sequences from representative clinical samples to detectable levels in as few as twenty cycles. High levels of sensitivity were demonstrated alongside a clear exemplar of assay specificity by showing the mutant KRAS sequence was detectable against a significant background of wild type DNA following amplification and hybridisation on the sensor surface. The time to result was found to be 3.5 h with considerable potential for optimisation through assay integration. This quick and versatile biosensor has the potential to be deployed in a low-cost, point-of-care test where patients can be screened either for early diagnosis purposes or monitoring of response to therapy.
Highlights
Cancer is by nature a genetic disease, arising from random mutations and DNA damage which once reaching a certain threshold result in cellular malfunction
Generation Oil were obtained from BioRad Laboratories Ltd., UK
In order to evaluate the specificity of the assay, we explored the ability of the probe-modified electrodes to discriminate between G12D mutant and wild type KRAS sequences
Summary
Cancer is by nature a genetic disease, arising from random mutations and DNA damage which once reaching a certain threshold result in cellular malfunction. Detection of cancer is based mainly on clinical presentation of symptoms, which often are vague and non-descript. The time point at which a tumour manifests clinical symptoms often correlates with the later stages of progression (e.g., Phases III and IV) where surgery and therapy are less effective because of e.g., metastasis or tumour cells acquiring a critical mass of mutations [1]. A concept that is gaining increasing traction in cancer diagnosis is the idea of ‘liquid biopsy’ [2]. This is where liquid samples, such as blood [3], urine [4], cerebrospinal fluid etc., are assayed for biomarkers of cancer.
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