Page 18 Motivation: Liquid Biopsies Circulating nucleic acids in the blood of cancer patients Blood vessel mRNA ctDNA miRNA Liquid biopsies are minimally invasive and can detect biomarkers without the requirement for a traditional biospy. Circulating mRNA are labile biomarkers and could provide temporal information on tumour state. The androgen receptor (AR) is a major oncogenic driver of prostate cancer. YAP1 mRNA is a marker of EMT in multiple cancer types, and its levels are reduced in metastatic castration-resistant prostate cancer. [1] How are we detecting mRNA? LAMP and ISFETs Loop-mediated isothermal amplification (LAMP) is an amplification technique that can be performed at one temperature (60 - 65oC). During an amplification event (i,.e mRNA is present) protons are released for each new nucleotide addition. (1) dNTP + dsDNAn= dsDNAn+1+ PPi +H+ Ion-sensitive field-effect transistors (ISFETs) can detect the rate of pH change. [2] In combination, these techniques can be utilised as a handheld device where the biosensor output can be recorded using a mobile phone. [3,4] ISFET biosensor with LAMP reaction on the array surface References (1): Selth, L. A. et al. A ZEB1-miR-375-YAP1 pathway regulates epithelial plasticity in prostate cancer. Oncogene 36, 24–34 (2017). (2): Moser, N., Rodriguez-Manzano, J., Lande, T. S. & Georgiou, P. A scalable ISFET sensing and memory array with sensor auto-calibration for on-chip realtime DNA detection. IEEE Transactions on Biomedical Circuits and Systems 12, 390–401 (2018). (3): Broomfield, J. et al. Handheld ISFET Lab-on-Chip Detection of TMPRSS2-ERG and AR mRNA for Prostate Cancer Prognostics. IEEE Sensors Letters 7, (2023). (4): Broomfield, J. et al. Detection of YAP1 and AR-V7 mRNA for Prostate Cancer Prognosis Using an ISFET Lab-On-Chip Platform. ACS Sensors 7, 3389– 3398 (2022). Handheld ISFET detection of YAP1 and Androgen Receptor mRNA from clinical samples for prostate cancer prognostics
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