On-chip surface acoustic wave lysis and ion-exchange nanomembrane detection of exosomal RNA for pancreatic cancer study and diagnosis

Abstract

There has been increasing evidence that micro and messenger RNA derived from exosomes play important roles in pancreatic and other cancers. In this work, a microfluidics-based approach to the analysis of exosomal RNA is presented based on surface acoustic wave (SAW) exosome lysis and ion-exchange nanomembrane RNA sensing performed in conjunction on two separate chips. Using microRNA hsa-miR-550 as a model target and raw cell media from pancreatic cancer cell lines as a biological sample, SAW-based exosome lysis is shown to have a lysis rate of 38%, and an ion-exchange nanomembrane sensor is shown to have a limit of detection of 2 pM, with two decades of linear dynamic range. A universal calibration curve was derived for the membrane sensor and used to detect the target at a concentration of 13 pM in a SAW-lysed sample, which translates to 14 target miRNA per exosome from the raw cell media. At a total analysis time of ~1.5 h, this approach is a significant improvement over existing methods that require two overnight steps and 13 h of processing time. The platform also requires much smaller sample volumes than existing technology (~100 μL as opposed to ~mL) and operates with minimal sample loss, a distinct advantage for studies involving mouse models or other situations where the working fluid is scarce.

Future microfluidic and nanofluidic modular platforms for nucleic acid liquid biopsy in precision medicine

“…4(d)). 119 These extensive studies clearly demonstrate the sensor is capable of rapidly quantifying miRNAs from 10 6 to 10 9 copies with minimum loss and high specificity. Its sensitivity exceeds conventional microarray assays by a factor of 10 2 -10 3 .…”

“…114,118,119 By reducing the sensing area from 0.25 mm 2 to 0.0625 mm 2 , we improved the LOD by 3 orders of magnitude (to 10 4 copies per 100 ll), at the expense of some robustness. Samples with different ionic strengths and miRNA-550 concentrations from 1 pM to 1 lM were tested on 5 different chips (Fig.…”

“…111,118,119 We have quantified miR146a and miR550 (oral and pancreatic cancer biomarkers, respectively) in raw cell culture lysate and culture media with and without off-chip RNA extraction steps. We have also successfully detected longer RNAs, including discrimination between two different dengue virus (DENV) serotype RNAs, and between Brucella RNA and two-base mismatch control samples.…”

“…119 Lysis was achieved via surface acoustic waves (SAWs), which are Rayleigh waves generated on the surface of a piezoelectric crystal by alternating current applied through an interdigitated electrode transducer. When the SAW waves interact with a bulk liquid droplet or film, scattered sound waves produce an acoustic pressure in the liquid bulk while the electric component of the wave produces an electric Maxwell pressure at the solid liquid interface.…”

Exosomes: A Cancer Theranostics Road Map

“…Today, advances in microfluidics lead to effective exosome separation, complementing liquid biopsies towards new-age theranostics. Detection and characterization are essential to the capture-to-diagnosis path, and thus, current efforts focus on the development of detection techniques [44,84,85] . Some methodologies even suggest the preparation-free detection of exosomal RNA from raw cell culture media, allowing for promising biofluid applications [85] .…”