System Modularity Chip for Analysis of Rare Targets (SMART-Chip): Liquid Biopsy Samples

Abstract

Liquid biopsies are becoming popular for managing a variety of diseases due to the minimally invasive nature of their acquisition, thus potentially providing better outcomes for patients. Circulating tumor cells (CTCs) are among the many different biomarkers secured from a liquid biopsy, and a number of efficient platforms for their isolation and enrichment from blood have been reported. However, many of these platforms require manual sample handling, which can generate difficulties when translating CTC assays into the clinic due to potential sample loss, contamination, and the need for highly specialized operators. We report a system modularity chip for the analysis of rare targets (SMART-Chip) composed of three taskspecific modules that can fully automate processing of CTCs. The modules were used for affinity selection of the CTCs from peripheral blood with subsequent photorelease, simultaneous counting, and viability determinations of the CTCs and staining/imaging of the CTCs for immunophenotyping. The modules were interconnected to a fluidic motherboard populated with valves, interconnects, pneumatic control channels, and a fluidic network. The SMART-Chip components were made from thermoplastics via microreplication, which lowers the cost of production making it amenable to clinical implementation. The utility of the SMART-Chip was demonstrated by processing blood samples secured from colorectal cancer (CRC) and pancreatic ductal adenocarcinoma (PDAC) patients. We were able to affinity-select EpCAM expressing CTCs with high purity (0−3 white blood cells/mL of blood), enumerate the selected cells, determine their viability, and immunophenotype the cells. The assay could be completed in <4 h, while manual processing required >8 h.

Exploring the Clinical Utility of Pancreatic Cancer Circulating Tumor Cells

“…Other microfluidic devices have reached higher than 80% detection rates [64,65]. Recently, SMART-Chip, an automated, modular microfluidic device incorporating impedance and imaging for rapid confirmation of the isolated cells, found CTCs in a PDAC patient as a proof-of-principal study [66]. Unfortunately, the limitation with this strategy of isolation, using their physical property, is that CTCs have been found to be equal or smaller in size to nucleated blood cells (ranging between 4 and 30µm) so specificity may be low [67,68].…”

Application of Microfluidics in Detection of Circulating Tumor Cells

“… Wang J. et al (2021) ) introduced a gas driving device into the integrated CTCs separation, immunofluorescence staining, and imaging system, which greatly reduced the time and reagent consumption and was able to capture and recognize CTCs within 90 min. The smart chip developed by Pahattuge et al (2021) integrates CTCs sorting, cell counting, and immunofluorescence imaging modules, which realizes the fully automatic operation of the separation and detection of CTCs in blood and avoids human interference ( Figure 7B ).…”

“… On-chip detection of CTCs (A) Overall strategy for CTC isolation and single-cell secretome analysis ( Deng et al, 2014 ); (B) A system modularity chip for the analysis of rare targets (SMART-Chip) ( Pahattuge et al, 2021 ); (C) A 3-step process for blood sample solutions with RANs labeled CCSCs and CTCs (Cho et al, 2018); (D) A multifunctional nanosphere-mediated microfluidic platform for multiplex biomarker profiling of heterogeneous CTCs (Wu et al, 2020); (E) The working principle of the aptamer-conjugated PtNPs with volumetric bar-chart chip readout for quantifiable visual detection of CTCs ( Abate et al, 2019 ) . …”

Multichannel Impedance Cytometry Downstream of Cell Separation by Deterministic Lateral Displacement to Quantify Macrophage Enrichment in Heterogeneous Samples

“…The overview layout of the respective sections of this integrated device is in Figure 1, including DLD separation along zigzag versus displaced streamlines based on designed critical size (or D c ) (Figure 1A) per magnified views for the inlets (Figure 1B), the outlets (Figure 1C), and on-chip impedance cytometry (Figure 1D) to measure impedance magnitude (|Z|) and impedance phase (φZ) over several simultaneously applied frequencies, with off-chip validation of the collected fractions (Figure 1E). Integration of impedance cytometry downstream of inertial separation has been presented, [10,34] but the flow rate mismatch has motivated modular platforms [35] or alternate cytometry methods, [36] that require extensive device footprints. On the other hand, the operating ranges for flow rate and sample throughput of DLD and impedance cytometry have a high degree of overlap, but their integration presents other challenges.…”