Related Experiment Video
Updated: Sep 27, 2025
A Microfluidic Chip for the Versatile Chemical Analysis of Single Cells
Published on: October 15, 2013
MIMAS: microfluidic platform in tandem with MALDI mass spectrometry for protein quantification from small cell
Jorvani Cruz Villarreal1,2, Rory Kruithoff3, Ana Egatz-Gomez1,2
1School of Molecular Sciences, Arizona State University, Temple, AZ, USA.
Abstract:
Understanding cell-to-cell variation at the molecular level provides relevant information about biological phenomena and is critical for clinical and biological research. Proteins carry important information not available from single-cell genomics and transcriptomics studies; however, due to the minute amount of proteins in single cells and the complexity of the proteome, quantitative protein analysis at the single-cell level remains challenging. Here, we report an integrated microfluidic platform in tandem with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for the detection and quantification of targeted proteins from small cell ensembles (> 10 cells). All necessary steps for the assay are integrated on-chip including cell lysis, protein immunocapture, tryptic digestion, and co-crystallization with the matrix solution for MALDI-MS analysis. We demonstrate that our approach is suitable for protein quantification by assessing the apoptotic protein Bcl-2 released from MCF-7 breast cancer cells, ranging from 26 to 223 cells lysed on-chip (8.75 nL wells). A limit of detection (LOD) of 11.22 nM was determined, equivalent to 5.91 × 107 protein molecules per well. Additionally, the microfluidic platform design was further improved, establishing the successful quantification of Bcl-2 protein from MCF-7 cell ensembles ranging from 8 to 19 cells in 4 nL wells. The LOD in the smaller well designs for Bcl-2 resulted in 14.85 nM, equivalent to 3.57 × 107 protein molecules per well. This work shows the capability of our approach to quantitatively assess proteins from cell lysate on the MIMAS platform for the first time. These results demonstrate our approach constitutes a promising tool for quantitative targeted protein analysis from small cell ensembles down to single cells, with the capability for multiplexing through parallelization and automation.
Insights
This study presents a microfluidic platform for quantifying proteins in small cell groups. The integrated system enables sensitive detection of proteins like Bcl-2 from cell ensembles, advancing single-cell proteomic analysis.
Area of Science:
- Biochemistry and Molecular Biology
- Analytical Chemistry
- Biotechnology
Background:
- Single-cell analysis is crucial for understanding biological heterogeneity.
- Quantitative protein analysis at the single-cell level is challenging due to low abundance and proteomic complexity.
- Existing methods often lack the sensitivity and integration required for precise single-cell proteomic quantification.
Purpose of the Study:
- To develop and validate an integrated microfluidic platform for sensitive, quantitative protein analysis from small cell ensembles.
- To demonstrate the platform's capability for detecting and quantifying specific proteins using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS).
- To assess the platform's performance with varying cell numbers and well volumes.
Main Methods:
- An integrated microfluidic chip was designed to perform on-chip cell lysis, protein immunocapture, tryptic digestion, and matrix co-crystallization.
- Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was employed for protein detection and quantification.
- The apoptotic protein Bcl-2 from MCF-7 breast cancer cells was used as a model analyte to validate the platform's performance.
Main Results:
- The platform successfully quantified targeted proteins from cell ensembles as small as 8-19 cells.
- A limit of detection (LOD) for Bcl-2 was determined to be as low as 11.22 nM (5.91 × 10^7 molecules per well) in 8.75 nL wells.
- Improved platform design achieved quantification from 8-19 cells in 4 nL wells with an LOD of 14.85 nM (3.57 × 10^7 molecules per well).
Conclusions:
- The developed microfluidic platform coupled with MALDI-TOF-MS provides a sensitive and quantitative method for targeted protein analysis from small cell ensembles.
- This approach overcomes limitations in single-cell proteomic analysis, offering a promising tool for biological and clinical research.
- The platform's potential for parallelization and automation suggests future applications in high-throughput single-cell proteomic studies.
