Microfluidic ESI-MS Data Correlation for Intact Protein Analysis
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Solution Overview
Problem
Current methods for interfacing protein sample preparation techniques with mass spectrometry, such as liquid chromatography and electrospray ionization, face limitations in handling intact proteins and maintaining stable voltage conditions, leading to restricted utility and poor characterization of analyte fractions.
Innovation Solution
A computer-implemented method and system that converts mass spectra data into deconvoluted mass signal intensity plots, integrates isoelectric focusing images with mass spectrometry data, and adjusts dimensions to generate plots correlating isoelectric points with mass and time, enabling improved characterization and correlation of analyte peaks using a single integrated microfluidic device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If liquid chromatography is used to prepare protein samples for mass spectrometry, then sample fractions can be collected and analyzed, but the proteins must be digested into peptide fragments resulting in a large number of fractions and complex data reconstruction
Solution Approach 1:
The patent extracts and removes the protein digestion step from the sample preparation workflow. By using native mass spectrometry to analyze intact proteins directly, the complex process of digesting proteins into peptides and reconstructing data from multiple fractions is eliminated, while still achieving comprehensive analyte characterization
Solution Approach 2:
The patent segments the analysis by separating different protein isoforms and post-translational modifications into distinct focused zones within the microfluidic device, allowing each to be detected and characterized individually without requiring complete digestion and fractionation
2Ease of operation
If capillaries are used for electrospray ionization, then a convenient droplet volume can be achieved, but the linear flow path does not allow for multi-step sample processing
Solution Approach 1:
The patent merges multiple sample processing functions (isoelectric focusing, fraction collection, and electrospray ionization) into a single integrated microfluidic device. This combination allows multi-step sample processing while maintaining convenient droplet volumes for electrospray through the preserved capillary geometry at the emission interface
Solution Approach 2:
The microfluidic device is designed with multi-functionality, serving as both a separation chamber for isoelectric focusing and an electrospray ionization source. The device can perform sample preparation and analysis in a single platform, enhancing versatility while maintaining ease of operation through unified design
3Power
If electrospray ionization voltage is increased to improve ionization efficiency, then more ions are produced for detection, but internal fluid resistances change over time altering the voltage drop and changing the voltage at the ESI tip
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the voltage at the electrospray tip and adjusts the applied voltage to compensate for changes in internal fluid resistance. This feedback mechanism maintains stable ionization conditions over time, preserving both ionization efficiency and voltage stability
Solution Approach 2:
The patent employs dynamic voltage adjustment where the electrospray voltage is not held constant but is instead actively modulated in response to changing fluid resistance conditions. This dynamic approach allows the system to adapt to temporal changes while maintaining optimal ionization performance
4Ease of operation
If microfluidic devices are used for sample preparation, then additional control and complexity for fluid manipulation is achieved, but there is limited characterization of separated analyte fractions prior to introduction to mass spectrometer
Solution Approach 1:
The patent employs UV-Vis absorbance imaging to detect and characterize analyte fractions within the microfluidic device. Different proteins and modifications exhibit characteristic absorbance spectra, allowing identification and characterization of separated fractions based on their optical properties before mass spectrometry analysis
Solution Approach 2:
The patent introduces UV-Vis absorbance imaging as an intermediary detection method between the microfluidic separation process and mass spectrometry analysis. This intermediary provides real-time characterization of analyte fractions, preserving information about separation quality and protein properties before the final MS detection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for more accurate characterization of separated analyte peaks and improved correlation between chemical separation and mass spectrometry data, enhancing the quality of electrospray ionization mass spectrometry results and facilitating the analysis of protein isoforms and post-translational modifications.
Implementation Method 1
electrospray ionization (ESI). In ESI, small droplets of sample and solution are emitted from a distal end of a capillary or microfluidic device comprising an electrospray feature, such as an emitter tip or orifice, by the application of an electric field between the capillary tip or emitter tip and the mass spectrometer source plate. The droplet stretches and expands in this induced electric field to form a cone shaped emission (i.e., a 'Taylor cone') which comprises increasingly small droplets that evaporate and produce the gas phase ions
Implementation Method 2
a third data set comprises one or more images of an isoelectric focusing of one or more analytes, wherein each pixel of the one or more images corresponds to a signal intensity at a position and/or time, and wherein the position and/or time corresponds to at least one isoelectric point (pI) for the one or more analytes
Data Source
AI summary
Methods, devices, and systems for improving the quality of electrospray ionization mass spectrometer (ESI-MS) data are described, as are methods, devices, and systems for achieving improved correlation between chemical separation data and mass spectrometry data.