Tip-Enhanced Laser Ablation for Submicron Biomolecule Transfer
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Solution Overview
Problem
Current mass spectrometry techniques face limitations in achieving high spatial resolution for imaging biomolecules, particularly with MALDI, which is restricted by the diffraction limit and optical configurations, and near-field optics have shown promise but with low efficiency and redeposition of desorbed material.
Innovation Solution
The use of tip-enhanced laser ablation with an atomic force microscope to capture molecules from a surface onto a wire, allowing for submicron spatial resolution and efficient transfer to a mass spectrometer without fragmentation, utilizing a gold-coated silicon tip and pulsed lasers to create craters for molecule collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MALDI mass spectrometry imaging is used to obtain mass spectra of large biomolecules, then the spatial resolution is limited to 5 to 200 μm due to diffraction limit and optical configurations
Solution Approach 1:
The patent extracts the sample transfer function from the traditional MALDI optical path by using a physical probe (atomic force microscope tip or capillary) to collect ablated material directly from the sample surface and transport it to the mass spectrometer, thereby eliminating the diffraction limit imposed by optical configurations
Solution Approach 2:
The patent introduces an intermediary probe (atomic force microscope tip or capillary) that acts as a mediator between the sample surface and the mass spectrometer, enabling direct material transfer without relying on diffraction-limited optical paths
2Measurement precision
If near-field optics are used for laser ablation, then spatial resolution can be improved but efficiency is low and desorbed material is redeposited
Solution Approach 1:
The patent uses a physical probe as an intermediary to collect ablated material directly at the ablation site, preventing redeposition of desorbed material onto surrounding areas and improving both spatial resolution and transfer efficiency
Solution Approach 2:
The patent replaces the optical field-based near-field approach with a mechanical probe-based collection system, where the physical contact or close proximity of the probe to the sample surface enables efficient material collection without the redeposition problems inherent in optical methods
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 method enables the transfer of amol quantities of peptides and proteins with spatial resolutions less than 1 μm, achieving efficient sample collection and analysis while minimizing fragmentation, and allows for single-cell imaging capabilities.
Implementation Method 1
a pulsed laser is focused onto a tip to ablate molecules from spots on a sample surface
Implementation Method 2
The tip can act as an antenna for the electromagnetic radiation and enables the ablation of the sample with an ablation spot size that is much smaller than if the pulsed laser were focused with a conventional lens system
Implementation Method 3
The ablated material can be collected on a capillary tube or wire that is suspended above the sample surface
Data Source
AI summary
Disclosed are various embodiments for transferring molecules from a surface for mass spectrometry and other sample analysis methods, and the like. A laser is focused onto a tip of an atomic force microscope to remove and capture a quantity of molecules from the surface, so they can be transferred to a mass spectrometer or another instrument for analysis.