Iterative Direct Expansion Microscopy for Thick-Tissue Imaging
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Solution Overview
Problem
Conventional optical microscopy is limited by a spatial resolution of 300 nm due to light diffraction, and existing super-resolution techniques face challenges in scalability to thick tissues and require expensive hardware, making them impractical for imaging complex biological systems like the brain.
Innovation Solution
Iterative direct expansion microscopy (id-ExM) uses electrostatic and mechanical forces to iteratively expand biological samples isotropically, achieving high expansion factors (20× to 100×) without the need for gel cleaving or specialized hardware, by anchoring biomolecules to a polymer network and swelling it, allowing super-resolution imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical microscopy is used, then imaging is simple and hardware is inexpensive, but spatial resolution is limited to 300 nm due to light diffraction
Solution Approach 1:
The patent creates a physical copy of the sample structure by embedding it in a swellable gel matrix that expands uniformly. This copying approach allows the original sample to be imaged at high resolution after expansion, avoiding the need for complex super-resolution optical hardware while achieving sub-diffraction resolution through physical enlargement of the sample structure.
Solution Approach 2:
The patent changes the physical state and size parameters of the sample by embedding it in a swellable gel and inducing expansion. This parameter change (volume increase) effectively magnifies the sample structures, allowing conventional optical microscopes to achieve super-resolution by imaging the expanded sample rather than requiring changes to the optical system itself.
2Measurement precision
If existing super-resolution optical techniques are used, then spatial resolution exceeds 300 nm, but they require expensive hardware and cannot be scaled to thick tissues
Solution Approach 1:
The patent segments the imaging process into two independent stages: sample preparation (embedding in swellable gel) and imaging. This segmentation allows the complex expansion process to be performed separately on thick tissue samples, and then the expanded sample is imaged with conventional microscopes, making the system scalable to thick tissues without requiring expensive optical hardware.
Solution Approach 2:
The swellable gel acts as an intermediary medium between the thick tissue sample and the conventional optical microscope. It physically expands the sample to achieve super-resolution while being compatible with conventional optical hardware, thus mediating between the need for high resolution and the constraints of simple, scalable imaging systems.
3Measurement precision
If iterative expansion microscopy involves transfer of biomolecules from one gel to another, then resolution is improved, but the process becomes complex and potentially non-compatible for imaging of RNA or biomolecular retention
Solution Approach 1:
The patent merges the expansion and imaging processes into a single integrated workflow where biomolecules are anchored to the swellable gel matrix during expansion, eliminating the need for separate transfer steps. This combining of operations simplifies the process while maintaining high resolution, making it compatible with RNA imaging and biomolecular retention applications.
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
id-ExM enables high-resolution imaging of biomolecules in thick tissues, preserving their spatial orientation and allowing comprehensive analysis without the need for expensive equipment, facilitating the study of complex biological systems like the brain.
Implementation Method 1
The sample is expanded isotropically in three dimensions using electrostatic and mechanical forces
Implementation Method 2
The sample is embedded in a swellable material... the sample can be expanded isotropically in three dimensions
Data Source
AI summary
The present invention provides biological samples of interest that have been iteratively expanded in a method referred to herein as iterative direct expansion microscopy (id-ExM). In the id-ExM method, biological samples of interest are permeated with a swellable material that results in the sample becoming embedded in the swellable material, and then the sample can be expanded isotropically in three dimensions. The process of iteratively expanding the samples can be applied to expand samples one or more additional times such that, for example, a 5-fold expanded sample can be expanded again to achieve high expansion factors, for example, 20× to 100× or more linear expansion.