Expansion Microscopy Using Swellable Hydrogel for Super-Resolution Imaging
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Solution Overview
Problem
Conventional optical microscopy is limited by the diffraction limit, making it difficult to achieve nanoscale resolution for imaging biological structures such as tissue sections and tumors, which require specialized techniques and equipment.
Innovation Solution
The method involves embedding biological specimens in a swellable polymer hydrogel, allowing for isotropic expansion, which enables imaging below the classical diffraction limit using standard optical microscopes, thereby achieving nanoscale precision without the need for specialized equipment or techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical microscopy is used, then imaging is simple and equipment is standard, but resolution is limited to approximately half the wavelength of the illuminating source (250-330 nm)
Solution Approach 1:
The patent applies dimensionality change by physically expanding the sample in three dimensions (isotropic expansion) rather than attempting to improve optical resolution in the traditional sense. By embedding the sample in a swellable hydrogel and expanding it 4-5x in linear dimensions, the patent transforms the resolution problem from an optical limitation to a physical scaling problem, allowing standard microscopes to achieve super-resolution effective imaging.
Solution Approach 2:
The patent changes the physical state and dimensions of the sample by using a swellable hydrogel matrix that can absorb water and expand isotropically. This parameter change (expansion factor of 4-5x) directly translates to improved effective resolution without requiring changes to the microscope's optical parameters or introducing complex super-resolution imaging techniques.
2Measurement precision
If super-resolution microscopy techniques are used, then resolution better than 250 nanometers down to 20 nm is achieved, but specialized equipment, expensive machines, and additional technical training are required
Solution Approach 1:
The patent creates a physical copy or replica of the original sample at expanded scale. By embedding the biological sample in a hydrogel and expanding the hydrogel, the patent produces an enlarged copy of the sample structure that can be imaged with standard equipment. This copying approach avoids the need for specialized super-resolution microscopy equipment while achieving comparable or superior effective resolution.
Solution Approach 2:
The patent segments the imaging problem into two independent parts: (1) sample preparation with hydrogel embedding and expansion, and (2) standard optical microscopy imaging. This segmentation allows the use of inexpensive, widely available microscopes while achieving super-resolution effective imaging through the expansion step, eliminating the need for specialized expensive equipment.
3Measurement precision
If super-resolution microscopy is applied to thick structures such as tissue sections or tumors, then high resolution imaging is attempted, but the techniques have difficulty penetrating and imaging deep within thick samples
Solution Approach 1:
The patent applies dimensionality change by physically expanding the thick sample in three dimensions, including the depth dimension (z-axis expansion factor of 3.8-4.2x). This expansion reduces the effective optical path length and improves light penetration, allowing standard microscopes to image deep within what would otherwise be too-thick samples. The isotropic expansion maintains structural relationships while making the sample accessible to standard imaging techniques.
4Measurement precision
If samples are physically expanded to achieve better resolution, then nanoscale precision imaging is enabled, but maintaining structural integrity and uniform expansion without artifacts is challenging
Solution Approach 1:
The patent uses a composite material system consisting of a crosslinked hydrogel matrix (e.g., polyacrylamide or polyacrylate) that provides mechanical stability and uniform expansion properties. The hydrogel is crosslinked with agents like N,N'-methylenebisacrylamide to create a stable network that expands isotropically while maintaining structural integrity. This composite approach ensures uniform expansion without artifacts and preserves the relative positions of biological structures.
Solution Approach 2:
The patent applies local quality by using enzymatic digestion (e.g., proteinase K treatment) to selectively remove specific biological components (proteins) while leaving the hydrogel matrix and embedded structures intact. This localized enzymatic treatment homogenizes the sample matrix, removes potential sources of non-uniform expansion, and preserves the structural relationships of interest while enabling uniform isotropic expansion.
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 effective imaging of features below the diffraction limit, enabling new scientific explorations and medical applications such as mapping the brain and personalized medicine, with minimal artifacts and using standard microscopy equipment.
Implementation Method 1
the composition comprises a polyelectrolyte hydrogel (or the components thereof), which can swell macroscopically, for example, in low-salt water
Data Source
AI summary
The present invention relates to an enlarged sample of interest for microscopy and methods for enlarging a sample of interest and the optical imaging of a sample of interest with resolution better than the classical microscopy diffraction limit, by synthesizing a swellable polymer network within a sample, it can be physically expanded, resulting in physical magnification.