Graphene Oxide Affinity Grids for Cryo-EM Sample Integrity
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Solution Overview
Problem
Cryo-EM sample preparation methods are inefficient and prone to sample denaturation and aggregation due to exposure to the air-water interface, leading to poor resolution and limited data collection.
Innovation Solution
The use of graphene oxide (GO) films on cryo-EM grids, functionalized with various chemistries for diverse target species, and polyethylene glycol spacers to position samples away from the interface, enabling efficient and versatile sample preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cryo-EM sample preparation methods are used, then samples can be deposited on grids, but samples are exposed to air-water interface causing denaturation and aggregation
Solution Approach 1:
The patent introduces an affinity support film as an intermediary layer between the sample and the air-water interface. This film functionalized with affinity moieties (such as Ni-NTA, streptavidin, or antibodies) selectively binds to tagged samples, acting as a mediator that prevents direct contact between samples and the harmful air-water interface while maintaining sample integrity and reducing denaturation and aggregation.
2Productivity
If affinity grids are used to concentrate samples, then sample preparation efficiency improves, but sample aggregation may occur
Solution Approach 1:
The patent applies local quality by functionalizing only specific regions of the support film with affinity moieties, rather than uniformly across the entire surface. This localized functionalization allows samples to be concentrated at specific binding sites while maintaining overall sample homogeneity and preventing excessive aggregation. The support film can have different functional zones that guide sample distribution.
3Quantity of substance
If thick support films are used, then sample concentration is improved, but electron scattering increases reducing resolution
Solution Approach 1:
The patent employs thin film technology by using support films with thickness optimized for electron microscopy (typically 3-10 nm). These thin films provide sufficient mechanical support and sample concentration capability while minimizing electron scattering. The affinity moieties are attached to this thin film structure, enabling sample concentration without compromising image resolution due to excessive thickness.
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
Facilitates high-quality cryo-EM samples with diverse orientations, reducing denaturation and aggregation, allowing for high-resolution structural analysis of proteins and other biological specimens.
Implementation Method 1
graphene oxide (GO) films on cryo-EM grids
Implementation Method 2
polyethylene glycol spacers to position samples away from the interface
Implementation Method 3
the grid is plunged into liquid ethane and the biological samples are vitrified in amorphous ice
Implementation Method 4
plunged into liquid ethane to rapidly freeze and vitrify
Implementation Method 5
Transmission electron microscopy (TEM) is a versatile technique that can provide high resolution structural information
Data Source
AI summary
Herein are innovations that enable facile cryo-EM analysis of diverse samples. Methods of functionalizing sample grids for cryo-EM are described, including methods of creating high quality graphene oxide films on cryo-EM substrates. The cryo-EM sample substrates are functionalized with affinity molecules that efficiently concentrate sample molecules and other specimen types on the grid, away from the air-water interface. Affinity groups include amines and proteins such as tagging system proteins and peptides that can be used to capture diverse sample types with high affinity. Optionally, spacers such as PEG chains are used to place sample particles away from the substrate surface, reducing substrate-induced artifacts.