STED Microscopy Imaging Molecular Strand Alignment
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Solution Overview
Problem
Current methods for imaging molecular strands, such as DNA, lack sufficient control and accuracy, particularly in one-dimensional scanning, which is essential for precise imaging of one-dimensional objects, and struggle with high protein densities and concentrations found in cellular environments.
Innovation Solution
The method involves extending the molecular strand along a one-dimensional trapping line, using a probe beam for scanning parallel to the trapping line, and employing stimulated emission depletion (STED) microscopy with a depletion profile shaped as a line or plane perpendicular to the trapping line to enhance resolution and reduce beam alignment sensitivity, while optical traps are used to manipulate and align the strand for improved control and tension application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard fluorescence microscopy is used for imaging molecular strands, then the imaging process is simple, but the resolution is limited by diffraction and lacks precision for one-dimensional scanning
Solution Approach 1:
The imaging system is segmented into distinct functional modules: optical traps for strand manipulation, STED microscopy for super-resolution imaging, and one-dimensional scanning mechanisms. This segmentation allows each component to be optimized independently while maintaining overall system coherence, resolving the contradiction between high precision and complexity.
Solution Approach 2:
The patent transitions from conventional two-dimensional wide-field fluorescence microscopy to one-dimensional scanning along the molecular strand axis. This dimensional reduction enables precise localization along the strand while using STED to achieve super-resolution perpendicular to the scan direction, effectively bypassing diffraction limits without requiring full two-dimensional super-resolution capability.
2Measurement precision
If optical traps are used to extend and align the molecular strand, then control and alignment precision improve, but the system complexity increases
Solution Approach 1:
The patent merges optical trapping functionality with the fluorescence microscopy system, allowing the same optical apparatus to perform both mechanical manipulation of the molecular strand and high-resolution imaging. This integration reduces overall system complexity while maintaining alignment precision, as the trapping beams and imaging beams share common optical paths and focal regions.
3Measurement precision
If STED microscopy with depletion profile is used, then resolution beyond diffraction limit is achieved, but sensitivity to beam misalignment increases
Solution Approach 1:
The depletion profile is designed with non-uniform intensity distribution, creating a localized region of enhanced resolution along the scanning line while maintaining robustness against misalignment in perpendicular directions. This local quality enhancement allows super-resolution imaging without requiring perfect alignment across the entire beam profile.
4Productivity
If one-dimensional scanning is implemented for imaging molecular strands, then imaging speed and accuracy improve, but the ability to capture three-dimensional structural information is reduced
Solution Approach 1:
The system employs periodic scanning of the excitation focus along the molecular strand, repeatedly traversing the same one-dimensional path. This periodic action enables rapid data acquisition for constructing high-resolution images of the strand structure, while the confocal geometry maintains sensitivity to out-of-focus light to provide indirect three-dimensional structural context.
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 accurate, high-resolution imaging of molecular strands with enhanced localization precision and temporal resolution, enabling the visualization of individual proteins on DNA at sub-diffraction limits, even in high protein concentrations, bridging the gap between idealized and in vivo conditions, and providing insights into DNA-protein interactions.
Implementation Method 1
optical traps to manipulate and align the strand for improved control and tension application
Implementation Method 2
employing stimulated emission depletion (STED) microscopy with a depletion profile shaped as a line or plane perpendicular to the trapping line to enhance resolution
Implementation Method 3
an excitation of a fluorophore FL on the strand MS by the excitation focus EF results in a fluorescence response FR
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
The present disclosure concerns a method and system for imaging a molecular strand (MS). The method comprises - providing a sample volume (SV) comprising the strand (MS); - providing an excitation beam (EB) having an excitation focus (EF) with an excitation profile in the sample volume (SV), wherein an excitation of a fluorophore (FL) on the strand (MS) by the excitation focus (EF) results in a fluorescence response (FR) when the excitation focus (EF) coincides with the fluorophore (FL); - providing a depletion beam (DB) having a depletion focus (DF) with a depletion profile coinciding with the excitation profile of the excitation focus (EF) and causing stimulated emission depletion (STED) of the excitation of the fluorophore (FL) according to the depletion profile; - scanning the coinciding profiles of the excitation focus (EF) and depletion focus (DF) in the sample volume (SV) along a one dimensional scanning line (SL); - trapping an end of the strand (MS) in the sample volume (SV) and extending the strand (MS) along a one-dimensional trapping line (LL) parallel to the scanning line (SL); - aligning the trapping line (LL) to coincide with the scanning line (SL) to have the coinciding profiles of the scanning excitation focus (EF) and depletion focus (DF) coincide with the strand (MS); and - recording the fluorescence response (FR) as a function of a plurality of distinct scanning positions (XO) of the excitation focus (EF) along the scanning line (SL).