Sessile Droplet Biosensor for Edge-Concentrated EV Detection
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Solution Overview
Problem
Existing methods for detecting extracellular vesicles (EVs) in biological samples face challenges due to interference from non-target substances, leading to longer analysis times and decreased target concentration, especially when subjected to dilution, making rapid diagnosis difficult.
Innovation Solution
A sessile droplet biosensor utilizing a substrate with patterns and bioreceptors, where EVs are stained and form a sessile droplet with a specific contact angle, inducing an internal flow that concentrates EVs at the droplet edge for high-sensitivity detection through binding to bioreceptors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If blood is diluted to rule out interference from non-target substances, then interference is reduced, but target concentration decreases making analysis challenging
Solution Approach 1:
The detection process is segmented into two independent stages: first, whole blood is diluted to reduce interference from non-target substances; second, the target EVs are selectively concentrated at the droplet edge through capillary flow. This segmentation allows both dilution (for reduced interference) and concentration (for maintained detectability) to occur in different spatial and temporal contexts
Solution Approach 2:
The sessile droplet interface acts as an intermediary mechanism that enables selective concentration. The hydrophobic pattern on the substrate creates capillary flow that selectively transports EVs to the droplet edge, serving as a mediator between the diluted sample and the detection bioreceptors, thus recovering target concentration without reversing the dilution
2Object-affected harmful factors
If ultracentrifugation or ExoQuick is used to purify EVs, then interference from non-target substances is removed, but analysis time increases
Solution Approach 1:
The patent replaces complex mechanical purification systems (ultracentrifugation equipment, ExoQuick chemical processing) with a simple capillary flow system based on surface tension and hydrophobic patterns. The sessile droplet configuration creates automatic capillary flow that concentrates EVs without requiring external mechanical forces or chemical additives, thus eliminating time-consuming purification steps while achieving equivalent interference removal
Solution Approach 2:
The detection system performs self-service concentration through the inherent capillary flow generated by the hydrophobic pattern on the substrate. When a droplet is placed on the patterned surface, the contact angle difference automatically drives liquid flow toward the droplet edge, concentrating EVs without external intervention. This self-service mechanism eliminates the need for time-consuming manual purification operations
3Measurement precision
If sample preparation processes are used to purify EVs, then diagnostic accuracy is improved, but rapid diagnosis becomes challenging
Solution Approach 1:
The bioreceptors are pre-immobilized on the hydrophobic pattern before sample application. When the diluted blood sample forms a sessile droplet, the pre-positioned bioreceptors immediately capture EVs as they are concentrated by capillary flow, eliminating the need for post-dilution preparation steps. This preliminary positioning of detection elements enables rapid diagnosis while maintaining diagnostic accuracy
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
The biosensor enables high-sensitivity detection of EVs by concentrating them at the droplet edge, allowing for rapid and accurate analysis of EVs even in diluted samples, facilitating early disease diagnosis and prognosis.
Implementation Method 1
a sessile droplet containing the EVs is formed on the pattern to have a predetermined contact angle with respect to the pattern, and an internal flow of the sessile droplet causes the EVs to migrate to the edge of the sessile droplet
Implementation Method 2
a sessile droplet containing the EVs is formed on the pattern to have a predetermined contact angle with respect to the pattern
Implementation Method 3
a bioreceptor positioned on the pattern and specifically binding to stained EVs
Data Source
AI summary
Proposed are a sessile droplet biosensor and an extracellular vesicle detection method using same, wherein the sessile droplet biosensor can easily and conveniently perform superbright staining of proteins or lipids in extracellular vesicles through a non-specific staining material, such as CFSE, without a complicated signal generation process and can concentrate extracellular vesicles to a high concentration at the edges of sessile droplets by internal flowing induced by non-uniform evaporation in the sessile droplets, thereby detecting extracellular vesicles with high sensitivity. Moreover, the extracellular vesicle detection method using the sessile droplet biosensor can be utilized for standard setting technology for various diseases, such as cancer diagnosis standard setting technology, by the analysis of extracellular vesicle staining signals, or an information providing method for the analysis of extracellular vesicle staining signals can be utilized for early diagnosis of various diseases such as cancer, evaluation of prognosis for treatment, and screening for carcinoma.