SPR Imaging Gas Phase Detection Small Biological Objects
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Solution Overview
Problem
Existing surface plasmon resonance imaging (SPRi) detection systems face challenges in detecting small biological objects due to limitations in spatial resolution and sensitivity, particularly when the objects have refractive indices close to the carrier liquid and sizes smaller than the detection system's resolution.
Innovation Solution
A detection method involving exposure to a gas phase after sample interaction, followed by image acquisition, which enhances the contrast and visibility of small biological objects by utilizing a standard SPRi system with gas mode configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SPRi detection is performed in liquid phase with standard spatial resolution, then the detection system can operate with conventional optics, but small biological objects (size < spatial resolution) cannot be detected due to insufficient contrast and resolution
Solution Approach 1:
The patent changes the physical state parameter of the medium from liquid to gas phase. By evaporating the liquid carrier and maintaining objects in gas phase, the refractive index difference between objects and surrounding medium increases dramatically, enhancing SPR signal contrast and enabling detection of objects smaller than the spatial resolution limit without modifying the optical system
Solution Approach 2:
The patent utilizes phase transition of the carrier medium from liquid to gas through evaporation. This phase change transforms the detection environment, allowing objects to be detected in gas phase where the refractive index contrast with the surrounding medium is much higher than in liquid phase, thereby improving detection sensitivity for small objects
2Measurement precision
If the carrier liquid is evaporated to improve object visibility, then the refractive index difference increases and object contrast improves, but the objects may be lost or degraded during evaporation
Solution Approach 1:
The patent performs preliminary action by depositing objects onto a solid substrate before evaporation. This ensures objects are firmly anchored to the substrate surface prior to the phase transition, preventing loss during evaporation while maintaining their position for subsequent detection
Solution Approach 2:
The solid substrate acts as an intermediary between the objects and the gas phase environment. It provides mechanical support and anchoring for objects during evaporation, while allowing SPR detection to occur through the substrate. The substrate mediates the interaction between objects and the changing environment, ensuring object retention throughout the process
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
Enables the detection and counting of small biological objects, even when their size is significantly less than the system's spatial resolution, by increasing the reflectivity difference and contrast through the gas phase exposure and image acquisition process.
Implementation Method 1
Surface plasmon resonance occurs when a light signal illuminates a metal-dielectric interface under certain conditions of wavelength, polarization, and angle of incidence. When the conditions are met, the free electrons on the surface of the metal layer absorb the incident photons and convert them into surface plasmon waves.
Implementation Method 2
Surface Plasmon Resonance Imaging, in English), which has the advantage of being a so-called marker-free detection technique (label free, in English) where biological objects are not 'marked' beforehand by a revealing agent.
Implementation Method 3
These plasmon resonance conditions depend in particular on the refractive index at the surface of the metal layer. Thus, when an adsorption/desorption interaction occurs between a ligand and an analyte, the refractive index changes and the plasmon resonance conditions are modified.
Data Source
Figure 1A~1E
Figure 2~3B
Figure 4A~4D
AI summary
The invention relates to a method for detecting biological objects by means of an SPR imaging detection system (1) comprising an optical measurement device (10) configured to generate plasmon resonance on a functionalised surface (5) when said surface is exposed to a gas; the method comprising: • an assimilation step by exposing the functionalised surface (5) to a sample of interest formed of an aqueous carrier liquid containing the biological objects; • a step of removing the liquid in contact with the functionalised surface (5) and exposing the surface to a gas not containing the biological objects, said objects remaining bound to the ligands of the sensitive site of the functionalised surface (5); • a step of acquiring an image of the sensitive site; • a step of detecting the biological objects from the acquired image.