Targeted Fluorescent Nanoparticles for Metastatic Lymph Node Detection
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Solution Overview
Problem
Current imaging methods, such as ultrasound and MRI, struggle to accurately diagnose lymph node metastasis in breast cancer due to issues like contrast agent spillage, partial volume effects, and artifacts, making it difficult to differentiate between benign and malignant lymph nodes.
Innovation Solution
A fluorescent contrast agent with a targeting function is developed, using a nanoformulation material linked by a disulfide bond, which binds specifically to M2 tumor-associated macrophages (TAMs) and emits fluorescence in a tumor microenvironment, allowing for non-invasive imaging of metastatic lymph nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional contrast agents are used in ultrasound and MRI imaging, then imaging can be performed, but the diagnostic precision for lymph node metastasis is insufficient due to contrast agent spillage, partial volume effects, and artifacts
Solution Approach 1:
The patent segments the contrast agent system into multiple functional components: a targeting module (mannose or its derivative) that specifically binds to M2 TAMs, a fluorescent probe module for signal generation, and a disulfide bond linker that provides environment-responsive release. This segmentation allows each module to perform its specific function optimally, with the targeting module ensuring precise localization to metastatic lymph nodes while the fluorescent module provides detectable signals, thereby resolving the contradiction between measurement precision and imaging reliability
Solution Approach 2:
The patent utilizes parameter changes in the tumor microenvironment, specifically the high concentration of reduced glutathione, to trigger disulfide bond cleavage and fluorescent probe release. This parameter-based activation mechanism ensures that the contrast agent remains stable during circulation and imaging but becomes active specifically in the tumor microenvironment, significantly improving diagnostic precision while maintaining imaging reliability through environment-specific activation
2Object-affected harmful factors
If mannose is used as a targeting agent, then biocompatibility and non-toxicity are achieved, but rapid metabolism and clearance occur due to its small molecular size
Solution Approach 1:
The patent constructs a composite contrast agent system where mannose (or its derivative) is conjugated to a fluorescent probe through a disulfide bond linker. This composite structure combines the biocompatibility and targeting specificity of mannose with the imaging capability of the fluorescent probe, while the nanoparticle formulation provides extended circulation time. The composite material approach allows the system to maintain the advantageous properties of mannose while overcoming its rapid clearance through structural integration
Solution Approach 2:
The patent employs a nested structure where the mannose-fluorescent probe conjugate is encapsulated within a nanoparticle formulation. This nested architecture protects the mannose targeting moiety from rapid metabolism while allowing it to remain accessible for binding to M2 TAMs. The nanoparticle core provides structural stability and extended circulation, while the surface-conjugated mannose maintains its biological activity, effectively resolving the contradiction between biocompatibility and retention time
3Stability of the object's composition
If the fluorescent probe is linked through a stable bond, then structural stability is maintained, but the probe cannot be released to emit fluorescence in the tumor microenvironment
Solution Approach 1:
The patent introduces dynamic responsiveness to the contrast agent system by using a disulfide bond linker that can undergo reversible cleavage based on the redox environment. The disulfide bond remains stable under physiological conditions during circulation, maintaining structural integrity, but is selectively cleaved in the high-glutathione environment of the tumor microenvironment. This dynamic behavior allows the system to transition from a stable conjugate to an active fluorescent probe, resolving the contradiction between structural stability and fluorescence detection precision
Solution Approach 2:
The patent exploits parameter changes in the tumor microenvironment, specifically the elevated concentration of reduced glutathione, to trigger selective cleavage of the disulfide bond linker. This parameter-based activation mechanism ensures that the fluorescent probe is released only in the tumor microenvironment where it is needed for precise detection, while the conjugate remains stable during circulation. The parameter change approach allows the system to maintain structural stability while enabling environment-specific probe release for accurate fluorescence detection
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 contrast agent achieves long-term accurate targeting and high specificity and sensitivity in diagnosing metastatic lymph nodes by utilizing a disulfide bond that breaks in a tumor microenvironment, enabling fluorescence differentiation.
Implementation Method 1
utilizing a disulfide bond that breaks in a tumor microenvironment, enabling fluorescence differentiation
Implementation Method 2
emits fluorescence in a tumor microenvironment, allowing for non-invasive imaging of metastatic lymph nodes
Data Source
AI summary
The present disclosure provides a fluorescent contrast agent with a targeting function, and a preparation method and a use thereof, and belongs to the technical fields of nanomaterials and biomedical materials. The fluorescent contrast agent (MR780 NPs) of the present disclosure can specifically bind to CD206 on a surface of tumor-associated macrophages (TAMs). MR780 NPs accumulate in lymph nodes invaded by tumor cells and undergo an oxidation-reduction reaction with reduced glutathione in a tumor microenvironment, which triggers a fluorescence signal of MR780 NPs; and MR780 NPs do not accumulate and do not show fluorescence in normal lymph nodes. Therefore, the fluorescent contrast agent of the present disclosure can be used to diagnose lymph node metastasis (LNM) of breast cancer, realize the preoperative evaluation of LNM, assist in the clinical determination of tumor staging and the formulation of a surgical plan, and achieve the accurate resection under intraoperative fluorescence navigation.