Protease-Activated NIR Imaging Agents for In Vivo Detection
Solution Overview
Problem
Current methods for monitoring drug efficacy in vivo are invasive, costly, and lack real-time sensitivity, with peptide-based molecular beacons facing challenges such as instability and nonspecific activation when used for systemic administration.
Innovation Solution
Development of near-infrared fluorophore-based imaging agents with enzymatically cleavable oligopeptides and polyethylene glycol (PEG) or targeting ligands, which are selectively activated by proteases, allowing for real-time imaging of protease expression and disease diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If peptide-based molecular beacons are used for in vivo imaging, then protease activity can be detected with high sensitivity, but the agents suffer from inherent instability and short half-life
Solution Approach 1:
The patent combines a fluorophore, quencher, and protease-cleavable peptide into a single molecular beacon construct. This composite structure remains optically silent until protease cleavage activates fluorescence, providing both high detection sensitivity and improved in vivo stability through the integrated design
Solution Approach 2:
The molecular beacon acts as an intermediary between the protease enzyme and the detection system. The peptide sequence serves as a specific substrate that mediates the interaction, allowing selective detection of target proteases while the fluorophore-quencher system mediates the signal transduction
2Measurement precision
If conventional molecular beacon constructs are used as in vivo imaging agents, then NIR fluorescence can be generated upon protease activation, but long activation time and nonspecific activation occur
Solution Approach 1:
The patent optimizes specific local properties of the molecular beacon including the fluorophore selection (NIR dyes), quencher type, and peptide sequence composition to achieve rapid and specific protease activation. Each component is selected and positioned to maximize local interaction efficiency with the target protease
Solution Approach 2:
The patent modifies key parameters of the molecular beacon construct including fluorophore-quencher distance, peptide sequence length and composition, and chemical structure of the linkage groups to optimize activation kinetics and reduce nonspecific activation while maintaining detection specificity
3Adaptability or versatility
If imaging agents are administered systemically, then whole-body imaging is possible, but nonsspecific activation and reduced target-to-background ratio occur
Solution Approach 1:
The patent extracts and optimizes the essential functional components (fluorophore, quencher, peptide substrate) while removing or minimizing elements that cause nonspecific activation. The design focuses on the core protease-substrate interaction mechanism to achieve specific activation only at the target site
Solution Approach 2:
Instead of trying to prevent nonspecific activation through complex stabilization, the patent inverts the approach by designing the agent to be inherently stable and only activatable through specific protease cleavage. The optically silent state is maintained until the specific biochemical event occurs, naturally suppressing background signal
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 imaging agents provide enhanced target-to-background ratios and fast activation, enabling effective visualization of protease activity in tumors and other tissues with improved stability and specificity, facilitating early disease detection and monitoring.
Implementation Method 1
near-infrared fluorophore-based imaging agents
Implementation Method 2
Q is a fluorescence quencher molecule
Implementation Method 3
S is an enzymatically cleavable oligopeptide
Data Source
AI summary
Disclosed are imaging agents having the following Formula I:wherein F is a near infrared fluorophore, S is an enzymatically cleavable oligopeptide, Q is a fluorescence quencher molecule, and M is a moiety selected from the group consisting of PEG or derivative thereof and a targeting ligand, and wherein F, Q and M are linked to separate amino acids of the enzymatically cleavable oligopeptide. Compositions comprising such compounds, as well as methods of use, methods of identifying a cell or a population of cells in vivo expressing a protease of interest, and methods of treating a disease through imaging are also disclosed.