Mannosylated Dextran Chelator Conjugation Without Crosslinking
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Solution Overview
Problem
The current synthesis process for tilmanocept results in significant crosslinking and oligomerization, leading to increased molecular weight variability and polydispersity, which affects its biodistribution and pharmacokinetics, compromising its ability to target CD206-expressing cells effectively.
Innovation Solution
A modified synthesis method that conjugates chelators like DTPA and DOTA to amine dextran precursors using a single activated carboxylic acid group, avoiding crosslinking and oligomerization, resulting in a uniformly monomeric product with improved molecular weight profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional synthesis process is used to conjugate chelators to dextran, then chelator functionality is achieved, but crosslinking and oligomerization occur leading to increased molecular weight variability and polydispersity
Solution Approach 1:
The dextran backbone is pre-modified with amine-leashes bearing mannose moieties before chelator conjugation. This preliminary functionalization ensures that chelators attach only to predetermined sites on the dextran chain, preventing intermolecular crosslinking and oligomerization while maintaining uniform molecular weight distribution
Solution Approach 2:
Amine-leashes serve as intermediary linkers between the dextran backbone and chelators. These leashes provide controlled attachment points that prevent direct dextran-dextran crosslinking, thereby maintaining molecular weight uniformity while enabling chelator functionality
2Manufacturing precision
If crosslinking is avoided during chelator addition, then molecular weight uniformity is maintained, but the challenge of preventing oligomerization increases process complexity
Solution Approach 1:
The dextran is pre-functionalized with amine-leashes before chelator addition. This preliminary step creates controlled reaction sites that inherently prevent crosslinking, simplifying the overall process by eliminating the need for complex crosslinking prevention measures during chelator conjugation
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 method produces tilmanocept with enhanced biodistribution and pharmacokinetic properties, allowing better targeting of CD206-expressing cells and improved imaging sensitivity and accuracy.
Implementation Method 1
conjugates chelators like DTPA and DOTA to amine dextran precursors using a single activated carboxylic acid group
Data Source
AI summary
Disclosed herein is method for conjugating a metal chelating agent to a functionalized dextran by reacting a chelator with an aminated dextran backbone, where the chelator comprises a one, and only one, derivatized carboxylic acid group to form a chelator-dextran complex. In certain aspects, the dextran-chelator complex is substantially free of intra- or intermolecular crosslinking. In certain aspects, the functionalized dextran is an amine dextran, an alkynyl dextran, or a thiol dextran. In exemplary implementations, the functionalized dextran is an amine dextran. In further embodiments, one and only one carboxylic acid group on the chelating agent is derivatized as a N-hydroxysuccinimide (NHS) ester.