Related Experiment Video
Updated: Jul 17, 2026
10:54
Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry
Published on: February 4, 2017
Design Strategies for Developing Chiral Macrocyclic Chelators as a Diagnostic Tool.
1Department of Chemistry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China.
Accounts of Chemical Research
|July 16, 2026
Summary
Chiral macrocyclic chelators, including modified DOTA, enhance stability and imaging performance for diagnostic and therapeutic applications. These novel designs improve metal complexation, crucial for advanced molecular imaging and radiopharmaceuticals.
Area of Science:
- Coordination Chemistry
- Medicinal Chemistry
- Molecular Imaging
Background:
- Macrocyclic chelators like DOTA are vital for stable metal complexes in molecular imaging (MRI, PET, SPECT).
- Existing DOTA chelators face limitations such as slow radiolabeling and potential in vivo decomplexation.
- Structural modifications, particularly to the macrocyclic ring, are explored to overcome these limitations.
Purpose of the Study:
- To design and synthesize novel macrocyclic chelators with chiral substituents on the macrocyclic ring.
- To investigate the impact of chiral modifications on metal complex stability, regioisomer formation, and imaging properties.
- To develop versatile chiral bifunctional chelators for targeted imaging and therapeutic applications.
Main Methods:
- Synthesized DOTA analogues with symmetrical chiral substituents on the macrocyclic backbone.
- Utilized NMR studies to confirm the prevention of regioisomer interconversion and assess ligand rigidity.
- Developed chiral bifunctional chelators by attaching functionalized pendant arms to chiral macrocycles.
Main Results:
- Chiral substituents on DOTA prevented TSAP/SAP regioisomerization, enhancing coordination stability and preventing dechelation.
- Gd3+ complexes of chiral DOTAs showed enhanced relaxivity compared to achiral DOTA, suitable for MRI.
- Chiral macrocycles of varying ring sizes (NOTA, DETA) were synthesized for 68Ga radiolabeling, influencing metal ion selectivity.
Conclusions:
- Chiral modification of macrocyclic chelators significantly improves their stability and performance in biomedical imaging.
- These novel chiral chelators offer enhanced properties for MRI contrast agents, radiopharmaceuticals, and targeted therapies.
- The design strategy can be extended to different macrocycle sizes, paving the way for new chelator development.
More Related Videos
Related Concept Videos
02:05Prochirality
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
02:30Chirality in Nature
Chirality is the most intriguing yet essential facet of nature, governing life’s biochemical processes and precision. It can be observed from a snail shell pattern in a macroscopic world to an amino acid, the minutest building block of life. Most of the snails around the world have right-coiled shells because of the intrinsic chirality in their genes. All the amino acids present in the human body exist in an enantiomerically pure state, except for glycine - the sole achiral amino acid. The...
02:25Molecules with Multiple Chiral Centers
Molecules that possess multiple chiral centers can afford a large number of stereoisomers. For instance, while some molecules like 2-butanol have one chiral center, defined as a tetrahedral carbon atom with four different substituents attached, several molecules like butane-2,3-diol have multiple chiral centers. A simple formula to predict the number of stereoisomers possible for a molecule with n chiral centers is 2n. However, there can be a lower number where some of the stereoisomers are...
02:30Chirality at Nitrogen, Phosphorus, and Sulfur
Chirality is most prevalent in carbon-based tetrahedral compounds, but this important facet of molecular symmetry extends to sp3-hybridized nitrogen, phosphorus and sulfur centers, including trivalent molecules with lone pairs. Here, the lone pair behaves as a functional group in addition to the other three substituents to form an analogous tetrahedral center that can be chiral.
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...