# New Classes of Electron Paramagnetic Resonance Imaging Probes With High-Spin Metal Complexes

> **NIH NIH R35** · COLORADO STATE UNIVERSITY · 2023 · $1

## Abstract

Project Summary/Abstract
The focus of the Zadrozny laboratory is the design of metal complexes for noninvasive sensing
of physiological chemistry. The broader goal of the effort is to make molecular probes that
overcome inherent challenges in electron paramagnetic resonance imaging (EPRI), the unpaired
electron analog to conventional 1H MRI. EPRI can sense local chemistry and could produce
comprehensive chemical and anatomical maps of the body if merged with 1H MRI. Modern EPRI
molecular imaging probes are organic radicals which require dangerous high-energy microwaves
for use in the large magnetic field of an MRI scanner. Hence, the two techniques remain
disconnected. For EPRI to enable imaging of physiological chemistry by integration with MRI, new
probes must be developed to avoid high frequency microwaves at high magnetic fields. The next
five years of the Zadrozny lab’s work involve exploring high-spin metal complexes as an
alternative platform to radicals for molecular probes in EPRI. A key inherent advantage of metal
ions is that the unique electronic feature of large zero-field splitting enables the possibility of safe,
low-frequency microwave use at high magnetic field. Hence, metal complexes with this feature
could provide a completely new set of EPRI molecular imaging probes with capabilities
unmatched by organic radicals. However, all of the basic EPR spectral properties of metal
complexes with low frequency microwaves are unmapped. The Zadrozny lab will amend this
knowledge gap. The work will use synthetic inorganic chemistry and spectroscopic analyses to
(1) understand how to target the frequency/field of the resonance to match the magnetic fields of
MRI scanners with low-frequency microwaves (2) understand how to control the linewidth of the
low-frequency EPR resonances to enhance resolution, and (3) how to merge radical/metal
chemistry in hybrid molecules to gain the advantages of both metals and radicals for a single
molecular probe system. Meeting these objectives will provide a new class of imaging probe
capable of mapping physiological chemistry in a conventional MRI scanner.

## Key facts

- **NIH application ID:** 10712009
- **Project number:** 1R35GM150894-01
- **Recipient organization:** COLORADO STATE UNIVERSITY
- **Principal Investigator:** Joseph M Zadrozny
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $1
- **Award type:** 1
- **Project period:** 2023-09-01 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10712009

## Citation

> US National Institutes of Health, RePORTER application 10712009, New Classes of Electron Paramagnetic Resonance Imaging Probes With High-Spin Metal Complexes (1R35GM150894-01). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/10712009. Licensed CC0.

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