QCORE Seminar Series · October 29, 2025
Featuring Anja Kunze, Ph.D.
📄 Access the full slide deck (PDF)
Why We Hosted This Talk
At QCORE, we aim to highlight research that expands how measurement itself is done—especially in areas where existing tools struggle to match the complexity of the systems being studied. Neurobiology is one such area, where critical processes unfold at spatial and temporal scales that are difficult to observe without disrupting the system.
In this seminar, Anja Kunze presented an approach that brings quantum-enabled sensing directly into biological environments. Her work explores how magnetic nanoparticles can function as nano-scale quantum sensors, opening new possibilities for observing neural and cellular processes that are otherwise inaccessible using conventional techniques.
About the Speaker
Anja Kunze, Ph.D.
Anja Kunze, Ph.D. works at the intersection of neurobiology, nanotechnology, and quantum sensing. Her research focuses on designing nanoscale magnetic materials that can function as highly sensitive probes inside complex biological environments. By combining materials engineering with measurement science, her work aims to expand how researchers observe neural and cellular processes—particularly in contexts where conventional electrical or optical tools are limited.
Opening the Talk: The Measurement Challenge in Neurobiology
Anja begins by framing the fundamental problem that motivates this work: many of the most important biological signals occur at scales that are difficult to access with existing tools. Neural systems rely on electrical, chemical, and mechanical interactions that unfold at the level of molecules and cells, yet traditional probes often force a compromise between resolution and invasiveness.
She explains that electrodes offer strong temporal resolution but physically disturb tissue, while optical approaches face limitations related to scattering, phototoxicity, and labeling. This mismatch between the scale of biological processes and the scale of observation, introduced early in the presentation, sets the stage for why new sensing paradigms are needed (slides 1–2).
Why Nanoparticles Offer a Natural Interface
Nanoparticles occupy a size regime that aligns naturally with biological structures. Their dimensions are comparable to cellular components, allowing them to interact locally without disrupting large-scale biological function. At the same time, their physical properties can be engineered with high precision.
Magnetic nanoparticles are particularly well suited to biological environments because magnetic fields penetrate tissue with minimal attenuation and do not require direct electrical contact. Unlike optical probes, magnetic sensing does not depend on line-of-sight and avoids introducing strong electromagnetic fields that could interfere with biological processes. These advantages were illustrated through examples showing how magnetic behavior remains detectable even in crowded, heterogeneous environments (slides 3–4).
Why Nanoparticles Are a Natural Interface
Anja then turns to nanoparticles as a potential bridge between physics and biology. She explains that nanoparticles occupy a size regime comparable to biological structures, allowing them to interact locally without imposing large-scale disruption.
She emphasizes that magnetic nanoparticles are especially well suited to biological environments. Magnetic fields penetrate tissue with minimal attenuation and do not require direct electrical contact or optical access. Unlike light-based probes, magnetic sensing does not depend on line-of-sight and avoids introducing strong electromagnetic fields that could interfere with biological function. These advantages are illustrated through examples discussed in the early part of the talk (slides 3–4).
From Passive Labels to Quantum Sensors
Moving deeper into the physics, Anja explains that at sufficiently small scales, magnetic behavior is governed not only by classical effects but also by quantum properties such as spin states and coherence. By engineering these properties, magnetic nanoparticles can transition from passive labels into active quantum sensors.
She describes how the quantum state of a nanoparticle can encode information about its immediate environment, allowing it to respond sensitively to changes in local magnetic fields, temperature, or mechanical forces. This shift—from labeling to sensing—is a central conceptual move in the work and is illustrated through examples of quantum-sensitive magnetic behavior (slides 5–6).
How Magnetic Nanoparticles Sense Biological Activity
Anja then explains how these sensors interact with biological systems in practice. Neural activity, for example, generates small magnetic fields associated with ionic currents. These fields influence the magnetic response of nearby nanoparticles.
She describes how changes in the particle’s magnetic state can be detected using external readout techniques, rather than direct electrical connections. This enables non-invasive measurements even when sensors are embedded deep within tissue or localized inside cells. She also emphasizes that sensitivity improves as particle size decreases, making nanoscale dimensions a functional advantage rather than a limitation (slides 7–9).
Designing for Biological Compatibility
A major portion of the talk focuses on biological compatibility. Anja stresses that nanoparticle design must account for chemical stability, toxicity, and performance in warm, aqueous, and chemically complex environments.
She discusses surface functionalization strategies that allow nanoparticles to bind selectively to specific cell types or intracellular regions. These surface treatments also help stabilize magnetic properties and prevent aggregation, improving both sensor reliability and biological safety. Several examples illustrate how targeting and stability are achieved simultaneously (slides 10–12).
Applications in Neurobiology
Anja then addresses one of the central challenges of the approach: interpretation. Biological systems are noisy, heterogeneous, and dynamic, and signals detected by nanoparticle sensors may reflect multiple overlapping processes.
She emphasizes the importance of calibration, experimental controls, and complementary measurements. Quantum sensitivity increases access to weak signals, but meaningful interpretation still depends on careful experimental design. Examples discussed at this stage highlight how signal context is essential for drawing reliable conclusions (slides 16–17).
Validation and Experimental Reliability
A substantial portion of the talk is devoted to validation. Anja explains how control experiments are used to distinguish genuine biological signals from background noise, environmental fluctuations, or sensor drift.
She discusses reproducibility across samples, sensitivity limits, and methods for assessing signal stability over time. Validation, she emphasizes, is not a single checkpoint but an iterative process that evolves alongside sensor design and experimental refinement (slides 18–24).
Targeting, Localization, and Specificity
Anja then returns to the importance of knowing where a signal originates. She explains how chemical functionalization enables nanoparticles to be targeted to specific cells, membranes, or intracellular locations.
She emphasizes that localization is critical for interpretability: improved targeting reduces ambiguity and allows signals to be understood within well-defined biological contexts. Several examples illustrate how targeting strategies enhance both biological relevance and measurement clarity (slides 25–30).
Limitations, Tradeoffs, and Open Questions
Rather than presenting the approach as complete, Anja explicitly addresses its limitations. She discusses how increasing sensitivity can introduce new sources of noise, and how densely packed biological environments complicate interpretation.
She frames these tradeoffs as guides for future development, emphasizing that understanding where the technique struggles is essential for determining where it can be most effectively applied (slides 31–34).
Closing the Talk: Looking Ahead
In the final portion of the seminar, Anja looks toward future directions. She outlines potential integrations with other measurement modalities, expanded applications beyond neurobiology, and ongoing improvements in nanoparticle design.
She concludes by emphasizing that the goal is not a single universal sensor, but a toolkit of nanoscale probes that can be tailored to specific biological questions. Magnetic nanoparticles as nano-quantum sensors, she notes, represent a growing platform rather than a finished solution (slides 35–38).
Q&A Highlights
Q1 — How do magnetic nanoparticle sensors compare to traditional electrical probes?
A: Anja explains that magnetic fields interact weakly with biological tissue, enabling measurements without direct electrical contact and with reduced invasiveness.
Q2 — Are quantum sensors too fragile for biological environments?
A: She clarifies that while some quantum systems require extreme isolation, magnetic nanoparticles can be engineered to operate robustly at physiological temperatures.
Q3 — How can meaningful biological signals be separated from background noise?
A: Through careful calibration, controls, and complementary measurements that place quantum sensitivity within a broader experimental framework.
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