Cindy Shi

All Publications

• Mechanosensitive Polymer Matrices of Biologically-Relevant Compliance Based on Upconverting Nanoparticles. Advanced materials (Deerfield Beach, Fla.) Shi, C. H., Cano, M. C., Casar, J. R., Moradifar, P., Robinson, B. G., Kaltschmidt, J. A., Goodman, M. B., Dionne, J. A. 2026: e22706

  Abstract

  Upconverting nanoparticles (UCNPs) are promising optical biomechanical force sensors due to their near-infrared excitation, low toxicity, photostability, and linear colorimetric sensitivity to micronewtons of force. Recently, a composite force sensor based on UCNPs embedded in a polystyrene microbead enabled the first real-time measurement of feeding forces in living nematodes. However, the comparatively large stiffness of polystyrene only makes it relevant to biomedical applications in a small subset of biological tissue. To facilitate deployment of UCNPs into biological tissues with a range of mechanical properties, we expand upon polymer-UCNP composite systems by embedding UCNPs in three polymer matrices with varying stiffnesses (epoxy resin, polydimethylsiloxane, and alginate hydrogels). Furthermore, to enhance these composites' mechanosensitivity, we methodically investigate using two different core-shell architectures of SrLuF-based UCNPs doped with ytterbium, erbium, and varying manganese concentrations. We calibrate polymer-UCNP composite optical force sensitivity with colocalized atomic force and confocal microscopy. Using the red to green emission ratio (Δ% IRed:IGreen) as the force read-out, we determine that SrLuF:Yb0.28Er0.025Mn0.013 @ SrYF dispersed in epoxy resin exhibits the greatest emission color change (12 Δ%IRed:IGreen per microNewton). Finally, we map forces in the epoxy-UCNP composite on the macroscale between the joint of a chicken wing bone using a commercially available wide-field microscope, thereby demonstrating its ability to optically measure pressures in situ. This work establishes the utility and modularity of the UCNP-polymer composite system for force-sensing in geometrically and mechanically diverse biological systems.

  View details for DOI 10.1002/adma.202522706

  View details for PubMedID 42007868

• Solution-phase sample-averaged single-particle spectroscopy of quantum emitters with femtosecond resolution. Nature materials Shi, J., Shen, Y., Pan, F., Sun, W., Mangu, A., Shi, C., McKeown-Green, A., Moradifar, P., Bawendi, M. G., Moerner, W. E., Dionne, J. A., Liu, F., Lindenberg, A. M. 2024

  Abstract

  The development of many quantum optical technologies depends on the availability of single quantum emitters with near-perfect coherence. Systematic improvement is limited by a lack of understanding of the microscopic energy flow at the single-emitter level and ultrafast timescales. Here we utilize a combination of fluorescence correlation spectroscopy and ultrafast spectroscopy to capture the sample-averaged dynamics of defects with single-particle sensitivity. We employ this approach to study heterogeneous emitters in two-dimensional hexagonal boron nitride. From milliseconds to nanoseconds, the translational, shelving, rotational and antibunching features are disentangled in time, which quantifies the normalized two-photon emission quantum yield. Leveraging the femtosecond resolution of this technique, we visualize electron-phonon coupling and discover the acceleration of polaronic formation on multi-electron excitation. Corroborated with theory, this translates to the photon fidelity characterization of cascaded emission efficiency and decoherence time. Our work provides a framework for ultrafast spectroscopy in heterogeneous emitters, opening new avenues of extreme-scale characterization for quantum applications.

  View details for DOI 10.1038/s41563-024-01855-7

  View details for PubMedID 38589542

  View details for PubMedCentralID 5615041

• Remotely controlled chemomagnetic modulation of targeted neural circuits. Nature nanotechnology Rao, S. n., Chen, R. n., LaRocca, A. A., Christiansen, M. G., Senko, A. W., Shi, C. H., Chiang, P. H., Varnavides, G. n., Xue, J. n., Zhou, Y. n., Park, S. n., Ding, R. n., Moon, J. n., Feng, G. n., Anikeeva, P. n. 2019

  Abstract

  Connecting neural circuit output to behaviour can be facilitated by the precise chemical manipulation of specific cell populations1,2. Engineered receptors exclusively activated by designer small molecules enable manipulation of specific neural pathways3,4. However, their application to studies of behaviour has thus far been hampered by a trade-off between the low temporal resolution of systemic injection versus the invasiveness of implanted cannulae or infusion pumps2. Here, we developed a remotely controlled chemomagnetic modulation-a nanomaterials-based technique that permits the pharmacological interrogation of targeted neural populations in freely moving subjects. The heat dissipated by magnetic nanoparticles (MNPs) in the presence of alternating magnetic fields (AMFs) triggers small-molecule release from thermally sensitive lipid vesicles with a 20 s latency. Coupled with the chemogenetic activation of engineered receptors, this technique permits the control of specific neurons with temporal and spatial precision. The delivery of chemomagnetic particles to the ventral tegmental area (VTA) allows the remote modulation of motivated behaviour in mice. Furthermore, this chemomagnetic approach activates endogenous circuits by enabling the regulated release of receptor ligands. Applied to an endogenous dopamine receptor D1 (DRD1) agonist in the nucleus accumbens (NAc), a brain area involved in mediating social interactions, chemomagnetic modulation increases sociability in mice. By offering a temporally precise control of specified ligand-receptor interactions in neurons, this approach may facilitate molecular neuroscience studies in behaving organisms.

  View details for DOI 10.1038/s41565-019-0521-z

  View details for PubMedID 31427746