Luminescence sensing: a journey through material development and machine learning
Riccardo Marin
Universidad Autonoma de Madrid
Luminescence nanothermometry is a remote sensing technology whereby a temperature readout is obtained by interpreting changes in the emission of luminescent nanomaterials (i.e., nanothermometers). In nanoBIG, our nanothermometers of choice are lanthanide-doped nanoparticles and semiconductor nanocrystals, whose optical properties we tailor for maximum performance in terms of brightness, biocompatibility, and response to temperature. This is what we refer to as upstream action. As of late, we have realized the need to introduce a complementary downstream action. This entails advanced algorithms to analyze the emission spectra or luminescence decay curves whose interpretation yields the thermal readout. Via this approach, we were able to overcome longstanding issues that affect luminescence nanothermometry, like reduced readout precision in situations of low signal level and sensitivity towards multiple parameters.
In this talk, a bird-eye view of the recent advancements we were able to achieve in the field of luminescence nanosensing through the downstream actions. Some of our most recent successes in the implementation of machine learning algorithms to push the boundaries of luminescence nanosensing will be presented, including the achievement of 3D thermal imaging reaching the in vivo level. Future directions of the research in this complex and rewarding field will be discussed.
Luminescence-based sensing of pressure or temperature for biomedical applications: from materials´ development to in vivo proof of concept
Antonio Benayas Hernadez
Universidad Autonoma de Madrid
Luminescence thermometry is a technique that overcomes the limitations affecting other methods (invasiveness; only reporting surface temperature; etc.) aiming to monitor temperature of tissues and organs. That represents a valuable tool for early detection of threatening diseases or tracking heat delivery-based therapies. It is based on the use of luminescent nanothermometers (LNThs); nanoparticles (NPs), proteins, or dyes whose luminescence is strongly temperature-dependent) as remote thermal reporters. However, in vivo luminescence thermometry is hampered by how the presence of biological tissues in the optical path induce spectral distortions that yield inaccurate thermal readouts.
In this work, the robustness of relying on lifetime of the luminescence is evaluated (switching from the spectral to the time domain), through the use of near infrared emitting nanoprobes. After ascertaining the negligible impact of tissue extinction coefficient in the lifetime-based thermal readout, the actual potential of the approach for thermal monitoring of internal organs, in our case the liver, was demonstrated at an in vivo inflammation model.
Aside from temperature, another biomedically relevant knowledge to get is how the mechanical forces control the function of organisms, and mediate the interaction between biological systems and their environments, an insight which can support the development of novel diagnostic and therapeutic procedures. A promising way to overcome the hurdles of invasiveness and lack of versatility plaguing currently applied methods is luminescent manometry. Here, a thorough study is conducted on the manometry performance (pressure-dependent photoluminescence) of CuInS2 quantum dots in the red/near-infrared range. It is shown that tuning size and stoichiometry can simultaneously enhance the CuInS2 QDs’ brightness and response to applied pressure, providing design guidelines on how fundamental parameters assist the quest for better luminescent manometers.
