BioPhotonics Preview for November/December 2025

Multiphoton Microscopy & Neurology

A Deeper Look at Aging/Understanding deep-brain structures is crucial for studying neurovascular dynamics, aging-related changes, and neurodegenerative diseases. However, the conventional tools for investigating this – mouse brain studies utilizing two-photon (2P) microscopy with 900 nm excitation – can’t reach the white matter regions deeper than 1 mm where many critical brain functions occur. To overcome this limitation, researchers have adopted 1280 nm excitation, extending imaging depth to 1.2 mm with improved clarity. Additionally, custom conjugated fluorophores are used to enhance signal specificity by reducing leakage from blood vessels. All this extends the boundaries of deep-brain imaging, delivering more accurate insights into brain function and pathology. This article explores these innovations and their impact on biophotonics-driven imaging.

NIR Spectroscopy & Neurology

Functional near-infrared spectroscopy (fNIRS) is emerging as a portable, non-invasive method for continuous bedside brain monitoring—filling a gap that MRI cannot address. Yet, despite promising early data, fNIRS remains largely unknown to many clinicians and lacks the decades of clinical validation enjoyed by MRI or EEG. Its transition from niche research tool to trusted clinical modality hinges on large, peer-reviewed trials that correlate optical metrics with patient outcomes and align with international standards. This feature will examine the credibility gap, the necessity of evidence-building, and the projects aiming to bridge it. Case studies include the PROMETEUS trial to reduce neuro-disability in preterm infants and the H2020 VASCOVID compact TD-NIRS oximeter. Confirmed interviews with Michele Lacereza and Mauro Buttafava – PIONIRS srl, Milano, Italy. Another case study includes consciousness detection in ICU patients by a team led by Adrian M. Owen, Professor of Cognitive Neuroscience and Imaging, Department of Physiology and Pharmacology and Department of Psychology, Western University. Further potential interviews include: Caterina Formica, Bonino Pulejo Neurology Center; Luca Pollonini and Prof. George Zouridakis, both University of Houston; and Prof. Brian Bedlow of at the Laboratory for NeuroImaging of Coma and Consciousness (NICC) at Massachusetts General Hospital.

Fluorescence Lifetime Imaging & Neurology

Fluorescence Lifetime Imaging Microscopy (FLIM) is emerging as a powerful tool in neurology, offering unique contrast mechanisms based on the intrinsic or extrinsic fluorophore's excited-state lifetime. In surgical guidance, particularly for infiltrative tumors like glioblastoma, FLIM can differentiate tumor margins from healthy brain tissue by detecting subtle metabolic changes or specific biomarker binding with high spatial resolution, potentially improving resection accuracy and patient outcomes. Ongoing clinical research leverages FLIM to investigate neurodegenerative diseases, monitor drug delivery and efficacy at the cellular level, and characterize neuronal activity through lifetime-sensitive probes. Its label-free capabilities and sensitivity to the microenvironment position FLIM as a transformative technology for both intraoperative decision-making and fundamental neurological investigations.

Fiber Optics & Neurology

Originally developed for high-speed communication, optical fibers have proven invaluable in the pursuit and advancement of neuroscience, enabling not just the capture of neuron-specific data in isolation, but the tracking of neural signals and communications throughout the brain. Fiber optics have primarily been used for fiber photometry (measuring neural activity by activating fluorescence from encoded sensors) and optogenetics, the use of light to manipulate activity in specific cells. This time of neural imaging can penetrate far deeper in the brain than two-photon microscopy. Thanks to miniaturization of these optics, microscopies delivering femtosecond pulses via optical fiber can now be implanted on freely moving animals, as well as imbedded in endoscopes. Industry produces fiber optics that have been used for specific research, such as the collection of biomarkers from cerebral spinal fluid in TBI patients, as well as deliver non-invasive spectroscopic measurements during surgery. Fiber optic sensors can also be used to track the movements of voltage indicators from neurons, an ability that could produce breakthroughs in the progression of neurodegenerative diseases. And combined with computational algorithms, these single and multimode fibers have the potential to produce valuable data and insights for both researchers and clinicians.

Brain-Gut Connection

It is undeniable that gut physiology plays a significant role in the development of diseases from inflammatory bowel syndrome to neurodegeneration. In recent years, interest in understanding gut pathophysiology in the context of brain-gut interactions has grown. However, tools to measure the activity of the gut in-vivo and to advance our understanding of the enteric nervous system are generally lacking and would greatly benefit the neurogastroenterology field. Optical technologies like two-photon microscopy specifically with calcium imaging has enabled in-depth understanding of the complex interplay between the enteric neurons and their interaction with other cells, however advances towards in-vivo investigation at the level of organs are limited, slowing down the understanding and development of new diagnostic and treatment solution for the digestive system, being the organ most exposed to our environment and thus having a substantial impact on our health.