Real-time optical in-vivo thermo-viscoelastometry of albumen and blood vessels in chicken embryo models under laser heating and ablation

The laser ablation technique is commonly used in biomedicine to treat tumor cancerous tissues with minimal invasiveness to surrounding normal tissues. However, an accurate non-contact, real-time, in-situ, label-free thermomechanical measurement of affected tissues undergoing laser heating and ablation is virtually non-existent in clinical settings. In this work, we demonstrate real-time monitoring of local temperature and viscoelastic response of the albumen and blood vessels in chick chorioallantoic membrane (CAM) models during infrared laser heating and ablation by non-contact, label-free Brillouin light scattering (BLS) spectroscopy and fiber Bragg grating (FBG)-based thermal mapping. The albumen and CAM models were selected as ethical and cost-effective models with an easily accessible vasculature network to investigate changes in thermal and viscoelastic properties during laser-induced heating and ablation. Both studied biomaterials became stiffer and less viscous during laser-induced heating due to the thermal denaturation of proteins, forming cross-links with subsequent gelation (coagulation) and water evaporation (dehydration). Demonstrated hybrid BLS-FBG modality has a strong potential to equip conventional laser ablation therapy with accurate, real-time thermomechanical property-informed diagnostics to substantially improve patient outcomes.