In situ two-photon fluorescence spectroscopy to precisely reveal intracellular lipid droplet microenvironment via a carbonized polymer dot nanosensor

Abstract

Lipid droplets (LDs) are vital dynamic cellular organelles that maintain lipid equilibrium and support biological communication. The polarity of LDs is critical, as their heterogeneity is closely related to pathophysiological developments. To investigate these changes, we developed a polarity-specific two-photon fluorescence (TPF) platform for real-time and precise monitoring of the polarity microenvironment of intracellular LDs with a carbonized polymer dots (CPD) probe. This platform enables the accurate and in situ polarity assessment of a single LD. Using this platform, we identified differences in LD polarity between cancerous and non-cancerous cells, as well as variations in LD polarity during pathophysiological events such as ferroptosis and steatosis. The development of the CPD probe associated with TPF spectroscopy marks a significant advancement in understanding the role of LDs in lipid-associated diseases.