Facile One Pot Synthesis of Hybrid Core-Shell Silica-Based Sensors for Live Imaging of Dissolved Oxygen and Hypoxia Mapping in 3D cell models

TL;DR

This study presents a simple, cost-effective method for creating biocompatible core-shell silica microsensors that enable real-time 3D imaging of oxygen levels and hypoxia in live cell models, aiding cancer research.

Contribution

Developed a novel one-pot synthesis of hybrid silica microsensors for accurate, stable, and reversible oxygen monitoring in 3D cell cultures and tumor models.

Findings

Sensors demonstrated high sensitivity and reversibility in oxygen detection.

Successful 3D oxygen mapping revealed hypoxia in tumor-like microenvironments.

Sensors remained stable during aging and bleaching tests.

Abstract

Fluorescence imaging allows for non-invasively visualizing and measuring key physiological parameters like pH and dissolved oxygen. In our work, we created two ratiometric fluorescent microsensors designed for accurately tracking dissolved oxygen levels in 3D cell cultures. We developed a simple and cost-effective method to produce hybrid core-shell silica microparticles that are biocompatible and versatile. These sensors incorporate oxygen-sensitive probes (Ru(dpp) or PtOEP) and reference dyes (RBITC or A647 NHS-Ester). SEM analysis confirmed efficient loading and distribution of the sensing dye on the outer shell. Fluorimetric and CLSM tests demonstrated the sensors' reversibility and high sensitivity to oxygen, even when integrated into 3D scaffolds. Aging and bleaching experiments validated the stability of our hybrid core-shell silica microsensors for 3D monitoring. The Ru(dpp)-RBITC microparticles showed the most promising performance, especially in a pancreatic cancer model using alginate microgels. By employing computational segmentation, we generated 3D oxygen maps during live cell imaging, revealing oxygen gradients in the extracellular matrix and indicating a significant decrease in oxygen levels characteristic of solid tumors. Notably, after 12 hours, the oxygen concentration dropped to a hypoxic level of PO2 2.7 +/- 0.1%.