# Hybrid Oxygen-Sensing Bio-Scaffolds for 3D Micro-Tissue Models

## TL;DR

Researchers developed 3D bio-scaffolds with built-in oxygen sensors to better control and monitor cell environments in lab-grown tissues.

## Contribution

A new hybrid scaffold design with integrated oxygen-sensing materials for 3D cell culture is introduced.

## Key findings

- Matrigel hybrids with NanO2 and Nano-IR probes outperformed other scaffolds in stability and sensing performance.
- Oxygenation and O2 gradients in cell cultures were successfully monitored using fluorescence and phosphorescence lifetime imaging.
- The hybrid scaffolds showed minimal cytotoxicity and ease of fabrication.

## Abstract

Culturing cells and micro-tissue samples in 3D bio-scaffolding structures is gaining popularity; however, precise control of tissue micro-environment in such systems remains challenging. We describe a family of new hybrid bio-scaffolds with 3D O2-sensing ability, produced by simple means from readily available bio-scaffolding and O2-sensing materials. Three different types of phosphorescent O2-sensing materials—polymeric microparticles (MPs), supramolecular probe MitoXpress and nanoparticulate probes NanO2 and Nano-IR (NPs)—were integrated in Matrigel and agarose scaffolding materials and evaluated. Key working characteristics of such hybrid scaffolds, including heterogeneity, stability, cytotoxicity, optical signals and O2-sensing properties, ease of fabrication and use, were compared. The results show superiority of the Matrigel hybrids with NanO2 and Nano-IR probes. Demonstration experiments were conducted with HCT116 cells and individual spheroids derived from these cells, culturing them in the Matrigel–NP hybrid scaffolds and monitoring oxygenation and local O2 gradients on a time-resolved fluorescence plate reader and by phosphorescence lifetime imaging microscopy (PLIM).