# A New Approach for On-Chip Production of Biological Microgels Using Photochemical Cross-Linking

## TL;DR

This paper introduces a new microfluidic method for making biological microgels using visible light instead of harmful UV light, enabling safer and more versatile biomedical applications.

## Contribution

A visible light-driven microfluidic workflow for producing protein-based microgels with controllable dimensions.

## Key findings

- Microgels were successfully created from Bovine Serum Albumin using [Ru(bpy)3]2+ mediated cross-linking.
- Controllable and uniform microgel dimensions were achieved by adjusting flow rates and reaction times.
- The method is applicable to a wide range of proteins with biological and responsive properties.

## Abstract

Photochemical cross-linking is a
key step for manufacturing microgels
in numerous applications, including drug delivery, tissue engineering,
material production, and wound healing. Existing photochemical cross-linking
techniques in microfluidic devices rely on UV curing, which can cause
cell and DNA damage. We address this challenge by developing a microfluidic
workflow for producing microgels using visible light-driven photochemical
cross-linking of aqueous droplets dispersed in a continuous oil phase.
We report a proof-of-concept to construct microgels from the protein
Bovine Serum Albumin (BSA) with [Ru(bpy)3]2+ mediated cross-linking. By controlling the capillary number of the
continuous and dispersed phases, the volumetric flow rate, and the
photochemical reaction time within the microfluidic tubing, we demonstrate
the construction of protein microgels with controllable and uniform
dimensions. Our technique can, in principle, be applied to a wide
range of different proteins with biological and responsive properties.
This work therefore bridges the gap between hydrogel manufacturing
using visible light and microfluidic microgel templating, facilitating
numerous biomedical applications.