# Focused Electron and X-ray Beam Crosslinking in Liquids for Nanoscale Hydrogels 3D Printing and Encapsulation

## TL;DR

This paper introduces a novel in-liquid electron and X-ray beam technique for 3D printing nanoscale hydrogels, overcoming vacuum incompatibility and enabling advanced tissue engineering and encapsulation applications.

## Contribution

It presents a new method for in-liquid hydrogel crosslinking using ultrathin membranes, allowing direct additive manufacturing with electron and X-ray beams.

## Key findings

- Successful demonstration of in-liquid hydrogel 3D sculpting.
- Validation of the technique through experiments and simulations.
- Potential applications in nanoparticle encapsulation and live-cell fabrication.

## Abstract

Additive fabrication of biocompatible 3D structures out of liquid hydrogel solutions has become pivotal technology for tissue engineering, soft robotics, biosensing, drug delivery, etc. Electron and X-ray lithography are well suited to pattern nanoscopic features out of dry polymers, however, the direct additive manufacturing in hydrogel solutions with these powerful tools is hard to implement due to vacuum incompatibility of hydrated samples. In this work, we resolve this principal impediment and demonstrate a technique for in-liquid hydrogel 3D-sculpturing separating high vacuum instrumentation and volatile sample with ultrathin molecularly impermeable membranes transparent to low-energy electrons and soft X-rays. Using either scanning focused electron or synchrotron soft X-ray beams, the principle of the technique, particularities of the in-liquid crosslinking mechanism and factors affecting the ultimate gel feature size are described and validated through the comparison of experiments and simulations. The potential of this technique is demonstrated on a few practical examples such as encapsulation of nanoparticles and live-cell as well as fabrication of mesoscopic 3D-hydrogel structures via modulation of the beam energy

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Source: https://tomesphere.com/paper/1904.01652