Nanoemulsion-induced enzymatic crosslinking of tyramine-functionalized polymer droplets

Abstract

Nanoemulsion-induced enzymatic crosslinking of tyramine-functionalized polymer dropletsKamperman Important noteTo cite this publication, please use the final published version (if applicable). Please check the document version above. CopyrightOther than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons. Takedown policyPlease contact us and provide details if you believe this document breaches copyrights. We will remove access to the work immediately and investigate your claim. AbstractIn situ gelation of water-in-oil polymer emulsions is a key method to produce hydrogel particles.Although this approach is in principle ideal for encapsulating bioactive components such as cells, the oil phase can interfere with straightforward presentation of crosslinker molecules. Several approaches have been developed to induce in-emulsion gelation by exploiting the triggered generation or release of crosslinker molecules. However, these methods typically rely on photo-or acid-based reactions that are detrimental to cell survival and functioning. In this work, we demonstrate the diffusion-based supplementation of small molecules for the in-emulsion gelation of multiple tyramine-functionalized polymers via enzymatic crosslinking using a H2O2/oil nanoemulsion. This strategy is compatible with various emulsification techniques, thereby readily supporting the formation of monodisperse hydrogel particles spanning multiple length scales ranging from the nano-to the millimeter. As proof of principle, we leveraged droplet microfluidics in combination with the cytocompatible nature of enzymatic crosslinking to engineer hollow cellladen hydrogel microcapsules that support the formation of viable and functional 3D microtissues.The straightforward, universal, and cytocompatible nature of nanoemulsion-induced enzymatic crosslinking facilitates its rapid and widespread use in numerous food, pharma, and life science applications.

Single-Cell Microgels: Technology, Challenges, and Applications

“…Opportunely, emulsified hydrogel precursor droplet can be stabilized with surfactants, so that a range of relatively slow (seconds to minutes) gelation mechanisms can be used including photocrosslinking [11], thermal gelation [35], enzymatic crosslinking [36], and Michael-type addition [37] reactions. However, despite the use of surfactants, cell-laden emulsions are prone to rapid destabilization due to the adsorption of biomolecules and cells onto the water-oil interface of the droplets, which limits the time needed for most in situ crosslinking mechanisms.…”

Horseradish Peroxidase Catalyzed Hydrogelation for Biomedical, Biopharmaceutical, and Biofabrication Applications

“…[75] Based on this method, cell-laden microparticles of around 100 mmindiameter have been prepared from avariety of polymer-Ph derivatives, fore xample, gelatin-, CMC-, HA-, dex-tran-, and PEG-Ph. [76] The oil containing H 2 O 2 can be obtained by mixingoil andanaqueoussolution of H 2 O 2 in ahomogenizer,r esulting in an H 2 O 2 /oil nanoemulsion.C ell-laden microcapsules (with hollow cores) are obtained by using the same system,b ut by adding catalaset ot he cell-suspending polymer-Ph solution containing HRP. [77] Catalase catalyzes the decomposition of H 2 O 2 into water and oxygen.…”

Crosslinking Strategies for Microfluidic Production of Microgels

“…H2O2 penetrates inside droplets and triggers HRP-catalyzed crosslinking of Alg-Tyr via C-C and C-O bonding of phenol moieties [65]. H2O2 can also be supplied from W/O nanoemulsion composed of nanodroplets of H2O2 solution dispersed in oil [68]. Dextran-tyramine (Dex-Tyr) conjugates can be prepared by activating hydroxyl groups of dextran with p-nitrophenyl chloroformate (PNC) and reacting the obtained Dex-PNC with tyramine, as shown in Fig.…”