A sticky situation – simple method for rapid poissonian encapsulation of highly aggregation-prone microbeads in polydisperse emulsions

TL;DR

This paper presents a simple and cost-effective method to improve the distribution of aggregation-prone microbeads in emulsions for high-throughput biomolecule engineering.

Contribution

A novel method using modified pipette tips to restore Poissonian microbead distribution in polydisperse emulsions.

Findings

Modified pipette nozzles effectively disrupt microbead clusters during emulsification.

Emulsions remained stable for weeks at 37°C while maintaining Poissonian microbead distribution.

Two oil-surfactant formulations were successfully used with the new method.

Abstract

Directed evolution leverages the principles of natural selection to engineer biomolecules with desired properties. Microbead-based approaches within water-in-oil emulsions have proven invaluable for high-throughput in vitro selections. However, highly aggregation-prone microbeads present significant challenges, including clustering, inconsistent distribution, and droplet instability. Here, we introduce a simple and cost-effective method for generating polydisperse emulsions with restored Poissonian distributions of highly aggregation-prone microbeads. This approach utilizes modified gel loader pipette tips, drawn out to create nozzles capable of disrupting microbead clusters during emulsification. Two widely utilized oil-surfactant formulations—mineral oil with Abil EM 90 and FluoSurf in HFE 7500 — were evaluated for emulsion preparation. Emulsions prepared using the modified nozzles exhibited exceptional stability, maintaining integrity during week-long incubations at 37°C, and reliably distributed microbeads into droplets in accordance with a Poissonian distribution despite the microbeads’ highly aggregation-prone property.

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