Enzyme loaded Multiple Coacervate Emulsions: Towards all aqueous Self-powered Janus Droplets

• Grant number: 24/14333-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2025
• End date: December 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Watson Loh
• Grantee: Adrià Pérez Calm
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 21/12071-6 - Tailoring colloids through supramolecular interactions: from fundamentals to applications, AP.TEM

Abstract

This project aims to prepare all-aqueous multiple coacervate emulsions containing poly(allylamine hydrochloride)/polyacrylic acid (PAH/PAA) and poly(diallyldimethyl ammonium chloride)/polyacrylic acid (PDDA/PAA) coacervates, featuring Janus droplets. We also plan to selectively load enzymes (urease, catalase and glucose oxidase) within one phase of the Janus droplets, evaluating them as all-aqueous micromotor devices. We will study how changes in system composition affects emulsion morphology, such as adding a nonionic polymer to the continuous phase, changing the polycation ratios and the total coacervate concentration or modifying pH and salt concentration. Additionally, we aim to increase emulsion stability by adding particles, like chitin nanocrystals, starch platelets, protein microgels or polystyrene spheres. The hydrophilicity of the particles can be tuned through surface functionalization or protein adsorption. Afterwards, we will measure the binding constants of the selected enzymes with the coacervates with isothermal titration calorimetry (ITC) and determine the encapsulation efficiency and partition coefficient of the enzymes in Janus droplets within the multiple emulsion. We expect to correlate the binding constants calculated for each enzyme with each coacervate with the encapsulation efficiency and partition coefficient. Finally, we will evaluate these Janus droplets as micromotor devices, measuring the trajectory and mean square displacement of droplets in the presence of substrates for the enzyme reaction (urea, glucose, H2O2). We aim to explore the potential of these systems as biosensor devices, correlating the diffusion coefficient of enzyme-loaded Janus droplets with substrate concentration. Monodisperse Janus coacervate droplets will be prepared using microfluidics.