Mimicking Cellular Signaling Pathways within Synthetic Multicompartment Vesicles with Triggered Enzyme Activity and Induced Ion Channel Recruitment

Abstract

Subcellular compartmentalization of cells, a defining characteristic of eukaryotes, is fundamental for the fine tuning of internal processes and the responding to external stimuli. Reproducing and controlling such compartmentalized hierarchical organization, responsiveness, and communication is important toward understanding biological systems and applying them to smart materials. Herein, a cellular signal transduction strategy (triggered release from subcompartments) is leveraged to develop responsive, purely artificial, polymeric multicompartment assemblies. Incorporation of responsive nanoparticles-loaded with enzymatic substrate or ion channels-as subcompartments inside micrometersized polymeric vesicles (polymersomes) allowed to conduct bioinspired signaling cascades. Response of these subcompartments to an externally added stimulus is achieved and studied by using confocal laser scanning micro scopy (CLSM) coupled with in situ fluorescence correlation spectroscopy (FCS). Signal triggered activity of an enzymatic reaction is demonstrated in multicompartments through recombination of compartmentalized substrate and enzyme. In parallel, a two-step signaling cascade is achieved by triggering the recruitment of ion channels from inner subcompartments to the vesicles' membrane, inducing ion permeability, mimicking endosome-mediated insertion of internally stored channels. This design shows remarkable versatility, robustness, and controllability, demonstrating that multicompartment polymer-based assemblies offer an ideal scaffold for the development of complex cell-inspired responsive systems for applications in biosensing, catalysis, and medicine.

Biomolecule–polymer hybrid compartments: combining the best of both worlds

“…117 One approach to mimic the cell membrane composition is by incorporating glycopolymers within a polymeric membrane. This has been accomplished elegantly by coupling the hydrophobic PDMS blocks with a hydrophilic heparin block 118 or a glycopolymer block. 119,120 In the case where heparin was used as a mimic for heparan sulphate, small nanometre sized polymersomes 121 or GUVs 118 with exposed heparin on the surface were obtained.…”

“…9). 118 First, Heparin was used as receptor like surface modification and allowed the targeted interaction with protamine. Second, the reaction of a hydrophobic enzyme, immobilized within the membrane of the GUVs, was started on demand by releasing its substrate from the reduction sensitive nanoparticles.…”

Combinatorial Strategy for Studying Biochemical Pathways in Double Emulsion Templated Cell‐Sized Compartments

“…and extremely low, due to severe dilution as a result of the selfassembly processes. [28,29] Double emulsion microfluidics has a significant role to play in the fine control of these parameters (encapsulated content and membrane compositions), coupled with the capability for high-throughput and on-demand generation. [30] However, while double emulsions have been extensively used to form GUVs for programmed release of encapsulated hydrophilic [31][32][33] and/or hydrophobic [31,34] cargos, their capabilities are still undeveloped for the study of enzymatic pathways, where they are expected to have substantial advantages.…”

The rise of bio-inspired polymer compartments responding to pathology-related signals

“…An elegant approach to sense the reductive conditions of the GUV environment was achieved by forming GUVs from a mixture of amphiphilic block copolymers PMOXA-b-PDMS-b-PMOXA and PDMS-b-heparin. 1 The resulting GUV allowed the redox reagent dithiothreitol (DTT) to access the cavity where it disassembled encapsulated nanoparticles loaded with reporter dyes. By encapsulating different nanoparticles, each loaded with a specific biomolecule, inside the GUVs, DTT was able to induce signaling cascades that mimic cell signaling.…”

“…Such catalytic compartments can be further refined by: (i) the co-encapsulation of enzymes that function in tandem provided their activities do not interfere, 177 (ii) the combination of individual, communicating compartments 178 and (iii) engineering multicompartment architectures where small internal compartments loaded with biomolecules act as sensors while the GUV's boundary protects and concentrates them on the inside. 1,225 In this context, mimicking the subcellular compartmentalization of cells and controlling the responsiveness and/or communication inside of an artificial polymer-based architecture are two major goals for the development of new bio-inspired materials with potential application as sensors in biomedicine. The large variety of biomolecules, their specificity and precise functionality support the extension of the sensing ability of such bio-inspired compartments and provide ideal conditions for multiplexed sensing approaches.…”