Nano-thin walled micro-compartments from transmembrane protein-polymer conjugates.

Area of Science:

• Biomaterials Science
• Colloid and Interface Science
• Polymer Chemistry

Background:

• Protein-polymer conjugates are effective stabilizers for Pickering emulsions.
• Applications include templated micro-compartments, protocells, and drug/gene delivery vehicles.

Purpose of the Study:

• To report, for the first time, the stabilization of Pickering emulsions using conjugates of a genetically modified transmembrane protein, ferric hydroxamate uptake protein component A (FhuA).
• To synthesize and characterize these novel building blocks based on transmembrane proteins (BBTP) for advanced material applications.

Main Methods:

• Genetically modified FhuA (FhuA ΔCVF^tev) was functionalized with an initiator on lysine residues.
• Controlled radical polymerization (CRP) via grafting-from technique was used to attach poly(N-isopropylacrylamide) (PNIPAAm) and poly((2-dimethylamino)ethyl methacrylate) (PDMAEMA).
• Properties like pH/temperature-responsivity and interfacial activity were analyzed using UV-Vis spectrophotometry and pendant drop tensiometry.

Main Results:

• The resulting BBTP conjugates demonstrated significant interfacial activity and formed highly stable Pickering emulsions lasting over a month.
• Synthesized BBTP were used to create micrometer-scale micro-compartments upon UV-induced crosslinking of copolymerized NIPAAm chains.
• Cryo-scanning electron microscopy and scanning force microscopy revealed a stabilizing layer thickness of 11.1 ± 0.6 to 38.0 ± 18.2 nm.

Conclusions:

• Novel protein-polymer conjugates based on FhuA enable the creation of stable Pickering emulsions and functional micro-compartments.
• These micro-compartments hold promise for drug delivery, utilizing the FhuA channel as a gate and smart polymer chains as tunable triggers.