Photomanipulation of Minimal Synthetic Cells: Area Increase, Softening, and Interleaflet Coupling of Membrane Models Doped with Azobenzene‐Lipid Photoswitches

Abstract

Light can effectively interrogate biological systems in a reversible and physiologically compatible manner with high spatiotemporal precision. Understanding the biophysics of photo‐induced processes in bio‐systems is crucial for achieving relevant clinical applications. Employing membranes doped with the photolipid azobenzene‐phosphatidylcholine (azo‐PC), a holistic picture of light‐triggered changes in membrane kinetics, morphology, and material properties obtained from correlative studies on cell‐sized vesicles, Langmuir monolayers, supported lipid bilayers, and molecular dynamics simulations is provided. Light‐induced membrane area increases as high as ≈25% and a ten‐fold decrease in the membrane bending rigidity is observed upon trans‐to‐cis azo‐PC isomerization associated with membrane leaflet coupling and molecular curvature changes. Vesicle electrodeformation measurements and atomic force microscopy reveal that trans azo‐PC bilayers are thicker than palmitoyl‐oleoyl phosphatidylcholine (POPC) bilayers but have higher specific membrane capacitance and dielectric constant suggesting an increased ability to store electric charges across the membrane. Lastly, incubating POPC vesicles with azo‐PC solutions results in the insertion of azo‐PC in the membrane enabling them to become photoresponsive. All these results demonstrate that light can be used to finely manipulate the shape, mechanical and electric properties of photolipid‐doped minimal cell models, and liposomal drug carriers, thus, presenting a promising therapeutic alternative for the repair of cellular disorders.

Photoswitchable endocytosis of biomolecular condensates in giant vesicles

“…This allows the precise measure of the total vesicle area from its geometry, see the Experimental section. Subtracting this initial membrane area from the membrane area under the influence of both UV light and AC field, yields UV-induced area increase of 18±2%, (see Figures S6-S8), which is in good agreement with reported data for slightly different solution conditions [17]. We then compared this expected absolute area increase for individual vesicles wetted by a condensate with the change in apparent area of the vesicles measured directly from the microscopy images as the area sum of the bare vesicle membrane segment and the membrane segment in contact with the condensate (i.e.…”

“…Giant vesicles are cell-sized, biomembrane compartments with increasingly broad spectrum of applications [15], and glycinin is a well-studied storage protein from the soybean that constitutes a robust model for protein condensation [16]. UV exposure of GUVs composed of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) and a photoswitchable azobenzene phospholipid analog (azo-PC) can trigger reversible increase in membrane area upon trans-to-cis isomerization [17]. This suggests that light can finely manipulate the properties of photolipid-doped cell models and liposomal drug carriers, offering potential therapeutic applications for addressing cellular disorders.…”

Membrane Tension Inhibits Lipid Mixing by Increasing the Hemifusion Stalk Energy

“…A very recent development is the optical control of the membrane area using photoswitchable lipids. 54,55 However, micropipette aspiration is a well-established method that allows direct control over tension. 52 We validated our method by conducting bending rigidity measurements for pure DOPC membranes (SI Appendix B, Figure S2).…”

Photoresponsive Azobenzene Nanocluster-Modified Liposomes: Mechanism Analysis Combining Experiments and Simulations

“…17 The conformational difference of the isomers is subsequently transmitted to the acyl chain, affecting the structure of the phospholipid membrane. 18,19 Based on the above theory, a number of classical photoresponsive lipid compounds have emerged, such as PhoDAG-1, 20,21 azo-PC, 22,23 bis azo-PC, 24 and red-azo-PC. 25 Among them, PhoDAG-1 26 was obtained by acylating the azophenyl fatty acid compound FAAzo-4 27 with 1-O-stearoyl-3-O-triethylsilyl-sn-glycerol, using EDC and DMAP as catalysts.…”

“…Based on the above theory, a number of classical photoresponsive lipid compounds have emerged, such as PhoDAG-1, , azo-PC, , bis azo-PC, and red-azo-PC . Among them, PhoDAG-1 was obtained by acylating the azophenyl fatty acid compound FAAzo-4 with 1- O -stearoyl-3- O -triethylsilyl- sn -glycerol, using EDC and DMAP as catalysts.…”