Name: modulating shape of polyester based polymersomes using osmotic pressure
Uploaded: 2021-04-21T15:00:00
Description: Watch this Scientific Journal Video about Modulating Shape of Polyester Based Polymersomes using Osmotic Pressure at JoVE.com

This project was funded in part by the National Institutes of Health Project number 5P20GM103499-19 through the Student Initiated Research Project Program. This work was also partially supported by Clemson&#39;s Creative Inquiry Program. We also acknowledge Nicholas L&#39;Amoreaux and Aon Ali who initially worked on creating this protocol, publishing their first paper cited here14.

1. Spherical polymersome formation using a solvent injection method
<ol>
	<li>Dissolution of polyesters in organic solvent 
	NOTE: Only one polyester should be dissolved in its respective organic solvent at a time to form polymersomes.
	<ol>
		<li>Dissolve polyesters PEG-PLA or PEG-b-poly(lactic-co-glycolic acid) (PEG-PLGA) in dimethyl sulfoxide (DMSO) at a concentration of 1.5% weight. Specifically, dissolve 0.015 g of selected polyester in 1 mL of DMSO (15 mg/mL). Full dissolution of the polymer may require peri...

<ol>
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E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversible+activation+of+pH-sensitive+cell+penetrating+peptides+attached+to+gold+surfaces.">Reversible activation of pH-sensitive cell penetrating peptides attached to gold surfaces.</a> Chemical Communications. 51 (2), 273-275 (2015).</li><li>Zhou, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesoporous+silica+nanoparticles+for+drug+and+gene+delivery.">Mesoporous silica nanoparticles for drug and gene delivery.</a> Acta Pharmaceutica Sinica B. 8 (2), 165-177 (2018).</li><li>Champion, J. A., Mitragotri, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+target+geometry+in+phagocytosis.">Role of target geometry in phagocytosis.</a> Proceedings of the National Academy of Sciences of the United States of America. 103 (13), 4930-4934 (2006).</li><li>Banerjee, A., Qi, J., Gogoi, R., Wong, J., Mitragotri, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+nanoparticle+size,+shape+and+surface+chemistry+in+oral+drug+delivery.">Role of nanoparticle size, shape and surface chemistry in oral drug delivery.</a> Journal of Controlled Release. 238, 176-185 (2016).</li><li>Kolhar, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+shape+effects+to+target+antibody-coated+nanoparticles+to+lung+and+brain+endothelium.">Using shape effects to target antibody-coated nanoparticles to lung and brain endothelium.</a> Proceedings of the National Academy of Sciences. 110 (26), 10753-10758 (2013).</li><li>Meng, F., Zhong, Z., Feijen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stimuli-responsive+polymersomes+for+programmed+drug+delivery.">Stimuli-responsive polymersomes for programmed drug delivery.</a> Biomacromolecules. 10 (2), 197-209 (2009).</li><li>Iqbal, S., Blenner, M., Alexander-Bryant, A., Larsen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymersomes+for+therapeutic+delivery+of+protein+and+nucleic+acid+macromolecules:+from+design+to+therapeutic+applications.">Polymersomes for therapeutic delivery of protein and nucleic acid macromolecules: from design to therapeutic applications.</a> Biomacromolecules. 21 (4), 1327-1350 (2020).</li><li>Discher, D. E., Ahmed, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymersomes.">Polymersomes.</a> Annual review of biomedical engineering. 8, 323-341 (2006).</li><li>Seifert, U., Berndl, K., Lipowsky, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape+transformations+of+vesicles:+Phase+diagram+for+spontaneous-+Curvature+and+bilayer-coupling+models.">Shape transformations of vesicles: Phase diagram for spontaneous- Curvature and bilayer-coupling models.</a> Physical Review A. 44 (2), 1182-1202 (1991).</li><li>Rikken, R. S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shaping+polymersomes+into+predictable+morphologies+via+out-of-equilibrium+self-assembly.">Shaping polymersomes into predictable morphologies via out-of-equilibrium self-assembly.</a> Nature Communications. 7, 1-7 (2016).</li><li>Kim, K. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymersome+stomatocytes:+Controlled+shape+transformation+in+polymer+vesicles.">Polymersome stomatocytes: Controlled shape transformation in polymer vesicles.</a> Journal of the American Chemical Society. 132 (36), 12522-12524 (2010).</li><li>L'Amoreaux, N., Ali, A., Iqbal, S., Larsen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Persistent+prolate+polymersomes+for+enhanced+co-delivery+of+hydrophilic+and+hydrophobic+drugs.">Persistent prolate polymersomes for enhanced co-delivery of hydrophilic and hydrophobic drugs.</a> Nanotechnology. 31 (17), 175103 (2020).</li><li>Salva, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymersome+shape+transformation+at+the+nanoscale.">Polymersome shape transformation at the nanoscale.</a> ACS Nano. 7 (10), 9298-9311 (2013).</li><li>Skoczen, S. L., Stern, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+Nanoparticles+Intended+for+Drug+Delivery.">Characterization of Nanoparticles Intended for Drug Delivery.</a> Methods in Molecular Biology. 1682, (2018).</li><li>Bhattacharjee, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DLS+and+zeta+potential+-+What+they+are+and+what+they+are+not.">DLS and zeta potential - What they are and what they are not.</a> Journal of Controlled Release. 235, 337-351 (2016).</li><li>Men, Y., Li, W., Lebleu, C., Sun, J., Wilson, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tailoring+polymersome+shape+using+the+Hofmeister+effect.">Tailoring polymersome shape using the Hofmeister effect.</a> Biomacromolecules. 21 (1), 89-94 (2020).</li><li>Decuzzi, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Size+and+shape+effects+in+the+biodistribution+of+intravascularly+injected+particles.">Size and shape effects in the biodistribution of intravascularly injected particles.</a> Journal of Controlled Release. 141 (3), 320-327 (2010).</li><li>Liu, Y., Tan, J., Thomas, A., Ou-Yang, D., Muzykantov, V. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+shape+of+things+to+come:+Importance+of+design+in+nanotechnology+for+drug+delivery.">The shape of things to come: Importance of design in nanotechnology for drug delivery.</a> Therapeutic Delivery. 3 (2), 181-194 (2012).</li><li>Tao, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape-specific+polymeric+nanomedicine:+Emerging+opportunities+and+challenges.">Shape-specific polymeric nanomedicine: Emerging opportunities and challenges.</a> Experimental Biology and Medicine. 236 (1), 20-29 (2011).</li><li>L'Amoreaux, N., Ali, A., Iqbal, S., Larsen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Persistent+prolate+polymersomes+for+enhanced+co-delivery+of+hydrophilic+and+hydrophobic+drugs.">Persistent prolate polymersomes for enhanced co-delivery of hydrophilic and hydrophobic drugs.</a> BioRxiv. , 796201 (2019).</li><li>Chandler, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interfaces+and+the+driving+force+of+hydrophobic+assembly.">Interfaces and the driving force of hydrophobic assembly.</a> Nature. 437 (7059), 640-647 (2005).</li><li>Wong, C. K., Mason, A. F., Stenzel, M. H., Thordarson, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+non-spherical+polymersomes+driven+by+hydrophobic+directional+aromatic+perylene+interactions.">Formation of non-spherical polymersomes driven by hydrophobic directional aromatic perylene interactions.</a> Nature Communications. 8 (1), (2017).</li><li>Abdelmohsen, L. K. E. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape+characterization+of+polymersome+morphologies+via+light+scattering+techniques.">Shape characterization of polymersome morphologies via light scattering techniques.</a> Polymer. 107, 445-449 (2016).</li><li>Men, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonequilibrium+Reshaping+of+polymersomes+via+polymer+addition.">Nonequilibrium Reshaping of polymersomes via polymer addition.</a> ACS Nano. 13 (11), 12767-12773 (2019).</li><li>Meeuwissen, S. A., Kim, K. T., Chen, Y., Pochan, D. J., van Hest, J. C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+shape+transformation+of+polymersome+stomatocytes.">Controlled shape transformation of polymersome stomatocytes.</a> Angewandte Chemie. 123 (31), 7208-7211 (2011).</li><li>Wong, C. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Faceted+polymersomes:+A+sphere-to-polyhedron+shape+transformation.">Faceted polymersomes: A sphere-to-polyhedron shape transformation.</a> Chemical Science. 10 (9), 2725-2731 (2019).</li><li>Chidanguro, T., Ghimire, E., Simon, Y. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape-transformation+of+polymersomes+from+glassy+and+crosslinkable+ABA+triblock+copolymers.">Shape-transformation of polymersomes from glassy and crosslinkable ABA triblock copolymers.</a> Journal of Materials Chemistry B. 8 (38), 8914-8924 (2020).</li><li>Van Oers, M. C. M., Rutjes, F. P. J. T., Van Hest, J. C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tubular+polymersomes:+A+cross-linker-induced+shape+transformation.">Tubular polymersomes: A cross-linker-induced shape transformation.</a> Journal of the American Chemical Society. 135 (44), 16308-16311 (2013).</li><li>Che, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathway+dependent+shape-transformation+of+azide-decorated+polymersomes.">Pathway dependent shape-transformation of azide-decorated polymersomes.</a> Chemical Communications. 56 (14), 2127-2130 (2020).</li><li>Haryadi, B. 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Self-assembled systems are notoriously uncontrollable. Their final properties, including size, shape, and structure, are driven by the chosen amphiphile&#39;s hydrophobic properties and the solvent environment selected. Amphiphilic block copolymers tend towards spherical shapes, which minimizes Gibb&#39;s free energy and leads to the thermodynamic equilibrium23, thus forming polymersomes. Because of their equilibrium nature, polymersomes are significantly more challenging to elongate or alter in s...

Shape modulation is a relatively new and efficient way to improve nanoparticle-mediated drug delivery. Not only does the change in morphology increase the surface area of particles, which in turn allows for a greater carrying capacity, but it also has implications across the board to improve stability, circulation time, bioavailability, molecular targeting, and controlled release1. Polymersomes, the nanoparticle of focus in this method, tend to thermodynamically self-assemble into a spherical shape, which has proven to be impractical in cellular uptake and is more easily detected in the immune system as a foreign body. Being able to elongate the structure into a prolate or a rod will allow the drug carrier to evade macrophages by mimicking native cells and more successfully deliver to their desired target2,3,4,5,6,7. The significant benefits of polymersomes, including membrane-bound protection of payloads, stimuli-responsiveness of the membrane, and dual encapsulation of hydrophilic and hydrophobic drugs8,9,10, that make them strong candidates for drug delivery are maintained during shape modulation.
There are many different methods in modulating polymersomes&#39; shapes, and each comes with its respective advantages and disadvantages. However, most of these methods fall into two categories: solvent-driven and salt-driven osmotic pressure change11. Both approaches aim to overcome the bending energy present after polymersomes are formed in a spherical equilibrium shape. By introducing an osmotic pressure gradient, polymersomes can be forced to bend into elongated structures despite strong bending energies11,12.
The solvent-based method explores shape change inspired by the work of Kim and van Hest13. They plasticized polymersomes in an organic solvent and water mixture to trap the organic solvents in the vesicle membrane and drive water out of the vesicle core. Eventually, the particle&#39;s internal volume is so low that it elongates. While this method has shown promise, it lacks practicality. This method requires different solvents for each individual polymeric backbone involved in the modulation. Therefore, it is not widely applicable to promote shape change. Conversely, the salt-based method is uniform and utilizes one universal driver that can introduce osmotic pressure to many block copolymer-based polymersomes.
This project utilizes the salt-based method introduced by L&#39;Amoreaux et al14. This protocol involves two rounds of dialysis. One aims at purifying and solidifying poly(ethylene glycol)-b-poly(lactic acid) (PEG-PLA) polymersomes by removing organic solvent that may have gotten trapped in the bilayer during production, and one that promotes the shape change. The second dialysis step introduces a 50 mM NaCl solution that creates an osmotic pressure gradient to drive the shape change. This method is supported by Salva et al., who note that hypertonic stress in a solution will cause the vesicle to shrink15. This method builds on a previously published method14 looking at two different polyester-based polymersomes and various salt gradients from 50-200 mM NaCl. Polyesters are used due to their biocompatibility and biodegradation. The salt gradient has varying effects on the shape depending on the hydrophobicity of the block copolymer backbone. It can be used to create prolates, rods, and stomatocytes. This salt-driven method was chosen because of the ease of replication and experimental versatility.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>15*45 vials screw thread w/cap attached</td>
			<td>Fisherbrand</td>
			<td>9609104000</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide</td>
			<td>Fisher Chemical</td>
			<td>D128-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide</td>
			<td>BDH</td>
			<td>BDH1115-1LP</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoremp stirrers, hotplates, and stirring hotplates</td>
			<td>Fisher scientific</td>
			<td>CIC00008110V19</td>
			<td></td>
		</tr>
		<tr>
			<td>LEGATO 130 SYRINGE PUMP</td>
			<td>kd Scientific</td>
			<td>788130</td>
			<td></td>
		</tr>
		<tr>
			<td>PEG(1000)-b-PLA(5000), Diblock Polymer</td>
			<td>Polysciences Inc</td>
			<td>24381-1</td>
			<td>note the molecular weights when replicating</td>
		</tr>
		<tr>
			<td>Poly(ethylene glycol) (2000) Methyl ether-block-poly(lactide-co-glycolide) (4500)</td>
			<td>Sigma aldrich</td>
			<td>764825-1G</td>
			<td>note the molecular weights when replicating</td>
		</tr>
		<tr>
			<td>Single-Use Syringe/BD PrecisionGlide Needle combination, sterile, BD medical</td>
			<td>BD medical</td>
			<td>BD305620</td>
			<td>Tuberculin</td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>BDH</td>
			<td>BDH9286</td>
			<td></td>
		</tr>
		<tr>
			<td>Zetasizer Nano ZS</td>
			<td>Malvern</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

modulating shape of polyester based polymersomes using osmotic pressure

Polymersomes are membrane-bound, bilayer vesicles created from amphiphilic block copolymers that can encapsulate both hydrophobic and hydrophilic payloads for drug delivery applications. Despite their promise, polymersomes are limited in application due to their spherical shape, which is not readily taken up by cells, as demonstrated by solid nanoparticle scientists. This article describes a salt-based method for increasing the aspect ratios of spherical poly(ethylene glycol) (PEG)- based polymersomes. This method can elongate polymersomes and ultimately control their final shape by adding sodium chloride in post-formation dialysis. Salt concentration can be varied, as described in this method, based on the hydrophobicity of the block copolymer being used as the base for the polymersome and the target shape. Elongated nanoparticles have the potential to better target the endothelium in larger diameter blood vessels, like veins, where margination is observed. This protocol can expand therapeutic nanoparticle applications by utilizing elongation techniques in tandem with the dual-loading, long-circulating benefits of polymersomes.

Table 2 presents expected results when following the protocol step 1. Note that DMSO is used as a solvent for both PEG-PLA and PEG-PLGA in polymersomes formation. Deviation from this solvent is possible, as other water-miscible solvents will dissolve the copolymers but is expected to change results. It is expected that PDI will be less than 0.2, indicating the formation of monodisperse polymersomes17. Note that increasing hydrophobicity leads to increased deviation in both polymer...

Watch this Scientific Journal Video about Modulating Shape of Polyester Based Polymersomes using Osmotic Pressure at JoVE.com

Modulating Shape of Polyester Based Polymersomes using Osmotic Pressure

Polymersomes are self-assembled polymeric vesicles that are formed in spherical shapes to minimize Gibb's Free Energy. In the case of drug delivery, more elongated structures are beneficial. This protocol establishes methods to create more rod-like polymersomes, with elongated aspect ratios, using salt to induce osmotic pressure and reduce internal vesicle volumes.

Polymersomes are membrane-bound, bilayer vesicles created from amphiphilic block copolymers that can encapsulate both hydrophobic and hydrophilic payloads ...

Nanoparticle shape influences cellular uptake, but limited work has been done to change the shape of polymersomes. This protocol demonstrates how to elongate polymersomes for enhanced drug delivery applications. This technique provides a simple approach that can create many different polymersome shapes with potential applications in drug delivery, pseudo cells, or for other unexplored fields.Elongated polymersomes can simultaneously deliver hydrophobic and hydrophilic drugs and more easily in to the cells. This technique could help shuttle drugs across the blood-brain barrier, addressing a major medical challenge. To begin, dissolve 0.015 grams of selected polyester in one milliliter of DMSO by vortexing for 15 minutes, and set up the solvent injection apparatus.Place the start plate directly below the vertical syringe pump, then place a five milliliter glass bile with one milliliter of type two deionized water in a miniature star bar on the stir plate. Adjust the syringe pumps height to allow for the tip of the needle to be fully immersed in type two deionized water and set the infusion rate of the syringe pump to five microliters per minute. Perform the solvent injection by drawing the organic solvent and polyester solution into a 27 gauge needle.Place the needle into the syringe pump and make sure that it is secure. Adjust the pusher block to touch the syringe plunger's end. Start the stir plate so that the water is spinning at 100 revolutions per minute, and then start the syringe pump.Once the syringe pump has fully infused the organic solvent and polymer into the water, remove the stir bar and cap the glass vile. For characterization of the polymersome via dynamic light scattering or DLS, add one milliliter of water with a small percentage of organic solvent and polymer to a one milliliter cuvette. Performed DLS by placing the cuvette into the system and setting up the run.Read the polymersome intensity weighted diameter and polydispersity index or PDI. After washing a 300 kilodalton dialysis membrane according to protocols provided by the manufacturer, add one milliliter of polymersome solution into the reservoir of the dialysis device. Place the dialysis device in the 250 milliliter beaker with 150 milliliters of type two deionized water on a stir plate.Set the stir plate to a speed that allows for gentle movement of the dialysis device and leave it to stir overnight. After the dialysis has completed, extract the one milliliter polymersome solution from the dialysis device. Create 150 milliliters of desired salt buffer with either 50, 100 or 200 millimolar concentration of sodium chloride based on the final desired polymersome properties and keep the load of dialysis device in 150 milliliters of salt solution for 18 hours for stirring.After shape modulation, perform DLS measurements. Pay particular attention to PDI measurements compared to spiritual polymersomes as a change in PDI suggests an effective shape change in polymersomes. Use appropriate controls for imaging, especially non-shape modulated polymersomes to ensure the method's success.TEM observation of PEG-PLA based polymersomes indicate an overall spherical structure with a thicker exterior line that is indicative of a membrane. The polymersomes present as physical structures and SEM with a brush like exterior layer of PEG. One hour dialysis in water led to the same overall average diameter with solvent removal decreasing the polymersome diameter.When larger initial concentrations of organic solvent are used, larger diameter decreases are expected. While making the PEG-PLA polymersomes, modest changes in PDI are expected, which may indicate a change in shape. When dialyzing PEG-PLGA polymersomes, which are slightly more hydrophobic than PEG-PLA polymers against salt, the increase in PDI is more consistent with elongation with all explored salt gradients leading to an increase in PDI.Similar results should be observed when using a 50 millimolar salt gradient to cause a shape change regardless of polyester hydrophobicity. Meanwhile, 100 and 200 millimolar sodium chloride salt gradients display the direct trend that delta PDI increases with increasing polyester hydrophobicity. TEM images of PEG-PLA polymersomes dialyzed with 50 million lower sodium chloride showed with stomatocytes and elongated rods.As salt concentration increased to 100 millimolar, an increased number of rods formation with a decreased number of stomatocytes was observed. Dialysis against 200 millimolar polymersomes more consistently formed prolates with modest aspect ratios. The most challenging part of this protocol is making the polymersome consistently.So it is important to practice the procedure.

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