Macromolecular crowding improves polymer encapsulation within giant lipid vesicles

Lisa M. Dominak, Christine D. Keating

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

We report the effect of macromolecular crowding on encapsulation efficiency of fluorescently labeled poly(ethylene glycol)(PEG) and dextran polymers within individual giant lipid vesicles (GVs). Low concentrations of the fluorescently labeled polymers (82 nM to 186 μM) were mixed with varying concentrations of nonfluorescent polymers that served as crowding agents during vesicle formation by gentle hydration. Encapsulation efficiency of the fluorescently labeled polymers in individual GVs (EE ind) was determined via confocal fluorescence microscopy. EE ind for high molecular weight polymers (e.g., fluorescein isothiocyanate (FITC)-dextran 500 and 2000 kDa) increased substantially in the presence of several weight percent unlabeled PEG or dextran. For example, when 0.24 μM FITC dextran 500 kDa was encapsulated, addition of 3% PEG 8 kDa improved the mean concentration in the GVs from 0.14 μM (±50%) to 0.24 μM((12%). Light scattering data indicate reduced hydrodynamic radii for polymers as a function of increasing polymer concentration, suggesting that the improvements in EE ind result from polymer condensation due to macromolecular crowding. Polymeric cosolutes did not significantly impact EE ind for lower molecular weight polymers (e.g., Alexa Fluor 488-PEG 20 kDa), which already encapsulated efficiently (EE ind ̃ 1). However, for both the higher and lower molecular weight labeled polymers, cosolutes led to improved uniformity in EE ind for vesicles within a batch. Methods for improving the value and homogeneity of EE ind for polymeric solutes in lipid vesicles are important in a variety of applications, including the use of vesicles as microreactors and as vehicles for drug delivery.

Original languageEnglish (US)
Pages (from-to)13565-13571
Number of pages7
JournalLangmuir
Volume24
Issue number23
DOIs
StatePublished - Dec 2 2008

Fingerprint

crowding
Encapsulation
Lipids
lipids
Polymers
polymers
dextrans
Dextran
Polyethylene glycols
Molecular weight
low molecular weights
Dextrans
Confocal microscopy
Fluorescence microscopy
Drug delivery
Hydration
Light scattering
homogeneity
hydration
glycols

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

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abstract = "We report the effect of macromolecular crowding on encapsulation efficiency of fluorescently labeled poly(ethylene glycol)(PEG) and dextran polymers within individual giant lipid vesicles (GVs). Low concentrations of the fluorescently labeled polymers (82 nM to 186 μM) were mixed with varying concentrations of nonfluorescent polymers that served as crowding agents during vesicle formation by gentle hydration. Encapsulation efficiency of the fluorescently labeled polymers in individual GVs (EE ind) was determined via confocal fluorescence microscopy. EE ind for high molecular weight polymers (e.g., fluorescein isothiocyanate (FITC)-dextran 500 and 2000 kDa) increased substantially in the presence of several weight percent unlabeled PEG or dextran. For example, when 0.24 μM FITC dextran 500 kDa was encapsulated, addition of 3{\%} PEG 8 kDa improved the mean concentration in the GVs from 0.14 μM (±50{\%}) to 0.24 μM((12{\%}). Light scattering data indicate reduced hydrodynamic radii for polymers as a function of increasing polymer concentration, suggesting that the improvements in EE ind result from polymer condensation due to macromolecular crowding. Polymeric cosolutes did not significantly impact EE ind for lower molecular weight polymers (e.g., Alexa Fluor 488-PEG 20 kDa), which already encapsulated efficiently (EE ind ̃ 1). However, for both the higher and lower molecular weight labeled polymers, cosolutes led to improved uniformity in EE ind for vesicles within a batch. Methods for improving the value and homogeneity of EE ind for polymeric solutes in lipid vesicles are important in a variety of applications, including the use of vesicles as microreactors and as vehicles for drug delivery.",
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Macromolecular crowding improves polymer encapsulation within giant lipid vesicles. / Dominak, Lisa M.; Keating, Christine D.

In: Langmuir, Vol. 24, No. 23, 02.12.2008, p. 13565-13571.

Research output: Contribution to journalArticle

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