title: Steric environment around acetylcholine head groups of bolaamphiphilic nanovesicles influences the release rate of encapsulated compounds.
abstract: Two bolaamphiphilic compounds with identical acetylcholine (ACh) head groups, but with different lengths of an alkyl chain pendant adjacent to the head group, as well as differences between their hydrophobic skeleton, were investigated for their ability to self-assemble into vesicles that release their encapsulated content upon hydrolysis of their head groups by acetylcholinesterase (AChE). One of these bolaamphiphiles, synthesized from vernolic acid, has an alkyl chain pendant of five methylene groups, while the other, synthesized from oleic acid, has an alkyl chain pendant of eight methylene groups. Both bolaamphiphiles formed stable spherical vesicles with a diameter of about 130 nm. The ACh head groups of both bolaamphiphiles were hydrolyzed by AChE, but the hydrolysis rate was significantly faster for the bolaamphiphile with the shorter aliphatic chain pendant. Likewise, upon exposure to AChE, vesicles made from the bolaamphiphile with the shorter alkyl chain pendant released their encapsulated content faster than vesicles made from the bolaamphiphile with the longer alkyl chain pendant. Our results suggest that the steric environment around the ACh head group of bolaamphiphiles is a major factor affecting the hydrolysis rate of the head groups by AChE. Attaching an alkyl chain to the bolaamphiphile near the ACh head group allows self-assembled vesicles to form with a controlled release rate of the encapsulated materials, whereas shorter alkyl chains enable a faster head group hydrolysis, and consequently faster release, than longer alkyl chains. This principle may be implemented in the design of bolaamphiphiles for the formation of vesicles for drug delivery with desired controlled release rates.
authors: Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: Avital
authors: A
authors: Stern
authors: Istituto di Scienze e Tecnologie Molecolari-CNR, Milano, Italy.
authors: Matteo
authors: M
authors: Guidotti
authors: Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: Eleonora
authors: E
authors: Shaubi
authors: Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: Mary
authors: M
authors: Popov
authors: Zuckerberg Water Institute and Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: Charles
authors: C
authors: Linder
authors: Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: Eliahu
authors: E
authors: Heldman
authors: Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: Sarina
authors: S
authors: Grinberg
mesh_terms: D000109:Acetylcholine / Q000737:chemistry; D000110:Acetylcholinesterase; D016503:Drug Delivery Systems; D005452:Fluoresceins / Q000008:administration & dosage; D005456:Fluorescent Dyes / Q000008:administration & dosage; D005663:Furans / Q000737:chemistry*; D006801:Humans; D006868:Hydrolysis; D015394:Molecular Structure; D053769:Nanocapsules / Q000737:chemistry* / Q000648:ultrastructure; D050997:Nanomedicine; D011728:Pyridones / Q000737:chemistry*
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D005663:Furans; D053769:Nanocapsules; D011728:Pyridones; C543575:bolaamphiphile; C024098:6-carboxyfluorescein; D000110:Acetylcholinesterase; D000109:Acetylcholine
keywords: acetylcholine; acetylcholinesterase; bolaamphiphiles; controlled release; drug delivery; vesicles