Thermosensitivity of Bile Acid‐Based Oligo(ethylene glycol) Stars in Aqueous Solutions

Abstract

Amphiphilic star-shaped oligo(ethylene glycol)s with a hydrophobic bile acid core and varying number of hydrophilic arms have been made. Their thermal behavior in aqueous solutions depends on the number rather than the length of the arms. The two-armed lithocholate derivative showed the strongest tendency for association and exhibited the lowest cloud point (79 °C) of the oligomers made, as well as another phase separation at a lower temperature (31 °C). The "double thermosensitivity" arising both from the salt-dependent LCST of the oligo(ethylene glycol) segments and the temperature-responsive self-assembly of amphiphilic bile acid derivative provides an interesting path in the design of bile acid-based smart materials.

Synthesis of Terpene-Based Polymers

“…Anionic ROP of epoxides have been performed using the OHs on bile acid molecules as initiating sites, with potassium naphthalene as the deprotonation agent [148][149][150]. Prior to the polymerization, the COOH is turned into OH by reduction or amidation.…”

“…5 C) to high (ca. 82 C) temperature [149]. Star polymers with cholic acid core and poly(allyl glycidyl ether) arms were prepared and subjected to thiol-ene chemistry to introduce COOH or NH 2 groups in the arms (Scheme 20).…”

pH-Responsive Micelles Assembled by Three-Armed Degradable Block Copolymers with a Cholic Acid Core for Drug Controlled-Release

“…Cholic acid (CA), a naturally occurring bile acid, is derived from liver cells in the human body. Due to its special structure, cholic acid and its derivatives have attracted the attention of researchers, and their application in drug controlled-release systems has been reported extensively [27,28,29,30]. Zhu and co-workers reported the synthesis of series polymers based on CA, and using them in drug delivery systems.…”

Synthesis of terpene–poly(ethylene oxide)s by t-BuP4-promoted anionic ring-opening polymerization

“…[26][27][28][29] Biohybrids of terpenes and PEO have been prepared and studied as water-soluble prodrugs 30,31 or as functional polymeric amphiphiles. [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] The synthetic diblock copolymer of PEO and polyisoprene has long been a well-studied subject in polymer science with respect to its physical properties (e.g. amphiphilicity) as well as chemical activities.…”

“…32,33 Most of the hybrid amphiphiles based on natural terpene molecules reported to date bear cholesteryl entities. [35][36][37][38][39][40][41][42][43][44][45][46][47] Cholesteryl-end-capped linear PEO has been studied quite a lot in terms of self-assembly behavior 35,36 and biomedical functions such as optimizing gene and drug delivery systems by increasing transfection efficiency and the stability in blood circulation. [37][38][39] Recently, cholesterol-PEO-based branched polymers have also been prepared either by coupling cholesterol onto the functionalized PEO chain ends [40][41][42] or by polymerizing ethylene oxide (EO) anionically from cholesteryl entities.…”