Thermoresponsive Aggregation Behavior of Triterpene–Poly(ethylene oxide) Conjugates in Water

Abstract

Bioconjugate amphiphiles comprising triterpene and poly(ethylene oxide) (PEO) were studied according to their thermoresponsive aggregation behavior (LCST) in water. Cholesteryl-PEO (CE) and betulinyl-PEO (BE) comprising <70 wt% PEO precipitated from water upon heating. CE, but not BE, solutions contained nanoscopic aggregates at room temperature causing different thermoprecipitation behaviors. Solutions containing 5 wt% solutions of BE with short PEO chains demonstrated dual thermoresponsive behavior, precipitating at high temperature and forming hydrogel at low temperature. A BE multiblock copolymer was found to form large aggregates, presumably vesicles, in water. Results suggest that the solution properties of triterpene-PEO amphiphiles can be controlled by the chemical composition and structure.

Betulin-Constituted Multiblock Amphiphiles for Broad-Spectrum Protein Resistance

“…Previously, a bioconjugate polymer comprising a rigid, hydrophobic betulin entity in the center and soft, hydrophilic PEO chains on both sides (BEO) was synthesized by metal-free anionic ring-opening polymerization (ROP) . Interestingly, such an amphiphilic triblock-like structure, when dissolved in water, stays mostly as single molecules rather than form stable nanosized aggregates, despite substantially high hydrophobic content, which is most probably related to the viscoelastic effect (longer relaxation time than interaction time) derived from the peculiar molecular geometry and the rigidity of betulin units. , By reacting with an diacid chloride, BEO was turned into a segmented polyester and lost the solubility in water . It was anticipated that such a betulin-constituted multiblock-like structure might lack the ability to phase-separate and form hydrophobic nanodomains in its bulk.…”

“…27,28 By reacting with an diacid chloride, BEO was turned into a segmented polyester and lost the solubility in water. 29 It was anticipated that such a betulin-constituted multiblock-like structure might lack the ability to phase-separate and form hydrophobic nanodomains in its bulk. Together with the amphiphilicity and water-insolubility, this character would then lead to a competent protein-resistant coating material.…”

Synthesis and Self-Assembled Behavior of pH-Responsive Chiral Liquid Crystal Amphiphilic Copolymers Based on Diosgenyl-Functionalized Aliphatic Polycarbonate

“…[ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. In general, the morphologies and sizes of polymer micellar aggregates can be designed through molecular weight selection [ 8 , 9 , 10 ], chain architecture design [ 11 , 12 , 13 ], degree of crosslinking [ 6 , 14 ] and variation of solution conditions [ 1 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. So, a variety of smart nanomaterial systems are constructed by association of various kinds of amphipathic polymers, including proteins, DNA, and phospholipids, through well-controlled self-assembly [ 25 , 26 ].…”

Terpene and Dextran Renewable Resources for the Synthesis of Amphiphilic Biopolymers

“…[5][6][7] Among the examples of terpene-based polymers, [5][6][8][9][10][11][12] the synthesis of amphiphilic polymers were limited to the design of terpene end-modified poly(ethylene oxide) polymers by anionic ring-opening polymerization of ethylene oxide from terpene-based initiator. 13,14 In parallel, the increasing demand of materials with high performances requires modification of natural polymers. 15 Numerous examples of polysaccharide modification through synthetic polymer grafting via for instance controlled radical polymerization 16 or ring opening polymerization [17][18][19][20] techniques have been described in the literature.…”

“…H and13 C NMR spectra of initial DHM terpene, 1 H NMR of Terpene 2 and COSY 2D-NMR spectra of both synthesized functional terpenes are provided. This material is available free of charge via the Internet at http://pubs.acs.org.…”