Characterisation of hydration and nanophase separation during the temperature response in hydrophobic/hydrophilic elastin-like polypeptide (ELP) diblock copolymers

Abstract

To understand the complex nanoscale dehydration process during the lower critical solution temperature (LCST) based inverse phase transition of a class of thermoresponsive biopolymers, diblock elastin-like polypeptides (ELPs) were investigated by spin probing continuous wave electron paramagnetic resonance (CW EPR) spectroscopy. The diblock copolymers composed of a hydrophobic block and a hydrophilic block showed different mechanisms of a temperature-driven phase transition. While the phase transition temperature is a function of the hydrophobic mass fraction of the diblock ELPs, the hydrophilic block length determines the molecular structure of the polymer aggregates formed above the transition temperature. When the weight ratio of hydrophilic block length to hydrophobic block length is greater than or equal to 0.3, the polymer aggregates consist of a hydrophobic core and a hydrophilic corona. The interface of these two regions become permeable at temperatures above the transition temperature. In case of smaller ratios, the aggregating hydrophobic parts of the polymer enclose the hydrated hydrophilic blocks, that are too small to form a hydrophilic corona, leading to bigger and less dense aggregates of higher polarity.

Serum albumin hydrogels in broad pH and temperature ranges: characterization of their self-assembled structures and nanoscopic and macroscopic properties

“…Albumin-FA interactions can then be monitored by observing immobilization of rotational motion upon FA binding to albumin 5,6 and according to changes in environmental polarity. [42][43][44] We use spin-labeled stearic acid derivatives, which we have shown to be bound by albumin (both HSA and BSA) in solution and which report on the availability and chemical nature of longchain fatty acid binding sites. 5,16 The stearic acids are spinlabeled at position 16 from the carboxylic acid headgroup, hence called 16-DSA (16-doxyl stearic acid, free radical, 253596, ALDRICH), bearing a nitroxide doxyl group, Fig.…”

A new thermoresponsive polymer of poly(N-acryloylsarcosine methyl ester) with a tunable LCST

“…The collected filtrate was concentrated by rotary evaporation under reduced pressure to afford the crude product. Further purification was achieved via flash chromatography on a silica gel eluting with ethyl acetate to give pale yellow liquid of NASME (14.13 13 C NMR spectra in Figure 1 and Figure S2. IR (KBr, cm Please do not adjust margins in 1,4-dioxane (2.60 g, 2.50 mL) were added.…”

“…The 1 H and 13 C nuclear magnetic resonance (NMR) analysis were performed on a Bruker Avance III 400 MHz NMR spectrometer equipped with a 5 mm standard probe. The internal solvent proton signals at δ = 7.26 ppm, δ = 4.70 ppm and δ = 2.50 ppm of the CDCl 3 , D 2 O and (CD 3 ) 2 SO were used as references, respectively.…”

“…[1][2][3] Amongst the thermoresponsive polymers, an abundance of macromolecules exhibiting a lower critical solution temperature (LCST) with a coil-to-globule transition in water solution, are probably the most investigated. To date, the LCSTtype thermoresponsive polymers can be summarized into six categories: poly[oligo(ethylene glycol) (meth)acrylate]s, [5][6][7] poly(2alkyl-2-oxazoline)s, 8,9 poly(vinyl methyl ether)s, 10,11 polypeptides, [12][13][14] N-alkyl-substituted poly(aminoethyl methacrylate)s, [15][16][17][18] and especially N-substituted poly(meth)acrylamides with a pendant of amide group. Recently, many kinds of technologies have verified that the amide pendant of polyacrylamide plays key role in forming hydrogen bonding with water or the additives (e.g.…”

Electrochemical characterization of the stimuli-response of surface-immobilized elastin-like polymers

“…[15][16][17][18] Currently, the broad scope of research applications using ELPs is, in part, facilitated by the robust preliminary characterization of physical properties and behaviour of ELPs in solution. [19][20][21][22][23] Surface-immobilized ELPs will operate differently than solution-based ELPs. In solution, ELPs are free to move within a 3D space, allowing for ELP aggregation to minimize interactions between the non-polar regions of ELPs and their environment.…”