Han Y et al. (2016), Synthesis of Novel Temperature- and pH-Sensitiv...

ECB-ART-47130

Polymers (Basel) 2016 Nov 11;811:. doi: 10.3390/polym8110367.

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Synthesis of Novel Temperature- and pH-Sensitive ABA Triblock Copolymers P(DEAEMA-co-MEO₂MA-co-OEGMA)-b-PEG-b-P(DEAEMA-co-MEO₂MA-co-OEGMA): Micellization, Sol⁻Gel Transitions, and Sustained BSA Release.

Han Y , Liu S , Mao H , Tian L , Ning W .

Abstract
Novel temperature- and pH-responsive ABA-type triblock copolymers, P(DEAEMA-co-MEO₂MA-co-OEGMA)-b-PEG-b-P(DEAEMA-co-MEO₂MA-co-OEGMA), composed of a poly(ethylene glycol) (PEG) middle block and temperature- and pH-sensitive outer blocks, were synthesized by atom transfer radical polymerization (ATRP). The composition and structure of the copolymer were characterized by ¹H NMR and gel permeation chromatography (GPC). The temperature- and pH-sensitivity, micellization, and the sol⁻gel transitions of the triblock copolymers in aqueous solutions were studied using transmittance measurements, surface tension, viscosity, fluorescence probe technique, dynamic light scattering (DLS), zeta-potential measurements, and transmission electron microscopy (TEM). The lower critical solution temperature (LCST) of the triblock copolymer, which contains a small amount of a weak base group, (N,N-diethylamino) ethyl methacrylate (DEAEMA), can be tuned precisely and reversibly by changing the solution pH. When the copolymer concentration was sufficiently high, increasing temperature resulted in the free-flowing solution transformation into a micellar gel. The sol-to-gel transition temperature (Tsol⁻gel) in aqueous solution will continue to decrease as solution concentration increases.

PubMed ID: 30974672
PMC ID: PMC6431942
Article link: Polymers (Basel)
Grant support: [+]

Genes referenced: eif3d

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References [+] :

Determan, Supramolecular self-assembly of multiblock copolymers in aqueous solution. 2007, Pubmed

	Scheme 1. Schematic illustration of the synthesis of ABA triblock copolymer P(DEAEMA-co-MEO2MA-co-OEGMA)-b-PEG-b-P(DEAEMA-co-MEO2MA-co-OEGMA).
	Figure 1. Transmittance curves of: (a) P1, P2, P3, P4 in aqueous solutions versus pH at 25 °C; (b) P2 in aqueous solution versus temperature at different pH; (c) P1, P2, P3, P4 in aqueous solutions versus temperature; and (d) P5, P2, P6, P7 in aqueous solutions versus temperature. (0.5 mg·mL−1).
	Figure 2. Surface tension curve of P2 aqueous solution (0.5 mg·mL−1, pH 7) versus temperature.
	Figure 3. Viscosity curves of 1 wt % P2 in aqueous solution versus temperature at different pH values.
	Figure 4. Curves of the I3/I1 ratio of pyrene (Py) at 25 °C for various concentrations of P2 aqueous solution at pH 5, 7, and 10.
	Figure 5. The aggregate particle diameters in P2 aqueous solution as a function of temperature (a) and solution pH (b) at 25 °C (0.5 mg·mL−1).
	Figure 6. Zeta potentials of P2 aqueous solution (1.5 mg·mL−1) versus pH at 25 °C.
	Figure 7. TEM images of micelles of P2 at 46 °C in acid medium (a) and basic medium (b).
	Scheme 2. Micellization and gelation process of the ABA triblock copolymer.
	Figure 8. The temperature induced sol–gel phase diagrams of P2 aqueous solution (a) and 30 mg·mL−1 P2 aqueous solution at different pH (b).
	Figure 9. Photo of P2 aqueous solution at 25, 32, 37, 43, 65, and 75 °C (30 mg·mL−1, at pH 1.2, 7.4, and 11.8).
	Figure 10. The cumulative release curves of bovine serum albumin (BSA) at different temperatures (a) and different pH (b).