Synthesis and characterization of thermo-responsive particles of poly(hydroxybutirate-co-hydroxyvalerate)-b-poly(N-isopropylacrylamide)

Abstract

A new kind of thermo-responsive particles were prepared by the self-assembly technique, comprising poly(hydroxyvalerate-co-hydroxybutirate)-b-poly(N-isopropylacrylamide)/ (PHBHV-b-PNIPAAm) block copolymers. The hydrophilic part PNIPAAm was synthesized by Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization. Particles with core-shell morphology were obtained with hydrophilic outer shells and hydrophobic inner cores. Dexametasone acetate (DexAc) was used as a model drug with an encapsulation efficiency of 77%. The release of DexAc in aqueous solution was strongly dependent on temperature, suggesting that PHBHV-b-PNIPAAm particles can be used as a thermo-responsive carrier material with external control in a drug release system.

Polimerização RAFT em Miniemulsão

“…Porém, somente em 2007 [25] é que foram publicadas de fato as primeiras pesquisas experimentais envolvendo pesquisadores brasileiros com o tema. Outros artigos sobre polimerização RAFT, envolvendo a participação de pesquisadores brasileiros, vêm sendo publicados até a presente data [23,[26][27][28][29][30][31][32][33] , sendo algumas dessas totalmente desenvolvidas em universidades brasileiras [29,[31][32][33] . O tema da polimerização RAFT também já foi abordado recentemente, de forma resumida, em outras publicações nacionais [27] .…”

Application of 2K Experimental Design and Response Surface Methodology in the Optimization of the Molar Mass Reduction of Poly (3-Hydroxybutyrate-co-3-Hydroxyvalerate) (PHBHV)

“…Poly(3-hydroxybutirate) (PHB) and its copolymers with hydroxyvalerate (HV) are the most studied PHAs in literature [8]. PHB and PHBHV are completely biodegradable and produced by a variety of bacteria´s fermentation, [1] degrading throughout natural biological processes, turning them into excellent candidates for bioactive molecules release system´s production [9][10][11][12][13][14][15]. Both poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) are biodegradable thermoplastic polyesters produced by a bacteria known as Ralstonia eutropha or Alcaligenes latus [16].…”

“…One promising approach to improve their physical properties, adjusting degradation rates, dues to synthesizing block copolymers using telechelic PHB or PHBHV of low molar mass through chemical routes. These modifications involve reactions with bromide or chloride molecules turning these polymers macro-initiators, which can trigger a new polymerization with various monomers in order to obtain new materials type graft [30][31] or block [12,29,[47][48] copolymers with specific properties, for example, amphiphilic systems for drug carrier. Figure 3 shows some possible modifications that can be done to improve PHBHV with low molar mass proprieties.…”

“…and co-authors synthesized PHBHV-b-PNIPAAm block copolymers reacting hydroxyl-caped PHBHV of low molar mass and carboxyl-caped PNIPAAm obtained via reversible addition-fragmentation chain transfer (RAFT) polymerization. The thermo-responsive particles were loaded with dexametasone acetate (DexAc) and showed drug delivery behaviour dependent of temperature, suggesting that these polymeric micelles can be utilized as drug delivery systems [12]. Baran, ET.…”

Stimulus-responsive polymeric nanoparticles for biomedical applications

“…Zhuo et al have conducted systematic research concerning drug delivery systems based on amphiphilic PNIPAAm-based polymers [45][46][47][48][49][50], including investigating the effect of polymer structures on drug entrapment efficiency, enhancing the stability of the micelles through core/shell cross-linking, modulating the transition temperature of nanoparticles through incorporation of the hydrophilic/hy- Figure 2 The mechanism of the controlled drug release of drug loaded thermal-responsive nanoparticles [44]. drophobic monomers, and incorporating the targeting groups and functional groups to the polymer chains.…”