Hydrolytic Degradation of Pluronic F127/Poly(lactic acid) Block Copolymer Nanoparticles

Abstract

Poly(lactic acid)s (PLA) were grafted to both ends of Pluronic F127 (PEO-PPO-PEO) to produce novel amphiphilic PLA-F127-PLA block copolymers. The hydrolytic degradation of PLA-F-127-PLA block copolymers in phosphate buffered saline (PBS) (pH 7.4) solution at 37°C was studied using a combination of physical techniques, such as dynamic light scattering (DLS), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). It was found that the morphologies and particle size of PLAF127-23 nanoparticles changed dramatically because of the initial rapid degradation of PLA blocks. The morphology of the microstructure transformed from the regular onionlike vesicles to large compound vesicles. With increasing time, the degradation rate of LA-LA linkage was reduced, and the degradation mainly occurred at the interface of F127 and PLA blocks. The morphologies of PLAF127-23 nanoparticles changed from the regular larger compound vesicles to irregular compound vesicles, and to regular large compound vesicles as degradation progresses. Accordingly the particle size of PLAF127-23 nanoparticles decreased initially and remained constant for a certain time period, and it then increased again.

Characterizing Biodegradation of PLA and PLA‐g‐AA/Starch Films Using a Phosphate‐Solubilizing Bacillus Species

“…The formation of fragments also implies that starch had been nearly depleted by this time. Agarwal et al [18] and Xiong and Tam [19] reported similar results. The retention time of fragments was approximately invariant and this may be due to the utilization by the bacterium of depolymerized matrix as substrate, which produces nearly uniform fragments.…”

Polymeric micelles: authoritative aspects for drug delivery

“…They proposed the micelles to possess high thermodynamic stability and suitable as long circulating carriers in the context of antineoplastic and antibiotic drug delivery [276]. The hydrolytic degradation of poly(lactic acid)-Pluronic F127-poly(lactic acid) nanoparticles has been reported by Xiong et al [277,278]. They noted that the hydrolytic degradation of the amphiphilic block copolymers affected the sizes and morphologies of these nanoparticles.…”

Amphiphilic multiblock copolymers of PLLA, PEO and PPO blocks: Synthesis, properties and cell affinity

“…Polymerization proceeded in an argon environment at 180°C for 15 h. In aqueous solutions, PLLA/Pluronic Ò F-127 copolymers (M n = 23, 29 and 48 kg mol À1 ) are able to arrange themselves in onion-like vesicles with two or three layers, presenting diameters of approximately 80-100 nm [19]. The release of hydrophobic and hydrophilic model drugs by these vesicles [20], and also their hydrolytic [21] and enzymatic [22] degradation in vitro, were evaluated in several studies. PLLA/Pluronic Ò F-87 copolymers (M n = 9.0, 9.4 and 10.4 kg mol À1 ) can self-assemble in several structures, such as micelles with diameters of approximately 20 nm or network-like aggregates with diameters of approximately 300-700 nm.…”