Protein delivery nanosystem of six-arm copolymer poly(ε-caprolactone)–poly(ethylene glycol) for long-term sustained release

Abstract

BackgroundTo address the issue of delivery of proteins, a six-arm copolymer, six-arm poly (ε-caprolactone)–poly(ethylene glycol) (6S-PCL-PEG), was synthesized by a simple two-step reaction. Thereafter, the application of 6S-PCL-PEG as a protein carrier was evaluated.Materials and methodsA six-arm copolymer, six-arm poly(ε-caprolactone) (6S-PCL), was synthesized by ring-opening polymerization, with stannous octoate as a catalyst and inositol as an initiator. Then, poly(ethylene glycol) (PEG) was linked with 6S-PCL by oxalyl chloride to obtain 6S-PCL-PEG. Hydrogen-1 nuclear magnetic resonance spectrum, Fourier-transform infrared spectroscopy, and gel-permeation chromatography were conducted to identify the structure of 6S-PCL-PEG. The biocompatibility of the 6S-PCL-PEG was evaluated by a cell counting kit-8 assay. Polymeric nanoparticles (NPs) were prepared by a water-in-oil-in-water double emulsion (W1/O/W2) solvent evaporation method. The size distribution and zeta potential of NPs were determined by dynamic light scattering. Transmission electron microscopy was used to observe the morphology of NPs. Drug-loading capacity, encapsulation efficiency, and the release behavior of ovalbumin (OVA)-loading NPs were tested by the bicinchoninic acid assay kit. The stability and activity of OVA released from NPs were detected and the uptake of NPs was evaluated by NIH-3T3 cells.ResultsAll results indicated the successful synthesis of amphiphilic copolymer 6S-PCL-PEG, which possessed excellent biocompatibility and could formulate NPs easily. High drug-loading capacity and encapsulation efficiency of protein NPs were observed. In vitro, OVA was released slowly and the bioactivity of OVA was maintained for over 28 days.Conclusion6S-PCL-PEG NPs prepared in this study show promising potential for use as a protein carrier.

Highly sensitive H2O2-scavenging nano-bionic system for precise treatment of atherosclerosis

“…Dry CH 2 Cl 2 (10 mL) was measured and stirred with steamed oxalyl chloride (10 mmol) in an ice bath. PEG-Ar-OH (2 mmol) and TEA (2 mmol) were dissolved in dried CH 2 Cl 2 , poured into a dropping funnel with constant pressure, the dripping process was slow and under the protection of nitrogen, and then the mixture was stirred continuously in an ice bath for 3 h under the protection nitrogen 33 . When the reaction was completed, impurities were removed by rotary evaporation, and a solid substance was left after the drying process.…”

Sustained Release Systems for Delivery of Therapeutic Peptide/Protein

“…79 In another work of Yang et al, a six-arm amphiphilic PCL−PEG (6S− PCL−PEG) copolymer was synthesized and loaded with ovalbumin (OVA), forming 6S−PCL−PEG nanoparticles (∼190 nm) via a W/O/W double emulsion method with high drug loading capacity of ∼28.5% benefiting from its starshaped structure. 71 The in vitro release curve indicated that the release of OVA was up to 28 days profiting from the conformational cloud formed by 6S−PCL−PEG copolymer in aqueous solution. Apart from formulating into particles for controllable delivery of protein therapeutics, PCL was also applied in the surface coating of other sustained-release formulations for further controllable release of target therapeutics due to its moderate film-forming property.…”

“…with protein molecular weights ranging from 5,000 to 60,000 were approved by the FDA. − But the circulation time of the PEGylated protein still does not meet the needs for long-term treatment of chronic diseases such as diabetes and cerebral degenerative diseases. So synthetic polymers such as PLGA, poly­(ε-caprolactone- co -glycolic acid) (PCGA), poly­( l -lactide- co -caprolactone) (PELCL), and polyamines, PLA, among others, are designed and synthesized to form copolymers with PEG for construction of protein/peptide long-acting formulations. − For instance, in the work of Boury et al, based on the phase separation method, PLGA–PEG self-assembled into nanoparticles (∼255 nm) and successfully loaded stromal cell-derived factor-1α (SDF-1α) precipitates with loading capacity for ∼0.03%. The in vitro release profile suggested that the initial burst release of SDF-1α was high, up to ∼40% on day 1, and the total release period of this chemokine was extended to approximately 3 days .…”

“…These PCL–PEG microparticles effectively extended the in vitro release of VEGF to approximately 4 weeks with only 20% drug release on day 7 and successfully extended the release period of VEGF up to 28 days thanks to the low degradability rate of PCL . In another work of Yang et al, a six-arm amphiphilic PCL–PEG (6S–PCL–PEG) copolymer was synthesized and loaded with ovalbumin (OVA), forming 6S–PCL–PEG nanoparticles (∼190 nm) via a W/O/W double emulsion method with high drug loading capacity of ∼28.5% benefiting from its star-shaped structure . The in vitro release curve indicated that the release of OVA was up to 28 days profiting from the conformational cloud formed by 6S–PCL–PEG copolymer in aqueous solution.…”