title: Humid Heat Autoclaving of Hybrid Nanoparticles Achieved by Decreased Nanoparticle Concentration and Improved Nanoparticle Stability Using Medium Chain Triglycerides as a Modifier.
abstract: Humid heat autoclaving is a facile technique widely used in the sterilization of injections, but the high temperature employed would destroy nanoparticles composed of biodegradable polymers. The aim of this study was to investigate whether incorporation of medium chain triglycerides (MCT) could stabilize nanoparticles composed of poly (ethylene glycol)-b-polycaprolactone (PEG-b-PCL) during autoclaving (121°C, 10 min).
  
  
  
  Polymeric nanoparticles with different MCT contents were prepared by dialysis. Block copolymer degradation was studied by GPC. The critical aggregation concentrations of nanoparticles at different temperatures were determined using pyrene fluorescence. The size, morphology and weight averaged molecular weight of pristine/autoclaved nanoparticles were studied using DLS, TEM and SLS, respectively. Drug loading content and release profile were determined using RP-HPLC.
  
  
  
  The protecting effect of MCT on nanoparticles was dependent on the amount of MCT incorporated. Nanoparticles with high MCT contents, which assumed an emulsion-like morphology, showed reduced block copolymer degradation and particle disassociation after incubation at 100°C for 24 h. Nanoparticles with high MCT content showed the lowest critical aggregation concentration (CAC) under either room temperature or 60°C and the lowest particle concentration among all samples. And the particle size, drug loading content, physical stability and release profile of nanoparticles with high MCT contents remained nearly unchanged after autoclaving.
  
  
  
  Incorporation of high amount of MCT changed the morphology of PEG-b-PCL based nanoparticles to an emulsion-like structure and the nanoparticles prepared could withstand autoclaving due to improved particle stability and decreased particle concentration caused by MCT incorporation.
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China.
authors.forename: Jingxin
authors.initials: J
authors.lastname: Gou
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Chao
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China.
authors.forename: Yuheng
authors.initials: Y
authors.lastname: Liang
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China.
authors.forename: Haibing
authors.initials: H
authors.lastname: He
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Yin
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China. xuhui-spu@163.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, 110016, China. tanglab@126.com.
authors.forename: Xing
authors.initials: X
authors.lastname: Tang
mesh_terms: D004355:Drug Stability; D006358:Hot Temperature; D007783:Lactones / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D013242:Sterilization / Q000379:methods; D014280:Triglycerides / Q000737:chemistry*
chemical_list: D007783:Lactones; D011108:Polymers; D014280:Triglycerides; C521904:poly(ethylene glycol)-block-poly(epsilon-caprolactone); D011092:Polyethylene Glycols
keywords: autoclaving; block copolymer; medium chain triglycerides; oil-containing nanoparticles; polymer degradation; stability