Preparation of Polypseudorotaxanes Composed of Cyclodextrin and Polymers in Microspheres

Abstract

We prepared polypseudorotaxanes (PPRXs) composed of cyclodextrin (CyD) and polyethylene glycol (PEG) inside microspheres (MSs) by an emulsifying process using polypropylene glycol (PPG) that shows temperature-dependent hydrophilicity changes; PPG is hydrophobic at high temperatures but hydrophilic at low temperatures. An aqueous solution of CyD and PEG was dispersed as droplets in PPG at 60°C then cooled to 0°C to allow water of droplets to transfer into PPG. On removal of water in the droplets, CyD and PEG were left behind as a CyD/PEG PPRX inside the solid-state MSs. Examination of α-, β-, and γ-CyD revealed that α-CyD was suitable for the formation of PPRX containing PEG in this MS preparation procedure. Interestingly, a new PPRX composed of α-CyD and PPG was formed in the α-CyD MSs when they were prepared in the absence of PEG from the aqueous solution of α-CyD. This MS fabrication procedure can control the size and shape of PPRX particles, and will contribute to the production of new types of CyD inclusion complexes. Key words cyclodextrin (CyD); microsphere (MS); polyethylene glycol (PEG); polypropylene glycol (PPG); polypseudorotaxane (PPRX)Cyclodextrins (CyDs) are cyclic oligosaccharides composed of 6, 7, or 8 glucopyranoside units, which are named α-, β-, and γ-CyD, respectively. CyDs consist of a hydrophobic cavity in which hydrophobic molecules are enclosed to form an inclusion complex. CyDs are widely used as a pharmaceutical additive for their ability to improve the solubility and stability of drugs via CyD complexation.

Biocompatible Polymers Combined with Cyclodextrins: Fascinating Materials for Drug Delivery Applications

“…Polyrotaxanes (PRXs) and polypseudorotaxanes (PPRXs) are different examples of host-guest interlocked complexes in which linear molecule or polymer are encircled by macrocyclic components (e.g., CDs) [128]. The influence of the formation of PPRXs during the microparticles (MPs) preparation was investigated for the system composed of CDs and PEG [129]. The emulsifying process, using polypropylene glycol (PPG) as an oil phase and CDs with and without PEG as a water Polyrotaxanes (PRXs) and polypseudorotaxanes (PPRXs) are different examples of host-guest interlocked complexes in which linear molecule or polymer are encircled by macrocyclic components (e.g., CDs) [128].…”

Self-Healable, Fast Responsive Poly(ω-Pentadecalactone) Thermogelling System for Effective Liver Cancer Therapy

“…The micelles formed from PDEP copolymers are typically composed of a hydrophobic core and hydrophilic corona (Nakashima and Bahadur, 2006). The presence of PPG segments, well-known for exhibiting hydrophilicity at lower temperature and hydrophobicity at higher temperature, endows the copolymer micelles with thermal sensitivity (Shinohara et al, 2014). To investigate this property, the hydrodynamic diameter distribution by intensity for 2PDEP micelles in aqueous solutions (1 mg·mL −1 ) were investigated by DLS at two different temperatures (25 and 70°C).…”