We have established a method for synthesizing PMPC, a biocompatible polymer with phospholipid-like groups, on silica particles to produce hollow particles.The shell thickness of the hollow particles could be freely adjusted depending on the composition of the polymerization solvent. Using fluorescein as a model molecule, approximately 10% could be incorporated into the hollow core, achieving sustained release over 30–50 hours, which is expected to have medical applications such as drug carriers.
Silica nanoparticles with a radius of 150 nm functionalized with vinyl groups were used as templates. These were coated with poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) and a crosslinking agent using the graft-through method, followed by removal of the silica to obtain hollow PMPC.Evaluation by dynamic light scattering, infrared spectroscopy, thermal gravimetric analysis, and transmission electron microscopy revealed that the shell thickness could be adjusted by varying the composition of the polymerization solvent. When encapsulating fluorescein, approximately 80% was released in 30 hours and approximately 88% in 50 hours in a phosphate-buffered solution, demonstrating its potential as a biocompatible sustained-release carrier. Applications in medical nanocapsules and enzyme isolation media are also anticipated.
Biocompatible poly(2-methacryloyloxyethyl phosphocholine) (PMPC) has a phosphocholine group in its side chain, which is the same as the hydrophilic part of phospholipids that form biological membranes. This property makes PMPC attractive as a medical material for protein adsorption and inhibition of blood coagulation.On the other hand, hollow polymer particles are lightweight and capable of incorporating water-soluble drugs into their internal spaces, making them promising for applications such as drug delivery systems (DDS), catalyst supports, and photonic materials. However, conventional methods for creating hollow particles through self-assembly struggle to precisely control pore size and shell thickness, prompting the use of template-based hollow particle fabrication methods.The results of this study are positioned as foundational technology for the precise design of functional nano-hollow particles with biocompatibility.
PMPC, which possesses a phosphocholine group identical to the hydrophilic portion of phospholipids in its side chain, exhibits high biocompatibility, including protein adsorption and inhibition of blood coagulation, making it a promising candidate for medical material coatings and drug delivery systems (DDS). On the other hand, hollow particles, which can encapsulate hydrophilic drugs in their internal space and exhibit lightweight properties and high dispersion stability, are expected to be applied to various fields such as DDS, catalysts, and photonics. However, self-assembly methods make it difficult to precisely control pore size and shell thickness, so methods using templates are more convenient.In this study, silica particles with a radius of 150 nm were used as templates, and PMPC was polymerized around the silica using the graft-through method. The silica was then removed to obtain hollow PMPC. By varying the solvent used during polymerization, the shell thickness can also be adjusted.
Hollow PMPC particles were able to control the encapsulation and controlled release of guest molecules in water. By adjusting the composition of the solvent during polymerization, the shell thickness can be regulated, enabling control over release rate and mechanical strength.Applications are anticipated for anticancer agents, enzyme delivery, cell isolation beads, and contrast agents. Furthermore, by incorporating thermosensitive shells into the shell, it is possible to develop advanced systems such as stimulus-responsive drug delivery systems (DDS). By utilizing templates other than silica, it is also possible to create polyhedral, rod-shaped, and multilayer hollow particles, making this a highly versatile next-generation soft material platform with significant potential for further development.
| Research | |
|---|---|
| Journal | Langmuir |
| Title | Preparation of Biocompatible Poly(2-(methacryloyloxy)ethyl phosphorylcholine) Hollow Particles Using Silica Particles as a Template |
| Author | Sayaka Fujii, Shohei Kozuka, Kaito Yokota, Kazuhiko Ishihara, Shin-ichi Yusa |
| Member | Sayaka Fujii, Shohei Kozuka, Kaito Yokota, Shin-ichi Yusa |
| URL | https://pubs.acs.org/doi/10.1021/acs.langmuir.2c00423 |
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