Intracellularly Biodegradable Polyelectrolyte/Silica Composite Microcapsules as Carriers for Small Molecules

Area of Science:

• Materials Science
• Biomedical Engineering
• Nanotechnology

Background:

• Traditional biodegradable polyelectrolyte (PE) capsules struggle to encapsulate small molecules.
• Efficient drug delivery requires microcapsules that can be loaded with therapeutics and degraded at the target site.

Purpose of the Study:

• To develop a novel composite microcapsule capable of encapsulating small molecules and degrading within cells for targeted drug delivery.
• To investigate the degradability and drug release characteristics of poly-l-arginine hydrochloride (PARG)/dextran sulfate sodium salt (DEXS)/silica (SiO2) composite capsules.

Main Methods:

• Fabrication of PARG/DEXS/SiO2 composite microcapsules using layer-by-layer (LbL) assembly and tetraethoxysilane (TEOS) hydrolysis.
• Preparation of non-degradable poly(allylamine hydrochloride) (PAH)/poly(sodium 4-styrenesulfonate) (PSS)/SiO2 capsules as a control.
• Intracellular degradation studies using B50 cells and monitoring of Rhodamine B (Rh-B) release.

Main Results:

• PARG/DEXS/SiO2 capsules degraded within 2 hours in cells, releasing encapsulated Rhodamine B (Rh-B).
• PAH/PSS/SiO2 control capsules remained intact for over 3 days, indicating polymer component's role in SiO2 degradability.
• The degradation mechanism for PARG/DEXS/SiO2 capsules involves both silica hydrolysis and polymer enzymatic degradation.

Conclusions:

• A new type of biodegradable composite microcapsule (PARG/DEXS/SiO2) was successfully developed.
• These microcapsules demonstrate efficient loading of small molecules and rapid intracellular degradation, suitable for medical applications.
• The findings highlight the potential of these functional microcapsules for drug delivery systems due to their biocompatibility and biodegradability.