ABSTRACT
In recent years colloidal particles and capsules, layer-by-layer (LbL) coated with biocompatible polyelectrolytes, have received much attention as drug-delivery systems. In this study an LbL-assembled, biopolymer-based multilayer system was established as a combined transporter and sensor for monitoring intracellular degradation and processing. CaCO(3) cores were functionalized with fluorescein isothiocyanatelabelled poly(allylamine hydrochloride) (FITC-PAH). This pH-sensitive fluorescent dye allows identifying the location of these LbL-coated particles in cell compartments of different pH, like the endo-lysosome and cytoplasm. The labelled core was then coated with consecutive layers of protamine (PRM) and dextran sulfate (DXS). Finally, plasmid DNA (pEGFP-C1) as a reporter agent for drug release in the cytoplasm was integrated into the biocompatible and degradable PRM/DXS multilayer. The system was tested regarding its long-term stability and interaction with HEK 293T/17 cells. These multifunctional microparticles allow the simultaneous investigation of particle localization and processing within cells, and should thus provide a valuable tool for studying and improving the controlled LbL-based release of active agents into cells.
Subject(s)
Cell Compartmentation , Drug Carriers/chemistry , Plasmids/administration & dosage , Biological Transport , Calcium Carbonate , Coated Materials, Biocompatible , Colloids/chemistry , Dextran Sulfate/chemistry , Flow Cytometry , Fluorescein-5-isothiocyanate , Fluorescent Dyes , HEK293 Cells , Humans , Hydrogen-Ion Concentration , Microscopy, Confocal , Protamines/chemistryABSTRACT
Multifunctional colloidal microparticles allow the integration of various active agents as well as reporter molecules into one system without interfering combining delivery and sensing functions. In this study, calcium carbonate particles were functionalized with fluorescein isothiocyanate-labeled poly(allylamine hydrochloride) (FITC-PAH) allowing particle localization in cell compartments of different pH. Plasmid DNA (pEGFP-C1 and pDsRed1-N1) as a reporter agent for drug release in the cytoplasm and rhodamine-B-isothiocyanate-labeled protamine (RITC-PRM) were integrated into biocompatible and biodegradable PRM/DXS multilayers. The uptake and processing of the particles by HEK293T/17 cells were investigated via flow cytometry and confocal laser scanning microscopy. The presented data show a clear correlation between the fluorescence intensity of the FITC-labeled core, that is, the particle localization after cellular uptake, and the expression of fluorescent proteins by the cells without further cell staining. In conclusion, this particle design allows the simultaneous study of particle location and processing to monitor the transport and release of active agents and should thus be an invaluable tool for the study and design of nano- and microcarrier systems.
