ABSTRACT
A variety of research reports have provided evidence that the interplay between nanoparticles and biological systems is strongly dependent on the composition as well as on the size of the particles. However, irrespective of that a fine tuning of the interaction characteristics can be attained by functionalisation of the particle surface. In order to be able to monitor such interactions, an analytically accessible model system for potentially target-specific therapeutically relevant nanoparticles (NP) was generated by encapsulation of the highly hydrophobic fluorophore BODIPY 493/503 into poly(D,L-lactide-co-glycolide) (PLGA) nanodroplets. Analyses of the mean particle size and zeta potential revealed that plain and human serum albumin (HSA) conjugated NP can be stored without agglomeration for at least 28 days at 4 degrees C as well as -80 degrees C. Although transfer of the particles into commonly used buffers and cell culture medium did not affect the system's stability, protein-containing dispersants should not be used for experiments demanding high sensitivity as distinct quenching effects were observed. Concerning liberation of the fluorescent marker, no release occurred when incubating the suspension for 7 days at 4 degrees C, while an onset of release was expectedly detected after 3 h at 37 degrees C. These experimental limitations were taken into account for the particle-cell interaction studies which, as a consequence of the more hydrophilic particle surface, showed an enhanced adhesion of HSA-conjugated colloids to Caco-2 cells by means of flow cytometry and fluorescence microscopy.
Subject(s)
Boron Compounds/analysis , Cell Communication , Lactic Acid/chemistry , Nanoparticles/analysis , Polyglycolic Acid/chemistry , Boron Compounds/chemistry , Caco-2 Cells , Flow Cytometry , Humans , Microscopy, Fluorescence , Nanoparticles/chemistry , Particle Size , Polylactic Acid-Polyglycolic Acid Copolymer , Serum Albumin/chemical synthesis , Serum Albumin/chemistry , TemperatureABSTRACT
To overcome current limitations in diagnostic imaging and targeted drug delivery, a highly versatile tool is presented that can be used to representatively investigate the effects of submicroparticles intended for the use in biological systems. An effective approach to render colloids trackable is developed by stable attachment of the fluorescent probe BODIPY 493/503 (BOD: 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene) to a biodegradable and biocompatible particle core matrix. BOD submicroparticles are shown to be stable, can be surface modified, and exhibit high fluorescence emission. Upon conjugation with human serum albumin (nonspecific) and wheat germ agglutinin (biorecognitive) as model ligands explicit differences are found in the cytoadhesive and cytoinvasive characteristics of the submicroparticles using Caco-2 cells. These results demonstrate the potency of BOD-labeled colloids as a versatile analytical platform for a multifaceted investigation of cell-particle interactions in biological systems.
