Exocytosis of peptide functionalized gold nanoparticles in endothelial cells

Abstract

We present the exocytosis profile of two types of peptide-coated nanoparticles, which have similar charge and size but different functionality. While one kind of particles appears to progressively exocytose, the other one has a more complex profile, suggesting that some of the particles are re-uptaken by the cells. Both types of particles retain their colloidal stability after exocytosis.Understanding the interactions of functional nanoparticles with biological cells is of tremendous importance not only for new developments in sensing, imaging and therapy but also for realizing the fundamental cellular mechanisms and cytotoxicity of nanomaterials.1-5 With an accumulated knowledge of how the size, shape and functionality of nanomaterials influence their fate in cells, one should be able to synthesize nanoparticles on demand, with appropriate functionality and which are best suited to a particular application. This means that particles would be designed to (a) be taken up by the cell in desirable numbers, (b) deliberately escape from the endosomes, (c) access the cytoplasm and migrate selectively through the cell for a given time, (d) target specific compartments and organelles (i.e. nucleus, mitochondria) to perform desired tasks and (e) exocytose in high numbers leaving the cell intact. Following these aims, several research groups have successfully investigated various aspects of interactions between functional nanoparticulate systems and cells.6-14 For example, Brust and co-workers shed light on the intracellular fate of spherical gold nanoparticles coated with cell penetrating peptides and suggested ways of pre-programming nanoparticle migration within the cytoplasm.15,16 Alternatively Mirkin and colleagues performed a systematic study on the internalization rate of DNA modified gold nanoparticles and suggested new directions for targeted gene therapy.17,18 Our group and others have investigated how the size, shape and charge of nanoparticles influence their cellular uptake, [19][20][21][22][23] and how the number of endocytosed particles correlates with the nanoparticles' heating efficiency during laser hyperthermia. 20,24Despite the extensive work on gold nanoparticle uptake and intracellular fate, 7,25 a very limited number of papers have discussed the exocytosis of functional gold nanoparticles. 26 Since gold is one of the most promising candidates for biomedical applications in the near future, exocytosis studies are of great importance, because they are directly correlated with chronic cytotoxicity and nanoparticle intracellular retention times.In this paper we investigated the cellular uptake and exocytosis of two types of peptide functionalized gold nanospheres by an important category of mammalian cells, namely human endothelial cells (HUVECs). The specific types of particles were chosen due to their ease of preparation and particular function. To keep our studies consistent, both types of nanoparticles were designed to have similar hydrodynamic size and charge. The first batch of nanoparticles ('inh...

Mammalian cells preferentially internalize hydrogel nanodiscs over nanorods and use shape-specific uptake mechanisms

“…This allows effective comparison of uptake kinetics between different cells and avoids saturation. Decrease in median fluorescence observed at 48 h in HUVECs could be a result of faster particle dilution per cell because of cell division and low particle dose or due to endothelial cell-specific exocytosis (31). Although these PEGDA particles are not degradable in water in the time frame studied, oxidative degradation inside some cells could also be a possible cause of the observed fluorescence decrease.…”

Endocytosis and exocytosis of nanoparticles in mammalian cells

“…The exocytosis of peptide-coated gold nanoparticles was also investigated in endothelial cells. 41 Nanoparticles functionalized with KATWLPPR peptides have been known to bind to plasma membrane receptors on endothelial cells for endocytosis, while nanoparticles coated with KPRQPSLP peptides did not interact with the receptors for endocytosis. KATWLPPR peptide-coated nanoparticles taken up by cells were progressively exocytosed up until 6 hours.…”

Gold Nanoparticle Surface Functionalization: A Necessary Requirement in the Development of Novel Nanotherapeutics

“…Typically GNPs entering the cell are endocytosed via clathrin coated vesicles, which fuse with endosomes then progress towards lysosomal degradation and exocytosis. Endosomal disruption motifs have been conjugated to the surface of GNPs to disrupt the endocytotic pathway, a process which differs depending on the functionalization of the GNP [60] but generally results in exocytosis [61]. Endosomal escape mechanisms have become increasingly popular in order to increase intracellular distribution and therapeutic surface area and allow organelle targeting.…”