Cellular Uptake and Fate of PEGylated Gold Nanoparticles Is Dependent on Both Cell-Penetration Peptides and Particle Size

Abstract

Numerous studies have examined how the cellular delivery of gold nanoparticles (AuNPs) is influenced by different physical and chemical characteristics; however, the complex relationship between AuNP size, uptake efficiency and intracellular localization remains only partially understood. Here we examine the cellular uptake of a series of AuNPs ranging in diameter from 2.4 to 89 nm that are synthesized and made soluble with poly(ethylene glycol)-functionalized dithiolane ligands terminating in either carboxyl or methoxy groups and covalently conjugated to cell penetrating peptides. Following synthesis, extensive physical characterization of the AuNPs was performed with UV-vis absorption, gel electrophoresis, zeta potential, dynamic light scattering, and high resolution transmission electron microscopy. Uptake efficiency and intracellular localization of the AuNP-peptide conjugates in a model COS-1 cell line were probed with a combination of silver staining, fluorescent counterstaining, and dual mode fluorescence coupled to nonfluorescent scattering. Our findings show that AuNP cellular uptake is directly dependent on the surface display of the cell-penetrating peptide and that the ultimate intracellular destination is further determined by AuNP diameter. The smallest 2.4 nm AuNPs were found to localize in the nucleus, while intermediate 5.5 and 8.2 nm particles were partially delivered into the cytoplasm, showing a primarily perinuclear fate along with a portion of the nanoparticles appearing to remain at the membrane. The 16 nm and larger AuNPs did not enter the cells and were located at the cellular periphery. A preliminary assessment of cytotoxicity demonstrated minimal effects on cellular viability following peptide-mediated uptake.

Ultrasmall Conjugated Polymer Nanoparticles with High Specificity for Targeted Cancer Cell Imaging

“…With the rapid advances of nanotechnology, versatile NP systems including semiconducting quantum dots (QDs), gold NPs, and dye encapsulated NPs, etc., have been developed 12, 13, 14, 15, 16. Despite the fact that NPs with varied sizes have been designed for different biomedical applications,17, 18, 19 there has been limited success in highly selective cancer targeting, and only a few examples for inorganic gold NPs were reported 16, 20. This is attributed to the precise size control of inorganic NPs to be smaller than 10 nm, as NPs with sizes ranging from 20 to 200 nm are able to be nonspecific internalized into cells which significantly compromises the detection selectivity 21, 22, 23, 24, 25.…”

Particle size- and number-dependent delivery to cells by layered double hydroxide nanoparticles

“…Of these characteristics, the particle size is a crucial factor which determines NP endocytosis pathway [17,18], uptake rate and efficiency [6,16,[19][20][21][22], in vitro cytotoxicity [23][24][25][26][27][28], immune responses [27][28][29][30], and the final localisation [15,31,32]. Thus size-dependent uptake of various NPs has been intensively investigated and widely reported.…”

Photothermal ablation of inflammatory breast cancer tumor emboli using plasmonic gold nanostars

“…20 This compartmentalization can be attributed to the relatively large size of GNS (50 nm), which precludes their entry into the nuclear membrane pores. 54,55 In addition, ICP-OES analysis revealed consistent nanoparticle uptake and cellular retention across cell lines over a 24-hour period. When transitioned to a 3D tumor emboli model, nanoparticle endocytosis was confined to the periphery of the larger SUM190 tumor emboli compared to its SUM149 and rSUM149 counterparts.…”