Negotiation of Intracellular Membrane Barriers by TAT-Modified Gold Nanoparticles

Abstract

This paper contributes to the debate on how nanosized objects negotiate membrane barriers inside biological cells. The uptake of peptide-modified gold nanoparticles by HeLa cells has been quantified using atomic emission spectroscopy. The TAT peptide from the HIV virus was singled out as a particularly effective promoter of cellular uptake. The evolution of the intracellular distribution of TAT-modified gold nanoparticles with time has been studied in detail by TEM and systematic image analysis. An unusual trend of particles disappearing from the cytosol and the nucleus and accumulating massively in vesicular bodies was observed. Subsequent release of the particles, both by membrane rupture and by direct transfer across the membrane boundary, was frequently found. Ultimately, near total clearing of particles from the cells occurred. This work provides support for the hypothesis that cell-penetrating peptides can enable small objects to negotiate membrane barriers also in the absence of dedicated transport mechanisms.

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

“…Lysosomotropic agents such as chloroquine and sucrose have been shown to disrupt endosomal membranes, increasing availability of DNA delivery agents [62], and intracellular GNPs [63]. Nanoparticle functionalization's have attempted to replicate this with some success, TAT-functionalised GNPs were found freely in the cytosol, managing to successfully negotiate intracellular barriers, due to the rapid escape of particles from the endocytic system or by direct translocation of the particles across the plasma membrane, or indeed both [64].…”

Applications of nanomaterials as vaccine adjuvants

“…40,80 For nonviral delivery systems, pH-responsive nanoparticles, cationic nanoparticles, and nanoparticles functionalized with CPPs have been explored for this cytosolic delivery purpose. 38,39 Nanoparticles modified with pH-responsive peptides or linkers undergo structural deformation or degradation under acidic pH, which disrupts their transfer across the endosomal membrane. 81,82 For example, OVA encapsulated within pH-sensitive liposomes was shown to be 3-6 times stronger in inducing CTL responses compared with pH-insensitive liposomes.…”

“…38,80 Tat-modified gold nanoparticles (»14 nm) can negotiate intracellular membrane barriers; these particles are initially found in the cytosol but later enter the nucleus, mitochondria and vesicles. 39 In another study, octaarginine (R8, also a CPP) was attached to liposomes to investigate the cytosolic delivery of OVA for MHC class I presentation. Comparing OVA-encapsulated R8 liposomes to pH-sensitive and cationic liposomes, R8 liposomes showed superior ability to increase MHC class I presentation, OVA-specific CTL responses and antitumor responses over other formulations.…”

“…From the limited literature on nanoparticle clearance, removal of non-degradable nanomaterials from live cells seems to occur mainly through exocytosis. 39,147 Diffusional movement of nanoparticles through cell membranes is unlikely to occur under normal conditions. Transferrin (Tf)-coated spherical-shaped Au nanoparticles (Tf-Au) are exocytosed from cells in a linear relationship with their size, 147 whereas smaller Tf-Au particles appear to exocytose at a faster rate and higher percentage than larger Tf-Au particles.…”

“…[29][30][31][32][33][34][35][36][37] To further facilitate antigen entry into a cell, cell-penetrating peptides (CPPs) and viral-like nanosurfaces have been applied. 23,24,[38][39][40] More recently, smart nanoparticles have been manufactured using pH-sensitive or redox-sensitive materials; 23,24,[40][41][42][43] these environment-responsive nanoparticles enable controlled release of antigens at target sites and more adequate release of antigens from endo-lysosomal compartments, thus enhancing antigen presentation. In addition to their delivery function, a great number of nanoparticles have shown immunomodulatory effects, particularly for innate immune signaling.…”