Probing the Intracellular Bio-Nano Interface in Different Cell Lines with Gold Nanostars

Abstract

Gold nanostars are a versatile plasmonic nanomaterial with many applications in bioanalysis. Their interactions with animal cells of three different cell lines are studied here at the molecular and ultrastructural level at an early stage of endolysosomal processing. Using the gold nanostars themselves as substrate for surface-enhanced Raman scattering, their protein corona and the molecules in the endolysosomal environment were characterized. Localization, morphology, and size of the nanostar aggregates in the endolysosomal compartment of the cells were probed by cryo soft-X-ray nanotomography. The processing of the nanostars by macrophages of cell line J774 differed greatly from that in the fibroblast cell line 3T3 and in the epithelial cell line HCT-116, and the structure and composition of the biomolecular corona was found to resemble that of spherical gold nanoparticles in the same cells. Data obtained with gold nanostars of varied morphology indicate that the biomolecular interactions at the surface in vivo are influenced by the spike length, with increased interaction with hydrophobic groups of proteins and lipids for longer spike lengths, and independent of the cell line. The results will support optimized nanostar synthesis and delivery for sensing, imaging, and theranostics.

Spiky Gold Nanoparticles for the Photothermal Eradication of Colon Cancer Cells

“…To better take into account the potential influence of bio-nano interactions and biomolecular corona on the BGNP cell uptake (which are protein concentration-dependent), in vitro experiments were performed using culture media supplemented with 50% of the serum to get closer to an in vivo-like scenario with regards to the protein concentration. A large excess of protein can influence the nature of the biomolecular corona and the interactions of BGNPs with the cell [ 65 ]. In fact, binding competition of the free proteins crowds the media and commonly leads to reduced uptake, especially for large NPs [ 66 ].…”

Surface enhanced Raman scattering for probing cellular biochemistry

“…13 The dependence of the endolysosomal spectra were very obvious in experiments with cells from different cell lines incubated with gold nanostars, due to the cell line specific processing of these nanoparticles. 39,40 In HCT-116 colorectal cancer cells, we found a higher abundance of amide III and lipids related bands, while 3T3 fibroblasts presented more signals from aromatic amino acid side chains, together with disulfide and carbon sulfide bands (Figure 3A and B). 40 Such differences in particle processing are already observed for short incubation times, as was studied for the nonmacrophage cell lines 3T3 and HCT-116, and J774 macrophages.…”

“…40 Such differences in particle processing are already observed for short incubation times, as was studied for the nonmacrophage cell lines 3T3 and HCT-116, and J774 macrophages. 39 One common trend in the SERS spectra of these cells incubated with nanostars is that depending on nanostar morphology, specifically the tip length, interaction with the surrounding intracellular biomolecules is quite different: for increasing tip length, SERS spectra show a higher abundance of lipid related bands and fewer protein related bands (Figure 3C). 39,40 Possible different active uptake processes in cells give rise to different SERS spectra not only from the different proteins and lipids of the vesicles, but also from differences in the culture medium and the protein corona that is formed.…”

“…The shape of the particles in known to have an effect on the cellular uptake and retention, 33,34 mediated by the protein corona composition and structure 35,36 together with conformational changes of proteins, 37,38 but less is known regarding the selectivity of nanoparticles of different shapes to probe physiological process other than particle uptake and transport. 39,40 When gold nanoparticles are generated directly inside cells, the biomolecular corona will vary strongly in comparison to endocyted particles. In situ formation of gold nanoparticles was shown in cell cultures of several animal cell lines and in their supernatant after incubation with tetrachloroauric acid in buffer, [41][42][43][44][45] and the SERS activity of the in situ generated nanoparticles was reported.…”

“…Reducing the complexity of the biological system to focus on particular biomolecules or functional groups and their different possibilities of interactions with the metallic nanostructures was shown to be extremely helpful to obtain a more detailed picture of intracellular processes. As will be discussed, this can help to understand, for example, the composition and structure of the protein corona of nanoparticles in living cells 73,74 and the impact of incubation time and cell line in the processing of nanostructures in the case of proteins, 39,40 the inhibition of lipid degradation and accumulation in vesicles, 13,96 and DNA degradation in cancer cells upon electrical stimulation induced apoptosis. 22…”