Table 2.
Summary of available reports on the exocytosis of NPs
| NPs | NPs’ Feature | Cell line* | Highlighted factor | Methods for exocytosis detection | Remark | Ref |
|---|---|---|---|---|---|---|
| Silica | 50 nm | H1299, NE083, NL20 | Effect of cell line | Confocal microscopy and TEM | The type of cell line is a dominant factor in the excretion profile of NPs. In the case of H1299 cells, the clusters of silica NPs in lysosomes are more easily exocytosed than single NPs in cytoplasm. | 192 |
| Silica | N/A | HUVECs, HeLa | Effect of cell line | Flow cytometry and confocal microscopy | Different retention and excretion abilities of normal and cancerous cell lines could lead to asymmetric cell-to-cell transfer of MSNs | 250 |
| Silica | 130 nm | A549, MDA-MB231, MCF-7, MDA-MB435, PANC-1, H9 | Effect of different abilities of lysosomal excretion/Effect of surface modification/Effect of extracellular calcium concentration | Flow cytometry and inductively coupled plasma-optical Emission spectroscopy (ICP-OES) | Lysosomal exocytosis plays a key role in the exocytosis process. Different surface modifications at the surface of NPs (phosphonate, folate, and PEI) change the exocytosis profile of NPs. The treatment of A549 cells with Ionomycin (an ionophore that transports calcium into cells) enhanced the exocytosis rate of the phosphonated NPs | 251 |
| Silica | 60, 180, 370, and 600 nm | HepG2 | Effect of NPs’ size | Flow cytometry | Smaller NPs are more easily cleared from HepG2 cells. Cellular exocytosis of these NPs was largely dependent on time. | 252 |
| Gold | 14, 30, 50, 74 and 100 nm (Rods/Spheres) | HeLa, SNB19, STO | Effect of cell line and Effect of size and shape of NPs | Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and TEM | The proportion of rod-shaped NPs excreted from HeLa and SNB19 cells was much higher than spherical-shaped NPs. No observable difference in the amount of excreted rod-shaped and spherical-shaped NPs from STO cells. The exocytosis rate of 14 nm transferrin-coated Au NPs was two/five times faster than that of 74 nm and 100 nm NPs, respectively. (This trend was observed in three different cell lines) | 253 |
| Gold | Nanorods (length of 55 and width of 13 nm) | A549, 16HBE, MSC | Effect of cell line | Flow cytometry and inductively coupled plasma mass spectrometry (ICP-MS) | The cytotoxicity and exocytosis profile of NPs in cancer cells was different from that of normal and stem cells. | 254 |
| Gold | 35 nm and charge 18 mV | HUVECs | Effect of NPs surface modification | ICP-AES | Functionalization with non-targeting or targeting peptides yield different exocytosis profiles | 255 |
| Gold | 10 nm | HT-29 | Effect of extracellular calcium concentration | Absorbance plate reader | The concentration of excreted NPs from HT-29 cells was proportional to calcium concentration | 256 |
| Diamond | 100 nm | HeLa, 3T3-L1, and stromal cell lines | Effect of cell line | Flow cytometry | Exocytosis of the same NPs on various cells was significantly different. This observation could be important in the development of new NPSplatforms for cell-tracking and drug-delivery applications | 257 |
| SPIONs | 15 and 30 nm (trapped in porous silicon carriers) | J774 | Effect of NPs Size | SPECTRA max M2 plate reader | Smaller NPs were exocytose more easily from J774 cells compared to the larger NPs | 258 |
| Carbon nanotube | Rod (with length of 660, 430, 320 and 130 nm) | NIH-3T3 | Effect of nanotube length | Single-particle tracking (SPT) | Smaller NPs were exocytosed more easily than larger ones | 203 |
| PLGA NPs | 97 | VSMCs | Comparison between excretion rate of Lucifer yellow (molecular weight of ~450 Da) and PLGA (143,000 Da) | Confocal microscopy and HPLC | Smaller NPs or molecules were trapped in the rapid-recycling compartment, while the majority of larger molecules entered the slow-recycling compartment. Excretion of smaller NPs is thus much easier. The pre-incubation time of NPs before exocytosis did not show any considerable effect. Sodium azide and deoxyglucose reduced the exocytosis of PLGA NPs by 40% compared to the control group | 204 |
| Poly(methyl methacrylate)-block-poly(polyethylene glycol methyl ether methacrylate NPs | 20 and 25 nm | OVCAR-3 | Effect of crosslinking | Fluorescence spectroscopy | Crosslinked micelles were removed from cells more easily than non-crosslinked NPs | 259 |
| N-acetyl histidine-conjugated glycol chitosan NPs | 150–250 nm | HeLa | Effect of pre-incubation time | Confocal microscopy | The amount of excreted NPs was dependent on the pre-incubation time prior to removal of free NPs from the culture media | 260 |
| QDs | 22 to 25 nm (Cd/Se QDs) | HeLa and A549 Xenograft Tumor Models | Different binding stability between targeting moiety (transferrin) and the receptor | Fluorescence-activated cell sorting (FACS) and Fluorescence imaging | Binding between transferrin-QDs and receptor extended the intracellular NPS retention intervals | 261 |
| QDs | 65 nm (Si-QDs) | HUVECs | Effect of exposure time and NPs concentration | Confocal laser scanning microscopy (CLSM) | The exocytosis profile of Si-QDs depended on exposure time and exposed NPs concentration in cell culture | 262 |
| Silver | 6–20 nm | U251 | Effect of incubation time and NPs concentration | ICP-OES | Direct correlation between incubation time and NPS concentration with NPs excretion from cells | 263 |
| CuO | 20–40 nm | A549 | Effect of exposure time, NPs concentration, and intracellular distribution | Atomic absorption spectrometry (AAS) | The proportion of CuO NPs that were expelled from A549 was enhanced by increasing the exposure time and NPS concentration. A portion of NPs located in mitochondria and nucleus could not be excreted. | 205 |
| Maltodextrin | 60 nm | HBE | Effect of cholesterol depletion | Confocal microscopy | The exocytosis of these NPs stopped after application of filipin (an agent that extracts membranous cholesterol). | 264 |
*
Human lung carcinoma (H1299), human esophageal epithelial (NE083) and human bronchial epithelial (NL20) cells, human umbilical vein endothelial cells (HUVECs) and human fibroblast epithelial cells (HeLa), adenocarcinomic human alveolar basal epithelial cells (A549), breast cancer cell lines (MDA-MB231 and MCF-7), the melanoma cancer cell line (MDA-MB435), the pancreatic cancer cell line (PANC-1), and the human embryonic stem cell line (H9), hepatocellular cell line (HepG2), human glioblastoma (SNB 19) and mouse embryonic fibroblast (STO), human bronchial epithelial cells (16-HBE), mesenchymal stem cells(MSC), human colonic adenocarcinoma cell lines (HT-29), pre-adipocytes cells (3T3-L1), murine macrophages cell line (J774), mouse embryonic fibroblast cell line (NIH-3T3), human vascular smooth muscle cells (VSMCs), human ovarian cancer cell lines (OVCAR-3), human glioblastoma cells (U251)