DLS and zeta potential - What they are and what they are not?

The antibacterial action of silver is utilized in numerous consumer products and medical devices. Metallic silver, silver salts, and also silver nanoparticles are used for this purpose. The state of research on the effect of silver on bacteria, cells, and higher organisms is summarized. It can be concluded that the therapeutic window for silver is narrower than often assumed. However, the risks for humans and the environment are probably limited.

Silver as Antibacterial Agent: Ion, Nanoparticle, and Metal

Nanoparticles have been proposed as carriers for drugs, genes and therapies to treat various diseases. Many strategies have been developed to target nanomaterials to specific or over-expressed receptors in diseased cells, and these typically involve functionalizing the surface of nanoparticles with proteins, antibodies or other biomolecules. Here, we show that the targeting ability of such functionalized nanoparticles may disappear when they are placed in a biological environment. Using transferrin-conjugated nanoparticles, we found that proteins in the media can shield transferrin from binding to both its targeted receptors on cells and soluble transferrin receptors. Although nanoparticles continue to enter cells, the targeting specificity of transferrin is lost. Our results suggest that when nanoparticles are placed in a complex biological environment, interaction with other proteins in the medium and the formation of a protein corona can 'screen' the targeting molecules on the surface of nanoparticles and cause loss of specificity in targeting.

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Transferrin-functionalized nanoparticles lose their targeting capabilities when a biomolecule corona adsorbs on the surface

Cell-derived nanoparticles have been garnering increased attention due to their ability to mimic many of the natural properties displayed by their source cells This top-down engineering approach c

http://pubs.acs.org/doi/pdf/10.1021/nl500618u

Cancer Cell Membrane-Coated Nanoparticles for Anticancer Vaccination and Drug Delivery

Nanoparticles enter cells through active processes, thanks to their capability of interacting with the cellular machinery. The protein layer (corona) that forms on their surface once nanoparticles are in contact with biological fluids, such as the cell serum, mediates the interactions with cells in situ. As a consequence of this, here we show that the same nanomaterial can lead to very different biological outcomes, when exposed to cells in the presence or absence of a preformed corona. In particular, silica nanoparticles exposed to cells in the absence of serum have a stronger adhesion to the cell membrane and higher internalization efficiency, in comparison to what is observed in medium containing serum, when a preformed corona is present on their surface. The different exposure conditions not only affect the uptake levels but also result in differences in the intracellular nanoparticle location and impact on cells. Interestingly, we also show that after only one hour of exposure, a corona of very different nature forms on the nanoparticles exposed to cells in the absence of serum. Evidence suggests that these different outcomes can all be connected to the different adhesion and surface properties in the two conditions.

/pdf/effects-of-the-presence-or-absence-of-a-protein-corona-on-25ugdpxbzn.pdf

Effects of the presence or absence of a protein corona on silica nanoparticle uptake and impact on cells

Nanoparticles are considered a primary vehicle for targeted therapies because they can pass biological barriers and enter and distribute within cells by energy-dependent pathways. So far, most studies have shown that nanoparticle properties, such as size and surface, can influence how cells internalize nanoparticles. Here, we show that uptake of nanoparticles by cells is also influenced by their cell cycle phase. Although cells in different phases of the cell cycle were found to internalize nanoparticles at similar rates, after 24 h the concentration of nanoparticles in the cells could be ranked according to the different phases: G2/M > S > G0/G1. Nanoparticles that are internalized by cells are not exported from cells but are split between daughter cells when the parent cell divides. Our results suggest that future studies on nanoparticle uptake should consider the cell cycle, because, in a cell population, the dose of internalized nanoparticles in each cell varies as the cell advances through the cell cycle.

Role of cell cycle on the cellular uptake and dilution of nanoparticles in a cell population

The interaction of nanoscaled materials with biological systems is currently the focus of a fast-growing area of investigation. Though many nanoparticles interact with cells without acute toxic responses, amino-modified polystyrene nanoparticles are known to induce cell death. We have found that by lowering their dose, cell death remains low for several days while, interestingly, cell cycle progression is arrested. In this scenario, nanoparticle uptake, which we have recently shown to be affected by cell cycle progression, develops differently over time due to the absence of cell division. This suggests that the same nanoparticles can trigger different pathways depending on exposure conditions and the dose accumulated.

/pdf/low-dose-of-amino-modified-nanoparticles-induces-cell-cycle-1cx0di748o.pdf

Low dose of amino-modified nanoparticles induces cell cycle arrest

Nanomaterials challenge paradigms of in vitro testing because unlike molecular species, biomolecules in the dispersion medium modulate their interactions with cells. Exposing cells to nanoparticles known to cause cell death, we observed cytotoxicity suppression by increasing the amount of serum in the dispersion medium towards in vivo-relevant conditions.

Suppression of nanoparticle cytotoxicity approaching in vivo serum concentrations: limitations of in vitro testing for nanosafety

Nano-sized objects interact with biological systems in fundamentally novel ways, thereby holding great promise for targeted drug delivery. It has also been suggested they could constitute a hitherto unseen hazard. Numerous experimental studies in the field are taking place. We consider that the nature of the interactions allows a more fundamental theoretical framework to be developed. In particular, we describe the intimate link that develops between nanoparticle uptake and cell population evolution. Explicit analytical results are given and the theory compared to experimental observations.

/pdf/theoretical-framework-for-nanoparticle-uptake-and-w7wh3k080z.pdf

Theoretical framework for nanoparticle uptake and accumulation kinetics in dividing cell populations

/pdf/reply-to-the-interface-of-nanoparticles-with-proliferating-pmx2zattqz.pdf

Jong Ah Kim

Papers

Role of cell cycle on the cellular uptake and dilution of nanoparticles in a cell population

Low dose of amino-modified nanoparticles induces cell cycle arrest

Suppression of nanoparticle cytotoxicity approaching in vivo serum concentrations: limitations of in vitro testing for nanosafety

Theoretical framework for nanoparticle uptake and accumulation kinetics in dividing cell populations

Reply to 'The interface of nanoparticles with proliferating mammalian cells'.