Nanoparticles LPSiNPs and TiO2

Researchers from California and Massachusetts have come up with a new type of non-toxic nanoparticle (NP) that is efficiently broken down and excreted by the kidneys once it has delivered its drug cargo to the target organ [Park, et al., Nat. Mater. (2009), doi: 10.1038/nmat2398].

There is already a significant amount of research on drug delivery using NPs, but some of these systems suffer from major drawbacks, such as the body’s immediate rejection of NPs before they can deliver their payload, or biodegradability and toxicity of the NPs or their by-products. However, the use of NPs for drug delivery remains of major interest because these small bodies have some exceptional properties. NPs have a large specific capacity for loading drugs, they are easily detected while they are in the body, and they are retained by the blood stream long enough for them to reach their target and offload the drug.

The new 126 nm luminescent porous Si NPs (LPSiNPs) are fabricated by electrochemical etching of single-crystal Si wafers, followed by ultrasonication and filtration to obtain NPs with 5-10 nm pore diameters. Silicon oxide grown onto the surface of LPSiNPs gives them an intrinsic photoluminescence at 650-900 nm. This makes them suitable for in vivo applications as organs and tissues exhibit very low adsorption in this region and any photoluminescence can be attributed to the LPSiNPs. The luminescent material is much more photostable than fluorescein or cyanin fluorophores and has a quantum yield comparable to other water-soluble luminescent silicon-silica NPs.

In vivo tests have been carried out by the researchers who incorporated an anti-cancer drug – doxorubicin – into LPSiNPs (DOX-LPSiNPs) and injected the DOX-LPSiNPs into mice. Photoluminescence indicates that the DOX-LPSiNPs reach the tumor, where they build up. Histology of the tissues also confirms the presence of the drug together with LPSiNPs inside the tumor. The LPSiNPs then break down, most probably into soluble silicic acid and are completely eliminated from the body by renal clearance within 1-4 weeks of injection, without any signs of toxicity in the major organs of the mice.

http://www.materialstoday.com/archive/2009/12-04/news01.html



TiO2 particles in various concentrations were added into culture plated with confluent cells. After incubation for 24 hours the cell viability was then quantified with Live/Dead cytotoxicity Viability stain (Molecular Probes). The cell viabilities were then normalized with cells without treatment. Vertical lines denote ± 1 SD (n = 4 for all test samples and cells). Significance of differences between cancer cells versus 3T3 cells: P < .05.



LLC cancer cells derived from mouse tumour tissues
JHU prostate cancer cells
B16F1 and B16F10 skin melanoma cancer cells
3T3 fibroblast cells (as control)



........we find that TiO2 nanoparticles have low cytotoxicity to B16F10 and B16F1 melanoma cells as well as 3T3 fibroblasts. These findings are in agreement with many recent published results. Specifically, various sizes and concentrations of TiO2 particles have been reported to be nontoxic in cell monolayer uptake models in vitro,[40] and [41] in vitro inhalation models,3 and in vivo models.[5] and [10] However, in the case of the JHU prostate tumor cells and LLC cells, we found that there are significant differences in viability levels for uncoated TiO2 particles at concentrations of 1 mg/mL for LLC cells and 0.1 mg/mL for JHU prostate tumor cells. Our results have shown that TiO2 particles possess cell-specific toxicity, depending on the concentrations and surface functionality of the particular particles.


Thevenot P et al, Univ of Texas, Surface chemistry influences cancer killing effect of TiO2 nanoparticles, Nanomedicine: Nanotechnology, Biology and Medicine, Volume 4, Issue 3, September 2008, Pages 226-236