Metal based and CNT based are frequently reported to cause toxicity.

U can go through the following links, these are few publications with updated info. U can find enough literature in scholar search.

http://pubs.rsc.org/en/content/articlelanding/2015/cs/c4cs00177j/unauth#!divAbstract

http://www.sciencedirect.com/science/article/pii/S0001868615000433

http://www.sciencedirect.com/science/article/pii/S002628621400168X

http://www.tandfonline.com/doi/abs/10.1080/15533174.2013.831448#.VSFFC_mUdHM

yes  they impart toxicity as a drug delivery system.

the polymers used for delivery induces toxicity and their patern of drug release.

Thank you Arpan.

Can you suggest some article / s.

I hope it is good introducton:

http://en.wikipedia.org/wiki/Nanotoxicology

Metal based and CNT based are frequently reported to cause toxicity.

U can go through the following links, these are few publications with updated info. U can find enough literature in scholar search.

http://pubs.rsc.org/en/content/articlelanding/2015/cs/c4cs00177j/unauth#!divAbstract

http://www.sciencedirect.com/science/article/pii/S0001868615000433

http://www.sciencedirect.com/science/article/pii/S002628621400168X

http://www.tandfonline.com/doi/abs/10.1080/15533174.2013.831448#.VSFFC_mUdHM

Some more for your taste - Good luck

• Toxicological perspectives of inhaled therapeutics and nanoparticles, 2014

http://informahealthcare.com/doi/abs/10.1517/17425255.2014.916276

• Toxicological Assessment of Inhaled Nanoparticles: Role of in Vivo, ex Vivo, in Vitro, and in Silico Studies, 2014 

http://www.mdpi.com/1422-0067/15/3/4795

• Toxicology of engineered nanomaterials - a review of carcinogenic potential. 2009

http://www.apocpcontrol.org/page/apjcp_issues_view.php?sid=Entrez:PubMed&id=pmid:20192569&key=2009.10.6.975

Thanks Andrei, Rajesh and Murugesan

The toxicity of nanomaterials is a quite complex issue because it depends on the type of particle, on size, surface properties, the exposure route, and of course the dose. There are different types of toxicity - cytotoxicity, genotoxicity, immunotoxicity, etc. General statements are, therefore, not possible. Also CNTs are not always toxic - it depends on their dimensions; short ones for instance have very low cytotoxicity.

Thanks: Eleonore Froehlich