Correction to: NPG Asia Materials (2015) 7, e160; doi:10.1038/am.2015.1; published online 20 February 2015

After publication of this article, it has come to our attention that there is a formatting error in this article. Header text in the article was not properly inserted. With publication of this erratum we have made correction to the article in both PDF and HTML versions. The error has now been rectified.

The publisher would like to apologize for any inconvenience caused.