1. Could you explain the significance of your article to the non-specialist? 

Non-spherical-colloidal-particles and their arrays have attracted great attention because of their unique properties that their spherical counterparts do not possess. However, it still remains a challenge on direct synthesis of these non-spherical particles as well as formation of their ordered arrays. In this paper, an extremely simple and effective method to fabricate arrays of colloidal spheres with nanoholes was developed. Both the size and the depth of the nanoholes can be controlled. The techniques involved in this method, such as fabrication of large-scale colloidal monolayer, electrochemical deposition of uniform metal layer, and dry etching are mature, thus the method described here allows the production of arrays of colloidal spheres with nanoholes in a high-throughput and cost-effective manner.

2. What has motivated you to conduct this work? 

So far, several methods have been developed to prepare colloidal spheres with nanoholes. The group led by Professor Yang S.-M. in Korea has described the reactive ion etching of colloidal spheres with infiltrated materials or upper layer as etching mask. However, the control of the nanoholes size seems difficult. Other nanohole methods like E-beam lithography and focused ion beam (FIB) are time-consuming and expensive. For practical applications of these colloidal nanomaterials, availability of a simple and cost-effective method is urgent, which motivates us to conduct this work.

3. Where do you see this work developing in the future? 

We expect numerous applications for these colloidal nanostructures, among which are photonics, sensing, microanalysis, separations, cell-growth and beyond. In addition, these colloidal spheres with nanoholes can be further decorated by means of surface modification or incorporation of functional materials within the nanoholes to meet the requirement of some other applications.

4. Are there any particular challenges facing future research in this area? 

The fabrication of high-quality colloidal nanostructures will continue to be a focus of intense research in the future in this area. For practical applications, however, there are some challenges remaining. One lies in colloidal self assembly itself. The fabrication of defect-free colloidal monolayer in large-domains is not mature yet. Others like how to introduce functional elements into such nanomachined colloidal spheres for biosensor and drug delivery applications must also be addressed. Nevertheless, I do see a brilliant future of the nanostructures described in this work in many emerging applications.