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New nanoparticles target deep-lying cancer

10 October 2012

Prof Zhang with PhD student and co-author Mr Gnananasammandhan in the lab

Near infrared light, which is non-toxic, is able to penetrate deeper into tissues
NUS researchers have developed a new technology that holds promise for a safe and non-invasive method of treating cancer.

Headed by Associate Professor Zhang Yong from the Department of Bioengineering, the six-member team - from NUS Faculties of Engineering and Science as well as Yong Loo Lin School of Medicine - has demonstrated that their discovery could stop cancer cells from growing and control gene expression in mice.

The discovery, published online recently in Nature Medicine and the journal Proceedings of the National Academy of Sciences, USA, is the first in the world using nanoparticles for photodynamic therapy of deep-seated cancer.

The group used nanoparticles which are able to change near-infrared (NIR) light to visible or ultraviolet (UV) light. When introduced into target sites of the patient, they can be manipulated to control gene expression.

Genes release certain proteins in our body to regulate the body's internal workings and health. When the process goes wrong, the body malfunctions, leading to various diseases. UV light can be exploited to control the process of gene expression but the procedure carries safety risks.

The scientists have applied the nanoparticles to other light-based therapies to produce visible light. Conventional light therapy for treating tumours takes visible light to activate light-sensitive drugs which destroy cancer cells but such visible light is not strong enough to penetrate to tumours in deep-lying sites.

Assoc Prof Zhang said: "NIR, besides being non-toxic, is also able to penetrate deeper into our tissues. When NIR reaches the desired places in the body of the patient, the nanoparticles which we have invented are able to convert the NIR back to UV light (up-conversion) to effectively activate the genes in the way desired - by controlling the amount of proteins expressed each time, when this should take place, as well as how long it should take place."

This innovative application of nanoparticles for up-conversion of light reported in various journals before has generated considerable scientific interest.

PhD student Mr Muthu Kumara Gnananasammandhan who is a co-author elaborated that the platform technology can be customised for a wide range of applications such as in bioimaging where the nanoparticles can be "labelled" with biomarkers, which will then attach to cancer cells to enable clearer imaging of tumours.

The new method has worked in mice to inhibit cancer growth and the group is currently working with researchers at the National Cancer Centre Singapore to assess the safety and effectiveness. This will pave the way for pilot clinical trials of specific cancers such as skin and nasal cancers. Other projects include using the nanoparticles to develop diagnostic kits for rapid detection of bacteria and biomarkers.