Gene therapy is a relatively new way to treat a range of diseases, from inherited disorders to cancers. The technique involves introducing foreign genetic material into host cells to help abnormal genes function normally again, or to provide additional biological functions to existing healthy genes. However, progress in the field has been difficult for lack of safe delivery methods.

Non-toxic nanodiamonds
There are two main approaches to gene delivery: viral and non-viral. The viral technique is currently favoured because viruses can efficiently infect cells – they have evolved to do just this. But, it is also dangerous and has led to cancer, and even death, in some cases.

Non-viral vectors, on the other hand, such as certain types of polymers, have been shown to be less toxic, but they are also less efficient at entering cells. This is where nanocarriers like nanodiamonds could come in. Since these materials can be dispersed in water, they are stable and can readily enter cells. And, unlike other nanomaterials that cause cell inflammation, they are not toxic.

Dean Ho of Northwestern University and colleagues have now shown that modifying nanodiamond surfaces with polyethyleneimine 800 (PEI800) – a commercially available polymer commonly used in gene delivery – enhances gene delivery into cells by 70 times compared to using PEI800 alone. The scientists used a green fluorescent protein-coding DNA sequence to demonstrate how genes could successfully be delivered into the cells. When introduced in particle form, the nanodiamond-PEI800-DNA complexes produce genetic changes that make the cells fluoresce. This indicates that gene delivery has taken place.

“Nanodiamonds possess several beneficial properties, including scalable processing, biocompatibility and the ability to deliver nearly any type of therapeutic (for example, small molecules, nucleic acid and proteins),” Ho told “Their surface properties can also be modified with polymers such as PEI800 and a range of DNA sequences for treating a variety of conditions.”

The team is now developing multifunctional nanodiamonds that can carry several therapeutics, imaging and target agents, among other components, in a single system. “There are still many challenges to overcome before we reach pre-clinical trails, but the nanodiamond properties we have observed serve as a promising foundation,” said Ho.

The work was published in ACS Nano.