Look both ways for new bio-logic

The particles consist of linked silica and polymer-based nanospheres containing tuneable ‘mesopores’ within the 3 to 50 nanometre range. This allows access to each sphere for chemicals ranging from small molecules to large proteins and enzymes, depending on the pore sizes and structures. Since they have different structures on each side, they are called Janus materials after the Greek mythologic god, whose opposing faces looked towards the past and the future.

“Such delicate control of nanoscale morphology and mesoporous structure has never been achieved before,” says nanotechnologist, Xiaomin Li, of Fudan University, China.

This unprecedented control is achieved by making the nanoparticles in a different way from traditional procedures, especially by using an oily emulsion to control the assembly. Traditional methods of incremental assembly tend to yield only single-component structures, or multi-component ones with pores in only one part.

One crucial step towards innovative functions was to demonstrate that the nanoparticles can carry and release different chemical loads in each sphere, determined by the pore size and structure.

“Our systems have great potential to be used as smart drug delivery platforms [that] can recognize a disease site and release the loaded drug only when arriving at the right place,” says Li.

Proof-of-concept work demonstrated that one part of the structures can receive molecular input signals, leading the other part to release an output signal after appropriate processing of the input by molecules carried within the nanoparticle. This allows three key functions of computing logic gates: YES (output in response to a specific input), AND (output occurs when several inputs are all present) and OR (output occurs when any of alternative inputs are present).

“[The] new synthesis technologies and methods make breakthroughs in the construction of biomimetic logic gate systems, which have broad value in the fields of materials, chemistry, and biology,” says nanoscientist, Yuliang Zhao, at the National Center for Nanoscience and Technology in China, who was not involved in the work.

The researchers are now considering the journey towards commercial use. “This is a difficult road,” Li concedes, “as scaling up synthesis, cost accounting, clinical trials, and other aspects are all challenging, but we are on the way towards industrial applications.”

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