The sensing performance of the DNA nanodevice can be activated at desired time with a remotely applied NIR light. (Credit: Lele Li/National Center for Nanoscience and Technology.)Researchers have devised a DNA nanodevice that can be turned on remotely using near-infrared (NIR) light inside living cells [Zhao et al., J. Am. Chem. Soc. (2018), DOI: 10.1021/jacs.7b11161].
Biosensors, which are widely used to detect and diagnose disease or study complex biological systems, traditionally employ an ‘always active’ approach whereby devices are ‘off’ until they encounter their target, which turns them ‘on’. But biosensors can be accidentally turned on during delivery, before reaching the desired location, giving false or misleading information.
So researchers from the National Center for Nanoscience and Technology in China, Hunan University, and the University of Illinois at Urbana-Champaign have designed a new sensing strategy that enables targets to be tracked and imaged in vitro and in vivo with high accuracy both spatially and temporally.
The nanodevice is made up of two components: an ultraviolet (UV) light-activated DNA aptamer probe on the surface of lanthanide-doped upconversion nanoparticles (UCNPs). The DNA aptamer probe plays a key role in the process. The DNA in the probe contains a photocleavable (PC) group, which inhibits the binding activity of the aptamer. In practice, this means that when the device is exposed to UV light, the PC group decomposes, restoring the aptamer’s binding capability. The nanoparticles act as a nanoscale transducer, absorbing externally applied NIR light and transforming it to UV, which triggers the decomposition of the PC group.
“[This] leads to a remotely activated DNA nanodevice in the deep-tissue penetrable NIR window,” explains Lele Li, who led the effort at the National Center for Nanoscience and Technology. “Without NIR-activation, the nanodevices do not work even if they meet ATP.”
The use of NIR as the activating factor is important for biomedical applications because UV light can be damaging to cells and tissues.
“Our system allows the use of NIR light as an external regulatory tool, which is much more desirable than UV light because it causes less photodamage and allows deeper penetration for remote activation with relatively high precision,” explains Li.
The researchers believe that the new nanodevice will be useful for manipulating biological functions in vivo, because of its high spatiotemporal resolution, as well as sensing applications. The availability of different aptamers promises that the DNA nanodevice platform could be tailored to detect many targets from small molecules and proteins to cells.
“We now plan to explore the DNA nanodevice design for remotely controlled sensing and imaging in complex biological environments, such as tumors,” Li says.
It will be interesting to see what analytes the platform is suitable for and in what diseases it can be helpful, points out Daniel Kohane of Boston Children’s Hospital at Harvard Medical School.
“This is a potentially important advance in intracellular detection technologies,” he told Nano Today. “It will also be important to see whether the irradiances and irradiation times used will allow detection at greater tissue depth in humans.”
This article was originally published in Nano Today 19 (2018) 3.