NIST - DNA & Quantum dots glitter without Gold

An innovative team of researchers from the National Institute of Standards and Technology (NIST) have demonstrated that by bringing Gold nanoparticles (AuNPs) closer to the dots and thereafter employing a DNA template to control the distances, then it can assist in either increasing or decreasing the fluorescence of the quantum dots.  It is claimed such a breakthrough opens a potential path for employing quantum dots as a crucial component to better photo-detectors, chemical sensors and nano-scale lasers.

For instance anyone who has tried to tune a radio knows the difficultly when moving their hands toward or away from the antenna can either improve or ruin the resultant reception.  Though such reasons are well documented - controlling the 'strange' effect is much more difficult.  Of a similar nature nanotechnology researchers have long been frustrated in trying to control light emitted via quantum dots, which can easily brighten or dim based on the proximity of other particles.

However, the NIST team have developed means to accurately and precisely place different kind of nanoparticles nearby each other and still be able to measure the behavior of the resulting nano-scale constructs.  Typically nanoparticle based inventions require multiple types of particles to work together, whereby it is critical to have reliable methods to assemble them and subsequently understand how they interact.  In their study - the NIST researchers examined two type of nanoparticles:-

  • Quantum dots - they 'glow' with fluorescent light when illuminated
  • AuNPs - traditionally been known to enhance the intensity of light around themDCN Corp - The National Institute of Standards and Technology (NIST) team explored the reaction of quantum dots and gold nanoparticles (AuNP) placed in different configurations on small rectangular constructs made of self-assembled DNA (see inset for photograph). Laser light (green) allowed the team to explore changes in the fluorescent lifetime of the quantum dots when close to AuNPs of different sizes. Credit - NIST

Both can work in tandem to create nano-scale sensors by employing rectangles of woven DNA strands - assembled by a technique called "DNA origami".  Such DNA rectangles can be smartly engineered to capture different types of nanoparticles at specific locations with a precision of about one nanometer (nm).  Minimal changes in the distance between a quantum dot and AuNPs near one another on the rectangle can result in the quantum dot to either glow more or less brightly as movement is made to and forth from the Au.  The small movements can be detected by 'tracking' the changes in the quantum dots brightness, which could be utilised to reveal the presence of a particular chemical that is selectively attached to the DNA rectangle.  Ensuring the aforementioned hypothesis works properly is complicated - as stated by Alex Liddle, a scientist with the NIST Center for Nano-scale Science and Technology.

Liddle continues to state:-

  • A quantum dot is highly sensitive to the distance between it and the Au, as well as that size, number and arrangement of the AuNPs
  • These factors can boost its fluorescence, mask it or change how long its glow lasts.  We wanted a way to measure these effects, which had never been done before

During their Proof-of-Principle (PoP) research - Liddle et al. had synthesised several groups of DNA rectangles each with a different configuration of quantum dots and AuNPs in a solution.  Thereafter a laser was employed as a spotlight, whereby the team is able to follow the movement of individual DNA rectangles in the liquid, and enable the detection of changes in the fluorescent lifetime of the quantum dots when close to AuNPs of different sizes.  In addition, the NIST team demonstrated how they could exactly predict the lifetime of the fluorescence of the quantum dot, which is dependent on the size of the nearby AuNPs.

Though the NIST tracking technique is time consuming - Liddle states the credibility of their results will enable them to smartly engineer the dots to have a specific desired lifetime.  The provisional success of the tracking method could lead to better measurement methods.  In conclusion, Liddle states that "our main goals for the future, are to build better nano-scale sensors using this approach and to develop the meteorology necessary to measure their performance."  Original article available here.

DCN Corp believes the NIST research is very exciting - especially when considering the future direction of radio tune-ability and its coupling with nano-plasmonics/photonics.  The possibility that DCN Corp can homogeneously dip coat any given nanomaterial and/or nano composite solution - means the resultant effect on the quantum dots could be of a greater controlling factor onto its resultant fluorescence and/or dimness.  Therefore, if you or your colleagues are interested in making the above a reality - please ensure to contact the company as soon as practicably possible.