Nanodevices built with DNA origami

Did you know DNA could be used for origami?

Not actual DNA origami.

Not actual DNA origami.

The precise control and organization of nanoscale devices has shown a great potential for ultimately creating “nano-devices” that can perform nanoscale biological measurements, deliver medicine in vivo, among many other applications. A recent article from Carlos E. Castro and colleauges from The Ohio State University demonstrates the use of DNA origami with programmable complex and reversible 1D, 2D and 3D motions.

By varying the DNA origami design, they were able to observe different mechanisms for the DNA origami’s 3D motion such as the crank-slider and four bar mechanism. The research team mainly utilized transmission electron microscopy (TEM) to follow the morphology changes as the origami moves.

DNAUsing a fluorescence quenching assay (attaching a fluorescent label on one arm and a quencher on the other), they have characterized the timescale of DNA origami motion. Overall, their group sees this technology as a “foundation for developing and characterizing a library of tunable DNA origami kinematic joints and using them in more complex controllable mechanisms similar to macroscopic machines, such as manipulators to control chemical reactions, transport biomolecules, or assemble nanoscale components in real time.”


Shown below are some of the videos showing the motions of the DNA origami that they have reported:

About the author: Herdeline Ann M. Ardoña is a third year graduate student at Johns Hopkins University Department of Chemistry, currently working in chemistry professor J.D. Tovar’s lab and co-advised by professor Hai-Quan Mao, in materials science and engineering.

Reference: Programmable motion of DNA origami mechanisms. (Proc. Natl. Acad. Sci. U.S.A., 2015, 112, 713-718)

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Science and gender inequality still pressing issue

The issue about gender inequality in science has been an ongoing topic of discussion both in industry and academia. It seems ironic that this field, where objectivity is more often sought over subjectivity, apparently suffers from a gender-biased culture. In line with this, I recently read this blog that featured a number of female scientists and their stories behind how “being a woman” influenced their careers. It’s quite long, but I think the details are quite substantial so I’d say it is worth reading.

At the beginning of Pollack’s article, she mentioned a study conducted just this summer showing how there is still some preference for men (over women) in academic job offerings. I wish she could have included a reference to the paper so that people could see how this study was conducted or how reliable the results are. Overall, her article articulates how these collection of anecdotes from the female scientists she interviewed shows that there are still some stereotypes and social constructs that can potentially be hindrances to females pursuing this field. It’s quite bothering how, from Marie Curie’s time until now, we still haven’t achieved a gender balance—men still outnumbers women in this field.


Marie Curie is in the bottom row, third from left. The only female who attended the Solvay Conference on Physics, 1927. Taken from

I’d say that in this article, the most striking statement for me is: “And yet, as I listened to these four young women laugh at the stereotypes and fears that had discouraged so many others, I was heartened that even these few had made this far, that theirs will be the faces the next generation grows up imagining when they think of a female scientist.” I’m sure there’s more modern female scientists with interesting stories of success than the list that Pollack gave in her article; there should be.

Another interesting article, released earlier this year in Nature magazine, touched on some of the reasons behind this gender imbalance. To note, the article is entitled ‘Science for all’, which I think is more politically correct rather than specifically saying ‘women for science.’ Childcare, political influences and institutional support are some of the issues that the author touched upon.

In the end, the article boils down to showing how women themselves should find ways and implement things on how their ‘status and profile’ can be uplifted in this very competitive field. By looking at more articles/blogs regarding these topics, everything says the gender issue is definitely still present and that the biases still negatively affect females. Different point of views are given, I’d say my fellow female scientists should take some time to look at these and ponder on them.

At this point, I don’t think I am credible enough to throw in my insights about this topic. I haven’t arrived at that point yet in my career that I needed to apply and compete with a pool of male and female applicants for a real job. I guess I feel like I do not have enough experience yet to give a stand about this issue. However, I keep on seeing articles like this for almost a year and a half of my stay here in this institution and from a student’s point of view, I’d say it is somehow discouraging. I suspect other female graduate students feel the same way, at some point.

Having said that, I am writing this not to discourage further but rather to put up a challenge. Statistics are very clear in showing how females are a minority in the field of science. But, I think the initiative to promote balance should come from the female members of this field themselves. This should be the challenge—starting to uplift the status of women in science in an active way and not just passively waiting for opportunities or help to come. These are just some of my thoughts that I hope would be able to stimulate the thoughts of the readers to not just ponder on it, but to provide an action on this issue.

Herdeline Ann Ardoña is a second year graduate student in the Department of Chemistry under Professor J.D. Tovar, co-advised by Professor Hai-Quan Mao.


What does this do? Atomic force microscropy

Several high resolution imaging techniques have been used over vastly diverse disciplines in science and engineering—from microscale with our light microscope to nanoscale with electron- or X-ray beam-mediated imaging techniques. These have been considered as routine laboratory techniques in order to visualize the micro- to nano-scale features of a certain material. How about seeing an actual bond?

AFM, or atomic force microscopy, have been recently been making news in the scientific community as it was used by two different groups to image actual bonds. This microscopic technique is based on a scanning probe, a cantilever with a tip. The tip is lowered closer to the surface of the sample until the forces between the tip to the surface are enough to cause a deflection in the cantilever, which is then correlated to a ‘signal’ that is processed to construct the image of the surface. It runs in either contact or non-contact mode, depending on the characteristics of the sample to be analyzed.

Just a month ago, researchers from China’s National Center for Nanoscience and Technology have published AFM images showing the first image of hydrogen bonds. The image was for 8-hydroxyquinoline, deposited on a copper surface. This is definitely groundbreaking, as this is showing that these bonds with weaker interactions than covalent bonds can also be visualized using this technique. This proves that AFM can be used as a tool to characterize submolecular features.


Earlier this year, another group at the University of California Berkeley have also used AFM in order to monitor a reaction. The group used oligo-(phenylene-1,2-ethynylene), immobilized the molecule on a silver substrate, and monitored the products upon heating. As a routine, organic chemists typically monitor a reaction just by thin layer chromatography (TLC), looking at how the spots develop in the plates over time. Imagine if this technique becomes a routine tool for synthetic chemists, just like NMR or MS— without a doubt, it would definitely revolutionize the way we confirm products by seeing actual bond forming and breaking.








The field seems to be more and more exciting, and maybe we just have to wait for another groundbreaking AFM news before the year ends. Given how direct and informative the images are that we can take from this technique, hopefully, researchers will be able to find a way to make it as a routine synthetic characterization tool someday. This will not only help synthetic chemists, but also materials scientists and other researchers that delve on nanotechnology.

Here’s the link to the papers, for reference:

Herdeline Ann Ardoña is a second year graduate student in the Department of Chemistry under Professor J.D. Tovar, co-advised by Professor Hai-Quan Mao.