Chemicals detected with nanoscale chip using bacterial cells

The Jerusalem-based team looked for ways to integrate all system components, including light sources and detectors, on-chip at the nanoscale.

Bacteria (illustrative) (photo credit: REUTERS)
Bacteria (illustrative)
(photo credit: REUTERS)
Hebrew University researchers have created a nanophotonic chip system using lasers and bacteria to observe fluorescence emitted from a single bacterial cell. The novel system, described recently in the journal Nano Letters, paves the way for an efficient and portable on-chip system for diverse cell-based sensing applications, such as detecting chemicals in real time.
To fix the bacteria in place and to route light toward individual bacterial cells, they used V-groove-shaped plasmonic waveguides – tiny aluminum-coated rods only tens of nanometers in diameter.
Plasmonic nanoparticles are particles whose electron density can couple with electromagnetic radiation of wavelengths that are far larger than the particle due to the nature of the interface between the medium and the particles.
The field of on-chip photonic devices for biological and chemical sensing applications presents many powerful alternatives to conventional analytical techniques for applications ranging from “lab on a chip” to environmental monitoring. However, these sensing devices require a cumbersome apparatus, even when measuring only single cells.
The research was led by Prof. Uriel Levy, director of the university’s Harvey Krueger Family Center for Nanoscience and Nanotechnology at in collaboration with Prof.
Shimshon Belkin of HU’s Alexander Silberman Institute of Life Sciences, who genetically engineered the bacterial sensors, and Prof. Anders Kristensen from the Danish Technical University.
The Jerusalem-based team looked for ways to integrate all system components, including light sources and detectors, on-chip at the nanoscale. This would result in a lab-on-chip system that is small, portable and can perform sensing in real time.
To achieve this, they molecularly engineered live bacteria that emit a fluorescent signal in the presence of target compounds. They paired these on-chip with a nanoscale waveguide, which not only served the purpose of guiding light, but also allowed mechanical trapping of individual bacteria within the V-groove.
The system worked well both in wet environments, where the bacteria are flowing on top of the waveguide, and in dry conditions, where the bacteria are trapped within the waveguide.
The results provided a clear indication of the feasibility of constructing a hybrid bioplasmonic system using live cells. Future work will include the construction of a waveguide network, diversifying the system to incorporate different types of bacterial sensors for the detection of various biological or chemical substances whose constituents are identified and measured.
HOW MUSICIANS CRAFT THEIR NEXT CHART-TOPPER People like to say that mainstream music all tends to sound the same. While this is true to an extent, an analysis of more than 26,000 songs by researchers at the European Institute of Business Administration and Columbia Business School shows that breakout songs – the songs that hit the very top of the charts – are those that conform to current musical preferences while infusing a modicum of individuality.
Prof. Noah Askin and Prof. Michael Mauskapf at Columbia analyzed the acoustic attributes of more than 26,000 songs that appear on Billboard’s Hot 100 from its beginning in 1958 to 2016.
Data on 11 acoustic features, such as a song’s key, mode and tempo, were collected. In a recently published paper in the American Sociological Review, the researchers showed that hitting the top of the charts involves finding the right balance between familiarity and novelty.
“The songs that reach the highest echelons of the charts bear some similarity to other popular songs that are out at the same time, but they must be unique in certain ways in order to differentiate themselves,” said Askin. “Adele’s songs are great examples of the perfect typicality: she has been tremendously successful with that little bit of differentiation.”
Mauskapf added, “There’s a perception in the industry that top songs can be reverse-engineered based on what audiences are more likely to listen to or buy. But our findings show that ‘hit song science’ will get an artist only so far. It’s very difficult to predict what kinds of songs other musicians will release and when audiences will find them to be optimally distinct.”
The study accounted for elements that could account for a song’s chart performance, such as the artist’s previous success or the prominence of their record label.
It also took into account artists’ unique characteristics (such as their star factor and style), their labels’ marketing budgets, and the prevailing competition, which all play a part in pop culture.
Analyzing the data with these considerations in place, the researchers devised a “typicality” score to compare the acoustic footprint of each song to that of all the songs that appeared on the charts in the year prior to its release. This score essentially captures how much a given song sounds like its peers.
“We found that songs with a somewhat below average typicality score tended do better on the Hot 100. To have the best chance of reaching the very top of the charts, a song needs to stand out from its competition, but not so much as to alienate listeners,” said Mauskapf.
The authors believe the study also has implications for popular culture more generally, as well as the success of innovations. Up to this point, scholars have established that the success of cultural products rests heavily on a variety of factors including marketing budgets, producers’ prior success, the context of the release and relative genre popularity. Askin and Mauskapf’s study looks at an under-researched element in this equation – how the cultural content of the product positions it for success – and finds the importance of balancing novelty and familiarity.
“What becomes popular next is likely to be slightly differentiated from the last round of hits, leading to a constant evolution of what is popular. Popularity is a moving target, but the context always remains relevant. This is at least as much art as it is science,” said Askin.