The findings will be presented by lead researcher Ingrid Wilke, assistant professor of physics at Rensselaer, at the World of Photonics Congress in Munich, Germany on June 20, 2007. The research originally appeared in the April 2007 edition of Physical Review E.
Human illness begins and advances at the cellular level. Understanding how materials like proteins or drug ingredients affect an individual cell can give researchers important insight into how that material might impact the entire human body, according to Wilke. This makes discoveries at the cellular level extremely important.
The new findings could serve as a set of guidelines for future research that requires precise microinjection of live single cells. Such research ranges from testing drugs for toxicity to targeting tumor cells with chemotherapy.
“The technique will allow researchers to use unprecedented precision to microinject cells or even perform nanosurgery on cells,” Wilke said.
“The problem with previous methods of single-cell injection was low cell viability and low efficacy,” Wilke said. Other physical microinjection methods are greatly hindered in living cells by the natural protective shield encasing mammalian cells. Breaking through this strong, microscopic fortress while still keeping the cell alive and undamaged has proven extremely difficult.
The researchers used tightly focused femtosecond laser beam pulses that created a pore or opening in the cellular wall of living cells and encouraged the cell to take in different molecules. The laser beam serves as a “needle” that punctures the protective skin around the cell, encouraging the cell to take up the material surrounding it. In this case, the researchers used a yellow iodine dye as their nanoscale “vaccine” so the injection results could be easily viewed in microscopic images.
A femtosecond is one billionth of one millionth of a second. The pulse from a femtosecond laser is so fast that it appears as a constant beam of light to the naked eye. The lasers emit radiation in the near-infrared (NIR) portion of the spectrum, meaning that the wavelength is too long to be seen by human eyes.
Upon analysis, the femtosecond NIR lasers were found to preserve the integrity of the cells, Wilke said. But only up to a certain intensity.
“The connections between laser intensity and the rate of injection had not been previously explored in-depth,” Wilke said. “We found that the size of the pores was highly dependent on the intensity of the laser. By modifying the strength of the laser, we could encourage the cell to uptake as little or as much of the materials as we desired. We also determined the intensity at which the cell could first be permeated and the level at which to would be disintegrated.”
The researchers first microinjected living bovine aortic cells. They were able to create different sized pores within the cells that would remain open while the laser continued to pulse and close after the laser beam was stopped.
They later expanded the experiment to include clam eggs (Spisula solidissima oocytes). This form of microinjection is particularly important for cells that are resistant to any other forms of physical microinjection due to an extremely tough cellular membrane, Wilke said. The team also was able to microinject the clam eggs using the femtosecond NIR pulses.
The research discovered that cells were permeated at laser intensities of 4 terawatts per square centimeter. The pore size grew larger as the intensity increased. When the intensity reached more than 35 terawatts per square centimeter, the cellular structure disintegrated and the cell was no longer viable.
“For the first time, we have shown a relationship between pore characteristics and laser beam intensity,” Wilke said. This level of control has not been previously quantified and Wilke says it will allow better regulation of the concentrations of molecules injected into cells.
Gabrielle DeMarco | EurekAlert!
Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory
SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences