Simplified method for calibrating optical tweezers: Broadband measurement of viscoelasticity with reduced measurement time

Measurements of biomechanical properties inside dwelling cells require minimally invasive strategies. Optical tweezers are notably enticing as a software. It makes use of the momentum of sunshine to lure and manipulate micro- or nanoscale particles. A staff of researchers led by Prof. Dr. Cornelia Denz from the College of Münster (Germany) has now developed a simplified methodology to carry out the required calibration of the optical tweezers within the system below investigation. Scientists from the College of Pavia in Italy have been additionally concerned. The outcomes of the research have been revealed within the journal Scientific Studies.

The calibration ensures that measurements of various samples and with totally different units are comparable. One of the crucial promising strategies for calibrating optical tweezers in a viscoelastic medium is the so-called active-passive calibration. This includes figuring out the deformability of the pattern below investigation and the power of the optical tweezers. The analysis staff has now additional improved this methodology in order that the measurement time is lowered to just some seconds. The optimized methodology thus presents the opportunity of characterizing dynamic processes of dwelling cells. These can’t be studied with longer measurements as a result of the cells reorganize themselves in the course of the measurement and alter their properties. As well as, the shortening of the measurement time additionally helps to scale back the danger of injury to the organic samples because of light-induced heating.

In simplified phrases, the underlying process to carry out the calibration works as follows: The micro- or nanometer-sized particles are embedded in a viscoelastic pattern held on the stage of a microscope. Speedy and exact nanometer-scale displacements of the specimen stage trigger the optically trapped particle to oscillate. By measuring the refracted laser mild, adjustments within the pattern’s place could be recorded, and on this means, conclusions could be drawn about its properties, corresponding to stiffness. That is normally accomplished sequentially at totally different oscillation frequencies. The staff led by Cornelia Denz and Randhir Kumar, a doctoral scholar within the Münster analysis group, now carried out the measurement at a number of frequencies concurrently for a large frequency vary. This multi-frequency methodology results in a shortened measurement time of some seconds. The scientists used options of methyl cellulose in water at totally different concentrations as samples. These have an identical viscoelasticity to dwelling cells.

Background: Biomechanical properties corresponding to stiffness, viscosity and viscoelasticity of dwelling cells and tissues play a vital position in lots of important mobile features corresponding to cell division, cell migration, cell differentiation and tissue patterning. These properties of dwelling cells may additionally function indicators of illness development. For instance, the onset and growth of most cancers is usually accompanied by adjustments in cell stiffness, viscosity, and viscoelasticity.

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