Microscope Lens Inspired by Lighthouses Makes It Easier to Observe Molecular-Level Details of Biological Processes

The thin and cost-effective lens is 3D printed and has the capacity to put live cells under the microscope, which would significantly improve diagnostics.
Credit: © 2020 KAUST; Andrea Bertoncini

Custom-fabricated lenses make it easy to attach high-tech microscopes directly to cell incubators.

An optical device that resembles a miniaturized lighthouse lens can make it easier to peer into Petri dishes and observe molecular-level details of biological processes, including cancer cell growth. Developed by KAUST, the new lens is also very cost effective.

Many bioimaging techniques require fluorescent dyes to be added to specific cell targets. But a recently developed method known as stimulated raman scattering (SRS) microscopy can avoid cumbersome labeling steps by using laser pulses to collect molecular vibrational signals from biological samples. The ability of SRS microscopes to produce high-resolution, noninvasive images at real-time speeds has prompted researchers to deploy them also for in vivo disease diagnostic studies.

KAUST researchers have developed an ultrathin lens that fits into the stage-top incubators that are used to grow live cells for bioimaging.
Credit: © 2020 KAUST

One drawback of SRS microscopes, however, is that the detection system is affected by a background signal, known as cross-phase modulation, which is generated by the intense interactions between laser pulses and the samples.

“This background signal is ubiquitous and reduces the contrast during microscopic observation of complex samples, such as live cells,” explains Carlo Liberale from KAUST. “It also makes it difficult to identify target molecules.”

To avoid the effects of cross-phase modulation, most SRS microscopes need to use bulky glass objectives capable of collecting wide angles of light. However, these kinds of lenses are nearly impossible to fit into the stage-top incubators that are used to grow live cells for bioimaging.

Andrea Bertoncini, a researcher in Liberale’s group, spearheaded work to create an ultrathin SRS lens using laser-based three-dimensional (3D) printing. Taking their cue from the slender design of lighthouse lenses, the KAUST team printed tiny lens-like and mirror-like features into a transparent polymer only a fraction of a millimeter thick.

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