M squared lasers

LASERS COME UNDER THE MICROSCOPE

Many bio-medical research, medical diagnosis, and medical treatment methodologies rely on probing and/or modifying the biological system being studied. Given the precision nature of laser beams, their power, and the ability to tune the wavelength of laser light to be either strongly or weakly absorbed by biological tissue, it is no surprise that laser sources are finding a wealth of applications in the bio-medical arena. And while laser source innovation is providing new ways forward in bio-medical applications, product reliability is particularly critical in this application area.

Examples of lasers contributing strongly to bio-photonics include:

Breath analysis

Human breath is teeming with bio-molecules that can reveal the presence or absence of certain diseases or metabolic processes. Since these molecules exhibit distinct absorption characteristics, particularly at the infrared wavelengths generated by M Squared's 'Firefly-IR' laser, they can be detected by infrared laser spectroscopic methods. This provides the potential for non-invasive methods of health screening for a wide variety of medical conditions, including detecting the presence of cancer, monitoring respiratory diseases, assessing liver and kidney function, and determining exposure to toxins.

Multi-photon and CARS microscopy

By focusing the intense beam from a near-infrared ultrafast laser, such as the M Squared 'Sprite', into a biological sample under a microscope, a multi-photon excitation occurs when two (or more) photons, whose summed energy is sufficient to excite a biological fluorophore, arrive simultaneously. By collecting the multi-photon excitation and scanning the beam across the sample, an image of the sample can be produced, all without needing to stain the sample with toxic dyes. The use of near infrared light to excite a fluorophore in the visible range allows multi-photon microscopy to image deeper within tissue than confocal microscopy with visible light. Additionally, since the excitation signal is spatially confined to the focal plane of the objective, it eliminates the necessity for a confocal pinhole to generate optically sectioned images, which greatly improves detection sensitivity. The spatial confinement of signal generation also reduces overall photobleaching of the sample. These advantages make multi-photon microscopy the ideal choice for imaging deep within live and/or thick, highly light scattering tissue over long periods of time. If the beams from two ultrafast lasers are synchronised to arrive at a sample at precisely the same location and time, and the wavelengths of the two sources are detuned appropriately, a Coherent Anti-Stokes Raman signal can be excited, also allowing structural information of the sample to be assessed and imaged.

Photoporation

The introduction of membrane impermeable substances such as foreign DNA into a biological cell (transfection) is a ubiquitous problem in cell biology. This technique is particularly challenging when it is desirable to target specific cells for treatment. Laser-assisted cell poration, or 'photoporation', offers the distinct advantage of such cell specificity while maintaining high transfection efficiency, good post-transfection cell viability and overall ease of operation. In the technique of photoporation, a laser beam is typically focused through a high numerical aperture microscope objective lens onto the outer membrane of the targeted cell. The high peak power and lack of heat deposition into the sample provided by femtosecond lasers such as M Squared's 'Sprite' make ultrafast lasers ideally suited to the photoporation technique.

Application advances often demand the development of new laser systems with new performance capabilities. Historically, however, innovation in commercial laser systems has all too often come at the expense of ease of use and reliability, with open-lid product designs that require frequent operator adjustments and maintenance, in marked contrast to the hands-off sources needed for bio-photonics.

With a 20-year design and applications perspective, M Squared's goal is Dependable Innovation, which describes our commitment to sealed, maintenance-free, automated laser systems that provide next-generation, breakthrough performance for bio-photonics and myriad other applications.