Maximizing conversion of electrical current into light output, and efficiently dissipating any residual heat, are design hallmarks of Lumencor’s solid state illumination technology. This has significant consequences for the liquid light guides used to couple light output into microscopes and other bioanalytical instruments. Repeated heating and cooling of liquid light guides can eventually lead to deterioration and lower light throughput.
Thermal image of liquid light guide tips immediately after removal from white light source output ports following running for 30 minutes at 100% output. The temperature markings indicated by the red and blue crosses show the highest and lowest temperature locations in the image ﬁeld.
Thermal imaging effectively demonstrates that a liquid light guide connected to a SOLA SE 365 light engine® undergoes minimal heating under normal operating conditions compared to a light guide coupled to an incandescent metal halide light source. So, not only does the SOLA light engine last longer, its liquid light guide does, too. Like other high-performance optical components, liquid light guides require careful handling. For extra protection against accidental damage, we have recently added a 3 mm-diameter liquid light guide with a stainless steel outer jacket (10-10589) to our range of light engine accessories.
Many microscopy core laboratory managers still spend more time than they would like to on the onerous task of replacing mercury bulbs. Furthermore, as shown in the table below, the time and material costs of frequent bulb replacements can make a sizable dent in the facility’s annual operating budget.
Replacing a mercury source with a SOLA SM light engine® will not only bring an end to bulb replacement chores, but in just over two years, the modest capital investment will have been recouped in saved operating costs. And the SOLA SM light engine will still have about 80% of its 20,000–hour design lifetime left to run. It’s an excellent investment in a brighter future.
Many applications in life sciences and beyond benefit from the integration of spectral, temporal and spatial control of light output provided by Lumencor light engines®. A glance at some recent research publications provides insight into the diversity of these applications.
Optogenetics: Not Just for Neurons
Although optogenetic stimulation and inhibition are most often used to modulate neuronal function, there are emerging applications in other areas of biomedical research as well. Here are three examples:
1. Protein–protein interactions
Researchers from Stanford University described the use of Arabidopsis thaliana cryptochrome 2 (CRY2) photodimerization with its partner protein CIB1 to control the kinesin-mediated intracellular distribution of mitochondria, peroxisomes and lysosomes. CRY2–CIB1 dimerization was initiated using 200-ms light pulses from a SOLA SE Light Engine®.
2. Developmental biology
Mutations in genes encoding potassium channels expressed during embryonic development result in anomalous craniofacial morphogenesis. Adams and co-workers used optogenetic stimulation and inhibition of transmembrane potassium flux driven by a SPECTRA light engine® to demonstrate that the spatial distribution of membrane potentials ultimately controls the development of craniofacial anomalies in Xenopus embryos.
3. Calcium signaling
Researchers at the University of Pennsylvania describe optogenetic control of calcium oscillations in HeLa cells via expression of the photosensitive G protein-coupled receptor melanopsin. They used a SPECTRA X light engine® for photostimulation of melanopsin at 470 nm and also for excitation of the intracellular Ca2+ indicator X-rhod-1 at 570 nm.
Expansion microscopy (ExM) is a new technique that enables super-resolution microscopy with conventional widefield microscopes by physically expanding the specimen, bringing sub-resolution structures into the diffraction limited resolution range. Boyden and co-workers used a SPECTRA X light engine for validation of ExM on cells and tissues with multicolor immunofluorescence and fluorescent protein labeling.
Intraoperative 5-aminolevulinic acid (ALA)-induced protoporphyrin IX fluorescence imaging provides margin definition to guide the surgical removal of tumors. However, the measured fluorescence signal is distorted by light scattering and tissue autofluorescence, potentially compromising complete tumor excision. Sibai and co-workers describe implementation of spatial frequency domain imaging (SFDI) using structured illumination from a SPECTRA X light engine coupled to a digital micromirror device (DMD) to generate spectral maps of tissue optical properties, which are then applied on a pixel-by-pixel basis to correct the measured fluorescence image.
Artificial photosynthesis is the process of converting sunlight into fuels by photochemical splitting of water into oxygen and hydrogen or reduction of CO2 to carbon-based fuels. In pursuit of this objective, dye-sensitized photoelectrosynthesis cells (DSPEC), in which a wide band-gap, nanoparticle oxide film, typically TiO2, is derivatized with surface-bound molecular assemblies for light absorption and catalysis are currently under active development. Researchers from the University of North Carolina at Chapel Hill recently described a second-generation DSPEC that achieves greatly enhanced visible-light–driven water splitting efficiencies. Performance evaluation was carried out using 445 nm light output from a SPECTRA light engine.