Nov. 11, 2024
Fluorescence Microscopy
Advancing LED (illumination) technology and multi-bandpass filters are combining to provide more opportunities than ever for the development of sophisticated fluorescence instruments, including for fluorescence microscopes. System designers and end-users are leveraging new potential in fluorescence techniques and instrumentation as a result: The simplicity, cost-efficiency, and durability of basic devices is now converging with versatility of more advanced systems. This article provides background information about why multiple wavelength bands are often needed when dealing with multiple fluorophores; a description of how current solutions are implemented using broadband lamps and filter wheels or replaceable filters, and the limitations this imposes; and a description of an approaching using LEDs and multi-band filters in tandem, and the benefits for users of fluorescence microscopes. The article also provides a look at current trends in fluorescence instrumentation, made possible through the availability of “any-color” LEDs and advanced optical filter technology.
Key Technologies: Multi-bandpass optical filters, fluorescence microscopy, fluorescence imaging, visible high-brightness LEDs, bio-imaging
NIR Spectroscopy
Research on extracted human teeth can sometimes be hampered by the presence of restorative materials, decay or other abnormalities. This is especially true for studies investigating attributes other than decay, which may require large numbers of sound teeth. In Rockhampton, Australia’s beef capital, a dental research project used readily available bovine teeth to explore near-infrared (NIR) spectroscopy for characterizing dental properties. Human and bovine teeth primarily consist of enamel, dentine, and cementum. Hydroxyapatite (HAp) is the main mineral responsible for tooth strength, but it is highly susceptible to the influence of environmental factors. NIR spectroscopy, with lower absorptivity than infrared (IR), allows for a greater optical sampling volume of the tooth. NIR reflectance spectra of labial tooth surfaces successfully differentiated bovine teeth by sex, diet, and, in some cases, geographic origin. Studies on human teeth revealed differentiation between vital and non-vital teeth, highlighting spectral differences linked to moisture content and porosity. Importantly, the study also differentiated teeth from older and younger individuals, also related to moisture content and porosity, which may have potential forensic applications. A Partial Least Squares Regression model was developed for assessing tooth moisture content, offering a non-invasive method for characterizing dental health and providing valuable insights into clinical conditions and provenance information.
Key Technologies: Near-infrared spectroscopy, dental imaging, infrared absorption, chemometrics
Terahertz Imaging
Due to the depth pulses can reach in the terahertz range (wavelength 3 mm-30 µm), it has long shown promise for biological research and medical imaging, given its relatively low photon count makes it safer for subjects than x-rays. It is already used routinely for product and security inspections. But THz has been traditionally limited by its low spatial resolution that is inadequate for cellular imaging, as well as its strong absorption in water, limiting its clinical use to studies of hydration in healing or damaged tissue, for example. But researchers have enhanced the reach of terahertz imaging through pump-probe spectroscopic systems, as well as specialized components like photoconductive antennas and nonlinear photonic crystals to guide the pulses and capture temporal and spatial information. And recent work has tried to exploit the terahertz’s strong absorption in water, by studying the relaxation dynamics in the hydration layers bound to biomolecules, which can tell significant attributes about the molecules themselves. But the most successful approach seems to be to unite terahertz imaging with other approaches to magnify (sometimes literally) its impact, such as near-field microscopy and various time-domain methods, which has been useful in identifying specific types of cancer, as well as osteoarthritis.
Key Technologies: Terahertz imaging, time-domain terahertz spectroscopy, cancer imaging
LED illumination
LEDs are now the go-to microscopy illumination technology of choice for widefield fluorescence, due to many reasons from performance to ease of use and sustainability. In the context of automated fluorescence systems such as high content screening platforms, spatial biology instruments and semiconductor inspection devices, the function of the light source can seem relatively simple: provide a focused beam of light at a specified wavelength. However, there are many aspects to consider when it comes to designing a high-performance LED illumination system. This article provides a closer look at the importance of precision, performance and lifetime – and how these can be maximized. We also explain which aspects of the light source can be customized to suit individual application requirements, helping guide system designers towards optimized illumination.
Key Technologies: LEDs, illumination, fluorescence, microscopy
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