Light-Activated Tool Controls Protein Bonds and Tracks Cell Adhesion

Optical tools can be used to activate biological functions, but with current methods the effects are slow to appear, and sustained effects require continuous light activation. As a result, these light-activation tools provide limited control of fast biological processes and can lead to toxicity in cells and organisms.

Although light is a well-established tool for control of bond breakage, it is less firmly established for the control of specific bond formation in complex environments.

A team at Tampere University worked with researchers at the University of Cambridge and the University of Pittsburgh to develop a way to use visible light to control irreversible protein binding. The new optical technique for fast, irreversible protein conjugation could be especially valuable in processes where a short initial signal leads to long-term changes in cell or tissue function. Examples include the regulation of gene expression during stem cell differentiation and the activation of immune cells in viral infections.

The researchers built on their previous work with proteins to develop a system for the rapid, light-activated control of protein bond formation. Their “protein superglue” is a peptide/protein pair called SpyTag003/SpyCatcher003 that exhibits fast, irreversible binding. Based on an engineered protein, the SpyTag003/SpyCatcher003 peptide/protein pair allows the modular assembly of complex protein structures.

To achieve optical control of the protein superglue, the researchers looked beyond the 20 amino acids constituting human proteins. Using modified protein synthesis machinery from archaebacteria, they incorporated a light-reactive, unnatural amino acid into the SpyCatcher003 protein to make the protein photoreactive. The amino acid was strategically placed to block the peptide/protein pairing until it was activated by light.

In experiments, the researchers showed a uniform, specific reaction in cell lysate upon light activation.

“A short pulse of light was enough to trigger the rapid and efficient formation of the irreversible peptide/protein complex, both in the test tube and in living cells,” said Mark Howarth, a professor at the University of Cambridge. “Importantly, the activation only took place with specific wavelengths of light, making it possible to combine protein control with live-cell fluorescence microscopy.”

After validating their approach to optically controlling irreversible protein coupling, the researchers applied the technique to the covalent reconstitution of a talin protein that was split in half. The researchers used light to activate the talin — a central adhesion protein — inside living cells.

Optical control of talin reconstitution allowed the researchers to probe the timescale of the initial adhesion complex formation. By tracking the timing of protein recruitment into the adhesion complex, the team could determine a timeline of the events leading to the formation of the adhesion complex, and the hierarchy of the recruitment of key components for cell adhesion.

Cell-matrix adhesions — large protein complexes consisting of hundreds of different proteins — are highly dynamic. “Their dynamic structure and vast complexity make cell adhesions difficult to study,” Tampere University professor Vesa Hytönen said. “The details of how cell-matrix adhesions initially form and how they react to different stimuli have remained largely unknown.”

Researcher Rolle Rahikainen said that the team observed an immediate cell response after activating the talin protein with a short pulse of light. “We got very excited when we first realized how well the system worked in controlling complex cellular processes, such as the formation of adhesion and cell spreading.”

The findings demonstrate the potential of the light-activated protein superglue for investigating complex cellular processes. The results could also lead scientists to a more comprehensive understanding of the complex structure and function of adhesion.

The modular, Lego brick-like structure of the system makes it applicable to the study and control of diverse cellular functions. The precise, irreversible assembly of biological building blocks has many applications, from biomaterials to vaccines.

Beyond adhesion, SpyCatcher003 could be used for the photocontrol of biomolecules. The robust cellular response, initiated in seconds, opens possibilities for spatiotemporal control of highly dynamic intracellular and extracellular processes.

Bio Photonics Research Award

Visit: biophotonicsresearch.com
Nominate Now: https://biophotonicsresearch.com/award-nomination/?ecategory=Awards&rcategory=Awardee

#MeatAnalysis #FluorescenceTech #FoodQuality #FoodSafety #SpectroscopyInFood #MeatAuthentication #RapidDetection #FoodScience #MeatFreshness #MolecularDetection #FoodIndustryInnovation #NonDestructiveTesting #FoodMonitoring #SpectroscopyApplications #QualityControl #AdvancedSpectroscopy #MeatSpoilageDetection #FoodIntegrity #SmartFoodTesting #RealTimeAnalysis #FoodAuthenticity #FoodSafetyInnovation #SpectroscopyResearch #NextGenFoodSafety #InnovativeFoodScience,

Simple Approach to Laser Color Conversion Uses SRS in Ionic Liquids

S

cientists from Brookhaven National Laboratory showed that ionic liquids provide an efficient means to convert one color of laser light into another. The discovery could lead to a way to create lasers with desired colors for a range of medical, scientific, and technological applications.

The method is based on the interaction between the laser and different types of ionic liquids (also known as liquid salts). The vibrational energy in the chemical bonds in the ionic liquid cause the laser’s energy to shift and change color.

“By adding a certain ion that has a particular vibrational frequency, we can design a liquid that shifts the laser light by that vibrational frequency,” chemist James Wishart said. “And if we want a different color, then we can switch out one ion and put in another that has a different vibrational frequency. The component ions can be mixed and matched to shift laser colors by different degrees as needed.”

The new approach to changing laser wavelengths has its roots in a project to boost the capabilities of a CO2 laser at Brookhaven’s Accelerator Test Facility. To improve the laser’s beam quality and repetition rate, the researchers wanted to pump the laser using optical excitation instead of electric discharge.

To create a laser with the appropriate wavelength for optical pumping, the researchers used stimulated Raman scattering (SRS) to shift the wavelength of an existing laser. SRS can be used to harness the vibrational frequencies of molecules in a solid, liquid, or gas form.

“Basically, the laser deposits energy into the molecular vibrations — the squishing and stretching of the chemical bonds that make up the material,” researcher Rotem Kupfer said. “Then the photons (particles of light) that come out have the original energy, minus the energy of those vibrations.” The lower-energy photons have a longer wavelength and, thus, a different color.

The researchers demonstrated that 1-ethyl-3-methylimidazolium dicyanamide (EMIM DCA), an ionic liquid, was an effective medium for converting 532-nm pulses from a Q-switched Nd:YAG laser to 603 nm. This corresponded to an approximate 2200 cm−1 shift, which could be used to generate mid-infrared radiation for optical pumping of CO2 lasers.

While choosing the best ionic liquid for pumping the CO2 laser, the researchers considered that their color-shifting approach could have a broader use.

In a proof-of-principle, single-pass conversion setup, the researchers obtained a threefold-higher Raman conversion efficiency in the ionic liquid compared with water under identical conditions, resulting in an efficient generation of high-quality orange laser pulses in a wavelength region that is difficult to access at high energies.

“There are a lot of hard ways to do Raman shifting. But for this one, we just filled a tube with a properly selected ionic liquid, shot a laser in from one end, and we got the color we wanted out — without any fine tuning,” Wishart said.

Kupfer said that other methods for achieving a shift in laser color require complex optical setups or the use of toxic materials. “Plus, those other processes ‘break’ the molecules; they wear out and have to be replaced,” he said. “In our case, it is a balance sheet. The molecules stay unharmed.”

The researchers determined that ionic liquids provide a framework to engineer liquids suitable for wavelength conversion over a broad spectral range. Careful selection of the molecular structures of the ionic liquid anions and cations lead to specific characteristics, such as a desirable Raman shift, low Brillouin scattering, and good optical transmission in the pump and Stokes wavelengths. An ionic liquid can interact with photons while offering a high density of energy-swapping sites.

Gas molecules have limited vibrational frequencies, and diffuse gaseous molecules mean scattering efficiency is low. Solids have more tightly packed molecules, making them more efficient, but their complex vibrational frequencies make them costly to produce.

“Liquids are somewhere in between,” Wishart said. “You’re still dealing with single molecules, but denser, meaning higher efficiency than gases. And with ionic liquids, you can engineer the molecules to give you the frequency you need.”

The large number of ionic liquids available makes it possible to precisely tune the energy loss caused by the ionic liquid-photon interaction, providing greater selective control over color. Optically transparent ionic liquids prevent background absorption of light. In addition, their viscosity prevents laser scattering from acoustic waves, which can diminish the color-shifting effect in low-viscosity liquids.

Although further improvements could optimize the process, the researchers said that overall, the made-to-order ionic liquids provide a suitable platform for efficient, simple, adjustment-free laser color shifting using SRS.

Bio Photonics Research Award

Visit: biophotonicsresearch.com
Nominate Now: https://biophotonicsresearch.com/award-nomination/?ecategory=Awards&rcategory=Awardee

#MeatAnalysis #FluorescenceTech #FoodQuality #FoodSafety #SpectroscopyInFood #MeatAuthentication #RapidDetection #FoodScience #MeatFreshness #MolecularDetection #FoodIndustryInnovation #NonDestructiveTesting #FoodMonitoring #SpectroscopyApplications #QualityControl #AdvancedSpectroscopy #MeatSpoilageDetection #FoodIntegrity #SmartFoodTesting #RealTimeAnalysis #FoodAuthenticity #FoodSafetyInnovation #SpectroscopyResearch #NextGenFoodSafety #InnovativeFoodScience,

Computational Technique Harnesses the Benefits of Spectral, Photographic Insights

Using an approach that combines computer vision, color science, and optical spectroscopy, researchers at Purdue University devised an approach that enables conventional photography to be used for optical spectroscopy and hyperspectral imaging. Using the mechanism, the researchers realized spectral resolution comparable to the resolution of scientific spectrometers with photos from a smartphone camera.

A range of industries, running the gamut from agriculture, environmental monitoring, and food quality analysis, to industrial quality control, defense and security, and medical diagnostics, could benefit from the technique, according to its developers.

The researchers hypothesized that the RGB values of reference colors, as captured by a traditional camera, could be used to design a spectral color chart that could then be used to decode spectral information. The fidelity of spectral recovery would be determined mainly by the spectral incoherence among the reference colors in the chart.

They developed a general computational framework, co-designed with spectrally incoherent color reference charts, to recover spectral information from a single-shot photograph. They optimized reference color selection and the computational algorithm to eliminate the need for training data or pretrained models.

The spectral color chart, together with the device-informed computation, can be used to recover spectral information from RGB values acquired using conventional cameras, such as smartphone cameras.

In transmission mode, data is acquired by photographing the spectral color chart through the sample of interest. Altered RGB values of reference colors are used to recover the spectral intensity of the sample. In reflection mode, the sample of interest is placed alongside the spectral color chart to recover the sample’s spectral hypercube without needing a hyperspectral imaging system. A spectral hypercube of the sample can be constructed from a single-shot photo, analogous to hyperspectral imaging.

The technique, which the researchers called computational photography spectrometry (CPS), has the potential to make optical spectroscopy and hyperspectral imaging accessible with off-the-shelf smartphones. Instead of limiting the user to multispectral data with only a few bands, the technique enables a high spectral resolution of 1-2 nm.

“Importantly, the spectral resolution — around 1.5 nm — is highly comparable to that of scientific spectrometers and hyperspectral imagers,” researcher Semin Kwon said. “Scientific-grade spectrometers have fine spectral resolution to distinguish narrow spectral features. This is critical in applications like biomedical optics, material analysis, and color science, where even small wavelength shifts can lead to different interpretations.”

Although methods exist to estimate and reconstruct spectral information from RGB values acquired using conventional cameras, they are limited in their ability to achieve a high degree of spectral resolution.

The researchers developed a generalizable method for extracting high-resolution spectral information from a single-shot photo of a sample without having to rely on task-specific training datasets or predetermined models. This provides an advantage over existing machine learning models for spectral reconstruction, which depend on task-specific training data or fixed models.

“From an algorithmic standpoint, to the best of our knowledge, our paper presents the first computational spectrometry method with 1.5-nm spectral resolution using a photograph of an arbitrary sample without relying on specific training data or predetermined algorithms,” professor Young Kim said.

The spectral color chart and device-informed computation eliminate the need for complex hardware, simplifying the hardware requirements for the CPS technique. And, the CPS approach could potentially offer a simple, affordable, portable way to use smartphones for optical spectroscopy and hyperspectral imaging in day-to-day applications.

“Many mobile spectrometers require additional accessories and bulky components as mandatory attachments to smartphones,” Kwon said. “In contrast, our method leverages the built-in camera of the smartphone.”

The team is currently using the algorithm for digital and mobile health applications in both domestic and resource-limited settings.

“Photography is central to these applications, but color distortion has posed a persistent challenge, which is why we are focusing on these settings,” Kim said. “This algorithm provides a basis for quantifying and correcting colors, enhancing the reliability of medical diagnostics.”

The researchers believe that the generalized computational photography spectrometry technique could change how industry uses smartphones.

“A photograph is more than just an image. It contains abundant hyperspectral information,” Kim said. “We are one of the pioneering research groups to integrate computational spectrometry and spectroscopic analyses for biomedical and other applications.”

A patent for the algorithm is pending. Industry partners interested in developing or commercializing the algorithm should contact Patrick Finnerty, assistant director of business development and licensing-life sciences, at Purdue University.

Bio Photonics Research Award

Visit: biophotonicsresearch.com
Nominate Now: https://biophotonicsresearch.com/award-nomination/?ecategory=Awards&rcategory=Awardee

#MeatAnalysis #FluorescenceTech #FoodQuality #FoodSafety #SpectroscopyInFood #MeatAuthentication #RapidDetection #FoodScience #MeatFreshness #MolecularDetection #FoodIndustryInnovation #NonDestructiveTesting #FoodMonitoring #SpectroscopyApplications #QualityControl #AdvancedSpectroscopy #MeatSpoilageDetection #FoodIntegrity #SmartFoodTesting #RealTimeAnalysis #FoodAuthenticity #FoodSafetyInnovation #SpectroscopyResearch #NextGenFoodSafety #InnovativeFoodScience,

Spatial Light Modulation Gauges How Lenses Slow Progress of Myopia

Myopia, or nearsightedness, is one of the most common ocular disorders worldwide and a leading cause of visual impairment in children. Although specialized eyeglass lenses have been clinically tested to treat myopia progression, an in-depth optical characterization of the lenses has not yet been performed.

Researchers from the ZEISS Vision Science Lab at the University of Tübingen and the University of Murcia undertook a comprehensive characterization to investigate the properties of spectacle lenses designed to slow the progress of myopia. The results of their study could help increase the efficacy of future lens designs.

Myopia is typically caused when a person’s eyes become elongated, which affects how the eyes focus on faraway objects. The condition can progress in children and teens as their bodies grow.

To reproduce pupil shape and myopic ocular aberrations, researchers developed an instrument that reproduced the aberrations in myopic eyes and enabled physical simulation of the pupil. They based their instrument on spatial light modulation (SLM) technology.

“After exploring the state of the art, we didn’t find a method that could be used to characterize the optical properties of these eyeglass lenses under real viewing conditions,” said researcher Augusto Arias-Gallego. As a result, Arias-Gallego said, the researchers endeavored to build an instrument that can measure the lens’ optical response to different angles of illumination, while also reproducing the myopic eye’s pupil and refractive errors.

The team’s instrument uses an illumination source mounted on an arm that rotates around the lens. After the light passes through the lens, it is guided to an SLM by a rotating mirror. The SLM is composed of tiny liquid crystal cells that modify the propagating light, boosting its spatial resolution.

The SLM reproduces the refractive errors and pupil shape of myopic eyes, allowing the researchers to re-create myopic aberrations and to produce different aberrations depending on the angle of illumination. Using the SLM, the researchers programmed the aberrations as phase maps and induced programmed amounts of defocus to perform through-focus testing.

Tests helped the researchers determine the image quality within the proximity of a simulated retinal position, shedding light on how the special lens interacts with eye elongation signaled at the retina. “By combining the through-focus results with light-scattering measurements, we were able to accurately characterize several types of eyeglass lenses,” Arias-Gallego said. The researchers then compared measurements for each lens with their reported clinical efficacy for slowing myopia progression, he said.

The researchers quantified and compared the focusing and scattering properties of a single vision lens with two types of spectacle lenses for myopia progression management: defocus incorporated multiple segments (DIMS) and diffusion-optical technology (DOT). They calculated four optical metrics potentially related to myopia progress and quantified the scattered light from the peripheral lens zones. Scattering was quantified by implementing the optical integration method.

The characterization showed an increased contrast and sharpness of images through the DIMS lens at the peripheral retina when inducing myopic defocus, with respect to the single vision and DOT lenses. It further showed that contrast reduction by the DOT lens was dependent on the luminance at the pupil.

According to Arias-Gallego, the results both raised new questions and pointed to potential strategies that could increase the efficacy of future designs.

“Insights into the link between the optical properties of myopia progression management lenses and effectiveness in real-world scenarios will pave the way to more effective treatments,” Arias-Gallego said. “This could help millions of children and is fundamental in understanding the mechanisms by which these lenses work.”

The researchers are working to adapt the SLM instrument to include sources with varying wavelengths.

Bio Photonics Research Award

Visit: biophotonicsresearch.com
Nominate Now: https://biophotonicsresearch.com/award-nomination/?ecategory=Awards&rcategory=Awardee

#MeatAnalysis #FluorescenceTech #FoodQuality #FoodSafety #SpectroscopyInFood #MeatAuthentication #RapidDetection #FoodScience #MeatFreshness #MolecularDetection #FoodIndustryInnovation #NonDestructiveTesting #FoodMonitoring #SpectroscopyApplications #QualityControl #AdvancedSpectroscopy #MeatSpoilageDetection #FoodIntegrity #SmartFoodTesting #RealTimeAnalysis #FoodAuthenticity #FoodSafetyInnovation #SpectroscopyResearch #NextGenFoodSafety #InnovativeFoodScience,

DNA-Barcoded Fluorescence Imaging Illuminates Core Cell Components

Since many core components of cells — like DNA, RNA, proteins, and lipids — are just a few nanometers in size and substantially smaller than the resolution limit of traditional light microscopy, the exact composition and arrangement of these molecules and structures is thus often unknown. This results in a lack of mechanistic understanding of fundamental aspects of biology.

Drawing on recent improvements to superresolution imaging, including single-molecule localization microscopy, or SMLM, researchers from the Max Planck Institute of Biochemistry and Ludwig-Maximilians-Universität Munich have developed a technique that enhances the resolution of fluorescence microscopy down to the angstrom scale. The researchers’ technique enables the study of whole and intact cells over individual proteins — all the way down to the distance between two adjacent bases in DNA.

The researchers, from the group of Ralf Jungmann, called the technique resolution enhancement by sequential imaging, or RESI.

Current SMLM resolve structures on the order of 10 nm by temporally separating the structures’ individual fluorescence emission. As individual targets stochastically light up in an otherwise dark field of view, their location can be determined with subdiffraction precision. The SMLM technique of DNA points accumulation for imaging in nanoscale topography, or DNA-PAINT, uses the transient hybridization of dye-labeled DNA “imager” strands to their target-bound complements to achieve the light-up necessary to achieve superresolution.

To date, however, neither DNA-PAINT nor other superresolution methods have been able to resolve the smallest cellular structures.

RESI builds on DNA-PAINT and capitalizes on its ability to encode target identity via DNA sequences. By labeling adjacent targets, too close to each other to be resolved even by superresolution microscopy, with different DNA strands, an additional degree of differentiation — a barcode — is introduced into the sample. By sequentially imaging first one and then the other sequence to thereby capture the full target, the strands can now be unambiguously separated.

Critically, as they are imaged sequentially, the targets can be arbitrarily close to one other, which is a dynamic that existing techniques are unable to resolve. Further, RESI does not require specialized instrumentation and can be applied using any standard fluorescence microscope.

To demonstrate RESI’s leap in resolution compared to other methods, the researchers sought to resolve the separation between individual bases along a double helix of DNA, which is separated by less than 1 nm. They designed a DNA origami nanostructure that presented single-stranded DNA sequences that protrude from a double helix at one base pair distance.

The researchers then imaged these single strands sequentially and resolved a distance of 0.85 nm, or 8.5 Å between adjacent bases. They accomplished these measurements with a precision of 1 Å, or one ten-billionth of a meter.

According to the researchers, the technique is universal, with application beyond DNA nanostructures. In separate tests, Jungmann and his team investigated the molecular mode of action of rituximab, an anti-CD20 monoclonal antibody used for treatment of CD20-positive blood cancer. Investigating the effects of such drug molecules on molecular receptor patterns has been beyond the spatial resolution capabilities of traditional microscopy techniques. Understanding whether and how such patterns change in health and disease as well as upon treatment is important for mechanistic research and the design of targeted therapies.

The researchers used RESI to reveal the natural arrangement of CD20 receptors in untreated cells as dimers and uncovered how CD20 re-arranged to chains of dimers upon drug treatment.

Because RESI is performed in whole, intact cells, the technique closes the gap between purely structural techniques such as x-ray crystallography or cryogenic electron microscopy and traditional lower-resolution whole-cell imaging approaches.


Bio Photonics Research Award

Visit: biophotonicsresearch.com
Nominate Now: https://biophotonicsresearch.com/award-nomination/?ecategory=Awards&rcategory=Awardee

#MeatAnalysis #FluorescenceTech #FoodQuality #FoodSafety #SpectroscopyInFood #MeatAuthentication #RapidDetection #FoodScience #MeatFreshness #MolecularDetection #FoodIndustryInnovation #NonDestructiveTesting #FoodMonitoring #SpectroscopyApplications #QualityControl #AdvancedSpectroscopy #MeatSpoilageDetection #FoodIntegrity #SmartFoodTesting #RealTimeAnalysis #FoodAuthenticity #FoodSafetyInnovation #SpectroscopyResearch #NextGenFoodSafety #InnovativeFoodScience,

Agate Sensors Raises $6.6M for Everyday Spectroscopy Tech

Agate Sensors, a spinout of Aalto University developing smart sensors for material analysis, has raised €5.6 million (~$6.6 million) to commercialize a research breakthrough that shrinks spectroscopy from suitcase-sized lab equipment to a single pixel smaller than a grain of sand — integrated into a chip compact enough to sit on the tip of a finger.

The startup’s technology allows devices to analyze the spectral signatures of materials in real time, bringing high-precision material sensing out of the lab and into everyday devices, from smartphones and wearables to medical equipment and defense systems.

“We’ve taken a spectrometer once confined to specialized labs and made it small and affordable enough to live inside everyday devices,” said Tommi Leino, CEO of Agate Sensors. “One sensor can shift between functions entirely through software — from diagnosing a health condition to detecting, identifying, and classifying objects and materials — changing how we interact with the physical world.”

Manufacturing of initial chips is expected by year-end, enabling proof-of-concept demonstrators throughout 2026 and first commercial smart wearable products targeted for late 2027. According to the company, one of the earliest market ready applications lies in defense, as the sensor enables the distinction between real foliage and synthetic camouflage, or the identification of specific vehicle types via paint signatures.

The platform also has applications in machine vision, including multi-biomarker health monitoring in wearables, detection of counterfeit goods in supply chains, identifying environmental hazards in industry, and early intervention in smart agriculture and forestry, among other potential uses.

“This technology is the result of over a decade of research in semiconductor physics and nanotechnology at Aalto University,” said Andreas Liapis, CTO of Agate Sensors. “For the first time, we are able to bring laboratory-grade spectroscopy to an integrated form factor suitable for mass market use.”

The round includes €4 million in seed funding led by Voima Ventures and LIFTT, plus €1.6 million in grants from Business Finland.

Bio Photonics Research Award

Visit: biophotonicsresearch.com
Nominate Now: https://biophotonicsresearch.com/award-nomination/?ecategory=Awards&rcategory=Awardee

#MeatAnalysis #FluorescenceTech #FoodQuality #FoodSafety #SpectroscopyInFood #MeatAuthentication #RapidDetection #FoodScience #MeatFreshness #MolecularDetection #FoodIndustryInnovation #NonDestructiveTesting #FoodMonitoring #SpectroscopyApplications #QualityControl #AdvancedSpectroscopy #MeatSpoilageDetection #FoodIntegrity #SmartFoodTesting #RealTimeAnalysis #FoodAuthenticity #FoodSafetyInnovation #SpectroscopyResearch #NextGenFoodSafety #InnovativeFoodScience,

Two-Photon Microscopy Connects Hypoxia in Brain to Stalled Blood Flow

Using high-resolution imaging with two-photon phosphorescent lifetime microscopy (2PLM), researchers learned that even brief interruptions in blood flow to capillaries in the brain can cause rapid, localized drops in oxygen that probably extend into nearby brain tissue. These stalls in blood flow, in the smallest vessels in the brain, could play a role in brain diseases like stroke, Alzheimer’s disease, and traumatic brain injury, where such disruptions are common.

Using a two-photon phosphorescent probe, a team comprising researchers from Boston University and Massachusetts General Hospital monitored capillary flux and partial pressure of oxygen (pO2) in the mouse cortex. The researchers sought to quantify oxygen dynamics around capillary stalls as they occurred in vivo.

2PLM provided high-resolution measurement of the pO2 in the brain, enabling the researchers to investigate the distribution and consumption of oxygen. It offered the spatial and temporal resolution necessary to capture stalls using single point measurements.

The researchers excited phosphorescence at 950 nm with a pulse laser, and controlled excitation power with an electro-optic modulator. The excitation and emission light were split with a primary dichroic, and excess laser power was blocked by a filter in the detection path. Photons were detected by a photomultiplier tube after passing through a secondary dichroic and emission filter.

Imaging planes started at about 50 μm below the cortical surface and extended to an approximate depth of 250-300 μm. The researchers selected 10-20 points in each plane, based on capillaries with clear cross-sections parallel to the imaging plane.

At each point, the researchers performed 1000 cycles of 10 microsecond (10-μs) excitation, and 290 μs of collection and photon counting.

The researchers measured red blood cell passage and oxygen levels in more than 300 mice capillaries. Using 2PLM, they tracked the moments when red blood cells temporarily stopped moving through a blood vessel and monitored the resulting oxygen changes in real time.

To quantify the effect of stalling on oxygen, they monitored capillary oxygen, flux, and speed in 10 to 20 capillaries for about 10 minutes. They repeated these 10-minute recordings in several different regions of interest.

They found that every stall caused an immediate decline in oxygen within the capillary, which was likely to spread to surrounding tissue. About 40% of stalls dropped to levels considered hypoxic, and about 25% fell to levels where cells could not sustain normal energy production.

The severity of hypoxia differed depending on the animal’s state. Awake animals were far more vulnerable than mice under anesthesia, highlighting how dependent the brain is on uninterrupted microvascular flow under normal conditions.

The researchers also found that nearby capillaries sometimes showed small drops in oxygen when a neighboring vessel stopped flowing. This suggests that the impact of a stall may extend to the microvascular network surrounding the blocked vessel.

Because some capillaries tend to stall repeatedly, the tissue in their vicinity may experience repeated bouts of hypoxia over time, the team found. This could be one way that capillary dysfunction contributes to brain diseases where stalling is common. With the increased incidence of stalling that occurs with age or diseases such as Alzheimer’s and stroke, the potential for acute metabolic disruption is increased.

Future work could extend the measurements to deeper cortical layers and provide comparisons between healthy and diseased models. Flow and oxygen distributions are different across brain regions and could potentially be found to result in different dynamics around stalling events.

The brain depends on a constant supply of oxygen, and unlike other organs, it has minimal stores of energy. While it is known that blockages in larger vessels can have devastating consequences for the brain, less is understood about the effects of momentary stalls in the smallest vessels, the capillaries. These stalls have been observed more often in aging brains and in conditions such as Alzheimer’s disease, stroke, and traumatic brain injury.

The use of 2PLM to study when and where stalls in capillary flow occur, and result in pockets of low oxygen in the brain, could provide valuable information on a way that the conditions for various brain diseases may be exacerbated.

Bio Photonics Research Award

Visit: biophotonicsresearch.com
Nominate Now: https://biophotonicsresearch.com/award-nomination/?ecategory=Awards&rcategory=Awardee

#MeatAnalysis #FluorescenceTech #FoodQuality #FoodSafety #SpectroscopyInFood #MeatAuthentication #RapidDetection #FoodScience #MeatFreshness #MolecularDetection #FoodIndustryInnovation #NonDestructiveTesting #FoodMonitoring #SpectroscopyApplications #QualityControl #AdvancedSpectroscopy #MeatSpoilageDetection #FoodIntegrity #SmartFoodTesting #RealTimeAnalysis #FoodAuthenticity #FoodSafetyInnovation #SpectroscopyResearch #NextGenFoodSafety #InnovativeFoodScience,