Drug-free macromolecular therapies can induce cell apoptosis by clustering non-internalizing cell-surface receptors. These show enormous promise in tumor treatment, particularly in terms of non-specific toxicities when compared with low-molecular-weight drugs. However, most reported drug-free macromolecular therapies involve a ‘two-step’ administration manner and there is a paucity of in vivo research.
On December 23, 2021, the research team led by Prof. Du Yongzhong at the College of Pharmaceutical Sciences, Zhejiang University, published an article entitled “Spatiotemporally light controlled ‘drug-free’ macromolecules via upconversion-nanoparticle for precise tumor therapy” in the journal Nano Today.
Du’s team synthesized light-controlled ‘drug-free’ macromolecules consisting of up-conversion nanoparticles, aptamers, water-soluble polymers, and cinnamate (CA) groups. These macromolecules were first highly accumulated at tumor sites mediated by aptamers and precisely localized to receptors on the surface of tumor cell membranes. The up-conversion nanoparticles converted near-infrared light into ultra-violet light and induced the cross-linking of CA groups, thus resulting in the clustering of CD20 receptors and cell apoptosis. No apoptosis occurred in light-free sites. Therefore, tumors could be precisely treated in a safe and efficient manner. This strategy was confirmed by in situ and intravenous administration in tumor model animals.
“This near-infrared up-conversion controlled, in-situ synthesized drug-free macromolecular therapeutics expands the repertoire of macromolecular drugs and opens a new avenue for tumor therapy,” said Du.
Jun Wang et al, Spatiotemporally light controlled “drug-free” macromolecules via upconversion-nanoparticle for precise tumor therapy, Nano Today (2021). DOI: 10.1016/j.nantod.2021.101360
Light-controlled ‘drug-free’ macromolecules for precise tumor therapy (2022, January 7)
retrieved 9 January 2022
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Physics researchers at the University of Bath in the UK discover a new physical effect relating to the interactions between light and twisted materials—an effect that is likely to have implications for emerging new nanotechnologies in communications, nanorobotics and ultra-thin optical components.
In the 17th and 18th centuries, the Italian master craftsman Antonio Stradivari produced musical instruments of legendary quality, and most famous are his (so-called) Stradivarius violins. What makes the musical output of these musical instruments both beautiful and unique is their particular timbre, also known as tone color or tone quality. All instruments have a timbre—when a musical note (sound with frequency fs) is played, the instrument creates harmonics (frequencies that are an integer multiple of the initial frequency, i.e. 2fs, 3fs, 4fs, 5fs, 6fs, etc.).
Similarly, when light of a certain color (with frequency fc) shines on materials, these materials can produce harmonics (light frequencies 2fc, 3fc, 4fc, 5fc, 6fc, etc.). The harmonics of light reveal intricate material properties that find applications in medical imaging, communications and laser technology.
For instance, virtually every green laser pointer is in fact an infrared laser pointer whose light is invisible to human eyes. The green light that we see is actually the second harmonic (2fc) of the infrared laser pointer and it is produced by a special crystal inside the pointer.
In both musical instruments and shiny materials, some frequencies are ‘forbidden’ – that is, they cannot be heard or seen because the instrument or material actively cancels them. Because the clarinet has a straight, cylindrical shape, it supresses all of the even harmonics (2fs, 4fs, 6fs, etc.) and produces only odd harmonics (3fs, 5fs, 7fs, etc.). By contrast, a saxophone has a conical and curved shape which allows all harmonics and results in a richer, smoother sound. Somewhat similarly, when a specific type of light (circularly polarized) shines on metal nanoparticles dispersed in a liquid, the odd harmonics of light cannot propagate along the direction of light travel and the corresponding colors are forbidden.
Now, an international team of scientists led by researchers from the Department of Physics at the University of Bath have found a way to reveal the forbidden colors, amounting to the discovery of a new physical effect. To achieve this result, they ‘curved’ their experimental equipment.
Professor Ventsislav Valev, who led the research, said: “The idea that the twist of nanoparticles or molecules could be revealed through even harmonics of light was first formulated over 42 years ago, by a young Ph.D. student—David Andrews. David thought his theory was too elusive to ever be validated experimentally but, two years ago, we demonstrated this phenomenon. Now, we discovered that the twist of nanoparticles can be observed in the odd harmonics of light as well. It’s especially gratifying that the relevant theory was provided by none other than our co-author and nowadays well-established professor—David Andrews!
“To take a musical analogy, until now, scientists who study twisted molecules (DNA, amino acids, proteins, sugars, etc) and nanoparticles in water—the element of life—have illuminated them at a given frequency and have either observed that same frequency or its noise (inharmonic partial overtones). Our study opens up the study of the harmonic signatures of these twisted molecules. So, we can appreciate their ‘timbre’ for the first time.
“From a practical point of view, our results offer a straightforward, user-friendly experimental method to achieve an unprecedented understanding of the interactions between light and twisted materials. Such interactions are at the heart of emerging new nanotechnologies in communications, nanorobotics and ultra-thin optical components. For instance, the ‘twist’ of nanoparticles can determine the value of information bits (for left-handed or right-handed twist). It is also present in the propellers for nanorobots and can affect the direction of propagation for a laser beam. Moreover, our method is applicable in tiny volumes of illumination, suitable for the analysis of natural chemical products that are promising for new pharmaceuticals but where the available material is often scarce.
Ph.D. student Lukas Ohnoutek, also involved in the research, said: “We came very close to missing this discovery. Our initial equipment was not ‘tuned’ well and so we kept seeing nothing at the third-harmonic. I was starting to lose hope but we had a meeting, identified potential issues and investigated them systematically until we discovered the problem. It is wonderful to experience the scientific method at work, especially when it leads to a scientific discovery!”
Professor Andrews added: ”Professor Valev has led an international team to a real first in the applied photonics. When he invited my participation, it led me back to theory work from my doctoral studies. It has been amazing to see it come to fruition so many years later.”
The research is published in the journal Laser & Photonic Reviews.
Lukas Ohnoutek et al, Optical Activity in Third‐Harmonic Rayleigh Scattering: A New Route for Measuring Chirality, Laser & Photonics Reviews (2021). DOI: 10.1002/lpor.202100235
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Scientists have long theorized that supermassive black holes can wander through space—but catching them in the act has proven difficult.
Now, researchers at the Center for Astrophysics | Harvard & Smithsonian have identified the clearest case to date of a supermassive black hole in motion. Their results are published today in the Astrophysical Journal.
“We don’t expect the majority of supermassive black holes to be moving; they’re usually content to just sit around,” says Dominic Pesce, an astronomer at the Center for Astrophysics who led the study. “They’re just so heavy that it’s tough to get them going. Consider how much more difficult it is to kick a bowling ball into motion than it is to kick a soccer ball—realizing that in this case, the ‘bowling ball’ is several million times the mass of our Sun. That’s going to require a pretty mighty kick.”
Pesce and his collaborators have been working to observe this rare occurrence for the last five years by comparing the velocities of supermassive black holes and galaxies.
“We asked: Are the velocities of the black holes the same as the velocities of the galaxies they reside in?” he explains. “We expect them to have the same velocity. If they don’t, that implies the black hole has been disturbed.”
For their search, the team initially surveyed 10 distant galaxies and the supermassive black holes at their cores. They specifically studied black holes that contained water within their accretion disks—the spiral structures that spin inward towards the black hole.
As the water orbits around the black hole, it produces a laser-like beam of radio light known as a maser. When studied with a combined network of radio antennas using a technique known as very long baseline interferometry (VLBI), masers can help measure a black hole’s velocity very precisely, Pesce says.
The technique helped the team determine that nine of the 10 supermassive black holes were at rest—but one stood out and seemed to be in motion.
Located 230 million light-years away from Earth, the black hole sits at the center of a galaxy named J0437+2456. Its mass is about three million times that of our Sun.
Using follow-up observations with the Arecibo and Gemini Observatories, the team has now confirmed their initial findings. The supermassive black hole is moving with a speed of about 110,000 miles per hour inside the galaxy J0437+2456.
But what’s causing the motion is not known. The team suspects there are two possibilities.
“We may be observing the aftermath of two supermassive black holes merging,” says Jim Condon, a radio astronomer at the National Radio Astronomy Observatory who was involved in the study. “The result of such a merger can cause the newborn black hole to recoil, and we may be watching it in the act of recoiling or as it settles down again.”
But there’s another, perhaps even more exciting possibility: the black hole may be part of a binary system.
“Despite every expectation that they really ought to be out there in some abundance, scientists have had a hard time identifying clear examples of binary supermassive black holes,” Pesce says. “What we could be seeing in the galaxy J0437+2456 is one of the black holes in such a pair, with the other remaining hidden to our radio observations because of its lack of maser emission.”
Further observations, however, will ultimately be needed to pin down the true cause of this supermassive black hole’s unusual motion.
Dominic W. Pesce et al, A Restless Supermassive Black Hole in the Galaxy J0437+2456, The Astrophysical Journal (2021). DOI: 10.3847/1538-4357/abde3d
Astronomers detect a black hole on the move (2021, March 12)
retrieved 15 March 2021
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