Insight into how pharmaceutical solvents diffuse through a human nail

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Insight into how pharmaceutical solvents diffuse through a human nail (2015, June 19) retrieved 18 August 2019 from In a recent study, Wing Sin Chiu, Natalie A. Belsey, Natalie L. Garrett, Julian Moger, M. Begoña Delgado-Charro, and Richard H. Guy from the University of Bath and the University of Exeter developed a method to acquire real-time semi-quantitative data on solvent diffusion through a human nail using stimulated Raman scattering microscopy. Their research appears in the Proceedings of the National Academy of Sciences.Human skin, hair, and nails are made of a hard, fibrous protein called keratin. Keratin provides a protective barrier keeping unwanted compounds from easily entering the body. However, keratin’s ability to protect the body also makes it an obstacle for topical drug delivery. Up to now, it has only been possible to obtain time- and position-dependent data on the movement of chemicals through the outermost 20μm of the nail. In an effort to better understand the diffusion of key pharmaceutical solvents through a nail, Chiu et al. used stimulated Raman spectroscopy (SRS) to trace the movement of dimethylsulfoxide (DMSO), propylene glycol (PG), and water through several human nail samples.Stimulated Raman spectroscopy is an imaging technique that was first reported in 2008 for detecting small amounts of chemicals, such as pharmaceuticals or metabolites, within biological systems without having to use fluorescent labels. Since SRS is based on matching laser frequencies to chemical vibrational frequencies, it is able to neglect the environmental background, making it a good technique for non-invasive biomedical studies. Furthermore, SRS scan time is fast enough for real-time measurements. Explore further Journal information: Proceedings of the National Academy of Sciences For D2O, the Raman wavelengths were tuned to the O-D stretching band at 2,500 cm-1. Signals were taken as a function of time (every 2.7 minutes after t=10 minutes). After about thirty-five minutes, D2O had diffused ~100μm into the nail. The authors report that this is the first time that this kind of rapid, real-time transport of water through a nail has been visualized.Studies with deuterated DMSO and PG showed that they took much longer to diffuse through the nail. While water took less than an hour to penetrate 100μm, after a day, DMSO and PG only penetrated 40-50μm into the nail.Data analysis showed that the solvents deviate from classical diffusion behavior as the time of diffusion increases. Quantitative analysis was performed by accounting for several factors, including nail curvature, sample movement, and solvent depletion at the surface. Scans were normalized to keratin’s –CH2 frequency and analyses showed no significant solvent depletion at the nail surface. For each of the solvents, as diffusion time increased, the concentration profile deviated from classical behavior (Fick’s Second Law). Based on calculations using experimental results, this behavior is characteristic of a time- and concentration-dependent diffusion coefficient. Additionally, the rapid diffusion of water compared to the other two solvents indicates that there is a likely a strong molecular size dependence on diffusion across the nail. Finally, SEM imaging confirmed that the solvents loosen the nail structure and increase nail roughness, indicating that the nail is weakened when exposed to the solvents for a long period of time, which may lead to increased solvent diffusion over time. Additional studies of the nanostructure of the nail may provide further insight as to why solvent diffusion into a human nail deviates from classical behavior.This paper reports for the first time real-time solvent behavior as it is absorbed into a human nail. These results elucidate certain factors in drug solvent and nail bed uptake that will help in drug discovery and the development of topical medicines for nail disease. Play Orthogonal views of D2O penetration into human nail as a function of time. Credit: PNAS, doi: 10.1073/pnas.1503791112 Keratin has a characteristic –CH2 stretch at 2,855 cm-1 that Chiu et al. used to normalize SRS signals from the nail samples. Studies were conducted using deuterated solvents to easily distinguish the solvent vibrational bands from those of the nail. Concentration is linearly related to SRS signal allowing for a semi-quantitative measurement of solvent diffusion. This technique is “semi-quantitative” because of signal attenuation from light scattering as sample depth increases. In this case, signals from deeper within the nail would underestimate the amount of chemical present because the signal is slightly weakened with increasing depth. More information: “Molecular diffusion in the human nail measured by stimulated Raman scattering microscopy” PNAS, DOI: 10.1073/pnas.1503791112AbstractThe effective treatment of diseases of the nail remains an important unmet medical need, primarily because of poor drug delivery. To address this challenge, the diffusion, in real time, of topically applied chemicals into the human nail has been visualized and characterized using stimulated Raman scattering (SRS) microscopy. Deuterated water (D2O), propylene glycol (PG-d8), and dimethyl sulphoxide (DMSO-d6) were separately applied to the dorsal surface of human nail samples. SRS microscopy was used to image D2O, PG-d8/DMSO-d6, and the nail through the O-D, -CD2, and -CH2 bond stretching Raman signals, respectively. Signal intensities obtained were measured as functions of time and of depth into the nail. It was observed that the diffusion of D2O was more than an order of magnitude faster than that of PG-d8 and DMSO-d6. Normalization of the Raman signals, to correct in part for scattering and absorption, permitted semiquantitative analysis of the permeation profiles and strongly suggested that solvent diffusion diverged from classical behavior and that derived diffusivities may be concentration dependent. It appeared that the uptake of solvent progressively undermined the integrity of the nail. This previously unreported application of SRS has permitted, therefore, direct visualization and semiquantitation of solvent penetration into the human nail. The kinetics of uptake of the three chemicals studied demonstrated that each altered its own diffusion in the nail in an apparently concentration-dependent fashion. The scale of the unexpected behavior observed may prove beneficial in the design and optimization of drug formulations to treat recalcitrant nail disease. Compact structure of human nail revealed using red and green fluorescent dyes. Credit: Dr. Wing Sin Chiu. (—One of the biggest difficulties in treating nail disease is finding a topical drug that adequately penetrates through the nail. While some improvements in nail drug delivery have been made, they have been slow-going and still pose difficulties in treatment. A better understanding of drug delivery and solvent diffusion is needed. Parasite re-infection reduced by handwashing or nail clipping in Ethiopian children PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen © 2015 Phys.orglast_img read more

Best of Last Week – New way to detect dark matter a

first_img © 2015 Journal information: Scientific Reports Trio create artificial magnetic wormhole (—It was another good week for physics as Ian Shoemaker, until recently with the University of Southern Denmark, proposed a new theory, suggesting that if we want to detect dark matter, we might need a different approach—he believes that scientists should be looking for dark radiation signals that theoretically result from dark matter collisions. Also, another trio created an artificial magnetic wormhole—a three-layered sphere that makes it appears as if a magnetic field has suddenly disappeared and then reappeared somewhere else. In other news, a team of researchers in Rome and Geneva found a way to create tiny gears that increase light-to-work conversion efficiency by five orders of magnitude—by shining an LED light on tiny pinwheel-shaped gears floating on a liquid surface. Also, an international team of researchers came up with a way to fabricate hexagonal silicon, potentially leading to light-emitting semiconductors. They believe it could lead to new kinds of optical, electrical and superconducting materials. And another team at Cornell University reported on their efforts to explore the origins of energy in chemical reactions using experimental quantum chemistry.In unrelated news, a team of paleobotanists reported that they had identified what could be the mythical “first flower”—Montsechia vidalii, a plant that once grew abundantly in the Pyrenees and in the Iberian Range. Also, another team working at the Schoeneck-Kilianstaedten dig site in Germany reported that they had found evidence of a prehistoric massacre in Europe. In the interesting developments file, a team of researchers at the University of Texas Medical Branch at Galveston reported that they had developed a drug—a regenerative peptide—that protects against the deadly effects of nuclear radiation 24 hours after exposure. And there were reports, of course, of the Ashley Madison “cheater” files hitting the dark web—the hacker group made good on its promise to release data stolen from the site that specializes in providing a way for people to cheat on their partners.And finally, if you have ever found things getting weird when gazing into the eyes of a loved one for very long, you might have a lot of company, as a team of researchers has found that staring into someone’s eyes for a long time can cause hallucinations. Apparently, it happens to most people. Citation: Best of Last Week – New way to detect dark matter, a magnetic wormhole and staring found to cause hallucinations (2015, August 24) retrieved 18 August 2019 from Explore further (a) The field of a magnetic source (right) is appearing as an isolated magnetic monopole when passing through the magnetostatic wormhole; the whole spherical device is magnetically undetectable. (b) The wormhole is composed of (from left to right) an outer spherical ferromagnetic metasurface, a spherical superconducting layer, and an inner spirally wound ferromagnetic sheet. Credit: Scientific Reports 5, Article number: 12488 (2015) doi:10.1038/srep12488 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Researchers simulate information signaling between cells

first_img Citation: Researchers simulate information signaling between cells (2015, October 5) retrieved 18 August 2019 from This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. (—Many natural systems are described by dynamics of traveling wavefronts. Sharp traveling fronts are employed in countless phenomena, including fluid convection, chemical reactions, and cellular phenomena. Living systems use front propagation encoded in biochemical reactions to communicate and perform computations, but these dynamics are difficult to study in three dimensions (i.e., in vivo). Thus, to understand how propagating gene expression fronts work in complex living systems, it is important to study how they work in minimal systems. Artificial cells act like the real thing More information: “Propagating gene expression fronts in a one-dimensional coupled system of artificial cells.” Nature Physics (2015) DOI: 10.1038/nphys3469AbstractLiving systems employ front propagation and spatiotemporal patterns encoded in biochemical reactions for communication, self-organization and computation. Emulating such dynamics in minimal systems is important for understanding physical principles in living cells and in vitro. Here, we report a one-dimensional array of DNA compartments in a silicon chip as a coupled system of artificial cells, offering the means to implement reaction–diffusion dynamics by integrated genetic circuits and chip geometry. Using a bistable circuit we programmed a front of protein synthesis propagating in the array as a cascade of signal amplification and short-range diffusion. The front velocity is maximal at a saddle-node bifurcation from a bistable regime with travelling fronts to a monostable regime that is spatially homogeneous. Near the bifurcation the system exhibits large variability between compartments, providing a possible mechanism for population diversity. This demonstrates that on-chip integrated gene circuits are dynamical systems driving spatiotemporal patterns, cellular variability and symmetry breaking. Explore further © 2015 Journal information: Nature Physics A group of researchers in Israel and the United States report in Nature Physics the results of a study of a one-dimensional array of artificial cells in a silicon chip—in essence, a system of coupled cells in which the researchers could implement reaction-diffusion effects and study how they propagate among cells.Artificial cells?Artificial cells are engineered systems of various kinds that simulate a number of functions of biological cells. In this case, the array of cells consists of 15 compartments inside which the researchers patterned gene circuits. The compartments simulate the microencapsulation of the biological membranes of cells, separating the internal cellular mechanisms from other “cells” while allowing the exchange of small molecules.Carved into a silicon substrate, the compartments were fed by a main flow channel and interconnected by fork-shaped capillaries. Cell extract from Escherichia coli was fed continuously through the main channel. The researchers were interested in how biological multicellular systems use traveling wavefronts to communicate. Signals dissipate over short distances within a medium, so cells accomplish long-range transmission of information by consecutive local cell-to-cell interactions. In living systems, the transmission models are too complex to study, but this isolated array of artificial cells revealed interesting dynamics likely applicable to the study of actual multicellular systems.Though front propagation has been studied in the past, yielding results that have applications in science and industry, the authors note that this is the first time anyone has created a synthetic, spatially coupled cellular system capable of long-range cell-to-cell communication. The first compartment was patterned with a small amount of starter protein construct, and as the medium flowed through the channels, the researchers found that the DNA starter initiated diffusion of the activator to the neighboring compartment. This created an autocatalytic reaction in which the neighboring compartment created a new source of activator. The researchers characterized expression-diffusion dynamics by measuring the timescales between the diffusion of proteins along the capillaries, which occurred over minutes, and the gene expression dynamics in the compartments, which changed over hours. In essence, the researchers created a system of autocatalyzing protein synthesis in which the activator signal cascaded through the compartments, which amplified it and diffused it to neighboring compartments. The authors write, “The spatial organization of DNA circuits together with short interaction length, set by the array geometry, will allow integrating long-range signaling with local information processing reactions based on gene expression, in analogy to multicellular systems, electronic circuits, and neural networks.”last_img read more

Physics pair show that Ising model can be used as a universal

first_img Journal information: Science (—A pair of physicists has shown that it is possible to transform disparate spin models into different types of just one simple model. In their paper published in the journal Science, Gemma De las Cuevas, with the Max Planck Institute for Quantum Optics and Toby Cubitt, with University College London, offer a proof to show that any spin model can be converted to the relatively simple Ising model. Stephanie Wehner with QuTech, Delft University of Technology offers a Perspectives piece on the work done by the team in the same journal issue, outlining the proof and explaining how and why a universal spin model would be useful. © 2016 The benefit of having a universal model, Wehner explains, is that it offers an alternative way for scientists to run their models, particularly on a computer. If a 3D model is extremely complex, for example, or requires an untenable number of cycles to run, there is a chance it could be configured to run as an Ising model. But she notes that it could also be used as a means for melding the work being done by physicists and computer scientists, helping to further explain the workings of nature. Explore further Citation: Physics pair show that Ising model can be used as a universal spin model (2016, March 11) retrieved 18 August 2019 from Spin models were first developed as a means to help explain the properties of magnetic materials—the magnetism in each atom originates from the spin of an unpaired electron within it. The first was created by Wilhelm Lenz, who handed it off to Ernest Ising, who used it to show that spins should undergo phase transitions below a certain temperature. Since that time, spin models have been developed for a wide variety of applications, perhaps most notably in particle physics. Now, in this new effort, De las Cuevas and Cutitt show that it is possible to transform any of these other newer models into the 2D Ising model, including 3D models.Their proof has two main parts, the first involved showing that any Ising model is equivalent to an instance of a satisfiability problem and showing a way to match such problems to an Ising model. The second part involved showing how any spin model could be converted to a satisfiability problem and then translated to an Ising model.last_img read more

Sediments in Gulf of Naples reveal impact on Roman water distribution after

center_img Journal information: Proceedings of the National Academy of Sciences Citation: Sediments in Gulf of Naples reveal impact on Roman water distribution after Vesuvius eruption (2016, May 17) retrieved 18 August 2019 from Explore further (—A team of researchers with members from France, the U.S., the U.K. and Italy has found evidence of disruptions to the water delivery system in the area around Naples after the eruption of Mount Vesuvius in AD 79. In their paper published in Proceedings of the National Academy of Sciences, the team describes their testing of sediment cores taken from the harbor at Naples, what they found and what their study has revealed about the history of the area.last_img read more

Images made of relativistic electrons trapped in graphene quantum dots

first_img Journal information: Nature Physics (—A team of researchers with the University of California, MIT, Lawrence Berkeley National Laboratory and the National Institute for Materials Science in Japan has created images of relativistic electrons trapped in graphene quantum dots. In their paper published in the journal Nature Physics the team describes how they achieved this feat and where they plan to take their work in the future. Researchers find electron chirality in graphene impacts current flow As the many unique properties of graphene continue to unfold, scientists seek new ways to harness and eventually make use of them. One such use might be to control electrons to allow their use in nano-scaled devices, which could also inadvertently lead to a deeper understanding of Dirac fermions. In this new effort, the researchers have made progress in that area by devising a means for capturing and holding electrons and for creating images of the result.Obtaining images of electron waveforms has thus far been particularly difficult—virtually all existing methods have resulted in too many defects. To get around such problems, the researchers took another approach to capturing the electrons. They first created circular p-n junctions by sending voltage through the tip of a scanning tunneling microscope down to a graphene sample below. At the same time, they also applied voltage to a slab of silicon underneath the piece of graphene, which was kept separated by a layer of silicon-oxide and a flake of boron nitride. Doing so caused defects in the boron nitride to ionize, resulting in charges migrating to the graphene.To create images of those charges, the researchers placed a scanning tunneling microscope tip just above the surface of the quantum dot, which allowed for measuring the tunneling current—moving the tip to different locations allowed for taking multiple measurements which when taken together allowed for creating an image.The new method, the team suggests, could be used as the basis for developing systems that are more complicated, such as those with multiple quantum dots. They next plan to investigate using their technique with bilayer graphene samples, which hold far more Dirac charge carriers to see if they reflect when they impinge on the p-n junction barrier in expected ways. The STM tip spatially probes Dirac fermion wavefunctions in the presence of the p–n junction. Credit: (c) Nature Physics (2016). DOI: 10.1038/nphys3805 More information: Juwon Lee et al. Imaging electrostatically confined Dirac fermions in graphene quantum dots, Nature Physics (2016). DOI: 10.1038/nphys3805AbstractElectrostatic confinement of charge carriers in graphene is governed by Klein tunnelling, a relativistic quantum process in which particle–hole transmutation leads to unusual anisotropic transmission at p–n junction boundaries. Reflection and transmission at these boundaries affect the quantum interference of electronic waves, enabling the formation of novel quasi-bound states. Here we report the use of scanning tunnelling microscopy to map the electronic structure of Dirac fermions confined in quantum dots defined by circular graphene p–n junctions. The quantum dots were fabricated using a technique involving local manipulation of defect charge within the insulating substrate beneath a graphene monolayer. Inside such graphene quantum dots we observe resonances due to quasi-bound states and directly visualize the quantum interference patterns arising from these states. Outside the quantum dots Dirac fermions exhibit Friedel oscillation-like behaviour. Bolstered by a theoretical model describing relativistic particles in a harmonic oscillator potential, our findings yield insights into the spatial behaviour of electrostatically confined Dirac fermions.center_img © 2016 Explore further Citation: Images made of relativistic electrons trapped in graphene quantum dots (2016, July 15) retrieved 18 August 2019 from This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

An ordinary fare

first_imgBetween 1 to 2 pm only on Mondays madam, says the voice on the other end when I call up to confirm if walk-in is an option for outsiders in Rajasthan Bhawan’s canteen. Sensing my interest in the Rajasthani cuisine, he immediately adds that anybody could walk-in on any day of the week but the Rajasthani thali or platter is a once-a-week affair at the canteen. So, I waited for almost a week for that preordained lunch hour to gorge on the delicious Rajasthani platter here in the Capital. And when the day approached, monsoon, with all its splendour, had finally arrived in the Capital, casting a perfect setting for my lunch. I started out early to make it on time; well, I had only a bracketed hour-long time for the meal.  Also Read – ‘Playing Jojo was emotionally exhausting’Walking inside the foyer of Rajasthan Bhawan, I glided down a step of stairs to find the canteen in a corner. A sizeable window in the canteen peeps into a hall with tables dressed in white linen and plastic covers set around wooden seats. Amongst the first few to arrive, I was delighted to make it on time. The attendant however informed me that I was early for lunch and food will be served by 1 pm. By and by, the hall started filling up with seemingly in-house guests and bureaucrats and it was half past 1 by the time the thalis made their first appearance. Indian Standard Time dutifully observed! Turning into a one man army, one attendant whizzed around the hall distributing thalis. By the time my moderately warm thali arrived, it was well past 1:30 pm.  Also Read – Leslie doing new comedy special with NetflixI scanned the thali and noticed the special daal-baati-churma alongside a dish of mix vegetable, gatta curry (gram flour dumplings in curry), rice and chapatis. Baati was bang on, crunchy and smoky in texture and the finely coarse churmawas mildly sweet. But what remained elusive was the conspicuous absence of ghee in the course. What stood out for me was the simple and tangy gatta curry.I have never imagined eating daal-baati-churma without ghee; it seems dry and takes down the entire experience by several notches. Well, the food came in late, the ghee never arrived, and there was nothing in the tapestry or up on the walls to hook onto.  Give this one a miss, without batting an eyelid.Meal for two : Rs 220 onwardslast_img read more

Sufi music can never be commercialised

first_imgHow did music come calling to you?Music is not a mere profession to us, it is a legacy we are carrying which has been blessed to us by our ancestors.Have qawali and sufi music got their due in the music circuit?Qawali and sufi music has its own place in the music circuit. Sufi and qawali are not commercial rather they are integral to our tradition.Are you open to Bollywood offers after Rockstar?After the success of music of Rockstar we got a brilliant response from the audience and critics. Yes we are open to work on more Bollywood assignments, infact we are working on few things, will soon announce when something positive develops. Also Read – ‘Playing Jojo was emotionally exhausting’What does music mean to you?Music to us is our passion and obligation to do justice everytime we perform. As our ancestors has earned respect on the basis of this only, so its our responsibility to take it further.Do you follow any other Indian or foreign musicians. If yes, what do you like in them?We do not to name of any artist but we really follow sufi songs, shayari and chants of Amir Khusro.Have you thought about coming out with your own label or album? Also Read – Leslie doing new comedy special with NetflixCurrently we are planning something, but is it has a long way to go.Would you ever like to experiment with your genre of music or try fusion?It’s great to be a versatile and we respect all the genres of music be it fusion or some other. But right now we are not planning to experiment with our genre.How has the journey been for all these years?Our journey, right from the start, was tough. Firstly to maintain the name of our ancestors was a big challenge for us. The love and admiration we got from the audience just cannot be expressed in words.How does the audience react to your music on international shores. Do they accept it well?It really makes us proud that people in other countries love sufi music and its amazing to see their attendance at the concerts. Sometimes it happens that they don’t understand the music and lyrics completely, but is really great to see their admiration towards us.last_img read more

Mind over matter

first_imgThis may be his debut solo art show but 24-year-old Pallav Chander is not new to the world of arts. He has regaled many an audience with his portrayal of a woman in the play Mahim Junction, has created larger-than-life sets for his other theatrical productions and been a witness to India’s contemporary art scene as the only child to Kanchan Chander, a well-known artist of our times.It’s no wonder then, that even for his debut art show, titled Decoding A Dyslexic Mind that will be held at Visual Arts Gallery, India Habitat Centre, New Delhi from March 1 till March 6, 2014, 10 a.m. to 6 p.m., Pallav shows a remarkable confidence in the autobiographical 35-odd works which include oils on canvas, acrylic on canvas and paperworks. Transcending mediums and genres – he has created textural, semi-abstract figurative works and abstracts too.  Chander’s imagination is inspired by mainly one theme – his own life. Also Read – ‘Playing Jojo was emotionally exhausting’That he is dyslexic and a large part of his work features hands is Chander’s may not be ‘a direct message to not consider dyslexics as abnormal’, but Pallav does concede that he was the brunt of many taunts as a school-going child and Aamir Khan’s Taare Zameen Par did ‘help me a lot’. As art curator Roobina Karode writes in the catalogue essay: ‘Decoding a dyslexic mind is about a particular mind, about Pallav Chander, a young artist who, one fine day snapped out of memories of his uncomfortable school days and grew up to do what he enjoyed the most- make art. While still in school, Pallav had experienced a certain lack of speed in comprehending and writing and these grasping difficulties instilled a certain anxiety towards social interaction and team work in the classroom. As he came to be aware of his disability, but had not yet learnt to come to terms with being dyslexic, he shied away from people, often due to peer pressure and the fear of being judged. With his mother’s constant effort and encouragement Chander was first introduced to performing arts and theatre workshops in the city, and this brought a gradual but dramatic change in his persona, as he had to be on stage and give his role the required emotion in front of an audience. His appetite for the arts was reinforced by his experiences doing theatre.’ Also Read – Leslie doing new comedy special with Netflix’Of course it was tough as a dyslexic child, and all these works are almost autobiographical. Not only do they reflect my present state of mind but also my growing up years after my parents separated.  Hands came into my work from my experiences in the UK. Each and every hand for me is like a memory, a moment from my life which I would want to remember,’ says Chander.WHERE: Visual Arts Gallery, IHC (till 6 March); Passage Art, Khan Market (7 March to 31 March)last_img read more