IIT Madras team produces white light using pomegranate, turmeric extract

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Dr. Vikram Singh produced white light by irradiating the pomegranate extract and carbon nanoparticles made from pomegranate extract with UV light.

Dr. Vikram Singh, former research scholar in the Department of Chemistry, IIT Madras won the BIRAC Gandhian Young Technological Innovation (GYTI) Award 2017 for his work on producing white light emission using natural extracts.

Dr. Singh and Prof. Ashok Mishra from the Department of Chemistry, IIT Madras used a mixture of two natural extracts — red pomegranate and turmeric — to produce white light emission. The researchers used a simple and environment-friendly procedure to extract dyes from pomegranate and turmeric.

While polyphenols and anthocyanins present in red pomegranate emit at blue and orange-red regions of the wavelength respectively, curcumin from turmeric emits at the green region of the wavelength. White light emission is produced when red, blue and green mix together. This is probably the first time white light emission has been generated using low-cost, edible natural dyes. The results were published in the journal Scientific Reports.

“We had to mix the two extracts in a particular ratio to get white light,” says Dr. Singh, the first author of the paper; he is currently at Lucknow’s CSIR-Central Drug Research Institute (CDRI). By changing the concentration of the two extracts the researchers were able to get different colour temperatures (tunability).

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White light produced by irradiating UV at 380 nm.

“When we mix the two extracts and irradiate it with UV radiation at 380 nm, we observed energy transfer (FRET mechanism) taking place from polyphenols to curcumin to anthocyanins, which helps to get perfect white light emission,” says Dr. Singh. For FRET mechanism to take place there must be spectral overlap between a donor and an acceptor.

In this case, there is a perfect overlap of emission of polyphenols with absorption by curcumin so the energy from polyphenols is transferred to curcumin. Since there is also a perfect overlap of emission of curcumin with absorption by anthocyanin, the energy of curcumin is transferred to anthocyanin.

As a result of this energy transfer from one dye to the other, when the extract is irradiated with UV light at 380 nm (blue region of the wavelength), the polyphenols emit in the blue region of the wavelength and transfers its energy to curcumin. The excited curcumin emits in the green region of the wavelength and transfers its energy to anthocyanin, which emits light in the red region of the wavelength.

“Because of the energy transfer, even if you excite in the blue wavelength we were able to get appropriate intensity distribution across the visual wavelength,” says Prof. Mishra, who is the corresponding author of the paper.

White light sans turmeric  

Taking the work further, the duo produced carbon nanoparticles using pomegranate and to their surprise it was producing fairly green emission. So instead of using turmeric to get green wavelength, the researchers used carbon nanoparticles made from pomegranate extract. “We could get white emission, though it is not as white as when we used turmeric. It’s slightly bluish but well within the white zone,” says Prof. Mishra. “It is attractive to use a single source to create white light emission.”

The principle by which the pomegranate extract and carbon nanoparticles made from the extract is the same as in the case when pomegranate and turmeric extracts were used. The results were published in the Journal of Materials Chemistry C.

Though this natural mixture of dye can be used in a wide variety of applications such as tunable laser, LEDs, white light display, much work needs to be done in terms of photostability and chemical stability before it becomes ready for translation. Biosystems have an inherent tendency to breakdown and so this has to be addressed.

Published in The Hindu on May 6, 2017

IIT Madras’ baby steps to develop data glove for the speech-disabled

Data glove-OptimizedA data glove, which measures the individual joint angles of all the five fingers to understand the activity daily living, developed by Nayan Bhatt, Research Scholar from the Department of Applied Mechanics, IIT Madras recently won the Budding Innovators Award given by the Delhi-based National Research Development Corporation (NRDC). He has been working on developing models for studying finger kinematics for the last three years.

The data glove has 15 sensors (plus an additional reference sensor) that help in gathering information about kinematic or hand motion. The sensors are placed on the segments of a finger; each finger has three segments and the junction between two segments forms a joint. Each sensor is connected to a microcontroller board using a flexible wire to collect data.

“The sensors measure the joint angles through the change in orientation information. We are interested in gathering information about motion of the fingers excluding the wrist,” says Mr. Bhatt. “In the case of people with Parkinson’s disease, the data glove will provide information about hand kinematics and help clinicians assess the severity of disease. It will compliment the traditionally used Universal Parkinson’s Disease Rating Scale.” It may find application in animation and other industries.

Unlike in the case of the conventional data glove, the sensors are placed directly on each segment of the finger to avoid any deformation. “We placed the sensors directly on the segments of fingers as the use of cloth, like in a traditional data glove, can hinder natural movements and also cause slippage or deformation,” he says.

Efforts are now on to reduce the number of sensors used. “We will first use all the 15 sensors to perform some training postures which will then be used for developing an algorithm that will reduce the number of sensors used. With the machine learning algorithm developed by Bhatt we can use as few as eight sensors. We want to reduce it to six,” says Dr. Varadhan S.K.M. from the Biomedical Engineering Division of the Department of Applied Mechanics, IIT Madras.

“We are using the prototype to develop products for speech-related disability,” says Dr. Varadhan. “By using specific movements of a finger for specific words the data glove can help speech-disabled people to communicate. We can use a speech synthesiser and speaker to generate sound.” Work has to be done to first map specific words to specific movements of the finger.

A finger can move in different directions. So the total number of joint angles is about 21. Sensors have been used to sense all the 21 angles. “Ten predicted angles have large errors of more than 2 degree and the remaining angles have less than 2 degree error. The average is 5 degrees. In a few months with advance algorithms we might be able to reduce the average prediction error to 2-3 degrees,” says Dr. Varadhan.

Published in The Hindu on April 26, 2017

IIT Madras’ first step to develop cheaper cancer diagnostic alternative

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Dr. Swati Choudhary (left) and Prof. Rama Verma tested the fusion protein diagnostic on leukaemia and colorectal cancer samples.

A team of researchers from the Indian Institute of Technology (IIT) Madras has developed a cheaper yet reliable alternative for diagnosing leukaemia and colorectal cancer. Like monoclonal antibodies which are currently used for cancer diagnostics, the fusion protein developed by the researchers has high specificity and sensitivity. The results were recently published in the journal Molecular Diagnosis & Therapy.

The researchers designed recombinant fusions of a ligand (stem cell factor) to a protein tag (SNAP-tag). The ligand binds to a particular receptor (c-kit) that is present in more than normal numbers (overexpressed) on some cancer cells.

To quantitatively determine the amount of ligand that is bound to the receptors, the researchers used a commercially available fluorescent material (O6-Benzylguanine) that the SNAP-tag binds to. The bound protein with the fluorescent derivative can be detected using a fluorescent microscope or flow cytometry.

“We report the first evidence that SNAP-tag could be used for ex vivo [outside the body] detection of enriched biological markers using SCF/c-kit as the target receptor system. The c-kit receptor is a pathological and diagnostic marker for a variety of cancers,” Dr. Swati Choudhary from the Department of Biotechnology, IIT Madras and the first author of the paper says in an email. “It is a proof-of-concept study.”

Using c-kit positive and negative cell lines, the researchers first tested the capacity of the protein tag to bind specifically to the c-kit receptors. “The specificity was comparable to the currently used monoclonal antibodies,” she says. “We then carried out a pilot study to test whether these proteins could be used for diagnostic purposes through ex vivo immunophenotyping of the c-kit receptor. We tested it on 16 peripheral blood samples from leukaemia patients and four colorectal biopsy specimens.”

“The sensitivity is as good as commercially available monoclonal antibodies. If sensitivity and specificity are high in large-scale studies, we could in future replace monoclonal antibody with SNAP-tag fusions to select ligands for diagnostic applications. It will also be much cheaper,” says Prof. Rama S. Verma from the Department of Biotechnology, IIT Madras, and one of the corresponding authors of the paper.

“In the long term, these probes could potentially be used for diagnosing and staging of cancer and in the follow-up management of the disease,” Dr. Choudhary says. According to Prof. Verma, it would even be possible to find out early stages of cancer as the technique has high sensitivity.

Since c-kit receptor is overexpressed in other cancers such as gastrointestinal stromal tumours, small cell lung cancer, ovarian cancer, breast cancer and melanoma, the SNAP-labelled protein could theoretically be used for diagnosing these cancers as well. Further studies are needed to confirm this.

“By replacing the stem cell factor with different ligands that targets other cancer cells, the technique can potentially be used for identifying other cancers as well,” Dr. Choudhary says.

As a DAAD fellow, Dr. Choudhary carried out a part of the study at Fraunhofer Institute of Molecular Biology, Aachen, Germany.

Published in The Hindu on February 19, 2017

IIT Madras researchers study the role of mushroom spores in atmospheric bioaerosols

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Prof. Verma, Hema and Prof. Gunthe studied the contribution of mushroom spores to aerosols.

Researchers from the Indian Institute of Technology (IIT) Madras have for the first time, over the Indian region, demonstrated the potential role of mushroom spores in atmospheric bioaerosols. While others have studied the diversity and distribution of mushroom and the presence of mushroom spores in atmospheric aerosol separately, the IIT team has proven the role of terrestrially occurring mushrooms as a source of biological aerosol particles in the atmosphere. The results were published recently in the journal PLOS ONE.

The study was undertaken on IIT Madras campus, which is spread over 678 acres and has very rich vegetation. It is considered an ‘ecological island’ representative of tropical dry evergreen biome.

Biodiversity of fungal species in the study site was studied using DNA analysis. To identify the type and diversity of atmospheric fungal spores, DNA analysis of particulate matter was carried out subsequently. The DNA analysis of 165 mushrooms revealed that there are 113 different species of mushrooms belonging to 54 genera and 23 families.

“Source characterization of airborne fungal spores has been done for the first time in India — we studied the mushrooms and spores released by the mushrooms oand present in air,” says Prof. Sachin S. Gunthe from the Department of Civil Engineering, IIT Madras and the corresponding author of the paper.

“Mushrooms grow during monsoon and when the temperature and relative humidity are favourable spores are released into the air,” says Prof. R.S. Verma from the Department of Biotechnology, IIT Madras and one of the authors of the paper.

“There was 17% match between mushroom species found on land and spores in the air,” says Hema Priyamvada, a doctoral student from the Department of Civil Engineering, IIT Madras and the first author of the paper. Spores collected from the mushroom and from the air were studied to understand how the spores look morphologically — size, shape and surface features.

“Morphological characterization of fungal spores will be useful for identification of spores in the atmosphere. Since fungal spores account for huge fraction of bioaerosols, the SEM images will be helpful in quick and efficient identification,” says Priyamvada.

The researchers have also quantitatively estimated the contribution of mushroom spores to atmospheric aerosol by modelling the dispersion of spores from the mushroom. “We found that of the certain number of spores (540 spores per sq. cm) released per second from a mushroom, 6% reached a distance of 100 metres for one second of release. In ambient conditions, the release can happen for a longer time — up to an hour — so the contribution of spores to the atmospheric aerosols will be huge,” she says. “Once released from mushrooms, spores can remain suspended in air for a long time and travel great distances.”

“We tried to show mushrooms growing in similar kind of ecosystem as IIT Madras are releasing spores into air. It means, to an extent, you can extrapolate these findings to other tropical dry evergreen biome in India,” says Prof. Gunthe.

Besides causing allergy in humans, spores can also damage plants and animal health. It can also have an impact on regional climate. By acting as ice nuclei, the fungal spores can accelerate vapour condensing around spores and forming water droplets. “Presence of specific type of bioaerosols can even advance the precipitation processes especially in convective clouds,” says Prof. Gunthe.

Published in The Hindu on February 12, 2017

IIT Madras develops a novel electrode material for lithium batteries

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(From left) Prof. Sundara Ramaprabhu, Ananya Gangadharan and Sripada Raghu from the Department of Physics, IIT Madras have combined two storage mechanisms in one battery to achieve high capacity retention.

A team of researchers at the Indian Institute of Technology (IIT) Madras has been able to enhance the capacity retention of anode material in lithium ion batteries four-fold compared with commercially available ones.

The team was able to develop a novel composite which can deliver specific capacity retention of 1,120 mAh/g after 10,000 cycles, and work at high current density (ability to draw more current from a cell within a short time) with long cycle life by combining two types of lithium ion storage mechanisms. The results were published in the Journal of Materials Chemistry A.

Compared with graphite, carbon nanotube (CNT) has several advantages as an anode material. However, the efficiency (or irreversible capacity) of carbon nanotube anode is an issue. Also, the lithium ions that get inserted into the carbon nanotube during charging do not fully come out during discharge. So not all lithium ions inserted into carbon nanotube comes out to contribute to the useful capacity.

“We overcame this by using carbon nanotubes with a few layers unzipped, which can be called as partially exfoliated carbon nanotubes,” says Sripada Raghu from the Department of Physics, IIT Madras and one of the authors of the paper. The unzipping does not affect the core of the CNT structure, which renders very good electrical conductivity, while the partially exfoliated outer layers have very good ability to store lithium ions. “The outer layers of partially exfoliated carbon nanotubes are quite similar to a few-layered graphene,” Mr. Raghu says.

To enhance the capacity even further, the researchers incorporated sulphur in the exfoliated layers. The theoretical capacity of sulphur is very high (1,675 mAh/g). So the team wanted to take advantage of this property of sulphur.

Besides getting inserted into the layers of exfoliated carbon nanotube, the lithium ions interact with sulphur in a chain of reactions leading to the formation of lithium polysulphides. Higher-order polysulphides are initially formed and later the stable lower-order polysulphides are formed. “The lower-order polysulphides are desirable,” says Ananya Gangadharan from the Department of Physics, IIT Madras and the first author of the paper.

“We have clubbed the two storage mechanisms — lithium ion insertion reaction from the lithium ion battery and sulphur redox reaction from the lithium sulphur battery — in one battery. That’s why we are able to achieve high capacity retention even after 10,000 cycles at high current density,” says Ms. Gangadharan.

“We have already patented our anode material. We are now trying to combine the anode with suitable cathodes and test the enhancement in efficiency and capacity retention so we can replace the commercial anodes with ours,” says Prof. Sundara Ramaprabhu from the Department of Physics, IIT Madras and the corresponding author of the paper. “Work is currently on to further enhance the capacity and use the material as an electrode in both lithium ion and lithium sulphur batteries.”

Published in The Hindu on January 7, 2017

IIT Madras researchers prove the superiority of arsenic water filter which got $18 million funding

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AVULA ANIK KUMAR AND OTHERS FROM IIT MADRAS SHOWED THAT THE AMOUNT OF ARSENIC LEACHED FROM A SATURATED FILTER WAS FAR LESS THAN THE BACKGROUND CONCENTRATION.

An exhaustive research carried out by a team of researchers led by Prof. T. Pradeep from the Department of Chemistry at the Indian Institute of Technology (IIT) Madras, spread over four years has put to rest the scepticism about the merits of the arsenic water filter developed by them. The water filter has been in operation for three and half years in about 900 sites in India serving close to 400,000 people.

Arsenic in drinking water is the largest natural mass poisoning in the history of humanity, affecting 13 crore people globally. The problem of arsenic in the environment, known for over 102 years, has not been solved satisfactorily, due to the non-availability of appropriate and affordable materials. Arsenic is a slow poison causing numerous health effects, including cancer and genetic anomalies.

The IIT technology makes use of confined metastable 2-line iron oxyhydroxides and its large adsorption capacity to remove arsenic in two different dissolved forms (arsenate and arsenite).  The filter was able to reduce the arsenic concentration in the water from 200 ppb to well below the WHO limit of 10 ppb. The results were published recently in the journal Advanced Materials.

“The arsenic removal capacity of the material filter was found to be 1.4 to 7.6 times better than all the other available materials,” says Prof. Pradeep. “The superior arsenic uptake capacity is due to its inherent structure. Nanostructured iron oxyhydroxide makes many sites available for arsenic uptake. The ions of arsenic adsorb on the nanoparticles at specific atomic positions. No nanoparticles are released into the purified water due to the biopolymer cages in which they are contained.”

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The team has now tested a three-stage water filter for domestic use. The output water contained arsenic and iron below the WHO limit.

The team mimicked the average arsenic concentration seen in West Bengal — 200 ppb of arsenic — for carrying out several laboratory studies. Though studies were carried out at a pH of 7.8, the team found the adsorption capacity of the filter was not compromised in the pH range 4 to 10. “The pH of drinking water is in the range of 6.5 to 8.5.  But we tested the filter in a wide range of pH so it can be used for other purposes as well,” says Prof. Pradeep.

“A filter composed of 60 grams of the material can be used safely for removing arsenic (200 ppb) from 1150 litres of water and till such time the concentration of arsenic in the filtered water does not cross the WHO limit of 10 ppb,” he says. Once the filter has reached its saturation limit it has to be reactivated or recharged with new material.

Reactivation is done by soaking the material in sodium sulphate solution for an hour at room temperature. It is further incubated for about four hours after reducing the pH to 4. “Using this reactivation protocol we reused the same filter seven times,” he says.

Studies were carried out to test if the adsorbed arsenic leached from the filter. The team found that the amount of arsenic that got leached was 1 ppb in the case of arsenite and 2 ppb for arsenate. “Soil in the affected regions also contains arsenic, typically around 12 ppb of arsenic, which is the background concentration. The amount of arsenic leached from the saturated filter was far less than the background concentration,” Prof. Pradeep says. Leaching of arsenic from disposed filters was one of the biggest criticisms by a few researchers who had worked on arsenic filters. Arsenic, being an element, cannot be degraded further to simpler species.

Since the arsenic filter developed by the team has so far been in use at a community level, studies were carried out to test its performance as a domestic water filter. A domestic three-stage filter was developed to remove particulate matter, iron and arsenic. Input water containing 200 ppb of arsenic and 4 ppm of Fe(III) was passed through the filter for a total volume of 6,000 litres (translating to 15 litres of water per day for one year). “The output was below the WHO limit for both arsenic and iron throughout the experiment,” he says.

“For a family of five, arsenic-free drinking water can be produced at $2 per year,” he says.

In the course of the development of this technology, he and his former students incubated a company, InnoNano Research Pvt. Ltd. at IIT Madras. In July this year, the company received venture funding to the tune of $18 million.

“With this research, a home grown technology appears to be all set for global deployment. Knowledge is no more a limiting factor for solving the arsenic menace,” he said.

Related Stories:

With $18 million venture funding, IIT Madras Prof breaks the glass ceiling

IIT Madras: Affordable water purification using silver nanoparticles

Published in The Hindu on December 18, 2016

IIT Madras researchers with a Midas touch, on a nanoscale

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(From left) Prof. T. Pradeep, K.R. Krishnadas, Atanu Ghosh, Ganapati Natarajan (standing) and Ananya Baksi (not in the photo) transformed nanoparticles of silver to gold.

In a breakthrough, a team of researchers from the Indian Institute of Technology (IIT) Madras has successfully transformed nanoscale pieces of silver to gold and gold to silver by replacing their atoms one at a time. The shape and structure of these materials before and after transformation are identical, although they are completely different chemically. The result were published today (November 10) in the journal Nature Communications.

“This is like transforming a silver Nataraja sitting on your table to a gold equivalent, by atom-by-atom changes. Although this is possible only in the nanoscale, that too with limited systems today, there is a hope that such changes can occur in the macroscopic world in future” says Prof. T. Pradeep, from the Department of Chemistry, IIT Madras and the corresponding author of the paper.

When nanoparticles of gold and silver, which have different mass but identical atomic arrangements, are mixed in solution at room temperature an atom by atom replacement takes place. Within a few minutes the silver nanoparticle becomes a gold nanoparticle and the gold nanoparticle becomes a silver nanoparticle. Generally, nanoscale materials are more reactive as they have higher energy compared with bulk matter.

A structure of gold just becomes another identical structure of silver or vice versa. No principle of science is violated.“If changing objects atom by atom is easily possible, tomorrow we can produce novel alloys that might have very different, unknown properties,” says Prof. Pradeep.

“This is not the medieval magic of converting everything to gold. Here, gold does not become silver. Instead, a structure of gold just becomes another identical structure of silver or vice versa. Number of atoms of gold and silver are the same. No principle of science is violated,” he says. “We are only creating conditions such that one structure transforms to another.”

During such transformations, alloys of different compositions of gold (Au) and silver (Ag) are formed. For instance, when silver nanoparticle composed of 25 atoms react with a gold nanoparticle composed of 25 atoms, one atom from the silver nanoparticle is replaced with one atom of gold particle, to form an AuAg24 alloy. The silver atom removed from the silver nanoparticle in turn takes the place of the gold atom in the gold nanoparticle to form an AgAu24 alloy.

As the reaction proceeds, the number of atoms of one metal in an alloy keeps increasing while the other metal keeps decreasing. In other words, the gold-rich alloy gradually gets richer in silver, and by successive single atom changes it becomes a pure silver nanoparticle. Similarly, the silver-rich alloy gradually becomes richer in gold and becomes a pure gold nanoparticle.

This chemistry occurs between a 25-atom piece of gold protected by molecular groups called ligands and a corresponding silver piece composed of 25 atoms of silver and the same number of ligands. These two nanoparticles, also called clusters, are made separately in solution.

Various alloys can be made and their composition can be controlled by controlling the ratio of the two clusters used. “The properties of alloys with different composition could be very new. We do not know what such capabilities give us,” he says. “The most fascinating aspect of this science is that it demonstrates the molecular nature of nanoscale matter.”

Related stories and links:

IIT Madras researchers’ cheaper solution to make brackish water potable

With $18 million venture funding, IIT Madras Prof breaks the glass ceiling

IIT Madras: A novel way to produce safer drinking water

IIT Madras: Affordable water purification using silver nanoparticles

IIT Madras: Graphene nanoribbons produced by a novel method

IIT Madras researchers dissolve silver using glucose water

IIT Madras: Designer alloys by chemical reactions

IIT Madras: Graphene nanoribbons produced by a novel method

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Published in The Hindu on November 10, 2016