MUMBAI : With advances in electron micrography, scientists are encountering a whole new world of special effects in the everyday reality of soap suds, soaked fabrics and unsolved crimes, say experts who met at the Electron Microscope Society of India's silver jubilee conference held last week at the Indian Institute of Technology (IIT), Powai.

"As soap dissolves in water, myriads of interwined 'snakes' grow from it," says Jayesh Bellare, conference convener and professor of Chemical engineering at IIT. "Unlike sugar, which dissolves molecule by single molecule, soap dissolves as a large collection of molecules arranged in multi-layered serpentine tubes. It's these tubes that give soap its characteristic slippery feel and help deliver detergents onto the fabric for cleaning applications," he adds. "This secret world of soap suds systems, which has been unveiled by new advances in electron microscopy, has vital applications in the areas of drug delivery and cellular modelling."

Similarly Dr. Firuza Parikh of Reliance Life Sciences, who was chief guest at the conference, stresses the importance of the new microscopic techniques in biomedical engineering, agricultural technology and the development of novel drug delivery systems. "The electron microscope is especially useful in the study of embryonic stem cells, in our quest to find out how these 'cellular blank slates' orchestrate themselves into specialised tissues of the body," she explains. "The insights gained will have a tremendous impact on the treatment of burns patients, diabetics and those suffering from a variety of diseases like Parkinson's and Alzeimer's. The market in these areas is worth billions of dollars and the work in these areas is capable of catapulting India to the forefront of science and technology. Collaborations with IIT are also on the anvil."

The electron microscope has become so useful today because it takes viewers into realms where light microscopes cannot hope to tread. It uses a beam of electrons instead of photons to look at objects with resolutions of 0.15 nm or 1.5 Angstroms that are unimaginable with the best of optical microscopy. At such magnifications, the human hair is seen to be as wide as a football field - and a pinhead would be large enough to accommodate one lakh people.

Seen under the IIT's latest electron microscope, for example, the eye of the humble housefly turns out to be a dazzling façade of geometrically perfect hexagonal arrays. Similarly, the butterfly owes the colourful intensity of its wings to zillions of tiny prisms. "It's pure microgeometry which diffracts light, and not pigments that's responsible for the butterfly's enticing colours," says Mr. Bellare, who is also head of IIT's biomedical engineering department. The latter discovery has led to a whole new industry of so-called 'structured colourants' that are far more enviornmentally friendly than conventional dyes and pigments.

Although electron microscopy was invented in the 1930s, significant improvements continue to take place, affecting virtually every field of science and medicine. Says G.B. Mathur, director of the Defence Material and Stores Research and Development Establishment at Kanpur, "Until now, the main limitation of electron microscopes was the need to dry the sample or fill it with colloidal materials so as to make it compatible with the high vacuum needed for free electron movement. A second limitation has been the need to avoid motion. That means only static images were possible, and this ruled out the study of dynamic processes. The latest and path - breaking developments of sample preparation in this field have overcome these limitations".

The new techniques are based on cryogenic microscopy and environmental microscopy or high-pressure microscopy. "These have overcome the earlier handicaps by giving us the ability to see structures such as the structure of water and that of specimens embedded in water," Mr. Mathur adds. "This was never thought to be possible before. 'Wet electron microscopy' has in turn, caused a great impact on biomedical engineering, virology, and chemical engineering," he avers. "With this technique we can easily see nanoparticles, membranes and cell-prototypes. Recent work shows that even everyday ordinary objects show remarkable microscopic behaviour."

Says IIT director Ashok Misra, "Today's electron microscopes are even being used on production lines and are designed to function automatically. They are routinely used, for example, to analyse microelectronic devices at the end of the production line for defects because no other tool is capable of providing blow-ups of the extremely densely packed circuits in modern microchips."

According to Mr. Misra, electron microscopy will strengthen the existing industry-IIT bonds and will also forge links under the aegis of the newly established school of Bioscience and Bioengineering at IIT, which has several electron microscopes including a cryogenic scanning electron microscope.
 
 
 

Mumbai : Electron microscopy has revolutionised the whodunit world of Miss Marples and Hercule Poirots, say experts at the recently concluded three-day annual conference organised by the Electron Microscope Society at the Indian Institute of Technology, Powai. "In addition to their field magnifying glasses, 21st century's Sherlock Holmes and Dick Traceys use a scanning electron microscope in the backroom," says conference convener Jayesh Bellare, who was recently appointed as head of IITs brand new school of Biosciences and Bioengineering named after Bhupat and Jyoti Mehta.

A scanning electron microscope (SEM) illuminates tiny objects with a focused beam of electrons instead of visible light. It reveals such things as tool marks, pits, fracture patterns and bullet markings as well as latent fingerprints.

According to experts higher magnification and greater depth of field are the two major advantages that a scanning electron microscope offers over its conventional optical counterpart. Says Dr. M.S. Rao, chief forensic scientist at the central home ministry's bureau of police research and development in New Delhi, "At higher magnifications, many vital details may become evident, which can help in establishing a specimen's origins."

He cites a case of thallium poisoning that was solved with electron microscopy. "The poisonous salt was expertly introduced into a soft drink bottle which was recapped," Dr. Rao explains, "Visual examination did not reveal any marks of tampering on the bottle or the cap. Micrographs obtained with a scanning electron microscope, however, clearly showed microscopic tell tale marks. Based on these, the defendant was convicted."

He cites another case, in which the defence pleaded that the gunshot residue used to book the defendant was in reality residue from an automobile exhaust. This was disproved by electron micrographs that showed up lead, antimony and barium - the trace metals usually found in gunpowder - on the defendant's hand. (Barium-tin-lead fused particles with characteristic shape are unique to gunshot residue, whereas car exhaust does not contain such alloyed particles.)

In yet another case, a murder victim was dragged along a carpet. In the process, some carpet fibres became lodged on the victim's body and clothing. Electron microscopy helped establish the unique identity of the carpet fibres and matched them to the scene of crime. Further analysis of the fibres with infrared spectrometry and thin-layer chromatography greatly increased the chances of conviction. Similarly, microscopic diatoms found in a murder victim's lungs and shoes were traced to a particular lake in Switzerland, helping the police to nab a peadophile serial killer thanks to electron microscopy.

The greater depth of field of the SEM is also extremely important, according to Anand Rao of Mumbai-based Icon Analytical. "In an optical microscope, objects are only in focus in the shallow plane of higher magnification, which can make the examination of specimen difficult," he says. "With its analytical capabilities, the SEM has become an indispensable tool in the modern crime-buster's kit. The electrons used to illuminate an object interact with its atoms, causing them to give off X-rays that a solid-state detector can pick up. Because each element emits X-rays at a unique set of energies, a plot of the number of X-rays emits at each energy level reveals the chemical composition."

Experts say electron microscopy, especially with cryotechniques, also provides chemical analysis with minimal sample preparation. This is essential to prove to the courts that there has been no tampering with the evidence, "because even the simplest sample preparation can often be construed as evidence of manipulation," Dr. Rao adds. "Usually, small amounts of evidence are all that is available at the crime scene. So, electron microscopy becomes all the more important when the usual methods feasible. Since preparation techniques like coating of the sample are deemed to be too intrusive, newer developments like cryotechniques (available at IIT-Mumbai) and the so-called environmental scanning electron microscopes (ESEMs) - displayed at the IIT conference - offer a way out." Says Hans Krussman, a SEM forensic expert from the Netherlands, "The ESEM can directly 'see' wet samples with minimal sample preparation. This makes it an indispensable tool for today's medical detective." He was showing off the use of a state-of-art ESEM machine for paint chip analyses at the IIT conference that marked the silver jubilee of the Electron Microscope Society of India.

Image: "SONS' OF SHERLOCK : Today's high-tech detectives use powerful tools like the scanning electron microscope.

IIT Powai has imported an electron microscope for the Electron Microscopy and Allied Fields seminar, which it is hosting. The special microscope has been brought in from Holland for two weeks and costs Rs. 2 crore. It is useful in forensics, aviation, atomic research and biomedical engineering. It is capable of magnifying an object up to a million times. PRASHANT NAKWE photographed a mosquito under different stages of magnification.

Image: The electron microscope apparatus and (inset) the plate on which the object to be magnified is placed.

The mosquito magnified 50 times its original size.

The mosquito head magnified 150 times.

The mosquito antenna magnified 1,500 times and (right) 3,000 times.
 
 

For more infrmation, Contact Prof. Bellare at: jb@iitb.ac.in