2008 Kavli
Prize in
Nanoscience

Citation from the committee

When the electronic motion in a solid is confined to zero or one dimension on the nanometer scale, its functional properties can be dramatically altered. This makes nanostructures a subject of both fundamental and practical interest. On this scale, corresponding to the dimension of a few atoms, quantum effects change and lead to unexpected and technically interesting properties. Among the many structures investigated in the last few decades, carbon nanotubes and colloidal nanoparticles have proven to be promising quantum structures in physics, chemistry, and biology, and are actively explored in many research laboratories worldwide.

Louis Brus created the interdisciplinary field of colloidal semiconductor nanocrystals, through original discovery, theoretical modelling, chemical synthesis of purified samples, and by studying the spectroscopy of individual nanocrystals. His research, leadership, and mentoring have played a leading role in opening world-wide interest in colloidal nanomaterials with controlled size-dependent properties. The results of his studies have led to a surge of activities by many researchers in the field in the areas of synthesis and the application of these colloidal nanoparticles in many areas of chemistry, biology, and medicine, a few examples of which are discussed below.

Colloidal semiconductor nanocrystals, commonly called quantum dots (QD), have a number of properties such as the dependence of their fluorescence wavelength on size and their long-time stability. This makes them suitable for fluorescence based dynamic studies of molecular interactions and reactions in biological systems.

There is considerable interest among researchers due to the recent developments in binding colloidal nanocrystals to tumor-targeting antibodies or as drug delivery agent for targeting, imaging, and treating tumor cells. Present efforts are focused on exploring the multiplexing capabilities of the QDs for the simultaneous detection of multiple cancer biomarkers in blood assays and cancer tissue biopsies. These advances in the QD technology have unravelled a great deal of information about the molecular events in tumor cells.

In the solar energy field, photovoltaic cells using QD-polymer composite may offer advantages such as mechanical flexibility, low cost, and hopefully increased efficiency.

Success in making proof-of-concept quantum dot displays has been achieved. They are useful because they emit light in very specific spectral distributions that can be selected in a display which can more accurately render the colours that the human eye can perceive.

Sumio Iijima prepared a new type of finite carbon structure consisting of needle-like tubes using an arc-discharge evaporation method. He also did careful electron microscopic analysis of the structure that revealed that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube, the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. From this detailed structural analysis, he has pointed out to many future applications of these nanotubes.

They have interesting mechanical, electrical, and thermal properties. They are much stronger than steel at one sixth of the weight. For these reasons, they are used in the re-enforcement of mechanical strength of composite materials ranging from everyday items like clothes and sports gear to construction materials such as cement. The electrical and thermal properties of nanotubes change with their diameter and are sensitive to the way the nanotube is formed. Depending on their atomic structure, they can have semiconducting or metallic properties. For this reason, they have potential use as electronic components such as diodes and transistors, wires, transparent and conductive films; electrodes for super-capacitors; field emitters for displays; and sensor applications. The functionality of nanotubes can be expanded by filling them with active atoms and molecules for various future uses.

Colloidal semiconductor nanocrystals and carbon nanotubes will thus play a key role in the future various applications of nanoscience in the fields of energy, environment, electronics, chemistry, composite materials, and bio-medicine.

In 2007, Sumio Iijima received the International Balzan Prize for Nanoscience.

The 2008 Kavli Prize in nanoscience explained

The creation of new technologies through the manipulation of materials at the atomic level is widely predicted to revolutionize a wide range of industries in the near future. Announcements of advances in nanoscience are made almost weekly by scientists from across the world.

By Nic Fleming, Science writer

In making their award, the Kavli Nanoscience Prize Committee has selected two scientists without whose pioneering work subsequent developments with huge implications in the fields of energy, the environment, electronics, chemistry, composite materials, and bio-medicine would have been impossible.

Louis E. Brus, of Columbia University in the U.S., made a fundamental discovery in 1983 while studying the optical properties of semiconductors whose atoms or molecules had been excited by the absorption of light.

Unlike traditional semiconductors such as silicon, Brus made water-based suspensions of tiny semiconductor particles and noticed that they took on unusual properties depending on their size and shape. Collaborating with colleagues, Brus made smaller and smaller synthetic particles, and by the mid-1980s he realized these colloidal semiconductor nanocrystals, now commonly known as quantum dots, could prove highly useful in a variety of fields.

Quantum dots have a number of interesting and potentially useful properties. The color of light they emit when under UV light varies according to their size. This, and their long-term stability, make them ideal for use as markers to study molecular interactions and changes in biological systems.

Whereas the organic dyes currently used to track the development of tumors or the precise mechanism of a drug in the body may last for only hours or days, quantum dots can remain useful for months or even years. As a result of Brus’ pioneering work, hundreds of teams of scientists are investigating the use of quantum dots in medical applications such as early cancer identification, tumor imaging, and drug delivery.

Others are using them to develop computer displays that are more efficient and accurate alternatives to traditional models, and advanced, low cost photovoltaic cells with increased flexibility and efficiency.

Physicist Sumio Iijima, of Meijo University, Japan, is widely known as the scientist who discovered carbon nanotubes. These structures and their properties had been studied prior to his landmark publication in Nature 17 years ago; however, his work triggered unprecedented interest and further research in the subject.

After attending a conference at which he discussed the recent discovery of novel forms of carbon with some of the pioneers in the field, Iijima returned to Japan to build on his previous work in the field. His "eureka" moment came on June 23, 1991 while examining crushed soot formed as a result of applying an electric current to carbon rods. Peering down his microscope, he noticed the resulting carbon forms were arranged in needle-like tubular structures. Hexagons of carbon atoms formed spirals of varying pitch around the axis of each needle.

Iijima’s expertise in the use of electron microscopes helped in his detailed structural analysis of these nanotubes and allowed him to rapidly recognize a wide range of potential applications. They are many times stronger than steel at one-sixth of the weight. Researchers have already exploited this to develop a prototype bullet-proof vest, and others are using them in composite materials to improve the strength and durability of everyday items as diverse as sports equipment and construction materials.

The electrical and thermal properties of nanotubes vary according to the way they are created and their diameter. Depending on their atomic structures they can have semiconducting or metallic properties, meaning they have potential uses in the production of conductive plastic films and electronic components such as diodes, transistors, and electrodes.

Iijima has continued his research in nanotubes, learning how to manipulate them further, and is working to harness their unique properties as hydrogen storage vessels in fuel-cell batteries.

Professor Arne Skjeltorp, of the University of Oslo and chairman of the Kavli Nanoscience Prize Committee, said, “Nanoscience deals with the very building blocks of nature. The biological systems that surround us are full of nano-scale systems and components. In the course of the evolutionary process, nature has, over millions of years, developed numerous solutions for robustness and adaptability, including sophisticated mobility and self-healing mechanisms, highly sensitive sensors, and complex information and communication systems. Many leading scientists believe our urgent needs in the fields of energy, the environment, health, and technology can be addressed by learning from nature. Brus and Iijima created prototype nanoscale building blocks in zero and one dimension, as "dots" and "tubes," in the chemistry and physics arenas. They both looked for and found something new along the long road toward creating our own version of smart biological solutions.”