Common examples of these prefixes are Gigalitres – water reservoirs Megalitres – swimming pools Micrometres – measuring cells under the microscope Nanometres – size of large molecules Emphasize the correct use of prefixes – ML and mL are very different μ m – discuss the use of Greek alphabet in scientific work
An atom of gold is about 0.288 nanometers in diameter, so the gold nanoparticles are only several times the diameter of a single gold atom. These particles stay suspended in pure deionized water and do not fall to the bottom. It is these suspended particles that make a true colloid .
The ancient Romans were among the world's first nanotechnologists. They worked out how to make red glass using a process that converted gold metal into particles about 10 nanometres across. On this tiny scale - a nanometre is a billionth of a metre, or one-millionth of the size of a pinhead - gold changes colour and glows ruby red. Today, nanotechnologists are trying to exploit - as the Romans unwittingly did - the strange properties of matter, such as new colours, or altered electrical conductivity, strength, or magnetism, that occur when materials are engineered on an extremely small scale
Background information on the Lycurgus cup can be found on the following website: http://www.britishmuseum.org/explore/highlights/highlight_objects/pe_mla/t/the_lycurgus_cup.aspx Or watch the beginning of video 1 for more details Dichroic glass - This extraordinary cup is the only complete example of a very special type of glass, known as dichroic, which changes colour when held up to the light. The opaque green cup turns to a glowing translucent red when light is shone through it. The glass contains tiny amounts of colloidal gold and silver, which give it these unusual optical properties.
At those small sizes, gold no longer glitters gold. Electrons at the surface of the nanoparticles slosh back and forth in unison, absorbing blue and yellow light. But longer-wavelength red light reflects off the particles and passes through the window. Similarly, nanoparticles of silver in stained glass give a bright yellow hue. With much more sophisticated tools, scientists today can make nanoparticles of many more different shapes and sizes. Larger gold spheres appear green or orange; smaller silver ones are blue.
Rapid Meningococcal Diagnostic Test Announced http://www.azonano.com/news.asp?newsID=5166 In a world first, Victorian nanotechnology venture Quintain NS has announced a rapid meningococcal diagnostic test. The test will ultimately allow detection of meningococcal disease in less than fifteen minutes compared to the current tests, which can take up to 48 hours. Quintain NS meningococcal test An announcement regarding the filing of a worldwide patent has been made at the AusBiotech national conference in Brisbane. Meningococcal disease affects 700 people in Australia each year. The morbidity rate for those infected with meningococcal disease is 10 per cent, with death often occurring within 12 hours. Around 20 per cent of those affected will have permanent disabilities. The incidence of death and disability resulting from meningococcal disease may be significantly reduced by rapid diagnosis, which would enable antibiotic treatment to be administered at an earlier stage of disease progression. The currently available tests take between 2 and 48 hours, and often involve culturing either blood or cerebrospinal fluid to detect the presence of meningococcal bacteria. The new test has been developed by Quintain NanoSystems (Quintain NS), a vehicle established from Nanotechnology Victoria, a Victorian State Government initiative to assist in the commercialization of nanotechnology research. Nanotechnology exploits phenomena characteristic of materials at a scale of one billionth of a meter. Nanotechnology is likely to revolutionize the medical diagnostics and therapeutics industries over coming decades. The Quintain NS meningococcal test is based on nanoparticle and nanocluster technology developed at RMIT University , one of Australia’s leading bioengineering centres. Nanoparticles of gold are covered with antibodies that attract a protein present on the surface of meningococcal bacteria. In the presence of the meningococcal bacteria, the gold particles ‘cluster’ together. This causes an immediate colour change, providing a simple means of detection for the disease. Dr Jeanette Pritchard, who is leading the diagnostics and imaging activities for Quintain NS, says: “The completion of this patent is an important milestone. The RMIT team has developed a suite of outstanding technologies, with the potential to address many diseases; meningococcal is the first. Filing of provisional patents will protect the Australian invention and we expect that the meningococcal test will be available within 2-3 years.” Dr Anna Lavelle, CEO of AusBiotech, said that the launch of the technology at the AusBiotech Conference in Brisbane will bring it to international attention. “We have some very senior people from the world’s biggest pharmaceutical companies coming to Brisbane to see just what Australia has to offer – and Quintain’s invention is just what we excel at – clever technology that is world class,” she said. Dr Peter Binks, CEO of Nanotechnology Victoria, attributed the success to the development team: “This is a great achievement, and tremendous credit should go to the team at RMIT University – Professor David Mainwaring, Dr John Fecondo, and Eddie Grixti – and the NanoVic team – Dr Jeanette Pritchard, Dr Michelle Critchley, and Dr Bob Irving. The combination of superior research from RMIT and commercial orientation from the Quintain team has accelerated the development of a product of real importance to the community”. A prototype device for meningococcal diagnosis is under development.Quintain has combined with leading Melbourne Design house Charlwood to produce a set of novel devices, making the test safe and easy to perform. The devices will be completed by the end of November. Posted 23rd October 2007
Module Outcomes <ul><li>Have an awareness of origins/history of gold as a precious metal and its use in medieval times </li></ul><ul><li>Have an understanding of bulk properties of gold (including metallic structure) </li></ul><ul><li>An awareness that properties of gold change at the nanoscale </li></ul><ul><li>Understand how gold nanoparticles are produced in a school laboratory </li></ul><ul><li>Define a colloidal solution </li></ul><ul><li>Explain why gold has different colours in stained glass windows (in terms of size and shape of nanoparticles) </li></ul><ul><li>Have an appreciation of how gold nanoparticles are being used in medical applications. </li></ul>
Gold Is Valuable <ul><li>• Gold is a soft metal usually alloyed in jewellery to give it more strength, and the term carat describes the amount of gold present (24 carats is pure gold) </li></ul><ul><li>• Gold for jewellery can be given a range of hues depending on the metal with which it is alloyed (white, red, blue, green etc.) </li></ul><ul><li>• Jewellery consumes around 75% of all gold produced. </li></ul>Use in Jewellery Images top to bottom: Steve Evans @ flickr, jamesgroup @ stock.xchng
Gold Is Valuable Other uses <ul><li>Metallic gold is applied as a thin film on the windows of large buildings to reflect the heat of the Sun's rays </li></ul><ul><li>Gold electroplating is used in the electronic industry to protect their copper components and improve their solder ability. </li></ul>
Activity 1 <ul><li>What do we know about gold? </li></ul><ul><li>Describe the bulk properties of gold </li></ul><ul><li>Where is gold positioned on the periodic table? To which group does it belong? </li></ul><ul><li>Using a box of oranges and a bag of smarties describe the metallic structure of gold. </li></ul>Images top to bottom: José Luis Sánchez Mesa @ flickr, Craig Jewell @ stock.xchng
Understanding The Properties of Gold Properties of Metals <ul><li>lustrous–they have a shiny surface when polished </li></ul><ul><li>Malleable–they can be hammered, bent or rolled into any desired shape </li></ul><ul><li>Ductile–they can be drawn out into wires </li></ul><ul><li>good conductors of heat and electricity </li></ul><ul><li>generally have high densities </li></ul><ul><li>have a range of melting points but most are quite high </li></ul><ul><li>are often hard and tough with high tensile strength , meaning that they offer high resistance to the stresses of being stretched or drawn out and therefore </li></ul><ul><li>do not easily break. </li></ul>
Understanding The Properties of Gold So that’s bulk gold, BUT… Are the properties of gold the same at the nanoscale?
Experiment 1 Making Gold Nanoparticles <ul><li>Watch Video 1 and then conduct the experiment. </li></ul>Image: Courtesy RMIT and St.Helena
What Is Colloidal Gold? <ul><li>Colloidal gold is nanoparticles of pure gold suspended in water or a solution. The particles are approx a few nanometers in diameter (approx 10 to 50 nm) </li></ul><ul><li>These particles are so small they can only be seen by the most powerful electron microscopes available today </li></ul><ul><li>If you shine a laser beam through the colloidal solution the particles will scatter light. </li></ul>
What Is A Nanoparticle? A nanoparticle is an entity with a width of a few nanometers to a few hundred, containing tens to thousands of atoms. Image: Schatz Group, Northwestern University
Calculating The Size Of The Nanoparticles Images: Schatz Group, Northwestern University Watch Video 2 on calculating the size of nanoparticles. <ul><li>List and briefly explain the three methods used to determine the size of gold nanoparticles </li></ul><ul><li>Which method is the most accurate? </li></ul>
Gold Has Been Around For Ages Image: Courtesy F. Calati <ul><li>Medieval artisans were the first nanotechnologists </li></ul><ul><li>They made stained glass by mixing gold chloride into molten glass </li></ul><ul><li>They created tiny gold spheres, which absorbed and reflected sunlight in a way that produces a variety of colors </li></ul><ul><li>They knew that by putting varying, tiny amounts of gold and silver in the glass, they could produce the effects found in stained-glass windows. </li></ul>
The Lycurgus Cup Image: British museum The Lycurgus Cup made by the Romans dates to the fourth century AD. One of the very unusual features of the Cup is its colour . When viewed in reflected light, (in daylight) it appears green . When a light is shone into the cup and transmitted through the glass, it appears red . Optional Research activity: Dichroic glass was used to make this cup, find out what property this glass has.
Size & Shape Determines Colour Images: Dr. Chad A. Mirkin, Northwestern University Gold particles in glass 25 nm — red reflected 50 nm — green reflected 100 nm — orange reflected
Colour <ul><li>• Nanoparticles often have unexpected visible properties because they are small enough to scatter visible light rather than absorb it </li></ul><ul><li>Gold nanoparticles appear deep red to black in solution. In fact a whole range of colours can be observed depending on the size of the gold nanoparticles </li></ul><ul><li>The distance between particles also effects colour. Surface plasmon resonance is the term used by nanotechnologists to describe this effect. </li></ul>Optional Research activity: Surface Plasmon Effect 5nm clusters of Gold
Bulk Gold Vs Nano Gold <ul><li>Is shiny </li></ul><ul><li>Always gold in colour </li></ul><ul><li>Is inert </li></ul><ul><li>Conducts electricity </li></ul>Bulk Gold <ul><li>Vary in appearance depending on size and shape of cluster </li></ul><ul><li>Are never gold in colour </li></ul><ul><li>Are found in a range of colours </li></ul><ul><li>Are very good catalysts </li></ul><ul><li>Are not “metals” but are semiconductors. </li></ul>Gold Particles
What If? … you could use gold to detect meningococcal infection before it progressed too far? Image: Courtesy of Meningococcal Education, meningococcal.org
You Can! Image: Courtesy of Nanotechnology Victoria Pty Ltd Victorian nanotechnology venture Quintain NS is working on a meningococcal diagnostic test that uses gold nanoparticles. The test allows for detection of meningococcal disease in less than fifteen minutes compared to the current tests which can take up to 48 hours .
Using Nanogold in Diagnosis Image: Courtesy Bridge8/Flinders University <ul><li>What happens when salt is added to the red gold nanoparticles? </li></ul><ul><li>What does the animation demonstrate? </li></ul>Watch Video 3 on the coupling of gold nanoparticles
Why All The Fuss Over Nanogold? <ul><li>They offer promise in medicine . </li></ul><ul><li>For sensitive diagnostic tests and novel treatments in the detection of Alzheimer’s disease by finding a protein in spinal fluid </li></ul><ul><li>Nanobullets that heat up and kill cancer cells </li></ul><ul><li>They offer promise in computing/electronics/printing </li></ul><ul><li>In data storage where gold nanoparticles will be used to increase the speed at which data can be written </li></ul><ul><li>Nanogold Conductive Inks. </li></ul>
Revision <ul><li>What is a gold nanoparticle? </li></ul><ul><li>What are the traditional ways for synthesizing gold nanoparticles? </li></ul><ul><li>How do you determine the size of a gold nanoparticle? </li></ul><ul><li>Why are gold nanoparticles so important in medical research? </li></ul>