gold and nanotechnology in the age of innovation

8/3/2019 Gold and Nanotechnology in the Age of Innovation

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GOLD FOR GOOD

Gold and nanotechnology in the age of innovation


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Gold and nanotechnology in the age o innovation

Executive summary 3

Introduction 5

Gold or health 7

Gold or the environment 11

Gold or technology 15

Where next? 18

Contents

January 2010


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GOLD FOR GOOD

Gold and nanotechnology in the age of innovation

Authors:Dr Trevor Keel World Gold Council

Dr Richard Holliday World Gold Council

Dr Tim Harper Cientifca

Executive summary

Nanotechnology oers the potential to overcome

many o the serious issues acing mankind overthe coming decades. Climate change, pollutioncontrol and prevention, access to clean water,alling energy reserves and the diagnosis andtreatment o diseases such as cancer all representsignicant challenges to man and the planet. Newscientic and technological breakthroughs will beneeded to deliver solutions. Over the last decadealmost $50 billion o government unding has beeninvested into nanotechnologies, and this investmentis now starting to bear ruit with a steady stream ocommercially viable nanotechnologies which arepositively impacting human health, the environmentand technology.

Gold is at the oreront o this nanotechnologyrevolution. Gold nanoparticles exhibit a varietyo unique properties which, when harnessed andmanipulated eectively, lead to materials whoseuses are both ar-ranging in their potential and cost-eective. Gold or Good Gold and Nanotechnologyin the Age o Innovationhighlights the rich, ascinatinghistory and exciting uture o gold nanotechnologyand explores the answers to two questions; why isgold so unique and useul at the nanoscale and,

most importantly, what applications can it be usedin or the wider good o society.

The earliest medical uses o gold can be tracedback to the Chinese in 2500BC. Yet it has been thedawn o the nano-age that has really broadened thepotential o gold in biomedical applications. Tumour-targeting technologies which exploit golds inherentbio-compatibility are being developed to deliverdrugs directly into cancerous tumours. Additionally,simple, cost eective and sensitive diagnostic testsare being developed or the early detection o

prostate and other cancers.

Gold nanoparticle-based technologies are also

showing great promise in providing solutions toa number o environmentally important issues,rom greener production methods o the chemicaleedstocks we need to produce our everydaygoods and oodstus, to pollution control and waterpurication. For example, gold-based catalysts arebeing developed that can eectively prevent therelease o highly toxic orms o mercury into theatmosphere. The metal is also being used in meetingthe challenge o constructing cost eective andecient uel cells, a key clean-energy technologyo the uture.

As the worlds o electronics and nanotechnologyincreasingly interact in the uture, it seems highly likelythe electronics industrys use o gold as a criticalmaterial will continue. Gold is being developed orconductive nanoparticle inks or plastic electronicsbecause o its material compatibility, inherentdurability and proven track record o reliability. Goldnanotechnologies have also been shown to oerunctional benets or visual display technologieslike touch sensitive screens and potentially or usein advanced data storage technologies includingadvanced fash memory devices.

Clearly gold is at the very core o many scienticand commercial breakthroughs in nanotechnologywhich are having a positive impact on lives aroundthe world. This paper serves to illustrate boththe progress to date and the bright uture o goldnanotechnology in a range o vital elds.


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What is nanotechnology?

Nanotechnology is a relatively recent branch oscience concerned with controlling the propertieso materials by working on the scale o a ewnanometres, or the size o a ew atoms. The mostimportant aspect o nanotechnology is that it is abottom up technology. This means that instead otaking our usual top down approach, we work ina way that is closer to the method nature uses or

creating materials.

Humans have spent the last twenty thousand yearstaking materials that they nd in the environment andorcing them to do something useul. I we wanted tocut something, we initially used shards o fint, andthen progressed through bronze, iron and steel todiamond coatings. I we wanted to store inormationwe moved rom papyrus to paper and eventually tosilicon.

By contrast, nature takes a bottom up approach,and builds the perect materials or the job. Forexample, DNA or data storage, or a sel healingsupport structure or our bodies called bones, thatwhile rigid, is fexible enough to absorb most o theknocks and tumbles we suer during our liespan.

While nature has evolved these materials overthree billion years o random evolution, starting atthe bottom rather than at the top has been thedream o scientists and engineers or over tyyears. Finally, with our combined understanding omaterials science, biology, physics and chemistry,nanotechnology is helping us create materials and

processes that are driving the development o arange o ever more sophisticated, eective andsustainable solutions to key issues aecting humanhealth, the environment and technology.

Gold and nanotechnology

Gold has been regarded as precious or as long ashumans have existed, and has been associated withgods, kings and immortality. Today, nanotechnologyis enabling gold to help address critical globalproblems rom cancer treatment to climate change.

Although nanotechnology is thought o as a newbranch o science that has only emerged over the

past decade, gold nanoparticles have been used,albeit unwittingly, or several thousand years. Romanartisans knew that mixing gold chloride into moltenglass, a technique that produces tiny gold spheres,gives the glass a rich ruby colour (or possibly mauvei a combination o larger and smaller particles areproduced). This technique produced much o thered colour in glass items rom the amous LycurgusCup to stained glass windows o cathedrals acrossEurope.

O course these ancient artisans were not awarethat the optical properties o gold change when youcreate particles a ew nanometres in diameter. Ourmodern concept o chemistry was totally unknown,and the primitive chemistry o the time, or alchemyas it was known, was more concerned with ndingways o turning more common elements such aslead into a big lump o gold, rather than nding newuses or gold.

Although nobody realised it at the time, there was akind o alchemy going on, one that involved usingsmall amounts o gold to produce something omuch higher value than its constituent parts.

The next major step in the development onanotechnology, in 1857, again involved gold whenMichael Faraday ound that gold colloids (solutionsthat contain a suspension o tiny particles) hadspecial optical and electrical properties. Faradayused phosphorous to reduce gold chloride, whichonce again produced a suspension o goldnanoparticles. While Faraday and others developedtechniques or reliably producing colloidal gold(vigorous stirring seemed to do the trick) the submicron world was still a mystery, and although

properties o gold nanoparticles could be observedand measured, nobody was quite sure why theybehaved in this way.

Introduction


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With these ancient methods o producingnanoparticles, there was little control over the size

o particles created and their concentrations butit worked well enough or its day. But in the era omicroscopes so advanced we can see individualatoms, and o computers so powerul that we canmodel the behaviour o chemicals without settingoot in a lab, the applications o gold nanoparticlesare expanding at an ever-increasing pace.

While gold cannot grant immortality, it can be usedto understand the nature o diseases like cancer andto provide highly targeted treatments, and it can helpto create cleaner vehicles and greener chemistry to

reduce the environmental burden on the planet. Thisreport explores the answers to two questions; whyis gold so unique and useul at the nanoscale and,most importantly, what applications can it be used inor the wider good o society.

Gold nanoparticles were once usedto colour stained glass windows


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Gold for health

Gold has a long, ascinating history in the biomedicaleld stretching back almost ve thousand years.Unlike other metals it resists tarnishing, so gold haslong been associated with gods and immortality, andwas thereore naturally associated with health.

The earliest recorded medical use o gold can betraced back to the Chinese in 2500 BC and sincethen numerous ancient cultures have utilised gold-based medicinal preparations or the treatment o a

variety o conditions including smallpox, skin ulcersand measles. More recently, and with rather moresuccess, drugs containing gold have been used in thetreatment o rheumatoid arthritis and considerableresearch has gone into the potential anticancer andantimicrobial activity o gold compounds.

However, it has been the dawn o the nano-agethat has really broadened the potential o gold inbiomedical applications. The unique propertiesoered by nano-sized gold particles are currentlybeing studied in exciting and innovative academicresearch and exploited in a range o potentialproducts heading towards market.

Therapeutics

Whilst the use o gold in the treatment o diseasehas a long history, gold nanoparticles are nowbeing employed in entirely novel ways to achievetherapeutic eects.

The problem with many currently available cancertreatments is that they cannot be accurately targeted.As it is very hard to get an eective drug, such as

paclitaxel, directly to the tumour, large doses areneeded in the hope that enough o the drug will reachthe diseased cells where it is needed. Unortunatelythe drug doesnt distinguish well enough betweenhealthy and diseased cells, and a wide range o sideeects oten occur, sometimes making the treatmentseem worse than the disease.

However, i a way could be ound to deliver the drugonly to the cancerous cells, a much lower dose wouldbe required, healthy cells would not be aected andside eects could be dramatically reduced. This is

the basis o the movie Fantastic Voyage, which used

a miniaturised submarine to deliver the payload, butnanotechnology is allowing us to turn science ctioninto reality, and without the hassle o miniaturisingsubmarines.Probably the most advanced example is thato CytImmunes tumour-targeting technologyAurimune, which exploits golds inherentbiocompatibility and unique properties to deliver atherapeutic dose directly into cancerous tumours.

Whilst this may seem like the stu o science ction,CytImmune has successully completed Phase Iclinical trials (i.e. testing on a small group o peopleto conrm that the drug works as expected) and isabout to embark on wider-ranging Phase II trialswhere a much larger scale trial is conducted in orderto screen or any possible side eects that wouldhave been missed in the initial small group trials.

Another company making signicant progresstowards commercialisation is Nanospectra. LikeCytImmune, Nanospectra is utilising gold to treatcancerous tumours, but in a completely dierentway. The technology, called Aurolase, combinesthe unique physical and optical properties o gold-coated AuroShell particles with a near inraredlaser source to thermally destroy cancer tissuewithout signicant damage to surrounding healthytissue. This promising technology is currently inPhase I clinical trials.

Both companies are building pipelines o gold-based therapies, clear proo that the market andinvestors are encouraged by the clinical data seento date and excited by the uture potential o ered by

such technologies.

Diagnostics

Diagnostics is an area where nanotechnology,particularly using gold, has the ability to revolutionisethe way we deal with disease. Whether it is highlysensitive and low cost diagnostic tests that enablepeople to be screened or diseases with limitedearly symptoms such as prostate cancer, or rapidscreening or HIV. The earlier a disease is detectedthen the more eective (and cheaper) the treatment

will be, allowing highly targeted drugs to be usedinstead o surgery.


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Needleless vaccine delivery?

Gold-based technologies are also being exploited byleading pharmaceutical companies. In 2006, Pzer, theworlds largest healthcare organisation, purchased thesmall British DNA vaccine company PowderMed.

PowerMed had developed a unique needle-ree deliverysystem, a technique that used gold nanoparticles andallowed vaccines to be delivered through the skin makinguse o the act that small particles can pass through gapsbetween cells while large ones cannot.

Through early phase testing, PowerMed achieved promisinghuman in vivo data and had even shown the technology hadpotential or improved ecacy compared to more traditionalvaccine delivery methods. This technology remains anactive part o Pzers vaccine research programme today.

PowderMeds gold-based vaccine delivery system

The principles behind Cytlmmunes gold-based anti-cancer therapy

Anti-cancer drug

The therapeutic payload travels unhindered through thebloodstream and is delivered directly to the site o the tumour

Goldnanoparticles

Tumour

Blood cell

1

2

3

4

An anti-cancer drug is bound to gold nanoparticles

The tumour is treated, leaving the surrounding healthytissue largely unaected

The drug-loaded gold nanoparticles are injected intothe patient

Vaccine-coated gold nanoparticles are propelledinto the epidermis by a burst o pressurised helium

Epidermis


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Nanoparticulate gold is the perect raw materialor robust, rapid diagnostic testing. The minute

quantities required make it inexpensive, whilstits stability, sensitivity and reproducibility omanuacture guarantee high quality supplies arealways available.

Indeed, diagnostic applications utilising goldnanoparticles are already commercially available. TheFirst Response pregnancy testing kit, marketed byChurch & Dwight, employs gold nanoparticles boundto a specic DNA sequence which is sensitive tothe presence o a hormone indicative o pregnancy.Another example is the collaboration o BBInternational

and Merck in the design and development o varioustests or the detection o ood borne pathogens. TheMerck Singlepath assay uses gold nanoparticlesto detect the presence o salmonella within twentyminutes, while the Duopath assay can be used toidentiy a range o pathogens including salmonella,E. coli and Campylobacter. A comprehensive studyshowed that ood poisoning led to approximately5000 deaths annually in the USA alone [1], makingthe availability o reliable diagnostic tests important.

Gold nanoparticles in the battleagainst HIV/AIDS

According to the World Health Organisation,HIV inection in humans is considered to beat pandemic levels. Worldwide, over 33 millionpeople are believed to be living with HIV, with 2million suering an AIDS-related death in 2008alone [2]. As is oten the case, many o thesedeaths may have been preventable i access tothe appropriate diagnostics and therapies hadbeen more widely available.

The Bwindi Community Hospital laboratory sta withthe PointCare NOWTMdiagnostic system that uses goldnanoparticles

Spurred by this pandemic, pioneering work hasbeen undertaken by PointCare TechnologiesInc, a US-based medical diagnostics company.PointCare has a specic mission to providebetter diagnostic care to disadvantagedpopulations worldwide. Through thecommercialisation o technologies developedby scientists over the previous three decades,PointCare has bought to market two products AuRICA and PointCare NOW. Both diagnosticdevices rely on the unique properties o colloidalgold nanoparticles to allow the measurement oCD4 positive white blood cells. It is these cells

which are attacked and destroyed by the HIVvirus, so having an accurate measurement o theirnumber is key to knowing how advanced the viralinection is, and how best to begin treating it.

The real strength o this diagnostic test lies in itssimplicity and robustness. The colloidal gold itselis extremely hardy, making it suitable or long-termstorage and use in the typical Arican climate. Thediagnostic system is portable, simple to use, andprovides a readout within minutes meaning manytests can be perormed in remote locations.

More recently, the Illinois-based companyNanosphere has delivered a ully integrated

diagnostics platorm called Verigene to market.The Verigene system operates by detectingspecic biomolecule targets with gold nanoparticles.These gold-based probes are non-toxic, have a longshel lie and, most importantly, are extraordinarilysensitive. The system can be used to diagnose abroad range o conditions. In addition to a growingpipeline o gold-based diagnostics, Nanosphere alsohas a tie-up with Eli Lilly, one o the worlds leadinghealthcare companies, which utilises its gold-basedtechnologies in the eld o early drug discovery.

Medical diagnostics make up part o a valuable,rapidly-growing market in which gold is playinga signicant role. There are dozens o academic,start-up and industrial research groups around theworld working in the area, and we expect to seeurther market penetration in the coming years orthe technologies currently under development.


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0

The scourge o prostate cancer

can gold lead the charge?

Prostate cancer is the second-most commoncancer among men in the United States. It isestimated that more than 2 million Americanmen are currently living with prostate cancerand that one new case occurs every 2.7 minutes.According to the Prostate Cancer Foundation,more than 27,000 men die rom the diseaseeach year [3].

A major contributor to these considerablenumbers is the act that there are ew symptomsin the early stages o prostate cancer, meaningit is dicult to catch (and treat) the diseaseearly. Currently cancer tests are expensive andinconvenient, so a simple, cheap and sensitivediagnostic kit could potentially save many lives.

This is the target o US-based researchers

Proessor Qun Huo o the University o CentralFlorida and Dr Cheryl Baker o M.D. Anderson-Orlandos Cancer Research Institute. ProessorHuos work hinges on engineering goldnanoparticles to attach themselves to speciccancer-related proteins. When these proteinsare present in the blood, they sense the goldnanoparticles and orm clusters in the solution.It is these clusters that can be measured usinga technique called Dynamic Light Scattering,an extremely sensitive particle sizing method.I clusters are shown to be present, the patientcan be reerred to a doctor or urther testing andtreatment i necessary.

The World Gold Council recently providedsupport to accelerate the commercialisation othis promising technology [4].

NanoDLSay a one step immunoassay that uses gold nanoparticles or early-stage cancer detection

Antimicrobials

Silver has a long history o being used as anantimicrobial agent, and is used in a number omarketed products. Probably the best known o theseis the use o nano-silver impregnated dressings totreat wounds and prevent inections. However, theantimicrobial eectiveness o silver is known todeplete over time, meaning there is signicant scopeor improving such technologies. Researchers inGermany have dispersed a combination o gold and

silver nanoparticles into polymer lms. The presenceo gold nanoparticles has been shown to enhance

the long-term antibacterial action o the lms,probably by slowing the rate o silver ion release.A team at the University o London have alsodeveloped a gold nanoparticle basedphotosensitiser that dramatically enhancesantimicrobial eectiveness at small doses.This technology has been licensed to OndineBiopharma Corporation in Canada or continuedcommercialisation.

Goldnanoparticle

solution

Blood sampleremoved rom human

and added to goldnanoparticle solution

Sample isincubated and

analysed

The presence o the cancer-relatedproteins in the blood sample cause thegold nanoparticles to cluster together.

This clustering can then be identied

during the sample analysis

Cancer-relatedprotein

100 nm


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Gold for the environment

Environmental concerns have never been moreprominent. The world aces huge challenges inthe coming years as a consequence o ongoingpopulation growth, ever increasing energy needsand the threat o global warming amongst a host oother issues. Gold nanoparticle-based technologiesare showing great promise in providing solutions toa number o environmentally important issues, romgreener production methods to pollution control andwater purication.

Catalysts

The production o most industrially-importantsubstances and chemicals involves the use o acatalyst to improve the eciency and economics o theprocess. Size is important in catalysis as the reactiontakes place only on the surace o the catalyst.Getting the right catalyst can have numerousbenets to everything rom oil rening to automotiveemissions. Using nanoparticles can reduce theamount o precious metal required, and improvedcatalysts can both lower the temperatures andpressures required in some industrial processes, andimprove the selectivity o reactions. This can result inmore o the desired chemical being produced, andless waste.Gold, or many years, was believed to be o nopractical use as a catalyst, despite other preciousmetals like platinum and silver being widelyemployed. It was only in the 1980s that interest reallybegan to take o in the use o gold nanoparticlesas a catalyst in important chemical reactions. It is

the understanding and availability o such particlesthat have led to the exponential growth o interest ingold as a catalyst over the last couple o decades,even culminating in an entire book dedicated to thesubject [5].

There are many important chemical proceduresthat have benetted rom the availability o gold-based catalysts. Probably the most commerciallyestablished example is that o Vinyl Acetate

Monomer (VAM) production. VAM is a key ingredientin emulsion polymers, resins, and intermediates usedin paints, adhesives, coatings and textiles amongstothers. As an illustration o the industrial magnitudeo this process, British Petroleum commissioned aplant in the UK in 2001 or the large scale productiono VAM, and even developed a brand new gold-based catalyst in collaboration with Johnson Mattheyor use in the new acility. This plant, which has aVAM production capacity o a quarter o a milliontons per year, continues its operation today underthe ownership o INEOS, the worlds third largestchemical company.Gold is o interest in a variety o other commerciallyimportant reactions including the selective oxidationo sugars, the production o methyl glycolateand the water-gas shit reaction amongst others.Patent activity in these areas has been signicant,with most major petrochemical and ne chemicalmanuacturers involved.

Gold catalyst availability

To meet an increasing interest in using goldnanoparticles catalysts commercially, largerscale supplies o catalysts are now availablerom various sources. 3M has developed acatalyst which is now distributed by UK-basedCompany, Premier Chemicals, under the tradename NanAucatTM. The catalyst, which isnanoparticulate gold on a carbon substrate, ishighly ecient with low gold loading, making itcommercially viable. Mintek also supply gold-based catalysts on a range o supports underthe brand name AuroLITETM.

Environmental challenges will dominate the coming years - goldnanoparticles oer a number o exciting potential solutions


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Mercury control and sensing

Mercury is a highly toxic substance ound in smallground deposits all over the world. Approximately150 tonnes o mercury nds its way into theatmosphere every year, a third o which comes asa direct consequence o coal-red boiler emissions.As mercury has been linked to Alzheimers diseaseand autism, it is anticipated that the US EnvironmentalProtection Agency (EPA) is soon to impose stringentlimits on mercury emissions rom such boilers in theutilities industry [6]. Couple this with the act thatthe US is relying increasingly on the use o coal toproduce electrical power, it is clear that any stringent

limits could prove dicult (and costly) to meet.As such, there is currently a major ocus on identiyingmethods to more eectively prevent the release otoxic orms o mercury into the atmosphere.

Exciting new research is beginning to emerge whichsuggests that gold-based catalysts can provide asolution. Studies perormed at the US National EnergyTechnology Laboratory (NETL) in collaboration withJohnson Matthey have shown gold nanoparticles tohave considerable promise as mercury oxidationcatalysts. Full-scale trials are now underway in oneUS power station. Further research in this eld hasalso been supported by the World Gold Council at aleading European university [7].

The eectiveness o any technology solution to theabove problem will need to be measured. Here

too gold nanoparticles may play a role as there isconsiderable interest in using gold nanoparticles tosense and quantiy mercury levels. Researchersin Australia have developed such a sensor byengineering a gold surace to take the shape othousands o nano-spikes, which signicantlyincreases the surace area o the gold. This allowsthe surace to more eectively trap molecules omercury, enabling their number to be quantied.

Air quality

Carbon monoxide (CO) is a colourless, odourlessgas which is extremely toxic to humans and animals.CO poisoning can occur with alarming ease andspeed and exposure to even relatively low levels oCO can be atal, making the ecient removal o itrom closed atmospheres vital. Oten produced asa result o poorly ventilated boilers, CO poisoninghospitalises over 4000 North Americans every year,with 10% resulting in atalities [8]. Gold nanoparticlesprovide a simple solution, by allowing the oxidation oCO to carbon dioxide (CO

2), transorming an acutely

dangerous gas to a ar less toxic substance. What isstriking about gold nanoparticle catalysts is that theycan catalyse the oxidation o CO at extremely lowtemperature, even working at temperatures as low as-70C. This unique property opens up the potential touse cost-eective amounts o gold as a commerciallyviable CO oxidation catalyst in a range o domesticand industrial applications. For example, a number ocompanies have already developed respirators whichare required in emergency situations or protectingre-ghters and miners rom CO poisoning, andother applications are likely to appear soon.

Water purifcation

Our planet has no shortage o water, but it is unevenlydistributed with much o it being undrinkable due tosalinity or pollution. In some cases this is as a resulto industrial pollution, in others the local geologymeans that even well water contains signicant levelso heavy metals such as arsenic. However, heavymetals arent the only problem other commonpollutants include pesticides and halogenatedorganics. These are all prevalent chemicals in manyparts o the world, meaning literally millions opeople are at risk o being exposed to contaminated

drinking water.Monitoring and improving air quality around power stationsincludes control o mercury levels - trials are already under touse gold nanoparticles or this purpose


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Recent years have seen a sharp rise in the use onoble metal nanoparticles or water purication and

contaminant detection. In addition to demonstratinggreat potential or the oxidation o mercury in gasfues, gold nanoparticles have also been shown tobe ecient adsorbents or the removal o signicantlevels o mercury rom water. Other breakthroughshave included the development o catalyticallyactive bimetallic gold-palladium nanoparticles(which have shown real promise in breaking downtrichloroethene, a common organic groundwaterpollutant), and the development o simple detectionmethods to determine the concentration o pesticidesin drinking water.

Fuel cells

Fuel cells are already accepted as reliable clean-energy power sources or space and militaryapplications, and are now being developed or awide spectrum o alternative uses, including vehicles.Although widely demonstrated and technicallyproven, their cost needs to be reduced to make themtruly competitive in mass markets. It is here that goldnanotechnology is making a real impact.

One o the biggest technical challenges regardingthe construction o ecient uel cells is nding cost-eective materials that can withstand the corrosivecondition o the cell. Cells must be stacked togetherto achieve the necessary perormance and durability,and gold-coated stainless steel has been recognisedas the material o choice or these separator plates[9]. The only issue is cost what is required is areduced thickness gold coating which retains theperormance o a thicker coating.

Many large car manuacturers have been working onthis issue over the past ew years, and it seems that

the Ford motor company has made a considerablebreakthrough. They are developing metallic bipolarplate technology with thin gold-coated stainlesssteel (under the brand name Au Nanoclad)provided by Daido Steel [10]. They report that theuse o Au Nanoclad provides a cost eective wayo delivering the required electrical conductivityand corrosion resistance. Additionally, gold-coatedstainless steel shows anodic passivation, i.e thethin gold layer heals itsel, making it tolerant ocoating deects including surace scratches duringmanuacturing, and reducing production costs o

the bipolar plate.

Nanostellar Inc. Developing a newgeneration o autocatalysts

Proclaimed as a 2008 Technology Pioneer byThe World Economic Forum, Nanostellar Inchas developed a new catalyst product, NSGold, a ormulation or use in the automotiveindustry that, or the rst time, includes goldalongside traditional platinum and palladiummetals. Autocatalysts have historically usedplatinum group metals to control harmulelements in automotive exhaust; carbonmonoxide (a poisonous gas), hydrocarbons

(rom partially burned uel that gives o dieselor petrol odour), particulate matter (or smoke- which contains cancer causing compounds)and NOx (smog orming compounds). Theinclusion o gold, as a partial replacemento more expensive platinum, enablesmanuacturers o light and heavy-duty dieselengines to reduce these emissions at lowercost, making an important contribution touture automotive emissions control.

The World Gold Council (WGC) signed anagreement in December 2007 with Nanostellar.Under this agreement, the WGC invested toacilitate the commercialisation and marketingo the technology [11]. The viability ousing gold in this application has now beenrecognised by the industry [12].


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4

Energy-efcient glazing coatings

Since the 1960s gold has been used as a thin coatingon building glazing to improve energy eciencyin the building. Ordinary window glass is almostcompletely transparent to solar radiation (rom theultra violet to the inrared wavelengths). Large glazingareas in buildings can cause signicant heating ointerior rooms and oces and increased loadingon air conditioning installations. Vacuum depositedlms o gold have excellent inrared shieldingcapability and the design o glazing to reduce thisaect has sometimes used thin gold coatings onthe glass. A good example o the use o gold in

architectural glazing is illustrated by the Royal BankPlaza building in Toronto. The building has 14,000windows all coated with pure gold (70,000g in total).The gold reduces heating and ventilation costsinside the building.

There are three signicant drawbacks with thistechnology. Firstly, manuacturing gold-coatedglass is an expensive process (due to the use ovacuum technology rather than precious metalcost). Secondly, modern architectural tastes arenot necessarily drawn to a gold colour. Thirdly thehigh refectance o gold can cause irritating glare insurrounding environments.

Nanomaterials may have the answer; goldnanoparticle coatings can accurately tune the

refective capability o the glazing at a reasonablecost and with the added advantage that a moreappealing range o glazing colours can be obtained(blues and greys).

A team rom the University o Technology, Sydneyhas already demonstrated the principle o thistechnology and recently a U.K. Government-undedconsortium including Pilkington Glass and preciousmetal company Johnson Matthey demonstrateda proo-o-concept principle using gold-basedcoatings. A key requirement is to avoid the vacuum

deposition process which is both costly and slow.Researchers rom the University o Oxord workingwith Pilkington have recently developed a simple,rapid and low-cost approach to large-area depositionusing spray coating.

Solar cells

Over the longer-term, in addition to the solarshielding applications highlighted above, uses ogold nanomaterials in glazing could have utility ingenerating heat - so-called solar harvesting. Takingthis idea a stage urther into the realm o solar cells,early research has shown gold nanomaterials maybe used as an eciency improving additive or arange o solar cell designs; the gold nanoparticlesenhance the optical absorption in the range ovisible light.

Might gold nanoparticles have a role in advanced energy ecient glazing coatings?


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Gold for technology

Gold is well-established as a key material in theelectronics industry. Gold bonding wire, electroplatedcontacts, solder alloys, thick lm pastes andmetallised coatings together use around 300 tonneso gold per year.

As the worlds o electronics and nanotechnologyincreasingly interact in the uture, whether throughthe use o new compounds or dissipating heat asdimensions shrink, or in new applications in plastic

electronics, it seems highly likely the electronicsindustrys use o gold as a critical material willcontinue.

Conductive inks or plastic electronics

Whether or not printable electronics develop into thehuge market that is being predicted as shown above,there will no doubt be an increasing need or metallicinks that, ollowing low temperature sintering, displayexcellent conductivity.

Although nano-inks made rom copper and silverwill orm the bedrock o demand in this market, it isbelieved gold inks will also nd use, either or reasonso material compatibility or because o golds inherent

durability and proven track record o reliability.

The key will be in the development o inks thatcan be applied by some conventional technology,such as ink-jet printing, and which require only lowsintering temperatures to cure (metallise) the inks.Low temperatures are necessary to allow the inks tobe used on the widest possible range o substratesincluding polymers. Both UK company JohnsonMatthey and US-based NanoMasTech have recentlydeveloped such inks which are capable o deliveringexcellent conductivity.

Rapid growth in printed electronics is predicted - durable,conductive gold nanoparticle inks will be vital or someapplications in this market

200

150

100

50

0

1980

1985

1990

1995

2000

2005

2010

2015

2020

2025

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Market volume (Billion $)

Silicon

semiconductors

Printed

semiconductors

Recently, the Department o Electrical Engineeringand Computer Science, University o Caliornia,Berkeley investigated gold nanoparticles asa potential candidate or lead-ree electronicpackaging applications. Its optimised gold inks areable to sinter at temperatures as low as 120C andachieve conductivities o up to 70% o bulk gold. Theinks have been proposed as promising candidates

or next-generation lead-ree solders.

IBM has demonstrated a new nano printingtechnique it believes will lead to breakthroughs inuture computer chips, optics and biosensors. Therecreation o Robert Fludds 17th century drawingo the sun the alchemists symbol or gold wascreated by precisely placing 20,000 gold particles,each about 60 nanometers in diameter [13].

IBM believes the technology could have evenwider application potential. In biomedicine, this

printing process could be applied to generate large

Electronic tracks printed atlow temperature using goldnanoparticle inks

Source: Market orecast SIA, IDTechEx 2006


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arrays o biounctional beads that could be usedor rapid screening or cancer cells or heart attack

markers. The gold nanoparticles can also interactwith light, and with this method optical materials withnew properties could be printed, perhaps or use inoptoelectronic devices.

Touch sensitive screens

Gold nanoparticles have been shown to oerunctional benets to visual display technologies,solving one o the industrys most pressing problems,the increasing shortage o the metal indium. Indiumis required to create touch sensitive screens ordevices such as the iPhone and the electronic-inkdisplays used in E-Book readers. As the area isexperiencing rapid growth, and there are estimatedto be less than teen years supply o indiumavailable, a solution is urgently needed.

Transparent conducting lms based on

nanocomposites o double walled carbon nanotube(DWNT) and gold are being evaluated. Such lmsneed to be highly conductive and transparent, andmany attempts using carbon nanotubes have ailedto match the conductivity o currently used materialssuch as Indium Tin Oxide (ITO). It is now believed thatthe sheet resistance can be reduced signicantlyby reducing carbon nanotube resistance throughthe addition o gold nanoparticles to the lms, thusovercoming bottlenecks in both the use o touchscreens and o carbon nanotubes.

High density data storage

A seemingly never-ending requirement or storage odigital data continues to stimulate the investigationo a broad range o innovative technologies in highdensity data storage.

The use o optical rather than magnetic propertiesor data storage has been o interest or nearly thirtyyears and although CDs and DVDs are part o dailylie, optical storage, while cheap, still cannot copewith storing the huge amounts o data generated byentertainment.

A solution may be on the cards using the same sizeo DVD but vastly increasing its storage capacityrom 8.5 Gb to over 10 Tb (10,000 Gb). Current disksstore data in a series o pits in the surace o thedisc which are read by a laser. A pit is a digital zeroand a non pit is a digital one. By adding a goldnanorod to react to dierent requencies o light,and to allow the light to be polarised adds threeadditional dimensions thus boosting the potentialstorage. The researchers are now working withSamsung Electronics to commercialise thetechnology [14].

Future high density data storage could employ gold nanorods

Robert Fludds 17th century drawing o the sun created by IBMusing 20,000 gold nanoparticles

A similar approach is being applied to non volatilememory storage more commonly reerred to asfash memory o the kind ound in USB sticks andan increasing number o PCs such as the MacBookAir. By using a layer o gold, or a mixture o gold andcobalt, researchers in South Korea have been ableto add more dimensions o data to fash memory.

The more commonly used polycrystalline silicon and


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silicon nitride only allow a single storage level, eithera one or a zero but the gold nanoparticle approach

allows a number o dierent charge levels to bestored on a single memory element, thus allowingar higher storage density to be achieved.

Adding more storage capacity to fash memory can be achievedby using gold nanoparticles

Advanced dyes and pigments

The use o gold nanoparticles to colour objects isnot new; the dye and glaze known as Purple oCassius consists o gold nanoparticles precipitatedonto tin oxide particles. It has been used since 1659to produce red to purple vitreous enamel glazesor use on high value pottery and porcelain. Ournew ound ability to precisely control the size onanoparticles is leading to a range o new opticalapplications, rom ashion to architecture.

Gold nanoparticles have also occasionally beenused to dye textiles, a practice that dates backhundreds o years. However more recently thisunusual use was revitalised by researchers atUniversity o Victoria, New Zealand who have usedgold nanoparticles as novel colourants or highquality wool. This technology is aimed at high valuemarkets, linking the high value and prestige o gold

with premium quality merino wool. Recipients o theInnovator Award rom chemical company Bayer, thisresearch group is pursuing commercialisation o thetechnology and have progressed to a small pilotscale operation, with the production o demonstrationtextiles or customers.

With applications in mind, companies are beginningto oer gold nanoparticles on commercial terms.Swiss company Metalor has recently launched arange o gold nanoparticles or pigment applications.Although the cost o the precious metal will likely

make these niche products, they do display

virtually unlimited stability against UV exposure,good thermal stability and high colouring strength.

Most interestingly, because they can be tuned tohave a unique optical signature, they have potentialapplications in security inks or anti-countereitingmeasures.

The application o thin gold layers to glass andceramic objects using inks to produce a decorativeeect is a technique that, in various orms, has beenused or centuries. Historically gold inks were basedon gold powders dispersed into natural resinousmaterials, which ater ring and burnishing gave thedesired lustrous decorative gold eect.

Inkjet printing using gold nanoparticle-based inks

Today gold nanoparticles may also be used as aprecursor in mixtures designed to produce thesethin, continuous coatings o metallic gold. Recently,Johnson Matthey demonstrated even newer goldnanoparticle ormulations capable o being printed onpaper at room temperature, potentially a technologyor rapid printing in pure gold or luxury greetingcards, gits, certicates or writing manuscripts and

religious texts.


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The opportunities and possibilities identied inthis report are just a subset o the amazing scopeto use gold in the era o nanotechnology. Theseopportunities continue a story that started almosttwo millennia ago. Now, as a readily available andwell understood material, gold nanoparticles areready to be deployed in the battle against disease, inmeeting environmental challenges and to contributeto technologies that improve our lives.

Looking beyond the technologies highlighted here,what might the Gold or Good story be in thelonger-term, perhaps 20 years rom now? Certainlynanotechnology has been the ocus o an everincreasing number o research programs around theworld, with almost $50 billion o government undingbeing pumped into nanotechnologies over the pastdecade and much more destined to ollow. This has,and will continue, to create the basic science thatwill underpin even newer technologies and so theapplications we highlight here are considered to beonly the beginning or gold nanotechnology in theage o innovation. What might we look orward toin the areas o health, environment and technology the themes we have highlighted in this report?

In monitoring our health today only specialised labscan generally perorm the tests required to identiydiseases or pathogens. Tests can take weeks tocomplete and, in many cases, are costly. In theuture, medical diagnostics are likely to be point-o-care type systems using quick and inexpensive kits,perhaps purchased through the local pharmacy. The

stability, sensitivity and reproducibility o manuactureo nanoparticulate gold makes it the ideal material touse or this task in the initial diagnosis o a range oconditions, and has the potential to be one o the keytechnologies deployed in the battle against uturepandemics.

Green or sustainable chemistry, the philosophy oencouraging the design o products and industrialprocesses that reduce or eliminate the use and

generation o hazardous substances, is destined tobecome a key element o societys plans to reduceenvironmental pollution. It will be part o the muchtalked about new cleantech industry. A key parto this philosophy, producing important everydaychemicals rom renewable eedstocks rather thanoil, is still at a very early stage, but current researchindicates that gold nanoparticles are highly eectivecatalysts or the necessary reactions. There isincreasing evidence that gold may one day be akey ingredient in the commercialised processesused by the cleantech industry.

Finally, our thirst or aster, smaller consumertechnology products is straining currentsemiconductor chip design principles. How canwe increase the overall computing power o chipswithout increasing energy consumption? Using light,not electricity, as the basis or uture generationso chips has huge potential. The ability o gold toshine in a dierent way at the nanoscale may oneday lead to its use in building new optical chips or arange o cutting edge technologies.

Where next?

Global government unding o nanotechnologies continues to support the development o gold-based technologies

14000

12000

10000

8000

6000

4000

2000

2004 2005 2006 2007 2008 2009 2010E 2011P 2012P 2013P 2014P 2015P

0

US$ Million

Year

Source: Cientica Ltd


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About the authors

Dr Trevor Keel

Trevor Keel is a project manager in the World Gold Councils

Industrial Sector. He manages a range o research and

marketing projects or the council, and has particular interest in

the use o gold in the elds o medicine/diagnostics, catalysis

and nanotechnology. Previously, Trevor was a principal chemist

at the healthcare company GlaxoSmithKline, and he holds a PhD

in pharmaceutical nanotechnology and a degree in chemistry.

Dr Richard Holliday

Richard Holliday is Director o the World Gold Councils

Industrial Sector, with overall responsibi lity or innovation andcommercialisation o new industrial uses or gold, through

research partnerships with industry stakeholders and early-

stage business ventures. In this regard he recently led World

Gold Councils investment in Nanostellar Inc., the venture capital

unded company that has created the worlds rst automotive

pollution control catalysts based on gold. Co-Editor o the new

book Gold : Science and Applications, Richard is also the

editor o the peer reviewed journal Gold Bulletin.

Dr Tim Harper

Tim Harper is ounder o London based Cientica Ltd, the

worlds leading source o global business intelligence about

nanotechnologies and is one o the worlds oremost experts on

commercialisation o technologies, with experience gained in

both venture capital and the laboratory. Tim has been published

in journals ranging rom Nanotechnology and Nature to

Microscopy and Analysis, in addition to being extensively

quoted in media ranging rom the Financial Times and

Business Week. Tim is also the Founder and ormer Executive

Director o European NanoBusiness Association. He is the

co-author o the Nanotechnology Opportunity Report,

described by NASA as the dening report in the eld o

nanotechnology.

Reerences

1 Report rom US Center or Disease Control and Prevention,

1999:

http://www.cdc.gov/ncidod/eid/vol5no5/pd/mead.pd

2 2009 UN update report on the global AIDS epidemic:

http://data.unaids.org/pub/Report/2009/JC1700_Epi_

Update_2009_en.pd

3 Data obtained rom the prostate cancer oundation website:

http://www.prostatecanceroundation.org/

4 World Gold Council press release:

http://www.gold.org/assets/le/pr_archive/pd/Qun_Huo_

050509_pr.pd5 http://www.worldscibooks.com/chemistry/p450.html

6 A report rom US National Energy Technology Laboratory

Scientists:

http://www.platinummetalsreview.com/dynamic/

article/view/52-3-144-154


http://www.gold.org/assets/le/pr_archive/pd/Belast_

Uni_080609_pr.pd

8 2009 data sheet rom US Center or Disease Control and

Prevention:

http://www.cdc.gov/co/aqs.htm

9 Publication:

de las Heras et al. Energy & Environmental Science, 2009,

2, 206

10 Publication rom Ford Motor Company Scientists:

A Kumaret al, Journal o Power Sources, 2010, 195, 5,

1401


http://www.gold.org/assets/le/pr_archive/pd/ns_wgc_

announcement.pd

12 Johnson Matthey press release:

http://www.platinum.matthey.com/media-room/our-view-on-.-

.-./the-use-o-gold-in-diesel-autocatalysts/

13 http://www.zurich.ibm.com/news/07/nanoprinting.html

14 Publication:

Zijlstra et al. Nature, 2009, 459, 410

BBC article:

http://news.bbc.co.uk/1/hi/sci/tech/8060082.stm


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20

Disclaimers

This report is published by the World Gold Council (WGC), 55 Old BroadStreet, London EC2M 1RX, United Kingdom. Copyright 2009.All rights reserved. This report is the property o WGC and is protected byU.S. and international laws o copyright, trademark and other intellectualproperty laws. This report is provided solely or general inormation andeducational purposes. The inormation in this report is based uponinormation generally available to the public rom sources believed to bereliable. WGC does not undertake to update or advise o changes to theinormation in this report. Expression o opinion are those o the author andare subject to change without notice. The inormation in this report isprovided as an as is basis. WGC makes no express or impliedrepresentation or warranty o any kind concerning the inormation in thisreport, including, without limitation, (i) any representation or warranty omerchantability or tness or a particular purpose or use, or (ii) anyrepresentation or warranty as to accuracy, completeness, reliability ortimeliness. Without limiting any o the oregoing, in no event will WGC or itsaliates be liable or any decision made or action taken in reliance on theinormation in this report and, in any event, WGC and its aliates shall notbe liable or any consequential, special, punitive, incidental, indirect or

similar damages arising rom, related or connected with this report, even inotied o the possibility o such damages.

No part o this report may be copied, reproduced, republished, sold,distributed, transmitted, circulated, modied, displayed or otherwise usedor any purpose whatsoever, including, without limitation, as a basis orpreparing derivative works, without the prior written authorisation o WGC.To request such authorisation, contact [email protected]. In no event mayWGC trademarks, artwork or other proprietary elements in this report bereproduced separately rom the textual content associated with them; useo these may be requested rom [email protected]. This report is not, andshould not be construed as, an oer to buy or sell, or as a solicitation o anoer to buy or sell, gold, any gold related products or any other products,securities or investments. This report does not, and should not be construedas acting to, sponsor, advocate, endorse or promote gold, any gold relatedproducts or any other products, securities or investments.

This report does not purport to make any recommendations or provide anyinvestment or other advice with respect to the purchase, sale or other

disposition o gold, any gold related products or any other products,securities or investments, including, without limitation, any advice to theeect that any gold related transaction is appropriate or any investmentobjective or nancial situation o a prospective investor. A decision to investin gold, any gold related products or any other products, securities orinvestments should not be made in reliance on any o the statements in thisreport. Beore making any investment decision, prospective investorsshould seek advice rom their nancial advisers, take into account theirindividual nancial needs and circumstances and careully consider therisks associated with such investment decision.

Printed on recycled paper with FSC certifcation.


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