Perspective Chapter: Gold Nanoparticles Market – A Global Overview and New Challenges in the Post-Pandemic Economy

Abstract

Colloidal gold (AuNP) is a molecule obtained from pure gold (Au), and has several uses in the health, industrial, and chemical sectors. There are several processes to generate it and these methods are perfected over time. However, colloidal gold manufacturers and their customers are dependent on the pure gold market, its disruptions, and fluctuations. This paper first shows that the gold market is currently unstable due to the existing pandemic and geopolitical conflicts. The main gold producers, China, Russia, and Australia, together account for more than a quarter of the world’s gold production, and only a few European countries produce gold in small quantities. Europe is therefore forced to import gold, including colloidal gold. Several innovations related to gold nanoparticles are emerging, notably in the miniaturization of industrial components or in the health sector during the pandemic. The objective of this chapter is therefore to understand the patterns into which these countries must fit to produce these particles and the economic, political, and scientific stakeholders involved in capturing these flows. Through the prism of the gold market, the electronics industry, and the health field, this chapter looks at these issues while putting into perspective the salient facts that could impact this market in the years to come.

1. Introduction

Colloidal gold (AuNP) is a precipitate obtained from pure gold (Au), requiring products, such as gold powder or raw gold. The gold precipitate is called colloidal gold. It is classified as an inorganic nanomaterial. It is notably obtained from a chloride solution (sodium chloride, tin dichloride, etc.). There are three main manufacturing methods: Turkevich [1], Brust [2], and Perrault & Chan [3]. The color of colloidal gold varies between red and purple. It depends on the size and shape of the powder produced, whose particle diameter generally varies between 1 nm and 100 nm [4].

Turkevich’s fabrication method, reviewed by Frens in the 1970s, consists of a first step of positioning on a hot plate a gold chloride, that is, gold in ionic form in an aqueous solution. This solution is colorless currently. By adding a small amount of sodium citrate, the gold is reduced and metallic gold nanoparticles of 15 nm in diameter appear suspended in the water. The precipitate then takes on a ruby-red color, attesting to the presence of the gold nanoparticles [5].

Brust’s method, developed in 1994, makes it possible to prepare colloidal solutions of gold in organic solvents immiscible with water. The average diameter of the nanoparticles obtained is between 1 nm and 5 nm [2]. The objective of this synthesis is to react chloroauric acid with sodium tetrahydruroborate, which acts as a reducing agent, in the presence of tetraoctylammonium bromide, which acts as a stabilizing agent and phase transfer catalyst. It is then necessary to wait about 2 weeks for the nanoparticles to aggregate and precipitate [2].

In 2009, Perrault and Chan proposed a method for making colloidal gold in the 50–200 nm diameter range using hydroquinone as a reductant of chloroauric acid in an aqueous solution containing smaller gold nanoparticles. The use of citrate is then used to control the growth of the nanoparticles [3].

The use of colloidal gold is ancient. In ancient times, it was used as a dye, especially for porcelain. Today, it has three main uses: health, electronics, and chemistry field [6]. There are also some secondary uses in cosmetics (because colloidal gold has antiaging properties), photometry, etc. In the field of health, gold, as a trace element, is a universal natural antibacterial [7] and has anti-inflammatory properties. In the field of electronics, colloidal gold is used for its conductivity [8]. It is used in the manufacture of electronic components. In chemistry, as a catalyst, colloidal gold is used as a marker in immunoassays, imaging, and resonance sensors [9].

The purpose of this chapter is to provide an overview of the use of colloidal gold through the prism of its raw material, pure gold. First, the aim is to describe the gold market situation contextually, and to analyze its production and its use on a global scale. Then, we will detail the typologies and behaviors of the gold market in all its forms before focusing on the use of gold nanoparticle manufacturing. We will then analyze the market trends of products containing these molecules before demonstrating the interest in colloidal gold against the COVID-19 pandemic. Finally, we will conclude this chapter with a prospective conclusion focusing on the challenges that could affect this market in the coming years.

2. Context

As the methods of manufacturing colloidal gold are multiple and well known, the main difficulty is not to generate this molecule, but to obtain pure gold. It is therefore appropriate to focus on the trade of this rare material. There are 45 territories with active gold mines, with production led by China, Russia, and Australia, expected to reach more than 3500 tons in 2021 (Figure 1) [10].

Figure 1.

Major gold-producing countries in the world from 2010 to 2021 [10].

Indeed, gold mining is a global industry, present on all continents except Antarctica [10]. It is extracted from mines of widely varying sizes and types around the world. Gold mines and mining operations are becoming increasingly geographically diverse, a far cry from the concentrated supply of some 50 years ago when most of the world’s gold came from South Africa [11]. Overall mine production levels have increased significantly since 2008, although significant discoveries are increasingly rare.

Gold is beyond its image as a shiny precious metal. It is a rare material with a variety of uses (seeFigure 2). In total 52% of the gold produced on average between 2008 and 2017 was transformed into jewelry or 2.23 tons per year. In total 27% of the quantity mined was transformed into ingots and coins, 9% is used in the technology industry, 8% is used as a reserve for central banks, and 3% is invested in the stock market via ETFs [10]. Gold is also used in the medical sector. Some drugs contain it as well as some treatments against specific diseases, such as rheumatoid arthritis, Crohn’s disease, psoriatic arthritis or cancer (Figures 3 and 4) [17].

Figure 2.

Gold production and use cycles in 2021 (MOBIS based on several World Gold Council data 2022 [12, 13, 14, 15, 16]).

Figure 3.

Evolution of gold production in the world between 2010 and 2021.

Figure 4.

Segmentation of the gold nanoparticle market in 2021 [18].

In terms of gold nanoparticles, it should first be noted that the annual demand amounted to 1600 tons in 2020. The gold nanoparticle market can be segmented as follows [18]:

• Electronics;

• Health Care;

• Chemicals;

• Other.

We observe that the growing application of nanotechnology in medical diagnostics, increasing R&D in gold nanoparticle technology, and growing demand in the electronics and development sector for specific applications are the major drivers of this market. However, stringent regulations and standards for nanomaterials may hamper the market growth [18].

Finally, the key players in the global gold nanoparticle market, after analyzing their capacity, market share, and latest developments, such as capacity expansions, plant closures, and mergers & acquisitions, are identified as follows [18]:

• Cytodiagnostics Inc. (Canada);

• Goldsol Inc. (Netherlands);

• BBI Solutions OEM Limited (United Kingdom);

• NanoHybrids, Inc. (USA);

• Nanopartz Inc. (USA);

• Nanosphere Inc. (USA);

3. The pure gold market: a pillar for the manufacture of colloidal gold

The Observatory of Economic Complexity (O.E.C.) data visualization informs about the gold trade market. We observe that since the price of gold fluctuates, its variation has a strong impact on the value of trade. It would be more interesting to visualize the variations in tons, and not in dollars. To achieve this, it is possible to use the variation in the price of gold between 1996 and 2019 (Figure 5). The value used is the average of all monthly closing prices. The years 1995 and 2020 are excluded for lack of value.

Figure 5.

Evolution of the average annual closing price of gold in current dollars per kilogram between 1996 and 2019.

In fact, by cross-referencing O.E.C. data with average gold prices, it is possible to estimate the annual tonnage of gold sales between 1996 and 2019 (Figures 6 and 7). We observe that gold powder traded is decreasing between 1996 and 2019, while that of gold blocks has reached a kind of ceiling. Moreover, price fluctuation is not a relevant indicator for studying the movement of gold (Figures 8 and 9).

Figure 6.

Evolution of estimated tons of gold traded for gold blocks (710812) between 1996 and 2019.

Figure 7.

Evolution of estimated tons of gold traded for gold powder (710811) between 1996 and 2019.

Figure 8.

Evolution of traded values for gold blocks (710812) in current dollars between 1995 and 2019.

Figure 9.

Change in traded values for gold powder (710811) in current dollars between 1996 and 2019.

A closer analysis of the O.E.C. data tells us that the gold trade is not limited to the products of mining, but also the gold stock in circulation. Regarding the fact that gold stocks are mainly held by central banks, in reality, there is little gold in circulation, apart from the gold produced, but it is difficult to estimate. Moreover, this gold is impure, therefore, it requires treatment to be transformed into colloidal gold. The list of territories trading gold (in powder or blocks) is abundant (191 territories). Thus, it is more interesting to observe the exchanges between the producers and the rest of the world. Producers export little gold powder compared to gold blocks. Few producers import gold: only South Africa, Australia, Canada, China, the United States, and Turkey. Gold is likely to be a backup resource for producers, as there are still few exports. It is therefore safe to assume that the majority of gold remains in the country.

It is important to note that the price of gold is very fluctuating and volatile due to several factors. The price of gold is estimated twice a day by the LBMA, whose administrator is the ICE Benchmark Administration Ltd. (IBA), which serves as the main global reference since 2015 [19]. Each price definition is based on a comparison of supply and demand. Thus, high demand and a low supply will logically push the LBMA to revise the price of gold upwards, while the opposite case leads to a decrease in the cost of this commodity.

Over the past 25 years, two distinct periods have emerged in terms of gold prices (Figure 5). Between 1995 and 2001, gold prices were relatively stable at around $300 to $400 per ounce. In the early 2000s, the U.S. economy was challenged by the bursting of the “dot-com bubble,” which led to some huge financial difficulties among powerful companies, and the World Trade Center attacks. That event contributes to the rise in the value of gold, which is highly prized in times of crisis because, it is a safe haven par excellence [20]. Gold is the main asset that every investor, every saver, and every central bank seeks when the economy and finance falter or prediction some economic shocks. All this parameter takes is one or two detonators in an explosive context to trigger a gold rush. This is what happened in the early 2000s, the rise of the gold price was inevitable. Thus, between 2000 and 2006, the price of an ounce of gold doubled.

While prices rose sharply in the early 2000s, the end of the decade marked an economic turnaround that sent the value of gold soaring. With the subprime crisis affecting markets around the world since 2008, investors massively bet on the gold market as a safe haven. The price of the yellow metal was fueled by this, surpassing the $1000 per ounce mark for the first time in history in September 2009. The rise continued until July 2011 when the ounce of gold exceeded $1800. This rise after 2009 is explained by the beginning of the economic recovery: growth and employment are moving forward again, but with their inflationary corollary (loss of value of the dollar). This increase in the price of gold has several origins: the decline of the dollar, the currency in which gold is denominated, very strong demand for gold from countries with growing middle classes, and insufficient supply as stocks are depleted.

From 2012 onwards, the rise in the gold price reversed and begins to decline. There are no longer any major geopolitical conflicts, the dollar has not collapsed, the United States has not defaulted on its debt, the eurozone has not exploded and the stock markets have recovered. From 2012 to 2019, however, prices remain very high, with the value of an ounce fluctuating between about $1000 and $1300. In 2019, the trade war between the U.S. and China and the approaching agreement between the UK and the EU on Brexit are reigniting uncertainty in the markets and pushing prices back up.

The COVID-19 pandemic crisis has accentuated this trend with an ounce passing the sympathetic $2000 mark in July 2020. Since the outbreak of the SARS-CoV-2 virus, the ounce of gold has never fallen below $1700, and the Ukrainian-Russian conflict that began in February 2022 looks set to create a significant political instability in the coming years, leading to a supply crisis in raw materials helping to stabilize a high gold price for years to come.

The main demand for foreign gold purchases by countries around the world comes from central banks. Indeed, by 2021, with over 35,000 tons of gold held in their vaults [21], central banks, and international financial organizations are major players in the gold market. The amount of gold held by central banks corresponds to almost one-fifth of the gold ever produced. Central banks buy gold bullion and with prices, the data fluctuates according to global economic conditions (Figures 6 and 8).

During the 1990s, central banks were net sellers of gold, a behavior that became more pronounced in the late 1990s. From 1999 to 2008, central banks “sold 3884 tons, that is, an annual sales volume of nearly 400 tons, which represents a tonnage greater than the annual production of South Africa, the world’s leading producer at the time. Until 2009, central banks were the second-largest source of gold supply after mining. The main declines in central bank gold stocks during this period were observed in France (- 390 tons), Switzerland (- 250 tons), Spain (- 176 tons), and the Netherlands (- 82 tons)” [22].

Central banks changed their tune in 2008 with the financial crisis. Since then, their holdings of yellow metal have increased by nearly 5800 tons, or an average of 415 tons per year. This means that about 11% of the world’s mining production ends up in the coffers of these institutions since this time [23]. This buying behavior can be observed particularly among certain central banks in emerging markets, whose demand for gold has increased considerably, favoring a gradual shift in the gold market toward Asia.

Furthermore, gold is strongly correlated to real interest rate levels, that is, the level of interest rates minus the rate of inflation (or more precisely inflation expectations). The correlation is so strong that it is graphically obvious (Figure 10). The lower the policy rates, the greater the demand for gold by central banks and the higher the price of gold. This is why we observe graphically a correlation between the volume of gold traded and the value of gold traded in dollars between 1995 and 2019 (Figures 6 and 8).

Figure 10.

Evolution of the price of an ounce of gold and the interest rates of the American central bank between 2009 and 2015.

Gold powder has a different use than bullion. Gold powder refers to fine particles of gold, natural or artificially produced. Like the gold leaf, gold in powder form is used for decoration: gilding of jewelry or glassware, paint, makeup, but also food or skin care. The gold powder was also used as currency, particularly in West Africa during the pre-colonial West African empires [24].

The main importers of gold powder are the United Arab Emirates (16 tons), Belgium (10 tons), and Niger (3 tons). The three largest exporters are the Philippines (17 tons), Nigeria (16 tons), and the United States (2 tons) [25]. Since gold powder requires a lot of work upstream of production and is used in smaller proportions, exchanges of this type are rarer than for raw gold or bars. Indeed, the share of gold powder trade in global trade is negligible (40 tons in 2021 out of the 4500 traded) [25]. Furthermore, there is no direct correlation between the demand for gold bullion and gold powder. The comparison of the curves in Figures 6 and 8 with Figures 7 and 9 confirms this trend. However, data series are available that allow for economic trend analysis of the gold powder economy.

In terms of quantity traded, unlike gold bars, gold powder had significantly higher volumes in the 1990s than in 2000 and 2010 (see Figure 7). This is due to the rise of gold-producing countries, such as China, which have taken advantage of their mined resources to produce gold-based manufactured goods, such as jewelry, and then export them. Today, there is a correlation between the position of the gold-producing countries and the gold jewelry exporting countries, which induces that most of the big jewelry producers are not need to import gold for their production. Most gold importing countries buy unmanufactured gold to process it themselves according to the products to be manufactured. However, some gold jewelry-producing countries remain dependent on gold powder imports, including Australia, India, the United Arab Emirates, and Italy (Figure 11) [26].

Figure 11.

Share of gold powder imports by country in total world imports by 2020 [26].

It should be added that the COVID-19 crisis has driven up trade in terms of gold powder. In fact, in 2019, the annual value of gold powder traded was about 10 tons compared to 40 tons in 2021 [25]. This is due to the use of gold powder processed into colloidal gold in antigenic tests for the disease (Part 7).

After having discussed the evolution of the price of gold, the exchange of gold blocks, and gold powder, we will now look at the exchange of gold of all forms according to the countries. Figures 12–15 are intended to better focus on the major importing and exporting countries of gold in all its forms in the world since 1995.

Figure 12.

Evolution of gold powder exports between 1996 and 2019 (tons).

Figure 13.

Changes in gold powder imports between 1996 and 2019 (tons).

Figure 14.

Changes in gold block exports between 1996 and 2019 (tons).

Figure 15.

Changes in gold block imports between 1996 and 2019 (tons).

In 2021, the top five importers of gold are Switzerland (2208 tons), India (1068 tons), the United Kingdom (927 tons), China (821 tons), and Hong Kong (523 tons) [25]. If the fact of seeing four countries producing little or no gold at the top of this ranking is not surprising, the case of China may raise questions. First of all, it should be noted that China is only sixth in the world in terms of gold reserves, with nearly 2000 tons, four times less than the United States. The reason why the Chinese are amassing as much gold as possible is that the Chinese government hopes that its yuan currency can become an international reference currency [27]. This trend has been confirmed since the early 2010s with an explosion in Chinese gold imports (Figure 15).

Other gold-producing countries also import large quantities of gold to regulate their economies, such as Australia, the USA, and Canada (see Figure 15). Countries without gold production but with strong economies import gold in large quantities to regulate their economies, manufacture gold-based products, or for gold refining. This is the case of Switzerland, the eighth country in the world in terms of gold reserves, producer of gold jewelry, and first world importer and exporter, with four out of five of the world’s largest gold refineries located on its territory.

In 2021, the top five exporters of gold are Switzerland (1500 tons), the United Kingdom (716 tons), Hong Kong (538 tons), United Arab Emirates (487 tons), and the USA (481 tons) [25]. As we have said, Switzerland occupies this position because it is the hub of global gold refining. Expect the USA, all these countries are not among the main gold producers.

It may also seem surprising that of these five countries, only one is a major gold-producing country. The observation we can make from the figures is that the major gold-producing countries keep most of their products in their stocks. The need to hold on to one’s gold can be seen immediately during periods of crisis, particularly between 2008 and 2012, when all producing countries exported less gold than in previous and subsequent years to limit risk aversion (Figure 14).

Smaller countries, on the other hand, will export a larger share of their production to benefit in the short term. This is the case, for example, of Peru or African countries that make significant profits each year by selling their stocks of gold produced rather than keeping it in the central bank or by exporting manufactured goods (see Figure 14). These resources are vital for these countries. For example, almost 10% of Peru’s GDP and 60% of exports emanated from mining in 2018 (Estado [28]).

All these data are fundamental to understanding the colloidal gold market. According to (Inkwood [29]) 13 territories are producing colloidal gold: the United States, Canada, Germany, the United Kingdom, France, Italy, Spain, Russia, China, India, Japan, South Korea, and Australia. It is therefore manufactured in the main industrial countries. However, in this list, only the United States, Canada, Russia, China, and Australia have gold mines. The rest of the territories on the list are totally dependent on their pure gold stocks, on the one hand, and their pure gold imports on the other.

Among the biggest dependents is Europe, where only Bulgaria and Finland produce gold. The main shortcoming of colloidal gold production is the scarcity of raw material on the planet. The production of the precipitate requires only a little pure gold, but it must be available. The value of gold prices remains very high, but there are few exporters among the producing territories.

4. Pandemic and gold demand market in the world

Before discussing the various uses of gold nanoparticles and the inherent markets in more detail, it is first necessary to analyze the behavior of the pure gold market during this period to assess possible correlations with colloidal gold. From the beginning of the pandemic in March 2020 until mid-2021, gold demand reached levels as low as in 2008 during the financial crisis [30]. Between 2019 and 2020, global gold demand declined 14% year-over-year, according to the World Gold Council. The organization says demand for gold jewelry fell 34% from the previous year, reaching a historic low [31]. At the industry level, between 2019 and 2020, the decline in gold demand has been estimated at around 7%.

At the end of 2021, a rebound in global gold demand was noted (+10%) compared to 2020 [10]. Demand for gold jewelry jumped by 67% over the period and represents more than half of the global demand for gold. At the industry level, over this period, an increase in gold demand is measured at around 9%. If a rebound in demand is noted, it remains 8% lower than the pre-pandemic level (Figure 16) [10].

Figure 16.

Evolution of the world’s gold demand between 2010 and 2021.

At the beginning of the pandemic, the price of gold rose sharply. By the end of the first half of 2020, the price of an ounce of gold surpassed the $2000 mark [32] a peak not seen since the beginning of the century. This price increase is explained by a strong rebound in demand at the end of the various confinements imposed by most countries in the world. The explosion in demand has led to a logical rise in prices, especially as a sharp increase in the cost of maritime freight has been observed. This increase in the price of transport was therefore logically reflected in the routing of raw materials [33].

Moreover, as gold is considered a haven, the number of investments has increased significantly (+40% compared to 2019) during this period of economic crisis and the price of this metal on the stock market has soared [31]. This trend is confirmed by the figures for the year 2021, where the World Gold Council announces that the demand from central banks has increased by 82% compared to 2020, reaching the number of 35,600 tons of gold stored by them, the highest quantity in over 30 years [10].

5. Gold nanoparticles in manufactured products

Gold and gold-based alloys are materials used extensively in industry, particularly in electronics and semiconductors. Between 200 and 300 tons of gold are put to use each year within these industries [34]. This important use is linked to its high resistance to corrosion, its good electrical and thermal conductivity, its simple use, its ability to create alloys, and its aptitude for soldering. Gold is mainly used to make contacts, connectors, films for electronic components, and even inks [35].

A small amount of gold is present in almost every electronic device we use daily. These include smartphones, computers, touchscreen tablets, televisions, GPS devices, and the like. While the amount of gold used per device is minute when you consider that nearly a billion smartphones are produced each year, and most of them include gold, the large amount of metal needed by the electronics industry is justified. With the profusion of such devices on the market, this amount is expected to increase in the coming years.

Gold nanoparticles have a more specific use: the miniaturization of components. Manufacturers are beginning to take advantage of the minute size of gold nanoparticles to serve as electronic connectors, particularly via metallic “nanotubes” [35], which are smaller, lighter, and more flexible than conventional metal tubes. The assembly of gold nanoparticles is therefore a technology of the future; as electronic components are constantly being reduced. The technique is already used by major manufacturers, such as Sony, Huawei, and Samsung [36].

This ultra-miniaturization of components using nanotechnology has a name: molecular electronics [37]. This has developed rapidly in recent years with the development of techniques needed to measure the electronic properties of molecules, whether single entities or small ensembles, in a variety of two- and three-electrode test platforms [38]. These testbed junctions have revealed the critical roles played not only by the chemical structure of the molecular component backbone but also by the nature of the contact between the electrode and the molecule [38].

Based on the success of molecular electronics feature measurements in test platforms, the next major challenge to be addressed before molecular electronics can be considered a truly viable and scalable technology is the construction of robust and reliable metal-molecule contacts [38]. A wide variety of molecular functional groups have been tested as contact groups for various substrates (primarily gold), including thiols, amines, carboxylic acids, dithiocarboxylic acids, esters, pyridyl, cyano, isocyano, isothiocyanato, nitro, methylselenide, methylthiol, dimethylphosphine, trimethylsilane, fullerenes, etc. [38].

The second major challenge in molecular electronics is the fabrication of the top contact electrode in metal-organic monolayer-metal devices based on a two-terminal vice. Metallization of organic monolayers has been studied for more than 30 years and, like metal-molecule contact, is still not a well-solved problem. A wide variety of techniques for depositing the top metal electrode have been described in the literature, including direct and indirect evaporation, the use of liquid metals, flip-chip lamination, electrodeposition, and surface diffusion-mediated deposition [38].

6. Trends in gold-containing electronics markets during the pandemic

The COVID-19 pandemic has led to a slowdown in the production chains of industries in countries around the world. Indeed, within OECD countries, production decreased by about 7% between 2019 and 2020. By the end of 2021, production levels had returned to pre-pandemic levels [39]. These difficult months have also had a strong impact on household consumption, with a 6.7% fall in volume in France in 2020 and a 5.2% rebound in 2021 [40].

In the electronics industry, the COVID-19 pandemic has led to unprecedented shortages. This crisis primarily concerns semiconductors, electronic chips necessary for the transmission of information, as well as their processing and storage. Indeed, since the beginning of the year 2020, semiconductor manufacturers are unable to meet the demand [41]. These components are essential in the manufacture of modern everyday goods, such as cars, electronic devices, bank cards, and video games.

Gold is a material used in the manufacture of certain semiconductors [42]. Semiconductor suppliers rely on gold and platinum to make robust electronic components through the alloying of several materials. These precious metals are chosen because they offer the high electrical conductivity and corrosion resistance necessary for superior performance. They also facilitate ohmic contact with the compound semiconductors [43].

With gold concentrations reaching 300–350 g/t for cell phones and 200–250 g/t for printed circuit boards [44] we can say that the amount of gold used per device is extremely low (25 milligrams on average per device). However, with 1.5 billion smartphones sold in 2021 and nearly 6 billion connected devices in operation worldwide, the number of precious metals and gold consumed is high. Indeed, according to these figures, if each electronic device contains 25 mg of gold on average, the total mass of gold present in these objects amounts to 1500 tons. For the simple smartphones sold in 2021, about 340 tons of gold are present (average established according to our estimation).

During the pandemic period, some gold-containing electronics markets slowed down sharply. Between 2019 and 2020, the smartphone market fell by 10.5%, and the new car market by 17%. However, this trend must be qualified. Despite declining production, the demand for electronic products has increased overall. The TV market grew by 1.1% (while projections called for an 8.7% decline in early 2020), the touch tablet market jumped by 13.6%, and the video game market by over 10%.

This discrepancy between a global increase in demand, boosted by the explosion of online trade, and a sharp slowdown in production has therefore led to this crisis in the electronics sector. As far as gold is concerned, it is therefore logical to come to this conclusion: industrialists’ need for gold has decreased as a result of the slowdown in production, but in the various markets, demand has increased. Less gold was used in industrial production, but more gold was consumed in the electronics markets. The year 2021 and the beginning of 2022 have confirmed this trend, with demand still strong in the markets and difficulties still present from a production perspective. Semiconductor production demand is expected to increase significantly in the coming years as chips are increasingly integrated into the critical technologies of today and tomorrow.

Consumers are therefore turning more and more to the refurbished electronics market. In France, in 2021, the refurbished smartphone sector has seen a 15% increase, with most customers justifying this choice by the attractive prices charged, the shortages encountered as well as the ecological dimension linked to the reuse of resources, including gold.

7. Use of colloidal gold during the COVID-19 pandemic

As mentioned, the gold and gold nanoparticles sector is not only about electronics but also about health. One of the major challenges of the COVID-19 pandemic was the detection and traceability of people carrying the virus, which was possible through the use of screening tests. Several types of tests were mainly used: antigenic, PCR, and self-tests. The objective of RT-PCR tests is to make a reagent react with the genetic code of the virus (RNA). The antigenic test focuses on the structural proteins of the virus, the spike protein (S), and the nucleocapsid protein (N) [45].

Several types of molecules can be used to detect SARS-CoV-2. The antigenic test procedure consists of depositing a nasopharyngeal swab dipped in a reactive fluid onto a nitrocellulose membrane [46]. The sample is added to a starting zone containing a conjugate detection reagent, which consists of a specific antibody to one of the epitopes of the antigen to be detected and a detection reagent [47]. In principle, any colored particle can be used as a detection reagent, but latex (blue color) or gold nanoparticles (red color) are the most commonly used [48]. This principle is called immunochromatography.

Of the 227 tests approved by the EU (as of July 22, 2022), 44 work with colloidal gold, that is, nearly 20% [49]. During the year 2021, France recorded 168,215,000 tests performed, of which 48.8% were antigenic (82 million tests). Although there are no official statistics on the type of tests performed during the pandemic period, given the large number of samples taken, colloidal gold played a major role in detecting positive cases.

In addition, several studies have shown that gold nanoparticles can have an antiviral function and thus act on SARS-CoV-2 [50]. The scientists relied on other experiments carried out in the past, notably in the context of the treatment of the AIDS virus (HIV) and influenza (flu). Indeed, gold nanoparticles can inhibit the cell fusion of HIV-1 [51]. As for influenza, experiments have shown that gold nanoparticles have an attenuating impact on the infectivity of Influenza-A [52].

Unlike some of the molecules tested during the pandemic, gold nanoparticles have several advantages: they do not induce drug-resistant viral strains and have excellent virucidal properties [53]. However, treatments against SARS-CoV-2 are rarely approved by the authorities. Indeed, only eight treatments have been approved by the European Medicines Agency, and none of them contain gold nanoparticles. In the United States, auranofin, a treatment already on the market and approved by the FDA to relieve rheumatoid arthritis, is one avenue of research scientists are pursuing that could lead to a treatment for SARS-CoV-2 [54].

Colloidal gold and its gold nanoparticles are primarily used for virus detection due to their role in the operation of immunochromatography. While interesting research is being conducted on the antiviral potential of gold on the COVID-19 virus, it is not yet on the market as a treatment or vaccine.

8. Conclusion

To conclude this chapter, we have seen that the gold market is crucial to the global economy. With its multiple applications and its high value due to its scarcity, gold is a material whose production and trade directly impact the currency, stock market, jewelry, and industrial sectors.

The COVID-19 crisis has not spared the gold market, which has seen a significant increase in prices and an overall decrease in demand. While prices have declined in 2021 as most jurisdictions approach a return to normalcy, the gold market is still feeling the impact in 2022. Prices are rising again and reaching very high levels due to the strong demand for gold-based exchange trade funds (ETFs) and the Russian-Ukrainian conflict. In fact, at the beginning of the war, players in the gold market, which is used as a haven in unstable times, saw demand increase by 34%.

At the end of the COVID-19 crisis and at the beginning of a geopolitical conflict in Europe in February 2022, the gold market is still unstable. The recent increase in interest rates by central banks to fight inflation is pushing players to invest in long-term assets, such as bonds, which is beginning to reduce demand for gold and thus its price. However, the instability of the market is likely to last because of the war in Ukraine, as the conflict has completely disrupted the production channels for raw materials. Prices are therefore nervous and unusually reactive as far as gold is concerned.

In the industry, the semiconductor shortage is here to stay. According to the largest manufacturers, mainly located in Asia, production levels should return to equilibrium at least by the beginning of 2024. In gold, industrial demand in the first quarter of 2022 remained stable. The technology sector has had a promising start to the year: demand is the highest recorded for the first quarter since 2018, thanks to a modest increase in the gold used in electronics.

The issue that is now agitating gold market players and authorities is Russian gold. As we have seen, Russia is one of the world’s three largest producers, and the economic sanctions applied call for an outright ban on Russian gold imports, the country’s second-largest source of profit after energy. The effect of this measure is to raise gold prices and deprive those who apply it of a preferred gold supplier. The prospect for gold importing countries is to readjust their supply strategies and find gold at a competitive price.

Finally, colloidal gold, which requires little gold and has disruptive functionalities to be exploited in the years to come, particularly in industry and health, should see its market continue to expand despite the current economic shocks. The need for gold nanoparticles during the COVID-19 crisis demonstrated the interest and potential of this technology for scientists and health authorities. As research continues to evolve, more profits could be made from the use of colloidal gold in the years to come, increasing the size of its market and the number of players driving its supply and demand.

Acknowledgments

The authors would like to thank 5D, company (France) for providing access to some informations on the godlnanoparticles market as well as for reviewing this work before submission.