**1. Introduction**

The fastest growing and expanding agricultural sectors worldwide are the livestock, poultry and aquaculture industries. These industries need to grow and expand fast to sustain the needs of the growing population. However, this massive growth is in constant threat of outbreak of different infectious and/or zoonotic diseases [1]. Furthermore, the globalization of animal trade can further contribute to the spread of diseases such as spread of *Trypanosoma evansi* from the tse tse belt of Africa toward the rest of the world [2]. Thus, unforeseen entry of disease in a country or area may lead to rapid undetected spread of disease with late diagnosis. To prevent or slow down spread of animal diseases, the World Organization for Animal Health (OIE)

prescribed the use of rapid, accurate and highly sensitive identification and detection of these different infectious agents [1].

The application of molecular tool such as Polymerase Chain Reaction (PCR) has become one of the most important routine diagnostic procedure in the laboratory [3]. Furthermore, the development of Loop-mediated isothermal amplification (LAMP) by Japanese researchers further advanced disease diagnostics with its simplicity and cost-effectiveness [4]. However, even with the new PCR or LAMP techniques developed to detect different animal diseases, still, most of animal diseases are not properly diagnosed. Thus, development of methods and techniques that are more sensitive, specific, cost-effective, and can be used under field conditions are of paramount importance.

Noble metals are metals that have outstanding resistance to corrosion and oxidation at elevated temperature. These metals have a long and rich history and was reported to be used as early as the First Egyptian Dynasty. Noble metals include the metals of groups VIIb, VIII and 1b of the second and third transition series of the periodic table such as rhodium (Rh), ruthenium (Ru), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt) and gold (Au) [5]. These metals belong to a group of elements with wide variety of use and applications in fields of aerospace, electronics and most significantly, health [6].

Nanotechnology is an emerging science and is the study of matter with one or more dimensions in between 1 to 100 nm. The combination of nanoscience and biotechnology has created a new growing field of research in the form of nanobiotechnology with massive opportunities [5] to further improve healthcare, medical treatments, therapeutics and biomedical [7] uses such as radiotherapy enhancers [8–10], drug and gene delivery vehicles, and highly specific and sensitive diagnostic assays [11, 12].

Among all noble metals, gold (Au) and silver (Ag) are the most extensively studied due to the well-established synthesis routes, their relatively higher content in the earth's crust and better safety profile. Furthermore, gold and silver nanoparticles demonstrated the most fascinating properties for biosensing. Gold nanoparticles (AuNPs), commonly known as colloidal gold or gold colloids, are the most stable metal nanoparticle. AuNPs present distinctive characteristics like size-related optical, electronic and magnetic properties, individual particle behavior and specially, compatibility with biomolecules [10, 11]. These characteristics of AuNPs attracted researchers from the field of human and animal medicine to apply these properties in a point-of-care or field diagnosis of various infectious diseases. In 1996, it was originally reported the capability of nucleotide functionalized AuNP can detect DNA colorimetrically [11, 13]. Moreover, AuNPs had been used for the detection of pathogenic DNA, single nucleotide polymorphisms and sequence discrimination [11, 14]. Researchers used AuNP in the development of numerous disease detection or screening platforms or techniques. This made gold as the most used noble metal in the field of point-of-care or field diagnostics [15].

AuNPs remain the most studied noble metal for disease diagnostics due to its biocompatibility and chemical stability [10, 16–18]. However, silver nanoparticles (AgNPs) are reported to habitually result in better sensitivity compared to AuNPs [18, 19]. Furthermore, Ag has higher thermal and electrical conduciveness, and more efficient to transfer electron than gold with shaper extinction band and AgNPs are more stable in water and air. Thus, the use of Ag has also attracted researchers to be used in drug delivery, environmental, electronics, antimicrobial agents and in diagnostics. Furthermore, AgNPs have been prominent in the field of biosensor and imaging [15].

#### *Application of Noble Metals in the Advances in Animal Disease Diagnostics DOI: http://dx.doi.org/10.5772/intechopen.99162*

Aside from Au and Ag, platinum (Pt) is another noble metal that has been noteworthy scientific tool explored by researchers in the field of biotechnology, nanomedicine and pharmacology [20].

In this book chapter, the different routes of synthesis and application of noble metal nanoparticles were discussed in order to give an overview on the recent advances and/or point-of-care animal disease diagnostics using these noble metals.
