Gold Nanoparticle Biosensors

Executive Summary

Harmful microbes are present in a variety of sources including water, food, plants, and through human-to-human transmission. The ability to detect them rapidly at low cost is important to protecting the health and safety of humans and animals and the security of food chains. MSU researchers have developed novel gold (Au) nanoparticle biosensors for rapid sensing of bacteria, proteins, viruses in a variety of media. The biosensors can be used in a variety of application settings without the need for pre-purification, lengthy culturing, and amplification. The particles can be functionalized to bind to targets of interest (cells, proteins, DNA, or RNA) and easily detected by electronic, optical and molecular recognition techniques.

Description of Technology

This technology covers a suite of inventions relating to gold (Au) nanoparticles (a.k.a. Au NP) and a one pot method of making them and their use. The nanoparticles are made at neutral or low pH in the presence of a carbohydrate such as an oligosaccharide or dextrin. The process leads to controlled particle growth, uniform and small particles ranging from 8 to 50 nm. The nanoparticles are functionalized with thiol and receptors, such as proteins, antibodies, and oligonucleotide probes. In some cases, the core of the particle may contain a magnetic material. Upon mixing with the media containing the target analyte, the functionalized Au NP’s bind to target analytes. Magnetic Au NP’s – bound to target analytes may be selectively separated with a magnet to concentrate them. Non magnetic Au NP’s – bound to target analytes can also be concentrated in the same manner, by the addition of additional functionalized magnetic NP’s. The concentrated Au NP – target analyte complex can be conveniently detected by electronic, optical or molecular recognition techniques.

The technique can identify the presence of bacteria, proteins and virus as separate types of microbes or can identify specific species if DNA probes are used such as Mycobacterium tuberculosis or Escherichia coli.

Benefits

Simple method of detecting the presence of bacteria, proteins and viruses present in a sample
Can be used on multiple media such as sputum, water, food matrixes, urine, blood
Eliminates pre-enrichment, purification, pre-treatment steps
Rapid detection. Improves diagnostic speed (less than one hour after DNA extraction of the sample)
Inexpensive test method

Applications