Nanobiosensors for Foodborne Threat Detection

Introduction: According to the United States Centers for Disease Control and Prevention (CDC) report, 48 million Americans get sick, 128,000 get hospitalized and 3,000 die each year due to foodborne pathogens. Several attempts have been made to detect those pathogens with high sensitivity and selectivity. The most routinely used methods include Enzyme-Linked ImmunoSorbent Assay (ELISA) and Polymerase Chain Reaction (PCR)-based assays. While ELISA has poor detection limit, PCR techniques are time-consuming and require trained personnel. In this work, we introduce a new ultrasensitive apta-assay based on liposome-mediated amplification of gold nanoparticle aggregation.

Purpose: The purpose of this work is provide an ultrasensitive assay capable of detecting very low levels of a target organism or agent with the naked eye. 

Methods: We have specifically employed this assay using magnetic nanoparticle. In this assay, magnetic nanoparticles labeled with specified DNA receptors known as aptamers are used to capture pathogens in solution. Once the target pathogen is captured, cysteine-loaded liposomes (also labelled with the aptamer) are added to the system and are mixed with plasmonic gold nanoparticles. The liposomes then break down and release cysteine molecules, which in turn causes the aggregation of the gold nanoparticles and a color shift of the solution from red to blue purple.

Results: Our approach showed a detection limit below the zeptomolar level, and the ability to detect a single pathogen with the naked eye. Additionally, this method saves time by overcoming the need of laborious washing steps required by ELISA.

Significance: The assay reported here is a promising alternative for rapid and ultrasensitive detection kits of foodborne pathogens. This assay can also be applied to many other areas of food safety, protection and defense by simply changing the biological receptor (aptamers, antibodies, etc.) in order to select a different target agent.