Point-of-use nanosensor for detection of citrus greening disease (Huanglongbing) Extramural Project uri icon

Overview

objective

  • The overall goal of the proposed research is to develop, characterize, test and validate a point-of-use (POU)/field-deployable immunosensor for highly sensitive and selective, rapid, facile, cost-effective and quantitative detection of HLB using Ca. Liberibacter secreted proteins as biomarkers. The sensor is based on immunomagnetic capture of the HLB biomarker from infected citrus trees by magnetic core and gold shell nanoparticles that are functionalized by anti-biomarker antibodies followed by analysis of the captured antigens by a novel graphene nanogap sensor. The specific aims of the project are: Generating high affinity antibodies against secreted proteins of Ca. Liberibacter and select one secreted protein as the biomarker for HLB. Fabricating a pair of graphene electrodes separated by nanometer gap distance. Performing site specific immobilization of one antibody against the selected HLB biomarker in the nanogap between the graphene electrodes. Synthesizing magnetic core-gold shell nanoparticles and functionalizing them with second antibody against the selected HLB biomarker for isolation and concentration. Performing analytical characterization of nanogap electrode conductivity sensor for HLB biomarker. Testing and validating the sensor using HLB-infected citrus samples.

approach

  • Generate high affinity antibodies against secreted proteins of Ca. Liberibacter and select one secreted protein as the biomarker for HLB. Fabricate a pair of graphene electrodes separated by nanometer gap distance. Perform site specific immobilization of one antibody against the selected HLB biomarker in the nanogap between the graphene electrodes. Synthesize magnetic core-gold shell nanoparticles and functionalizing them with second antibody against the selected HLB biomarker for isolation and concentration. Perform analytical characterization of nanogap electrode conductivity sensor for HLB biomarker. Test and validate the sensor using HLB-infected citrus samples.

description

  • The multi-billion dollars citrus industry in U.S. and Worldwide is at grave risk of irrepairable damage from citrus greening disease, also called Huanglongbing (HLB). This deadly disease is caused by the bacterial pathogen Candidatus Liberibacter for which currently there is no cure and management is heavily dependent on early detection. Current methods of HLB detection, which are based on disease symptoms and nucleic acid assay, are not only inaccurate but also unsuitable for field surveys due to variable latent time and sporadic distribution of the pathogen in infected trees. The objective of the proposed research is to develop a point-of-use immunosensor for highly sensitive and selective, facile, rapid, cost-effective and quantitative detection of a HLB biomarker in tree phloem extract. We will target proteins secreted by Ca. Liberibacter as candidate biomarkers as these proteins can systemically distribute in the infected trees, therefore providing direct, selective and reliable detections of HLB. To detect the HLB biomarker we will develop a novel electrical nanobiosensor that will detect the antigen based on change in electrical conductivity resulting from bridging of a nanogap by the trapping of nanoparticle. This nanosensor will address critical and urgent need of the multi-billion dollars citrus industry and food security issues by providing a highly sensitive and selective analytical tool for simple, rapid and low cost detection of citrus greening disease.

Background

performing institution

  • REGENTS OF THE UNIVERSITY OF CALIFORNIA AT RIV

Time

date/time interval

  • December 1, 2013 - November 30, 2016