Final Report: LSPR Nano-Immunosensor for Simple and Sensitive Water Monitoring

EPA Contract Number: EPD08036
Title: LSPR Nano-Immunosensor for Simple and Sensitive Water Monitoring
Investigators: Bastiaans, Glenn J.
Small Business: Intelligent Optical Systems Inc.
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: March 1, 2008 through August 31, 2008
Project Amount: $69,998
RFA: Small Business Innovation Research (SBIR) - Phase I (2008) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Nanotechnology


The overall goal of this project was to demonstrate the feasibility of developing a water monitoring system using simple optical measurements with a special sensor known as a localized surface plasmon resonance (LSPR) device. To  emonstrate feasibility in this Phase I work, assays were developed for the organism E. coli and the toxin Microcystin LR. The following objectives were proposed:

Objective 1. Demonstrate LSPR Assay for a Toxin

Objective 2. Demonstrate LSPR Assay for a Bacterium

Objective 3. Demonstrate Assays in Flowing Water

Objective 4. Estimate the Cost to Deploy and Operate LSPR Water Monitor


This project was highly successful with all proposed tasks being completed and all objectives of the Phase I proposal being achieved.

In the research work, a prototype laboratory system was developed to make optical measurements at multiple small "spot" locations on an LSPR substrate to demonstrate the capability to determine the concentrations of many different water contaminants using one sensor array and one volume of sample.  This optical measurement system uses principles similar to commercial microplate readers so that it can be readily commercialized in a simpler, lower cost form.

Summary/Accomplishments (Outputs/Outcomes):

To demonstrate assays, larger LSPR nanoplate array substrates were developed and fitted with low cost customized flow cells.  Using the principles of immunoassay, it was shown that the immunogenic binding of target analytes (E. coli and Microcystin LR) to the surfaces of the silver nanoplate arrays of the LSPR devices generated an optical response, even at low concentrations of the analytes.  Thus, sensitive assays for E. coli and Microcystin LR were demonstrated.

For the Microcystin LR assay, it was estimated that the limit of detection was 0.01 ng/mL (0.01 ppb or 10 parts per trillion).  This concentration is well below proposed limits for Microcystin LR in drinking water.  In the case of E. coli, the LSPR-based assay was also successful in detecting this organism in small volumes of sample.  It was estimated that the limit of detection was 46 colony forming units.  This level of detectability is highly favorable, because a real-time method does not rely on the time-consuming growth of bacteria in culture, or other concentration methods.

Analysis of LSPR sensor responses showed that low concentrations of analytes generate proportionately larger sensor response as predicted by the theory describing the binding of molecules to surfaces.  This characteristic is favorable for sensing applications because it generates sensitive responses.

The evaluation of a displacement immunoassay strategy for sensing, in addition to a direct immunoassay design, showed that highly sensitive responses can be generated via the direct immunological binding of target analytes to the surface.  The effectiveness of a displacement immunoassay approach was found to be highly dependent on the antibody chosen for the assay system.


Significant progress was made in demonstrating the commercial feasibility of the proposed water contaminant monitoring system in four areas:  market identification and evaluation, identification of pathways for testing and validation, initial negotiation of a collaborative arrangement for product manufacture, marketing, and sales, as well as the establishment of cost and price goals for a commercial LSPR system.  Intelligent Optical Systems (IOS) is currently in discussions with a large manufacturer of environmental assay instrumentation with the goal of establishing a Phase II collaboration.

The envisioned product is projected to be highly innovative because the sensors will be simple planar arrays of glass or plastic that do not require the addition of any reagents, but instead require only samples and standards.  The optical measurements are easily made by operators that have received only minimal training.  Support instrumentation can be made portable for field use.  Costs per assay are expected to be very competitive.  Given all the positive factors for this technology, IOS feels that the successful development of the LSPR technology is highly feasible.

Supplemental Keywords:

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