Environmental sensing

 
 

Enabling Technology: Nanomaterials

 

Our work in the sensing area has focused on the development and testing of three novel technological solutions to sense biological and chemical constituents:


1. Nano-Immuno-Magnetic Detection of Bacteria


The driver for this work was to develop and validate a technology sufficiently sensitive to detect Mycobacterium immunogenum at 1,000 cells/ml in metal working fluids (MWF).  MWF are oil-in-water based coolants using in the metalworking industry (for more on this topic, please see the work by Professor Steven Skerlos at The University of Michigan).  They tend to be prone to microbial spoiling, resulting in elevated bacterial growths.  Recent work has indicated that M. immunogenum might be the culprit causing hypersensitivity pneumonitis (HP) resulting from inhalation of these cells or their endotoxins by metalworkers.


NIM-based detection, coupled to flow cytometric detection, is based on the conjugation of fluorochrome-enabled antibodies to magnetite-based nanoparticles.  These “nanobeads” bind to the microbial cell membranes, which allows the cell-bead particle to be detected using optical detection methods such as flow cytometry.  For more details, please see:


  1. 1.Chang, S.-C. and P. Adriaens.  2007.  Nano-Immunodetection and Quantification of Mycobacteria in Metalworking Fluids, Environ. Eng. Sci., 24, 58-72.

  2. 2.Chang, S-C, Anderson,T., Bahrman, S, Gruden CL, Khijniak1,AI, Adriaens, P. 2005. Comparing recovering efficiency of immunomagnetic separation and centrifugation of mycobacteria in metalworking fluids. J. Ind. Microbiol. Biotechnol. 32: 629-638.

  3. 3.Chang, S.-C.,  A.N. Rihana, S. Bahrman, C. Gruden, A.I. Khijniak, S.J. Skerlos, and P. Adriaens.  2004.  Flow Cytometric Detection and Quantification of Mycobacteria in Metalworking Fluids.  Int. J. Biodet. Biodeg., 54: 105-112.


2.  DNA Aptamers for Heavy Metal Detection


This work was performed to address the need for redox-specific detection of toxic species in environmental systems, as an alternative to the sequential extraction and the acid volatile sulfide (AVS) methods.


DNAzymes (or catalytic DNA) are cell-free biomolecular recognition tools to quantify the bioavailability of charged species such as metal ions, antibiotics, and pharmaceuticals. Using in vitro selection or SELEX (Systematic Evolution of Ligands by EXponential amplification), large populations (e.g. 1015) of random DNA sequences are used as the raw material for the selection of “functional molecules” or “aptamers”, generally ranging from 20 to 50 nucleotides in length which exhibit a high specificity to target metals. Since the catalytic activity can be characterized in terms of metal specificity, and in terms of affinity, the catalytic DNA serves as a sensor.  The sensors can be applied in solution or embedded on gold particles for enhanced signal amplification, rendering them amenable to in situ applications.


1.Vannela, R., and P. Adriaens.  2007. In Vitro Selection of Hg (II) and As (V)-Dependent RNA-Cleaving DNAzymes, Env. Eng. Sci., 24, 73-84.