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Detection and Identification of Plant Diseases Using a Hand-Held Raman Spectrometer

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Continuous growth of the human population makes global food security a critical aspect for maintaining civilization. Currently, over a billion people suffer from malnutrition due to a lack of food. There are several strategies to address this issue. One of them is increasing agricultural land areas. As we will need 70% more food by 2050, this approach is highly inefficient and destructive to nature. The second strategy addresses reducing disease-induced damage in crops during growth, harvest and post-harvest processing. Plant diseases can reduce crop yields by as much as 50%. Timely disease diagnosis will insure precise application of fungicides, reduce costs of pathogen treatment, and increase crop yield.

Raman spectroscopy (RS) is a modern analytical technique that provides information about molecular vibrations and consequently the chemical structure of the analyzed specimen. We recently discovered that RS is capable of non-invasive, non-destructive and confirmatory detection of plant fungal pathogens on maize, wheat and sorghum grain. Our laboratory develops and deploys portable Raman systems for early detection and identification of 1) fungal pathogens that cause major crop losses, 2) viral pathogens and 3) insect parasites on sugar cane, fruits and vegetables.

  • Farber, C. and Kurouski, D. (2018) Detection and Identification of Plant Pathogens on Maize Kernels with a Handheld Raman Spectrometer Anal. Chem.90, 3009-3012.

 


Structural Organization of Amyloid Oligomers

We are broadly interested in elucidation of structural organization of amyloid oligomers using Tip-Enhanced Raman Spectroscopy (TERS).

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Nearly 44 million people around the world are currently diagnosed with Alzheimer’s disease and it is the sixth leading cause of death in the USA. The cause of Alzheimer’s disease and other neurodegenerative maladies is unknown. Consequently, there is no effective treatment against these disorders.

Medical diagnosis is primarily based on movement disorders and signs of memory loss. Such a drastic change in behavior is associated with neuron death and abrupt changes in structures and functions of proteins. These misfolded proteins rapidly aggregate forming highly toxic protein oligomers that further propagate into amyloid fibrils.

The ultimate objective of our studies is to unravel structural elements on surfaces of amyloid oligomers that are responsible for their toxicity and propensity to propagate into amyloid fibrils.   These findings will help to guide pharmaceutical drug screening efforts towards finding selective blockaders of amyloid fibrillation at the stage where their aggregates are minimally toxic. Finally, resolving the structure of amyloid oligomers will give an inside how to cure Alzheimer’s and Parkinson’s diseases and dementia.


Mechanisms and Dynamics of Electrochemical and Electrocatalysis Processes at Nanoscale

We use TERS to investigate electrochemical catalysis at the solid-liquid interface. Understanding the interplay between heterogeneous catalyst structure and reaction dynamics is crucial to strategically increase the performance of batteries, fuel cells, and solar cells.

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Surface structure plays a key role in the efficiency of heterogeneous catalysts and electrochemical processes at the solid-liquid interface. Heterogeneous catalysis in general and electrochemical catalysis in particular are commonly used in organic synthesis and have a very broad application prospective in solar-cells and biotechnology.

TERS offers a unique spatiotemporal characterization of photo- and electrochemical processes at the interfaces. My laboratory interested in unraveling electrochemical and electrocatalytic processes at the nanoscale using TERS. We anticipate that these findings will transform the understanding of numerous fundamental electrochemical processes, including 1) conversion and storage of energy, 2) plasmon driven electron transport, 3) electrocatalysis and photocatalysis, and 4) electron transfer in living systems.


Detection and Identification of Dyes in Forensic.

Hair is one of the most common types of physical evidence found at a crime scene. Forensic examination may suggest a connection between a suspect and a crime scene or victim, or it may demonstrate an absence of such associations. Current hair forensic examinations are primarily based on a subjective microscopic comparison of hair found at the crime scene with a sample of suspect’s hair. Since this is often inconclusive, development of alternative and more accurate hair analysis techniques are critical.

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Surface-Enhanced Raman Spectroscopy (SERS) was recently used to detect and identify artificial dyes can be directly on hair (Kurouski and Van Duyne, Anal. Chem., 2015). It has been shown that SERS can (1) identify whether hair was artificially dyed or not; (2) determine if a permanent or semipermanent colorants were used (3) distinguish the commercial brands that are utilized to dye hair. Moreover, such analysis is rapid, minimally destructive, and can be performed directly at the crime scene.

The long term goal of this project to apply Raman spectroscopy in general and SERS in particular for detection and identification of dyes for forensic purposes.

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