We develop the use of Raman spectroscopy for non-invasive, non-destructive, and confirmatory diagnostics of biotic and abiotic stresses on plants. We use cutting-edge technology, including tip-enhanced Raman spectroscopy and atomic force infrared spectroscopy, to unravel structural organization of biological systems at the nanoscale.

Diagnostics of biotic and abiotic stresses on plants

As the human population grows from its current size of 7 billion to the projected 9.7 billion in 2050, we will need to produce ~70% more food. These demands can be met by continuous improvement of crop productivity and minimization of losses associated with biotic and abiotic stresses. However, all currently available technologies for detection of plant disease, drought, or nutrient deficiencies are either inefficient or too expensive for farmers and plant breeders. To overcome this problem, we propose to develop the use of Raman spectroscopy (RS) for confirmatory and non-invasive diagnostics of biotic and abiotic stresses on plants. Using RS, we aim to achieve rapid, label-free, non-invasive and quantitative diagnostics of viral, bacterial, and fungal diseases on a large variety of plant species. We also develop RS for pre-symptomatic diagnostics of abiotic stresses, including drought and nutrient deficiencies caused by a lack of nitrogen, phosphorus, and potassium. Lastly, we explore the potential of RS for non-invasive plant phenotyping. Our ultimate goal is to make this Raman-based diagnostic approach broadly available for farmers and plant breeders in the U.S and abroad. 

C. Farber, L. Sanchez, S. Rizevsky, A. Ermolenkov, B. McCutchen, J. Cason, C. Simpson, M. Burow, D. Kurouski, Raman spectroscopy enables non-invasive identification of peanut genotypes and value-added traits. Sci. Rep. 10 (2020).

Elucidation of structure and dynamics of biological systems

Amyloid oligomers and viruses are structurally heterogeneous species that either cause or directly link to numerous diseases such as Alzheimer’s and Parkinson’s disease, AIDS, rabies, and influenza. Amyloid oligomers are intrinsically unstable protein species that exhibit high structural heterogeneity and present only at low sub-nanomolar concentrations; similar structural heterogeneity has been observed in viruses. Self-assembly of these protein-nucleic acid systems often occurs with multiple miss-assembly steps resulting in the formation of aberrant structures. Alternatively, several structurally different forms of the same virus can be simultaneously formed. Such structurally different viral forms have different virulence. We elucidate structure and dynamics of viruses and amyloid oligomers using two modern optical nanoscopy techniques: Atomic Force Microscope Infrared (AFM-IR) and Tip-Enhanced Raman Spectroscopy (TERS). Our goal is to reveal the relationship between structure and toxicity or virulence of these pathogenic species.

S. Rizevsky, D. Kurouski, Nanoscale structural organization of insulin fibril polymorphs revealed by atomic force microscope infrared spectroscopy (AFM-IR). ChemBioChem 20, 481–485 (2019).

C. Farber, R. Wang, R. Chemelewski, J. Mullet, D. Kurouski, Nanoscale structural organization of plant epicuticular wax probed by atomic force microscope infrared spectroscopy. Analyt. Chem. 91, 2472–2479 (2019).

Plasmon chemistry

Plasmonic catalysis is a new emerging direction in organic synthesis. It is based on a unique property of noble metal nanostructures to harvest electromagnetic radiation converting it into hot carriers. These high-energy species can catalyze chemical reactions in molecules located in the vicinity to surfaces of the plasmonic nanostructures. Traditional plasmonic metals such as gold and silver are useful only for a limited number of chemical reactions. Common catalytic metals such as palladium or platinum provide a much broader spectrum of chemical transformations. However, these catalytic metals are not efficient in harvesting electromagnetic radiation. The new paradigm of solid-state catalysis is that coupling of plasmonic and catalytic metals can be used to achieve much higher catalytic efficiency relative to their counterparts. Also, chemical reactions on such bimetallic nanostructures are light-driven, which essentially enables ‘green catalysis’ in organic synthesis. Catalytic efficiency of bimetallic platforms directly depends on their nanoscale structure, which remains poorly understood. Using TERS, we investigate nanoscale catalytic properties of such bimetallic nanostructures. Our goal is to investigate the relationship between nanoscale structural organization of bimetallic nanostructures and their catalytic activity.

R. Wang, Z. He, A. Sokolov, D. Kurouski, Gap-mode tip-enhanced raman scattering on au nanoplates of varied thickness. J. Phys. Chem. Lett. 11, 3815–3820 (2020).

R. Wang and D. Kurouski, Thermal reshaping of gold microplates: three possible routes and their transformation mechanisms. ACS Appl. Mater. Interfaces 11, 41813–41820 (2019).