Advanced Applications of Raman Spectroscopy for Environmental Analyses Rebecca Halvorson Lahr Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Civil Engineering Peter J. Vikesland Amy J. Pruden Andrea M. Dietrich Maren Roman November 8, 2013 Blacksburg, VA Keywords: Surface-enhanced Raman spectroscopy (SERS), drop coating deposition Raman (DCDR), cyanotoxin, microcystin-LR, cellular imaging, gold nanoparticles, intracellular biosynthesis, Pseudokirchneriella subcapitata, algae, cellulose, wax-printed microfluidic paper based analytical devices (μPADs) Copyright © 2013 Rebecca Halvorson Lahr Advanced Applications of Raman Spectroscopy for Environmental Analyses Rebecca Halvorson Lahr ABSTRACT Due to an ever-increasing global population and limited resource availability, there is a constant need for detection of both natural and anthropogenic hazards in water, air, food, and material goods. Traditionally a different instrument would be used to detect each class of contaminant, often after a concentration or separation protocol to extract the analyte from its matrix. Raman spectroscopy is unique in its ability to detect organic or inorganic, airborne or waterborne, and embedded or adsorbed analytes within environmental systems. This ability comes from the inherent abilities of the Raman spectrometer combined with concentration, separation, and signal enhancement provided by drop coating deposition Raman (DCDR) and surface-enhanced Raman spectroscopy (SERS). Herein the capacity of DCDR to differentiate between cyanotoxin variants in aqueous solutions was demonstrated using principal component analysis (PCA) to statistically demonstrate spectral differentiation. A set of rules was outlined based on Raman peak ratios to allow an inexperienced user to determine the toxin variant identity from its Raman spectrum. DCDR was also employed for microcystin-LR (MC-LR) detection in environmental waters at environmentally relevant concentrations, after pre-concentration with solid-phase extraction (SPE). In a cellulose matrix, SERS and normal Raman spectral imaging revealed nanoparticle transport and deposition patterns, illustrating that nanoparticle surface coating dictated the observed transport properties. Both SERS spectral imaging and insight into analyte transport in wax-printed paper microfluidic channels will ultimately be useful for microfluidic paper-based analytical device (µPAD) development. Within algal cells, SERS produced 3D cellular images in the presence of intracellularly biosynthesized gold nanoparticles (AuNP), documenting in detail the molecular vibrations of biomolecules at the AuNP surfaces. Molecules involved in nanoparticle biosynthesis were identified at AuNP surfaces within algal cells, thus aiding in mechanism elucidation. The capabilities of Raman spectroscopy are endless, especially in light of SERS tag design, coordinating detection of analytes that do not inherently produce strong Raman vibrations. The increase in portable Raman spectrometer availability will only facilitate cheaper, more frequent application of Raman spectrometry both in the field and the lab. The tremendous detection power of the Raman spectrometer cannot be ignored. Table of Contents Abstract ........................................................................................................................................... ii Table of Contents ........................................................................................................................... iii Table of Figures .............................................................................................................................. v Table of Tables ............................................................................................................................ xiv 1....................................................................................................................................................... 1 Introduction ..................................................................................................................................... 1 2....................................................................................................................................................... 3 Differentiation of Microcystin, Nodularin, and their Component Amino Acids by Drop-Coating Deposition Raman Spectroscopy .................................................................................................... 3 Abstract ....................................................................................................................................... 3 Introduction ................................................................................................................................. 4 Experimental ............................................................................................................................... 6 Results & Discussion .................................................................................................................. 7 Future Outlook .......................................................................................................................... 16 Acknowledgements ................................................................................................................... 17 Supporting Information ............................................................................................................. 17 3..................................................................................................................................................... 36 Microcystin-LR Detection in Environmental Waters at Environmentally Relevant Concentrations ....................................................................................................................................................... 36 Abstract ..................................................................................................................................... 36 Introduction ............................................................................................................................... 37 Experimental ............................................................................................................................. 37 Results & Discussion ................................................................................................................ 38 Future Outlook .......................................................................................................................... 46 Acknowledgements ................................................................................................................... 46 4..................................................................................................................................................... 47 Raman-Based Characterization of Microfluidic Paper-Based Analytical Devices (µPADs) ....... 47 Abstract ..................................................................................................................................... 47 Introduction ............................................................................................................................... 48 Materials & Methods ................................................................................................................. 49 iii Results & Discussion ................................................................................................................ 53 Future Outlook .......................................................................................................................... 65 Acknowledgements ................................................................................................................... 66 Supporting Information ............................................................................................................. 66 5..................................................................................................................................................... 81 Surface-enhanced Raman spectroscopy (SERS) cellular imaging of intracellularly biosynthesized gold nanoparticles ......................................................................................................................... 81 Abstract ..................................................................................................................................... 81 Introduction ............................................................................................................................... 81 Results & Discussion ................................................................................................................ 83 Future Outlook .......................................................................................................................... 95 Materials & Methods ................................................................................................................. 96 Acknowledgements ................................................................................................................... 98 Supporting Information ............................................................................................................. 98 6..................................................................................................................................................