About

Allison Henry is a Clinical Assistant Professor of Management & Organizations and the Director of the Golub Capital Board Fellows program at Kellogg School of Management at Northwestern University. She teaches in a graduate program at the School of Communications at Northwestern University and occasionally in executive education programs led by Kellogg's Center for Nonprofit Management. Her career spans the private, public, and social sectors, with notable roles including Executive Director of The People’s Music School, where she led strategy, finance, operations, human resources, evaluation, and fundraising, overseeing significant growth and national recognition. Alli’s professional background includes consulting at Bain & Company, advising Fortune 500 companies across various industries, and building entrepreneurial organizations with a focus on social impact, such as Mission Measurement and A Better Chicago. She holds an MBA from Kellogg School of Management and a double major in Mathematics and Economics from Grinnell College.

Research topics

• Materials science
• Nanotechnology
• Chemistry
• Crystallography
• Optics

Selected publications

• RETRACTED

  Retraction of “Bisboronic Acids for Selective, Physiologically Relevant Direct Glucose Sensing with Surface-Enhanced Raman Spectroscopy”

  Journal of the American Chemical Society · 2024-11-18

  retraction
  PublisherOA PDFDOI

• Plasmonic Microneedle Arrays for in Situ Sensing with Surface-Enhanced Raman Spectroscopy (SERS)

  Nano Letters · 2019-09-23 · 140 citations

  articleOpen access

  Surface-enhanced Raman spectroscopy (SERS) is a sensitive, chemically specific, and short-time response probing method with significant potential in biomedical sensing. This paper reports the integration of SERS with microneedle arrays as a minimally invasive platform for chemical sensing, with a particular view toward sensing in interstitial fluid (ISF). Microneedle arrays were fabricated from a commercial polymeric adhesive and coated with plasmonically active gold nanorods that were functionalized with the pH-sensitive molecule 4-mercaptobenzoic acid. This sensor can quantitate pH over a range of 5 to 9 and can detect pH levels in an agar gel skin phantom and in human skin in situ. The sensor array is stable and mechanically robust in that it exhibits no loss in SERS activity after multiple punches through an agar gel skin phantom and human skin or after a month-long incubation in phosphate-buffered saline. This work is the first to integrate SERS-active nanoparticles with polymeric microneedle arrays and to demonstrate in situ sensing with this platform.

  PublisherOA PDFDOI

• Physicochemical Trapping of Neurotransmitters in Polymer-Mediated Gold Nanoparticle Aggregates for Surface-Enhanced Raman Spectroscopy

  Analytical Chemistry · 2019-06-24 · 34 citations

  article

  Because of the sharp distance dependence of surface-enhanced Raman spectroscopy (SERS), analyte molecules that do not exhibit strong affinity for Au/Ag often elude detection. New methods of integrating such analytes with SERS substrates are required to circumvent this limitation and expand the sensitivity of SERS to new molecules and applications. We communicate here a solution-phase, capture agent-free method of aggregating Au nanospheres in the presence of five neurotransmitters (dopamine, epinephrine, norepinephrine, serotonin, and histamine) and preventing sedimentation by encapsulating the aggregated nanospheres with polyvinylpyrrolidone, thereby trapping the neurotransmitters in close proximity to the Au nanospheres and enabling SER detection. The primary advantages of this physicochemical trapping method, which is generalizable to analytes beyond the scope of this work, are the high signal-to-noise ratio and spectral consistency down to nM levels. Normal Raman spectra and density functional theory calculations corroborate the accuracy of the spectra. Spectra collected over a wide range of concentrations were used to construct adsorption isotherms for all five neurotransmitters, from which adsorption dissociation constants were calculated, spanning from 5.7 × 10–4 M to 1.7 × 10–10 M. We expect this method to produce high quality SER spectra of any molecule with an Au affinity known or expected (based on functional groups) to be within that range. Our results have implications for plasmonic detection of these neurotransmitters, particularly for mixtures of those that exhibited disparate Au affinity in our study. We also present evidence that this method produces spectra of sufficient resolution to explore hypotheses related to surface adsorption behavior.

  PublisherDOI

• Unraveling the Near- and Far-Field Relationship of 2D Surface-Enhanced Raman Spectroscopy Substrates Using Wavelength-Scan Surface-Enhanced Raman Excitation Spectroscopy

  The Journal of Physical Chemistry C · 2017-06-22 · 27 citations

  article

  Lithographic and nonlithographic two-dimensional (2D) substrates for surface-enhanced Raman spectroscopy (SERS) have gained enormous popularity as analytical platforms for detection and identification of various analytes. However, their near- and far-field properties in most cases remain poorly understood. We have previously developed a metal nanopillar film over nanospheres (FON) platform exhibiting Raman enhancement factors of ∼107. These substrates have a reproducible and predictable localized surface plasmon resonance throughout the entire visible region and much of the near-IR region of the electromagnetic spectrum. Extending upon these results, we have utilized wavelength-scan surface-enhanced Raman excitation spectroscopy to unravel the relationship between near- and far-field properties of FON surface-enhanced Raman spectroscopy substrates. We examined by scanning electron microscopy FONs fabricated by either stationary (ST-FONs) or spun (SP-FONs) metal deposition to examine the interrelationships of nanoscale structure and near- and far-fied properties. We demonstrate that the line width and spectral position of the far-field and near-field resonances of ST- and SP-FONs directly depend on the nanofeature distribution at the metallic surface. In particular, we show that the actual nanofeature morphology and distribution directly impact the spectral alignment of the far-field and near-field resonances.

  PublisherDOI

• Spiers Memorial Lecture : Surface-enhanced Raman spectroscopy: from single particle/molecule spectroscopy to ångstrom-scale spatial resolution and femtosecond time resolution

  Faraday Discussions · 2017-01-01 · 25 citations

  article1st author

  Four decades on, surface-enhanced Raman spectroscopy (SERS) continues to be a vibrant field of research that is growing (approximately) exponentially in scope and applicability while pushing at the ultimate limits of sensitivity, spatial resolution, and time resolution. This introductory paper discusses some aspects related to all four of the themes for this Faraday Discussion. First, the wavelength-scanned SERS excitation spectroscopy (WS-SERES) of single nanosphere oligomers (<italic>viz.</italic>, dimers, trimers, <italic>etc.</italic>), the distance dependence of SERS, the magnitude of the chemical enhancement mechanism, and the progress toward developing surface-enhanced femtosecond stimulated Raman spectroscopy (SE-FSRS) are discussed. Second, our efforts to develop a continuous, minimally invasive, <italic>in vivo</italic> glucose sensor based on SERS are highlighted. Third, some aspects of our recent work in single molecule SERS and the translation of that effort to ångstrom-scale spatial resolution in ultrahigh vacuum tip-enhanced Raman spectroscopy (UHV-TERS) and single molecule electrochemistry using electrochemical (EC)-TERS will be presented. Finally, we provide an overview of analytical SERS with our viewpoints on SERS substrates, approaches to address the analyte generality problem (<italic>i.e.</italic> target molecules that do not spontaneously adsorb and/or have Raman cross sections &lt;10⁻²⁹ cm² sr⁻¹), SERS for catalysis, and deep UV-SERS.

  PublisherDOI

• Surface-Enhanced Raman Spectroscopy Biosensing:<i>In Vivo</i>Diagnostics and Multimodal Imaging

  Analytical Chemistry · 2016-06-06 · 218 citations

  article1st authorCorresponding

  This perspective presents recent developments in the application of surface-enhanced Raman spectroscopy (SERS) to biosensing, with a focus on in vivo diagnostics. We describe the concepts and methodologies developed to date and the target analytes that can be detected. We also discuss how SERS has evolved from a "point-and-shoot" stand-alone technique in an analytical chemistry laboratory to an integrated quantitative analytical tool for multimodal imaging diagnostics. Finally, we offer a guide to the future of SERS in the context of clinical diagnostics.

  PublisherDOI

• Ultrahigh-Vacuum Tip-Enhanced Raman Spectroscopy

  Chemical Reviews · 2016-12-22 · 158 citations

  reviewOpen access

  Molecule-surface interactions and processes are at the heart of many technologies, including heterogeneous catalysis, organic photovoltaics, and nanoelectronics, yet they are rarely well understood at the molecular level. Given the inhomogeneous nature of surfaces, molecular properties often vary among individual surface sites, information that is lost in ensemble-averaged techniques. In order to access such site-resolved behavior, a technique must possess lateral resolution comparable to the size of surface sites under study, analytical power capable of examining chemical properties, and single-molecule sensitivity. Tip-enhanced Raman spectroscopy (TERS), wherein light is confined and amplified at the apex of a nanoscale plasmonic probe, meets these criteria. In ultrahigh vacuum (UHV), TERS can be performed in pristine environments, allowing for molecular-resolution imaging, low-temperature operation, minimized tip and molecular degradation, and improved stability in the presence of ultrafast irradiation. The aim of this review is to give an overview of TERS experiments performed in UHV environments and to discuss how recent reports will guide future endeavors. The advances made in the field thus far demonstrate the utility of TERS as an approach to interrogate single-molecule properties, reactions, and dynamics with spatial resolution below 1 nm.

  PublisherOA PDFDOI

• Single-Molecule Chemistry with Surface- and Tip-Enhanced Raman Spectroscopy

  Chemical Reviews · 2016-12-08 · 709 citations

  reviewOpen access

  Single-molecule (SM) surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) have emerged as analytical techniques for characterizing molecular systems in nanoscale environments. SERS and TERS use plasmonically enhanced Raman scattering to characterize the chemical information on single molecules. Additionally, TERS can image single molecules with subnanometer spatial resolution. In this review, we cover the development and history of SERS and TERS, including the concept of SERS hot spots and the plasmonic nanostructures necessary for SM detection, the past and current methodologies for verifying SMSERS, and investigations into understanding the signal heterogeneities observed with SMSERS. Moving on to TERS, we cover tip fabrication and the physical origins of the subnanometer spatial resolution. Then, we highlight recent advances of SMSERS and TERS in fields such as electrochemistry, catalysis, and SM electronics, which all benefit from the vibrational characterization of single molecules. SMSERS and TERS provide new insights on molecular behavior that would otherwise be obscured in an ensemble-averaged measurement.

  PublisherOA PDFDOI
• RETRACTED

  RETRACTED: Bisboronic Acids for Selective, Physiologically Relevant Direct Glucose Sensing with Surface-Enhanced Raman Spectroscopy

  Journal of the American Chemical Society · 2016-09-26 · 118 citations

  article

  This paper demonstrates the direct sensing of glucose at physiologically relevant concentrations with surface-enhanced Raman spectroscopy (SERS) on gold film-over-nanosphere (AuFON) substrates functionalized with bisboronic acid receptors. The combination of selectivity in the bisboronic acid receptor and spectral resolution in the SERS data allow the sensors to resolve glucose in high backgrounds of fructose and, in combination with multivariate statistical analysis, detect glucose accurately in the 1-10 mM range. Computational modeling supports assignments of the normal modes and vibrational frequencies for the monoboronic acid base of our bisboronic acids, glucose and fructose. These results are promising for the use of bisboronic acids as receptors in SERS-based in vivo glucose monitoring sensors.

  PublisherDOI

• High-Resolution Distance Dependence Study of Surface-Enhanced Raman Scattering Enabled by Atomic Layer Deposition

  Nano Letters · 2016-05-31 · 170 citations

  article

  We present a high-resolution distance dependence study of surface-enhanced Raman scattering (SERS) enabled by atomic layer deposition (ALD) at 55 and 100 °C. ALD is used to deposit monolayers of Al2O3 on bare silver film over nanospheres (AgFONs) and AgFONs functionalized with self-assembled monolayers. Operando SERS is used to measure the intensities of the Al-CH3 and C-H stretches from trimethylaluminum (TMA) as a function of distance from the AgFON surface. This study clearly demonstrates that SERS on AgFON substrates displays both a short- and long-range nanometer scale distance dependence. Excellent agreement is obtained between these experiments and theory that incorporates both short-range and long-range terms. This is a high-resolution operando SERS distance dependence study performed in one integrated experiment using ALD Al2O3 as the spacer layer and Raman label simultaneously. The long-range SERS distance dependence should make it possible to detect chemisorbed surface species located as far as ∼3 nm from the AgFON substrate and will provide new insight into the surface chemistry of ALD and catalytic reactions.

  PublisherDOI

Frequent coauthors

• Richard P. Van Duyne

  29 shared

• George C. Schatz

  Northwestern University

  17 shared

• M. P. Pileni

  Sorbonne Université

  12 shared

• Alexa Courty

  Sorbonne Université

  12 shared

• Nicolas Goubet

  Sorbonne Université

  8 shared

• Kristin L. Wustholz

  William & Mary

  7 shared

• Michael J. Natan

  7 shared

• Bhavya Sharma

  7 shared

Awards & honors

• Sidney J Levy Award for Excellence in Teaching, 2024-25
• Sidney J. Levy Award for Excellence in Teaching, 2021-22