Advanced Materials for Enhanced Vibrational Spectroscopy

Ultrasensitive vibrational spectroscopy techniques allow decisive breakthroughs in many disciplines, including chemistry, physics, materials, and life sciences, because they can provide insightful information about intra- and inter-atomic bonds and physico-chemical processes dynamics. Surface-enhanced Raman scattering (SERS) is a leading non-destructive technique that can extend the sensitivity of Raman spectroscopy to the level of single molecule. However, for several important applications, such as in situ Raman monitoring of chemical reactions, plasmon-based SERS substrates can introduce strong perturbations into the systems under investigation. This prevents extraction of unbiased data and represents a still unsolved major drawback.

Parallely, to more convential plasminic SERS substrates, we are currently investigating alternative approaches to develop new materials based on core/shell multifunctional beads and nanostructures. The goal of this activity is to advance in understanding the mechanisms and dynamics of technology-relevant processes under real working conditions, with a special focus on energy conversion and environmental remediation.

This part of the research activity led to the discovery and development of all-dielectric beads (T-rex) and related core/shell architectures which enabled to develop plasmon-free SERS, with exciting applications for environmental science and bio-diagnostics.

We are also trying to develop new strategies that enable to perform multimodal detection, by combining complementary techniques, such as Raman Spectroscopy+Mass Spectrometry or Raman Spectroscopy+Optical Sensing.

References:

T-rex and related all-dielectric systems:

• Ivano Alessandri, Luca Carletti, Matteo Ferroni, Costantino De Angelis, Irene Vassalini, Bioinspired self-similar all-dielectric antennas: probing the effect of secondary scattering centres by Raman spectroscopy, Materials Advances (2020), 1, 2443-2449, DOI: 10.1039/D0MA00509F

• Irene Vassalini, Orhan Sisman, Elisabetta Comini, Ivano Alessandri, The role of morphology in all-dielectric SERS: A comparison between conformal (T-rex) and non-conformal TiO2 shells, Vibrational Spectroscopy (2020), 109,103085, DOI: 10.1016/j.vibspec.2020.103085

• N. Bontempi,  I. Vassalini, S. Danesi, M. Ferroni, M. Donarelli, P. Colombi, I. Alessandri, Non-plasmonic SERS with silicon: is it really safe? New insights into the optothermal properties of core/shell microbeads, J. Phys. Chem. Lett. (2018), 9, 2127-2132

• N. Bontempi, I. Vassalini, I. Alessandri, All-dielectric core/shell resonators: From plasmon-free SERS to multimodal analysis, J. Raman Spectrosc. (2018), 49, 943-953

• N. Bontempi, I. Vassalini, S. Danesi, I. Alessandri, ZORRO: zirconium oxide resonators for all-in-one Raman and whispering-gallery-mode optical sensing, Chemical Communications (2017), 10.1039/C7CC06357A

• N. Bontempi, E. Biavardi, D. Bordiga, G. Candiani, I. Alessandri*,P. Bergese*, E. Dalcanale*, Probing lysine mono-methylation in histone H3 tail peptides with an abiotic receptor coupled to non-plasmonic resonator, Nanoscale (2017), 9, 8639-8646

• N. Bontempi, K. E. Chong, H. W. Orton, I. Staude, D.-Y. Choi, I. Alessandri, Y. S. Kivshar, D. N. Neshev, Highly sensitive biosensors based on all-dielectric nanoresonators, Nanoscale (2017), 9, 4972-4980, doi: 10.1039/C6NR07904K

• I. Alessandri, J. R. Lombardi, Enhanced Raman Scattering with Dielectrics, Chemical Reviews (2016), doi: 10.1021/acs.chemrev.6b00365

• I. Alessandri, I. Vassalini, M. Bertuzzi, N. Bontempi, M. Memo, A. Gianoncelli, "Ramassays": synergistic enhancement of plasmon-free Raman scattering and mass spectrometry for multimodal analysis of small molecules, Scientific Reports (2016), 6, Article number:34521, doi: 10.1038/srep34521

• N. Bontempi, L. Carletti, C. De Angelis, I. Alessandri, Plasmon-free SERS detection of environmental CO2 on TiO2 surfaces, Nanoscale (2016), DOI: 10.1039/c5nr08380j

• I. Alessandri, E. Biavardi, A. Gianoncelli, P. Bergese, E. Dalcanale, Cavitands Endow All-Dielectric Beads With Selectivity for Plasmon-Free Enhanced Raman Detection of Nε-Methylated Lysine, ACS-Applied Materials & Interfaces (2015), in press, DOI: 10.1021/acsami.5b08190

• N. Bontempi, M. Salmistraro, M. Ferroni, L. E. Depero, I. Alessandri, Probing the spatial extension of light trapping-induced enhanced Raman scattering in high-density Si nanowire arrays, Nanotechnology (2014) 25, 465705.

• Alessandri, N. Bontempi, L. E. Depero, Colloidal lenses as universal Raman scattering enhancers, RSC Advances (2014) 4, 38152-38158.

• Alessandri, L. E. Depero, All-Oxide Raman-Active Traps for Light and Matter: Probing Redox Homeostasis Model Reactions in Aqueous Environment, Small (2014) 10, 1294-1298.

• Alessandri, Enhancing Raman scattering without plasmons: unprecedented sensitivity achieved by TiO2 shell-based resonators, Journal of the American Chemical Society (2013) 135(15), 5541-5544.

Plasmonic SERS-active substrates

• Irene Vassalini, Nicolò Bontempi, Stefania Federici, Matteo Ferroni, Alessandra Gianoncelli, Ivano Alessandri, Cyclodextrins enable indirect ultrasensitive Raman detection of polychlorinated biphenyls captured by plasmonic bubbles, Chemical Physics Letters (2021), 775, 138674, DOI:10.1016/j.cplett.2021.138674

•  I. Vassalini, E. Rotunno, L. Lazzarini, I. Alessandri, “Stainless” gold nanorods: preserving shape, optical properties and SERS activity in oxidative environment, ACS-Applied Materials & Interfaces (2015), 7, 18794-18802.

• G. Sinha, L.E. Depero, I. Alessandri, Recyclable SERS substrates based on Au- coated nanorods, ACS-Applied Materials and Interfaces (2011), 3(7), 2557-2563.

• S. Pal, L. E. Depero, I. Alessandri, Using aggregates of gold nanorods in SER(R)S experiments: an empirical evaluation of some critical aspects, Nanotechnology (2010), 21, 42570.