Dye-Doped Silica Nanoparticles for Enhanced ECL-Based Immunoassay Analytical Performance
Authors: Rebeccani Sara , Zanut Alessandra , Palomba Francesco , Rossi Scota Matilde , Marcaccio Massimo , Genovese Damiano , Rampazzo Enrico , Valenti Giovanni , Paolucci Francesco , Prodi Luca 
Published: July 2021

Electrochemiluminescence (ECL) is a leading technique in bioanalysis.[1] It is a luminescent phenomenon where the excited species are produced with an electrochemical stimulus rather than with a light excitation source. For this reason, ECL displays improved signal-to-noise ratio compared to photoluminescence, with minimized effects due to light scattering and luminescence background.[2]
Chasing ever-increasing sensitivities, ECL can ideally be coupled to nanotechnology to develop new strategies for clinical applications and analyte determination also in real and complex matrices.[3] In particular, dye-doped silica nanoparticles (DDSNs) present many advantages: they can be easily synthesized, are hydrophilic and are prone to bioconjugation thanks to silica chemistry. With this approach we were able to achieve extremely bright systems and DDSNs allow the 8.5 fold increase of ECL intensity.[4] In DDSNs, light emission is influenced by the combination of several factors that make DDSNs complex multichromophoric structures. However, when ECL comes into play, the scenario is even more complicated due to the coreactant−NP interactions effect. Such complex scenario was approached at the theoretical level by developing suitable mechanistic models for ECL generation[5] while, at the same time, the influence of doping level on ECL efficiency was evaluated. Our results showed that the ECL intensity of a nanosized system cannot be merely incremented acting on doping, since other parameters come into play. These studies support the application in ECL microscopy providing valuable indications for the design of more efficient ECL nano- and micro-sized labels towards more sensitive ECL-based immunoassay for bioanalysis applications. [6]
References
[1] W. Miao, “Electrogenerated Chemiluminescence and Its Biorelated Applications”, Chem. Rev., 2008, vol. 108, pp. 2506–2553.
[2] Z. Liu, W. Qi, G. Xu, “Recent advances in electrochemiluminescence”, Chem. Soc. Rev., 2015, vol. 44, pp. 3117–3142.
[3] C. Ma, Y. Cao, X. Gou, J. J. Zhu, “Recent progress in electrochemiluminescence sensing and imaging”, Anal. Chem., 2015, vol. 92, pp. 431-454.
[4] G. Valenti, E. Rampazzo, S. Bonacchi, L. Petrizza, M. Marcaccio, M. Montalti, L. Prodi, F. Paolucci, “Variable Doping Induces Mechanism Swapping in Electrogenerated Chemiluminescence of Ru(bpy) 3 2+ Core–Shell Silica Nanoparticles”, J. Am. Chem. Soc., 2016, vol. 138, pp. 15935–15942.
[5] E. Daviddi, A. Oleinick, I. Svir, G. Valenti, F. Paolucci, C. Amatore, “Theory and Simulation for Optimising Electrogenerated Chemiluminescence from Tris(2,2′-bipyridine)-ruthenium(II)-Doped Silica Nanoparticles and Tripropylamine”, ChemElectroChem, 2017, vol. 4, pp. 1719–1730.
[6] A. Zanut, F. Palomba, M. Rossi Scota, S. Rebeccani, M. Marcaccio, D. Genovese, E. Rampazzo, G. Valenti, F. Paolucci, L. Prodi, "Dye‐Doped Silica Nanoparticles for Enhanced ECL‐Based Immunoassay Analytical Performance", Angew. Chemie Int. Ed., 2020, vol. 132, pp. 22042-22047

Figure 1