Functionalization of Gold Nanoparticles with Zn(II)-Salophen complexes for the development of Plasmonic Nanosensors in water

A. Fantoni1,2, G. Bruylants2, A. Dalla Cort1

1 Dipartimento di Chimica e Istituto CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione, Rome, Italy;
2 Engineering of Molecular NanoSystems (EMNS), Université libre de Bruxelles (ULB), Brussels, Belgium

The development of molecular sensors that can selectively bind analytes in an aqueous environment is an important and topical field of research constantly fuelled by applications ranging from environmental monitoring to biology and medicine.

In this regard, dicarboxylic acids are important targets for molecular recognition and sensing due to the importance they have in biological and industrial processes.[1,2] It has been shown that increased levels of these species in the hydrosphere can be potentially harmful for the environment and poses health concerns.[3] Although considerable progress has been made in the development of receptors and sensors for dicarboxylic acids in organic solvents,[1] the synthesis of receptors capable of performing their function in an aqueous and biologically relevant environment remains a challenge. Receptors are often large organic molecules with hydrophobic characteristics and are at best poorly soluble in water. Furthermore, at biological pH most dicarboxylic acids exist in their deprotonated form and the negative charge of the carboxylates gives it a high solvation energy, making the design of efficient host-guest interactions particularly difficult.

In this context, we are developing new colorimetric sensors for dicarboxylate species in water based on Zn(II)-Salophen complexes bearing suitable functional groups, that are known to present good affinities towards carboxylic groups in organic solvents,[4] grafted on gold nanoparticles. This method allows to combine the advantageous properties of AuNPs with the versatility of salophen complexes to obtain efficient colorimetric sensors capable of performing this task in aqueous solutions. Different strategies for the functionalization gold nanoparticles with Zn(II)-Salophen complexes will be reported as well as the evaluation of these hybrid nanostructures for the sensing of aliphatic dicarboxylates in water.

1. S. M. Butler, K. A. Jolliffe, Org. Biomol. Chem., 2020, 18, 8236.
2. D. Curiel, M. Más-Montoya, G. Sánchez, Coordination Chemistry Reviews, 2015, 284, 19–66.

3. M.S. Parmar, Encyclopedia of Toxicology (Third Edition), 2014, 76-79.
4. A. Dalla Cort, P. De Bernardin, L. Schiaffino, Chirality, 2009, 21, 104–109.