Mixed-Ligand Metallic Nanoparticle Based Sensing: when 1+1 > 2

Offer Zeiri, NRCN, Omer, Israel (offerz@nrcn.gov.il)

Metallic nanoparticles, with sizes of 1-100 nm, display unique properties compared to their corresponding bulk materials. These properties, including high-surface-area and surface plasmon resonance, make MNPs very well suited for use in chemical and biological sensing applications. The properties of MNPs could be generally divided into those determined by the metallic particle core, and those determined by the stabilizing ligand monolayer surrounding the particle core. For example, particle solubility, stability, and functionality are all determined by the ligands forming the monolayer. While such monolayers are commonly composed of a single type of ligand molecule, the last two decades have seen great advancements the in fundamental understanding and applications of metallic nanoparticles stabilized by mixed-ligand monolayers. Mixed-ligand monolayers can be composed of two or more types of ligand molecules. Identifying and controlling the organization of multiple ligands in the nanoparticle monolayer has been studied, and its effect on particle properties examined. Mixed-ligand protected particles have since shown advantages over mono-ligand protected particles in fields such as catalysis, self-assembly, imaging, and drug delivery.

In this talk, the use of mixed-ligand monolayer-protected nanoparticles for sensing applications will be examined. Mixed-ligands nanoparticle-based sensors are revealed to be divided into four groups[1], each of which will be discussed. The first group consists of ligands that work cooperatively to improve the sensors’ properties. In the second group, multiple ligands are utilized for sensing multiple analytes. The third group combines ligands used for analyte recognition and signal production. In the final group a sensitive, but unstable, functional ligand is combined with a stabilizing ligand. Finally, future challenges and potential research directions for this promising subject will be presented.

[1] Metallic nanoparticle-based sensing: utilization of mixed-ligand monolayers, Offer Zeiri, ACS Sensors, 2020