Metallic-Nanoparticle-Based Sensing: Utilization of Mixed-Ligand Monolayers

Abstract

The last two decades have seen great advancements in fundamental understanding and applications of metallic nanoparticles stabilized by mixed-ligand monolayers. Identifying and controlling the organization of multiple ligands in the nanoparticle monolayer has been studied, and its effect on particle properties has been examined. Mixed-ligand protected particles have shown advantages over monoligand protected particles in fields such as catalysis, self-assembly, imaging, and drug delivery. In this Review, the use of mixed-ligand monolayer protected nanoparticles for sensing applications will be examined. This is the first time this subject is examined as a whole. Mixed-ligand nanoparticle-based sensors are revealed to be divided into four groups, 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. The Review will conclude by discussing future challenges and potential research directions for this promising subject.

Plasmonic Absorption in Antigen-Induced Aggregated Gold Nanoparticles: Toward a Figure of Merit for Optical Nanosensors

“…1,7,8,10−12 When Au NPs are conjugated with antibodies, the binding of the antigen will induce specific particle aggregation by immunocomplexation. 1,5,7,12,13 While the working principle of Au NP optical sensors is simple and general, there is a list of parameters which influence their response, such as the particle size and shape, interparticle distance, and number and disposition of particles in the aggregate. 14−18 The variety of these parameters has a direct correspondence with the different responses reported so far for this class of detection systems.…”

Bifunctional Calix[4]arene-Coated Gold Nanoparticles for Orthogonal Conjugation

“…An usual method to prepare AuNPs carrying mixed layers of ligands randomly spread over the surface, with a control over the grafting density, consists in the concomitant addition of two different thiol ligands at specific ratios (“simultaneous” method). Due to the lability of the Au–S bond, it was however shown that the resulting ratio of ligands at the surface may greatly differ from that initially introduced in solution. , Another classical method for the formation of mixed layers relies on the stepwise addition of different ligands but, in this case, control over the ligands ratio is complicated to obtain, and this “stepwise” method has been shown to be more adapted to the formation of Janus-like nanoparticles . The limitations of these two methods are particularly problematic for applications requiring multi-functional AuNPs, for example, when both a targeting ligand and a drug have to be anchored on a same particle. − …”

“…20,21 Another classical method for the formation of mixed layers relies on the stepwise addition of different ligands but, in this case, control over the ligands ratio is complicated to obtain, and this "stepwise" method has been shown to be more adapted to the formation of Janus-like nanoparticles. 22 The limitations of these two methods are particularly problematic for applications requiring multi-functional AuNPs, for example, when both a targeting ligand and a drug have to be anchored on a same particle. 23−27 It is known that, upon reduction of their diazonium groups, 28−30 calix [4]arene-tetradiazonium salts 31,32 can form multiple C-metal bonds 33 with the surface of gold or silver nanoparticles, leading to thin and extremely robust organic layers.…”

Diamond-Based Electrodes for Detection of Metal Ions and Anions

“…Detection and quantification of hazardous pollutants, biomolecules, drugs, herbicides, metal ions, and anions are essential to maintaining environmental sustainability [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. A number of methods involving organic nanoprobes, covalent–organic frameworks (COFs), metal–organic frameworks (MOFs), metal nanoparticles, hybrid nanomaterials, small molecules, and polymers were engaged in the quantitation of specific analytes [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ].…”

“…Detection and quantification of hazardous pollutants, biomolecules, drugs, herbicides, metal ions, and anions are essential to maintaining environmental sustainability [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. A number of methods involving organic nanoprobes, covalent–organic frameworks (COFs), metal–organic frameworks (MOFs), metal nanoparticles, hybrid nanomaterials, small molecules, and polymers were engaged in the quantitation of specific analytes [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. On the other end of the spectrum, instrumental tactics, such as inductively coupled plasma mass spectrometry, high-performance liquid chromatography, gas chromatography, atomic absorption spectrometry, electrochemical studies, and immunoassays have been pronounced as the conventional cost-effective approaches [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ].…”