Chelating Phosphine Ligand Stabilized AuNPs in Methane Detection

Abstract

The capping reagent plays an essential role in the functional properties of gold nanoparticles (AuNPs). Multiple stimuli responsive materials are generated via diverse surface modification. The ability of the organic ligand shell on gold surface to create a porous shell capable of binding small molecules is demonstrated as an approach to detect molecules, such as methane, that would be otherwise difficult to sense. Thiols are the most studied capping ligands of AuNPs used in chemiresistors. Phosphine capping groups are usually seemed as stabilizers in synthesis and catalysis. However, by virtue of the pyramidal shape of triarylphosphines, they are natural candidates to create intrinsic voids within the ligand shell of AuNPs. In this work, surface functionalized (capped) AuNPs with chelating phosphine ligands are synthesized via two synthetic routes, enabling chemiresistive methane gas detection at sub-100 ppm levels. These AuNPs are compared to thiol capped AuNPs, and studies were undertaken to evaluate structure-property relationships for their performance in the detection of hydrocarbons. Polymer overcoatings applied to the conductive networks of the functionalized AuNP arrays were shown to reduce resistivity by promoting the formation of conduction pathways with decreased core-core distance between nanoparticles. Observations made in the context of developing methane sensors, provides insight relevant to applications of phosphine or phosphine containing surface groups in functional AuNP materials.

Flexible Plasmonic Biosensors for Healthcare Monitoring: Progress and Prospects

“…This sensing mechanism is based on the change of resistivity (ΔR) of the film by adsorbing the analyte to the chemically sensitive Au NP film, which exhibits high sensitivity for both liquid and gas detections. , It is noteworthy that the selection of thiols on the NP surface plays an important role in the sensitivity and selectivity of Au NP based chemiresistors, which have been widely exercised to optimize the properties of chemiresistors. − …”

Gold nanoparticles (GNPs) in biomedical and clinical applications: A review

“…• Phosphine, a chelating agent can be an excellent building block for gold-nanocluster formations. [101,102] Despite evidence of surface modifications by phosphine, biomedical and therapeutics are not found in the literature.…”

A Versatile Sensing Toolkit for Highly Sensitive Detection through the Electrical Conductivity of Gold Nanoparticles

“…AuNPs have been widely used in detecting analytes including amino acids, nucleic acids, and even single molecules. [ 10,11 ] Most of these sensors are based on the modulation of dispersion and aggregation of AuNPs due to their unique surface plasmon resonance (SPR). The dispersed AuNPs present a red color and the aggregated AuNPs present a blue color.…”

“…[ 13 ] Despite the straightforward readout, these AuNPs‐based optical sensors require complicated surface modification or ligand exchange. [ 11 ] More importantly, the sensitivity of the colorimetric method can be an issue at a low concentration of analyte. The color change of AuNPs might be not effective for highly sensitive detection.…”