Poly(N-isopropylacrylamide) coated gold nanoparticles as colourimetric temperature and salt sensors

Abstract

Thermoresponsive PNIPAM coated AuNPs having dual stabilisation by the polymer chains and the charges, has been utilised for the development of temperature and salt sensors.

Stimuli-responsive polymers and their applications

“…In one example, Hoogenboom and coworkers developed a colorimetric temperature and salt sensor by coating Au nanoparticles (AuNPs) with a thermoresponsive pNIPAm shell. 68 The pNIPAm polymer was synthesized by RAFT polymerization using methyl 2-(((butylthio)carbonothioyl)thio)propanoate (MBTTC) as a chain transfer agent (CTA), and further grafted to the AuNP surface by a ligand exchange process. When exposed to solutions of different salt concentrations, the pNIPAm modified AuNPs were able to change color from red to purple or blue at elevated temperatures, as shown schematically in Fig.…”

The Crucial Role of Charge in Thermoresponsive‐Polymer‐Assisted Reversible Dis/Assembly of Gold Nanoparticles

“…Tremendous efforts have been devoted to the assembly of gold nanoparticles (AuNPs) because of their intriguing plasmonic properties for many applications as well as their suitability as a model system to understand the colloidal self‐assembly process . Particularly interesting is reversible self‐assembly, which creates multistable nanoconfigurations under different conditions, and provides a potential route toward exploiting colloid lattices for information storage and color switches in sensing and displays . A common approach is to use thermoresponsive polymers such as poly( N ‐isopropylacrylamide) (PNIPAM) to tune the plasmonic resonance of AuNPs, either via changes in their separation or their dielectric environment .…”

Thermally Responsive Materials for Bioimaging

“…[22] Meanwhile, the change of the conformation of thermally responsive polymers can be translated into detectable opticalp ropertyv ariations,w hich could be further appliedf or biosensing. [23] Hoogenboom et al [24] designed at emperature sensorb yc oating at emperature-responsive PNIPAM shell onto Au nanoparticles (AuNPs), which was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, and furtherg raftedo nto the AuNP surface through the ligand exchangep rocess. The modified AuNPs could change their color from red to blue or purpleu pon temperature increasingw hen exposed to salt solutionsw ith different concentrations.…”