Poly(N-isopropylacrylamide)-Stabilized Gold Nanoparticles in Combination with Tricationic Branched Phenylene-Ethynylene Fluorophore for Protein Identification

Abstract

Gold nanoparticles stabilized by thermoresponsive polymer, poly(N-isopropylacrylamide) (PNIPAM-AuNPs) were prepared by surface grafting of thiol-terminated PNIPAM onto citrate-stabilized AuNPs. The color change of the PNIPAM-AuNPs solution from red to blue-purple without precipitation when the solution was heated to 40 °C, above the lower critical solution temperature (LCST) of PNIPAM, indicated the thermoresponsive property of the synthesized AuNPs. PNIPAM-AuNPs were used to detect proteins by chemical nose approach based on fluorescence quenching of fluorophore by AuNPs. An array-based sensing platform for detection of six proteins, namely bovine serum albumin, lysozyme, fibrinogen, concanavalin A, hemoglobin, holo-transferrin human can be successfully developed from the PNIPAM-AuNPs having different molecular weights (4 and 8 kDa) and conformation (varied heat treatment from 25 to 40 °C) in combination with a tricationic branched phenylene-ethynylene fluorophore. From principal component analysis (PCA) followed by linear discriminant analysis (LDA), 100% accuracy of protein classification using a leave-one-out (LOO) approach can be achieved by using only two types of PNIPAM-AuNPs.

Cationic‐Polymer‐Functionalized Zinc Oxide Quantum Dots: Preparation and Application to Iron(II) Ion Detection

“…A series of cationic random copolymers p(META‐PEOMEMA) with varying METAC/PEOMEMA molar feed ratios of 100/0, 60/40, and 30/70, were synthesized by RAFT polymerization using 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) as initiator and 4‐cyano‐4‐(phenylcarbonothioylthio) pentanoic acid (CPA) as chain transfer agent (Scheme ). The dithioester group at the polymer chain end can be removed by aminolysis reaction . The structure and actual molar composition ratios of METAC/PEOMEMA in the copolymers, as estimated by 1 H NMR from the ratio of the integral areas of the methylene protons of the METAC units (around 4.40 ppm) compared to the methylene protons of PEOMEMA units (around 4.10 ppm) (Figure S1 and Table S1 in the supporting information), are listed in Table .…”

Recent Progress in Macromolecule‐Anchored Hybrid Gold Nanomaterials for Biomedical Applications

“…Similarly, poly( l ‐lactide) (PLLA) with thiol terminal functionalization could also be closely packed onto AuNP surfaces for nanoparticle surface neutralization to significantly improve their biocompatibility as well as mouse embryonic fibroblasts (NIH3T3) adhesion or proliferation . Furthermore, Kusolkamabot et al prepared AuNPs which were stabilized by grafting thiol‐terminated poly( N ‐isopropylacrylamide) (PNIPAAmSH) onto citrate‐stabilized AuNPs, which constructed a thermosensitive polymeric hybrid AuNP solution with optical detectable red to blue–purple color changes upon temperature increase . Besides nanoparticle form, gold nanorods (AuNRs) could also be surfaced functionalized by disulfide bond–connected poly(ethylene glycol)‐ b ‐poly(ε‐caprolactone) (PEG‐ b ‐PCL) block copolymer, which allowed dense packing of AuNRs with precisely controlled interparticle orientation and exhibited localized surface plasma resonance (LSPR) in the near‐infrared (NIR) region to enhance photothermal therapy (PTT) .…”

PNIPAM grafted surfaces through ATRP and RAFT polymerization: Chemistry and bioadhesion

“…5 [87,88]. The reduction of active chain concentration results in a narrow distribution of the chain length, with a polydispersity index (PDI), for PNIPAM, able to reach values around 1.20, but PDI below 1.10 can be obtained in optimal conditions [89][90][91]. Additionally, RAFT polymerization can be achieved with a broad range of temperatures, from room temperature to 140 • C [92].…”