Polymer@gold Nanoparticles Prepared via RAFT Polymerization for Opto-Biodetection

Abstract

Colloidal gold nanoparticles (Au NPs) have been used in several biological applications, which include the exploitation of size-and shape-dependent Localized Surface Plasmon Resonance (LSPR) in biosensing devices. In order to obtain functional and stable Au NPs in a physiological medium, surface modification and functionalization are crucial steps in these endeavors. Reversible addition-fragmentation chain transfer (RAFT) polymerization meets this need offering the possibility of control over the composition and architecture of polymeric shells coating Au NPs. Furthermore, playing with a careful choice of monomers, RAFT polymerization allows the possibility to design a polymer shell with the desired functional groups aiming at Au based nanocomposites suitable for biorecognition and biotargeting. This review provides important aspects concerning the synthesis and optical properties of Au NPs as well as concepts of RAFT polymerization. Understanding these concepts is crucial to appreciate the chemical strategies available towards RAFT-polymer coated Au core-shell nanostructures, which are here reviewed. Finally, examples of applications in opto-biodetection devices are provided and the potential of responsive "smart" nanomaterials based on such structures can be applied to other biological applications.

Characterization of Gold Nanorods Conjugated with Synthetic Glycopolymers Using an Analytical Approach Based on spICP-SFMS and EAF4-MALS

“…Briefly, poly(N-hydroxyethyl acrylamide) (PHEA) was synthesized by photo-initiated RAFT polymerization and modified with galactosamine (Gal) [ 16 ]. RAFT installs sulfur-containing end-groups which have high affinity for gold surfaces [ 32 , 33 , 34 ] and enables installation of a glycan conjugation unit at the opposing end-group [ 35 , 36 ]. The glycopolymers used in this study have two different degrees of polymerization (DP = 35, 60) determined by proton nuclear magnetic resonance analysis in methanol-d4.…”

Azide‐Terminated RAFT Polymers for Biological Applications

“…The R group in these living polymers originates either from the radical initiator or the CTA. For the dead polymers, the number of chains directly correlates to the number of radicals initially introduced in the system by the decomposition of the radical initiator (Pereira, Barros-Timmons, & Trindade, 2018;Perrier, 2017). Therefore, to reduce the percentage of dead polymers within the polymerization products, the feed amount of radical initiator is typically maintained lower than the CTA (Moad, Chong, et al, 2005;Moad, Rizzardo, & Thang, 2009).…”

Engineering Organic/Inorganic Nanohybrids through RAFT Polymerization for Biomedical Applications

“…In contrast, Au NP–N (∼8 kcal mol –1 ) and Au NP–COO– (∼2 kcal mol –1 ) dissociation energies are considerably weaker, comparable in strength to a hydrogen bond, which can easily be displaced, leading to instability as reported in cetyltrimethylammonium bromide (CTAB) modified Au NPs . RAFT has particular utility in preparing polymers for gold stabilization as the RAFT functionality thiocarbonylthio– exhibits a high affinity to Au surfaces and di- and tri-thio CTA agents have been reported for use in the surface modification of Au NPs …”

“…Another example of direct synthesis is the production of Au NPs from tetrachloroauric aciddirectly reduced by reducing agents in the presence of sulfur-terminated polymers . In this system, the polymer chains act as stabilizers for the Au nanoparticles .…”

“…26 RAFT has particular utility in preparing polymers for gold stabilization as the RAFT functionality thiocarbonylthio− exhibits a high affinity to Au surfaces and di-and tri-thio CTA agents have been reported for use in the surface modification of Au NPs. 56 For IONPs, the ligand binding is facilitated by iron-tooxygen interactions. 45 For instance, the carboxylic group (e.g., oleic acid) is often preferred as the surfactant stabilizer during the synthesis of IONPs as it presents a moderate binding affinity and can be subsequently replaced by other higheraffinity anchors.…”