Synthesis and investigation of dual pH‐ and temperature‐responsive behaviour of poly[2‐(dimethylamino)ethyl methacrylate]‐grafted gold nanoparticles

Abstract

Gold nanoparticles (AuNPs) were synthesized by reduction of chloroauric acid (HAuCl4) aqueous solution with hydrazine monohydrate. The AuNPs were immediately treated with cysteamine to obtain amine‐functionalized nanoparticles (Au‐NH2). The reaction of Au‐NH2 with epichlorohydrin and subsequent treatment with sodium hydroxide gave epoxidized AuNPs (Au‐EP). Then, thiol‐capped AuNPs (Au‐SH) were synthesized by reaction of Au‐EP with cysteamine. A ‘grafting to’ approach was utilized to graft bromine‐terminated poly(N,N′‐dimethylaminoethyl methacrylate), synthesized via aqueous atom transfer radical polymerization, with various molecular weights (6280, 25 800, 64 200 and 87 600 g mol−1) onto Au‐SH to obtain Au‐P1, Au‐P2, Au‐P3 and Au‐P4 samples, respectively. All samples were exposed to temperature and pH variations, and Z‐average diameter was monitored using dynamic light scattering. According to the results, polymer‐grafted nanoparticles collapsed at lower temperatures with increasing solution pH for all molecular weight ranges due to deprotonation of tertiary amine groups. However, higher molecular weight polymers were more sensitive to pH variation especially in alkaline media. Also, a high degree of agglomeration was observed for Au‐P4 nanoparticles in alkaline media on increasing the temperature to 55 and 65 °C.

Synthesis and characterization of poly(propylene imine)-dendrimer-grafted gold nanoparticles as nanocarriers of doxorubicin

“…Gold nanoparticles (AuNPs) as non-toxic and biologically compatible nanoparticles have gotten increasing attention in different fields such as biomedicals [1], hybrid nanomaterials [2], etc. Also, Surface Plasmon resonance (SPR) as a unique optical property is conferred by the interaction of light with electrons on the surface of gold nanoparticles [3].…”

N,N'‐methylenebis(acrylamide)‐crosslinked poly(acrylic acid) particles as doxorubicin carriers: A comparison between release behavior of physically loaded drug and conjugated drug via acid‐labile hydrazone linkage

“…). Also, the number‐averaged particle size ( D n ), weight‐averaged particle size ( D w ), and polydispersity index (PDI) are calculated according to the following equations: where n i and D i are the number of particles and diameter respectively. According to the results, D n is 234.1, 167.7, and 267.0 nm for P1, P2, and P3, respectively.…”

Multi-stimuli-responsive aggregation of nanoparticles driven by the manipulation of colloidal stability

“…72 However, there are limitations to this, as Mohammadi et al found a low mole-cular weight PDMAEMA brush layer (M n = 6280 g mol −1 ) could not exhibit temperature-responsive behaviour, regardless of pH. 74 It is important to note that there are many examples of other homopolymer stabilized NP systems that are likely to aggregate in response to pH and temperature changes, however, many publications focus on the stabilization of these systems.…”