Gold nanorods coated with a thermo-responsive poly(ethylene glycol)-b-poly(N-vinylcaprolactam) corona as drug delivery systems for remotely near infrared-triggered release

Abstract

5Poly(ethylene glycol)-b-poly(N-vinylcaprolactam) (PEG-b-PNVCL) copolymers are prepared from a PEG macro-chain transfer agent in DMF at 65 °C via reversible addition-fragmentation chain transfer (RAFT) polymerization. Well-defined PEG114-b-PNVCL237 copolymer with a could point temperature of 39 °C is used for the formation of a thermo-responsive polymer corona on the surface of gold nanorods 10 (GNRs) via a "grafting-to" approach. Thermo-responsiveness and thermo-dependent optical properties of the as-obtained GNR@PEG-b-PNVCL nanoparticles are studied with dynamic light scattering and UV/vis spectroscopy techniques. Near infrared (NIR)-induced heating of GNR@PEG-b-PNVCL is also explored in aqueous suspension under NIR laser irradiation (802 nm, up to 250 mW). The potential of these GNR@PEG-b-PNVCL nanoparticles to be used as smart drug delivery systems (DDS) is then 15 studied. A hydrophilic drug model, Rhodamine® B, is used to assess the guest loading capacity, and triggered release behaviours are then evaluated under conventional external heating or internal heating induced by remote NIR irradiation. Cytotoxicity evaluation of the GNR@PEG-b-PNVCL against fibroblast-like L929 cell line is carried out via the MTS assay, in order to confirm the improved biocompatibility of the GNRs after polymer coating. These thermo-responsive GNR@PEG-b-PNVCL 20 nanoparticles are promising DDS that combine the chemotherapeutic and phototherapeutic functions. 115

Poly(N-vinylcaprolactam), a comprehensive review on a thermoresponsive polymer becoming popular

“…Well-defined PEG-b-PNVCL copolymers with different PNVCL block lengths and endcapped by a xanthate group were synthesized via the RAFT technique, but only in the second step of the synthesis [90]. In the first step PEG-MCTA´s were prepared by end-group functionalization of PEG with xanthate.…”

“…Only a few CRP techniques can properly mediate the radical polymerization of NVCL, including reversible additionfragmentation chain transfer (RAFT) [16][17][18][19][88][89][90][91][92][93][94][95], a combination of ring-opening polymerization (ROP) and RAFT [96,97], atom transfer radical polymerization (ATRP) [98], and Cobalt mediated radical polymerization (CMRP) [20,29,66]. Devasia et al [88] reported the first sequential RAFT polymerization to prepare block copolymers of A c c e p t e d M a n u s c r i p t 25 polymerization.…”

The emulsion polymerization induced self-assembly of a thermoresponsive polymer poly(N-vinylcaprolactam)

“…The synthesis of two PEG-based xanthate macro-chain transfer agents (mCTA) with different PEG DP values (42 or 113) was conducted following the literature, 54 with slight modifications. The products are referred to as PEG 42 -X and PEG 113 -X, respectively.…”

“…RAFT polymerization in bulk, were reported in 2008. 21 Following that publication, NVCL has been RAFT/MADIX polymerized by several groups, in bulk, 22,23 in various different organic solvents, [24][25][26][27][28][29][30] and also in water/ ethanol mixtures. 31 NVCL has also been synthesized via ATRP 32,33 and cobalt-mediated polymerization.…”

Gold Nanoparticles for Photothermally Controlled Drug Release

“…Liu et al synthesized AuNRs functionalized with a thermoresponsive corona of poly(ethylene glycol)-bpoly(N-vinylcaprolactam) where internal heating was generated by laser irradiation [51]. This method induced the phase transition of the polymer, liberating the preloaded drug molecule.…”