Thiol-reactive amphiphilic block copolymer for coating gold nanoparticles with neutral and functionable surfaces

Abstract

Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups, such as –COOH and –NH2, to conjugate targeting ligands or drugs. However, introducing highly charged surfaces promotes binding of the nanoparticles to biomolecules in biological systems through ionic interactions, causing the nanoparticles to aggregate in biological environments and consequently undergo strong non-specific binding to off-target cells and tissues. Developing a unique polymer with neutral surfaces that can be further functionalized directly would be critical to develop suitable nanomaterials for nanomedicine. Here, we report a thiol-reactive amphiphilic block copolymer poly(ethylene oxide)-block-poly(pyridyldisulfide ethylmeth acrylate) (PEO-b-PPDSM) for coating gold nanoparticles (AuNPs). The resultant polymer-coated AuNPs have almost neutral surfaces with slightly negative zeta potentials from -10 to 0 mV over a wide pH range from 2 to 12. Although the zeta potential is close to zero we show that the PEO-b-PPDSM copolymer-coated AuNPs have both good stability in various physiological conditions and reduced non-specific adsorption of proteins/biomolecules. Because of the multiple pyridyldisulfide groups on the PPDSM block, these individually dispersed nanocomplexes with an overall hydrodynamic size around 43.8 nm can be directly functionalized via disulfide-thiol exchange chemistry.

Controlled synthesis of gold nanorod dimers with end-to-end configurations

“…This process can be verified by monitoring the extinction peak at 343 nm (ref. 44 ) (see Fig. S1b in ESI † ).…”

Development of Dual‐Pore Coexisting Branched Silica Nanoparticles for Efficient Gene–Chemo Cancer Therapy

“…To prevent the outflow of diffusively loaded Rho 6G into branch domain pore, disulfide bond mediated additional functionalization with 1‐adamatanethiol and following β‐cyclodextrin capping were carried out. To validate the capping on DpSN, first, disulfide bond between thiol group in DpSN and 2‐pyridinethiol was determined by observing the peak of 350 nm induced by 4‐thiopyridine (TPD), because TPD was formed via reaction between thiol group and 2,2′‐dithiodipyridine (DTDP) . The peak of 350 nm was detected in the supernatant of the mixed solution containing DTDP and DpSN, which indicated the disulfide bond formation upon mixing of DTDP with DpSN containing thiol group (Figure S3a, Supporting Information).…”

Pyridyl Disulfide Functionalized Polymers as Nanotherapeutic Platforms

“…Similar to the poly(PDEM‐ co ‐PEG) copolymer scaffold that the Thayumanavan group developed, Sun and coworkers synthesized an amphiphilic block copolymer poly(PDEM‐ b ‐PEG) ( 10 , Scheme ) using same starting materials through RAFT polymerization . The PD functionalized polymer 10 was directly applied to coat gold nanoparticle (AuNP) by simply mixing it with AuNP and stirring them in dimethylformamide.…”