Light-Switchable Self-Assembly of Non-Photoresponsive Gold Nanoparticles

Abstract

Herein, an interesting light-induced self-assembly behavior from non-photoresponsive gold nanoparticles (Au NPs) was reported. Specifically, a pH-responsive amphiphile SPBwas developed that contained a particular phenylboronic acid moiety and showed excellent surface activity at the neutral and basic conditions, thereby stabilizing Au NPs well. Accordingly, the SPB-functionalized Au NPs showed strong pH dependence that there presented the pH-induced reversible self-assembly behavior. Furthermore, the introduction of a small amount of commercially available photoacid generator named diphenyliodonium nitrate (DIN) into the system could endow it with apparent light-switchable self-assembly behavior. The pH- and light-induced self-assembly behaviors of SPB-functionalized Au NPs in the absence and presence of DIN, respectively, were systematically studied by various techniques including UV-vis spectrum, transmission electron microscope, nuclear magnetic resonance, and Fourier transform infrared spectroscopy, which evidently confirmed that the stimuli-responsive self-assembly was controlled by the hydrogen-bonding interactions between phenylboronic acid moieties. Attributing to the light-induced obvious color change from bright-red to deep purple, the system was applied in particle imprinting successfully.

Photoresponsive Photoacid-Macroion Nano-Assemblies

“…It also bears great synthetic potential for the formation of versatile, switchable, and functional nanostructures [ 2 , 3 , 4 , 5 ]. Noncovalent interactions can be triggered by external influences, such as the change of pH [ 6 , 7 , 8 , 9 ], light irradiation [ 10 , 11 , 12 , 13 , 14 ], thermal activation [ 15 , 16 , 17 , 18 ], introduction of a magnetic field [ 19 , 20 , 21 ], moisture, or redox response [ 22 , 23 , 24 , 25 ]. Of high interest are light-responsive systems, for example in the fields of sensors [ 26 , 27 , 28 ] or therapy [ 29 , 30 , 31 ], and, thus, it is desirable to explore novel concepts toward light-triggerable self-assembly.…”

Adaptive Nanoparticle‐Polymer Complexes as Optical Elements: Design and Application in Nanophotonics and Nanomedicine

“…The developed NP-polymer complexes demonstrated pH-induced reversible self-assembly behavior, however, the introduction of photo-acid generator (diphenyliodonium) changed self-assembly behavior induced by light. [164] An external electric field can maintain the assembled state of the NP-polymer complexes. Montelango et al reported on the implementation of electrotunable liquid mirror based on voltage-controlled self-assembly of mercaptopropanesulfonate-stabilized 16 nm Au NPs at the interface between two immiscible electrolytes.…”

“…The developed NP‐polymer complexes demonstrated pH‐induced reversible self‐assembly behavior, however, the introduction of photo‐acid generator (diphenyliodonium) changed self‐assembly behavior induced by light. [ 164 ] An external electric field can maintain the assembled state of the NP‐polymer complexes. Montelango et al.…”

The Many Ways to Assemble Nanoparticles Using Light

“…In Section , we discussed examples of the reversible self‐assembly of non‐photoswitchable NPs in light‐responsive media. Li and co‐workers designed a light‐responsive medium capable of decreasing the pH irreversibly, thus inducing the formation of permanent NP aggregates . For the photosensitive component of the light‐responsive medium, these researchers used a solution of a commercially available, water‐soluble photoacid generator, diphenyliodonium nitrate.…”