Triggering nanoparticle surface ligand rearrangement via external stimuli: light-based actuation of biointerfaces

Abstract

Bio-molecular non-covalent interactions provide a powerful platform for material-specific self-organization in aqueous media. Here, we introduce a strategy that integrates a synthetic optically-responsive motif with a materials-binding peptide to enable remote actuation. Specifically, we linked a photoswitchable azobenzene moiety to either terminus of a Au-binding peptide. We employed these hybrid molecules as capping agents for synthesis of Au nanoparticles. Integrated experiments and molecular simulations showed that the hybrid molecules maintained both of their functions, i.e. binding to Au and optically-triggered reconfiguration. The azobenzene unit was optically switched reversibly between trans and cis states while adsorbed on the particle surface. Upon switching, the conformation of the peptide component of the molecule also changed. This highlights the interplay between the surface adsorption and conformational switching that will be pivotal to the creation of actuatable nanoparticle bio-interfaces, and paves the way toward multifunctional peptide hybrids that can produce stimuli responsive nanoassemblies.

Optical Actuation of Inorganic/Organic Interfaces: Comparing Peptide-Azobenzene Ligand Reconfiguration on Gold and Silver Nanoparticles

“…In a very recent study, we demonstrated that covalent attachment of an optically-responsive azobenzene moiety to a specific Au-binding peptide (WAGAKRLVLRRE, denoted AuBP1) preserved the optical switching response of the azobenzene, both in solution and when the hybrid biomolecule was adsorbed onto Au NPs. 26 In the adsorbed state, we found that the ratio of the forward and reverse switching rates of the azobenene unit were inverted compared with the ratio for the hybrid molecule free in solution. This indicated that the interaction between the azobenzene and the Au surface influenced the photoswitching kinetics.…”

“…benzamide) (MAM). The MAM molecule was prepared as described in our previous study 26 and in the Supporting Information. Briefly, azobenzene-4,4'-dicarboxylic acid (2.67 g, 9.9 mmol) and thionyl chloride (60 mL) were refluxed overnight to obtain azobenzene-4,4'-dicarboxylic acid chloride, which was then dissolved in methylene chloride (10 mL) and mixed with a solution of N- (2-aminoethyl)maleimide hydrochloride (620 mg, 3.5 mmol) and triethylamine (TEA, 0.7 mL) in methylene chloride (10 mL).…”

Halo-substituted azobenzenes adsorbed at Ag(111) and Au(111) interfaces: Structures and optical properties

“…Incorporation of AB into a larger biomolecular structure offers opportunities to control specific biological targets in vivo, allowing optically-controlled drug release, 7,8 as well as in the field of bionanocombinatorics, where biomolecular non-covalent recognition can be used to assemble ordered nanostructures capable of reconfiguration. [9][10][11][12] Given that many of these applications involve the interface of the photoswitch in contact with a solid surface, elucidation of the structure and properties of AB and its derivatives, adsorbed at material interfaces, is much needed.…”

Non-covalent adsorption of amino acid analogues on noble-metal nanoparticles: influence of edges and vertices

“…22 Recent exploitation of non-covalent metalbiomolecule interactions in this area has included the use of peptides as agents to realise the in-situ nucleation, growth, dispersion, and catalytic activation of NMNPs in aqueous solution. [9][10][11][12][13][14][15] Moreover, the direct non-covalent adsorption of nucleic acid aptamers onto unfunctionalised NMNPs is a key component of successful biomolecular sensor design (see Martin et al 5 for a recent example).…”

“…[6][7][8] Moreover, the ability to predictably manipulate the growth morphology of noble metal nanoparticles (NMNPs) in aqueous media via additive-based strategies, especially to produce nonspherical Au NP morphologies, is integral to exerting fine control over NP size and shape. [9][10][11][12][13][14][15] Knowing how and where these additives prefer to bind at the NP interface is key to realizing these strategies 16 .…”