Coated Chiral Plasmonic Nanorods with Enhanced Structural Stability

Abstract

Several synthesis techniques have emerged for the preparation of chiral metal nanoparticles (NPs) with intrinsic chiral geometrical structures and high optical activity. Chiral plasmonic NPs typically display intricate morphologies terminated by high-energy facets, resulting in limited long-term and thermal stability, which is critical for the development of their applications, e.g., in the biomedical field. Chiral gold nanorods (Au NRs) suffer from loss of structural stability (reshaping), which in turn results in the loss of their optical activity. We carried out a systematic analysis of the stability of chiral Au NRs covered by different protecting shells, against corrosive ions and thermal reshaping. Our findings can be readily extended to other chiral plasmonic NPs with fine structural details and alleviate concerns of instability for various applications under heating and in complex environments.

Multicomponent chiral plasmonic hybrid nanomaterials: recent advances in synthesis and applications

“…An alternative strategy to prepare chiral alloy NRs was developed by Liz-Marzán and co-workers, which built on the use of chiral cosurfactants as templates for the seed-mediated chiral growth of Au NR. [76][77][78] They employed chiral micelles formed by chiral ligands (BINOL, 1,1 ′ -bi(2-naphthol)) and hexadecyl trimethyl ammonium chloride (CTAC) as templates to achieve the co-reduction of Au and Pd/Pt atoms on Au NRs, resulting in the formation of chiral AuPd and AuPt alloy NRs with tunable composition and optical chirality (Fig. 4b).…”

“…4b). [76][77][78] Interestingly, the chirality transfer from chiral molecules to multicomponent alloy materials can be also achieved in a substrate-induced growth procedure, which is signicantly different from that in colloidal solutions with a seed-mediated chiral growth process. 41 Particularly, Che and co-workers employed N-acetyl-L/D-cysteine (S/R-NAC) as a chiral inducer on Si substrates, with HAuCl 4 and AgNO 3 as precursors, to electrochemically generate chiral AuAg bimetallic lms (Fig.…”

Stabilizing Chiral Gold Nanorods from Chiral-Micelle-Directed Synthesis by Sulfide Treatment for Chiroplasmonic Sensing

“…To avoid unwanted weakening of their chiroptical activity, previous research has proposed the encapsulation of chiral Au NRs with mesoporous silicon dioxide or polymers to form core–shell structures . Nevertheless, the encapsulated shells might weaken the sensitivity of Au NRs to the surrounding medium environment, which limits their further utilization in LSPR sensing.…”

“…Both X-ray diffraction (XRD; Figure S10) and inductively coupled plasma mass spectrometry (ICP-MS) indicate that very little sulfur species (approximately 1.5%) exists in sulfide-treated chiral Au NRs, so compared with the construction of a core–shell structure, the method of introducing S 2– ions to the system not only stabilizes the NRs but also makes it more advantageous for surface-sensitive detection sensing applications of chiral Au NRs. Further experiments (Figure S11) have demonstrated the refractive index sensitivity of Na 2 S-treated chiral Au NRs to the surrounding environment.…”

Theoretical Study of Strong Coupling between Molecular Shells and Chiral Plasmons of Gold Nanoparticles Helices

“…The study of light–matter interaction related to chiral molecules or plasmons is an interesting research topic because asymmetric interactions are central to a range of fields such as spectroscopy and photonic devices. − Chirality refers to the property that an object cannot be superimposed with its mirror isomer . Natural chiral isomers have the same chemical formula but can produce different physical phenomena when interacting with different polarized light. − In general, chiral signals of molecules are weak, which limits their optical applications.…”