# Tunable Plasmonic Circular Dichroism of Hierarchical Chiral Assemblies

Jaime Gabriel Trazo, Andrés Serrano Freijeiro, Mikhail Mychinko, Nika Kutalia, Marianne Impéror-Clerc, Sara Bals, Luis Liz-Marzán, Jorge Pérez-Juste, Isabel Pastoriza-Santos, Cyrille Hamon

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Jaime Gabriel Trazo, Andrés Serrano Freijeiro, Mikhail Mychinko, Nika Kutalia, Marianne Impéror-Clerc, et al.. Tunable Plasmonic Circular Dichroism of Hierarchical Chiral Assemblies. Chemistry of Materials, 2025, 16 (21), pp.9320-9325. 10.1021/acs.chemmater.5c00909. [hal-05217679](https://hal.science/hal-05217679v1)

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Submitted on 21 Aug 2025

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Distributed under a Creative Commons Attribution 4.0 International License
Tunable Plasmonic Circular Dichroism of Hierarchical Chiral
Assemblies

Jaime Gabriel Trazo,¹§ Andrés Serrano Freijeiro,²§ Mikhail Mychinko,³ Nika Kutalia,¹ Marianne Impéror-Clerc,¹ Sara Bals,³ Luis M. Liz-Marzán,²,⁴,⁵,⁶ Jorge Pérez-Juste,²* Isabel Pastoriza Santos,²* and Cyrille Hamon¹*

¹ Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, Orsay 91405, France.

² CINBIO, Universidade de Vigo, Departamento de Química Física, Campus Universitario As Lagoas, Marcosende, Vigo 36310, Spain

³ EMAT and NANOlab Center of Excellence, University of Antwerp, 2020 Antwerp, Belgium.

⁴ CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), 20014 Donostia-San Sebastián, Spain;

⁵ Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBERBBN), 20014 Donostia-San Sebastián, Spain;

⁶ Ikerbasque, Basque Foundation for Science, 48009 Bilbao, Spain;

⁷ J.G.T and A.S.F contributed equally to this paper

* Corresponding authors

Jorge Pérez-Juste: juste@uvigo.gal

Isabel Pastoriza Santos : pastoriza@uvigo.gal

Cyrille Hamon : cyrille.hamon@cnrs.fr
**Abstract**

Plasmonic circular dichroism (PCD) is a powerful approach for enhancing chiroptical effects at the nanoscale, with promising applications such as optical information processing, sensing, and catalysis. However, a key challenge remains in achieving both strong and tunable chiral optical responses. While most strategies use either intrinsically chiral nanoparticles (NPs) or achiral NPs arranged into chiral assemblies, combining both offers a promising route to amplify chiral optical responses. Here, fourfold-twisted gold nanorods (cGNRs) were assembled by depletion-induced self-assembly (DISA) into chiral superstructures with tunable PCD properties. By reducing cGNR helicity via chemical etching, we study how building block helicity affects hierarchical structure formation. Whereas static helical supercrystals were obtained on substrates upon evaporation-induced self-assembly (EISA), DISA allowed us to dynamically modulate the interparticle distance in solution from 13 ± 1.2 nm to 6.9 ± 1.0 nm. The assembly/disassembly process was found to be fully reversible, thereby enabling a modulation of the g-factor by two orders of magnitude with a switching rate of approximately 1 hour. Beyond achieving high dissymmetry factors of 0.2, our approach establishes a reconfigurable PCD platform that is free from ligand exchange constraints and compatible with different NP shapes. Though response times remain too slow for optical computing, these findings are relevant for the development of optical modulators and memory devices based on dynamic chiral metafluids.
Introduction

Plasmonic circular dichroism (PCD) is emerging as a powerful tool for amplifying chiroptical effects at the nanoscale, which can be driven by various mechanisms. ¹⁻⁴ Here, we focus on a combination of optical activity arising from geometrical chirality, which can be observed in colloidal nanoparticles (NPs) lacking mirror and inversion symmetry, with the assembly of colloidal NPs into chiral superstructures. Colloidal PCD materials enable energy selective, dissymmetric interactions with circularly polarized light, opening potential applications in chiral sensing, enantioselective catalysis and optical information processing. ⁵⁻¹¹ Various synthetic protocols have been developed to produce chiral plasmonic NPs, often involving chiral molecules or micelles, ¹², ¹³ while also different strategies have been employed for the assembly of achiral NPs into chiral structures. ¹⁴⁻¹⁷ Although these two approaches have evolved independently, a few recent studies propose combining them to obtain materials with high and tunable dissymmetry factors. ¹⁸⁻²² Some of these recent works have focused on assembling chiral NPs into achiral structures to induce a tunable PCD response, but no significant increase in the PCD amplitude was reported. Instead, different outcomes were observed: either a loss of the PCD response²⁰ or a spectral shift in the PCD signal due to plasmonic coupling. ²¹, ²² PCD enhancement appears to depend critically on hierarchical chirality, as shown in another work, ¹⁸ where the assembly of four-fold twisted chiral gold nanorods (cGNRs) into helical superstructures led to enhanced PCD compared to individual cGNRs. ¹⁸ In the latter work, the assembly process was driven by the irreversible aggregation of colloids upon electrostatic screening. We hypothesized that introducing depletion forces in such systems would offer a greater versatility in tuning the interactions between cGNRs, thereby enabling active control over the PCD response.

Depletion-induced self-assembly (DISA) is driven by an entropic attraction between colloids upon introduction of smaller particles, as bringing the colloids closer together increases the free volume available to the depletants (typically polymers or surfactant micelles). ²³⁻²⁶ The range of accessible interparticle distances is given by the size of depletant, whereas the strength of the interaction increases with the osmotic pressure, hence with the depletant concentration. ²⁶ In the plasmonic NP field, DISA has been primarily used for shape purification and for the formation of assemblies on substrates, in conjunction with evaporation-induced self-assembly (EISA). Recent works has demonstrated that DISA can be used for the reversible assembly of plasmonic NPs in suspension into well-defined structures with tunable lattice parameters. ²⁵, ²⁷⁻²⁹ In this process, there is no need for ligand exchange because the same surfactant used during NP
synthesis can also be used for DISA, where the micelles serve as effective depletants. Although
various anisotropic NP shapes have been successfully assembled using DISA, the self-assembly
of chiral NPs through this method remains unexplored.

Reconfigurable PCD materials offer a precise control over spectral and dynamic aspects of the PCD response, which is essential for developing responsive chiral nanodevices.<sup>30,31</sup> While PCD can be manipulated by applying external stimuli (e.g., chemical, electrical, mechanical, or electromagnetic) to NPs attached onto a substrate,<sup>31</sup> their structural conformation remains largely unchanged. In contrast, chiral assemblies dispersed in solution offer a promising alternative, because colloids can be assembled, disassembled, and rearranged into tailored structures to modulate the PCD response. Beyond being fundamentally different from substrate-based strategies, such “metafluids” are isotropic, thereby avoiding the dependence of excitation incidence, and their ability to reconfigure in volume can be advantageous for chiral sensing and catalysis, by facilitating interactions between target molecules and NPs. Typically, existing reconfigurable systems rely on soft matter templates, like liquid crystals or DNA origami, to control the orientation of achiral plasmonic NPs.<sup>31-35</sup> However, these template-based approaches impose limitations on versatility and scalability, requiring processing steps such as ligand exchange and template design, which constrain NP shape, size, and achievable assemblies. Moreover, the assembly of chiral NPs into higher-order chiral nanostructures is yet to be demonstrated by these methods. In contrast, DISA offers a template-free approach that can simply consist of modulating the concentration of the surfactant used during NP synthesis to drive their assembly. Here, we show that DISA can be used to assemble higher-order chiral structures with dynamically tunable chiroptical properties. This represents a significant step toward the creation of active chiral fluids capable of controlling light’s amplitude, frequency, and polarization in real time.

We report the reconfigurable assembly of cGNRs into hierarchical chiral structures. We synthesized cGNRs and controlled their helicity through precise chemical etching, resulting in nanostructures with varying lattice symmetries. Using EISA with the same cGNRs, we obtained supercrystals with a helical structure, whereas DISA allowed for tunable inter-NP distances by adjusting the depletant concentration, ranging from 13 nm to 7 nm. The g-factor of the assembled cGNRs was enhanced by two orders of magnitude compared to the isolated cGNRs measuring at the same wavelength, reaching these assemblies a highest value around 0.2. Furthermore, the PCD response could be dynamically adjusted in solution by cGNR assembly
and disassembly. This work demonstrates that DISA enables the formation of template-free,
reconfigurable chiral materials with tunable chiroptical properties.

**Results and discussion**

Fourfold-twisted of cGNRs were synthesized by seeded growth on achiral single-crystalline
GNR seeds, in the presence of a molecular chiral inducer – namely *L*-cysteine.³⁶ To
systematically adjust the helicity of the resulting cGNRs, controlled chemical etching was
performed by using Au³⁺ as an oxidant, which resulted in a gradual transformation of the twisted
cGNRs into achiral nanorods with rounded edges (**Figure 1a**). Our study focused on three GNR
batches: as synthesized chiral nanorods (cGNR_1), partially-oxidized nanorods (cGNR_2)
obtained by etching during 3 hours, and fully oxidized nanorods (cGNR_3) obtained by
extended etching for 24 hours. The dimensions of the resulting nanoparticles, determined by
transmission electron microscopy (TEM), in terms of length (L) and width (W) were as follows:
cGNR_1 (L = 113.8 ± 11.3 nm, W = 59.1 ± 4.4 nm); cGNR_2 (L = 104.2 ± 10.0 nm, W = 54.9
± 3.4 nm); cGNR_3 (L = 89.5 ± 9.9 nm, W = 60.6 ± 2.9 nm) (**Figure S1**). Representative
cGNRs from each sample were investigated by electron tomography (ET), and the 3D
reconstructions evidenced that the degree of twisting decreased in the order cGNR_1 > cGNR_2
> cGNR_3 (**Figure 1b**). This trend was confirmed by quantitative analysis of the twisted
morphology through computation of the helicity function H(ρ,α) from the 3D reconstructions
as recently reported (**Figure 1c**, see SI for details on the quantification).³⁷ Indeed, total helicity
values H<sub>tot</sub> of 0.065, 0.045, and 0.018 were determined for cGNRs obtained at increasing
etching times. The positive sign of the helicity measure indicates a right-handedness of the
nanorods, as expected from seed mediated growth in the presence of *L*-cysteine. As etching
progressed, a blue-shift of the longitudinal plasmon band was observed (**Figure 1d**), along with
a reduction in circular dichroism (**Figure 1e**), indicating the loss of plasmonic chirality due to
cGNR etching.
<figure><img src="image_2.png" /><figcaption>**Figure 1:** Reducing the helicity of twisted gold nanorods by controlled etching. (a) Scheme of the etching process to gradually reduce the helicity of cGNRs. (b) Electron tomography reconstructions of cGNRs with decreasing helicity. Scale bar is 50 nm for all images. (c) Corresponding plots of the helicity function $H(\rho, \alpha)$ for each cGNR. (d-e) Extinction and g-factor spectra, respectively, for the different cGNR samples.</figcaption></figure>

All three cGNR colloids were then self-assembled by using two methods, EISA on a substrate and DISA in solution. For the dried assemblies, the resulting nanostructures were analyzed via in-situ small angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) (Figure 2).
<figure><img src="image_3.png" /><figcaption>**Figure 2:** Self-assembly of cGNRs with varying helicity into supercrystals. (a) Photograph of a sessile droplet containing cGNR_1 before (left) and after (right) drying on a silicon substrate. (b) SEM micrographs at low magnification, corresponding to cGNR_1 (black), cGNR_2 (red) and cGNR_3 (blue) supercrystals. (c) SAXS-integrated diffractograms collected on dry supercrystals for cGNR_1 (black), cGNR_2 (red) and cGNR_3 (blue) and corresponding indexation for a 2D rectangular lattice (top) and a 3D hexagonal lattice (bottom). (d) SEM micrographs high magnification, corresponding to cGNR_1 (black), cGNR_2 (red) and cGNR_3 (blue) supercrystals.</figcaption></figure>

We studied first the self-assembly of cGNRs into supercrystals by EISA. A droplet of each cGNRs sample in 2.5 mM cetyltrimethylammonium chloride (CTAC) solution was allowed to evaporate slowly on a silicon substrate (Figure 2a). Upon complete drying, supercrystals with semi-elliptical shapes and of varying sizes were analyzed by SEM (Figure 2b,d and S4-S6). The average size of the supercrystals increased as the helicity of the rods decreased, ranging from 5.3 ± 2.5 µm² for cGNR_1, to 38.1 ± 14.4 µm² for cGNR_2, and 30.3 ± 10.7 µm² for cGNR_3 (Figure S2). These results suggest that the packing frustration for cGNR_1 is more likely to introduce lattice defects than cGNR_3, which in turn causes the supercrystals to break at smaller sizes. For complementary structural analysis, we collected 2D SAXS images and processed the data to generate the integrated diffractograms shown in Figure 2c. In SAXS, the beam footprint measured approximately 175 × 300 µm², significantly larger than a single
supercrystal. As a result, each measurement represents an average over multiple supercrystals, providing a broader structural overview that complements the local observations obtained through SEM. For both cGNR_1 and cGNR_2, SEM micrographs revealed a layered helical structure (Figure 2d), which was indexed as a rectangular centered (rhombic) lattice by SAXS (Figure 2c). This structure consists of stacked twisted layers of cGNRs, where each individual layer has a centered rectangular lattice. On the other hand, a hexagonal lattice structure was identified for cGNR_3 (Figure 2c). We also collected SAXS diffractograms at different positions on the sample, as the structure could vary between the edge and the center due to the coffee ring effect (Figure S3).38-40 While the structure of cGNR_2 supercrystals remained consistent across the substrate, cGNR_1 supercrystals were more extended at the edges of the deposit. Additionally, the orientation of cGNR_3 gradually shifted from horizontal (long axis parallel to the substrate) at the edges to vertical (long axis perpendicular to the substrate) toward the center. Variation in nanorod orientation across the sample and semi-elliptical supercrystal shapes have been observed across a range of nanorod systems with differing shapes and surface chemistries,41-43 suggesting that the underlying mechanism is independent of these specific parameters. While the coffee-ring effect is known to generate gradients in NP and surfactant concentrations during evaporation,38, 40 the precise role of these gradients in directing the formation and symmetry of supercrystals is not yet fully understood. Further studies are required to disentangle the contributions of evaporation dynamics, interparticle forces, and interfacial effects to the final superstructure morphology. Overall, our experiments demonstrate that supercrystals with hierarchical chirality can be achieved through EISA for building blocks with geometrical helicity. However, since the structures are dried, they are non-reconfigurable.

Our second approach involved the self-assembly of cGNRs in solution through DISA.26, 29 As CTAC micelles act as effective depletants, the cGNRs were exposed to various CTAC concentrations to induce the formation of colloidal assemblies (Figure 3a).
<figure><img src="image_4.png" /><figcaption>**Figure 3: cGNRs assembled by DISA in solution.** (a) Photograph of five cuvettes containing $cGNR_1$ at 2 mM, 61 mM, 81 mM, 201 mM, and 505 mM CTAC concentrations, from left to right. (b) SAXS-integrated diffractograms collected in solution for $cGNR_1$ at the same CTAC concentrations. (c) Schematic illustrating how variations in CTAC concentration modulate inter-NP distance. (d) Plot of inter-NP gap distance (face-to-face) as a function of CTAC concentration.</figcaption></figure>

At 2.5 mM CTAC, the SAXS curves correspond to the form factor of non-interacting isolated NPs, indicating stable dispersions (Figure 3b). At CTAC concentration above 60 mM, Bragg peaks emerge, indicating the formation of colloidal cGNR assemblies. The peak indexation revealed different structures depending on nanorod helicity. The $cGNR_1$ sample exhibited a 1:2:3:4 peak progression, corresponding to the formation of one-dimensional (1D) nanostructures with an internal side-by-side nanorod alignment (Figure 3b). In comparison, $cGNR_2$ and $cGNR_3$ assemble in solution into 2D nanostructures, consistent with their EISA counterpart. While $cGNR_2$ assemble into 2D centered rectangular lattices (Figure S7a), $cGNR_3$ lattice is hexagonal (Figure S7b). Debye-Scherrer analysis$^{44}$ revealed that the extension of the lattices was consistently smaller for $cGNR_1$, compared to $cGNR_3$ (Figure S8). These trends align with the size analysis EISA obtained supercrystals (Figure S2), yet the
smaller size of assemblies formed in solution compared to those formed upon drying suggests that the slow drying process promotes the development of higher-order structures. Although lattice symmetries were similar between EISA and DISA samples, the inter-NP gap distances differed significantly between both strategies. The inter-NP distance averaged 2.6 ± 0.9 nm in the EISA samples, whereas it ranged from 13.2 ± 1.2 nm to 6.9 ± 1.0 nm in DISA for cGNR_1 as CTAC concentration in the colloidal dispersion was varied (Figure 3c-d). This shifting equilibrium distance results from the balance between attractive forces (depletion and van der Waals) and repulsive electrostatic interactions.²⁷ Around 500 mM in CTAC, the inter-NP spacing approaches the thickness of the two surfactant bilayers coating adjacent cGNRs (≈ 6.4 nm).⁴⁵ Overall, SAXS experiments indicate that the assemblies of cGNRs formed by DISA corresponds to the helical assemblies formed by EISA in terms of lattice symmetry (but not inter-NP distance). To complement SAXS results, we carried out liquid-phase TEM (LPTEM) and cryo-TEM to image the assemblies of cGNR_1 in the direct space (Figure S9-S10). In both case, side to side arrangement was evidenced, supporting the formation of 1D nanostructures in solution. This set of experiment allowed us to confirm a larger inter-NP distance for assemblies obtained via DISA, compared to EISA, with approximately 10 nm observed in solution (Figure S10), versus 2.5 nm in the dried state, in good agreement with SAXS diffractograms. Although LPTEM and cryo-TEM confirmed the presence of large interparticle distances, they did not allow us to estimate the twist angles. This limitation stems from the tendency of such assemblies to reorganize, especially in confined environments where NPs align with interfaces. We have previously studied this effect and demonstrated that assemblies formed via DISA can undergo rearrangement before and during TEM observation, mainly due to radiolysis effects.⁴⁶

We now turn our focus on the PCD response of the colloidal assemblies mediated by DISA (Figure 4a). As a control experiment, tests were conducted at a low CTAC concentration (10 mM), where no assemblies were observed, so both extinction and CD spectra remained unaltered (Figure 4b).
<figure><img src="image_5.png" /><figcaption>**Figure 4: Reconfigurable PCD assembly of cGNR_1 via DISA.** (a) Photograph of three cuvettes containing, from left to right: cGNR_1 in 1 mM CTAC; cGNR_1 in 70 mM CTAC after 30 minutes of sedimentation; and cGNR_1 in 70 mM CTAC after redispersion of the precipitate. (b-d) Self-assembly kinetics of cGNR_1 in 10 mM (b) and 70 mM (c) CTAC monitored by extinction (top) and CD (bottom) spectroscopies. (d) Extinction (top) and CD (bottom) spectra of cGNR_1 dispersion in 70 mM CTAC recorded at different times. Before optical measurements, the colloidal dispersion was manually shaken. (e) Maximum CD response as a function of CTAC concentration. (f) Reconfigurable g-factor, calculated at 740 nm, as a function of CTAC concentration cycles. Schemes illustrating the concept of reconfigurable PCD response.</figcaption></figure>
At CTAC concentration above 50 mM, DISA induced significant enhancement of the chiroptical response of the cGNR suspensions (Figure 4c and Figure S11). Kinetic experiments were conducted by monitoring the CD signal throughout the self-assembly process. As shown in Figure 4c for 70 mM CTAC, assemblies formed rapidly within 30 seconds and continued to grow over the following 30 minutes. Kinetic SAXS experiments confirmed that the assemblies formed within 2 minutes (Figure S12). At the earlier stages of DISA, enhanced CD responses compared to individual cGNRs were recorded, together with a reversal of the bisignate peak of the assemblies compared to the individual NPs (Figure 4c and Figure S11). For instance, the cGNR_1 assemblies achieved an optical asymmetry g-factor of 0.2 at 740 nm which was two orders of magnitude higher than that of individual c-GNRs (0.0016 at the same wavelength). We infer that chiral amplification may arise from the formation of clusters rather than requiring extended order,¹⁸ as supported by SAXS experiments. Moreover, the inversion in chirality can be attributed to a gain in compactness when the cGNRs of a given helicity self-assemble into structures with opposite handedness.¹⁸ At later stages of the DISA process, the CD signal red-shifted and decreased in amplitude, likely due to the formation of larger assemblies that sedimented at the bottom of the cuvette (Figure 4a). Similar results were obtained for CTAC concentrations ranging from 50 to 756 mM (Figure S11). It should be noted that the decrease in CD signal at CTAC concentrations above 100 mM is due to the extremely fast depletion and sedimentation of the particles, which does not allow for a reliable measurement of the CD response of the assembly. Interestingly, at any stage of the process, the assemblies sedimented in the cuvette could be redispersed restoring a CD signal close to its initial maximum value, even after 10 hours (Figure 4d). Analyzing the extinction and CD band during the self-assembly revealed a gradual red shift due to plasmonic coupling between neighboring NPs (Figure 4c and Figure S11).⁴⁷ Since, side-to-side NP coupling would result in a blue shift of the resonance modes,¹⁸ the red shift here suggests the formation of self-assemblies with multiple coupling modes, including both side-to-side and end-to-end interactions. Interestingly, plotting the maximum CD as a function of CTAC concentration revealed a maximum when particles were dispersed in 90-200 mM CTAC (Figure 4e, Figure S11).

From the SAXS analysis, we can conclude that the overall size of the assemblies did not change significantly with the added CTAC concentration (Figure S13), counting 3-4 cGNRs per assembly and with inter-NP distances varying between 10.9 ± 1.2 nm and 8.9 ± 1.1 nm within the 90-200 mM CTAC range. Therefore, the variation of the CD response with CTAC
concentration could be ascribed to the assembly of cGNRs. Similar experiments were carried
out with cGNR_2 and cGNR_3 at 70 mM CTAC. As shown in **Figure S14**, self-assembly led
to an enhanced CD signal for cGNR_2, whereas the increment was lower than for cGNR_1. In
contrast, no significant CD response was detected for cGNR_3. LPTEM and Cryo-TEM
analyses of the assemblies confirmed the presence of a ladder-type assembly with relatively
large interparticle distances (see **Figures S9-S10**) but, unfortunately, these techniques did not
allow us to obtain a reliable estimate of the twist angle. Recently, Liu et al. reported finite
difference time domain (FDTD) simulations for assemblies comprising cGNRs with a similar
morphology to those presented in our study.¹⁸ The authors studied in detail the effect of the
number of particles forming the assembly, the gap distance between particles, and the rotation
angle between adjacent particles. The results indicate a highest CD signal for assemblies
containing 3-5 chiral nanorods, with gap distances of 3-6 nm and rotation angles between 20°
and 30° (see Figure 4 in ref. 18). Interestingly, the reported FDTD simulations are in good
agreement with our experimental spectra. Therefore, even though the limitations of the DISA
approach do not allow an *in situ* determination of the rotation angle, we propose that the FDTD
simulations reported in reference 18 sufficiently explain our experimental data.

We then leveraged the tunability of depletion interactions to actively adjust the PCD response of these assemblies. Initially, cGNR_1 was self-assembled via DISA at 70 mM CTAC, and the resulting sediment was subsequently redispersed in a 1 mM CTAC solution inside the same cuvette (**Figure 4f and Figure S15**). This cycle was repeated multiple times, leading to reversible *g*-factor variations spanning two orders of magnitude (from 0.0016 to 0.2 measured at 740 nm) as the system switched between disassembled and assembled states. Notably, at higher wavelengths (e.g. 880 nm), the dispersed cGNRs almost do not display chiroptical activity (*g*-factor around 0.001) whereas the assemblies display a high *g*-factor of 0.1. This demonstrates that integrating chirality across different length scales is a promising strategy for designing materials with strong chiroptical properties over a broad spectral range. Additionally, our approach enables modulation of the *g*-factor in solution, achieving a two-orders-of-magnitude change with a switching rate of approximately one hour, which can be accelerated by centrifugation for five minutes at 2240 rcf.

Conclusions

This work demonstrates that cGNRs can be assembled into hierarchical chiral nanostructures
via DISA, exhibiting enhanced, spectrally tunable, and temporally dynamic PCD responses.
Gold nanorods with a gradual degree of helicity were obtained by colloidal synthesis combined
with chemical etching, allowing us to investigate how the chirality of the building blocks
influences the construction of higher order chiral structures by self-assembly. Different
hierarchical structures, ranging from smectic to centered rectangular, were obtained by EISA,
notably forming extended helical supercrystals on substrates. In solution, the cGNRs can be
reversibly assembled by DISA, resulting in a wide tunability of the PCD response. In these
experiments, the inter-NP gap distance could be tuned from 13 ± 1.2 nm to 6.9 ± 1.0 nm by
adjusting CTAC concentration. The reversible process of assembling and disassembling the
NPs could be repeated multiple times inside the same cuvette, leading to variations of the g-
factor by two orders of magnitude when switching between the disassembled and assembled
states. This work shows that DISA can be used to form nanostructures with hierarchical
chirality displaying enhanced, spectrally tunable and temporally evolving PCD responses.
Besides achieving a remarkably high g-factor, we demonstrate reconfigurable PCD response
with a switching rate of about 1 hour. While these rates are still too slow for display
technologies or optical computing,⁴⁸,⁴⁹ they open new possibilities for optical modulators and
memory devices. Overall, DISA offers a novel pathway to achieve hierarchical chirality in
plasmonic NPs, with the added advantage over purely electrostatic strategies of greater
versatility, enabling reconfigurability and tunable optical responses.

**Experimental section**

*Chemicals*. All of the starting materials were obtained from Sigma-Aldrich and used without further purification: hexadecyltrimethylammonium bromide (CTAB for molecular biology ≥99%), hexadecyltrimethylammonium chloride (CTAC, 95% w/w aqueous solution), 1-decanol (n-decanol, 98%), hydrogen tetrachloroaurate trihydrate (HAuCl₄·3H₂O, ≥ 99.9%), silver nitrate (AgNO₃, ≥ 99.0%), L-ascorbic acid (≥99%), Hydroquinone (HQ, ≥99%) sodium borohydride (NaBH₄, 99%), D-cysteine (D-cys, 99%), and L-cysteine (L-cys, 99%). Milli-Qgrade water (resistivity 18.2 MΩ cm at 25 °C) was used in all experiments. All reagents were used as received without further purification.

*Characterization.* TEM and low-magnification TEM images were obtained on a JEOL JEM-1400PLUS transmission electron microscope operating at an acceleration voltage of 120 kV. For UV-vis-NIR spectroscopy, extinction spectra were recorded using Jasco V-750 spectrophotometer. Regarding circular dichroism spectroscopy, spectra were recorded using a Jasco V-1700 CD-spectrophotometer. For the characterization of colloidal dispersions, quartz cuvettes with an optical path of 5mm were used for the extinction and CD equipment. Au⁰
concentrations of the cGNR suspensions were estimated using their measured extinction at 400 nm, taking a NP concentration of 0.5 mM in Au⁰ for a sample absorbance of 1.2.⁵⁰

*Synthesis of cGNRs:* cGNRs were prepared by a five-steps seed mediated growth approach that can be described as followed: (1) the synthesis of 1-2 nm gold seeds, (2) synthesis of small anisotropic seeds, (3) synthesis of “minirods”, (4) synthesis of larger achiral rods, (5) synthesis of the cGNRs. Steps 1-4 were adapted from González-Rubio et al.⁵¹ with minor modifications and step 5 was described in Bing Ni et. al.³⁶ with slight modifications.

1) *Synthesis of 1-2 nm gold seeds:* In a 50 mL glass baker, 50 µL of NaOH 0.5 M was added to 20 mL of an aqueous solution containing 50 mM CTAB and 13.5 mM n-decanol at 27 °C to adjust the pH to 7.6. Then, 200 µL of a 50 mM HAuCl₄ solution was added, obtaining a yellowish solution. Immediately after, 800 µL of fresh 20 mM NaBH₄ was added under strong magnetic stirring (1000-1100 rpm). The reduction was allowed to proceed under stirring for 2 min until the solution turned brownish yellow. The solution was then left undisturbed for at least 1 h at 27 °C prior to use.

2) *Synthesis of anisotropic seeds:* In a 500 mL Erlenmeyer flask, 200 mL of an aqueous solution containing 50 mM CTAB and 13.5 mM n-decanol at 27 °C was prepared. Subsequently, 1.6 mL of 10 mM AgNO₃, 14 mL of 1 M HCl, 2 mL of 50 mM HAuCl₄, and 2.6 mL of 0.1 M ascorbic acid were added at 25 °C. Next, 12 mL of the previously prepared seed solution was added under stirring and the mixture was allowed to age for at least 4 h until it turned dark brown. After that time, the longitudinal LSPR band should be centered around 730 nm. The obtained particles were centrifuged at 23140 rcf for 45 min in 2 mL tubes and redispersed in 5.5 mL of 10 mM CTAB, yielding a final Au⁰ concentration of 10 mM.

3) *Synthesis of “minirods”.* On a 500mL Erlenmeyer flask, 200 mL solution of CTAB 50mM and n-decanol 13.5 mM was prepared. Then, 1.6mL of AgNO₃ (10mM), 14mL of HCl (1M) (HCl volume must be adjusted as specified on [1]), 2mL of HAuCl₄ (50mM) and 2.6 mL of ascorbic acid (0.1M) were subsequently added at 25°C. Then, 12mL of previously prepared seed solution was added under stirring and the mixture is left aging for at least 4 hours until it turns dark brown. After that time, longitudinal plasmon should peak at 730nm and the final particles are
centrifuged at 15000 rpm for 45 minutes in 2mL tubes and dispersed in 5,5mL of
CTAB 10mM for a final Au�0 concentration of 10mM.

4) **Synthesis of achiral AuNRs:** First, 174 mL of an aqueous solution containing 50 mM CTAB and 11 mM n-decanol was prepared. Then, 2 mL of 50 mM HAuCl₄ was added, and the resulting yellowish solution was left undisturbed for 10 min at 16 °C. Afterwards, 3 mL of 10 mM AgNO₃, 20 mL of 1 M HCl, 1.6 mL of 0.1 M ascorbic acid, and 400 µL of 10 mM Au “minirods” were sequentially added. The resulting mixture was left undisturbed for 5 hours to allow complete anisotropic growth. Then, the particles were centrifuged at 5750 rcf for 20 min in 50 mL tubes and redispersed in 5 mL of 1 mM CTAB, yielding a final Au⁰ concentration of 5 mM. The LSPR maximum was at 1150 nm.

5) **Chiral gold nanoparticles.** Typically, 200 µL of HAuCl4 (10 mM) was dispersed on 10 mL of 10 mM CTAC solution and incubated at 40°C for 8-10 min. Then, for the chiral nanoparticles with larger aspect ratio, 200 µL of L-ascorbic acid (0.1 M), 40 to 60 µL of L-/D-cysteine (20 µM) and 12 µL of achiral gold nanorods with LSPR at 1150 nm (5 mM) were added sequentially. For chiral particles with smaller aspect ratio, 200 µL of L-ascorbic acid (0.1 M), 120 µL of L-/D-cysteine (20 µM) and 14 µL of achiral gold nanorods with LSPR at 1040 nm (5 mM) were added instead. The particles were then centrifuged (10 min at 3980 rcf) and dispersed in 1 mM CTAC twice.

*Oxidation of cGNRs.* cGNRs with different degrees of oxidation were prepared by a procedure described in Jessica Rodríguez-Fernández et. al.⁵² with slight modifications. 2.5 mL of 2 mM cGNRs dispersed in CTAC 1 mM were added into 20 mL solution of CTAB (50 mM). Subsequently, 100 µL of HAuCl₄ (50 mM) was added under stirring (500 rpm). The oxidation was then stopped by centrifugation (10 min at 4700 rcf twice dispersing the particles in 1 mM CTAC) at different times to yield cGNR_2 and cGNR_3 after 3h and 24h respectively.

*Self-Assembly by EISA.* A 10 µL drop of cGNRs (30 mM Au⁰, 2.5 mM CTAC) is drop casted onto a substrate (either a silicon wafer or a glass coverslip), and allowed for around 48 h. While Si wafers were preferred for SEM characterization, glass coverslips were preferred for SAXS characterization. Throughout the drying process, the sample is placed in a covered container with added water droplets to maintain saturated humidity, thereby slowing down evaporation.
*Self-assembly by DISA.* Two procedures were tested for DISA resulting in slow or fast self-assembly kinetics, as described in the following. This was tested as slow kinetics are known to induce more extended assemblies, including in DISA.⁵³ While results displayed in Figure S13 shows an effect of the self-assembly kinetics, the shape of the cGNRs induced more notable effects on the size of the assemblies.

1) Slow kinetics. This procedure is adapted from.⁵³ Into a round glass capillary (diameter = 1.5 mm), 10 µL of cGNR suspension (35 mM Au⁰ in cGNRs, 1 mM CTAC) is injected with a syringe near the bottom of the capillary, leaving an air pocket below of several millimeters from the bottom. Then, 20 µL of aqueous cetyltrimethylammonium chloride (CTAC) solution (at varying CTAC concentration) was carefully deposited on top with a syringe, ensuring a sharp and well-defined interface between the two phases. Finally, the capillaries were sealed using a glue gun and left undisturbed for at least 24 hours to allow diffusion and equilibration before characterization by SAXS.

2) Fast kinetics. Into a polystyrene cuvette (optical path length = 1 cm), 10 µL of cGNRs suspension (35 mM Au⁰ in cGNRs, 1 mM CTAC) was rapidly mixed with 1990 µL of aqueous CTAC (at a chosen surfactant concentration).

*Reconfigurable PCD.* On a 10 mL centrifuge tube 2 mL of CTAC 87.5 mM and 500 µL of cGNRs were added for a final concentration of 70 mM CTAC. The CD and extinction spectra were immediately measured one after another in order to calculate the *g*-factor at the optimal assemble stage. Then, the sample was either let undisturbed until total sedimentation of the nanoparticles or centrifuged at 2240 rcf for 5 minutes to accelerate the sedimentation process, yielding the same result. The supernatant was then carefully removed and the remaining NPs were dispersed in 2.5 mL of 1 mM CTAC. The CD and extinction spectra were then measured again, followed by another centrifugation at 3980 rcf for 10 minutes. The supernatant was discarded and precipitates at the bottom of the tube were dispersed with CTAC 70 mM completing one cycle as shown in Figure 4G.

*Small Angle X-Ray Scattering.* SAXS data was collected at the SWING beamline of the SOLEIL Synchrotron (Saint-Aubin, France), using a beam energy of 12 keV and a sample-to-detector distance of 6.22 m. Each measurements had an exposure time of 1000 ms. The beam size was approximately 500 × 200 µm² (horizontal × vertical). For colloidal samples in capillaries, a z-scan of the capillary was performed, while for dried samples prepared via EISA on a glass substrate, a radial scan of the droplet was conducted, measuring multiple points from
the edge to the center. All measurements were performed at room temperature (295 K). The scattered signal was recorded using an Eiger 4 M detector (Dectris Ltd., Switzerland) with a pixel size of 75 µm. Preliminary data treatment, including angular averaging and normalization, was performed using Foxtrot, the dedicated software developed at the beamline (https://www.synchrotron-soleil.fr/fr/lignes-de-lumiere/swing). The processed data yielded intensity as a function of the scattering vector I(q), in absolute units. Further SAXS data modeling and analysis were conducted using either custom Python scripts or SasView 6.0.0.

*Transmission electron microscopy, electron tomography and helicity measurements.* Scanning transmission electron microscopy (STEM) and electron tomography experiments (ET) were performed using a “cubed” Thermo Fisher Scientific Themis Z instrument operated at 300 kV in high angle annular dark field STEM (HAADF-STEM) mode. Electron tomography (ET) series were acquired over an angular range of ±75°, with a tilt increment of 3°, and were used as an input for SIRT reconstruction using the Astra Toolbox 1.8 for MATLAB R2019A.⁵⁴ Visualization of the 3D reconstructions was performed using the Amira 5.4.0 software. The helical morphology of cGNRs was quantitatively characterized using an updated version of our previously reported method.³⁷ Liquid and cryo studies of assemblies of chiral NPs was performed using a single-use sealable sample holder (K-KIT) and 2550 Cryo Transfer Tomography Holder (Fischione Instruments) respectively.

## Acknowledgment

The CNRS is acknowledged for funding and support. C.H. acknowledges financial support from the ANR CODENAME project (ANR-23-CE09-0032). The authors acknowledge SOLEIL for the provision of synchrotron radiation facilities (experiments 20231786) and we would like to thank Thomas Bizien for assistance in using beamline SWING. The authors thanks Stéphan Rouzière for the use of the MORPHEUS platform. The present work had benefited from the electronic microscopy facility of Imagerie-Gif, (http://www.i2bc.parissaclay.fr), member of IBiSA (http://www.ibisa.net), supported by “France-BioImaging” (ANR10-INBS-04-01), and the Labex “Saclay Plant Science” (ANR-11-IDEX-0003-02). M.M. and S.B. acknowledge financial support by the European Research Council (ERC CoG No. 815128 REALNANO). I.P.-S., J.P.-J. acknowledge the support from MICIU/AEI/10.13039/501100011033 and ERDF/EU (Grant Number: PID2022-138724NB-I00) and the Xunta de Galicia/ERDF (grant GRC ED431C 2020/09). I.P.-S., J.P.-J., L.M.L.-M. and A.S.-F. acknowledge the use of scientific and technical services of Centro de Apoio Científico e Tecnolóxico á Investigación (CACTI-Universidade de Vigo). L.M.L.-M. and S.B.
acknowledge funding from the European Research Council (ERC Synergy Grant #101166855 CHIRAL-PRO).

**Supporting Information Available**

The supporting information contains: TEM image analysis of the cGNRs, SEM image analysis of the supercrystals, SAXS analysis of the supercrystals obtained by DISA and EISA, additional SEM images of the self-assembled systems, electron tomography reconstructions images of the assemblies, additional optical characterization of the assemblies by CD and extinction spectroscopy.

**References**

(1) Cho, N. H.; Guerrero-Martínez, A.; Ma, J.; Bals, S.; Kotov, N. A.; Liz-Marzán, L. M.; Nam, K. T. Bioinspired chiral inorganic nanomaterials. *Nat. Rev. Bioengineer.* **2023**, *1* (2), 88-106.

(2) Ávalos-Ovando, O.; Santiago, E. Y.; Movsesyan, A.; Kong, X.-T.; Yu, P.; Besteiro, L. V.; Khorashad, L. K.; Okamoto, H.; Slocik, J. M.; Correa-Duarte, M. A.; et al. Chiral Bioinspired Plasmonics: A Paradigm Shift for Optical Activity and Photochemistry. *ACS Photonics* **2022**, *9* (7), 2219-2236.

(3) Hentschel, M.; Schäferling, M.; Duan, X.; Giessen, H.; Liu, N. Chiral plasmonics. *Sci. Adv.* **2017**, *3* (5), e1602735.

(4) Goerlitzer, E. S. A.; Puri, A. S.; Moses, J. J.; Poulikakos, L. V.; Vogel, N. The Beginner's Guide to Chiral Plasmonics: Mostly Harmless Theory and the Design of Large-Area Substrates. *Adv. Opt. Mater.* **2021**, *9* (16), 2100378.

(5) Kim, R. M.; Huh, J. H.; Yoo, S.; Kim, T. G.; Kim, C.; Kim, H.; Han, J. H.; Cho, N. H.; Lim, Y. C.; Im, S. W.; et al. Enantioselective sensing by collective circular dichroism. *Nature* **2022**, *612* (7940), 470-476.

(6) Negrin-Montecelo, Y.; Movsesyan, A.; Gao, J.; Burger, S.; Wang, Z. M.; Nlate, S.; Pouget, E.; Oda, R.; Comesana-Hermo, M.; Govorov, A. O.; et al. Chiral Generation of Hot Carriers for Polarization-Sensitive Plasmonic Photocatalysis. *J. Am. Chem. Soc.* **2022**, *144* (4), 1663-1671.

(7) Both, S.; Schaferling, M.; Sterl, F.; Muljarov, E. A.; Giessen, H.; Weiss, T. Nanophotonic Chiral Sensing: How Does It Actually Work? *ACS Nano* **2022**, *16* (2), 2822-2832.

(8) Warning, L. A.; Miandashti, A. R.; McCarthy, L. A.; Zhang, Q.; Landes, C. F.; Link, S. Nanophotonic Approaches for Chirality Sensing. *ACS Nano* **2021**, *15* (10), 15538-15566.
(9) Im, S. W.; Ahn, H. Y.; Kim, R. M.; Cho, N. H.; Kim, H.; Lim, Y. C.; Lee, H. E.; Nam, K. T. Chiral Surface and Geometry of Metal Nanocrystals. *Adv. Mater.* **2020**, *32* (41), e1905758.

(10) Kumar, J.; Eraña, H.; López-Martínez, E.; Claes, N.; Martín, V. F.; Solís, D. M.; Bals, S.; Cortajarena, A. L.; Castilla, J.; Liz-Marzán, L. M. Detection of amyloid fibrils in Parkinson's disease using plasmonic chirality. *Proc. Natl. Acad. Sci. U. S. A.* **2018**, *115* (13), 3225-3230.

(11) Tadgell, B.; García-Astrain, C.; Henriksen-Lacey, M.; Martín, V. F.; Obelleiro-Liz, M.; Liz-Marzán, L. M. Monitoring of the Local Extracellular Environment Using Chiral Gold Nanoparticles. *J. Am. Chem. Soc.* **2025**, *147* (3), 2860-2870.

(12) Lee, H.-E.; Ahn, H.-Y.; Mun, J.; Lee, Y. Y.; Kim, M.; Cho, N. H.; Chang, K.; Kim, W. S.; Rho, J.; Nam, K. T. Amino-acid- and peptide-directed synthesis of chiral plasmonic gold nanoparticles. *Nature* **2018**, *556* (7701), 360-365.

(13) González-Rubio, G.; Mosquera, J.; Kumar, V.; Pedrazo-Tardajos, A.; Llombart, P.; Solís, D. M.; Lobato, I.; Noya, E. G.; Guerrero-Martínez, A.; Taboada, J. M.; et al. Micelle-directed chiral seeded growth on anisotropic gold nanocrystals. *Science* **2020**, *368* (6498), 1472-1477.

(14) Chen, W.; Bian, A.; Agarwal, A.; Liu, L.; Shen, H.; Wang, L.; Xu, C.; Kotov, N. A. Nanoparticle Superstructures Made by Polymerase Chain Reaction: Collective Interactions of Nanoparticles and a New Principle for Chiral Materials. *Nano Lett.* **2009**, *9* (5), 2153-2159.

(15) George, J.; Thomas, K. G. Surface Plasmon Coupled Circular Dichroism of Au Nanoparticles on Peptide Nanotubes. *J. Am. Chem. Soc.* **2010**, *132* (8), 2502-2503.

(16) Guerrero-Martínez, A.; Auguié, B.; Alonso-Gómez, J. L.; Džolić, Z.; Gómez-Graña, S.; Žinić, M.; Cid, M. M.; Liz-Marzán, L. M. Intense Optical Activity from Three-Dimensional Chiral Ordering of Plasmonic Nanoantennas. *Angew. Chem. Int. Ed.* **2011**, *50* (24), 5499-5503.

(17) Lu, J.; Xue, Y.; Bernardino, K.; Zhang, N.-N.; Gomes, W. R.; Ramesar, N. S.; Liu, S.; Hu, Z.; Sun, T.; de Moura, A. F.; et al. Enhanced optical asymmetry in supramolecular chiroplasmonic assemblies with long-range order. *Science* **2021**, *371* (6536), 1368-1374.

(18) Zhang, N. N.; Mychinko, M.; Gao, S. Y.; Yu, L.; Shen, Z. L.; Wang, L.; Peng, F.; Wei, Z.; Wang, Z.; Zhang, W.; et al. Self-Matching Assembly of Chiral Gold Nanoparticles Leads to High Optical Asymmetry and Sensitive Detection of Adenosine Triphosphate. *Nano Lett.* **2024**, *24* (41), 13027-13036.

(19) Wang, S.; Zheng, L. H.; Chen, W. J.; Ji, L. K.; Zhang, L.; Lu, W. S.; Fang, Z. Y.; Guo, F. C.; Qi, L. M.; Liu, M. H. Helically Grooved Gold Nanoarrows: Controlled Fabrication, Superhelix, and Transcribed Chiroptical Switching. *Ccs Chemistry* **2021**, *3* (9), 2473-2484.
(20) Carone, A.; Mariani, P.; Désert, A.; Parola, S. Colloidal Assemblies of Chiral Plasmonic Nanoparticles Induce Tunable Circular Dichroism Response. *Adv. Opt. Mater.* **2023**, *11* (18), 2300119.

(21) Yao, C.; He, H.; Kong, W.; Hu, L.; Shen, X.; Tao, J.; Sang, Y.; Nie, Z. Polymer-Driven Co-Assembly of Achiral and Chiral Nanoparticles into Plasmonic Nanoclusters with Quantitatively Modulated Optical Chirality. *Adv. Sci.*, e04850. DOI: https://doi.org/10.1002/advs.202504850.

(22) Maniappan, S.; Dutta, C.; Solís, D. M.; Taboada, J. M.; Kumar, J. Surfactant Directed Synthesis of Intrinsically Chiral Plasmonic Nanostructures and Precise Tuning of their Optical Activity through Controlled Self-Assembly. *Angew. Chem. Int. Ed.* **2023**, *62* (21), e202300461.

(23) Frenkel, D. Order through entropy. *Nat. Mater.* **2015**, *14* (1), 9-12

(24) Vo, T.; Glotzer, S. C. A theory of entropic bonding. *Proc. Natl. Acad. Sci. U S A* **2022**, *119* (4), e2116414119.

(25) Young, K. L.; Personick, M. L.; Engel, M.; Damasceno, P. F.; Barnaby, S. N.; Bleher, R.; Li, T.; Glotzer, S. C.; Lee, B.; Mirkin, C. A. A directional entropic force approach to assemble anisotropic nanoparticles into superlattices. *Angew. Chem. Int. Ed.* **2013**, *52* (52), 13980-13984.

(26) Lekkerkerker, H. N. W.; Tuinier, R.; Vis, M. Phase Behaviour of Colloidal Platelet-Depletant Mixtures. In *Colloids and the Depletion Interaction*, Lekkerkerker, H. N. W., Tuinier, R., Vis, M. Eds.; Lecture Notes in Physics, Springer International Publishing, 2024; pp 285-317.

(27) Young, K. L.; Jones, M. R.; Zhang, J.; Macfarlane, R. J.; Esquivel-Sirvent, R.; Nap, R. J.; Wu, J.; Schatz, G. C.; Lee, B.; Mirkin, C. A. Assembly of reconfigurable one-dimensional colloidal superlattices due to a synergy of fundamental nanoscale forces. *Proc. Natl. Acad. Sci. U S A* **2012**, *109* (7), 2240-2245.

(28) Chiu, C.-Y.; Chen, C.-K.; Chang, C.-W.; Jeng, U. S.; Tan, C.-S.; Yang, C.-W.; Chen, L.-J.; Yen, T.-J.; Huang, M. H. Surfactant-Directed Fabrication of Supercrystals from the Assembly of Polyhedral Au-Pd Core-Shell Nanocrystals and Their Electrical and Optical Properties. *J. Am. Chem. Soc.* **2015**, *137* (6), 2265-2275.

(29) Nag, R.; Rouviere, N.; Trazo, J. G.; Marcone, J.; Kutalia, N.; Goldmann, C.; Imperor-Clerc, M.; Alloyeau, D.; Constantin, D.; Hamon, C. Depletion-Induced Tunable Assembly of Complementary Platonic Solids. *Nano Lett.* **2024**, *24* (51), 16368-16373.

(30) Urban, M. J.; Shen, C.; Kong, X.-T.; Zhu, C.; Govorov, A. O.; Wang, Q.; Hentschel, M.; Liu, N. Chiral Plasmonic Nanostructures Enabled by Bottom-Up Approaches. *Annu. Rev. Phys. Chem.* **2019**, *70* (Volume 70, 2019), 275-299.
(31) Neubrech, F.; Hentschel, M.; Liu, N. Reconfigurable Plasmonic Chirality: Fundamentals and Applications. *Adv. Mater.* **2020**, *32* (41), e1905640.

(32) Kuzyk, A.; Schreiber, R.; Zhang, H.; Govorov, A. O.; Liedl, T.; Liu, N. Reconfigurable 3D plasmonic metamolecules. *Nat. Mater.* **2014**, *13* (9), 862-866

(33) Bagiński, M.; Tupikowska, M.; González-Rubio, G.; Wójcik, M.; Lewandowski, W. Shaping Liquid Crystals with Gold Nanoparticles: Helical Assemblies with Tunable and Hierarchical Structures Via Thin-Film Cooperative Interactions. *Adv. Mater.* **2020**, *32* (1), 1904581.

(34) Jedrych, A.; Pawlak, M.; Gorecka, E.; Lewandowski, W.; Wojcik, M. M. Light-Responsive Supramolecular Nanotubes-Based Chiral Plasmonic Assemblies. *ACS Nano* **2023**, *17* (6), 5548-5560.

(35) Liu, N.; Liedl, T. DNA-Assembled Advanced Plasmonic Architectures. *Chem. Rev.* **2018**, *118* (6), 3032-3053.

(36) Ni, B.; Mychinko, M.; Gomez-Grana, S.; Morales-Vidal, J.; Obelleiro-Liz, M.; Heyvaert, W.; Vila-Liarte, D.; Zhuo, X.; Albrecht, W.; Zheng, G.; et al. Chiral Seeded Growth of Gold Nanorods Into Fourfold Twisted Nanoparticles with Plasmonic Optical Activity. *Adv. Mater.* **2023**, *35* (1), e2208299.

(37) Heyvaert, W.; Pedrazo-Tardajos, A.; Kadu, A.; Claes, N.; González-Rubio, G.; Liz-Marzán, L. M.; Albrecht, W.; Bals, S. Quantification of the Helical Morphology of Chiral Gold Nanorods. *ACS Mater. Lett.* **2022**, *4* (4), 642-649.

(38) Han, W.; Lin, Z. Learning from “Coffee Rings”: Ordered Structures Enabled by Controlled Evaporative Self-Assembly. *Angew. Chem. Int. Ed.* **2012**, *51* (7), 1534-1546.

(39) Marín, Á. G.; Gelderblom, H.; Lohse, D.; Snoeijer, J. H. Order-to-Disorder Transition in Ring-Shaped Colloidal Stains. *Phys. Rev. Lett.* **2011**, *107* (8), 085502.

(40) Deegan, R. D.; Bakajin, O.; Dupont, T. F.; Huber, G.; Nagel, S. R.; Witten, T. A. Capillary flow as the cause of ring stains from dried liquid drops. *Nature* **1997**, *389* (6653), 827-829.

(41) Xie, Y.; Guo, S.; Ji, Y.; Guo, C.; Liu, X.; Chen, Z.; Wu, X.; Liu, Q. Self-Assembly of Gold Nanorods into Symmetric Superlattices Directed by OH-Terminated Hexa(ethylene glycol) Alkanethiol. *Langmuir* **2011**, *27* (18), 11394-11400.

(42) Marcone, J.; Chaabani, W.; Goldmann, C.; Emperor-Clerc, M.; Constantin, D.; Hamon, C. Polymorphous Packing of Pentagonal Nanoprisms. *Nano Lett.* **2023**, *23* (4), 1337-1342.

(43) Gómez-Graña, S.; Pérez-Juste, J.; Alvarez-Puebla, R. A.; Guerrero-Martínez, A.; Liz-Marzán, L. M. Self-Assembly of Au@Ag Nanorods Mediated by Gemini Surfactants for Highly Efficient SERS-Active Supercrystals. *Adv. Opt. Mater.* **2013**, *1* (7), 477-481.
(44) Li, T.; Senesi, A. J.; Lee, B. Small Angle X-ray Scattering for Nanoparticle Research. *Chem. Rev.* **2016**, *116* (18), 11128-11180.

(45) Gomez-Grana, S.; Hubert, F.; Testard, F.; Guerrero-Martinez, A.; Grillo, I.; Liz-Marzan, L. M.; Spalla, O. Surfactant (bi)layers on gold nanorods. *Langmuir* **2012**, *28* (2), 1453-1459.

(46) Goldmann, C.; Chaabani, W.; Hotton, C.; Emperor-Clerc, M.; Moncomble, A.; Constantin, D.; Alloyeau, D.; Hamon, C. Confinement Effects on the Structure of Entropy-Induced Supercrystals. *Small* **2023**, *19* (44), e2303380.

(47) Halas, N. J.; Lal, S.; Chang, W.-S.; Link, S.; Nordlander, P. Plasmons in Strongly Coupled Metallic Nanostructures. *Chem. Rev.* **2011**, *111* (6), 3913-3961.

(48) Gu, T.; Kim, H. J.; Rivero-Baleine, C.; Hu, J. J. Reconfigurable metasurfaces towards commercial success. *Nat. Photonics* **2023**, *17* (1), 48-58.

(49) Neubrech, F.; Duan, X.; Liu, N. Dynamic plasmonic color generation enabled by functional materials. *Sci. Adv.* **2020**, *6* (36), eabc2709

(50) Scarabelli, L.; Sánchez-Iglesias, A.; Pérez-Juste, J.; Liz-Marzán, L. M. A “Tips and Tricks” Practical Guide to the Synthesis of Gold Nanorods. *J. Phys. Chem. Lett.* **2015**, *6* (21), 4270-4279.

(51) González-Rubio, G.; Kumar, V.; Llombart, P.; Díaz-Núñez, P.; Bladt, E.; Altantzis, T.; Bals, S.; Peña-Rodríguez, O.; Noya, E. G.; MacDowell, L. G.; et al. Disconnecting Symmetry Breaking from Seeded Growth for the Reproducible Synthesis of High Quality Gold Nanorods. *ACS Nano* **2019**, *13* (4), 4424-4435.

(52) Rodríguez-Fernández, J.; Pérez-Juste, J.; Mulvaney, P.; Liz-Marzán, L. M. Spatially-Directed Oxidation of Gold Nanoparticles by Au(III)-CTAB Complexes. *J. Phys. Chem. B* **2005**, *109* (30), 14257-14261.

(53) Yang, P. W.; Thoka, S.; Lin, P. C.; Su, C. J.; Sheu, H. S.; Huang, M. H.; Jeng, U. S. Tracing the Surfactant-Mediated Nucleation, Growth, and Superpacking of Gold Supercrystals Using Time and Spatially Resolved X-ray Scattering. *Langmuir* **2017**, *33* (13), 3253-3261.

(54) van Aarle, W.; Palenstijn, W. J.; De Beenhouwer, J.; Altantzis, T.; Bals, S.; Batenburg, K. J.; Sijbers, J. The ASTRA Toolbox: A platform for advanced algorithm development in electron tomography. *Ultramicroscopy* **2015**, *157*, 35-47.

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