Construction of Chiral, Helical Nanoparticle Superstructures: Progress and Prospects

Abstract

Chiral objects are defined as nonsuperimposable conformations that are mirror images of each other, much like a pair of left and right hands. In fact, the word "chiral" derives from the Greek word "χειρ" (kheir), which translates to "hand." Most biomolecules exist in only one particular conformation. For example, amino acids within large protein and peptide molecules are exclusively in the l-form (left-handed). It has long been considered that the phenomenon of homochirality (predominant occurrence of one conformation) could be linked to the origin of life. [1] These phenomena have inspired chemists and biologists to isolate, synthesize, and study the properties of chiral molecules. Research interest in chiral nanostructures has escalated rapidly since the early 2000s due to visionary reports that either predicted or demonstrated the potential applications of these materials. [2,3] In 2004, Pendry predicted that chiral metamaterials could be used to achieve negative refraction (Figure 1). [2] Following this seminal work, others demonstrated that such materials lead to circular dichroism (CD), [4] negative phase velocities, [5] and intense gyrotropy, [6] generating significant excitement within this emerging field. These properties can be harnessed to realize optical materials including "perfect lenses," [7] circular polarizers, [3] chiroptical sensors, [8] and negative refractive index materials. [9,10] In addition to these optical applications, chiral metallic nanostructures have been used for detection of biomolecular disease precursors, [11] chiral catalysis, [12] and chiral separations. [13] Many of the promising applications of chiral metallic nanostructures arise in part from their plasmonic chiroptical activity. At the nanoscale, individual metallic particles exhibit unique properties due to their high surface to volume ratio and geometric confinement of electrons. One particularly important property is the localized surface plasmon resonance (LSPR), [14] which occurs when the oscillation of surface electrons matches the frequency of incident photons. The spectral position and intensity of the LSPR depends not only on the size, shape, composition, and dielectric environment of the metallic nanoparticles (NPs) [15,16] but also on their aggregation state or assembly. [17] When metallic NPs are arranged in a chiral geometry, [18] the coupling of individual plasmons leads to collective plasmon oscillation across the entire structure. [19] Chiral NP assemblies may exhibit enhanced optical chirality in Chiral nanoparticle (NP) superstructures, in which discrete NPs are assembled into chiral architectures, represent an exciting and growing class of nanomaterials. Their enantiospecific properties make them promising candidates for a variety of potential applications. Helical NP superstructures are a rapidly expanding subclass of chiral nanomaterials in which NPs are arranged in three dimensions about a screw axis. Their intrinsic asymmetry gives rise to a variety of interesting properties, including plasmonic chir...

Chirality Transfer from Sub‐Nanometer Biochemical Molecules to Sub‐Micrometer Plasmonic Metastructures: Physiochemical Mechanisms, Biosensing, and Bioimaging Opportunities

“…A primary driving force behind this development is the breakthrough in design and fabrication of artificial metallic nanostructures, ranging from top-down techniques such as focused ion beam milling, [40] electron-beam lithography [41] and direct laser writing, [42] to bottom-up methods like chemical synthesis and self-assembly. [39,43] Together with theories that can elegantly describe the interaction between chiral molecules and plasmonic nanostructures, [44][45][46][47] the study of chirality has entered a fast development path. There have been several reviews focusing on various aspects of this field, including fabrication, [39,43,48,49] theories, [50][51][52] and applications.…”

“…[39,43] Together with theories that can elegantly describe the interaction between chiral molecules and plasmonic nanostructures, [44][45][46][47] the study of chirality has entered a fast development path. There have been several reviews focusing on various aspects of this field, including fabrication, [39,43,48,49] theories, [50][51][52] and applications. [38,53,54] The goal of the present review, as illustrated in Scheme 1, is to elaborate the three physiochemical mechanisms of chirality transfer from sub-nanometer biochemical molecules to submicrometer metallic nanostructures, namely electromagnetic interaction induced chirality transfer, chiral assembly and chirality inheritance, molecular conformation change induced chirality.…”

Dynamic tuning of enhanced intrinsic circular dichroism in plasmonic stereo-metamolecule array with surface lattice resonance

“…Over the past decade, the extraordinary CD responses of plasmonic chiral nanostructures have gained considerable attention, where the excitation of localized surface plasmon resonances (LSPRs) significantly enhances the light-structure interaction strength due to their extremely large dipole moments, and the generated CD signals are thus orders of magnitude larger than that of natural compounds [9][10][11][12][13][14][15][16][17]. Such enhanced plasmonic chirality is also featured with flexible modulation of both CD resonance magnitude and frequency through manipulating the structural geometry and constituents [4,18,19].…”

Chiral Transition Metal Oxides: Synthesis, Chiral Origins, and Perspectives

“…The introduction of chirality to TMOs has revolutionized the motif of TMOs with respect to their applications in area of chiroptical sensing and detection, enantioselective catalysis, biological‐tissue‐based therapy, and chirality‐based devices. Since a body of related reviews has well summarized the details about the possible applications of chiral inorganic NCs, [ 6,47–55 ] we would prefer only to highlight some representative examples of chiral TMOs here: 1)Chiroptical sensing and detection: Xu and co‐workers [ 56 ] reported recently that chiral CuxOS@ZIF‐8 nanostructures can be used as ultrasensitive probe for detection of H 2 S in vivo with the limit of detection of 0.3 × 10 −9 and 2.2 × 10 −9 m for CD and fluorescence methods because H 2 S can reduce the chiroptical intensity and increase the fluorescent signal of the nanostructures ( Figure A). Jiang's group [ 57 ] also demonstrated that cysteine‐capped Au/Fe 3 O 4 NPs can enantioselectively detect the percentage of d ‐tyrosine in a mixture of enantiomers via cysteine as the chiral selector. 2)Enantioselective catalysis: Qu and co‐workers [ 58 ] developed phenylalanine‐modified cerium oxide nanoparticles (CeNPs) as chiral nanozyme for stereoselective oxidation of 3,4‐dihydroxyphenylalanine (DOPA) enantiomers where l ‐CeNP showed higher catalytic ability for oxidation of d ‐DOPA while d ‐CeNP were more effective to l ‐DOPA (Figure 4B).…”