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Determining the structural chirality of biomolecules is of vital importance in bioscience and biomedicine. Conventional methods for characterizing molecular chirality, e.g., circular dichroism (CD) spectroscopy, require high-concentration specimens due to the weak electronic CD signals of biomolecules such as amino acids. Artificially designed chiral plasmonic metastructures exhibit strong intrinsic chirality. However, the significant size mismatch between metastructures and biomolecules makes the former unsuitable for chirality-recognition-based molecular discrimination. Fortunately, constructing metallic architectures through molecular self-assembly allows chirality transfer from sub-nanometer biomolecules to sub-micrometer, intrinsically achiral plasmonic metastructures by means of either near-field interaction or chirality inheritance, resulting in hybrid systems with CD signals orders of magnitude larger than that of pristine biomolecules. This exotic property provides a new means to determine molecular chirality at extremely low concentrations (ideally at the single-molecule level). Herein, three strategies of chirality transfer from sub-nanometer biomolecules to sub-micrometer metallic metastructures are analyzed. The physiochemical mechanisms responsible for chirality transfer are elaborated and new fascinating opportunities for employing plasmonic metastructures in chirality-based biosensing and bioimaging are outlined.

Nine guaiane-type sesquiterpenes and one eudesmane-type one – namely argyinolides A–J (1–10) – as well as nine known analogues were isolated from the leaves of Artemisia argyi Levl. et Vant. Their structures were determined by interpretation of spectroscopic data (MS, 1D and 2D NMR). A combination of X-ray crystal diffraction, specific optical rotations, CD spectroscopy, ECD calculation, and Mosher ester methods was employed to resolve the absolute configurations of the isolated compounds. Biological investigations into their cytotoxicities and anti-inflammatory effects showed that 1, 13, 16, and 18 were remarkably cytotoxic against Bel-742 and/or A549 cells, with IC50 values of 3.3–6.0 μM, whereas 7, 11–13, 16, and 18 exhibited sound inhibitory activity on LPS-stimulated NO production in BV-2 microglial cells, with IC50 values ranging from 3.2 to 8.6 μM. In addition, a brief discussion on the applicability of Geissman's rule for the sesquiterpene lactones, the probable reason for the presence of chlorine-containing sesquiterpenes, and preliminary structure–activity relationships (SARs) are included.

The DNA cleavage activities of nickel(II) ion and four closely related macrocyclic nickel(II) complexes NiL 1 ∼ NiL 4 in the absence of any added redox cofactors are compared and the structure of NiL 3 methanol solvate has been characterized by single crystal X-ray analysis, where L 1 ∼ L 4 are the dianions of tetraazamacrocyclic oxamido Schiff bases. In NiL 3 ·MeOH, the macrocyclic [N 4 ] ligand coordinates to the central Ni(II) ion forming a distorted square–planar geometry. The adjacent mononuclear molecules are linked by O–H⋯O hydrogen bonds and Ni⋯O and Ni⋯L van der Waals forces into 2D supramolecular structure. Agarose gel electrophoresis studies indicate that the ability of these nickel(II) complexes to cleave DNA is highly dependent upon the ligand employed. In the absence of any added oxidizing agents, only NiL 3 is a relatively good DNA cleavage agent, and the process of plasmid DNA cleavage is much sensitive to ionic strength and pH value. The NiL 3 -mediated DNA cleavage reaction is a typical pseudo-first-order consecutive reaction, and the rate constants of 0.148 ± 0.007 h −1 ( k 1 ) and 0.0118 ± 0.0018 h −1 ( k 2 ) for the conversion of supercoiled to nicked DNA and nicked to linear DNA are obtained in presence of 0.5 mmol L −1 NiL 3 . The results of DNA cleavage experiments, combining with those of circular dichroism (CD) and fluorescence spectroscopy indicate that the main binding modes between DNA and the complexes should be groove binding and electrostatic interaction.

We demonstrate a lattice of 3D chiral plasmonic nano-holes, with strong relative optical circular dichroism ~0.5 and high Q-factor up to 45. The area of the lattice can be fabricated to 1cm2 with nearly perfect consistency of every unit cell. We show that this CD enhancement is due to the interaction between the chiral response of the chiral holes and the scattering modes of the lattice.