Surface Topographical Engineering of Chiral Au Nanocrystals with Chiral Hot Spots for Plasmon-Enhanced Chiral Discrimination

GSH Oligomer-Directed Chiral Au-Helicoid Nanoparticles for Discriminating Penicillamine Enantiomers

Preparing chiral plasmonic nanoparticles (NPs) with strong chiroptical responses is crucial in numerous fields including constructing optical materials, chiral sensing, and chiral-dependent biological processes. However, precise regulation over the chiral optical activity and chiral configuration of plasmonic NPs is still a challenge. In this work, we report Au helicoid NPs with different chiral structures and reversal chirality directed by the oligomeric structure of inducer glutathione (GSH). By precisely controlling the oligomeric structure of GSH and other synthetic parameters, we successfully prepared chiral Au helicoid NPs with a high anisotropy factor of 0.03. The obtained chiral Au NPs demonstrated an excellent performance in discriminating penicillamine (Pen) enantiomers. Our findings provide a construction strategy for chiral Au NPs and contribute insight into the regulation effect of chiral inducers on the growth of chiral metal NPs.

Swiss roll nanoarrays for chiral plasmonic photocatalysis

Manipulating the chirality at nanoscale has drawn great attention among scientists, considering its pivotal role in various applications of current interest, including nano-optics, biomedicine, and photocatalysis. In this work, we delve into this arena by fabricating chiral Swiss roll nanoarray (SRNA) continuous films employing colloidal lithography. The technique permits the dimension of Swiss roll metamaterials to reduce to nanoscale, thus achieving chiroptical response (circular dichroism (CD)) in the visible region. The interplay between the CD signals and plasmon resonance modes is revealed through theoretical simulations, enabling a deep understanding of chiral plasmonic metamaterials. The polarization-sensitive photocatalytic activity of chiral SRNAs is investigated, noting a marked increase in the reaction rate when the chirality of SRNAs matches with the handedness of circularly polarized light (CPL). Notably, the SRNA continuous films based on substrate possess integration and reusability without complex recycling process, enhancing their practicality in applications like sensing and plasmonic nanochemistry, particularly toward polarization-dependent photocatalysis.

Chiral Au-Pd Alloy Nanorods with Tunable Optical Chirality and Catalytically Active Surfaces

Integrating the plasmonic chirality with excellent catalytic activities in plasmonic hybrid nanostructures provides a promising strategy to realize the chiral nanocatalysis toward many chemical reactions. However, the controllable synthesis of catalytically active chiral plasmonic nanoparticles with tailored geometries and compositions remains a significant challenge. Here it is demonstrated that chiral Au-Pd alloy nanorods with tunable optical chirality and catalytically active surfaces can be achieved by a seed-mediated coreduction growth method. Through manipulating the chiral inducers, Au nanorods selectively transform into two different intrinsically chiral Au-Pd alloy nanorods with distinct geometric chirality and tunable optical chirality. By further adjusting several key synthetic parameters, the optical chirality, composition, and geometry of the chiral Au-Pd nanorods are fine-tailored. More importantly, the chiral Au-Pd alloy nanorods exhibit appealing chiral catalytic activities as well as polarization-dependent plasmon-enhanced nanozyme catalytic activity, which has great potential for chiral nanocatalysis and plasmon-induced chiral photochemistry.

Fe Single-Atom Carbon Dots Nanozyme Collaborated with Nucleic Acid Exonuclease III-Driven DNA Walker Cascade Amplification Strategy for Circulating Tumor DNA Detection

Circulating tumor DNA (ctDNA), as a next-generation tumor marker, enables early screening and monitoring of cancer through noninvasive testing. Exploring the development of new methods for ctDNA detection is an intriguing study. In this work, a unique electrochemical biosensor for the ctDNA detector was constructed in the first utilizing Fe single-atom nanozymes-carbon dots (SA Fe-CDs) as a signaling carrier in collaboration with a DNA walker cascade amplification strategy triggered by nucleic acid exonuclease III (Exo III). The electrochemical active surface area of AuNPs/rGO modified onto a glassy carbon electrode (AuNPs/rGO/GCE) was about 1.43 times that of a bare electrode (bare GCE), with good electrical conductivity alongside a high heterogeneous electron transfer rate (5.81 × 10-3 cm s-1), that is, as well as the ability to load more molecules. Sequentially, the DNA walker cascade amplification strategy driven by Exo III effectively converted the target ctDNA into an amplified biosignal, ensuring the sensitivity and specificity of ctDNA. Ultimately, the electrochemical signal was further amplified by introducing SA Fe-CDs nanozymes, which could serve as catalysts for 3,3',5,5'-tetramethylbenzidine (TMB) oxidation with facile responding (Vmax = 0.854 × 10-6 M s-1) and robust annexation (Km = 0.0069 mM). The integration of the triple signal amplification approach achieved detection limits as low as 1.26 aM (S/N = 3) for a linearity spanning from 5 aM to 50 nM. In this regard, our proposal for a biosensor with exceptional assay properties in complicated serum environments had great potential for early and timely diagnosis of cancer.

Probing local charge transfer processes of Pt-Au heterodimers in plasmon-enhanced electrochemistry by CO stripping techniques

CO-stripping experiments are employed as a highly structure-sensitive and in situ strategy to explore the mechanisms of plasmon-enhanced electrooxidation reactions. By using Pt-Au heterodimers as a model catalyst, the plasmon-induced current and potential changes on Pt and Au sites can be identified and explained.

A Liquid-Liquid Interfacial Strategy for Construction of Electroactive Chiral Covalent-Organic Frameworks with the Aim to Enlarge the Testing Scope of Chiral Electroanalysis

Although electroactive chiral covalent-organic frameworks (CCOFs) are considered an ideal platform for chiral electroanalysis, they are rarely reported due to the difficult selection of suitable precursors. Here, a facile strategy of liquid-liquid interfacial polymerization was carried out to synthesize the target electroactive CCOFs Ph-Py+-(S,S)-DPEA·PF6- and Ph-Py+-(R,R)-DPEA·PF6-. That is, a trivalent Zincke salt (4,4',4″-(benzene-1,3,5-triyl)tris(1-(2,4-dinitrophenyl)pyridin-1-ium)) trichloride (Ph-Py+-NO2) and enantiopure 1,2-diphenylethylenediamine (DPEA) were dissolved in water and chloroform, respectively. The Zincke reaction occurs at the interface, resulting in uniform porosity. As expected, the cyclic voltammetry and differential pulse voltammetry measurements showed that the tripyridinium units of the CCOFs afforded obvious electrochemical responses. When Ph-Py+-(S,S)-DPEA·PF6- was modified onto the surface of a glassy carbon electrode as a chiral sensor, the molecules, which included tryptophan, aspartic acid, serine, tyrosine, glutamic acid, mandelic acid, and malic acid, were enantioselectively recognized in the response of the peak current. Very importantly, the discriminative electrochemical signals were derived from Ph-Py+-(S,S)-DPEA·PF6-. The best peak current ratios between l- and d-enantiomers were in the range of 1.31-2.68. Besides, a good linear relationship between peak currents and enantiomeric excess (ee) values was established, which was successfully harnessed to determine the ee values for unknown samples. In a word, the current work provides new insight and potential of electroactive CCOFs for enantioselective sensing in a broad range.