3D hierarchic interfacial assembly of Au nanocage@Au along with IS-AgMNPs for simultaneous, ultrasensitive, reliable, and quantitative SERS detection of colorectal cancer related miRNAs.

Simultaneous, reliable, and ultra-sensitive analysis of promising miRNA biomarkers of colorectal cancer (CRC) in serum is critical for early diagnosis and prognosis of CRC. In this work, we proposed a novel 3D hierarchic assembly clusters-based SERS strategy with dual enrichment and enhancement designed for the ultrasensitive and quantitative analysis of two upregulated CRC-related miRNAs (miR-21 and miR-31). The biosensor contains the following: (1) SERS probe, Au nanocage@Au nanoparticles (AuNC@Au NPs) labeled with Raman reporters (RaRs). (2) magnetic capture unit, Ag-coated Fe3O4 magnetic nanoparticles (AgMNPs) modified with internal standard (IS). (3) signal amplify probes (SA probes) for the formation of hierarchic assembly clusters. Based on this sensing strategy, the intensity ratio IRaRs/IIS with Lg miRNAs presents a wide linear range (10 aM-100 pM) with a limit of detection of 3.46 aM for miR-21, 6.49 aM for miR-31, respectively. Moreover, the biosensor shows good specificity and anti-interference ability, and the reliability and repeatability of the strategy were then verified by practical detection of clinical serum. Finally, the biosensor can distinguish CRC cancer subjects from normal ones and guide the distinct tumor, lymph node, and metastasis (TNM) stages. Overall, benefiting from the face-to-face coupling of hierarchic assembly clusters, rapid magnetic enrichment and IS signal calibration of AgMNPs, the established biosensor achieves ultra-sensitive and simultaneous detection of dual miRNAs and opens potential avenues for prediction and staging of CRC.

Histidine-Mediated Synthesis of Chiral Cobalt Oxide Nanoparticles for Enantiomeric Discrimination and Quantification.

Chiral transition metal oxide nanoparticles (CTMOs) are attracting a lot of attention due to their fascinating properties. Nevertheless, elucidating the chirality induction mechanism often remains a major challenge. Herein, the synthesis of chiral cobalt oxide nanoparticles mediated by histidine (Co3 O4 @L-His and Co3 O4 @D-His for nanoparticles synthesized in the presence of L- and D-histidine, respectively) is investigated. Interestingly, these CTMOs exhibit remarkable and tunable chiroptical properties. Their analysis by x-ray photoelectron, Fourier transform infrared, and ultraviolet-visible absorption spectroscopy indicates that the ratio of Co2+ /Co3+ and their interactions with the imidazole groups of histidine are behind their chiral properties. In addition, the use of chiral Co3 O4 nanoparticles for the development of sensitive, rapid, and enantioselective circular dichroism-based sensors is demonstrated, allowing direct molecular detection and discrimination between cysteine or penicillamine enantiomers. The circular dichroism response of the chiral Co3 O4 exhibits a limit of detection and discrimination of cysteine and penicillamine enantiomers as low as 10 µm. Theoretical calculations suggest that the ligand exchange and the coexistence of both species adsorbed on the oxide surface are responsible for the enantiomeric discrimination. This research will enrich the synthetic approaches to obtain CTMOs and enable the extension of the applications and the discovery of new chiroptical properties.

Chiral Seeded Growth of Gold Nanorods Into Fourfold Twisted Nanoparticles with Plasmonic Optical Activity.

A robust and reproducible methodology to prepare stable inorganic nanoparticles with chiral morphology may hold the key to the practical utilization of these materials. An optimized chiral growth method to prepare fourfold twisted gold nanorods is described herein, where the amino acid cysteine is used as a dissymmetry inducer. Four tilted ridges are found to develop on the surface of single-crystal nanorods upon repeated reduction of HAuCl4 , in the presence of cysteine as the chiral inducer and ascorbic acid as a reducing agent. From detailed electron microscopy analysis of the crystallographic structures, it is proposed that the dissymmetry results from the development of chiral facets in the form of protrusions (tilted ridges) on the initial nanorods, eventually leading to a twisted shape. The role of cysteine is attributed to assisting enantioselective facet evolution, which is supported by density functional theory simulations of the surface energies, modified upon adsorption of the chiral molecule. The development of R-type and S-type chiral structures (small facets, terraces, or kinks) would thus be non-equal, removing the mirror symmetry of the Au NR and in turn resulting in a markedly chiral morphology with high plasmonic optical activity.

Tuning the Morphology and Chiroptical Properties of Discrete Gold Nanorods with Amino Acids.

The synthesis of discrete nanostructures with a strong, persistent, stable plasmonic circular dichroism (PCD) signal is challenging. We report a seed-mediated growth approach to obtain discrete Au nanorods with high and stable chiroptical responses (c-Au NRs) in the visible to near-IR region. The morphology of the c-Au NRs was governed by the concentration of l- or d-cysteine used. The amino acids encapsulated within the discrete gold nanostructure enhance their PCD signal, attributed to coupling of dipoles of chiral molecules with the near-field induced optical activity at the hot spots inside the c-Au NRs. The stability of the PCD signal and biocompatibility of c-Au NRs was improved by coating with silica or protein corona. Discrete c-Au NR@SiO2 with Janus or core-shell configurations retained their PCD signal even in organic solvents. A side-by-side assembly of c-Au NRs induced by l-glutathione led to further PCD signal enhancement, with anisotropic g factors as high as 0.048.

The implementation of an integrated computer-aided system for dental implantology.

This paper presents an implementation of different functionalities on a computer-aided system for dental implantology. The integrated system consists of two subsystems corresponding to two main stages of dental implantology respectively. In the preoperative planning subsystem, we provide different kinds of views based on CT data scanned from a specific patient for the dentist. And the dentist can plan implant path according to these views. The intra-operative navigational subsystem uses an infra-red light based navigation camera to locate the precise position of the surgical instrument. At last, an improved experiment on a phantom model studied the error and accuracy, to demonstrate its feasibility on further clinical trial.