Efficient optical plasmonic tweezer-controlled single-molecule SERS characterization of pH-dependent amylin species in aqueous milieus.

It is challenging to characterize single or a few biomolecules in physiological milieus without excluding the influences of surrounding environment. Here we utilize optical plasmonic trapping to construct a dynamic nanocavity, which reduces the diffraction-limited detection volume and provides reproducible electromagnetic field enhancements to achieve high-throughput single-molecule surface-enhanced Raman spectroscopy (SERS) characterizations in aqueous environments. Specifically, we study human Islet Amyloid Polypeptide (amylin, hIAPP) under different physiological pH conditions by combining spectroscopic experiments and molecular dynamics (MD) simulations. Based on a statistically significant amount of time-dependent SERS spectra, two types of low-populated transient species of hIAPP containing either turn or ß-sheet structure among its predominant helix-coil monomers are characterized during the early-stage incubation at neutral condition, which play a crucial role in driving irreversible amyloid fibril developments even after a subsequent adjustment of pH to continue the prolonged incubation at acidic condition. Our results might provide profound mechanistic insight into the pH-regulated amyloidogenesis and introduce an alternative approach for investigating complex biological processes at the single-molecule level.

Correction: Highly reusable nanoporous silver sheet for sensitive SERS detection of pesticides.

Correction for 'Highly reusable nanoporous silver sheet for sensitive SERS detection of pesticides' by Huanyu Chi et al., Analyst, 2020, 145, 5158-5165, https://doi.org/10.1039/D0AN00999G.

Tumorigenic risk of Angelica sinensis on ER-positive breast cancer growth through ER-induced stemness in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: The root of Angelica sinensis is widely used in traditional Chinese Medicine for relieving gynecological discomforts among the women population. However, its hormone-like effects have raised great attention on whether it is appropriate to use in breast cancer (BC) patients. Hence, this study aimed to investigate the tumorigenic effect of aqueous root extract of Angelica sinensis (AS) on estrogen receptor (ER)-positive BC growth through ER-induced stemness in-vitro and in-vivo. MATERIALS AND METHODS: The chemical composition of the AS was characterized by HPLC. Cell viability was detected by MTS assay. The in-vivo effect of AS was investigated by xenograft model, immunohistochemistry, histology, Western blot, and self-renewal ability assay. Target verification was used by shRNA construction and transfection. Mammosphere formation assay was performed by flow cytometry. RESULTS: AS significantly promoted the proliferation of MCF-7 cells and inhibited the growth of MDA-MB-231 cells. AS significantly induced tumor growth (2.5 mg/kg) in xenograft models and however tamoxifen treatment significantly suppressed the AS-induced tumor growth. AS induced ERα expression in both in-vivo and in-vitro and promoted cancer stem cell activity in ER-positive BC. CONCLUSION: AS shows the tumorigenic potential on ER-positive BC growth through ERα induced stemness, suggesting that the usage of AS is not recommended for BC in terms of safety measures.

Highly reusable nanoporous silver sheet for sensitive SERS detection of pesticides.

Surface-enhanced Raman spectroscopy (SERS) enables pesticide detection at the point-of-need, but its practical application is limited by expensive and disposable SERS substrates. Here, we report a reusable nanoporous silver (NPAg) sheet for the SERS detection of organochlorine pesticides, aiming to maximize the cost-efficiency of substrate regeneration. The NPAg sheet is prepared by a reduction-induced decomposition method without chemical induced random aggregations. This SERS substrate is sensitive to various analytes regardless of their affinity to a metal surface such as rhodamine B, dichlorodiphenyl-trichloroethane (DDT), and lindane due to its large surface area and the coral rock-like morphology. The SERS signal of lindane, a typical organochlorine pesticide, is identified and quantified with a minimum detectable concentration of 3 × 10-7 M (87 ppb), which is below the maximum residue limits in various foods set by the regulators across the world. More importantly, after a few minutes of ultrasonic cleaning in water, the NPAg sheet can be reused at least 20 times with a reproducible SERS activity. Furthermore, the NPAg sheet remains stable in terms of its sensitivity and reusability after several months of bare strorage. Therefore, the NPAg sheet as a SERS substrate holds great promise for mass production and convenient applications in low-cost pesticide analysis.