This Communication reports a novel colorimetric sensor to probe histidine in water based on para-sulfonatocalix[4]arene-modified silver nanoparticles; this highly selective sensor allows a rapid quantitative assay of histidine down to a concentration of 5 × 10⁻⁶ M, providing a new tool for the direct measurement of histidine.

Fluorescent theranostics probes at the second near-IR region (NIR-II; 1.0–1.7 µm) are in high demand for precise theranostics that minimize autofluorescence, reduce photon scattering, and improve the penetration depth. Herein, we designed and synthesized an NIR-II theranostic nanoprobe 1 that incorporates a Pt(II) metallacycle 2 and an organic molecular dye 3 into DSPE-mPEG5000 (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-5000]). This design endows 1 with good photostability and passive targeting ability. Our studies show that 1 accurately diagnoses cancer with high resolution and selectively delivers the Pt(II) metallacycle to tumor regions via an enhanced permeability and retention effect. In vivo studies reveal that 1 efficiently inhibits the growth of tumor with minimal side effects. At the same time, improved fluorescent imaging quality and signal-to-noise ratios are shown due to the long emission wavelengths. These studies demonstrate that 1 is a potential theranostic platform for tumor diagnosis and treatment in the NIR-II region. Significance The biomedical applications of fluorescent anticancer agents in the first near-IR region (NIR-I) have been hampered by problems of photostability, autofluorescence, and limited penetration depth in biological tissues. To shift the fluorescence theranostic region from the NIR-I to the longer-wavelength region for accurate cancer diagnosis and treatment, Pt(II) metallacycle-based fluorescent nanoprobe 1 with fluorescence emission in the NIR-II region is designed. In vitro and in vivo studies demonstrate that 1 has good photostability and the ability to efficiently inhibit the growth of tumor with minimal side effects. It also improves the fluorescent imaging quality and signal-to-noise ratio for cancer theranostics. This study provides an opportunity for further design of NIR-II theranostic anticancer agents for future biomedical applications.

Inspired by glucose-sensitive ion channels, herein we describe a biomimetic glucose-enantiomer-driven ion gate via the introduction of the chiral pillar[6]arene-based host–guest systems into the artificial nanochannels. The chiral nanochannels show a high chiral-driven ionic gate for glucose enantiomers and can be switched “off” by d-glucose and be switched “on” by l-glucose. Remarkably, the chiral nanochannel also exhibited a good reversibility toward glucose enantiomers. Further research indicates that the switching behaviors differed due to the differences in binding strength between chiral pillar[6]arene and glucose enantiomers, which can lead to the different surface charge within nanochannel. Given these promising results, the studies of chiral-driven ion gates may not only give interesting insight for the research of biological and pathological processes caused by glucose-sensitive ion channels, but also help to understand the origin of the high stereoselectivity in life systems.