Manipulation of Transmembrane Transport by Synthetic K + Ionophore Depsipeptides and Its Implications in Glucose‐Stimulated Insulin Secretion in β‐Cells

Universal and Naked-Eye Diagnostic Platform for Emetic Bacillus cereus Based on RPA-Assisted CRISPR/Cas12a

Emetic Bacillus cereus (B. cereus), which can cause emetic food poisoning and in some cases even fulminant liver failure and death, has aroused widespread concern. Herein, a universal and naked-eye diagnostic platform for emetic B. cereus based on recombinase polymerase amplification (RPA)-assisted CRISPR/Cas12a was developed by targeting the cereulide synthetase biosynthetic gene (cesB). The diagnostic platform enabled one-pot detection by adding components at the bottom and cap of the tube separately. The visual limit of detection of RPA-CRISPR/Cas12a for gDNA and cells of emetic B. cereus was 10-2 ng μL-1 and 102 CFU mL-1, respectively. Meanwhile, it maintained the same sensitivity in the rice, milk, and cooked meat samples even if the gDNA was extracted by simple boiling. The whole detection process can be finished within 40 min, and the single cell of emetic B. cereus was able to be recognized through enrichment for 2-5 h. The good specificity, high sensitivity, rapidity, and simplicity of the RPA-assisted CRISPR/Cas12a diagnostic platform made it serve as a potential tool for the on-site detection of emetic B. cereus in food matrices. In addition, the RPA-assisted CRISPR/Cas12a assay is the first application in emetic B. cereus detection.

Photosensitizers Based on Bichromophoric Dyads Combining Ru(II)-Polypyridyl Complexes and Dissymmetric Perylene Monoimide Derivatives: The Nontrivial Role of Ligand Substitution

The covalent modification of Ru(II) polypyridyl complexes (RPCs) with organic chromophores is a powerful strategy to obtain metal-based photosensitizer agents (PSs) with improved performance for application in photodynamic therapy (PDT). In this respect, perylene-imides are of particular interest due to their rich chemical-physical repertoire, and it is therefore quite surprising that their combination with RPCs has been poorly considered so far. Herein, we report on the photophysical behavior of two newly synthesized RPCs bearing a perylene monoimide appendant (PMI-Ad). Differently from the majority of RPCs-perylene-imides dyads, these chromophores are dissymmetric and are tethered to the metal centers through a single C-C bond in the 3- or 5-position of 1,10-phenanthroline (Ru-3PMI-Ad and Ru-5PMI-Ad). Both compounds show excellent singlet oxygen photosensitizing activity, with quantum yields reaching >90% in the case of Ru-3PMI-Ad. A combined spectroscopic and theoretical analysis, also involving transient absorption and luminescence lifetime measurements, demonstrates that both compounds undergo intersystem crossing on a very fast time scale (tens of picoseconds) and with high efficiency. Our results further demonstrate that the increased electron delocalization between the metal center and the PMI-Ad chromophore observed for Ru-3PMI-Ad additionally contributes to increase the singlet oxygen quantum yields by prolonging the lifetime of the triplet state.

Artificial transmembrane potassium transporters: designs, functions, mechanisms and applications

Potassium channels represent the most prevalent class of ion channels, exerting regulatory control over numerous vital biological processes, including muscle contraction, neurotransmitter release, cell proliferation, and apoptosis. The seamless integration of astonishing functions into a sophisticated structure, as seen in these protein channels, inspires the chemical community to develop artificial versions, gearing toward simplifying their structure while replicating their key functions. In particular, over the past ten years or so, a number of elegant artificial potassium transporters have emerged, demonstrating high selectivity, high transport efficiency or unprecedented transport mechanisms. In this review, we will provide a detailed exposition of these artificial potassium transporters that are derived from a single molecular backbone or self-assembled from multiple components, with their respective structural designs, channel functions, transport mechanisms and biomedical applications thoroughly reviewed.

Engineered DNAzyme Enables Homogeneous Detection of Cereulide via Polychromic Fluorescence Modality

Cereulide, the exotoxin of emetic Bacillus cereus, has garnered considerable attention due to its capacity to produce foodborne poisonings and great chemical stability. Herein, a G-quadruplex-hemin DNAzyme-based biosensor was developed to detect cereulide in the homogeneous solution. Due to the special ring structure and high affinity to K+, cereulide can be attracted and intercalated into the G-quadruplex; thus, the properties of the G4 DNAzyme can be altered. The melting temperature (Tm) of the G4 DNAzyme in the presence or absence of cereulide was 58.75 and 50.10 °C, respectively, proving the intercalation of cereulide into the G4 DNAzyme. By using the polychromic fluorescence modality of CdTe quantum dots and o-phenylenediamine to assess the variation in the catalytic activity of the DNAzyme, the intercalation of cereulide had bidirectional effects in G4 DNAzyme-mediated reactions, showing that the fluorescence intensity of CdTe quantum dots displayed a linear relationship with the concentration of cereulide from 0.16 to 40 μg/mL with the limit of detection (LOD) of 0.10 μg/mL, while the fluorescence intensity of DAP exhibited a linear relationship with the concentration of cereulide from 0.02 to 40 μg/mL with the LOD of 0.01 μg/mL. It will be a perspective step of controlling cereulide as a hazardous material in food or the environment.

Natural-product-based fluorescent probes: recent advances and applications

Fluorescent probes are attractive tools for biology, drug discovery, disease diagnosis, and environmental analysis. In bioimaging, these easy-to-operate and inexpensive probes can be used to detect biological substances, obtain detailed cell images, track in vivo biochemical reactions, and monitor disease biomarkers without damaging biological samples. Over the last few decades, natural products have attracted extensive research interest owing to their great potential as recognition units for state-of-the-art fluorescent probes. This review describes representative natural-product-based fluorescent probes and recent discoveries, with a particular focus on fluorescent bioimaging and biochemical studies.

Recent Advances in Bioactive Artificial Ionophores

Several life-threatening diseases, also known as 'Channelopathies' are linked to irregularities in ion transport proteins. Significant research efforts have fostered the development of artificial transport systems that facilitates to restore the functions of impaired natural transport proteins. Indeed, a few of these artificial ionophores demonstrate the rare combination of transmembrane ion transport and important biological activity, offering early promises of suitability in 'channel replacement therapy'. In this review, structural facets and functions of both cationophores and anionophores are discussed. Ionophores that are toxic to various bacteria and yeast, could be exploited as antimicrobial agent. Nevertheless, few non-toxic ionophores offer the likelihood of treating a wide range of genetic diseases caused by the gene mutations. In addition, their ability to disrupt cellular homeostasis and to alter lysosomal pH endow ionophores as promising candidates for cancer treatment. Overall, critically outlining the advances in artificial ionophores in terms of in vitro ion transport, possible modes of action and biological activities enables us to propose possible future roadmaps in this research area.

Biomedical Implants with Charge-Transfer Monitoring and Regulating Abilities

Transmembrane charge (ion/electron) transfer is essential for maintaining cellular homeostasis and is involved in many biological processes, from protein synthesis to embryonic development in organisms. Designing implant devices that can detect or regulate cellular transmembrane charge transfer is expected to sense and modulate the behaviors of host cells and tissues. Thus, charge transfer can be regarded as a bridge connecting living systems and human-made implantable devices. This review describes the mode and mechanism of charge transfer between organisms and nonliving materials, and summarizes the strategies to endow implants with charge-transfer regulating or monitoring abilities. Furthermore, three major charge-transfer controlling systems, including wired, self-activated, and stimuli-responsive biomedical implants, as well as the design principles and pivotal materials are systematically elaborated. The clinical challenges and the prospects for future development of these implant devices are also discussed.

Influence of core extension and side chain nature in targeting G-quadruplex structures with perylene monoimide derivatives

A structure-activity relationship (SAR) study in terms of G-quadruplex binding ability and antiproliferative activity of six fluorescent perylenemonoimide (PMIs) derivatives is reported. A positive charge seems to be the key to target G4. This study also reveals the importance of the element substitution in the potential biological activity of PMIs, being the polyethylene glycol (PEG) chains in the peri position responsible for their antiproliferative activity. Among them, the cationic PMI6 with two PEG chains is the most promising compound since its fluorescence is enhanced in the presence of G-quadruplex structures. Moreover, PMI6 binds to the human telomeric G-quadruplex hTelo with high affinity and displays a high antiproliferative potential towards HeLa (cervical adenocarcinoma), A549 (lung adenocarcinoma) and A2780 (ovarian adenocarcinoma) cells. Its fate can be followed inside cells thanks to its fluorescent properties: the compound is found to accumulate in the mitochondria.