Search

Multifunctional bioimaging probes based on metal clusters have multiple characteristics of metal clusters and functional conjugates, and their development has broad application prospects in the fields of biomedical imaging and tumor diagnosis. However, current bioconjugation methods on metal clusters are time-consuming and have low reaction efficiency, which hinders the construction of bioimaging probes with multifunctional components. Here, we report a concise and promising design strategy to realize the simple and efficient introduction of functional conjugates through bioorthogonal reactions based on azido-functionalized metal clusters. Based on this strategy, taking the probe FA-CuC@BSA-Cy5 as an example, we demonstrated the design of a copper cluster-based multifunctional near-infrared (NIR) fluorescent probe and its real-time imaging application in vivo. Through the strain-promoted azide–alkyne cycloaddition (SPAAC) reaction, the tumor-specific targeting ligand folic acid (FA) and fluorophore (Cy5) can be chemically conjugated to azido-functionalized CuC@BSA-N3 quickly and efficiently under biocompatible conditions. The prepared probe showed numerous advantages of metal clusters, including good stability, ultra-small particle size and low toxicity and rapid renal clearance. At the same time, FA-modified FA-CuC@BSA-Cy5 can specifically target KB cells with high FR expression, and in vivo fluorescence imaging shows higher tumor accumulation. The construction of the azido functional metal cluster platform can be extended to various metal clusters with functional probes and prodrugs, thereby providing more promising candidates for future medical diagnoses. [ABSTRACT FROM AUTHOR]

A series of structurally novel anion receptors 3, 4, and 5 in which a ferrocene unit and a fluorescent moiety are linked to two imidazolium rings have been designed and prepared from 1,1′-bis(imidazolylmethyl)ferrocene. Their crystal structures revealed that these receptors are capable of incorporating anions such as PF6− and Br−. Consequently, the anion binding studies were carried out using various techniques including electrochemistry (CV and OSWV), fluorescence, UV-vis, and 1H NMR spectroscopy. All the receptors showed a special electrochemical response to the F− anion with a remarkable cathodic shift of more than 260 mV and displayed a unique selectivity for F− and AcO− anions with fluorescence enhancement over various other anions of present interest (Cl−, Br−, I−, HSO4−, H2PO4−). In addition, for receptor 5, obvious absorption changes were observed when the H2PO4− anion was added while other anions (F−, Cl−, Br−, I−, AcO−, HSO4−) showed only a minor influence on the UV-vis spectra. 1H NMR titrations demonstrated that receptors 3 and 4 can bind anions through (C–H)+⋯X− hydrogen bonds and showed strong affinity and high selectivity for the AcO− anion in acetonitrile. [ABSTRACT FROM AUTHOR]