A Piperazine Linked Rhodamine-BODIPY FRET-based Fluorescent Sensor for Highly Selective Pd2+ and Biothiol Detection.

A class of rhodamine-based fluorescent sensors for the selective and sensitive detection of Pd2+ metal ions in aqueous media has been developed. A rhodamine-based sensor PMS and a rhodamine-BODIPY Förster resonance energy transfer (FRET)-pair sensor PRS have been incorporated with a piperazine linker and an O-N-S-N podand ligand for specific recognition of Pd2+ ion. Both probes displayed colorimetric and fluorescent ratiometric changes when exposed to Pd2+ , due to their spirolactam rings opening and restoring rhodamine conjugation. PRS is highly selective to Pd2+ over 22 other metal ions, showing a 0.6-fold ratiometric difference at I600nm /I515nm . Additionally, the lactam ring in Pd2+ coordinated PRS-Pd could be switched back to the closed form in the presence of various thiols, providing a "red-green traffic light" detection mechanism between red and green emission. Furthermore, PRS showed excellent cell viability and was successfully employed to image Pd2+ and the PRS-Pd complex ensemble could interchangeably detect biothiols including glutathione (GSH) in A549 human lung cancer cells.

Rapid synthesis of bismuth-organic frameworks as selective antimicrobial materials against microbial biofilms.

Antibiotic resistance is a global public health threat, and urgent actions should be undertaken for developing alternative antimicrobial strategies and approaches. Notably, bismuth drugs exhibit potent antimicrobial effects on various pathogens and promising efficacy in tackling SARS-CoV-2 and related infections. As such, bismuth-based materials could precisely combat pathogenic bacteria and effectively treat the resultant infections and inflammatory diseases through a controlled release of Bi ions for targeted drug delivery. Currently, it is a great challenge to rapidly and massively manufacture bismuth-based particles, and yet there are no reports on effectively constructing such porous antimicrobial-loaded particles. Herein, we have developed two rapid approaches (i.e., ultrasound-assisted and agitation-free methods) to synthesizing bismuth-based materials with ellipsoid- (Ellipsoids) and rod-like (Rods) morphologies respectively, and fully characterized physicochemical properties. Rods with a porous structure were confirmed as bismuth metal-organic frameworks (Bi-MOF) and aligned with the crystalline structure of CAU-17. Importantly, the formation of Rods was a 'two-step' crystallization process of growing almond-flake-like units followed by stacking into the rod-like structure. The size of Bi-MOF was precisely controlled from micro-to nano-scales by varying concentrations of metal ions and their ratio to the ligand. Moreover, both Ellipsoids and Rods showed excellent biocompatibility with human gingival fibroblasts and potent antimicrobial effects on the Gram-negative oral pathogens including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum. Both Ellipsoids and Rods at 50 â€‹µg/mL could disrupt the bacterial membranes, and particularly eliminate P. gingivalis biofilms. This study demonstrates highly efficient and facile approaches to synthesizing bismuth-based particles. Our work could enrich the administration modalities of metallic drugs for promising antibiotic-free healthcare.

In situ redox-oxidation polymerization for magnetic core-shell nanostructure with polydopamine-encapsulated-Au hybrid shell.

This work reports a facile one-step method for the fabricating Fe3O4@Au/polydopamine sandwich-like core-shell nanostructure, in which the Au/polydopamine (Au/PDA) hybrid shell is obtained via an in situ redox-oxidation polymerization between the HAuCl4 and dopamine. The content of Au nanocrystals, shell thickness, and particle sizes are tunable by varying the experimental parameters. Intriguingly, this general method can be applied for different functional nanostructures such as the ß-FeOOH@Au/PDA, SiO2@Au/PDA, and CNT@Au/PDA nanocomposites. A possible formation mechanism is proposed and it is found that the surface interaction plays a key role in determining the final nanostructure. The as-prepared Fe3O4@Au/PDA exhibited eminent catalytic activity on the reduction of 4-nitrophenol. Since the external PDA shell prevents the Au nanocrystals from leaching during the reduction, the cycling activity has been maintained as high as 95% after seven times of catalytic reaction.