Cu2O-directed in situ growth of Au nanoparticles inside HKUST-1 nanocages

Advances in plasmonic-based MOF composites, their bio-applications and perspectives in this field

INTRODUCTION

Nanomaterials have been used for bio-applications since the late 20st century. In an attempt to tailor and optimize their properties, and by extension their efficiency, composites have attracted considerable attention. In this regard, recent studies on plasmonic nanoparticles and metal-organic framework (NP@MOF) composites suggested these materials show great promise in this field.

AREAS COVERED

This review focused on the more recent scientific advances in the synthetic strategies to optimize plasmonic MOF nanocomposites currently available, as well as their bio-application, particularly as biosensors and therapy.

EXPERT OPINION

Plasmonic MOF nanocomposites have shown great potential as they combine the properties of both materials with proven efficiency in bio-application. On the one hand, nanoMOFs have proven their potential particularly as drug nanocarriers, owing to their exceptional porosity and tunability. On the other hand, plasmonic nanoparticles have been an asset for imaging and phototherapy. Different strategies have been reported to develop these nanocomposites, mainly including core-shell, encapsulation, and in situ reduction. In addition, advanced composite structures should be considered, such as mixed metal nanoparticles, hollow structures or the combination of several approaches. Specifically, plasmonic MOF nanocomposites prove to be attractive stimuli responsive drug delivery systems, phototherapeutic agents as well as highly sensitive biosensors.

Multifunctional MgO/HKUST-1 Composite for Capture, Catalysis, and Cyclic Cataluminescence Detection of Esters All-In-One to Rapidly Identify Scented Products

The integration of metallic oxide and metal-organic frameworks has attracted considerable attention as obtained composite materials because they show synergistic effects in applications of catalysis and sensing. Herein, we developed the hybrid MgO and HKUST-1 for efficient capture, catalysis, and cyclic cataluminescence (CCTL) detection of esters all-in-one to rapidly identify scented products. The multifunctional MgO/HKUST-1 composite with high CCTL activity was synthesized and characterized. The multifunctional MgO/HKUST-1 composite acts as an enrichment material for ester capture and serves as a catalyst, assisting the analyte to trigger multistage signals. The multistage signals of ester-containing scented products also satisfy the exponential decay equation with a certain τ-value. The τ-values obtained by the CCTL system were applied to identify the brands of essential oils. The working temperature served as the sensor element to obtain various τ-values. The τ-values constituted a digital code to label the different brands of cigarettes with the same aroma type. The multistage signals could be used to distinguish the origin regions of essential oils and tobacco. This work combines the CCTL strategy with the sample pretreatment, opening up a new direction to develop CCL and providing a new platform to rapidly identify ester-containing scented products.

Self-Assembly of a 3D Hollow BiOBr@Bi-MOF Heterostructure with Enhanced Photocatalytic Degradation of Dyes

Considering the flexibility, adjustable pore structure, and abundant active sites of metal-organic frameworks (MOFs), rational design and fine control of the MOF-based hetero-nanocrystals is a highly important and challenging subject. In this work, self-assembly of a 3D hollow BiOBr@Bi-MOF microsphere was fabricated through precisely controlled dissociation kinetics of the self-sacrificial template (BiOBr) for the first time, where the residual quantity of BiOBr and the formation of Bi-MOF were carefully regulated by changing the reaction time and the capability of coordination. Meanwhile, the hollow microstructure was formed in BiOBr@Bi-MOF through the Oswald ripening mechanism to separate photogenerated electron-hole pairs and increase the adsorption capacity of Bi-MOF for dyes, which significantly enhanced the photocatalytic degradation efficiency of RhB from 56.4% for BiOBr to 99.4% for the optimal BiOBr@Bi-MOF microsphere. This research broadens the selectivity of semiconductor/MOF hetero-nanocrystals with reasonable design and flexible synthesis.

Sensitive detection of streptomycin in milk using a hybrid signal enhancement strategy of MOF-based bio-bar code and target recycling

A MOF-based bio-bar code material was synthesized and firstly applied to develop an electrochemical streptomycin (STR) aptasensor. By using MOF-based bio-bar code and enzyme-assisted target recycling for dual-signal amplification, highly sensitive detection of STR was achieved. The sensing surface was simply fabricated by immobilizing a mixed monolayer of thiolated cDNA/aptamer duplexes (dsDNA) and 6-mercapto-1-hexanol (MCH) on the gold nanoparticle modified screen printed carbon electrode (Au/SPCE). The presence of target STR caused highly efficient removal of the aptamers from dsDNA assisted by Exo I enzyme. Then MOF-based bio-bar codes were backfilled to achieve the adsorption of electroactive Ru(NH₃)₆³⁺ (RuHex) on electrode surface. The electrochemical signal of the surface-confined RuHex was used for quantitation. The analytical performance for STR was satisfactory with a wide linear range of 0.005-150 ng mL^-1, a low detection limit of 2.6 pg mL^-1 and a good selectivity towards other three antibiotics. Moreover, the application of this aptasensor for determination of STR in real milk samples was also realized. With these merits, this dual-signal amplification assay might provide one of the effective ways for food safety monitoring.

Hollow porous Cu–Au particles with high catalytic activity for the reduction of 4-nitrophenol

A Cu-based bimetallic hollow structure can be effectively used to enhance the selective oxidation and electrocatalytic activity of a catalyst and to reduce its cost.

Metal–organic frameworks meet metal nanoparticles: synergistic effect for enhanced catalysis

This review highlights recent advances in the hybridization of metal–organic frameworks and metal nanoparticles for their synergistically enhanced catalysis.