Photodecomposition of ferrocenedicarboxylic acid in methanol to form an electroactive infinite coordination polymer and its application in bioelectrochemistry

Protein-driven interaction enhanced electrochemiluminescence biosensor of hydrogen-bonded biohybrid organic frameworks for sensitive immunoassay of disease markers

The oriented design of reticular materials as emitters can significantly enhance the sensitivity of electrochemiluminescence (ECL) sensing analysis for disease markers. However, due to the structural fragility of hydrogen bonds, relational research on hydrogen-bonded organic frameworks (HOFs) has not been thoroughly conducted. Additionally, the modulation of luminescence behavior through HOFs has been rarely reported. In view of this, hydrogen-bonded biohybrid organic frameworks (HBOFs) were synthesized and recruited for ECL immunoassay applications. HBOFs was easily prepared using 6,6',6″,6‴-(pyrene-1,3,6,8-tetrayl)tetrakis(2-naphthoic acid) as linkers via bovine serum albumin (BSA) activated hydrogen-bonded cross-linking. The material exhibited good fluorescence emission characteristics. And the highly ordered topological structure and molecular motion limitation mediated by BSA overcome aggregation-caused quenching and generate strong aggregation induced emission, expressing hydrogen-bond interaction enhanced ECL (HIE-ECL) activity with the participation of tri-n-propylamine. Furthermore, a sandwich immunosensor was constructed employing cobalt-based metal-phenolic network (CMPN) coated ferrocene nanoparticles (FNPs) as quenchers (CMPN@FNPs). Signal closure can be achieved by annihilating the excited state through electron transfer from both CMPN and FNPs. Using a universal disease marker, carcinoembryonic antigen, as the analysis model, the signal-off sensor obtained a detection limit of 0.47 pg/mL within the detection range of 1 pg/mL - 50 ng/mL. The synthesis and application of highly stable HBOFs triggered by proteins provide a reference for the development of new reticular ECL signal labels, and electron transfer model provides flexible solutions for more sensitive sensing analysis.

pH Switchable Nanozyme Platform for Healing Skin Tumor Wound Infected with Drug-Resistant Bacteria

Nanozymes capable of generating reactive oxygen species have recently emerged as promising treatments for wounds infected with drug-resistant bacteria, possessing a reduced possibility of inducing resistance. However, the therapeutic effect is limited by a shortage of endogenous oxy-substrates and undesirable off-target biotoxicity. Herein, a ferrocenyl coordination polymer (FeCP) nanozyme, featuring pH switchable peroxidase (POD)- and catalase (CAT)-like activity is incorporated with indocyanine green (ICG) and calcium peroxide (CaO2 ) to fabricate an H2 O2 /O2 self-supplying system (FeCP/ICG@CaO2 ) for precise treatment of bacterial infections. At the wound site, CaO2 reacts with water to generate H2 O2 and O2 . Acting as a POD mimic under an acidic bacterial microenvironment, FeCP catalyzes H2 O2 into hydroxyl radicals to prevent infection. However, FeCP switches to CAT-like activity in neutral tissue, decomposing H2 O2 into H2 O and O2 to prevent oxidative damage and facilitate wound healing. Additionally, FeCP/ICG@CaO2 shows photothermal therapy capability, as ICG can emit heat under near-infrared laser irradiation. This heat assists FeCP in fully exerting its enzyme-like activity. Thus, this system achieves an antibacterial efficiency of 99.8% in vitro for drug-resistant bacteria, and effectively overcomes the main limitations of nanozyme-based treatment assays, resulting in satisfactory therapeutic effects in repairing normal and special skin tumor wounds infected with drug-resistant bacteria.

Dual-infinite coordination polymer-engineered nanomedicines for dual-ion interference-mediated oxidative stress-dependent tumor suppression

Recently, nanomedicine design has shifted from simple nanocarriers to nanodrugs with intrinsic antineoplastic activities for therapeutic performance optimization. In this regard, degradable nanomedicines containing functional inorganic ions have blazed a highly efficient and relatively safe ion interference paradigm for cancer theranostics. Herein, given the potential superiorities of infinite coordination polymers (ICPs) in degradation peculiarity and functional integration, a state-of-the-art dual-ICP-engineered nanomedicine is elaborately fabricated via integrating ferrocene (Fc) ICPs and calcium-tannic acid (Ca-TA) ICPs. Thereinto, Fc ICPs, and Ca-TA ICPs respectively serve as suppliers of ferrous iron ions (Fe²⁺) and calcium ions (Ca²⁺). After the acid-responsive degradation of ICPs, released TA from Ca-TA ICPs facilitated the conversion of released ferric iron (Fe³⁺) from Fc ICPs into highly active Fe²⁺. Owing to the dual-path oxidative stress and neighboring effect mediated by Fe²⁺ and Ca²⁺, such a dual-ICP-engineered nanomedicine effectively induces dual-ion interference against triple-negative breast cancer (TNBC). Therefore, this work provides a novel antineoplastic attempt to establish ICP-engineered nanomedicines and implement ion interference-mediated synergistic therapy.

High-throughput chemiluminescence immunoassay based on Co2+/hemin synergistic catalysis for sensitive detection tetrabromobisphenol A bis(2-hydroxyethyl) ether in the environments

Here, a novel chemiluminescence (CL) immunoassay was fabricated for sensitive determination of tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE), one of typical tetrabromobisphenol A derivatives. At the indirectly competitive method, the synthesized PS@hemin@Co²⁺ was labelled by secondary antibody (Ab₂) instead of common natural enzymes, which showed excellent catalysis towards the decomposition of luminol-H₂O₂ for producing CL signal. Furthermore, the CL signal was greatly amplified owing to the synergistic catalysis of hemin and Co²⁺ in the detection system. Under the optimized conditions, the established method offered (i) low detection limit (LOD, 0.9 μg/L), which was almost 5 times lower than that using a conventional ELISA with the same antibody; (ii) a good linearity (1.6-14.3 μg/L); (iii) satisfactory accuracy and precision (recoveries, 89.67-125.33%; CV, 2.75-8.37%). The proposed CL immunoassay was applied for analysis of environmental samples from various sources collected from Jiangsu and Zhejiang province, China. And the detected concentrations were ranged in 2.4-3.7 μg/L in environmental waters and 1.8-2.4 ng/g (dry weight, dw) in soil samples, indicating great potential for trace TBBPA-DHEE detection from environmental samples.

A amperometric immunosensor for sensitive detection of circulating tumor cells using a tyramide signal amplification-based signal enhancement system

Herein, tyramide signal amplification (TSA)-based electrochemical immunosensor was exploited for highly sensitive detection of CTCs. In this immunosensor, the nucleolin-targeting aptamer AS1411 (CP) was used to specifically capture tumor cells, and a TSA-based signal enhancement system consisting of Pt NPs@HRP@CP composite as catalytic probe and tyramine functionalized infinite coordination polymer (ICPs@Tyr) as electroactive signal tag was applied to improve the detection sensitivity. Using HeLa cell as the model CTCs, after a sandwich reaction, CP-HeLa-Pt NPs@HRP@CP bioconjugates were formed on the electrode. Millions of ICPs@Tyr could be layer-by-layer deposited onto the target cell membrane by the catalysis of Pt NPs@HRP@CP. The developed immunorsensor could detect HeLa cell with a wide dynamic range from 2 to 2 × 10⁴ cells/mL and a detection limit of 2 cells/mL. Most importantly, the amperometric immunosensor was successfully applied to discriminate tumor cells from white blood cells, exhibiting high specificity and sensitivity. In conclusion, this work demonstrates that the TSA-based signal enhancement system might be a potential alternative tool for the electrochemical measurement of trace amounts of CTCs in clinical diagnosis.

Magneto-controlled flow-injection device for electrochemical immunoassay of alpha-fetoprotein on magnetic beads using redox-active ferrocene derivative polymer nanospheres

A new electrochemical immunosensing protocol by coupling with a magneto-controlled flow-through microfluidic device was developed for the sensitive detection of alpha-fetoprotein (AFP) on magnetic beads (MB) using ferrocene derivative polymer nanospheres (FDNP) as the electroactive mediators.

Construction of Multiple Switchable Sensors and Logic Gates Based on Carboxylated Multi-Walled Carbon Nanotubes/Poly(N,N-Diethylacrylamide)

In this work, binary hydrogel films based on carboxylated multi-walled carbon nanotubes/poly(N,N-diethylacrylamide) (c-MWCNTs/PDEA) were successfully polymerized and assembled on a glassy carbon (GC) electrode surface. The electroactive drug probes matrine and sophoridine in solution showed reversible thermal-, salt-, methanol- and pH-responsive switchable cyclic voltammetric (CV) behaviors at the film electrodes. The control experiments showed that the pH-responsive property of the system could be ascribed to the drug components of the solutions, whereas the thermal-, salt- and methanol-sensitive behaviors were attributed to the PDEA constituent of the films. The CV signals particularly, of matrine and sophoridine were significantly amplified by the electrocatalysis of c-MWCNTs in the films at 1.02 V and 0.91 V, respectively. Moreover, the addition of esterase, urease, ethyl butyrate, and urea to the solution also changed the pH of the system, and produced similar CV peaks as with dilution by HCl or NaOH. Based on these experiments, a 6-input/5-output logic gate system and 2-to-1 encoder were successfully constructed. The present system may lead to the development of novel types of molecular computing systems.

A label-free electrochemical immunosensor based on the novel signal amplification system of AuPdCu ternary nanoparticles functionalized polymer nanospheres

A sensitive label-free electrochemical immunosensor was designed using a novel signal amplification system for quantitative detecting hepatitis B surface antigen (HBsAg). Nitrogen-doped graphene quantum dots (N-GQDs) supported surfactant-free AuPdCu ternary nanoparticles (AuPdCu/N-GQDs), which featured with good conductivity and excellent catalytic properties for the reduction of hydrogen peroxide (H₂O₂), was synthesized by a simple and benign hydrothermal procedure. At the same time, the electroactive polymer nanospheres (PS) was synthesized by infinite coordination polymers of ferrocenedicarboxylic acid, which could play as carrier and electronic mediator to load AuPdCu/N-GQDs. The PS not only improved the ability to load antibodies because of the good biocompatibility, but also accelerated electron transport of the electrode interface attribute to plentiful ferrocene unit. Thus, the prepared AuPdCu/N-GQDs@PS has abilities of good biocompatibility, catalytic activity and electrical conductivity to be applied as transducing materials to amplify electrochemical signal in detection of HBsAg. Under optimal conditions, the fabricated immunosensor exhibited high sensitivity and stability in the detection of HBsAg. A linear relationship between current signals and the concentrations of HBsAg was obtained in the range from 10fg/mL to 50ng/mL and the detection limit of HBsAg was 3.3fg/mL (signal-to-noise ratio of 3). Moreover, the designed immunosensor with excellent selectivity, reproducibility and stability shows excellent performance in detection of human serum samples. Furthermore, this label-free electrochemical immunosensor has promising application in clinical diagnosis of HBsAg.

Design and synthesis of two novel functional metal–organic microcapsules; an investigation into ligand expansion effects on the metal–organic microcapsules' properties

Effects of ligand expansion on the size, morphology and loading capacity of tetrazole-based metal–organic microcapsules.

Novel photochromic infinite coordination polymer particles derived from a diarylethene photoswitch

A novel infinite coordination polymer (DAE-ICP) based on zinc nitrite and a diarylethene photoswitch, with reversible photochromic properties in solution and the solid state upon applying photostimuli, was synthesized and characterized by FT-IR, EDX, FE-SEM and FE-TEM.

A novel label-free amperometric immunosensor for carcinoembryonic antigen based on Ag nanoparticle decorated infinite coordination polymer fibres

In this article, for the first time, a novel, high-yield and template-free method for the synthesis of Ag nanoparticle decorated thionine/infinite coordination polymer (AgNP/THI/ICP) fibres is proposed. The thionine can be adsorbed to the AgNP/THI/ICP fibres by π-conjugation and act as the redox probe. The AgNP/THI/ICP fibres not only favor the immobilization of antibody but also facilitate the electron transfer. It is found that the AgNP/THI/ICP fibres can be designed to act as a sensitive label-free electrochemical immunosensor for carcinoembryonic antigen (CEA) determination. Under the optimized conditions, the linear range of the proposed immunosensor is estimated to be from 50 fg/mL to 100 ng/mL and the detection limit is estimated to be 0.5 fg/mL at a signal-to-noise ratio of 3, respectively. The prepared immunosensor for detection of CEA shows high sensitivity, reproducibility and stability. Our study demonstrates that the proposed immunosensor has also been used to determine CEA successfully in diluted blood samples.

An ionogel composite including copolymer nanowires for disposable electrochemiluminescent sensor configurations

Aniline derivatives such as luminol and benzidines can be electropolymerized for the preparation of electrochemiluminescent sensors.