Highly sensitive and selective demethylase FTO detection using a DNAzyme-mediated CRISPR/Cas12a signal cascade amplification electrochemiluminescence biosensor with C-CN/PCNV heterojunction as emitter

Fat mass and obesity-associated protein (FTO) has gained attention as the first RNA N6-methyladenosine (m6A) modification eraser due to its overexpression being associated with various cancers. In this study, an electrochemiluminescence (ECL) biosensor for the detection of demethylase FTO was developed based on DNAzyme-mediated CRISPR/Cas12a signal cascade amplification system and carboxylated carbon nitride nanosheets/phosphorus-doped nitrogen-vacancy modified carbon nitride nanosheets (C-CN/PCNV) heterojunction as the emitter. The biosensor was constructed by modifying the C-CN/PCNV heterojunction and a ferrocene-tagged probe (ssDNA-Fc) on a glassy carbon electrode. The presence of FTO removes the m6A modification on the catalytic core of DNAzyme, restoring its cleavage activity and generating activator DNA. This activator DNA further activates the trans-cleavage ability of Cas12a, leading to the cleavage of the ssDNA-Fc and the recovery of the ECL signal. The C-CN/PCNV heterojunction prevents electrode passivation and improves the electron-hole recombination, resulting in significantly enhanced ECL signal. The biosensor demonstrates high sensitivity with a low detection limit of 0.63 pM in the range from 1.0 pM to 100 nM. Furthermore, the biosensor was successfully applied to detect FTO in cancer cell lysate and screen FTO inhibitors, showing great potential in early clinical diagnosis and drug discovery.

Ratiometric electrochemical aptasensor based on split aptamer and Au-rGO for detection of aflatoxin M1

A novel ratiometric electrochemical aptasensor based on split aptamer and Au-reduced graphene oxide (Au-rGO) nanomaterials was proposed to detect aflatoxin M1 (AFM1). In this work, Au-rGO nanomaterials were coated on the electrode through the electrodeposition method to increase the aptamer enrichment. We split the aptamer of AFM1 into 2 sequences (S1 and S2), where S1 was immobilized on the electrode due to the Au-S bond, and S2 was tagged with methylene blue (MB) and acted as a response signal. A complementary strand to S1 (CS1) labeled with ferrocene (Fc) was introduced as another reporter. In the presence of AFM1, CS1 was released from the electrode surface due to the formation of the S1-AFM1-S2 complex, leading to a decrease in Fc and an increase in the MB signal. The developed ratiometric aptasensor exhibited a linear range of 0.03 μg L-1 to 2.00 μg L-1, with a detection limit of 0.015 μg L-1 for AFM1 detection. The ratiometric aptasensor also showed a linear relationship from 0.2 μg L-1 to 1.00 μg L-1, with a detection limit of 0.05 μg L-1 in natural milk after sample pretreatment, indicating the successful application of the developed ratiometric aptasensor. Our proposed strategy provides a new way to construct aptasensors with high sensitivity and selectivity.

Universal nanocomposite coating with antifouling and redox capabilities for electrochemical affinity biosensing in complex biological fluids

Electrochemical affinity biosensors have the potential to facilitate the development of multiplexed point-of-care diagnostics in complex biological fluids. However, their commercial viability has been hindered by challenges such as electrode biofouling and the lack of inherent redox properties. To address this unmet need, we have developed a universal nanocomposite coating which is unique in its ability to not only allow oriented conjugation of the biorecognition element but also specific detection directly in complex biological fluids like serum and urine owing to its built-in antifouling and redox capabilities, thus improving suitability for point of care testing. This multifunctional coating comprises a 3D porous crosslinked bovine serum albumin matrix for oriented conjugation and antifouling properties with embedded graphene nanosheets modified with amino-ferrocene for enhanced conductivity and mediator-free biosensing. The coating showed minimal signal degradation despite prolonged exposure to 1% bovine serum albumin, artificial urine and untreated human serum for up to 30 days. To demonstrate its utility, we fabricated and tested proof-of-concept electrochemical immunosensors for bladder cancer protein biomarkers, specifically interleukin-8 (IL-8) and vascular endothelial growth factor (VEGF). The practical feasibility was highlighted by the excellent sensitivity and specificity observed for IL-8 and VEGF with a limit of detection of 41 pg mL-1 and 67 pg mL-1, respectively. Consequently, this universal nanocomposite-based electrochemical biosensing platform can be extended to the point of care testing of a broad spectrum of biomarkers present in complex biological fluids, thus enabling reliable and early diagnostics.

Ferrocene-functionalized polydopamine film timely mediates M1-to-M2 macrophage polarization through adaptive wettability

Dynamical control of macrophage polarization from M1 (pro-inflammatory) to M2 (anti-inflammatory) at implant surfaces is essential for balancing innate immunity and tissue repair. In this aspect, the design of orthopedic implant that can response to inflammation microenvironment with transformation in surface properties has shown promising in timely driving M1-to-M2 macrophage transition. Considering excessive reactive oxygen species (ROS) contribute to macrophage M1 polarization and progression of inflammation, in this study, ferrocene modified polydopamine (PDA-Fc) films were deposited on plasma sprayed Ti coatings to endow the implants with ROS-responsive and -scavenging abilities. Plasma sprayed Ti (PST) coating and PDA modified PST coating (PST/PDA) served as control. The presence of PDA endowed PST/PDA and PST/PDA-Fc with free-radical scavenging abilities. Moreover, PST/PDA-Fc showed adaptive wettability as evidenced by increased hydrophilicity under H2O2 treatment. With respect to PST/PDA, PST/PDA-Fc exerted greater effects on inducing lipopolysaccharides-induced M1 macrophages to adopt M2-type macrophage phenotype, characterized by higher percentage of CD206-positive cells, increased cell elongation rate and higher expression level of anti-inflammatory cytokine arginase type 1. The results obtained in our study may provide a prospective approach for manipulating an appropriate immune response at implant surfaces.

A ferrocene-based hydrogel as flexible electrochemical biosensor for oxidative stress detection and antioxidation treatment

Real-time sensing of reactive oxygen species (ROS) and timely scavenging of excessive ROS in physiological environments are critically important in the diagnosis and prevention of ROS-related diseases. To solve the mismatch problem between conventional rigid ROS biosensors and biological tissues in terms of both modulus and composition, here, we present a flexible ferrocene-based hydrogel biosensor designed for oxidative stress detection and antioxidation treatment. The hydrogel was fabricated through a supramolecular assembly of ferrocene-grafted polyethylenimine (PEI-Fc), sodium alginate (SA), and polyvinyl alcohol (PVA). Multiple non-covalent interactions, including electrostatic interactions between PEI-Fc and SA, hydrophobic interactions and π-π stacking among ferrocene groups, and the PVA crystalline domain, synergistically improve the mechanical properties of the PVA/SA/PEI-Fc hydrogel. The flexible PVA/SA/PEI-Fc hydrogel biosensor exhibited a broad detection range for hydrogen peroxide (H2O2), from 0 to 120 μM, using the differential pulse voltammetry method. Furthermore, the hydrogel demonstrated effective ROS scavenging and oxygen generation performance, desirable biocompatibility, and satisfactory antibacterial activity, making it suitable for biological interfaces. In vitro studies revealed that the PVA/SA/PEI-Fc hydrogel could monitor H2O2 concentration in the proximity of inflammatory cells, and effectively scavenge ROS to protect cells from oxidative stress damage. This all-in-one multifunctional hydrogel, integrating both sensing and treatment functions, holds great promise for clinical applications in the diagnosis and management of ROS-related diseases.

Fluorescence/electrochemical dual-mode strategy for Golgi protein 73 detection based on molybdenum disulfide/ferrocene/palladium nanoparticles and nitrogen-doped graphene quantum dots

Golgi protein 73 (GP73) is a new serum marker associated with early diagnosis and postoperative assessment of hepatocellular carcinoma (HCC). Herein, an electrochemical/fluorescence dual-signal biosensor was designed for determination of GP73 based on molybdenum disulfide/ferrocene/palladium nanoparticles (MoS2-Fc-PdNPs) and nitrogen-doped graphene quantum dots (NGQDs). GP73 aptamer (Apt) was labeled with NGQDs to form the NGQDs-Apt fluorescence probe. MoS2-Fc-PdNPs served not only as the fluorescence quencher but also as electrochemical enhancer. The sensing platform (NGQDs-Apt/MoS2-Fc-PdNPs) was formed based on the fluorescence resonance energy transfer (FRET) mechanism. In the presence of GP73, the specific binding of NGQDs-Apt to GP73 interrupted FRET, restoring the fluorescence of NGQDs-Apt at λex/em = 348/438 nm and enhancing the oxidation current of Fc in MoS2-Fc-PdNPs at 0.04 V through differential pulse voltammetry (DPV). Under the optimal conditions, the DPV current change and fluorescence recovery have a good linear relationship with GP73 concentration from 1.00 to 10.0 ng/mL. The calibration equation for the fluorescence mode was Y1 = (0.0213 ± 0.00127)X + (0.0641 ± 0.00448) and LOD was 0.812 ng/mL (S/N = 3). The calibration equation of the electrochemical mode was Y2 = (3.41 ± 0.111)X + (1.62 ± 0.731), and LOD of 0.0425 ng/mL (S/N = 3). The RSDs of fluorescence mode and electrochemical mode after serum detection were 1.62 to 5.21% and 0.180 to 6.62%, respectively. By combining the electrochemical and fluorescence assay, more comprehensive and valuable information for GP73 was provided. Such dual-mode detection platform shows excellent reproducibility, stability, and selectivity and has great application potential.

Antifungal and Antiparasitic Activities of Metallocene-Containing Fluconazole Derivatives

The search for new anti-infectives based on metal complexes is gaining momentum. Among the different options taken by researchers, the one involving the use of organometallic complexes is probably the most successful one with a compound, namely, ferroquine, already in clinical trials against malaria. In this study, we describe the preparation and in-depth characterization of 10 new (organometallic) derivatives of the approved antifungal drug fluconazole. Our rationale is that the sterol 14α-demethylase is an enzyme part of the ergosterol biosynthesis route in Trypanosoma and is similar to the one in pathogenic fungi. To demonstrate our postulate, docking experiments to assess the binding of our compounds with the enzyme were also performed. Our compounds were then tested on a range of fungal strains and parasitic organisms, including the protozoan parasite Trypanosoma cruzi (T. cruzi) responsible for Chagas disease, an endemic disease in Latin America that ranks among some of the most prevalent parasitic diseases worldwide. Of high interest, the two most potent compounds of the study on T. cruzi that contain a ferrocene or cobaltocenium were found to be harmless for an invertebrate animal model, namely, Caenorhabditis elegans (C. elegans), without affecting motility, viability, or development.

Redox-Active Ferrocene Quencher-Based Supramolecular Nanomedicine for NIR-II Fluorescence-Monitored Chemodynamic Therapy

Real-time monitoring of hydroxyl radical (⋅OH) generation is crucial for both the efficacy and safety of chemodynamic therapy (CDT). Although ⋅OH probe-integrated CDT agents can track ⋅OH production by themselves, they often require complicated synthetic procedures and suffer from self-consumption of ⋅OH. Here, we report the facile fabrication of a self-monitored chemodynamic agent (denoted as Fc-CD-AuNCs) by incorporating ferrocene (Fc) into β-cyclodextrin (CD)-functionalized gold nanoclusters (AuNCs) via host-guest molecular recognition. The water-soluble CD served not only as a capping agent to protect AuNCs but also as a macrocyclic host to encapsulate and solubilize hydrophobic Fc guest with high Fenton reactivity for in vivo CDT applications. Importantly, the encapsulated Fc inside CD possessed strong electron-donating ability to effectively quench the second near-infrared (NIR-II) fluorescence of AuNCs through photoinduced electron transfer. After internalization of Fc-CD-AuNCs by cancer cells, Fenton reaction between redox-active Fc quencher and endogenous hydrogen peroxide (H2 O2 ) caused Fc oxidation and subsequent NIR-II fluorescence recovery, which was accompanied by the formation of cytotoxic ⋅OH and therefore allowed Fc-CD-AuNCs to in situ self-report ⋅OH generation without undesired ⋅OH consumption. Such a NIR-II fluorescence-monitored CDT enabled the use of renal-clearable Fc-CD-AuNCs for efficient tumor growth inhibition with minimal side effects in vivo.

Ferrocene crosslinked and functionalized chitosan microspheres towards bio-based Fenton-like system for the removal of organic pollutants

Dye-containing wastewater treatment has been a major long-term global challenge. For this purpose, a novel bio-based microspheres (CS-FC) with high specific surface area (63.24 m2·g-1) and nano-channels (17.95 nm) was prepared using chitosan as the framework and ferrocene as a crosslinking active group. CS-FC not only has the ability to rapidly enrich methyl orange (MO) through hydrogen-bonding and electrostatic attraction, but also almost completely degrades it in the presence of H2O2/K2S2O8 through a synergistic radical/non-radical mechanism under the activating effect of ferrocene. Without H2O2/K2S2O8, the maximum MO adsorption capacity of CS-FC is in the range 871-1050 mg·g-1, and conforms to a Langmuir isothermal model with pseudo-second-order kinetics. In the presence of H2O2/K2S2O8, the removal of MO dramatically increased from 32 % to nearly 100 % after incubation for 60 min, due to the simultaneous formation of highly reactive 1O2 and ·OH. The significant contribution from 1O2 endowed CS-FC/H2O2/K2S2O8 with high universality for degrading various organic pollutants (including azo dyes and antibiotics), a wide pH window (2-8), and low sensitivity to co-existing ions. Such cost-effective, recyclable porous bio-based microspheres are suitable for heterogeneous Fenton-like catalysis in organic wastewater treatment that rely on synergistic radical/non-radical reaction pathways.

Preparation of new organo-ruthenium(II) complexes and their nucleic acid/albumin binding efficiency and in vitro cytotoxicity studies

Hetero-bimetallic ruthenium(II) complexes (PRAFIZ and PRBFIZ) containing acetyl ferrocene (AFIZ)/benzoyl ferrocene isonicotinic hydrazone ligands (BFIZ) were synthesized and characterized by various spectral and analytical techniques. The structure of acetyl ferrocene isonicotinic hydrazone (AFIZ) and the complex PRBFIZ was confirmed by X-ray crystallography. The hydrazide ligands coordinated in a bidentate monobasic fashion using their N1 hydrazinic nitrogen and enolic oxygen atoms. The binding interactions of the ligands and complexes were examined using Calf-Thymus DNA (CT-DNA) and bovine serum albumin (BSA). Scanning Electron Microscopic (SEM) experiments clarified the efficient binding interaction of the ligands and complexes with BSA. The results of in vitro cytotoxicity studies on MDA-MB-261 breast cancer cells and A549 human lung cancer cells and cell morphological analysis results through staining assays clearly indicated the cytotoxic nature of the complexes.

Anticancer Metallocenes and Metal Complexes of Transition Elements from Groups 4 to 7

With the progression in the field of bioinorganic chemistry, the role of transition metal complexes as the most widely used therapeutics is becoming a more and more attractive research area. The complexes of transition metals possess a great variety of attractive pharmacological properties, including anticancer, anti-inflammatory, antioxidant, anti-infective, etc., activities. Transition metal complexes have proven to be potential alternatives to biologically active organic compounds, especially as antitumor agents. The performance of metal coordination compounds in living systems is anticipated to differ generally from the action of non-metal-containing drugs and may offer unique diagnostic and/or therapeutic opportunities. In this review, the rapid development and application of metallocenes and metal complexes of elements from Groups 4 to 7 in cancer diagnostics and therapy have been summarized. Most of the heavy metals discussed in the current review are newly discovered metals. That is why the use of their metal-based compounds has attracted a lot of attention concerning their organometallic and coordination chemistry. All of this imposes more systematic studies on their biological activity, biocompatibility, and toxicity and presupposes further investigations.

Highly sensitive biosensor for specific miRNA detection based on cascade signal amplification and magnetic electrochemiluminescence nanoparticles

Herein, magnetic electrochemiluminescence (ECL) nanoparticle Fe3O4@PtPd/Ru(bpy)32+ had been synthesized then been coupled with CRISPR/Cas13a system and Zn2+ dependent DNAzyme to design a novel ECL biosensor for specific detection of microRNA-145 (miRNA). The synthesized multifunctional magnetic nanoluminescent materials Fe3O4@PtPd/Ru(bpy)32+ not only load Ru(bpy)32+ to provide ECL signals, but also can quickly achieve separation and enrichment from complex matrices. In addition, ferrocene (Fc) was used as a quencher in the Ru(bpy)32+/tripropylamine (TPA) system. Fc was modified on DNA bound to Fe3O4@PtPd. Benefited from the highly specific recognition ability of CRISPR/Cas13a, the target miRNA induces CRISPR/Cas13a trans-cleavage to trigger the Zn2+-dependent DNAzyme cyclic cleavage to realize the dual signal amplification. DNA modified by Fc was split by target miRNA-induced cleaving, and then magnetic separation was performed to keep Fc away from the surface of the nanoparticles. Thus, the enhanced ECL signal was obtained to detect miRNA-145. Under optimized conditions, the prepared sensor showed a wide linear range (1 fM to 1 nM) and a low limit of detection (LOD) down to 0.41 fM. Furthermore, it shows excellent selectivity and good reproducibility. The proposed ECL platform has huge potential applications in the development of various sensitive sensors for detecting the other miRNA.

Development of a fluorescent sensor based on TPE-Fc and GSH-AuNCs for the detection of organophosphorus pesticide residues in vegetables

A novel dual-signal fluorescent sensor was developed for detecting organophosphorus pesticides (OPs). It relies on the catalytic activities of acetylcholinesterase (AChE) and choline oxidase (ChOx) to generate hydrogen peroxide (H2O2) through the conversion of acetylcholine (ACh) to choline·H2O2 then oxidizes ferrocene-modified tetraphenylethylene (TPE-Fc) to its oxidized state (TPE-Fc+), resulting in enhanced cyan fluorescence due to aggregation. Simultaneously, ferrocene oxidation generates hydroxyl radicals (•OH), causing a decrease in orange fluorescence of glutathione-synthesized gold nanoclusters (GSH-AuNCs). The presence of OPs restricts AChE activity, reducing H2O2 production. Increasing OPs concentration leads to decreased cyan fluorescence and increased orange fluorescence, enabling visual OPs detection. The sensor has a linear dynamic range of 10-2000 ng/mL with a detection limit of 2.05 ng/mL. Smartphone-based color identification and a WeChat mini program were utilized for rapid OPs analysis with successful outcomes.

A CRISPR-Cas12a-based electrochemical biosensor for the detection of microphthalmia-associated transcription factor

A novel electrochemical biosensor that combines the CRISPR-Cas12a system with a gold electrode is reported for the rapid and sensitive detection of microphthalmia-associated transcription factor (MITF). The biosensor consists of a gold electrode modified with DNA1, which contains the target sequence of MITF and is labeled with ferrocene, an electroactive molecule. The biosensor also includes hairpin DNA, which has a binding site for MITF and can hybridize with helper DNA to form a double-stranded complex that activates CRISPR-Cas12a. When MITF is present, it binds to hairpin DNA and prevents its hybridization with helper DNA, thus inhibiting CRISPR-Cas12a activity and preserving the DPV signal of ferrocene. When MITF is absent, hairpin DNA hybridizes with helper DNA and activates CRISPR-Cas12a, which cleaves DNA1 and releases ferrocene, thus reducing the DPV signal. The biosensor can detect MITF with high sensitivity (with an LOD of 8.14 fM), specificity, and accuracy in various samples, such as cell nuclear extracts and human serum. The biosensor can also diagnose and monitor melanocyte-related diseases and melanin production. This work provides a simple, fast, sensitive, and cost-effective biosensor for MITF detection and a valuable tool for applications in genetic testing, disease diagnosis, and drug screening.

Copolymerization of ethylene and isoprene via silicon bridge metallocene [rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2] catalyst: A new way to control the composition and microstructure of copolymers

The copolymerization of ethylene (E) with isoprene (Ip) was performed catalyzed by a symmetrical catalyst exhibiting a silicon bridge [rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 with the combination of borate/TIBA activator. The effect of cocatalyst, Ip concentration, and polymerization temperature on the activity, molecular weight (Mw), distribution (MWD), comonomer composition, chain structure (regio- and stereoselectivity), and resulting side reactions were logically addressed. Gel-permeation chromatography (GPC) was used to characterize the Mw and polydispersity, while nuclear magnetic resonance (NMR) was employed for the chain structure of the polymers. The catalytic activity was significantly lower by increasing the Ip concentration in the feed, and the isoprene content in resulting polymers was lower under the reaction condition, leading to higher activity. Insertion of isoprene units in polymer structure demonstrates the higher regioselectivity for the 3,4 connections than the 1,4 connections and is expected to be a high-resistance polymer against acids. The MWD presented monomodal even with a higher concentration (1.44 mol/L) and did not appear as low Mw peaks of Ip. The Mw was higher with a broader MWD when purely TIBA was used as a cocatalyst, and it significantly reduced and presented a narrowed MWD with TEA in the cocatalyst. The higher efficiency of the catalyst for the higher insertion of Ip (C=C double bond) effectively modifies the polymer backbone. It is expected to be a promising candidate for easily degradable and favorable solutions for solving environmental problems caused by PE. wastes.

Cancer Nanobombs Delivering Artoxplatin with a Polyigniter Bearing Hydrophobic Ferrocene Units Upregulate PD-L1 Expression and Stimulate Stronger Anticancer Immunity

Poor immunogenicity seriously hampers the broader implementation of antitumor immunotherapy. Enhanced immunogenicity capable of achieving greater antitumor immunity is urgently required. Here, a novel polymer that contains hydrophobic ferrocene (Fc) units and thioketal bonds in the main chain, which further delivered a prodrug of oxaliplatin and artesunate, i.e., Artoxplatin, to cancer cells is described. This polymer with Fc units in the nanoparticle can work as a polyigniter to spark the peroxide bonds in Artoxplatin and generate abundant reactive oxygen species (ROS) to kill cancers as nanobombig for cancer therapy. Moreover, ROS can trigger the breakdown of thioketal bonds in the polymer, resulting in the biodegradation of the polymer. Importantly, nanobombig can facilitate the maturation of dendritic cells and promote the activation of antitumor immunity, through the enhanced immunogenic cell death effect by ROS generated in situ. Furthermore, metabolomics analysis reveals a decrease in glutamine in nanobombig -treated cancer cells, resulting in the upregulation of programmed death ligand 1 (PD-L1). Consequently, it is further demonstrated enhanced tumor inhibitory effects when using nanobombig combined with anti-PD-L1 therapy. Overall, the nanosystem offers a rational design of an efficient chemo-immunotherapy regimen to promote antitumor immunity by improving tumor immunogenicity, addressing the key challenges cancer immunotherapy faced.

An exact and vigorous kinetic Monte Carlo simulation to determine the properties of bimodal HDPE synthesized with a dual-site metallocene catalyst

A vigorous and progressed Monte Carlo strategy was developed to precisely simulate the ethylene and 1-butene copolymerization within the presence of hydrogen by dual-site metallocene catalyst. The results showed up that the ethylene and 1-butene consumption rates at the second catalyst site were approximately 5 times higher than at the first site, and hydrogen transfer rates at the first catalyst site were over 3 times more rapid than at the second site. It was found that the most elevated molar percentage of 1-butene inside the copolymers synthesized from the second site was around 12% and within the copolymers gotten from the first site was around 2%. At a steady hydrogen concentration, with 8 times increase in the 1-butene concentration within the initial feed, the overall weight average molecular weight (M‾w) and an overall number average molecular weight (M‾n) extended by approximately 50% and 40%, respectively. Besides, at a consistent 1-butene concentration, with 8 times increase in the concentration of hydrogen, M‾w and M‾n diminished by approximately 18% and 22%, separately. Due to the synthesis of two groups of chains with distinct molecular weights, the overall dispersity (Đ) was slightly higher than the dispersity resulting from each catalyst site (1.5-2.1). With increasing 1-butene concentrations, the overall bimodal molecular weight distribution (MWD) widened, and the peak sizes grew smaller and moved towards higher molecular weights. As hydrogen concentration increased, peaks became taller and move toward shorter chain lengths. It was observed that the first site created chain lengths between 102 and 103 while the second site generated chain lengths between 102 and 106. As the concentration of 1-butene was increased in the initial feed, the number of short chain branching per 1000 carbon atoms (SCB/1000C) increased from 10 to 50. Compared to the first site, there were 5 times as many SCBs at the chains produced from the second site. By diminishing the ratio of ethylene to 1-butene, the melt index (MI) tended towards smaller numbers (0.2≤MI≤2). With an increase in the ratio of ethylene to 1-butene and ethylene to hydrogen, the weight fraction of crystals raised from 67.4 to 69.5% and diminished from 71 to 69.5%, respectively. At last, increasing the temperature led to a diminish in molecular weight, a narrowing of the bimodal MWD, an increment within the thickness and weight fraction of crystals, and an increment within the density of HDPE.

Reversing Ferroptosis Resistance in Breast Cancer via Tailored Lipid and Iron Presentation

Ferroptotic cancer therapy is promising in many scenarios where traditional cancer therapies show a poor response. However, certain types of cancers lack the long-chain acyl-CoA synthetase 4 (ACSL4), a key modulator of ferroptosis, resulting in therapy resistance and tumor relapse. Because ACSL4 is in charge of the synthesis of ferroptotic lipids (e.g., arachidonoylphosphatidylethanolamine/PE-AA), we postulated that direct delivery of PE-AA may reverse ferroptosis resistance induced by ACSL4 deficiency. To further increase the ferroptosis sensitivity, we employed the ferrocene-bearing polymer micelles to co-load PE-AA with an FDA-approved redox modulator, auranofin (Aur), targeting the thioredoxin reductase. The presence of ferrocene enabled triggered cargo release and iron production, which can sensitize ferroptosis by boosting autoxidation-mediated PE-AA peroxidation. The micellar system could impair redox homeostasis and induce lipid peroxidation in ACSL4-deficient MCF-7 cells. Moreover, the tailored micelles potently induced ferroptosis in MCF-7 tumors in vivo, suppressed tumor growth, and increased the mice's survival rate. The current work provides a facile means for reversing the ferroptosis resistance in ACSL4-deficient tumors.

Trisulfide Bond-Mediated Molecular Phototheranostic Platform for "Activatable" NIR-II Imaging-Guided Enhanced Gas/Chemo-Hypothermal Photothermal Therapy

Tumor microenvironment (TME)-triggered phototheranostic platform offers a feasible strategy to improve cancer diagnosis accuracy and minimize treatment side effects. Developing a stable and biocompatible molecular phototheranostic platform for TME-activated second near-infrared (NIR-II) fluorescence imaging-guided multimodal cascade therapy is a promising strategy for creating desirable anticancer agents. Herein, a new NIR-II fluorescence imaging-guided activatable molecular phototheranostic platform (IR-FEP-RGD-S-S-S-Fc) is presented for actively targeted tumor imaging and hydrogen sulfide (H2 S) gas-enhanced chemodynamic-hypothermal photothermal combined therapy (CDT/HPTT). It is revealed for the first time that the coupling distance between IR-FE and ferrocene is proportional to the photoinduced electron transfer (PET), and the aqueous environment is favorable for PET generation. The part of Cyclic-RGDfK (cRGDfk) peptides can target the tumor and benefit the endocytosis of nanoparticles. The high-concentration glutathione (GSH) in the TME will separate the fluorescence molecule and ferrocene by the GSH-sensitive trisulfide bond, realizing light-up NIR-II fluorescence imaging and a cascade of trimodal synergistic CDT/HPTT/gas therapy (GT). In addition, the accumulation of hydroxyl radicals (•OH) and down-regulation of glutathione peroxidase 4 (GPX4) can produce excessive harmful lipid hydroperoxides, ultimately leading to ferroptosis.

The Renaissance of Ferrocene-Based Electrocatalysts: Properties, Synthesis Strategies, and Applications

The fascinating electrochemical properties of the redox-active compound ferrocene have inspired researchers across the globe to develop ferrocene-based electrocatalysts for a wide variety of applications. Advantages including excellent chemical and thermal stability, solubility in organic solvents, a pair of stable redox states, rapid electron transfer, and nontoxic nature improve its utility in various electrochemical applications. The use of ferrocene-based electrocatalysts enables control over the intrinsic properties and electroactive sites at the surface of the electrode to achieve specific electrochemical activities. Ferrocene and its derivatives can function as a potential redox medium that promotes electron transfer rates, thereby enhancing the reaction kinetics and electrochemical responses of the device. The outstanding electrocatalytic activity of ferrocene-based compounds at lower operating potentials enhances the specificity and sensitivity of reactions and also amplifies the response signals. Owing to their versatile redox chemistry and catalytic activities, ferrocene-based electrocatalysts are widely employed in various energy-related systems, molecular machines, and agricultural, biological, medicinal, and sensing applications. This review highlights the importance of ferrocene-based electrocatalysts, with emphasis on their properties, synthesis strategies for obtaining different ferrocene-based compounds, and their electrochemical applications.

A Multifunctional Covalent Organic Framework Nanozyme for Promoting Ferroptotic Radiotherapy against Esophageal Cancer

Radiotherapy is inevitably accompanied by some degree of radiation resistance, which leads to local recurrence and even therapeutic failure. To overcome this limitation, herein, we report the room-temperature synthesis of an iodine- and ferrocene-loaded covalent organic framework (COF) nanozyme, termed TADI-COF-Fc, for the enhancement of radiotherapeutic efficacy in the treatment of radioresistant esophageal cancer. The iodine atoms on the COF framework not only exerted a direct effect on radiotherapy, increasing its efficacy by increasing X-ray absorption, but also promoted the radiolysis of water, which increased the production of reactive oxygen species (ROS). In addition, the ferrocene surface decoration disrupted redox homeostasis by increasing the levels of hydroxyl and lipid peroxide radicals and depleting intracellular antioxidants. Both in vitro and in vivo experiments substantiated the excellent radiotherapeutic response of TADI-COF-Fc. This study demonstrates the potential of COF-based multinanozymes as radiosensitizers and suggests a possible treatment integration strategy for combination oncotherapy.

Double bipolar electrode electrochemiluminescence color switch for food-borne pathogens detection

Color-switch electrochemiluminescence (ECL) sensing platform based on a dual-bipolar electrode (D-BPE) is reported in this work. The D-BPE was composed of a cathode filled with buffer and two anodes filled with [Ru(bpy)3]2+-TPrA and luminol-H2O2 solutions, respectively. Both anodes were modified with capture DNA and served as ECL reporting platforms. After introducing ferrocene-labeled aptamer (Fc-aptamer) on both anodes, the ECL emission signal of the [Ru(bpy)3]2+ was difficult to be observed (anode 1), while luminol emitted a strong and visible ECL signal (anode 2). Ferrocene (Fc) did not only prevent the oxidation of [Ru(bpy)3]2+ due to its lower oxidation potential, its oxidation product Fc+ also quenched the [Ru(bpy)3]2+ ECL through efficient energy transfer. For luminol, Fc+ catalyzes the accelerated formation of the excited-state of the luminol anion radical, which leads to the enhancement of the luminol ECL. In the presence of food-borne pathogens, the aptamer was assembled with them, leading to the leaving of Fc from the surface of the D-BPE anodes. The ECL intensity of [Ru(bpy)3]2+ was enlarged, meanwhile, the blue emission signal of luminol became weakened. By self-calibrating the ratio of the two signals, 1-106 CFU mL-1 food-borne pathogenic bacteria can be sensitively detected with a detection limit of 1 CFU mL-1. Ingeniously, the color-switch biosensor can be used to detect S. aureus, E. coli and S. typhimurium by assembling the corresponding aptamers onto the D-BPE anodes.

Ferrocene/ β-cyclodextrin based supramolecular nanogels as theranostic systems

A supramolecular redox responsive nanogel (NG) with the ability to sense cancer cells and loaded with a releasing therapeutic agent was synthesized using hostguest interactions between polyethylene glycol-grafted-β-cyclodextrin and ferrocene boronic acid. Cyclic voltammetry matched with other spectroscopy and microscopy methods provided strong indications regarding host-guest interactions and formation of the NG. Moreover, the biological properties of the NG were evaluated using fluorescence silencing, confocal laser scanning microscopy, and cell toxicity assays. Nanogel with spherical core-shell architecture and 100-200 nm sized nanoparticles showed high encapsulation efficiency for doxorubicin (DOX) and luminol (LU) as therapeutic and sensing agents. High therapeutic and sensing efficiencies were manifested by complete release of DOX and dramatic quenching of LU fluorescence triggered by 0.05 mM H2O2 (as an ROS component). The NGs showed high ROS sensitivity. Taking advantage of a high loading capacity, redox sensitivity, and biocompatibility, the NGs can be used as strong theranostic systems in inflammation-associated diseases.

Efficient Three-Dimensional DNA Nanomachine Guided by a Robust Tetrahedral DNA Nanoarray Structure for the Rapid and Ultrasensitive Electrochemical Detection of Matrix Metalloproteinase 2

Herein, a giant-sized DNA nanoarray was subtly assembled by two kinds of independent tetrahedral DNA structures as the DNA track for a multi-armed three-dimensional (3D) DNA nanomachine to perform signal transduction and amplification efficiently, which was developed as an electrochemical biosensor for the rapid and ultrasensitive detection of matrix metalloproteinase 2 (MMP-2). Impressively, in contrast to conventional DNA walkers with inefficiency, which walked on random DNA tracks composed of a two-dimensional (2D) probe or a one-dimensional (1D) single-stranded (ss)DNA probe, the multi-armed 3D DNA nanomachine from exonuclease III (Exo III) enzyme-assisted target recycling amplification would be endowed with faster reaction speed and better walking efficiency because of the excellent rigidity and orderliness of the tetrahedral DNA nanoarray structure. Once the hairpin H3-label with the signal substance ferrocene (Fc) was added to the modified electrode surface, the multi-armed 3D DNA nanomachine would be driven to move along the well-designed nanoarray tracks by toehold-mediated DNA strand displacement, resulting in most of the ferrocene (Fc) binding to the electrode surface and a remarkable increase in electrochemical signals within 60 min. As a proof of concept, the prepared biosensor attained a low detection limit of 11.4 fg/mL for the sensitive detection of the target MMP-2 and was applied in Hela and MCF-7 cancer cell lysates. As a result, this strategy provided a high-performance sensing platform for protein detection in tumor diagnosis.

Design, Synthesis, and Evaluation of Biological Activity of Ferrocene-Ispinesib Hybrids: Impact of a Ferrocenyl Group on the Antiproliferative and Kinesin Spindle Protein Inhibitory Activity

With the aim to combine more than one biologically-active component in a single molecule, derivatives of ispinesib and its (S) analogue were prepared that featured ferrocenyl moieties or bulky organic substituents. Inspired by the strong kinesin spindle protein (KSP) inhibitory activity of ispinesib, the compounds were investigated for their antiproliferative activity. Among these compounds, several derivatives demonstrated significantly higher antiproliferative activity than ispinesib with nanomolar IC50 values against cell lines. Further evaluation indicated that the antiproliferative activity is not directly correlated with their KSP inhibitory activity while docking suggested that several of the derivatives may bind in a manner similar to ispinesib. In order to investigate the mode of action further, cell cycle analysis and reactive oxygen species formation were investigated. The improved antiproliferative activity of the most active compounds may be assigned to synergic effects of various factors such as KSP inhibitory activity due to the ispinesib core and ability to generate ROS and induce mitotic arrest.

Ferrozoles: Ferrocenyl derivatives of letrozole with dual effects as potent aromatase inhibitors and cytostatic agents

In the treatment of hormone-dependent cancers, aromatase inhibitors (AI) are receiving increased attention due to some undesirable effects such as the risk of endometrial cancer and thromboembolism of SERMs (selective estrogen receptor modulators). Letrozole is the most active AI with 99% aromatase inhibition. Unfortunately, this compound also exhibits some adverse effects such as hot flashes and fibromyalgias. Therefore, there is an urgent need to explore new types of AIs that retain the same-or even increased-antitumor ability. Inspired by the letrozole structure, a set of new derivatives has been synthesized that include a ferrocenyl moiety and different heterocycles. The derivative that contains a benzimidazole ring, namely compound 6, exhibits a higher aromatase inhibitory activity than letrozole and it also shows potent cytostatic behavior when compared to other well-established aromatase inhibitors, as demonstrated by dose-response, cell cycle, apoptosis and time course experiments. Furthermore, 6 promotes the inhibition of cell growth in both an aromatase-dependent and -independent fashion, as indicated by the study of A549 and MCF7 cell lines. Molecular docking and molecular dynamics calculations on the interaction of 6 or letrozole with the aromatase binding site revealed that the ferrocene moiety increases the van der Waals and hydrophobic interactions, thus resulting in an increase in binding affinity. Furthermore, the iron atom of the ferrocene fragment can form a metal-acceptor interaction with a propionate fragment, and this results in a stronger coupling with the heme group-a possibility that is consistent with the strong aromatase inhibition of 6.

Ferrocene-based nitroheterocyclic sulfonylhydrazones: design, synthesis, characterization and trypanocidal properties

A series of new ferrocenyl nitroheterocyclic sulfonylhydrazones (1a-4a and 1b-2b) were prepared by the reaction between formyl (R = H) or acetyl (R = CH3) nitroheterocyclic precursors [4/5-NO2(C5H2XCOR), where X = O, S)] and ferrocenyl tosyl hydrazine [(η5-C5H5)Fe(η5-C5H4SO2-NH-NH2)]. All compounds were characterized by conventional spectroscopic techniques. In the solid state, the molecular structures of compounds 1a, 2b, and 3a were determined by single-crystal X-ray diffraction. The compounds showed an E-configuration around the C=N moiety. Evaluation of trypanocidal activity, measured in vitro against the Trypanosoma cruzi and Trypanosoma brucei strains, indicated that all organometallic tosyl hydrazones displayed activity against both parasite species with a higher level of potency toward T. brucei than T. cruzi. Moreover, the biological evaluation showed that the 5-nitroheterocyclic derivatives were more efficient trypanocidal agents than their 4-nitroheterocyclic counterparts.

An "on-off-on" electrochemiluminescence aptasensor based on a self-enhanced luminophore for ochratoxin A detection

A highly selective and sensitive "on-off-on" electrochemiluminescence (ECL) aptasensor based on a self-enhanced luminophore was developed for the detection of ochratoxin A (OTA). Specifically, polyethyleneimine functionalized multi-walled carbon nanotubes decorated with gold nanoparticles (AuNPs-PEI-MWCNTs) were used as the electrode matrix to accelerate electron transfer and provide a favorable microenvironment for self-enhanced luminophore loading and ECL signal enhancement. In addition, black phosphorus quantum dots (BPQDs) were used as co-reactants of the ECL reagent tris (2,2'-bipyridyl) ruthenium(II) (Ru(bpy)32+) in ECL experiments, and the reaction mechanism was investigated. The self-enhanced luminophore Ru@SiO2-BPQDs was obtained by encapsulating Ru(bpy)32+ in silica (SiO2) nanoparticles and then combining it with BPQDs through electrostatic interaction. In conventional ECL systems, the emitter and its co-reactants reacted via the inter-nanoparticle pathway, leading to long distance electron transfer. However, the electron transfer distance in the self-enhanced luminophore was significantly shortened due to the intra-nanoparticle electron transfer pathway because BPQDs and oxidized Ru(bpy)32+ were bound within one nanoparticle, thereby improving ECL efficiency to achieve the first "switch-on" state. Then, the luminophore was quenched using ferrocenes (Fc) modified on an aptamer to achieve the "switch-off" state. Finally, OTA was specifically identified by the adapter, causing Fc to be released from the sensor interface, restoring the ECL intensity to achieve the second "switch-on" state. Under optimal conditions, the aptasensor exhibited good sensitivity, stability, and reproducibility, with a linear detection range from 0.1 to 320 ng/mL and a detection limit of 0.03 ng/mL. The novel ECL aptasensor provided a common analytical tool for the detection of mycotoxins and other small molecules.

In Situ Construction of Ferrocene-Containing Membrane-Bound Nanofibers for the Redox Control of Cancer Cell Death and Cancer Therapy

Precise manipulation of cancer cell death by harnessing reactive oxygen species (ROS) is a promising strategy to defeat malignant tumors. However, it is quite difficult to produce active ROS with spatial precision and regulate their biological outcomes. We succeed here in selectively generating short-lived and lipid-reactive hydroxyl radicals (•OH) adjacent to cancer cell membranes, successively eliciting lipid peroxidation and ferroptosis. DiFc-K-pY, a phosphorylated self-assembling precursor that consists of two branched Fc moieties and interacts specifically with epidermal growth factor receptor, can in situ produce membrane-bound nanofibers and enrich ferrocene moieties on cancer cell membranes in response to alkaline phosphatase. Within the acidic tumor microenvironment, DiFc-K-pY nanofibers efficiently convert tumoral H2O2 to active •OH around the target cell membranes via Fenton-like reactions, leading to lipid peroxidation and ferroptosis with good cellular selectivity. Our strategy successfully prevents tumor progression with acceptable biocompatibility through intratumoral administration.

Strategic Design and Synthesis of Ferrocene Linked Porous Organic Frameworks toward Tunable CO2 Capture and Energy Storage

This work focuses on porous organic polymers (POPs), which have gained significant global attention for their potential in energy storage and carbon dioxide (CO2) capture. The study introduces the development of two novel porous organic polymers, namely FEC-Mel and FEC-PBDT POPs, constructed using a simple method based on the ferrocene unit (FEC) combined with melamine (Mel) and 6,6'-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) (PBDT). The synthesis involved the condensation reaction between ferrocenecarboxaldehyde monomer (FEC-CHO) and the respective aryl amines. Several analytical methods were employed to investigate the physical characteristics, chemical structure, morphology, and potential applications of these porous materials. Through thermogravimetric analysis (TGA), it was observed that both FEC-Mel and FEC-PBDT POPs exhibited exceptional thermal stability. FEC-Mel POP displayed a higher surface area and porosity, measuring 556 m2 g-1 and 1.26 cm3 g-1, respectively. These FEC-POPs possess large surface areas, making them promising materials for applications such as supercapacitor (SC) electrodes and gas adsorption. With 82 F g-1 of specific capacitance at 0.5 A g-1, the FEC-PBDT POP electrode has exceptional electrochemical characteristics. In addition, the FEC-Mel POP showed remarkable CO2 absorption capabilities, with 1.34 and 1.75 mmol g-1 (determined at 298 and 273 K; respectively). The potential of the FEC-POPs created in this work for CO2 capacity and electrical testing are highlighted by these results.

Washing-Free Electrochemiluminescence Biosensor for the Simultaneous Determination of N6 Methyladenosines Incorporating a Tri-Double Resolution Strategy

We propose a novel washing-free electrochemiluminescence (ECL) biosensor for the simultaneous detection of two types of N6 methyladenosines-RNAs (m6A-RNAs), which are potential cancer biomarkers, on the basis of binding-induced DNA strand displacement (BINSD). The biosensor integrated a tri-double resolution strategy that combined spatial and potential resolution, hybridization and antibody recognition, and ECL luminescence and quenching. The biosensor was fabricated by separately immobilizing two ECL reagents (gold nanoparticles/g-C3N4 nanosheets and ruthenium bipyridine derivative/gold nanoparticles/Nafion) and the capture DNA probe on the two sections of glassy carbon electrode. As a proof of concept, m6A-Let-7a-5p and m6A-miR-17-5p were chosen as model analytes, while m6A antibody-DNA3/ferrocene-DNA4/ferrocene-DNA5 was designed as an m6A-binding probe and DNA6/DNA7 was designed as a hybridization probe with DNA3 to release the quenching probes ferrocene-DNA4/ferrocene-DNA5. The recognition process led to the quenching of the ECL signals from both probes via BINSD. The proposed biosensor has the advantage of being washing-free. The ECL methods using the fabricated ECL biosensor with the designed probes exhibited a low detection limit of 0.03 pM for two m6A-RNAs and high selectivity. This work reveals that this strategy is promising for developing an ECL method for the simultaneous detection of two m6A-RNAs. The proposed strategy could be expanded to develop the analytical methods for the simultaneous detection of other RNA modifications by changing the antibody and hybridization probe sequences.

Enhanced arsenite removal from water using zirconium-ferrocene MOFs coupled with peroxymonosulfate:oxidation and multi-sites adsorption mechanism

The efficient removal of arsenite (As(III)) poses a significant challenge to traditional water treatment technologies due to its high toxicity and mobility. In this work, multifunctional Zirconium-Ferrocene Metal Organic Framework (ZrFc-MOF) fabricated with redox-active 1,1-ferrocene dicarboxylic acid ligands and Zr⁴⁺ precursors were elaborated to achieve remarkably enhanced As(III) removal via activation by peroxymonosulfate (PMS). The adsorption affinity coefficient increased from 0.097 to 2.035 L mg^-1 and the maximum adsorption capacity increased from 59.79 to 111.34 mg g^-1 compared with that without PMS. Besides the conventional homogeneous PMS oxidation and the following adsorption through Zr-O clusters of ZrFc-MOFs, the enhanced As(III) removal synergistic combines the oxidation mechanism of As(III) by reactive oxygen species (•OH, SO₄^•-, O₂^•- and ¹O₂) formed in Ferrocene (Fc) activating PMS process with the simultaneous formed extra adsorption sites of Ferrocenium (Fc⁺). PMS also help ZrFc-MOF to avoid destruction in harsh alkaline condition, making the effluent in this advanced treatment meet the World Health Organization (WHO) threshold of 10 μg L^-1 over a wide range of initial pH (2-11) with high selectivity and durability. These results indicate that this novel Fc-based MOFs activating PMS system has potential applicability for As(III) in oxidation and selectively capturing in the water environment.

Atomic layer encapsulation of ferrocene into zeolitic imidazolate framework-67 for efficient arsenic removal from aqueous solutions

Arsenic (As(V))-contaminated water is a major global threat to human health and the ecosystem because of its enormous toxicity, carcinogenicity, and high distribution in water streams. Thus, As(V) removal in the environmental samples has received considerable attention. Till now, numerous metal-organic framework materials have been used for the As(V) removal from the aqueous medium, but low As(V) removal and instability of the adsorbents have severely cut off their practical applications. In this study, a ferrocene-encapsulated zeolitic imidazolate framework-67 (Fc-ZIF-67) material was synthesized for As(V) removal from an aqueous solution at neutral pH using a simple solution mixing process. The ferrocene encapsulation provides water-stable and structural defects to ZIF-67. Furthermore, the ferrocene molecule and imidazole linker can enhance As(V) adsorption via both chemisorption and physisorption. The novel Fc-ZIF-67 adsorbent exhibited superior As(V) adsorption performance with an adsorption capacity of 63.29 mg/g at neutral pH. The Langmuir and Freundlich isotherm models were also used to analyze adsorption behavior.

NIR-II Luminescent and Multi-Responsive Rare Earth Nanocrystals for Improved Chemodynamic Therapy

Chemodynamic therapy (CDT) based on the Fe²⁺-mediated Fenton reaction can amplify intracellular oxidative stress by producing toxic •OH. However, the high-dose need for Fe²⁺ delivery in tumors and its significant cytotoxicity to normal tissues set a challenge. Therefore, a controllable delivery to activate the Fenton reaction and enhance Fe²⁺ tumor accumulation has become an approach to solve this conflict. Herein, we report a rare-earth-nanocrystal (RENC)-based Fe²⁺ delivery system using light-control techniques and DNA nanotechnology to realize programmable Fe²⁺ delivery. Ferrocenes, the source of Fe²⁺, are modified on the surface of RENCs through pH-responsive DNAs, which are further shielded by a PEG layer to elongate blood circulation and "turn off" the cytotoxicity of ferrocene. The up-/down-conversion dual-mode emissions of RENCs endow the delivery system with both capabilities of diagnosis and delivery control. The down-conversion NIR-II fluorescence can locate tumors. Consequently, up-conversion UV light spatiotemporally activates the catalytic activity of Fe²⁺ by shedding off the protective PEG layer. The exposed ferrocene-DNAs not only can "turn on" Fenton catalytic activity but also respond to tumor acidity, driving cross-linking and enhanced Fe²⁺ enrichment in tumors by 4.5-fold. Accordingly, this novel design concept will be inspiring for developing CDT nanomedicines in the future.

Inflammatory Cell-Inspired Cascade Nanozyme Induces Intracellular Radical Storm for Enhanced Anticancer Therapy

Manipulating intracellular levels of reactive oxygen and nitrogen species (RONS) is of great potential for cancer treatment. Inspired by the natural mechanism of a radical storm in inflammatory cells via activated and regulatable biocatalysis, the authors herein report a self-powered nanozyme that can enable RONS production in tumor cells via cascade reactions. The nanozymes are constructed via glucose oxidase (GOx)-templated inverse microemulsion polymerization from acrylamide, arginine-acrylamide, ferrocene-acrylate, and N,N'-bis(acryloyl)cystamine, followed by surface coating with hyaluronic acid. After targeted delivery into cancer cells, the nanozymes are dissociated by intracellular glutathione to release GOx, which decomposed glucose to generate gluconic acid and H₂ O₂ . Under such acidified conditions, H₂ O₂ efficiently oxidized pendant arginine residues to produce nitric oxide , transformed into a highly toxic hydroxyl radical and superoxide anion via ferrocene-mediated Fenton reaction and Haber-Weiss cycle, and simultaneously generated peroxynitrite anion via reaction between NO and ·O₂ ^- , thus provoking the RONS radical storm to effectively eradicate A549 tumor cells both in vitro and in vivo. This nature-inspired enzyme-chemical dynamic therapy may provide a promising modality for anti-cancer treatment.

A versatile platform for colorimetric, fluorescence and photothermal multi-mode glyphosate sensing by carbon dots anchoring ferrocene metal-organic framework nanosheet

Concerns regarding pesticide residues have driven attempts to exploit accurate, prompt and straightforward approaches for food safety pre-warning. Herein, a nanozyme-mediated versatile platform with multiplex signal response (colorimetric, fluorescence and temperature) was proposed for visual, sensitive and portable detection of glyphosate (GLP). The platform was constructed based on a N-CDs/FMOF-Zr nanosensor that prepared by in situ anchoring nitrogen-doped carbon dots onto zirconium-based ferrocene metal-organic framework nanosheets. The N-CDs/FMOF-Zr possessed excellent peroxidase (POD)-like activity and thus could oxide colorless 3, 3', 5, 5'-tetramethylbenzidine (TMB) into a blue oxidized TMB (oxTMB) in presence of H₂O₂. Intriguingly, owing to the blocking effect triggered by multiple interaction between GLP and N-CDs/FMOF-Zr, its POD-like activity of the latter was remarkably suppressed, which can modulate the transformation of TMB into oxTMB, generating tri-signal responses of fluorescence enhancement, absorbance and temperature decrease. More significantly, the temperature mode can be facilely realized by a portable home-made mini-photothermal device and handheld thermometers. The proposed multimodal sensing was capable of providing sensitive results by fluorescence mode and simultaneously realized visual/portable testing by colorimetric and photothermal channels. Consequently, it exhibited more adaptability for practical applications, which can satisfy different testing requirements according to sensitivity and available instruments/meters, presenting a new horizon for exploiting multifunctional sensors.

Controllable synthesis of FeMn bimetallic ferrocene-based metal-organic frameworks to boost the catalytic efficiency for removal of organic pollutants

A series of FeMn bimetallic ferrocene-based metal-organic frameworks (FeMn-Fc-MOFs) with various molar ratios of Fe and Mn (1:9, 2:8, 4:6, 6:4) were successfully synthesized using a simple hydrothermal synthesis method and employed as an efficient activator on persulfate (PS) activation for water decontamination. Characterizations demonstrated that Fe and Mn were smoothly introduced into ferrocene-based MOFs and various molar ratios of Fe:Mn had some influence on crystallinity and surface structure of FeMn-Fc-MOFs. Within 120 min, Fe₄Mn₆-Fc-MOFs demonstrated the best catalytic activity among the different molar ratios, and acid orange 7(AO7) degradation rate was up to 92.0%. In addition, electrochemical experiments revealed that Fe₄Mn₆-Fc-MOFs possessed superior electron transfer capability than other FeMn-Fc-MOFs, leading to better catalytic performance. Moreover, quenching tests and electron paramagnetic resonance (EPR) detection indicated that hydroxyl radicals and sulfate radicals were both responsible for AO7 decomposition. Notably, the redox cycle of Fe(II)/Fe(III) and Mn(II)/Mn(IV) was discovered in the Fe₄Mn₆-Fc-MOFs/PS system, which was considered as the limiting process for the cleavage of the O-O bond in PS to generate active radicals. Ultimately, the Fe₄Mn₆-Fc-MOFs exhibits an excellent universality and good cycling stability for 5 continuous runs. This paper broadens the application of ferrocene-based MOFs on heterogeneous PS activation in environmental catalysis.

Combining bioinspired nanochannels with ferrocene doped MoS2 nanoplates: Application to ratiometric electrochemical detection of let-7a

Sensitive and accurate detection of tumor suppressor genes is vastly important to the related therapeutic research. Herein, a ratiometric electrochemical method for let-7a detection was established by integrating a ferrocene (Fc) doped MoS₂ nanoplates modified electrode into the nanochannels-based biosensing platform. The ratiometric signal was developed by the redox current of methylene blue (MB) which reflects the target recognition occurred into the nanochannels and the redox current of Fc which corrects the slight signal deviation caused by some analyte-independent factors. And thus, the ratio of peak current of MB and Fc (I_MB/I_Fc) measured at differential pulse voltammogram varied precisely with the increment of the concentration of let-7a incubated in the bioinspired nanochannels. The strategy of spherical DNAzyme induced deposition in nanochannels was utilized to further amplify the signal. Under optimal conditions, a wide linear dynamic range of 50 aM to 10 pM spanning five orders of magnitude was obtained. The developed electrochemical method, with attomole level of detection limit, was successfully applied to the determination of let-7a in human serum and tumor cells. The study not only offers a new route for reliable nucleic acid detection, but also provides an excellent opportunity to extend the application of the two-dimensional transition-metal dichalcogenides.

Ferrocene-Based Polymeric Nanoparticles Carrying Doxorubicin for Oncotherapeutic Combination of Chemotherapy and Ferroptosis

Mono-chemotherapy has significant side effects and unsatisfactory efficacy, limiting its clinical application. Therefore, a combination of multiple treatments is becoming more common in oncotherapy. Chemotherapy combined with the induction of ferroptosis is a potential new oncotherapy. Furthermore, polymeric nanoparticles (NPs) can improve the antitumor efficacy and decrease the toxicity of drugs. Herein, a polymeric NP, mPEG-b-PPLGFc@Dox, is synthesized to decrease the toxicity of doxorubicin (Dox) and enhance the efficacy of chemotherapy by combining it with the induction of ferroptosis. First, mPEG-b-PPLGFc@Dox is oxidized by endogenous H₂ O₂ and releases Dox, which leads to an increase of H₂ O₂ by breaking the redox balance. The Fe(II) group of ferrocene converts H₂ O₂ into ·OH, inducing subsequent ferroptosis. Furthermore, glutathione peroxidase 4, a biomarker of ferroptosis, is suppressed and the lipid peroxidation level is elevated in cells incubated with mPEG-b-PPLGFc@Dox compared to those treated with Dox alone, indicating ferroptosis induction by mPEG-b-PPLGFc@Dox. In vivo, the antitumor efficacy of mPEG-b-PPLGFc@Dox is higher than that of free Dox. Moreover, the loss of body weight in mice treated mPEG-b-PPLGFc@Dox is lower than in those treated with free Dox, indicating that mPEG-b-PPLGFc@Dox is less toxic than free Dox. In conclusion, mPEG-b-PPLGFc@Dox not only has higher antitumor efficacy but it reduces the damage to normal tissue.

Electrochemiluminescence biosensor for DNA adenine methylation methyltransferase based on CRISPR/Cas12a trans-cleavage-induced dual signal enhancement

In this work, an electrochemiluminescence (ECL) biosensor with dual signal enhancement was constructed and used for DNA adenine methylation methyltransferase (Dam MTase) detection. At present of Dam MTase, restriction endonuclease (DPnI) cleaves hairpin DNA (HP) and releases the HP stem end as a single strand that can activate CRISPR/Cas12a trans-cleavage activity. Assisted by trans-cleavage, the distance between the signal quenching factor ferrocene (Fc) and the ECL signal unit increased, and the repulsion between the signal unit and the Indium Tin Oxides (ITO) electrode decreased. The above results resulted in an enhanced ECL signal. ECL intensity has a good linear relationship with the logarithm of Dam MTase concentration in the range of 5-70 U/mL with a detection limit of 23.4 mU/mL. The proposed biosensor was successfully utilized to detect of Dam MTase in serum samples.

The Phosphinate Group in the Formation of 2D Coordination Polymer with Sm(III) Nodes: X-ray Structural, Electrochemical and Mössbauer Study

A coordination polymer has been synthesized using ferrocene-based ligand-bearing phosphinic groups of 1,1'-ferrocene-diyl-bis(H-phosphinic acid)), and samarium (III). The coordination polymer's structure was studied by both single-crystal and powder XRD, TG, IR, and Raman analyses. For the first time, the Mössbauer effect studies were performed on ferrocenyl phosphinate and the polymer based on it. Additionally, the obtained polymer was studied by the method of cyclic and differential pulse voltammetry. It is shown that it has the most positive potential known among ferrocenyl phosphinate-based coordination polymers and metal-organic frameworks. Using the values of the oxidation potential, the polymer was oxidized and the ESR method verified the oxidized Fe(III) form in the solid state. Additionally, the effect of the size of the phosphorus atom substituent of the phosphinate group on the dimension of the resulting coordination compounds is shown.

Molecular Hybridization Strategy on the Design, Synthesis, and Structural Characterization of Ferrocene-N-acyl Hydrazones as Immunomodulatory Agents

Immunomodulatory agents are widely used for the treatment of immune-mediated diseases, but the range of side effects of the available drugs makes necessary the search for new immunomodulatory drugs. Here, we investigated the immunomodulatory activity of new ferrocenyl-N-acyl hydrazones derivatives (SintMed(141−156). The evaluated N-acyl hydrazones did not show cytotoxicity at the tested concentrations, presenting CC50 values greater than 50 µM. In addition, all ferrocenyl-N-acyl hydrazones modulated nitrite production in immortalized macrophages, showing inhibition values between 14.4% and 74.2%. By presenting a better activity profile, the ferrocenyl-N-acyl hydrazones SintMed149 and SintMed150 also had their cytotoxicity and anti-inflammatory effect evaluated in cultures of peritoneal macrophages. The molecules were not cytotoxic at any of the concentrations tested in peritoneal macrophages and were able to significantly reduce (p < 0.05) the production of nitrite, TNF-α, and IL-1β. Interestingly, both molecules significantly reduced the production of IL-2 and IFN-γ in cultured splenocytes activated with concanavalin A. Moreover, SintMed150 did not show signs of acute toxicity in animals treated with 50 or 100 mg/kg. Finally, we observed that ferrocenyl-N-acyl hydrazone SintMed150 at 100 mg/kg reduced the migration of neutrophils (44.6%) in an acute peritonitis model and increased animal survival by 20% in an LPS-induced endotoxic shock model. These findings suggest that such compounds have therapeutic potential to be used to treat diseases of inflammatory origin.

Mediator Microbial Biosensor Analyzers for Rapid Determination of Surface Water Toxicity

Microbial mediator biosensors for surface water toxicity determination make it possible to carry out an early assessment of the environmental object’s quality without time-consuming standard procedures based on standard test-organisms, and provide broad opportunities for receptor element modifying depending on the required operational parameters analyzer. Four microorganisms with broad substrate specificity and nine electron acceptors were used to form a receptor system for toxicity assessment. Ferrocene was the most effective mediator according to its high rate constant of interaction with the microorganisms (0.33 ± 0.01 dm3/(g × s) for yeast Saccharomyces cerevisiae). Biosensors were tested on samples containing four heavy metal ions (Cu2+, Zn2+, Pb2+, Cd2+), two phenols (phenol and p-nitrophenol), and three natural water samples. The «ferrocene- Escherichia coli» and «ferrocene-Paracoccus yeei, E. coli association» systems showed good operational stability with a relative standard deviation of 6.9 and 7.3% (14 measurements) and a reproducibility of 7 and 5.2% using copper (II) ions as a reference toxicant. Biosensor analysis with these systems was shown to highly correlate with the results of the standard method using Chlorella algae as a test object. Developed biosensors allow for a valuation of the polluted natural water’s impact on the ecosystem via an assessment of the influence on bacteria and yeast in the receptor system. The systems could be used in toxicological monitoring of natural waters.

Modeling Absolute Redox Potentials of Ferrocene in the Condensed Phase

Absolute thermodynamic quantities for critical chemical reactions are needed to determine the role of solvents and reactive environments in catalysis and electrocatalysis. Theoretical methods can provide such quantification but are often hindered by the innate complexity of electron correlation and dynamic relaxation of solvent environments. We present and validate a protocol for calculating the redox potentials of the ferrocene/ferrocenium redox pair in acetonitrile. Equation-of-motion and effective fragment potential (EFP) methods are used to characterize the adiabatic and vertical ionization potentials as well as the electron affinity processes. We benchmark molecular mechanics against the EFP model to show the differences in the ferrocene electronic polarizability in two redox states. Our best estimate of the redox potential (4.94 eV) agrees well with the experimental value (4.93 eV). This demonstrates the ability of modern computational methods to predict absolute redox potentials quantitatively and to quantify the correlation of dynamic effects, which underlie their origin.

Ionization of Decamethylmanganocene: Insights from the DFT-Assisted Laser Spectroscopy

Metallocenes represent one of the most important classes of organometallics with wide prospects for practical use in various fields of chemistry, materials science, molecular electronics, and biomedicine. Many applications of these metal complexes are based on their ability to form molecular ions. We report the first results concerning the changes in the molecular and electronic structure of decamethylmanganocene, Cp*₂Mn, upon ionization provided by the high-resolution mass-analyzed threshold ionization (MATI) spectroscopy supported by DFT calculations. The precise ionization energy of Cp*₂Mn is determined as 5.349 ± 0.001 eV. The DFT modeling of the MATI spectrum shows that the main structural deformations accompanying the detachment of an electron consist in the elongation of the Mn-C bonds and a change in the Me out-of-plane bending angles. Surprisingly, the DFT calculations predict that most of the reduction in electron density (ED) upon ionization is associated with the hydrogen atoms of the substituents, despite the metal character of the ionized orbital. However, the ED difference isosurfaces reveal a complex mechanism of the charge redistribution involving also the carbon atoms of the molecule.

Helical versus Flat Bis-Ferrocenyl End-Capped Peptides: The Influence of the Molecular Skeleton on Redox Properties

Despite the fact that peptide conjugates with a pendant ferrocenyl (Fc) have been widely investigated, bis-ferrocenyl end-capped peptides are rarely synthetized. In this paper, in addition to the full characterization of the Fc-CO-[L-Dap(Boc)]n-NH-Fc series, we report a comparison of the three series of bis-ferrocenyl homopeptides synthesized to date, to gain insights into the influence of α-amino isobutyric (Aib), 2,3-diamino propionic (Dap) and Cα,β-didehydroalanine (ΔAla) amino acids on the peptide secondary structure and on the ferrocene redox properties. The results obtained by 2D NMR analysis and X-ray crystal structures, and further supported by electrochemical data, evidence different behaviors depending on the nature of the amino acid; that is, the formation of 310-helices or fully extended (2.05-helix) structures. In these foldamers, the orientation of the carbonyl groups in the peptide helix yields a macrodipole with the positive pole on the N-terminal amino acid and the negative pole on the C-terminal amino acid, so that oxidation of the Fc moieties takes place more or less easily depending on the orientation of the macrodipole moment as the peptide chain grows. Conversely, the fully extended conformation adopted by ΔAla flat peptides neither generates a macrodipole nor affects Fc oxidation. The utilization as electrochemical and optical (Circular Dichroism) probes of the two terminal Fc groups, bound to the same peptide chain, makes it possible to study the end-to-end effects of the positive charges produced by single and double oxidations, and to evidence the presence "exciton-coupled" CD among the two intramolecularly interacting Fc groups of the L-Dap(Boc) series.

Covalent grafting diazotized black phosphorus with ferrocene oligomer towards smoke suppression and toxicity reduction

In comparison with the thermal hazard of polymers, noxious smoke and gas produced by the combustion of polymers make the environment self-purification a huge challenge. As a new type of a highly effective flame retardant, black phosphorus (BP) can effectively decrease the thermal hazard of polymers, but its performances in smoke suppression and toxicity reduction are unsatisfactory. In this article, a method of covalently grafting diazotized BP with a ferrocene oligomer was applied to promote the smoke suppression and toxicity reduction efficiency of BP. In our work, the BP-NH nanomaterials with a mass of amino groups on the surface were acquired by diazotizing the BP. Then, the BP-Fe was obtained by covalently grafting the ferrocene chloride salt and nitrogen-containing heterocycles on the surface of BP. The smoke production rate (SPR) and total smoke production (TSP) values of the epoxy resin (EP) decreased by 49.8% and 52.5% with the addition of 2 wt% BP-Fe, respectively. In comparison with previous studies, this work was far more effective than the previous work in smoke suppression and flame retardant. The release of toxic gases (CO and HCN) and volatile organic compounds in the EP was also effectively inhibited at the same time. In addition, the storage modulus and tensile strength of nanocomposites increased by 35.1% and 27.2% with the addition of 1 wt% BP-Fe. This work also provides a new idea on how to simultaneously strengthen the toxic smoke suppression, mechanical properties, and flame retardant of polymer materials.

Ultrasound-promoted preparation of polyvinyl ferrocene-based electrodes for selective formate separation: Experimental design and optimization

The selective separation of ions is a major technological challenge having far-ranging impacts from product separation in electrochemical production of base chemicals from CO₂ to water purification. In recent years, ion-selective electrochemical systems leveraging redox-materials emerged as an attractive platform based on their reversibility and remarkable ion selectivity. In the present study, we present an ultrasound-intensified fabrication process for polyvinyl ferrocene (PVF)-functionalized electrodes in a carbon nanotube (CNT) matrix for selective electro-adsorption of formate ions. To this end, a response surface methodology involving the Box-Behnken design with three effective independent variables, namely, PVF to CNT ratio, sonication duration, and ultrasonic amplitude was applied to reach the maximum formate adsorption efficiency. The fabricated electrodes were characterized using cyclic voltammetry, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). SEM images revealed that an optimized ultrasonic amplitude and sonication time provided remarkable improvements in electrode morphology. Through a sedimentation study, we qualitatively demonstrate that the main optimized conditions improved PVF/CNT dispersion stability, consequently providing the highest number of active surface sites for adsorption and the highest adsorption efficiency. The highest percentage of active electrode surface sites and the maximum adsorption efficiency were 97.8 and 90.7% respectively at a PVF/CNT ratio of 3, ultrasonication time of one hour, and 50% ultrasonic amplitude.

Picomolar glutathione detection based on the dual-signal self-calibration electrochemical sensor of ferrocene-functionalized copper metal-organic framework via solid-state electrochemistry of cuprous chloride

Chemical biosensing techniques are essential for food analysis and disease diagnosis. Nanomaterials with redox activity show great potential in electrochemical analysis, acting as signal labels or signal amplification unit, which can reflect the targets concentration in foods and biological samples. Here, an ultra-sensitive dual-signal intrinsic self-calibration electrochemical platform for GSH was firstly fabricated based on the novel electroactive nanomaterial of ferrocene-functionalized copper metal-organic framework (Fc-Cu-MOF). Due to the solid-state electrochemical property of cuprous chloride (CuCl), a sharp characteristic peak with an increased signal appears with the coexistence of chloride ions in solution. The stronger specific affinity between Cu⁺ and GSH than that of Cu⁺ and Cl^- triggers a "crowding effect" that causes the current signal of CuCl decrease greatly. Meanwhile, the peak current of ferrocene keeps unchanged as an internal reference. Based on the ratio of the peak current variation (ΔI_Cu/ΔI_Fc) as the signal output, Fc-Cu-MOF modified electrode showed wider linear range in 0.1 nM -1 μM for GSH with the detection limit as low as 0.025 nM. And the sensor was successfully applied in the determination of GSH with excellent recoveries in various real samples such as food and serum samples, providing good prospect in application of bioanalysis and food screening.

A ferrocene-containing nucleoside analogue targets DNA replication in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) is a disease that remains refractory to existing treatments including the nucleoside analogue gemcitabine. In the current study we demonstrate that an organometallic nucleoside analogue, the ferronucleoside 1-(S,Rp), is cytotoxic in a panel of PDAC cell lines including gemcitabine-resistant MIAPaCa2, with IC50 values comparable to cisplatin. Biochemical studies show that the mechanism of action is inhibition of DNA replication, S-phase cell cycle arrest and stalling of DNA-replication forks, which were directly observed at single molecule resolution by DNA-fibre fluorography. In agreement with this, transcriptional changes following treatment with 1-(S,Rp) include activation of three of the four genes (HUS1, RAD1, RAD17) of the 9-1-1 check point complex clamp and two of the three genes (MRE11, NBN) that form the MRN complex as well as activation of multiple downstream targets. Furthermore, there was evidence of phosphorylation of checkpoint kinases 1 and 2 as well as RPA1 and gamma H2AX, all of which are considered biochemical markers of replication stress. Studies in p53-deficient cell lines showed activation of CDKN1A (p21) and GADD45A by 1-(S,Rp) was at least partially independent of p53. In conclusion, because of its potency and activity in gemcitabine-resistant cells, 1-(S,Rp) is a promising candidate molecule for development of new treatments for PDAC.