Reactive oxygen species responsive chitooligosaccharides based nanoplatform for sonodynamic therapy in mammary cancer.

Sonodynamic therapy (SDT) has been extensively studied as a new type of non-invasive treatment for mammary cancer. However, the poor water solubility and defective biocompatibility of sonosensitizers during SDT hinder the sonodynamic efficacy. Herein, a nanoplatform has been developed to achieve high efficient SDT against mammary cancer through the host-guest interaction of ß-cyclodextrin/5-(4-hydroxyphenyl)-10,15,20-triphenylporphyrin (ß-CD-TPP) and ferrocenecarboxylic acid/chitooligosaccharides (FC-COS). Moreover, the glucose oxidase (GOx) was loaded through electrostatic adsorption, which efficiently restricts the energy supply in tumor tissues, thus enhancing the therapeutic efficacy of SDT for tumors. Under optimal conditions, the entire system exhibited favorable water solubility, suitable particle size and viable biocompatibility. This facilitated the integration of the characteristics of starvation therapy and sonodynamic therapy, resulting in efficient inhibition of tumor growth with minimal side effects in vivo. This work may provide new insights into the application of natural oligosaccharides for construct multifunctional nanocarrier systems, which could optimize the design and development of sonodynamic therapy strategies and even combination therapy strategies.

Ratiometric electrochemical biosensor based on hybridization chain reaction signal amplification for sensitive microRNA-155 detection.

In this work, a sensitive ratiometric electrochemical biosensor for microRNA-155 (miRNA-155) detection is reported based on a hybridization chain reaction amplifying the electrochemical signal. The biosensor was fabricated using Au NPs as a modified material to assemble capture DNA labeled with ferrocene (Fc) molecules, and a DNA probe labeled with methylene blue (MB) was employed for the signal probe. In the presence of target miRNA-155, it can be dual hybridized with capture and signal probe, especially with signal probe to continuously produce long concatemers containing lots of MB molecules. The electrochemical signal of Fc was used for the internal signal, and the signal from MB was used as an indicator signal. As the concentration of miRNA-155 was altered, the internal reference signal of Fc remained constant, and only the indicator signal changed in a sensitive way. The change in the ratio (IMB/IFc) between the indicator signal of MB and internal reference signal of Fc can be used to monitor the concentration of miRNA-155. Under optimal conditions, the prepared ratiometric biosensor could detect miRNA-155 within a wide linear range from 100 fM to 100 nM with low detection limit of 33 fM (at S/N = 3). Moreover, the biosensor was evaluated with human serum samples, and satisfactory recoveries were obtained, indicating that the ratiometric biosensor can be applied to clinical sample analysis.

"Rigid-Flexible" Dual-Ferrocene Chimeric Nanonetwork for Simultaneous Tumor-Targeted Tracing and Photothermal/Photodynamic Therapy.

There is an urgent need to develop phototherapeutic agents with imaging capabilities to assess the treatment process and efficacy in real-time during cancer phototherapy for precision cancer therapy. The safe near-infrared (NIR) fluorescent dyes have garnered significant attention and are desirable for theranostics agents. However, until now, achieving excellent photostability and fluorescence (FL) imaging capability in aggregation-caused quenching (ACQ) dyes remains a big challenge. Here, for the only FDA-approved NIR dye, indocyanine green (ICG), we developed a dual-ferrocene (Fc) chimeric nanonetwork ICG@HFFC based on the rigid-flexible strategy through one-step self-assembly, which uses rigid Fc-modified hyaluronic acid (HA) copolymer (HA-Fc) and flexible octadecylamine (ODA) bonded Fc (Fc-C18) as the delivery system. HA-Fc reserved the ability of HA to target the CD44 receptor of the tumor cell surface, and the dual-Fc region provided a rigid space for securely binding ICG through metal-ligand interaction and π-π conjugation, ensuring excellent photostability. Additionally, the alkyl chain provided flexible confinement for the remaining ICG through hydrophobic forces, preserving its FL. Thereby, a balance is achieved between outstanding photostability and FL imaging capability. In vitro studies showed improved photobleaching resistance, enhanced FL stability, and increased singlet oxygen (1O2) production efficiency in ICG@HFFC. Further in vivo results display that ICG@HFFC had good tumor tracing ability and significant tumor inhibition which also exhibited good biocompatibility.. Therefore, ICG@HFFC provides an encouraging strategy to realize simultaneous enhanced tumor tracing and photothermal/photodynamic therapy (PTT/PDT) and offers a novel approach to address the limitations of ACQ dyes.

Ferrocenyl Azoles: Versatile N-Containing Heterocycles and their Anticancer Activities.

The medicinal chemistry of ferrocene has gained its momentum after the discovery of biological activities of ferrocifen and ferroquine. These ferrocenyl drugs have been designed by replacing the aromatic moiety of the organic drugs, tamoxifen and chloroquine respectively, with a ferrocenyl unit. The promising biological activities of these ferrocenyl drugs have paved a path to explore the medicinal applications of several ferrocenyl conjugates. In these conjugates, the ferrocenyl moiety has played a vital role in enhancing or imparting the anticancer activity to the molecule. The ferrocenyl conjugates induce the cytotoxicity by generating reactive oxygen species and thereby damaging the DNA. In medicinal chemistry, the five membered nitrogen heterocycles (azoles) play a significant role due to their rigid ring structure and hydrogen bonding ability with the biomolecules. Several potent drug candidates with azole groups have been in use as chemotherapeutics. Considering the importance of ferrocenyl moiety and azole groups, several ferrocenyl azole conjugates have been synthesized and screened for their biological activities. Hence, in the view of a wide scope in the development of potent drugs based on ferrocenyl azole conjugates, herein we present the details of synthesis and the anticancer activities of ferrocenyl compounds bearing azole groups such as imidazole, triazoles, thiazole and isoxazoles.

An electrochemical ratiometric immunosensor for the detection of NMP22 based on ZIF-8@MWCNTs@Chit@Fc@AuNPs and AuPt-MB.

Nuclear matrix protein 22 (NMP22) is one of the most important tumor markers of bladder cancer and is significantly elevated in the urine of bladder cancer patients. Therefore, in this work, a highly sensitive ratiometric electrochemical immunosensor was constructed to detect NMP22 based on ZIF-8@MWCNTs@Chit@Fc@AuNPs composites. ZIF-8 had a large surface area and good adsorption ability. Multi-Walled Carbon Nanotubes (MWCNTs) can optimize the electrical conductivity of ZIF-8, so that the electrode surface of ferrocene (Fc) obtains a stable and strong electrochemical signal. In addition, AuPt-MB provided another strong detection signal methylene blue (MB) while immobilizing the secondary antibody (Ab2) through Au-N and Pt-N bonds. A ratiometric electrochemical sensor was formed based on ZIF-8@MWCNTs@Chit@Fc@AuNPs and AuPt-MB, which showed a great linear connection between IMB/IFc and the logarithmic concentration of NMP22 with a detection limit of 3.33 fg mL-1 (S/N = 3) under optimized specifications in the concentration interval of 0.01 pg mL-1 to 1000 ng mL-1. In addition, the ratiometric immunosensor showed good selectivity and stability.

Co-crosslinking strategy for dual functionalization of small magnetic nanoparticles with redox probes and biological probes.

Surface functionalization strategy is becoming a crucial bridge from magnetic nanoparticles (MNPs) to their broad bio-application. To realize the multiple functions of MNPs such as magnetic manipulation, target capture, and signal amplification in their use of electrochemical biosensing, co-crosslinking strategy was proposed here to construct dual-functionalized MNPs by combining ultra-sensitive redox moieties and specific biological probes. In this work, MNPs with a TEM size of 10 nm were synthesized by co-precipitation for amination and PEGylation to maintain colloid stability once dispersed in high-ionic-strength buffer (such as phosphate-buffered saline). Then, MNPs@IgG were prepared via the bis(sulfosuccinimidyl) suberate (BS3) cross-linker to conjugate these IgG onto the MNP surface, with a binding efficiency of 73%. To construct dual-functionalized MNPs, these redox probes of ferrocene-NHS (Fc) were co-crosslinked onto the MNP surface, together with IgG, by using BS3. The developed MNPs@Redox@IgG were characterized by SDS‒PAGE to identify IgG binding and by square wave voltammetry (SWV) to validate the redox signal. Additionally, the anti-CD63 antibodies were selected for the development of MNPs@anti-CD63 for use in the bio-testing of exosome sample capture. Therefore, co-crosslinking strategy paved a way to develop dual-functionalized MNPs that can be an aid of their potential utilization in diagnostic assay or electrochemical methods.

Hybrid nanoflower-based electrochemical lateral flow immunoassay for Escherichia coli O157 detection.

An electrochemical biosensor has been developed for detection of Escherichia coli O157 by integrating lateral flow with screen-printed electrodes. The screen-printed electrodes were attached under the lateral flow detection line, and organic-inorganic nanoflowers prepared from E. coli O157-specific antibodies as an organic component were attached to the lateral flow detection line. In the presence of E. coli O157, an organic-inorganic nanoflower-E. coli O157-antimicrobial peptide-labelled ferrocene sandwich structure is formed on the lateral flow detection line. Differential pulse voltammetry is applied using a smartphone-based device to monitor ferrocene on the detection line. The resulting electrochemical biosensor could specifically detect E. coli O157 with a limit of detection of 25 colony-forming units mL-1. Through substitution of antibodies of organic components in organic-inorganic nanoflowers, biosensors have great potential for the detection of other pathogens in biomedical research and clinical diagnosis.

Construction of Metal-Organic Framework as a Novel Platform for Ratiometric Determination of Cyanide.

Metal-organic frameworks (MOFs) are frequently utilized as sensing materials. Unfortunately, the low conductivity of MOFs hinder their further application in electrochemical determination. To overcome this limitation, a novel modification strategy for MOFs was proposed, establishing an electrochemical determination method for cyanides in Baijiu. Co and Ni were synergistically used as the metal active centers, with meso-Tetra(4-carboxyphenyl)porphine (TCPP) and Ferrocenecarboxylic acid (Fc-COOH) serving as the main ligands, synthesizing Ni/Co-MOF-TCPP-Fc through a hydrothermal method. The prepared MOF exhibited improved conductivity and stable ratio signals, enabling rapid and sensitive determination of cyanides. The screen-printed carbon electrodes (SPCE) were suitable for in situ and real-time determination of cyanide by electrochemical sensors due to their portability, low cost, and ease of mass production. A logarithmic linear response in the range of 0.196~44 ng/mL was demonstrated by this method, and the limit of detection (LOD) was 0.052 ng/mL. Compared with other methods, the sensor was constructed by a one-step synthesis method, which greatly simplifies the analysis process, and the determination time required was only 4 min. During natural cyanide determinations, recommended readouts match well with GC-MS with less than 5.9% relative error. Moreover, this electrochemical sensor presented a promising method for assessing the safety of cyanides in Baijiu.

Multifunctional Organometallic Compounds Active against Infective Trypanosomes: Ru(II) Ferrocenyl Derivatives with Two Different Bioactive Ligands.

Human African trypanosomiasis (HAT, sleeping sickness) and American trypanosomiasis (Chagas disease) are endemic zoonotic diseases caused by genomically related trypanosomatid protozoan parasites (Trypanosoma brucei and Trypanosoma cruzi, respectively). Just a few old drugs are available for their treatment, with most of them sharing poor safety, efficacy, and pharmacokinetic profiles. Only fexinidazole has been recently incorporated into the arsenal for the treatment of HAT. In this work, new multifunctional Ru(II) ferrocenyl compounds were rationally designed as potential agents against these pathogens by including in a single molecule 1,1'-bis(diphenylphosphino)ferrocene (dppf) and two bioactive bidentate ligands: pyridine-2-thiolato-1-oxide ligand (mpo) and polypyridyl ligands (NN). Three [Ru(mpo)(dppf)(NN)](PF6) compounds and their derivatives with chloride as a counterion were synthesized and fully characterized in solid state and solution. They showed in vitro activity on bloodstream T. brucei (EC50 = 31-160 nM) and on T. cruzi trypomastigotes (EC50 = 190-410 nM). Compounds showed the lowest EC50 values on T. brucei when compared to the whole set of metal-based compounds previously developed by us. In addition, several of the Ru compounds showed good selectivity toward the parasites, particularly against the highly proliferative bloodstream form of T. brucei. Interaction with DNA and generation of reactive oxygen species (ROS) were ruled out as potential targets and modes of action of the Ru compounds. Biochemical assays and in silico analysis led to the insight that they are able to inhibit the NADH-dependent fumarate reductase from T. cruzi. One representative hit induced a mild oxidation of low molecular weight thiols in T. brucei. The compounds were stable for at least 72 h in two different media and more lipophilic than both bioactive ligands, mpo and NN. An initial assessment of the therapeutic efficacy of one of the most potent and selective candidates, [Ru(mpo)(dppf)(bipy)]Cl, was performed using a murine infection model of acute African trypanosomiasis. This hit compound lacks acute toxicity when applied to animals in the dose/regimen described, but was unable to control parasite proliferation in vivo, probably because of its rapid clearance or low biodistribution in the extracellular fluids. Future studies should investigate the pharmacokinetics of this compound in vivo and involve further research to gain deeper insight into the mechanism of action of the compounds.

Dual-Mode Arginine Assay Based on the Conformation Switch of a Ferrocene-Grafted Polypeptide.

Both controllable regulation of the conformational structure of a polypeptide and specific recognition of an amino acid are still arduous challenges. Here, a novel dual-mode (electrochemical and colorimetric) biosensor was built for arginine (Arg) recognition based on a conformation switch, utilizing controllable and synergistic self-assembly of a ferrocene-grafted hexadecapeptide (P16Fc) with gold nanoparticles (AuNPs). Benefiting from the flexibility and unique topological structure of P16Fc formed nanospheres, the assembly and disassembly can undergo a conformation transition induced by Arg through controlling the distance and number of Fc detached from the gold surface, producing on-off electrical signals. Also, they can induce aggregation and dispersion of AuNPs in solution, causing a color change. The mechanism of Arg recognition with polypeptide conformation regulation was well explored by combining microstructure characterizations with molecular mechanics calculations. The electrochemical and colorimetric assays for Arg were successfully established in sensitive and selective manner, not only obtaining a very low detection limit, but also effectively eliminating the interference from other amino acids and overcoming the limitation of AuNP aggregation. Notably, the conformational change-based assay with the peptide regulated by the target will make a powerful tool for the amino acid biosensing and health diagnosis.

A novel dual-signal output strategy for POCT of CEA based on a smartphone electrochemical aptasensing platform.

A smartphone-based electrochemical aptasensing platform was developed for the point-of-care testing (POCT) of carcinoembryonic antigen (CEA) based on the ferrocene (Fc) and PdPt@PCN-224 dual-signal labeled strategy. The prepared PdPt@PCN-224 nanocomposite showed a strong catalytic property for the reduction of H2O2. Phosphate group-labeled aptamer could capture PdPt@PCN-224 by Zr-O-P bonds to form PdPt@PCN-224-P-Apt. Therefore, a dual signal labeled probe was formed by the hybridization between Fc-DNA and PdPt@PCN-224-P-Apt. The presence of CEA forced PdPt@PCN-224-P-Apt to leave the electrode surface due to the specific affinity, leading to the decrease of the reduction current of H2O2. At the same time, the Fc-DNA strand changed to hairpin structure, which made Fc closer to the electrode and resulted in the increase of the oxidation current of Fc. Thus, CEA can be accurately determined through both signals: the decrease of H2O2 reduction current and the increase of Fc oxidation current, which could avoid the false positive signal. Under the optimal conditions, the prepared aptasensor exhibited a wide linear range from 1 pg·mL-1 to 100 ng·mL-1 and low detection limits of 0.98 pg·mL-1 and 0.27 pg·mL-1 with Fc and PdPt@PCN-224 as signal labels, respectively. The aptasensor developed in this study has successfully demonstrated its capability to detect CEA in real human serum samples. These findings suggest that the proposed sensing platform will hold great potential for clinical tumor diagnosis and monitoring.

Ferrocene-based metal-organic frameworks with dual synergistic active sites for selectively electrochemical removal of arsenic from contaminated water.

The effective removal of trace levels of the highly toxic arsenite (As(Ⅲ)) from groundwater is crucial to address the threat to drinking water supply. Herein, we developed an electrochemical separation system utilizing redox-active ferrocene-based metal-organic frameworks (termed Fe-DFc) for selective removal of As(III). This system leveraged 1,1'-ferrocenedicarboxylic acid as a ligand coordinated with iron, enabling the highly selective capture and conversion of As(III) from groundwater. The Fe-DFc electrode-based electrochemical system not only effectively removed As(III) even in the presence of a 1250-fold excess of competing electrolytes, but also converted about 96 % of the adsorbed As(III) into the less toxic As(V), surpassing the results of those documented in the current literature. X-ray absorption fine structure analysis and density functional theory calculations demonstrated that the high selectivity of Fe-O6 moiety and the exceptional redox activity of Fc synergistically contributed to the efficient removal of As(III). Moreover, the electrochemical separation system enabled the remediation of arsenic-contaminated groundwater at a low energy cost of 0.033 kWh m-3 during long-term operation, highlighting the application potential of the electrochemical technology for arsenic removal from contaminated water.

High-Frequency Quartz Crystal Microbalance and Dual-Signaling Electrochemical Ratiometric Assays of PTP1B Activity Based on COF@Au@Fc Hybrids.

The abnormal expression of protein tyrosine phosphatase 1B (PTP1B) is highly related to several serious human diseases. Therefore, an accurate PTP1B activity assay is beneficial to the diagnosis and treatment of these diseases. In this study, a dual-mode biosensing platform that enabled the sensitive and accurate assay of PTP1B activity was constructed based on the high-frequency (100 MHz) quartz crystal microbalance (QCM) and dual-signaling electrochemical (EC) ratiometric strategy. Covalent-organic framework@gold nanoparticles@ferrocene@single-strand DNA (COF@Au@Fc-S0) was introduced onto the QCM Au chip via the chelation between Zr4+ and phosphate groups (phosphate group of the phosphopeptide (P-peptide) on the QCM Au chip and the phosphate group of thiol-labeled single-stranded DNA (S0) on COF@Au@Fc-S0) and used as a signal reporter. When PTP1B was present, the dephosphorylation of the P-peptide led to the release of COF@Au@Fc-S0 from the QCM Au chip, resulting in an increase in the frequency of the QCM. Meanwhile, the released COF@Au@Fc-S0 hybridized with thiol/methylene blue (MB)-labeled hairpin DNA (S1-MB) on the Au NPs-modified indium-tin oxide (ITO) electrode. This caused MB to be far away from the electrode surface and Fc to be close to the electrode, leading to a decrease in the oxidation peak current of MB and an increase in the oxidation peak current of Fc. Thus, PTP1B-induced dephosphorylation of the P-peptide was monitored in real time by QCM, and PTP1B activity was detected sensitively and reliably using this innovative QCM-EC dual-mode sensing platform with an ultralow detection limit. This platform is anticipated to serve as a robust tool for the analysis of protein phosphatase activity and the discovery of drugs targeting protein phosphatase.

Recent Advances in the Field of Amino Acid-Conjugated Aminoferrocenes-A Personal Perspective.

The development of turn-based inhibitors of protein-protein interactions has attracted considerable attention in medicinal chemistry. Our group has synthesized a series of peptides derived from an amino-functionalized ferrocene to investigate their potential to mimic protein turn structures. Detailed DFT and spectroscopic studies (IR, NMR, CD) have shown that, for peptides, the backbone chirality and bulkiness of the amino acid side chains determine the hydrogen-bond pattern, allowing tuning of the size of the preferred hydrogen-bonded ring in turn-folded structures. However, their biological potential is more dependent on their lipophilicity. In addition, our pioneering work on the chiroptical properties of aminoferrocene-containing peptides enables the correlation of their geometry with the sign of the CD signal in the absorption region of the ferrocene chromophore. These studies have opened up the possibility of using aminoferrocene and its derivatives as chirooptical probes for the determination of various chirality elements, such as the central chirality of amino acids and the helicity of peptide sequences.

Development of Novel Immobilized Copper-Ligand Complex for Click Chemistry of Biomolecules.

Copper-catalyzed azide-alkyne cycloaddition click (CuAAC) reaction is widely used to synthesize drug candidates and other biomolecule classes. Homogeneous catalysts, which consist of copper coordinated to a ligand framework, have been optimized for high yield and specificity of the CuAAC reaction, but CuAAC reaction with these catalysts requires the addition of a reducing agent and basic conditions, which can complicate some of the desired syntheses. Additionally, removing copper from the synthesized CuAAC-containing biomolecule is necessary for biological applications but inconvenient and requires additional purification steps. We describe here the design and synthesis of a PNN-type pincer ligand complex with copper (I) that stabilizes the copper (I) and, therefore, can act as a CuAAC catalyst without a reducing agent and base under physiologically relevant conditions. This complex was immobilized on two types of resin, and one of the immobilized catalyst forms worked well under aqueous physiological conditions. Minimal copper leaching was observed from the immobilized catalyst, which allowed its use in multiple reaction cycles without the addition of any reducing agent or base and without recharging with copper ion. The mechanism of the catalytic cycle was rationalized by density functional theory (DFT). This catalyst's utility was demonstrated by synthesizing coumarin derivatives of small molecules such as ferrocene and sugar.

Paclitaxel Overload Supramolecular Oxidative Stress Nanoamplifier with a CDK12 Inhibitor for Enhanced Cancer Therapy.

Combination therapy has emerged as a promising approach for treating tumors, although there is room for improvement. This study introduced a novel strategy that combined the enhancement of apoptosis, ferroptosis, and DNA damage to improve therapeutic outcomes for prostate cancer. Specifically, we have developed a supramolecular oxidative stress nanoamplifier, which was comprised of ß-cyclodextrin, paclitaxel, and ferrocene-poly(ethylene glycol). Paclitaxel within the system disrupted microtubule dynamics, inducing G2/M phase arrest and apoptosis. Concurrently, ferrocene utilized hydrogen peroxide to generate toxic hydroxyl radicals in cells through the Fenton reaction, triggering a cascade of reactive oxygen species expansion, reduction of glutathione levels, lipid peroxidation, and ferroptosis. The increased number of hydroxyl radicals and the inhibitory effect of THZ531 on DNA repair mechanisms exacerbated DNA damage within tumor cells. As expected, the supramolecular nanoparticles demonstrated excellent drug delivery ability to tumor cells or tissues, exhibited favorable biological safety in vivo, and enhanced the killing effect on prostate cancer.

Visible and Red Light-Triggered Anticancer Profile of a Ferrocene-Re(I)-Tricarbonyl Conjugate: Experimental and Theoretical Studies.

We have red-shifted the light absorbance property of a Re(I)-tricarbonyl complex via distant conjugation of a ferrocene moiety and developed a novel complex ReFctp, [Re(Fctp)(CO)3Cl], where Fctp = 4'-ferrocenyl-2,2':6',2″-terpyridine. ReFctp showed green to red light absorption ability and blue emission, indicating its potential for photodynamic therapy (PDT) application. The conjugation of ferrocene introduced ferrocene-based transitions, which lie at a higher wavelength within the PDT therapeutic window. The time-dependent density functional theory and excited state calculations revealed an efficient intersystem crossing for ReFctp, which is helpful for PDT. ReFctp elicited both PDT type I and type II pathways for reactive oxygen species (ROS) generation and facilitated NADH (1,4-dihydro-nicotinamide adenine dinucleotide) oxidation upon exposure to visible light. Importantly, ReFctp showed effective penetration through the layers of clinically relevant 3D multicellular tumor spheroids and localized primarily in mitochondria (Pearson's correlation coefficient, PCC = 0.65) of A549 cancer cells. ReFctp produced more than 20 times higher phototoxicity (IC50 ∼1.5 µM) by inducing ROS generation and altering mitochondrial membrane potential in A549 cancer cells than the nonferrocene analogue Retp, [Re(CO)3(tp)Cl], where tp = 2,2':6',2″-terpyridine. ReFctp induced apoptotic mode of cell death with a notable photocytotoxicity index (PI, PI = IC50dark/IC50light) and selectivity index (SI, SI = normal cell's IC50dark/cancer cell's IC50light) in the range of 25-33.

A highly stable electrochemical sensor with antifouling and antibacterial capabilities for mercury ion detection in seawater.

The monitoring of heavy metal ions in ocean is crucial for environment protection and assessment of seawater quality. However, the detection of heavy metal ions in seawater with electrochemical sensors, especially for long-term monitoring, always faces challenges due to marine biofouling caused by the nonspecific adsorption of microbial and biomolecules. Herein, an electrochemical aptasensor, integrating both antifouling and antibacterial properties, was developed for the detection of Hg2+ in the ocean. In this electrochemical aptasensor, eco-friendly peptides with superior hydrophilicity served as anti-biofouling materials, preventing nonspecific adsorption on the sensing interface, while silver nanoparticles were employed to eliminate bacteria. Subsequently, a ferrocene-modified aptamer was employed for the specific recognition of Hg2+, leveraging the aptamer's ability to fold into a thymine-Hg2+-thymine (T-Hg2+-T) structure upon interaction, and bringing ferrocene nearer to the sensor surface, significantly amplifying the electrochemical response. The prepared electrochemical aptasensor significantly reduced the nonspecific adsorption in seawater while maintaining sensitive electrochemical response. Furthermore, the biosensor exhibited a linear response range of 0.01-100 nM with a detection limit of 2.30 pM, and realized the accurate monitoring of mercury ions in real marine environment. The research results offer new insights into the preparation of marine antifouling sensing devices, and it is expected that sensors with antifouling and antimicrobial capabilities will find broad applications in the monitoring of marine pollutants.

Electrochemical biosensor based on RNA aptamer and ferrocenecarboxylic acid signal probe for C-reactive protein detection.

Monitoring health-related biomarkers using fast and facile detection techniques provides key physicochemical information for disease diagnosis or reflects body health status. Among them, electrochemical detection of various bio-macromolecules, e.g., the C-reactive protein (CRP), is of great interest in offering potential diagnosis for acute inflammation caused by infections, heart diseases, etc. Herein, a novel electrochemical aptamer biosensor was constructed from Ti3C2Tx MXene and in-situ reduced Au NPs for thiolated-RNA aptamer immobilization and CRP protein detection using Fc(COOH) as the signal probe. The sensory performances for CRP detection were optimized based on working conditions, including the incubation times and the pH. The large surface area offered by Ti3C2Tx MXene and high electrical conductivity originating from Au NPs endowed the as-fabricated aptamer biosensor with a decent sensitivity for CRP in a wide linear range of 0.05-80.0 ng/mL, good selectivity over interfering substances, and a low detection limit of 0.026 ng/mL. Such aptamer biosensors also detected CRP in serum samples using the spike & recovery method with reasonable recovery rates. The results demonstrated the potential of the as-fabricated electrochemical aptamer biosensor for fast and facile CRP detection in practical applications.

Ferrocene-modified half-sandwich iridium(III) and ruthenium(II) propionylhydrazone complexes and anticancer application.

Ferrocene, ruthenium(II) and iridium(III) organometallic complexes, potential substitutes for platinum-based drugs, have shown good application prospects in the field of cancer therapy. Therefore, in this paper, six ferrocene-modified half-sandwich ruthenium(II) and iridium(III) propionylhydrazone complexes were prepared, and the anticancer potential was evaluated and compared with cisplatin. These complexes showed potential in-vitro anti-proliferative activity against A549 cancer cells, especially for Ir-based complexes, and showing favorable synergistic anticancer effect. Meanwhile, these complexes showed little cytotoxicity and effective anti-migration activity. Ir3, the most active complex (ferrocene-appended iridium(III) complex), could accumulate in the intracellular mitochondria, disturb the cell cycle (S-phase), induce the accumulation of reactive oxygen species, and eventually cause the apoptosis of A549 cells. Then, the design of these complexes provides a good structural basis for the multi-active non­platinum organometallic anticancer complexes.