Trap & kill: a neutrophil-extracellular-trap mimic nanoparticle for anti-bacterial therapy

Fenton chemistry-mediated antimicrobials have demonstrated great promise in antibacterial therapy. However, the short life span and diffusion distance of hydroxyl radicals dampen the therapeutic efficiency of these antimicrobials. Herein, inspired by the neutrophil extracellular trap (NET), in which bacteria are trapped and agglutinated via electronic interactions and killed by reactive oxygen species, we fabricated a NET-mimic nanoparticle to suppress bacterial infection in a "trap & kill" manner. Specifically, this NET-mimic nanoparticle was synthesized via polymerization of ferrocene monomers followed by quaternization with a mannose derivative. Similar to the NET, the NET-mimic nanoparticles trap bacteria through electronic and sugar-lectin interactions between their mannose moieties and the lectins of bacteria, forming bacterial agglutinations. Therefore, they confine the spread of the bacteria and restrict the bacterial cells to the destruction range of hydroxyl radicals. Meanwhile, the ferrocene component of the nanoparticle catalyzes the production of highly toxic hydroxyl radicals at the H2O2 rich infection foci and effectively eradicates the agglutinated bacteria. In a mouse model of an antimicrobial-resistant bacteria-infected wound, the NET-mimic nanoparticles displayed potent antibacterial activity and accelerated wound healing.

Study on the anti-cancer activity of α-phenethylamine ferrocenecarboxylic acid co-crystals

Ferrocene derivatives show a wide range of pharmacological activities in the medical field, especially in the anti-tumor field, and can be used as candidate drugs or lead compounds for the treatment of tumors and other diseases. And α-phenethylamine is an important intermediate for the preparation of fine chemical products. (R)-(+)-1-Phenethylamine ferrocenecarboxylic acid/(S)-(-)-1-phenethylamine ferrocenecarboxylic acid were prepared, named compounds 1 and 2, respectively. Single crystal X-ray diffraction showed that compounds 1 and 2 crystallized in the orthorhombic system space group P21 21 21 , and the crystal structures of compounds 1 and 2 exhibited mirror symmetry. The inhibitory effect of two compounds on SW480, MDA-MB-231, and H1299 cells was tested by MTT colorimetry. The IC50 values of the compounds against cancer cells were also calculated. The anti-cancer effect was more pronounced for compounds in the S-configuration. Compound 2 made the wild-type cancer cells undergo apoptosis, thus preventing cancer; it also had the function of helping the cell gene repair defects.

Multifunctional siRNA/ferrocene/cyclodextrin nanoparticles for enhanced chemodynamic cancer therapy

The therapeutic outcome of chemodynamic therapy (CDT) is greatly hindered by the presence of oxidative damage repair proteins (MTH1) inside cancer cells. These oxidative damage repair proteins detoxify the action of radicals generated by Fenton or Fenton-like reactions. Hence, it is extremely important to develop a simple strategy for the downregulation of MTH1 protein inside cancer cells along with the delivery of metal ions into cancer cells. A one-pot host-guest supramolecular approach for the codelivery of MTH1 siRNA and metal ions into a cancer cell is reported. Our approach involves the fabrication of an inclusion complex between cationic β-cyclodextrin and a ferrocene prodrug, which spontaneously undergoes amphiphilicity-driven self-assembly to form spherical nanoparticles (NPs) having a positively charged surface. The cationic surface of the NPs was then explored for the loading of MTH1 siRNA through electrostatic interactions. Using HeLa cells as a representative example, efficient uptake of the NPs, delivery of MTH1 siRNA and the enhanced CDT of the nanoformulation are demonstrated. This work highlights the potential of the supramolecular approach as a simple yet efficient method for the delivery of siRNA across the cell membrane for enhanced chemodynamic therapy.

Phototriggered Cytotoxicity of Ferrocene-Based Micelles - A Nonconventional Approach to Phototherapy

We report the design, synthesis, and in vitro evaluation of stimuli-responsive nanoscale micelles that can be activated by light to induce a cytotoxic effect. Micelles were assembled from amphiphilic units made of a photoactivatable ferrocenyl linker, connected on one side to a lipophilic chain, and on the other side to a hydrophilic pegylated chain. In vitro experiments indicated that pristine micelles ("off" state) were nontoxic to MCF-7 cancer cells, even at high concentrations, but became potent upon photoactivation ("on" state). The illumination process led to the dissociation of the micelles and the concomitant release of iron species, triggering cytotoxicity.

The anticancer application of half-sandwich iridium(III) ferrocene-thiosemicarbazide Schiff base complexes

Ferrocenyl derivatives and organometallic iridium(III) complexes have been prospective substitutes for platinum-based anticancer drugs. Eight half-sandwich iridium(III) ferrocene-thiosemicarbazide (Fc-TSC) Schiff base anticancer complexes were prepared in this study. These complexes displayed a dimeric structure and exhibited a particular fluorescence due to the "enol" orientation of the TSC pro-ligand. An energy-dependent pathway of the uptake mechanism was ascertained, which ended in the lysosome and led to lysosome damage and apoptosis. Flow cytometry confirmed that the complexes could block the cell cycle (G1 phase) and improve the levels of intracellular reactive oxygen species, indicating an anticancer mechanism of oxidation. Then, a lysosomal-mitochondrial anticancer pathway was verified through western blotting. In vivo toxicity assays confirmed that these complexes showed better anti-migration ability and less toxicity in comparison to cisplatin. Thus, these complexes provide a new strategy for the design of non-platinum organometallic anticancer drugs.

Oxidation-derived anticancer potential of sumanene-ferrocene conjugates

An effective synthetic protocol towards the oxidation of sumanene-ferrocene conjugates bearing one to four ferrocene moieties has been established. The oxidation protocol was based on the transformation of FeII from ferrocene to FeIII-containing ferrocenium cations by means of the treatment of the title organometallic buckybowls with a mild oxidant. Successful isolation of these ferrocenium-tethered sumanene derivatives 5-7 gave rise to the biological evaluation of the first, buckybowl-based anticancer agents, as elucidated by in vitro assays with human breast adenocarcinoma cells (MDA-MB-231) and embryotoxicity trials in zebrafish embryos supported with in silico toxicology studies. The designed ferrocenium-tethered sumanene derivatives featured attractive properties in terms of their use in cancer treatments in humans. The tetra-ferrocenium sumanene derivative 7 featured especially beneficial biological features, elucidated by low (<40% for 10 μM) viabilities of MDA-MB-231 cancer cells together with a 1.4-1.7-fold higher viability of normal cells (human mammary fibroblasts, HMF) for respective concentrations. Compound 7 featured significant cytotoxicity against cancer cells thanks to the presence of sumanene and ferrocenium moieties; the latter motif also provided the selectivity of anticancer action. The biological properties of 7 were also improved in comparison with those of native building blocks, which suggested the effects of the presence of the sumanene skeleton towards the anticancer action of this molecule. Ferrocenium-tethered sumanene derivatives exhibited potential towards the generation of reactive oxygen species (ROS), responsible for biological damage to the cancer cells, with the most efficient generation of the tetra-ferrocenium sumanene derivative 7. Derivative 7 also did not show any embryotoxicity in zebrafish embryos at the tested concentrations, which supports its potential as an effective and cancer-specific anticancer agent. In silico computational analysis also showed no chromosomal aberrations and no mutation with AMES tests for the compound 7 tested with and without microsomal rat liver fractions, which supports its further use as a potent drug candidate in detailed anticancer studies.

Configurationally regulated half-sandwich iridium(III)-ferrocene heteronuclear metal complexes: Potential anticancer agents

Half-sandwich iridium(III) (IrIII) complexes and ferrocenyl (Fc) derivatives are becoming the research hotspot in the field of anticancer because of their good bioactivity and unique anticancer mechanism different from platinum-based drugs. Then, a series of half-sandwich IrIII-Fc pyridine complexes have been prepared through the structural regulation in this study. The incorporation of half-sandwich IrIII complex with Fc unit successfully improves their anticancer activity, and the optimal performance (IrFc5) is almost 3-fold higher than that of cisplatin against A549 cells, meanwhile, which also shows better anti-proliferative activity against A549/DDP cells. Complexes can aggregate in the intracellular lysosome of A549 cells and induce lysosomal damage, disrupt the cell cycle, increase the level of intracellular reactive oxygen species, and eventually lead to cell apoptosis. Half-sandwich IrIII-Fc heteronuclear metal complexes possess a different anticancer mechanism from cisplatin, which can serve as a potential alternative to platinum-based drugs and show a good application prospect.

A new ferrocene derivative blocks K-Ras localization and function by oxidative modification at His95

Ras proteins are membrane-bound GTPases that regulate essential cellular processes at the plasma membrane (PM). Constitutively active mutations of K-Ras, one of the three Ras isoforms in mammalian cells, are frequently found in human cancers. Ferrocene derivatives, which elevate cellular reactive oxygen species (ROS), have shown to block the growth of non-small cell lung cancers harboring oncogenic mutant K-Ras. Here, we tested a novel ferrocene derivative on the growth of pancreatic ductal adenocarcinoma and non-small cell lung cancer. Our compound, which elevated cellular ROS levels, inhibited the growth of K-Ras-driven cancers, and abrogated the PM binding and signaling of K-Ras in an isoform-specific manner. These effects were reversed upon antioxidant supplementation, suggesting a ROS-mediated mechanism. We further identified that K-Ras His95 residue plays an important role in this process, and it is putatively oxidized by cellular ROS. Together, our study demonstrates that the redox system directly regulates K-Ras/PM binding and signaling via oxidative modification at the His95, and proposes a role of oncogenic mutant K-Ras in the recently described antioxidant-induced growth and metastasis of K-Ras-driven cancers.

Bioisosteric ferrocenyl 1,3-thiazolidine-4-carboxylic acid derivatives: In vitro antiproliferative and antimicrobial evaluations

To improve the antiproliferative effect of ALC67 (diastereomeric mixture of ethyl 2-phenyl-3-propioloyl-1,3-thiazolidine-4-carboxylate), its structure was modified via (i) bioisosteric substitution of the phenyl ring by the ferrocene unit and (ii) replacing the propiolamide side-chain in ACL67 with other acyl groups having differing electrophilicities. In this way, a small library of methyl N-acyl-2-ferrocenyl-1,3-thiazolidine-4-carboxylates (13 compounds in total) was created and characterized by spectral and crystallographic means. The last N-acylation step was highly diastereoselective toward the cis-diastereomer. In solution, most of the obtained compounds existed as a mixture of two rotamers and displayed a preference for the syn-orientation around the CN bond. A twisted 5T4 envelope conformation was adopted by the derivative containing the N-phenoxyacetyl group in the crystalline state. Two derivatives with chloroacetyl and bromoacetyl groups in the N-3 side chain were cytotoxic to fibroblasts and hepatocellular cancer cells in the low micromolar range (IC50(MRC5) = 9.0 and 11.8 μM, respectively, and IC50(HepG2) = 10.6 and 18.4 μM, respectively) causing an effect similar to the lead compound (IC50(HepG2) = 10.0 μM) and cisplatin (IC50(MRC5) = 4.0 μM and IC50(HepG2) = 7.7 μM). Several derivatives also manifested modest antimicrobial effects against the studied microbial strains (MICs in the range from 0.44 to 4.0 μmol/mL). Our findings demonstrated that the introduction of a ferrocene core facilitated the preparation of optically pure analogs of ALC67 and that the cytotoxicity of compounds may be enhanced by adding proper electrophilic centers to the N-acyl side-chain.

Effects of Ferrocene and Ferrocenium on MCF-7 Breast Cancer Cells and Interconnection with Regulated Cell Death Pathways

The effects of ferrocene (Fc) and ferrocenium (Fc+) induced in triple negative human breast cancer MCF-7 cells were explored by immunofluorescence, flow cytometry, and transmission electron microscopy analysis. The different abilities of Fc and Fc+ to produce reactive oxygen species and induce oxidative stress were clearly observed by activating apoptosis and morphological changes after treatment, but also after tests performed on the model organism D. discoideum, particularly in the case of Fc+. The induction of ferroptosis, an iron-dependent form of regulated cell death driven by an overload of lipid peroxides in cellular membranes, occurred after 2 h of treatment with Fc+ but not Fc. However, the more stable Fc showed its effects by activating necroptosis after a longer-lasting treatment. The differences observed in terms of cell death mechanisms and timing may be due to rapid interconversion between the two oxidative forms of internalized iron species (from Fe2+ to Fe3+ and vice versa). Potential limitations include the fact that iron metabolism and mitophagy have not been investigated. However, the ability of both Fc and Fc+ to trigger different and interregulated types of cell death makes them suitable to potentially overcome the shortcomings of traditional apoptosis-mediated anticancer therapies.

pH/GSH dual-responsive supramolecular nanomedicine for hypoxia-activated combination therapy

Moderate oxygen (O2) supply and uneven distribution of oxygen at the tumor site usually hinder the therapeutic efficacy of hypoxia-activated prodrugs. In this report, we designed a ferrocene-containing supramolecular nanomedicine (PFC/GOD-TPZ) with the PEG corona and disulfide-bond cross-linked core to co-encapsulate 4-di-N-oxide tirapazamine (TPZ) and glucose oxidase (GOD). The PEG corona of PFC/GOD-TPZ could be weakly acidic tumor pH-responsively detached for an enhanced cellular internalization, while the disulfide-bond cross-linked core could be cleavaged by intracellular glutathione (GSH) to present a GSH-triggered drug-release behavior. Subsequently, the cascade reactions, including catalytic reactions among the released GOD, glucose, and O2 to generate H2O2 and the subsequent Fenton reaction between ferrocene and H2O2, occurred. With the depletion of O2, the non-toxic TPZ was activated and converted into the cytotoxic therapeutic agent benzotriazinyl (BTZ) radical under the exacerbated hypoxic microenvironment. Collectively, the PFC/GOD-TPZ provides a promising strategy for effective combination therapy of GOD-mediated starvation therapy, chemodynamic therapy (CDT), and hypoxia-activated chemotherapy (CT).

Effects of Conjugation of Ferrocene and Gallic Acid On desCys11/Lys12/Lys13-(p-BthTX-I)2K Peptide: Structure, Permeabilization and Antibacterial Activity

BACKGROUND

Antimicrobial resistance is an emerging global health challenge that has led researchers to study alternatives to conventional antibiotics. A promising alternative is antimicrobial peptides (AMPs), produced as the first line of defense by almost all living organisms. To improve its biological activity, the conjugation of AMPs is a promising approach.

OBJECTIVE

In this study, we evaluated the N-terminal conjugation of p-Bt (a peptide derived from Bothrops Jararacuçu`s venom) with ferrocene (Fc) and gallic acid (GA). Acetylated and linear versions of p-Bt were also synthesized to evaluate the importance of N-terminal charge and dimeric structure.

METHODS

The compounds were obtained using solid-phase peptide synthesis. Circular dichroism, vesicle permeabilization, antimicrobial activity, and cytotoxicity studies were conducted.

RESULTS

No increase in antibacterial activity against Escherichia coli was observed by adding either Fc or GA to p-Bt. However, Fc-p-Bt and GA-p-Bt exhibited improved activity against Staphylococcus aureus. No cytotoxicity upon fibroblast was observed for GA-p-Bt. On the other hand, conjugation with Fc increased cytotoxicity. This toxicity may be related to the membrane permeabilization capacity of this bioconjugate, which showed the highest carboxyfluorescein leakage in vesicle permeabilization experiments.

CONCLUSION

Considering these observations, our findings highlight the importance of adding bioactive organic compounds in the N-terminal position as a tool to modulate the activity of AMPs.

Anticancer application of ferrocene appended configuration-regulated half-sandwich iridium(III) pyridine complexes

Ferrocenyl derivatives and half-sandwich iridium(III) complexes have received extensive attention in the field of anticancer. In this paper, series of configuration-controlled ferrocene-modified half-sandwich iridium(III) pyridine complexes were prepared. The combination of half-sandwich iridium(III) complexes and ferrocenyl unit successfully improved the anticancer activity of these complexes, especially for trans-configurational one towards A549 cells, and the best-performing (FeIr5) was almost 3.5 times more potent than that of cisplatin. In addition, these complexes could inhibit the migration of A549 cells. Complexes can accumulate in intracellular lysosomes (PCC: >0.75), induce lysosomal damage, disturb the cell circle, decrease the mitochondrial membrane potential, improve the intracellular reactive oxygen species (ROS) levels, and eventually lead to apoptosis. Meanwhile, complexes could bind to serum protein following a static quenching mechanism and transport through it. Then, ferrocene-modified half-sandwich iridium(III) pyridine complexes hold the promise as potential organometallic anticancer agents for further investigation.

Harmicens, Novel Harmine and Ferrocene Hybrids: Design, Synthesis and Biological Activity

Cancer and malaria are both global health threats. Due to the increase in the resistance to the known drugs, research on new active substances is a priority. Here, we present the design, synthesis, and evaluation of the biological activity of harmicens, hybrids composed of covalently bound harmine/β-carboline and ferrocene scaffolds. Structural diversity was achieved by varying the type and length of the linker between the β-carboline ring and ferrocene, as well as its position on the β-carboline ring. Triazole-type harmicens were prepared using Cu(I)-catalyzed azide-alkyne cycloaddition, while the synthesis of amide-type harmicens was carried out by applying a standard coupling reaction. The results of in vitro biological assays showed that the harmicens exerted moderate antiplasmodial activity against the erythrocytic stage of P. falciparum (IC50 in submicromolar and low micromolar range) and significant and selective antiproliferative activity against the MCF-7 and HCT116 cell lines (IC50 in the single-digit micromolar range, SI > 5.9). Cell localization experiments showed different localizations of nonselective harmicene 36 and HCT116-selective compound 28, which clearly entered the nucleus. A cell cycle analysis revealed that selective harmicene 28 had already induced G1 cell cycle arrest after 24 h, followed by G2/M arrest with a concomitant drastic reduction in the percentage of cells in the S phase, whereas the effect of nonselective compound 36 on the cell cycle was much less pronounced, which agreed with their different localizations within the cell.

Borax exerts protective effect against ferrocene-induced neurotoxicity in Oncorhynchus mykiss

BACKGROUND

In recent years, therapeutic targets and the development of new drugs have shifted research towards inflammatory and oxidative stress pathways. Ferrocene (FcH) is a stable, small molecule that exhibits immunostimulatory and anti-tumor properties by a different mechanism and is effective at low doses in oral administration. However, it was surprising that there has been no performed investigation using FcH on aquaculture. On the other hand, recent papers reveal the key biological functions and health benefits due to daily boron intake in animals and humans. Therefore, we investigated the neurotoxic damage potential of FcH and its related neurotoxicity action mechanism in aquatic environments. In addition, the protective potential of borax (BX, or sodium borate) were evaluated againt in vivo neurotoxicity by FcH.

METHODS

Neurotoxicity assessment was performed in rainbow trout brain tissue, acutely under semi-static conditions via determining a vide range of parameters including catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD) activities as well as glutathione (GSH), myeloperoxidase (MPO), glutathione (GSH), malondialdehyde (MDA levels), DNA damage (8-OHdG), apoptosis (caspase 3), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), nuclear factor erythroid-2 (Nrf-2), acetylcholinesterase (AChE) and brain-derived neurotrophic factor (BDNF) levels. In addition, the LC₅₀ 96 h level of FcH was determined for the first time in rainbow trout in this study.

RESULTS

In the obtained results, while FcH caused inhibition in enzyme activities, it showed an inducing effect on MDA, MPO, BDNF, Nrf2, TNF-α and IL-6 levels. It was determined that this oxidative damage related alterations were significantly different (p < 0.05) in comparison between FcH treated and controls. Again, the LC₅₀ 96 h value in rainbow trout was determined as 11.73 mg/L, which is approximately 5% less than the value given for freshwater fish (12.3 mg/L). On the contrary, it was observed that BX has a mitigating effect on FcH-induced neurotoxicity.

CONCLUSION

The present study suggests that borax may be useful for preventing or alleviating neurotoxicity induced by environmental contaminants or toxic chemicals.

Tumor microenvironment responsive polypeptide-based supramolecular nanoprodrugs for combination therapy

Tumor microenvironment responsive nanomedicine has drawn considerable attention for combination therapy, but still remains a significant challenge for less side effects and enhanced anti-tumor efficiency. Herein, we develop a pH/ROS dual-responsive supramolecular polypeptide nanoprodrug (PFW-DOX/GOD) by using pillar[5]arene-based host-guest strategy for combined glucose degradation, chemodynamic therapy (CDT), and chemotherapy (CT). The PFW-DOX/GOD consists of a pH-responsive ferrocene/pillar[5]arene-containing polypeptide, a ROS-responsive polyprodrug, and encapsulated glucose oxidase (GOD). Upon into intracellular acidic environment, PFW-DOX/GOD exhibits rapid pH-triggered disassembly behavior. Simultaneously, the released GOD can catalyze intratumoral glucose into massive H₂O₂, which are further converted into highly toxic hydroxyl radicals (•OH) by the catalysis of ferrocene via the Fenton reaction. Thereafter, induced by the ROS-responsive cleavage of thioketal linkage, the conjugated DOX prodrug was released and activated. The combined glucose degradation, chemodynamic therapy (CDT), and chemotherapy (CT) of PFW-DOX/GOD present anti-tumor effect with 96% of tumor inhibitory rate (TIR). Therefore, such tumor microenvironment-responsive supramolecular polypeptide nanoprodrugs represent a potential candidate for combination therapy with minimal side effects. STATEMENT OF SIGNIFICANCE: In this work, a tumor microenvironment-responsive supramolecular polypeptide nanoprodrug (PFW-DOX/GOD) was prepared via pillar[5]arene-based host-guest interactions, and presented low side effects and high tumor accumulation owing to the diameters of about 200 nm and surface PEG segment. After pH-responsive release of GOD in the intracellular acidic environment, the cascade catalytic reactions including GOD-catalyzed degradation of intratumoral glucose and Fenton reaction, effectively happened to generate •OH for chemodynamic therapy (CDT), which subsequently induced the cleavage of thioketal linkage to activate free DOX for chemotherapy (CT). Collectively, this supramolecular polypeptide nanoprodrugs provide a promising strategy for combination therapy with synergetic anti-tumor effect.

Naringenin enhances anti-proliferation effect of 1-ferrocenyl-3-(4-methylsulfonylphenyl) propen-1-one on two different cells via targeting calmodulin signaling pathway

BACKGROUND

FMSP is a synthesized ferrocene derivative with anti-cancer characteristics on tumor cells. Naringenin is a polyphenolic flavonoid with anti-tumor ability.

METHODS

Cell viability and proliferation of two cancer cells and a normal cell line after treatment with these agents were determined with MTT assay. To predict the possible interaction between calmodulin (CaM) and FMSP and naringenin, docking studies were performed. By using fluorescence emission spectra, the effects of FMSP and naringenin on CaM structure and activity were studied. CaM-dependent activation of phosphodiesterase 1 (PDE1) by FMSP in relation to naringenin and their combination were compared. Effects of these compounds on PDE1 inhibition, cAMP accumulation, and cAMP-dependent protein kinase A (PKA) activation were assayed.

RESULTS

The combination of FMSP and naringenin had more inhibitory effects on CaM structure than FMSP and naringenin alone. Results of docking analyses also confirmed efficient interaction of the two compounds with a hydrophobic pocket of calmodulin active site. Kinetic analyses of these agents' interaction with CaM showed FMSP and naringenin both competitively inhibited PDE1 activation without changing the Vmax parameter. FMSP and naringenin synergistically increased Km values at a higher level compared to FMSP or naringenin alone. The combination of these two agents also had more cytotoxic effects on cancer cells than FMSP alone.

CONCLUSIONS

It was shown that mechanism of proliferation inhibition in both cancer cells by these compounds is based on CaM and consequent PDE inhibition followed by intracellular cAMP level elevation and increased PKA activity in a dose-dependent manner.

Pillar[6]arene-Based Supramolecular Nanocatalysts for Synergistically Enhanced Chemodynamic Therapy by the Intracellular Cascade Reaction

Chemodynamic therapy (CDT) based on the intracellular Fenton reaction has become increasingly explored in cancer treatment. However, the mildly acidic tumor microenvironment and the limited amount of intracellular hydrogen peroxide (H₂O₂) will create issues for CDT to perform a sustained and high-efficiency treatment. Therefore, how to selectively reduce the pH value and augment the amount of H₂O₂ in tumor tissues has become the key factor for realizing excellent CDT. Besides, the majority of the reported CDT systems have been constructed from iron-based inorganic or metal-organic framework nanomaterials due to the decisive role of metals in CDT, which restricts the development of CDT. In this study, inspired by the host-guest interactions between pillar[6]arene and ferrocene, a ternary pillar[6]arene-based supramolecular nanocatalyst (GOx@T-NPs) for CDT is reported for the first time. GOx@T-NPs not only exhibited a high-efficiency catalytic ability to convert glucose into hydroxyl radicals (^•OH) and to reduce the pH value inside cancer cells for significant enhancement of the CDT effect, but they also showed sensitive glutathione-induced camptothecin (CPT) prodrug release capacity for further improving the efficiency of CDT. Hence, GOx@NPs possessed excellent ability to synergistically enhance the CDT. Additionally, an antitumor mechanism study showed that the prominent tumor inhibition capacity of GOx@T-NPs was derived from trimodal synergistic interactions of CDT, starvation therapy, and chemotherapy. Moreover, GOx@T-NPs manifested good biocompatibility and tumor selectivity with few side effects in major organs. This work broadens the range of materials available for CDT and demonstrates new developments in pillar[n]arene-based multimodal synergistic treatment systems.

Nanoparticles based on polymers modified with pH-sensitive molecular switch and low molecular weight heparin carrying Celastrol and ferrocene for breast cancer treatment

Triple negative breast cancer (TNBC) metastasis is still one of the obstacles in clinical treatment, while highly-effective cancer drugs usually cannot be used for their hydrophobicity and comprehensive system toxicity. This study built a kind of pH-sensitive nanoparticles (PP/H NPs) constructed by poly (lactic-co-glycolic acid) modified with β-cyclodextrin (PLGA-β-CD), polyethyleneimine grafted with benzimidazole (PEI-BM) and low molecular weight heparin (LMWH) to delivery Celastrol (Cela) and ferrocene (Fc) for breast cancer therapy. PLGA-β-CD and PEI-BM were synthesized by amidation reaction, the amphipathic polymer nanoparticles with 108.37 ± 1.02 nm were self-assembled in water. After PP/H NPs treatment, the half maximal inhibitory concentration (IC50) decreased by 91% compared with Cela, and ROS level was also elevated. PP/H NPs led to substantial tumor inhibiting rate (TIR, 65.86%), utilized LMWH to strengthen the anti-metastasis effect of PP/H NPs. PP/H NPs took advantage of exogenous chemotherapeutics and endogenous ROS to inhibit tumor growth, and combined with LMWH to hinder breast cancer metastasis.

Novel Ferrocene Derivatives Induce G0/G1 Cell Cycle Arrest and Apoptosis through the Mitochondrial Pathway in Human Hepatocellular Carcinoma

In this study, detailed information on hepatocellular carcinoma (HCC) cells (HepG-2, SMMC-7721, and HuH-7) and normal human liver cell L02 treated by ferrocene derivatives (compounds 1, 2 and 3) is provided. The cell viability assay showed that compound 1 presented the most potent and selective anti-HCC activity. Further mechanism study indicated that the proliferation inhibition effect of compound 1 was associated with the cycle arrest at the G0/G1 phase and downregulation of cyclin D1/CDK4. Moreover, compound 1 could induce apoptosis in HCC cells by loss of mitochondrial membrane potential (ΔΨm), accumulation of reactive oxygen species (ROS), decrease in Bcl-2, increase in BAX and Bad, translocation of Cytochrome c, activation of Caspase-9, -3, and cleavage of PARP. These results indicated that compound 1 would be a promising candidate against HCC through G0/G1 cell cycle arrest-related proliferation inhibition and mitochondrial pathway-dependent apoptosis.

Enhanced antitumor effect via amplified oxidative stress by near-infrared light-responsive and folate-targeted nanoplatform

The efficiency of producing hydroxyl radicals (·OH) from hydrogen peroxide (H₂O₂) catalyzed by different iron compounds have been explored extensively. Exclusively, ferrocenecarboxylic acid (FCA) showed the best catalyzed activity for ·OH generation. Then, we designed and prepared near-infrared (NIR) light-responsive and folate-targeted nanoplatform, which co-delivered FCA, cisplatin and indocyanine green (ICG) for improving antitumor therapy through amplified oxidative stress. The noteworthy observation is that under the irradiation of NIR light, the lecithin structure could able to depolymerize through the photothermal conversion mechanism of encapsulated dye ICG, which has achieved an intelligent release of drugs. In addition, the released cisplatin is not only fully effective to damage the DNA of cancer cells but it is able to induce the production of intracellular H₂O₂, which could further be catalyzed by FCA to generate toxic ·OH for oxidative damage via Fenton and Haber-Weiss reaction. This original strategy may provide an efficient way for improved chemotherapy via amplified oxidative stress.

New ferrocene-triazole derivatives for multisignaling detection of Cu2+ in aqueous medium and their antibacterial activity

Ferrocene-based naphthalene or quinoline receptors 1-4 linked by triazole were designed and synthesized. Their recognition properties of metal cations have been investigated systematically in aqueous environment. Upon addition 1 equiv. of Cu²⁺ ion, receptors 1 (C₂₃H₁₉FeN₃O) and 2 (C₂₂H₁₈FeN₄O) showed fluorescent turn-off, enhanced absorption and color variations. At the same time, receptor 1 also caused the perturbation of redox potential after addition 1 equiv. of Cu²⁺ ion. Therefore, receptors 1 and 2 behaved as naked-eye chemosensors and fluorescent probes for Cu²⁺ without interference by other ions and with low detection limit. In addition, receptor 1 could also be considered electrochemical sensor for Cu²⁺ having excellent sensitivity and selectivity. However, increasing the molecules flexibility resulted in the lower selectivity of ion recognition in the case of receptors 3 (C₂₄H₂₁FeN₃O) and 4 (C₂₃H₂₀FeN₄O). Furthermore, this series of compounds were nontoxicity and receptor 1 exhibited certain antibacterial activity.

Redox-Channeling Polydopamine-Ferrocene (PDA-Fc) Coating To Confer Context-Dependent and Photothermal Antimicrobial Activities

Microbial disinfection associated with medical device surfaces has been an increasing need, and surface modification strategies such as antibacterial coatings have gained great interest. Here, we report the development of polydopamine-ferrocene (PDA-Fc)-functionalized TiO₂ nanorods (Ti-Nd-PDA-Fc) as a context-dependent antibacterial system on implant to combat bacterial infection and hinder biofilm formation. In this work, two synergistic antimicrobial mechanisms of the PDA-Fc coating are proposed. First, the PDA-Fc coating is redox-active and can be locally activated to release antibacterial reactive oxygen species (ROS), especially ·OH in response to the acidic microenvironment induced by bacteria colonization and host immune responses. The results demonstrate that redox-based antimicrobial activity of Ti-Nd-PDA-Fc offers antibacterial efficacy of over 95 and 92% against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli), respectively. Second, the photothermal effect of PDA can enhance the antibacterial capability upon near-infrared (NIR) irradiation, with over 99% killing efficacy against MRSA and E. coli, and even suppress the formation of biofilm through both localized hyperthermia and enhanced ·OH generation. Additionally, Ti-Nd-PDA-Fc is biocompatible when tested with model pre-osteoblast MC-3T3 E1 cells and promotes cell adhesion and spreading presumably due to its nanotopographical features. The MRSA-infected wound model also indicates that Ti-Nd-PDA-Fc with NIR irradiation can effectively eliminate bacterial infection and suppress host inflammatory responses. We believe that this study demonstrates a simple means to create biocompatible redox-active coatings that confer context-dependent antibacterial activities to implant surfaces.

Ferrocene-Based Compounds with Antimalaria/Anticancer Activity

Malaria and cancer are chronic diseases. The challenge with drugs available for the treatment of these diseases is drug toxicity and resistance. Ferrocene is a potent organometallic which have been hybridized with other compounds resulting in compounds with enhanced biological activity such as antimalarial and anticancer. Drugs such as ferroquine were developed from ferrocene and chloroquine. It was tested in the 1990s as an antimalarial and is still an effective antimalarial. Many researchers have reported ferrocene compounds as potent compounds useful as anticancer and antimalarial agents when hybridized with other pharmaceutical scaffolds. This review will be focused on compounds with ferrocene moieties that exhibit either an anticancer or antimalarial activity.