Recent development of pH-responsive theranostic nanoplatforms for magnetic resonance imaging-guided cancer therapy

The acidic characteristic of the tumor site is one of the most well-known features and provides a series of opportunities for cancer-specific theranostic strategies. In this regard, pH-responsive theranostic nanoplatforms that integrate diagnostic and therapeutic capabilities are highly developed. The fluidity of the tumor microenvironment (TME), with its temporal and spatial heterogeneities, makes noninvasive molecular magnetic resonance imaging (MRI) technology very desirable for imaging TME constituents and developing MRI-guided theranostic nanoplatforms for tumor-specific treatments. Therefore, various MRI-based theranostic strategies which employ assorted therapeutic modes have been drawn up for more efficient cancer therapy through the raised local concentration of therapeutic agents in pathological tissues. In this review, we summarize the pH-responsive mechanisms of organic components (including polymers, biological molecules, and organosilicas) as well as inorganic components (including metal coordination compounds, metal oxides, and metal salts) of theranostic nanoplatforms. Furthermore, we review the designs and applications of pH-responsive theranostic nanoplatforms for the diagnosis and treatment of cancer. In addition, the challenges and prospects in developing theranostic nanoplatforms with pH-responsiveness for cancer diagnosis and therapy are discussed.

Synthesis and adsorption properties of gelatin-conjugated hematite (α-Fe2O3) nanoparticles for lead removal from wastewater

Gelatin-conjugated hematite nanoparticles (HT NPs) are prepared through the solid-state phase transformation in the presence of phosphate. Their adsorption capacity and kinetics are investigated for Pb removal in wastewater. The gelatin-conjugated HT NPs with a size of 4-6 nm exhibit an excellent Pb removal performance, with a high adsorption capacity of 169.49 mg g^-1 and a fast equilibrium adsorption kinetics, attributed to the large number of active sites and highly negative charge on the surface of HT NPs. Moreover, the magnetic property of HT NPs enables to selectively collect NPs in the wastewater by using a permanent magnet, leading to its high reusability.

Platinum-based chemotherapy via nanocarriers and co-delivery of multiple drugs

Platinum-based anticancer drugs can inhibit the growth of cancer cells by disrupting DNA replication, which makes them widely applicable in clinics for treating tumors and cancers. However, owing to the intrinsic or acquired drug resistance and severe side effects caused in the treatment, their successful clinical applications have been limited. Various strategies have been used to address these challenges. Nanocarriers have been used for platinum drug delivery because they can be effectively deposited in tumor tissues to reduce the damage to normal organs for an enhanced permeability and retention (EPR) effect. Furthermore, for synergizing the function of platinum-based drugs with different mechanisms to decrease the toxicities, multicomponent chemotherapy has become an imperative strategy in clinical cancer treatments. This review aims to introduce the mechanisms of action and limitations of platinum-based drugs in clinics, followed by providing the current advancement of nanocarriers including lipids, polymers, dendrimers, micelles and albumin for platinum drug delivery in cancer treatments. In addition, multicomponent chemotherapy based on platinum drugs is introduced in detail. Finally, the prospects of multicomponent chemotherapy for cancer treatment are discussed as well.

Methodology for characterization of platinum-based drug's targeted delivery nanosystems

Conventional anticancer therapies exploiting platinum-based drugs rely principally on the intravascular injection of the therapeutic agent. The anticancer drug is distributed throughout the body by the systemic blood circulation undergoing cellular uptake, rapid clearance and excretion. Consequently, only a small portion of the platinum-based drug reaches the tumor site, which is associated with severe side effects. For this reason, targeted delivery systems are of great need since they offer enhanced and selective delivery of a drug to cancerous cells making the therapy safe and more effective. Up to date, a variety of the Pt-based drug targeted delivery systems (Pt-based DTDSs) utilizing nanomaterials have been developed and tested using a range of analytical techniques that provided essential information on their synthesis, stability, biodistribution and cytotoxicity. Here we summarize those experimental techniques indicating their applicability at different stages of the research, as well as pointing out their strengths, advantages, drawbacks and limitations. Also, the existing strategies and approaches are critically reviewed with the objective to reveal and give rise to the development of the analytical methodology suitable for reliable Pt-based DTDSs characterization which would eventually result in novel therapies and better patients' outcomes.

Polyphenol-cisplatin complexation forming core-shell nanoparticles with improved tumor accumulation and dual-responsive drug release for enhanced cancer chemotherapy

Cisplatin (CDDP) is a potent first-line antitumor drug but suffers severe side effects and poor pharmacokinetics. Its complexation with polycarboxylic acids, such as polyglutamic acids, is generally used to fabricate nanoformulations for CDDP delivery; however, the multiple strong complexations makes intracellular drug release slow. Herein, we report a novel polyphenol-metal coordination method to fabricate CDDP-incorporated core-shell nanoparticles, which are stable in blood circulation but dissociate in the tumor. Methoxyl-PEG terminated with one or two gallic acids (PEG-GA or PEG-GA2) complexed CDDP and produced well-defined nanoparticles (PEG-GAx/Pt) with CDDP loading contents as high as 17.7% to 29.8%. The PEG-GAx/Pt nanoparticles were very stable in the physiological conditions and had slow blood clearance and efficient tumor accumulation, but dissociated quickly and released CDDP in response to the tumor acidity or elevated levels of reactive oxygen species (ROS). PEG-GAx/Pt nanoparticles exhibited improved antitumor efficiency against 4 T1 breast cancer and A549 lung carcinoma with much-reduced toxicity compared to free CDDP. The work demonstrates a new strategy of cisplatin-polyphenol coordination for developing platinum drugs' nanomedicines.

Microalgae-Templated Spray Drying for Hierarchical and Porous Fe3O4/C Composite Microspheres as Li-ion Battery Anode Materials

A method of microalgae-templated spray drying to develop hierarchical porous Fe₃O₄/C composite microspheres as anode materials for Li-ion batteries was developed. During the spray-drying process, individual microalgae serve as building blocks of raspberry-like hollow microspheres via self-assembly. In the present study, microalgae-derived carbon matrices, naturally doped heteroatoms, and hierarchical porous structural features synergistically contributed to the high electrochemical performance of the Fe₃O₄/C composite microspheres, enabling a discharge capacity of 1375 mA·h·g^-1 after 700 cycles at a current density of 1 A/g. Notably, the microalgal frameworks of the Fe₃O₄/C composite microspheres were maintained over the course of charge/discharge cycling, thus demonstrating the structural stability of the composite microspheres against pulverization. In contrast, the sample fabricated without microalgal templating showed significant capacity drops (up to ~40% of initial capacity) during the early cycles. Clearly, templating of microalgae endows anode materials with superior cycling stability.

Fabrication of γ-Fe2O3 Nanowires from Abundant and Low-cost Fe Plate for Highly Effective Electrocatalytic Water Splitting

Water splitting is thermodynamically uphill reaction, hence it cannot occur easily, and also highly complicated and challenging reaction in chemistry. In electrocatalytic water splitting, the combination of oxygen and hydrogen evolution reactions produces highly clean and sustainable hydrogen energy and which attracts research communities. Also, fabrication of highly active and low cost materials for water splitting is a major challenge. Therefore, in the present study, γ-Fe₂O₃ nanowires were fabricated from highly available and cost-effective iron plate without any chemical modifications/doping onto the surface of the working electrode with high current density. The fabricated nanowires achieved the current density of 10 mA/cm² at 1.88 V vs. RHE with the scan rate of 50 mV/sec. Stability measurements of the fabricated Fe₂O₃ nanowires were monitored up to 3275 sec with the current density of 9.6 mA/cm² at a constant potential of 1.7 V vs. RHE and scan rate of 50 mV/sec.

Synthesis, crystal structure and in vitro anticancer studies of two bis(8-quinolinolato-N,O)-platinum(II) complexes

Two bis(8-quinolinolato-N,O)-platinum(II) complexes, C18H12N2O2Pt (1) and C20H16N2O2Pt (2), were synthesized and characterized by FT-IR, elementary analysis and X-ray single crystal diffraction. Complex 1 crystallizes in monoclinic, space group P21/c with a = 9.3413(7), b = 10.3893(9), c = 14.8495(12) Å, β = 100.574(7)°, V = 1416.7(2) Å3. Complex 2 crystallizes in monoclinic, space group P21/n with a = 9.5115(11), b = 15.5692(18), c = 16.720(2) Å, β = 94.544(2)°, V = 2468.3(5) Å3. Intermolecular C-H···O hydrogen bonding interactions, as well as Pt···Pt and π-π stacking interactions, help to stabilize the crystal structures. The preliminary in vitro anticancer activity of complexes 1 and 2 and the corresponding ligands (L1 and L2) were investigated using human cervical (Hela) and hepatocellular carcinoma (Hep-G2) cancer cell lines. The platinum(II) complexes can greatly inhibit the cell proliferation and show stronger cytotoxic activities against the tested cancer cell lines than both ligands.

Sustainable Catalytic Activity of Ag-Coated Chitosan-Capped γ-Fe2O3 Superparamagnetic Binary Nanohybrids (Ag-γ-Fe2O3@CS) for the Reduction of Environmentally Hazardous Dyes-A Kinetic Study of the Operating Mechanism Analyzing Methyl Orange Reduction

The formation of binary nanohybrids consisting of environmentally benign components, γ-Fe₂O₃, chitosan (CS), and Ag (Ag-γ-Fe₂O₃@CS) (CSIOAg), containing very low concentration of Ag NPs (≤1.2 μM), has been reported. In the as-synthesized nanohybrids, the presence of γ-Fe₂O₃ (8.5 ± 0.8 nm) and Ag (5.9 ± 0.5 nm) are revealed by optical, XRD, TEM, and XPS analyses, and their presence in cubic phase is determined by XRD and SAED measurements. The catalytic activity of CSIOAg has been analyzed by performing the reduction of certain toxic dyes. Under all kinetic conditions, the reaction is attended by an induction period, which is reduced upon increasing [Ag] and [Dye] in a specific concentration range, as well as temperature, suggesting restructuring of the surface prior to reduction. In case of methyl orange (MO), the reduction results in its cleavage to produce N,N-dimethyl-1,4-phenylenediamine and sodium sulfanilate in a significantly higher (>97%) yield in a bimolecular reaction between MO and BH₄ ^-. The duration of induction period is regularly decreased and the rate of reduction (k _app) increases linearly with increasing Ag in the wide concentration range (0.03-2.4 μM). The reduction takes place with a second-order rate constant of 2.7 × 10⁴ dm³ mol^-1 s^-1, which is >3.5-fold higher than that in the absence of chitosan (IOAg) under identical experimental conditions. The kinetics of reduction of MO is controlled by the nature and extent of its adsorption on the catalyst surface. The weaker binding between MO and Ag catalyst only allows its effective reduction. The XPS analysis of CSIOAg and IOAg containing the same amount of Ag (1.2 μM) showed its higher amount on the surface of CSIOAg (0.12%) as compared to that of IOAg (0.09%). Detailed kinetic analysis of MO reduction, performed under pseudo-kinetic conditions for both the nanohybrids revealed them to follow Langmuir-Hinshelwood kinetic model and exhibited the recyclability up to 10 cycles with fairly high reaction efficiency and TOF, suggesting it to be a sustainable green nanosystem.

Half-Sandwich Ru(II) and Os(II) Bathophenanthroline Complexes Containing a Releasable Dichloroacetato Ligand

We report on the preparation and thorough characterization of cytotoxic half-sandwich complexes [Ru(η⁶-pcym)(bphen)(dca)]PF₆ (Ru-dca) and [Os(η⁶-pcym)(bphen)(dca)]PF₆ (Os-dca) containing dichloroacetate(1-) (dca) as the releasable O-donor ligand bearing its own cytotoxicity; pcym = 1-methyl-4-(propan-2-yl)benzene (p-cymene), bphen = 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline). Complexes Ru-dca and Os-dca hydrolyzed in the water-containing media, which led to the dca ligand release (supported by ¹H NMR and electrospray ionization mass spectra). Mass spectrometry studies revealed that complexes Ru-dca and Os-dca do not interact covalently with the model proteins cytochrome c and lysozyme. Both complexes exhibited slightly higher in vitro cytotoxicity (IC50 = 3.5 μM for Ru-dca, and 2.6 μM for Os-dca) against the A2780 human ovarian carcinoma cells than cisplatin (IC50 = 5.9 μM), while their toxicity on the healthy human hepatocytes was found to be IC50 = 19.1 μM for Ru-dca and IC50 = 19.7 μM for Os-dca. Despite comparable cytotoxicity of complexes Ru-dca and Os-dca, both the complexes modified the cell cycle, mitochondrial membrane potential, and mitochondrial cytochrome c release by a different way, as revealed by flow cytometry experiments. The obtained results point out the different mechanisms of action between the complexes.

Dual-modal imaging and excellent anticancer efficiency of cisplatin and doxorubicin loaded NaGdF4:Yb3+/Er3+ nanoparticles

NaGdF₄:Yb³⁺/Er³⁺ nanoparticles were synthesized via a modified hydrothermal route. The dependence of structure and morphology on the dosage of sodium polyacrylate was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The as-prepared nanoparticles could be used for T₂ weighted magnetic resonance imaging due to the paramagnetism of Gd³⁺. cis-dichlorodiamineplatinum (CDDP) could be loaded onto NaGdF₄:Yb³⁺/Er³⁺ nanoparticles through binding carboxyl in the form of Pt–O bonds, and doxorubicin (DOX) could be loaded via hydrogen bonding. DOX could also be loaded onto the NaGdF₄–CDDP composite in the same manner, and the loading efficiency of both drugs remained unchanged. Three as-prepared drug delivery systems were used for tumor inhibition both in vitro and in vivo, and the results indicated that NaGdF₄–CDDP–DOX displayed the greatest inhibitory capacity.

The drug delivery system NaGdF₄–CDDP–DOX showed best tumor inhibition capacity both in vitro and in vivo.

A multi-functional PEGylated gold(iii) compound: potent anti-cancer properties and self-assembly into nanostructures for drug co-delivery

Gold(iii) porphyrin-PEG conjugates [Au(TPP-COO-PEG5000-OCH3)]Cl (1) and [Au(TPP-CONH-PEG5000-OCH3)]Cl (2) have been synthesized and characterized. Based on the amphiphilic character of the conjugates, they were found to undergo self-assembly into nanostructures with size 120-200 nm and this did not require the presence of other surfactants or components for nano-assembly, unlike most conventional drug nano-formulations. With a readily hydrolyzable ester linkage, chemotherapeutic [Au(TPP-COOH)]+ exhibited triggered release from the conjugate 1 in acidic buffer solution as well as in vitro and in vivo without the formation of toxic side products. The nanostructures of 1 showed higher cellular uptake into cancer cells compared to non-tumorigenic cells, owing to their energy-dependent uptake mechanism. This, together with a generally higher metabolic rate and more acidic nature of cancer cells which can lead to faster hydrolysis of the ester bond, afforded 1 with excellent selectivity in killing cancer cells compared with non-tumorigenic cells in vitro. This was corroborated by fluorescence microscopy imaging and flow cytometric analysis of co-culture model of colon cancer (HCT116) and normal colon (NCM460) cells. In vivo experiments showed that treatment of nude mice bearing HCT116 xenografts with 1 resulted in significant inhibition of tumor growth and, more importantly, minimal systemic toxicity as revealed by histopathological analysis of tissue sections and blood biochemisty. The latter is explained by a lower accumulation of 1 in organs of treated mice at its effective dosage, as compared to that of other gold(iii) porphyrin complexes. Co-assembly of 1 and doxorubicin resulted in encapsulation of doxorubicin by the nanostructures of 1. The nanocomposites demonstrated a strong synergism on killing cancer cells and could overcome efflux pump-mediated drug-resistance in a doxorubicin-resistant ovarian cancer cell line (A2780adr) which was found in cells incubated with doxorubicin alone. Also, the nanocomposites accumulated more slowly in non-tumorigenic cells, resulting in a lower toxicity toward non-tumorigenic cells. These results indicate the potential application of 1 not only as an anti-cancer agent but also as a nanoscale drug carrier for chemotherapy.

Upconversion nanoparticles loaded with eIF4E siRNA and platinum(iv) prodrug to sensitize platinum based chemotherapy for laryngeal cancer and bioimaging

Eukaryotic translation initiation factor (eIF) 4E is a valuable marker in cancer prognostics in many human cancers.

Half-sandwich iridium N-heterocyclic carbene anticancer complexes

Half-sandwich iridium N-heterocyclic carbene complexes display potent anticancer activities and are attractive for development as new anticancer agents.

Magneto-chemotherapy for cervical cancer treatment with camptothecin loaded Fe3O4 functionalized β-cyclodextrin nanovehicle

We portray a novel way to synthesis of iron oxide magnetic nanoparticle incorporated β-cyclodextrin (β-CD) nanocarrier stabilized by ethylenediamine tetra acetic acid (EDTA) obtaining remarkable biocompatibility and biodegradability.

Glutathione boosting the cytotoxicity of a magnetic platinum(iv) nano-prodrug in tumor cells

Superparamagnetic iron oxide nanoparticles (SPIONs) are potential vehicles for targeted drug delivery and viable contrast agents for magnetic resonance imaging (MRI). A Pt^IV prodrug (HSPt) derived from functionalization of cisplatin with hydroxyl and succinate is conjugated with a poly(ethylene glycol) (PEG)-modified SPION for cancer therapy and monitoring of therapeutic responses. The relaxivity of HSPt-PEG-SPIONs is larger than that of commercial contrast agent Feridex, and a tumor-selective negative contrast is observed in MRI in a magnetic field. HSPt-PEG-SPIONs can be dissociated and reduced into Pt^II species by glutathione (GSH). Instead of forming DNA-Pt crosslinks, the reduced product induces direct DNA single- or double-strand breaks, which is uncommon for Pt drugs. The cytotoxicity of HSPt-PEG-SPIONs is positively correlated with the GSH level of tumor cells, which is opposite to the scenario of current Pt drugs. HSPt-PEG-SPIONs are as cytotoxic as cisplatin against cancer cells but are almost nontoxic towards normal cells. Since the mechanism of action of the nanocomposite is different from the established paradigm for Pt drugs, it may become a special theranostic agent for cancer treatment.

A supramolecular nanovehicle toward systematic, targeted cancer and tumor therapy

A supramolecular nanovehicle (denoted as SNV) was fabricated by encapsulating zinc phthalocyanine (ZnPc) and doxorubicin (DOX) into a copolymer (PVP-b-PAA-g-FA), so as to achieve systematic and synergistic chemotherapy-photodynamic therapy (PDT), targeted tumor imaging and therapy. The sophisticated copolymer designed in this work can load the PDT photosensitizer (ZnPc) and chemotherapy drug (DOX) simultaneously, which exhibits an excellent performance in chemotherapy-PDT targeted cancer and tumor therapy for both in vitro studies performed with HepG2 cells and in vivo tests with mice. This work provides a new drug formulation with a chemotherapy-PDT synergistic effect by virtue of the supramolecular material design, which possesses the advantages of an ultra-low drug dosage and highly-efficient in vivo targeted tumor imaging/therapy.

Functionalization of Platinum Complexes for Biomedical Applications

Platinum-based anticancer drugs are the mainstay of chemotherapy regimens in clinic. Nevertheless, the efficacy of platinum drugs is badly affected by serious systemic toxicities and drug resistance, and the pharmacokinetics of most platinum drugs is largely unknown. In recent years, a keen interest in functionalizing platinum complexes with bioactive molecules, targeting groups, photosensitizers, fluorophores, or nanomaterials has been sparked among chemical and biomedical researchers. The motivation for functionalization comes from some of the following demands: to improve the tumor selectivity or minimize the systemic toxicity of the drugs, to enhance the cellular accumulation of the drugs, to overcome the tumor resistance to the drugs, to visualize the drug molecules in vitro or in vivo, to achieve a synergistic anticancer effect between different therapeutic modalities, or to add extra functionality to the drugs. In this Account, we present different strategies being used for functionalizing platinum complexes, including conjugation with bisphosphonates, peptides, receptor-specific ligands, polymers, nanoparticles, magnetic resonance imaging contrast agents, metal chelators, or photosensitizers. Among them, bisphosphonates, peptides, and receptor-specific ligands are used for actively targeted drug delivery, polymers and nanoparticles are for passively targeted drug delivery, magnetic resonance imaging contrast agents are for theranostic purposes, metal chelators are for the treatment or prevention of Alzheimer's disease (AD), and photosensitizers are for photodynamic therapy of cancers. The rationales behind these designs are explained and justified at the molecular or cellular level, associating with the requirements for diagnosis, therapy, and visualization of biological processes. To illustrate the wide range of opportunities and challenges that are emerging in this realm, representative examples of targeted drug delivery systems, anticancer conjugates, anticancer theranostic agents, and anti-AD compounds relevant to functionalized platinum complexes are provided. All the examples exhibit new potential of platinum complexes for future applications in biomedical areas. The emphases of this Account are placed on the functionalization for targeted drug delivery and theranostic agents. In the end, a general assessment of various strategies has been made according to their major shortcomings and defects. The original information in this Account comes entirely from literature appearing since 2010.

Chemoradiotherapeutic Magnetic Nanoparticles for Targeted Treatment of Nonsmall Cell Lung Cancer

Lung cancer is the leading cause of cancer-related death in the United States and approximately 85% of all lung cancers are classified as nonsmall cell (NSCLC). We here use an innovative approach that may ultimately allow for the clinician to target tumors and aggressively reduce tumor burden in patients with NSCLC. In this study, a platinum (Pt)-based chemotherapeutic (cisplatin, carboplatin, or oxaliplatin) and holmium-165 (Ho), which can be neutron-activated to produce the holmium-166 radionuclide, have been incorporated together in a garnet magnetic nanoparticle (HoIG-Pt) for selective delivery to tumors using an external magnet. The synthesized magnetic HoIG nanoparticles were characterized using PXRD, TEM, ICP-MS, and neutron-activation. Platinum(II) drugs were incorporated onto HoIG, and these were characterized using FTIR, EDX, ICP-MS, and zeta potential measurements, and in vitro and in vivo studies were performed using a HoIG-platinum system. Results indicate that neutron-activated (166)HoIG-cisplatin is more toxic toward NSCLC A549 cells than is blank (166)HoIG and free cisplatin, and that when an external magnetic field is applied in vivo, higher tumor to liver ratios of Ho are observed than when no magnet is applied, suggesting that magnetic targeting is achieved using this system. Furthermore, an efficacy study demonstrated the inhibition of tumor growth by chemoradiotherapeutic magnetic nanoparticles, compared to no treatment controls.

Efficient synthesis of a maghemite/gold hybrid nanoparticle system as a magnetic carrier for the transport of platinum-based metallotherapeutics

The preparation and thorough characterization of a hybrid magnetic carrier system for the possible transport of activated platinum-based anticancer drugs, as demonstrated for cisplatin (cis-[Pt(NH₃)₂Cl₂], CDDP), are described. The final functionalized mag/Au–LA–CDDP* system consists of maghemite/gold nanoparticles (mag/Au) coated by lipoic acid (HLA; LA stands for deprotonated form of lipoic acid) and functionalized by activated cisplatin in the form of cis-[Pt(NH₃)₂(H₂O)₂]²⁺ (CDDP*). The relevant techniques (XPS, EDS, ICP-MS) proved the incorporation of the platinum-containing species on the surface of the studied hybrid system. HRTEM, TEM and SEM images showed the nanoparticles as spherical with an average size of 12 nm, while their superparamagnetic feature was proven by ⁵⁷Fe Mössbauer spectroscopy. In the case of mag/Au, mag/Au–HLA and mag/Au–LA–CDDP*, weaker magnetic interactions among the Fe³⁺ centers of maghemite, as compared to maghemite nanoparticles (mag), were detected, which can be associated with the non-covalent coating of the maghemite surface by gold. The pH and time-dependent stability of the mag/Au–LA–CDDP* system in different media, represented by acetate (pH 5.0), phosphate (pH 7.0) and carbonate (pH 9.0) buffers and connected with the release of the platinum-containing species, showed the ability of CDDP* to be released from the functionalized nanosystem.

One-step synthesis of carboxyl-functionalized rare-earth fluoride nanoparticles for cell imaging and drug delivery

CDDP was loaded onto the surface of carboxyl polymer-coated NaYF₄:Yb³⁺/Tm³⁺ nanoparticles prepared by hydrothermal treatment in the form of Pt–O bonds, and delivered through cellular uptake of the NaYF₄–CDDP composite.

Design of a versatile nanocomposite for ‘seeing’ drug release and action behavior

To design a new method for ‘seeing’ drug release and action behavior, we combined a rare-earth complex with a magnetic-core-coated phenyl mesoporous silica nanoparticles matrix, taking advantage of the drug coordination for real-time monitoring.

Fenton-like processes and adsorption using iron oxide-pillared clay with magnetic properties for organic compound mitigation

In this work, a new step was added to the classic route of iron-pillared clay obtention, resulting in a material with both magnetic and oxidative properties. The saturation of the material surface intercalated with trinuclear acetate-hydroxo iron (III) nitrate in glacial acetic acid atmosphere before heat treatment promoted magnetic phase formation (FePMAG). The material was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS), and X-ray photoelectron spectroscopy (XPS). FePMAG showed an increase of 0.57 nm in basal spacing which contributed to the specific surface area increase from 39.1 to 139.2 m(2)/g. The iron phase identified by XRD and XPS was maghemite, with a little presence of hematite formed by the trinuclear acetate-hydroxo iron (III) nitrate decomposition during heat treatment. In the adsorption tests, FePMAG displayed a good capacity for organic dye methylene blue (MB) removal, reaching 41 % at 150 min. Under photo-Fenton conditions, the material showed an excellent MB oxidation capacity, completely removing the color of the solution within 90 min. Identification of the oxidation products with lower molecular (m/z = 160, 220, and 369) mass was performed by electrospray ionization mass spectroscopy (ESI-MS).

4-aminobenzoic acid-coated maghemite nanoparticles as potential anticancer drug magnetic carriers: a case study on highly cytotoxic Cisplatin-like complexes involving 7-azaindoles

This study describes a one-pot synthesis of superparamagnetic maghemite-based 4-aminobenzoic acid-coated spherical core-shell nanoparticles (PABA@FeNPs) as suitable nanocomposites potentially usable as magnetic carriers for drug delivery. The PABA@FeNPs system was subsequently functionalized by the activated species (1* and 2*) of highly in vitro cytotoxic cis-[PtCl2(3Claza)2] (1; 3Claza stands for 3-chloro-7-azaindole) or cis-[PtCl2(5Braza)2] (2; 5Braza stands for 5-bromo-7-azaindole), which were prepared by a silver(I) ion assisted dechlorination of the parent dichlorido complexes. The products 1*@PABA@FeNPs and 2*@PABA@FeNPs, as well as an intermediate PABA@FeNPs, were characterized by a combination of various techniques, such as Mössbauer, FTIR and EDS spectroscopy, thermal analysis, SEM and TEM. The results showed that the products consist of well-dispersed maghemite-based nanoparticles of 13 nm average size that represent an easily obtainable system for delivery of highly cytotoxic cisplatin-like complexes in oncological practice.

Impact of Serum Proteins on MRI Contrast Agents: Cellular Binding and T2 relaxation

Superparamagnetic iron oxide nanoparticles (SPIONs) used as MRI contrast agents or for theranostic applications encounter a complex mixture of extracellular proteins that adsorb on the SPION surface forming a protein corona. Our goal was to understand how cellular binding and T₂ relaxation times are affected by this protein corona. Our studies focused on carboxymethyl dextran-modified SPIONs, chosen for their similarity to Resovist SPIONs used to detect liver lesions. Using a combination of fluorescence microscopy and flow cytometry, we find that the cellular binding of SPIONs to both macrophages and epithelial cells is significantly inhibited by serum proteins. To determine if this decreased binding is due to the iron oxide core or the carboxymethyl dextran surface coating, we functionalized polystyrene nanoparticles with a similar carboxymethyl dextran coating. We find a comparable decrease in cellular binding for the carboxymethyl dextran-polystyrene nanoparticles indicating that the carbohydrate surface modification is the key factor in SPION-cell interactions. NMR measurements showed that T₂ relaxation times are not affected by corona formation. These results indicate that SPIONs have a decreased binding to cells under physiological conditions, possibly limiting their use in theranostic applications. We expect these results will be useful in the design of SPIONs for future diagnostic and therapeutic applications.