One-Pot Hydrothermal Synthesis of Magnetite Prussian Blue Nano-Composites and Their Application to Fabricate Glucose Biosensor

New Insight into Assembled Fe3O4@PEI@Ag Structure as Acceptable Agent with Enzymatic and Photothermal Properties

Metal-based enzyme mimics are considered to be acceptable agents in terms of their biomedical and biological properties; among them, iron oxides (Fe₃O₄) are treated as basement in fabricating heterogeneous composites through variable valency integrations. In this work, we have established a facile approach for constructing Fe₃O₄@Ag composite through assembling Fe₃O₄ and Ag together via polyethyleneimine ethylenediamine (PEI) linkages. The obtained Fe₃O₄@PEI@Ag structure conveys several hundred nanometers (~150 nm). The absorption peak at 652 nm is utilized for confirming the peroxidase-like activity of Fe₃O₄@PEI@Ag structure by catalyzing 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂. The Michaelis–Menten parameters (K_m) of 1.192 mM and 0.302 mM show the higher catalytic activity and strong affinity toward H₂O₂ and TMB, respectively. The maximum velocity (V_max) value of 1.299 × 10⁻⁷ M∙s⁻¹ and 1.163 × 10⁻⁷ M∙s⁻¹ confirm the efficiency of Fe₃O₄@PEI@Ag structure. The biocompatibility illustrates almost 100% cell viability. Being treated as one simple colorimetric sensor, it shows relative selectivity and sensitivity toward the detection of glucose based on glucose oxidase. By using indocyanine green (ICG) molecule as an additional factor, a remarkable temperature elevation is observed in Fe₃O₄@PEI@Ag@ICG with increments of 21.6 °C, and the absorption peak is nearby 870 nm. This implies that the multifunctional Fe₃O₄@PEI@Ag structure could be an alternative substrate for formatting acceptable agents in biomedicine and biotechnology with enzymatic and photothermal properties.

A facile aqueous production of bisphosphonated-polyelectrolyte functionalized magnetite nanoparticles for pH-specific targeting of acidic-bone cells

Bone malignancy treatment is being hindered due to the insufficient selectivity of therapeutic nanoparticles towards malignant bone sites. Polyelectrolyte functionalized magnetic nanoparticles having dually specific pH-sensing ability and bisphosphonate moieties, can be an effective solution for selective targeting of bone malignancies. First, polyelectrolyte was prepared via N-carboxycitraconyzation of chitosan (NCCS) followed by successive functionalization with alendronic acid (AL) and fluorescein isothiocyanate (FITC). Then, Fe₃O₄-NCCS-FITC-AL nanoparticles were synthesized by a facile one-step microwave-assisted aqueous method via in situ surface functionalization. The formation, crystal structure, and surface conjugation of Fe₃O₄ nanoparticles with polyelectrolytic stabilizer were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analyses. Synthesized Fe₃O₄-NCCS-FITC-AL nanoparticles were superparamagnetic, colloidally stable and highly hemocompatible under physiological conditions. Moreover, at pH 5.0, Fe₃O₄-NCCS-FITC-AL nanoparticles formed a precipitate due to inversion of their surface charge. This pH-dependent charge-inversion drastically changed the interactions with erythrocytes and bones. Selective membranolysis of erythrocytes occurred at pH 5.0. The designed nanoparticles showed enough potential for selective targeting of pathological bone sites in early-stage magnetofluorescent imaging and as a therapeutics carrier to treat malignant bone diseases.

Synthesis of a bisphosphonated polyelectrolytic stabilizer to in situ fabricate and functionalize Fe₃O₄ nanoparticles and their pH-dependent hemolysis and bone-cell adhesion.

Designing electrochemical interfaces based on nanohybrids of avidin functionalized-carbon nanotubes and ruthenium nanoparticles as peroxidase-like nanozyme with supramolecular recognition properties for site-specific anchoring of biotinylated residues

We are reporting an original supramolecular architecture based on a rationally designed new nanohybrid with enhanced peroxidase-like activity and site-specific biorecognition properties using avidin-functionalized multi-walled carbon nanotubes (MWCNTs-Av) and Ru nanoparticles (RuNPs). The nanohybrid-electrochemical interface was obtained by drop-coating of MWCNTs-Av dispersion at glassy carbon electrodes (GCE) followed by solvent evaporation and further electrodeposition of RuNPs (50 ppm RuCl₂ for 15 s at -0.600 V). The simultaneous presence of MWCNTs and RuNPs produces a synergic effect on the non-enzymatic catatalytic reduction of H₂O₂ and allows the quantification of H₂O₂ in a wide linear range (from 5.0 × 10^-7 M to 1.75 × 10^-3 M) with a low limit of detection (65 nM). The avidin residues present in MWCNTs-Av/RuNPs hybrid nanomaterial allowed the anchoring by bioaffinity of biotinylated glucose oxidase (biot-GOx) as proof-of-concept of the analytical application of MWCNTs-Av platform for biosensors development. The resulting nanoarchitecture behaves as a bienzymatic-like glucose biosensor with a competitive analytical performance: linear range between 2.0 × 10^-5 M and 1.23 × 10^-3 M, sensitivity of (0.343 ± 0.002) μA mM^-1 or (2.60 ± 0.02) μA mM^-1 cm^-2, detection limit of 3.3 μM, and reproducibility of 5.2% obtained with five different GCE/MWCNTs-Av/RuNPs/biot-GOx bioplatforms prepared the same day using the same MWCNTs-Av dispersion, and 9.1% obtained with nine biosensors prepared in different days with nine different MWCNTs-Av dispersions. The average concentrations of glucose in Gatorade®, Red bull® and Pepsi® with the biosensor demonstrated excellent agreement with those reported in the commercial beverages.

The Investigation into the Toxic Potential of Iron Oxide Nanoparticles Utilizing Rat Pheochromocytoma and Human Neural Stem Cells

Magnetic iron oxide (Magnetite, Fe₃O₄) nanoparticles are widely utilized in magnetic resonance imaging (MRI) and drug delivery applications due to their superparamagnetism. Surface coatings are often employed to change the properties of the magnetite nanoparticles or to modulate their biological responses. In this study, magnetite nanoparticles were fabricated through hydrothermal synthesis. Hydrophobicity is often increased by surface modification with oleic acid. In this study, however, hydrophobicity was introduced through surface modification with n-octyltriethoxysilane. Both the uncoated (hydrophilic) and coated (hydrophobic) individual nanoparticle sizes measured below 20 nm in diameter, a size range in which magnetite nanoparticles exhibit superparamagnetism. Both types of nanoparticles formed aggregates which were characterized by SEM, TEM, and dynamic light scattering (DLS). The coating process significantly increased both individual particle diameter and aggregate sizes. We tested the neurotoxicity of newly synthesized nanoparticles with two mammalian cell lines, PC12 (rat pheochromocytoma) and ReNcell VM (human neural stem cells). Significant differences were observed in cytotoxicity profiles, which suggests that the cell type (rodent versus human) or the presence of serum matters for nanoparticle toxicology studies. Differences in nanoparticle associations/uptake between the two cell types were observed with Prussian Blue staining. Finally, safe concentrations which did not significantly affect neuronal differentiation profiles were identified for further development of the nanoparticles.

A rapid and efficient technique for liposomal and nonliposomal drug pharmacokinetics studies using magnetic nanoprobes and its application to leakage kinetics of liposomes

Currently, the pharmacokinetics of liposomes was researched in vivo by measuring the total amount of drug in plasma. This method of using the total drug amount instead of the free drug amount virtually increase the apparent exposure and apparent biological distribution. To solve this problem, we developed a rapid and efficient method by using well-established streptavidin-functional Fe₃O₄@PDA as the separation nanoprobes to efficiently isolate biotin-labeled DTX-liposomes over 75% from plasma in the presence of magnetic field. The isolation procedure takes only 20 min and the concentration of DTX in liposomes from plasma was determined by LC-MS/MS. The method for the determination of DTX in plasma was linear in the range of 5-5000 ng/mL, and the correlation coefficient was 0.9989. Results obtained in this study clearly demonstrated that the pharmacokinetic parameters of non-liposomal drug and total drug are different in vivo. Therefore, traditional method for studying the pharmacokinetics of liposomes in vivo is unreasonable, and the new method mentioned here provided a strategy for studying the pharmacokinetics of liposomes.

Calcium-carbonate packaging magnetic polydopamine nanoparticles loaded with indocyanine green for near-infrared induced photothermal/photodynamic therapy

Indocyanine green (ICG) is an efficient photosensitizer that can facilitate producing cytotoxic reactive oxygen species (ROS). At the same time, ICG also has characteristic absorption of near-infrared light and thus can induce a strong photothermal effect. Both of these important features of ICG may be applied for noninvasive light-induced tumor ablation. On the other hand, ICG is lack of stability in blood circulation and susceptible to aggregation or premature clearance from the body. These issues need to be effectively addressed before antitumor application of ICG becomes possible. Herein, a nanocomposite consisting of calcium carbonate modified magnetic polydopamine (PDA) nanoparticles and loaded with ICG, namely Fe₃O₄@PDA@CaCO₃/ICG (FPCI) NPs, was developed to integrate the photothermal capability of PDA with the photodynamic capability of ICG. Particularly, calcium carbonate not only entrapped ICG in the form of stable aggregate to evade blood clearance, but also facilitated controlled release of ICG in response to acidic tumor microenvironment via self-decomposition. With the aid of magnetic guidance, this multifunctional therapeutic agent makes it possible to achieve the combination of photothermal (PTT) and photodynamic therapies (PDT) against tumors, which was demonstrated by this proof-of-concept study based on in vitro and in vivo tumor models. STATEMENT OF SIGNIFICANCE: Currently, there is an ongoing trend of realizing precise and targeted tumor therapy using functional nanocomplexes. Magnetic particles, which can be manipulated by a magnetic field, have attracted increasing attention for tumor therapy. This submitted work demonstrated that calcium carbonate nanoshell was precipitated onto magnetic nanocores mediated by polydopamine. Moreover, indocyanine green (ICG), as a potent photosensitizer, was embedded in this nanocomplex and protected by the calcium carbonate nanoshell, resulting in high drug loading efficiency and enhanced drug stability on the carrier. This new nanocomposite was demonstrated to achieve controlled and pH-responsive release of ICG in tumor environment. This work explored the relationship between the physiochemical properties of the nanocomplex and their potential biomedical applications, aiming to inspire the development of analogous nanoplatforms featured with calcium carbonate blocks.

Ultra-Small Pd(0) Nanoparticles into a Designed Semisynthetic Lipase: An Efficient and Recyclable Heterogeneous Biohybrid Catalyst for the Heck Reaction under Mild Conditions

A novel heterogeneous enzyme-palladium (Pd) (0) nanoparticles (PdNPs) bionanohybrid has been synthesized by an efficient, green, and straightforward methodology. A designed Geobacillus thermocatenulatus lipase (GTL) variant genetically and then chemically modified by the introduction of a tailor-made cysteine-containing complementary peptide- was used as the stabilizing and reducing agent for the in situ formation of ultra-small PdNPs nanoparticles embedded on the protein structure. This bionanohybrid was an excellent catalyst in the synthesis of trans-ethyl cinnamate by Heck reaction at 65 °C. It showed the best catalytic performance in dimethylformamide (DMF) containing 10–25% of water as a solvent but was also able to catalyze the reaction in pure DMF or with a higher amount of water as co-solvent. The recyclability and stability were excellent, maintaining more than 90% of catalytic activity after five cycles of use.

Recent advances in designing nanomaterial based biointerfaces for electrochemical biosensing cardiovascular biomarkers

Early diagnosis of cardiovascular disease (CVD) is critically important for successful treatment and recovery of patients. At present, detection of CVD at early stages of its progression becomes a major issue for world health. The nanoscale electrochemical biosensors exhibit diverse outstanding properties, rendering them extremely suitable for the determination of CVD biomarkers at very low concentrations in biological fluids. The unique advantages offered by electrochemical biosensors in terms of sensitivity and stability imparted by nanostructuring the electrode surface together with high affinity and selectivity of bioreceptors have led to the development of new electrochemical biosensing strategies that have introduced as interesting alternatives to conventional methodologies for clinical diagnostics of CVD. This review provides an updated overview of selected examples during the period 2005-2018 involving electrochemical biosensing approaches and signal amplification strategies based on nanomaterials, which have been applied for determination of CVD biomarkers. The studied CVD biomarkers include AXL receptor tyrosine kinase, apolipoproteins, cholesterol, C-reactive protein (CRP), D-dimer, fibrinogen (Fib), glucose, insulin, interleukins, lipoproteins, myoglobin, N-terminal pro-B-type natriuretic peptide (BNP), tumor necrosis factor alpha (TNF-α) and troponins (Tns) on electrochemical transduction format. Identification of new specific CVD biomarkers, multiplex bioassay for the simultaneous determination of biomarkers, emergence of microfluidic biosensors, real-time analysis of biomarkers and point of care validation with high sensitivity and selectivity are the major challenges for future research.

Iron nanostructured catalysts: design and applications

This review is focused on the recent advances in the design of iron nanostructures and their catalytic applications.

Indocyanine Green-Conjugated Magnetic Prussian Blue Nanoparticles for Synchronous Photothermal/Photodynamic Tumor Therapy

Indocyanine green (ICG) is capable of inducing a photothermal effect and the production of cytotoxic reactive oxygen species for cancer therapy. However, the major challenge in applying ICG molecules for antitumor therapy is associated with their instability in aqueous conditions and rapid clearance from blood circulation, which causes insufficient bioavailability at the tumor site. Herein, we conjugated ICG molecules with Prussian blue nanoparticles enclosing a Fe₃O₄ nanocore, which was facilitated by cationic polyethyleneimine via electrostatic adsorption. The nanocarrier-loaded ICG formed stable aggregates that enhanced cellular uptake and prevented fluorescence quenching. Moreover, the strong superparamagnetism of the Fe₃O₄ core in the obtained nanocomposites further improved cellular internalization of the drugs guided by a localized magnetic field. The therapeutic efficacy of this nanoplatform was evaluated using tumor models established in nude mice, which demonstrated remarkable tumor ablation in vivo due to strong photothermal/photodynamic effects. This study provides promising evidence that this multifunctional nanoagent might function as an efficient mediator for combining photothermal and photodynamic cancer therapy.

Synthesis of nitrogen doped carbon quantum dots/magnetite nanocomposites for efficient removal of methyl blue dye pollutant from contaminated water

As a remedy for environmental pollution, a simple synthesis approach has been developed to prepare nitrogen doped carbon quantum dot/magnetite nanocomposites (Fe₃O₄@NCQDs NCs) using non-toxic and cost effective lemon juice as precursor for removal of organic dye pollutant. Fe₃O₄@NCQDs NCs were characterized by using UV-Vis spectroscopy, FTIR, XRD, FESEM, EDS, TEM, VSM and TGA/DTA. TEM results show spherical shaped Fe₃O₄@NCQDs NCs with an average particle size of 5 nm. Batch adsorption studies were done to investigate the tendency of the nanocomposites to remove representative methyl blue (MB) dye from aqueous solution. The effects of MB dye concentration, dosage of Fe₃O₄@NCQDs NC adsorbent, pH, contact time and temperature were optimized by varying one variable while all the other parameters were kept constant. The experiment showed rapid removal of MB dye within 20 minutes with an adsorption efficiency of over 90.84% under optimum conditions. The adsorption process fits the Freundlich isotherm model well with R² and n values of 0.993 and 1.842, respectively, at 298 K indicating the feasibility of the adsorption process. The adsorption process is spontaneous and involves exothermic behaviour as confirmed by thermodynamic studies. From a kinetic study, it was found that the pseudo-second order model is more suitable to describe the adsorption process than the pseudo-first order model for adsorption of MB dye onto Fe₃O₄@NCQDs NCs.

Herein, we report the green synthesis of magnetic, nitrogen doped carbon quantum dot/Fe₃O₄ NPs using aqueous lemon extract for the efficient removal of organic dye pollutants from contaminated water.

Facile Synthesis of a MoS2-Prussian Blue Nanocube Nanohybrid-Based Electrochemical Sensing Platform for Hydrogen Peroxide and Carcinoembryonic Antigen Detection

Herein, an electrochemical detection platform was designed based on a Prussian blue nanocube-decorated molybdenum disulfide (MoS₂-PBNCs) nanocomposite. Shape-controlled and high-dispersion PBNCs were supported on the MoS₂ nanosheet surface, which would be simply controlled by varying the experimental conditions. Expectedly, such obtained MoS₂-based nanocomposites possessed excellent electrocatalytic ability, which could be employed to construct an electrochemical sensor for nonenzymatic hydrogen peroxide (H₂O₂) detection. More interestingly, MoS₂-PBNCs nanocomposites could be utilized to construct a sensor for label-free detection of carcinoembryonic antigen (CEA). The electrochemical response of the MoS₂-based immunosensor was linear with the CEA concentration ranging from 0.005 to 10 ng mL^-1. Moreover, the detection limit was calculated to be 0.54 pg mL^-1. The acceptable selectivity and high stability made such immunosensors detect CEA in human serum with satisfactory results. All data indicated that this MoS₂-PBNCs nanocomposite may be a promising electrochemical sensing platform for the detection of chemical and biological molecules.

Functional magnetic Prussian blue nanoparticles for enhanced gene transfection and photothermal ablation of tumor cells

Functional magnetic Prussian blue nanoparticles as a gene carrier and photothermal agent for multi-modal cancer treatment under magnetic targeting.