Magnetic silica nanotubes: synthesis, drug release, and feasibility for magnetic hyperthermia

Synthesis of Hollow Silica Nanotubes from Linear Metallosupramolecular Polyelectrolytes and Their Application as Catalyst Supports for Hydrogenation

In this study, we report a facile templating method to construct hollow silica nanotubes. In particular, bis-terpyridine is used to coordinate metal ions to form polymeric bis-terpyridine-metal complexes that further self-assemble into tubular organogels in the presence of cetyltrimethylammonium bromide. The following silica deposition on organogels and subsequent calcination give metal oxide-doped hollow silica nanotubes (M_xO_y-HSNs). Facilitated by the high coordination stability constants of bis-terpyridine with metal ions, a series of metal ions, such as Fe, Ni, Cu, and Zn, could be used to form polymeric bis-terpyridine-metal complexes. The supported Pt/Fe_xO_y-HSNs exhibit good catalytic performance for hydrogenation of a series of substituted nitrobenzenes, showing that the obtained M_xO_y-HSNs could be used as catalyst supports due to their good textural properties.

Organic–inorganic hybrid nanomaterials prepared via polymerization-induced self-assembly: recent developments and future opportunities

This review highlights recent developments in the preparation of organic–inorganic hybrid nanomaterials via polymerization-induced self-assembly.

Organic and Inorganic Template-Assisted Synthesis of Silica Nanotubes and Evaluation of Their Properties

Mesoporous silica network nanotubes were fabricated using both organic and inorganic templates such as citric acid (CA), cetyltrimethylammonium bromide (CTAB), and sodium bicarbonate (SBC). The phase analysis of synthesized silica network was confirmed by X-ray diffractometer (XRD) analysis, and the present functional groups were revealed by Fourier Transform Infrared Spectroscopy (FTIR) and the formation of tubular morphology was analyzed by transmission electron microscopy (TEM). The mesoporous nature of each template sample was studied using Brunauer-Emmett-Teller (BET) instrument. The surface area and porous size were calculated successfully for fabricated silica network nanotubes.

Magnetic Nanoparticles Used in Oncology

Recently, magnetic nanoparticles (MNPs) have more and more often been used in experimental studies on cancer treatments, which have become one of the biggest challenges in medical research. The main goal of this research is to treat and to cure advanced or metastatic cancer with minimal side effects through nanotechnology. Drug delivery approaches take into account the fact that MNPs can be bonded to chemotherapeutical drugs, nucleic acids, synthetized antibodies or radionuclide substances. MNPs can be guided, and different treatment therapies can be applied, under the influence of an external magnetic field. This paper reviews the main MNPs’ synthesis methods, functionalization with different materials and highlight the applications in cancer therapy. In this review, we describe cancer cell monitorization based on different types of magnetic nanoparticles, chemotherapy, immunotherapy, magnetic hyperthermia, gene therapy and ferroptosis. Examples of applied treatments on murine models or humans are analyzed, and glioblastoma cancer therapy is detailed in the review. MNPs have an important contribution to diagnostics, investigation, and therapy in the so called theranostics domain. The main conclusion of this paper is that MNPs are very useful in different cancer therapies, with limited side effects, and they can increase the life expectancy of patients with cancer drug resistance.

Iron Oxide Nanorings and Nanotubes for Magnetic Hyperthermia: The Problem of Intraparticle Interactions

Magnetic interactions can play an important role in the heating efficiency of magnetic nanoparticles. Although most of the time interparticle magnetic interactions are a dominant source, in specific cases such as multigranular nanostructures intraparticle interactions are also relevant and their effect is significant. In this work, we have prepared two different multigranular magnetic nanostructures of iron oxide, nanorings (NRs) and nanotubes (NTs), with a similar thickness but different lengths (55 nm for NRs and 470 nm for NTs). In this way, we find that the NTs present stronger intraparticle interactions than the NRs. Magnetometry and transverse susceptibility measurements show that the NTs possess a higher effective anisotropy and saturation magnetization. Despite this, the AC hysteresis loops obtained for the NRs (0-400 Oe, 300 kHz) are more squared, therefore giving rise to a higher heating efficiency (maximum specific absorption rate, SARmax = 110 W/g for the NRs and 80 W/g for the NTs at 400 Oe and 300 kHz). These results indicate that the weaker intraparticle interactions in the case of the NRs are in favor of magnetic hyperthermia in comparison with the NTs.

Characterization and Inhibitory Effects of Magnetic Iron Oxide Nanoparticles Synthesized from Plant Extracts on HeLa Cells

Magnetic Fe₃O₄ nanoparticles were synthesized from maize leaves and plantain peels extract mediators. Particles were characterized, and the inhibitory effects were studied on HeLa cells in vitro using cyclic voltammetry (CV). Voltammograms from the CV show that Fe₃O₄ NPs interaction with HeLa cells affected their electrochemical behavior. The nanoparticles formed with higher Fe³⁺/Fe²⁺ molar ratio (2.8 : 1) resulted in smaller crystallite sizes compared to those formed with lower Fe³⁺/Fe²⁺ molar ratio (1.4 : 1). The particles with the smallest crystallite size showed higher anodic peak currents, whereas the larger crystallite sizes resulted in lower anodic peak currents. The peak currents relate to cell inhibition and are confirmed by the half-maximum inhibitory concentration (IC₅₀). The findings show that the particles have a different inhibitory mechanism on HeLa cells ion transfer and are promising to be further exploited for cancer treatment.

A facile synthesis of one-dimensional hierarchical magnetic metal silicate microtubes with enhanced adsorption performance

One-dimensional (1D) hierarchical magnetic hollow micro/nanotubes have attracted special attention in the field of adsorption owing to their high surface area, easy separation and short mass diffusion. Here, we report a facile approach for synthesizing one-dimensional hierarchical magnetic metal silicate microtubes through an extended Stöber method, carbonization treatment and subsequent hydrothermal reaction with metal ions in an alkaline solution. The unique 1D hierarchical magnetic microtubes have a large surface area, good structural stability and high magnetic response. Benefiting from these advantages, the resultant microtubes display excellent performance as good adsorbents for bovine hemoglobin (BHb) and methylene blue (MB). Furthermore, this strategy can also be applied to prepare other 1D hierarchical magnetic metal silicate composites.

The role of hollow magnetic nanoparticles in drug delivery

The increasing number of scientific publications focusing on nanomaterials in the biomedical field indicates growing interest from the broader scientific community. Nanomedicine is a modern science, and research continues into the application of nanoscale materials for the therapy and diagnosis of damaged tissues. In this regard, substantial progress has been made in the synthesis of magnetic materials with desired sizes, morphologies, chemical compositions, and surface chemistry. Among these, magnetic iron oxide nanoparticles have demonstrated great promise as unique carriers in the delivery of chemical drugs due to their combinations of hollow structures. Importantly, due to the combination of the ability to respond to an external magnetic field and the rich possibilities of their coatings, magnetic materials are universal tools for the magnetic separation of small molecules, biomolecules, and cells. This review provides an overview of the synthesis and biological applications of hollow magnetic nanoparticles in drug delivery systems.

Applications of cyclic peptide nanotubes (cPNTs)

Self-assembled cyclic peptide nanotubes (cPNTs) have recently drawn particular attention as one of the most intriguing nanostructures in the field of nanotechnology. Given their unique features including high surface area, increased drug loading, environmental stability, enhanced permeation, and modifiable drug release, these hollow tubular structures can be constructed with cyclic di-, tri-, tetra-, hexa-, octa-, and decapeptides with various amino acid sequences, enantiomers, and functionalized side chains and can be applied for antiviral and antibacterial drugs, drug delivery and gene delivery vectors, organic electronic devices, and ionic or molecular channels. Recent publications have presented promising results regarding the use of cPNTs as drugs or biomedical devices. However, there is an urgent need for the further in vivo nanotoxicity and safety testing of these nanotubes to evaluate their suitability in different fields.

Flower-Like Molybdenum Disulfide for Polarity-Triggered Accumulation/Release of Small Molecules

Flower-like molybdenum disulfide (MoS₂) with rich edge sites has been prepared by the hydrothermal method. The edge sites possess polarity due to the noncentrosymmetric Mo-S on exposed (100) facets and thus show a strong electrostatic attraction toward polar species. The flower-like MoS₂ can be used as small-molecule carriers for the model drug, Rhodamine B (RhB). The results prove that flower-like MoS₂ have fast adsorption kinetics and perform a switchable accumulation/release with response to the solvent polarity. An outstanding reusability can be found in flower-like MoS₂ due to little cargo retention, and the recycle of adsorption can be repeated 100 times with above 88.5% of the adsorption capacity retained. The flower-like MoS₂ with solvent polarity-triggered loading/release can be extended to controlled release and color switch of display.

Porous nanopeapod Pd catalyst with excellent stability and efficiency

Porous Pd@m-C/SiO₂ nanopeapods are prepared by a nanoconfinement method. The Pd nanoparticles show high efficiency and stability in chemical reactions such as reduction of nitrobenzene by H₂ and reduction of NO by NH₃. The high catalytic activity is attributed to the unique peapod structure, mesoporous wall, and large specific surface area on Pd@m-C/SiO₂ rendering the Pd nanoparticles highly active in chemical reactions.

BSA Protein-Mediated Synthesis of Hollow Mesoporous Silica Nanotubes, and Their Carbohydrate Conjugates for Targeting Cancer Cells and Detecting Mycobacteria

A straightforward method was developed to synthesize hollow mesoporous silica nanotubes (HMSNTs) using bovine serum protein (BSA) as the protective coating and phosphate buffered saline (PBS) as the etching agent at room temperature. Galactose-grafted HMSNTs significantly reduced phagocytosis by macrophages, and enhanced cellular uptake by A549 cells via caveolae-mediated uptake pathway. Trehalose-conjugated HMSNTs interacted strongly with mycobacteria, showing the linear detection range from 1 × 10⁴ to 1 × 10⁸ bacteria/mL and the detection limit of 1 × 10³ bacteria/mL. In all cases, the hollow nanotube structure showed higher cellular uptake, bacterial binding, and detection efficiency than their spherical counterpart.

Synthesis of Micelles Guided Magnetite (Fe3O4) Hollow Spheres and their application for AC Magnetic Field Responsive Drug Release

This paper reports on synthesis of hollow spheres of magnetite, guided by micelles and their application in drug release by the stimulus responsive technique. Here oleyelamine micelles are used as the core substance for the formation of magnetite nano hollow spheres (NHS). Diameter and shell thickness of NHS have been changed by changing concentration of the micelles. Mechanism of NHS formation has been established by investigating the aliquot collected at different time during the synthesis of NHS. It has been observed that oleyelamine as micelles play an important role to generate hollow-sphere particles of different diameter and thickness just by varying its amount. Structural analysis was done by XRD measurement and morphological measurements, SEM and TEM were performed to confirm the shape and size of the NHS. FTIR measurement support the formation of magnetite phase too. Frequency dependent AC magnetic measurements and AC magnetic field stimulated drug release event by these particles provide a direction of the promising application of these NHS for better cancer treatment in near future. Being hollow &porous in structure and magnetic in nature, such materials will also be useful in other applications such as in removal of toxic materials, magnetic separation etc.

Stimuli responsive drug delivery systems based on nano-graphene for cancer therapy

Nano-graphene as a class of two-dimensional sp² carbon nanomaterial has attracted tremendous attentions in various fields in the past decade. Utilizing its unique physical and chemical properties, nano-graphene has also shown great promises in the area of biomedicine, for application in biosensing, imaging and therapy. In particular, with all atoms exposed on its surface, nano-graphene exhibits ultra-high surface area available for efficient binding/loading of various biomolecules of interests, and has been widely used as multifunctional nano-carriers for drug and gene delivery. In this review article, we will summarize the recent advances in the development of nano-graphene as stimuli-responsive nano-carriers for drug delivery, as well as the applications of these smart systems for cancer therapy.

USPIO assisting degradation of MXC by host/guest-type immobilized laccase in AOT reverse micelle system

The laccase and ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) have been assembled inside the tubular mesoporous silica via co-adsorption technology to prepare host/guest-type immobilized laccase, which is applied to degrade methoxychlor (MXC) in aqueous and reverse micelle environments. The effects of various parameters on degradation of MXC were studied. Under the optimum conditions, the degradation rate could reach maximum value of 45.6 % and remain at 20.8 % after seven cycles. Moreover, the addition of small molecular compound 2, 2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) to the system could greatly improve the degradation efficiency. The MXC degradation process is a first-order reaction, and the activation energy of MXC degradation catalyzed by immobilized laccase (41.46 kJ mol(-1)) is relatively lower than that catalyzed by free laccase (44.91 kJ mol(-1)). Based on the degradation products measured by gas chromatograph-mass spectrometer (GC-MS) and nuclear magnetic resonance (NMR), the degradation mechanism of MXC has also been proposed.

Proteasome inhibitory, antioxidant, and synergistic antibacterial and anticandidal activity of green biosynthesized magnetic Fe3O4 nanoparticles using the aqueous extract of corn (Zea mays L.) ear leaves

Herein, Fe₃O₄ nanoparticles synthesized using aqueous extract of corn ear leaves were investigated for proteasome inhibitory activity, antioxidant activity, synergistic antibacterial, and anticandidal potential. The UV-Vis spectrum displayed an absorption band at 355 nm that indicated the formation of nano-sized Fe₃O₄ particles. Vibrating sample magnetometer analysis revealed its superparamagnetic nature. Fe₃O₄ nanoparticles exhibited strong proteasome inhibitory potential and antioxidant activity and exerted strong synergistic antibacterial and anticandidal activity. Its significant proteasome inhibitory potential could be useful in cancer treatment and drug delivery. Furthermore, strong antioxidant, antibacterial, and anticandidal activity make them a promising candidate for biomedical and pharmaceutical applications.

Magnetically triggered drug release from biocompatible microcapsules for potential cancer therapeutics

The drug release of two types of MLMs synchronizes the AMF switch; different mechanisms were discussed in this paper.

Multifunctional glucose biosensors from Fe₃O₄ nanoparticles modified chitosan/graphene nanocomposites

Novel water-dispersible and biocompatible chitosan-functionalized graphene (CG) has been prepared by a one-step ball milling of carboxylic chitosan and graphite. Presence of nitrogen (from chitosan) at the surface of graphene enables the CG to be an outstanding catalyst for the electrochemical biosensors. The resulting CG shows lower I_D/I_G ratio in the Raman spectrum than other nitrogen-containing graphene prepared using different techniques. Magnetic Fe₃O₄ nanoparticles (MNP) are further introduced into the as-synthesized CG for multifunctional applications beyond biosensors such as magnetic resonance imaging (MRI). Carboxyl groups from CG is used to directly immobilize glucose oxidase (GO_x) via covalent linkage while incorporation of MNP further facilitated enzyme loading and other unique properties. The resulting biosensor exhibits a good glucose detection response with a detection limit of 16 μM, a sensitivity of 5.658 mA/cm²/M, and a linear detection range up to 26 mM glucose. Formation of the multifunctional MNP/CG nanocomposites provides additional advantages for applications in more clinical areas such as in vivo biosensors and MRI agents.

Functionalization of nitrogen-doped carbon nanotubes with gallium to form Ga-CN(x)-multi-wall carbon nanotube hybrid materials

In an effort to combine group III-V semiconductors with carbon nanotubes, a simple solution-based technique for gallium functionalization of nitrogen-doped multi-wall carbon nanotubes has been developed. With an aqueous solution of a gallium salt (GaI(3)), it was possible to form covalent bonds between the Ga(3+) ion and the nitrogen atoms of the doped carbon nanotubes to form a gallium nitride-carbon nanotube hybrid at room temperature. This functionalization was evaluated by x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy.