Photo-fluorescent and magnetic properties of iron oxide nanoparticles for biomedical applications

Detection of tetanus toxoid with iron magnetic nanobioprobe

Diagnosis of diseases with low facilities, speed, accuracy and sensitivity is an important matter in treatment. Bioprobes based on iron oxide nanoparticles are a good candidate for early detection of deadly and infectious diseases such as tetanus due to their high reactivity, biocompatibility, low production cost and sample separation under a magnetic field. In this study, silane groups were coated on surface of iron oxide nanoparticles using tetraethoxysilane (TEOS) hydrolysis. Also, NH2groups were generated on the surface of silanized nanoparticles using 3-aminopropyl triethoxy silane (APTES). Antibody was immobilized on the surface of silanized nanoparticles using TCT trichlorothriazine as activator. Silanization and stabilized antibody were investigated by using of FT-IR, EDX, VSM, SRB technique. UV/vis spectroscopy, fluorescence, agglutination test and ELISA were used for biosensor performance and specificity. The results of FT-IR spectroscopy showed that Si-O-Si and Si-O-Fe bonds and TCT chlorine and amine groups of tetanus anti-toxoid antibodies were formed on the surface of iron oxide nanoparticles. The presence of Si, N and C elements in EDX analysis confirms the silanization of iron oxide nanoparticles. VSM results showed that the amount of magnetic nanoparticles after conjugation is sufficient for biological applications. Antibody stabilization on nanoparticles increased the adsorption intensity in the uv/vis spectrometer. The fluorescence intensity of nano bioprobe increased in the presence of 10 ng ml-1. Nanobio probes were observed as agglomerates in the presence of tetanus toxoid antigen. The presence of tetanus antigen caused the formation of antigen-nanobioprobe antigen complex. Identification of this complex by HRP-bound antibody confirmed the specificity of nanobioprobe. Tetanus magnetic nanobioprobe with a diagnostic limit of 10 ng ml-1of tetanus antigen in a short time can be a good tool in LOC devices and microfluidic chips.

Compact, remote optical waveguide magnetic field sensing using double-pass Faraday rotation-induced optical attenuation

Compact, magnetic field, B sensing is proposed and demonstrated by combining the two Faraday rotation elements and beam displacement crystals within a micro-optical fiber circulator with a fiber reflector and ferromagnets to allow high contrast attenuation in an optical fiber arm. Low optical noise sensing is measured at λ=1550n m as a change in attenuation, α, of optical light propagating through the rotators and back. The circulator's double-pass configuration, using a gold mirror as a reflector, achieves a magnetic field sensitivity s=Δ α/Δ B=(0.26±0.02)d B/m T with a resolution of Δ B=0.01m T, over a detection range B=0-89m T. The circulator as a platform provides direct connectivity to the Internet, allowing remote sensing to occur. The method described here is amenable to multisensor combinations, including with other sensor technologies, particularly in future integrated waveguide Faraday optical circuits and devices, extending its utility beyond point magnetic field sensing applications.

Investigation of background, novelty and recent advance of iron (II,III) oxide- loaded on 3D polymer based scaffolds as regenerative implant for bone tissue engineering: A review

Bone tissue engineering had crucial role in the bone defects regeneration, particularly when allograft and autograft procedures have limitations. In this regard, different types of scaffolds are used in tissue regeneration as fundamental tools. In recent years, magnetic scaffolds show promising applications in different biomedical applications (in vitro and in vivo). As superparamagnetic materials are widely considered to be among the most attractive biomaterials in tissue engineering, due to long-range stability and superior bioactivity, therefore, magnetic implants shows angiogenesis, osteoconduction, and osteoinduction features when they are combined with biomaterials. Furthermore, these scaffolds can be coupled with a magnetic field to enhance their regenerative potential. In addition, magnetic scaffolds can be composed of various combinations of magnetic biomaterials and polymers using different methods to improve the magnetic, biocompatibility, thermal, and mechanical properties of the scaffolds. This review article aims to explain the use of magnetic biomaterials such as iron (II,III) oxide (Fe2O3 and Fe3O4) in detail. So it will cover the research background of magnetic scaffolds, the novelty of using these magnetic implants in tissue engineering, and provides a future perspective on regenerative implants.

Recent advances in functionalized ferrite nanoparticles: From fundamentals to magnetic hyperthermia cancer therapy

Cancers are fatal diseases that lead to most death of human beings, which urgently require effective treatments methods. Hyperthermia therapy employs magnetic nanoparticles (MNPs) as heating medium under external alternating magnetic field. Among various MNPs, ferrite nanoparticles (FNPs) have gained significant attention for hyperthermia therapy due to their exceptional magnetic properties, high stability, favorable biological compatibility, and low toxicity. The utilization of FNPs holds immense potential for enhancing the effectiveness of hyperthermia therapy. The main hurdle for hyperthermia treatment includes optimizing the heat generation capacity of FNPs and controlling the local temperature of tumor region. This review aims to comprehensively evaluate the magnetic hyperthermia treatment (MHT) of FNPs, which is accomplished by elucidating the underlying mechanism of heat generation and identifying influential factors. Based upon fundamental understanding of hyperthermia of FNPs, valuable insights will be provided for developing efficient nanoplatforms with enhanced accuracy and magnetothermal properties. Additionally, we will also survey current research focuses on modulating FNPs' properties, external conditions for MHT, novel technical methods, and recent clinical findings. Finally, current challenges in MHT with FNPs will be discussed while prospecting future directions.

Magnetic nanoparticles fabricated/integrated with microfluidics for biological applications: A review

Nanostructured materials have gained significant attention in recent years for their potential in biological applications, such as cell and biomolecular sorting, as well as early detection of metastatic cancer. Among these materials, magnetic nanoparticles (MNPs) stand out for their easy functionalization, high specific surface area, chemical stability, and superparamagnetic properties. However, conventional fabrication methods can lead to inconsistencies in MNPs' characteristics and performance, highlighting the need for a cost-effective, controllable, and reproducible synthesis approach. In this review, we will discuss the utilization of microfluidic technology as a cutting-edge strategy for the continuous and regulated synthesis of MNPs. This approach has proven effective in producing MNPs with a superior biomedical performance by offering precise control over particle size, shape, and surface properties. We will examine the latest research findings on developing and integrating MNPs synthesized through continuous microfluidic processes for a wide range of biological applications. By providing an overview of the current state of the field, this review aims to showcase the advantages of microfluidics in the fabrication and integration of MNPs, emphasizing their potential to revolutionize diagnostic and therapeutic methods within the realm of biotechnology.

Probing analysis of Cu-doping on the structural, optical, morphological and magnetic properties of hematite nanoparticles and their antibacterial activity

The present study describes the synthesis of pure and Cu doped α-Fe2O3nanoparticles (with various concentrations of Copper 1, 3, 6, and 9 wt%) by conventional chemical precipitation technique and examines their structural, morphological, optical, magnetic, and antibacterial capabilities. The XRD pattern of pure and Cu-doped α-Fe2O3 nanoparticles exhibit rhombohedral structure and the estimated crystalline sizes were ranged from 39 to 58 nm. It is discovered that the estimated density dislocations linked to the agglomeration/cluster formations diminish when interstitial vacancies are filled with copper. The obtained bandgap from Tauc's plot, 2.07 eV of pure α-Fe2O3 is found to less than Cu doped α-Fe2O3 nanoparticles (2.9-3.4 eV), due to the structural changes and the tailing of localised states into deep bandgap energy levels. The intense blue emission bands (410-490 nm) arised due to the movement of trapped electrons from the donor level to the valance band and broad green emission bands (522-560 nm) are due to deep level CuO defect to the Fe2O3. The fundamental stretching of Fe-O vibrations and the presence of Cu in prepared samples were identified in FTIR and Raman spectra. SEM micrograph shows the uniform distribution of spherical nanoparticles with size ranged from 39 to 61 nm, which is in good accord with XRD studies. Further, the magnetic characteristics of the pure and Cu-doped α-Fe2O3 samples were assessed using a vibrating sample magnetometer (VSM); the ensuing hysteresis loop of the Cu-doped α-Fe2O3 displays weaker ferromagnetic behaviour. In the present investigations, the disc diffusion technique has been used to examine the antibacterial activity. Thus, the results of antibacterial activities demonstrated that at concentrations of 200 and 500 μg/ml of pure and Cu-doped α-Fe2O3 NPs, the highest zone of inhibition was found against gram (+ve) positive bacteria and was followed by the gram (-ve) negative bacteria's.

Investigation of Photoluminescence and Optoelectronics Properties of Transition Metal-Doped ZnO Thin Films

Thin films of zinc oxide (ZnO) doped with transition metals have recently gained significant attention due to their potential applications in a wide range of optoelectronic devices. This study focuses on ZnO thin films doped with the transition metals Co, Fe, and Zr, exploring various aspects of their structural, morphological, optical, electrical, and photoluminescence properties. The thin films were produced using RF and DC co-sputtering techniques. The X-ray diffraction (XRD) analysis revealed that all the doped ZnO thin films exhibited a stable wurtzite crystal structure, showcasing a higher structural stability compared to the undoped ZnO, while the atomic force microscopy (AFM) imaging highlighted a distinctive granular arrangement. Energy-dispersive X-ray spectroscopy was employed to confirm the presence of transition metals in the thin films, and Fourier-transform infrared spectroscopy (FTIR) was utilized to investigate the presence of chemical bonding. The optical characterizations indicated that doping induced changes in the optical properties of the thin films. Specifically, the doped ZnO thin film's bandgap experienced a significant reduction, decreasing from 3.34 to 3.30 eV. The photoluminescence (PL) analysis revealed distinguishable emission peaks within the optical spectrum, attributed to electronic transitions occurring between different bands or between a band and an impurity. Furthermore, the introduction of these transition metals resulted in decreased resistivity and increased conductivity, indicating their positive influence on the electrical conductivity of the thin films. This suggests potential applications in solar cells and light-emitting devices.

Interactions between gold nanoparticles with different morphologies and human serum albumin

Introduction: Three different shapes of gold nanoparticles were synthesized in this experiment. At the same time, studies compared their effects with human serum albumin (HSA). Methods: Gold nanoparticles (AuNPs) with three different morphologies, such as, nanospheres (AuNSs), nanorods (AuNRs), and nanoflowers (AuNFs) were synthesized via a seeding method and their characteristic absorption peaks were detected using ultraviolet-visible (UV-vis) absorption spectroscopy, Telectron microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta potential measurements, circular dichroism (CD), and Fourier transform infrared spectroscopy (FTIR) to study the interactions between them and HSA. By comparing the thermodynamic parameters and quenching mechanism of the three materials, similarities and differences were determined in their interactions with HSA. Results: The results showed that with an increase in the concentration of the AuNPs with the three different morphologies, the UV-vis absorption peak intensity of the mixed solution increased, but its fluorescence intensity was quenched. This indicates that the three types of AuNPs interact with HSA, and that the interactions between them represent a static quenching process, which is consistent with the conclusions derived from three-dimensional fluorescence experiments. Through variable-temperature fluorescence experiments, the binding constants, number of binding sites, and thermodynamic parameters of the interactions between the three types of AuNPs and HSA were determined. The Gibbs free energy changes were <0, indicating that the reactions of the three types of AuNPs with HSA are spontaneous, resulting in associated matter. Binding constant measurements indicated that the strongest binding took place between the AuNFs and HSA. In addition, the results of fluorescence, CD spectroscopy, and FTIR showed that three different shapes of AuNPs can induce conformational changes in HSA and reduce the α-helix content. Among them, AuNFs have the smallest ability to induce conformational changes. Discussion: According to studies, AuNFs interact more favorably with HSA. This can be used as a reference for the administration of drugs containing AuNPs.

A review on the effect of nanocomposite scaffolds reinforced with magnetic nanoparticles in osteogenesis and healing of bone injuries

Many problems related to disorders and defects of bone tissue caused by aging, diseases, and injuries have been solved by the multidisciplinary research field of regenerative medicine and tissue engineering. Numerous sciences, especially nanotechnology, along with tissue engineering, have greatly contributed to the repair and regeneration of tissues. Various studies have shown that the presence of magnetic nanoparticles (MNPs) in the structure of composite scaffolds increases their healing effect on bone defects. In addition, the induction of osteogenic differentiation of mesenchymal stem cells (MSCs) in the presence of these nanoparticles has been investigated and confirmed by various studies. Therefore, in the present article, the types of MNPs, their special properties, and their application in the healing of damaged bone tissue have been reviewed. Also, the molecular effects of MNPs on cell behavior, especially in osteogenesis, have been discussed. Finally, the present article includes the potential applications of MNP-containing nanocomposite scaffolds in bone lesions and injuries. In summary, this review article highlights nanocomposite scaffolds containing MNPs as a solution for treating bone defects in tissue engineering and regenerative medicine.

Quantification methods of determining brewer's and pharmaceutical yeast cell viability: accuracy and impact of nanoparticles

For industrial processes, a fast, precise, and reliable method of determining the physiological state of yeast cells, especially viability, is essential. However, an increasing number of processes use magnetic nanoparticles (MNPs) for yeast cell manipulation, but their impact on yeast cell viability and the assay itself is unclear. This study tested the viability of Saccharomyces pastorianus ssp. carlsbergensis and Pichia pastoris by comparing traditional colourimetric, high-throughput, and growth assays with membrane fluidity. Results showed that methylene blue staining is only reliable for S. pastorianus cells with good viability, being erroneous in low viability (R² = 0.945; [Formula: see text] = 5.78%). In comparison, the fluorescence microscopy-based assay of S. pastorianus demonstrated a coefficient of determination of R² = 0.991 at [Formula: see text] ([Formula: see text] = 2.50%) and flow cytometric viability determination using carboxyfluorescein diacetate (CFDA), enabling high-throughput analysis of representative cell numbers; R² = 0.972 ([Formula: see text]; [Formula: see text] = 3.89%). Membrane fluidity resulted in a non-linear relationship with the viability of the yeast cells ([Formula: see text]). We also determined similar results using P. pastoris yeast. In addition, we demonstrated that MNPs affected methylene blue staining by overestimating viability. The random forest model has been shown to be a precise method for classifying nanoparticles and yeast cells and viability differentiation in flow cytometry by using CFDA. Moreover, CFDA and membrane fluidity revealed precise results for both yeasts, also in the presence of nanoparticles, enabling fast and reliable determination of viability in many experiments using MNPs for yeast cell manipulation or separation.

Processing and Physicochemical Properties of Magnetite Nanoparticles Coated with Curcuma longa L. Extract

In this work, Curcuma longa L. extract has been used in the synthesis and direct coating of magnetite (Fe₃O₄) nanoparticles ~12 nm, providing a surface layer of polyphenol groups (-OH and -COOH). This contributes to the development of nanocarriers and triggers different bio-applications. Curcuma longa L. is part of the ginger family (Zingiberaceae); the extracts of this plant contain a polyphenol structure compound, and it has an affinity to be linked to Fe ions. The nanoparticles' magnetization obtained corresponded to close hysteresis loop M_s = 8.81 emu/g, coercive field H_c = 26.67 Oe, and low remanence energy as iron oxide superparamagnetic nanoparticles (SPIONs). Furthermore, the synthesized nanoparticles (G-M@T) showed tunable single magnetic domain interactions with uniaxial anisotropy as addressable cores at 90-180°. Surface analysis revealed characteristic peaks of Fe 2p, O 1s, and C 1s. From the last one, it was possible to obtain the C-O, C=O, -OH bonds, achieving an acceptable connection with the HepG2 cell line. The G-M@T nanoparticles do not induce cell toxicity in human peripheral blood mononuclear cells or HepG2 cells in vitro, but they can increase the mitochondrial and lysosomal activity in HepG2 cells, probably related to an apoptotic cell death induction or to a stress response due to the high concentration of iron within the cell.

Photonic and magnetic materials for on-demand local drug delivery

Nanomedicine has been considered a promising tool for biomedical research and clinical practice in the 21st century because of the great impact nanomaterials could have on human health. The generation of new smart nanomaterials, which enable time- and space-controlled drug delivery, improve the limitations of conventional treatments, such as non-specific targeting, poor biodistribution and permeability. These smart nanomaterials can respond to internal biological stimuli (pH, enzyme expression and redox potential) and/or external stimuli (such as temperature, ultrasound, magnetic field and light) to further the precision of therapies. To this end, photonic and magnetic nanoparticles, such as gold, silver and iron oxide, have been used to increase sensitivity and responsiveness to external stimuli. In this review, we aim to report the main and most recent systems that involve photonic or magnetic nanomaterials for external stimulus-responsive drug release. The uniqueness of this review lies in highlighting the versatility of integrating these materials within different carriers. This leads to enhanced performance in terms of in vitro and in vivo efficacy, stability and toxicity. We also point out the current regulatory challenges for the translation of these systems from the bench to the bedside, as well as the yet unresolved matter regarding the standardization of these materials.

Enhanced fluorescent iron oxide quantum dots for rapid and interference free recognizing lysine in dairy products

In this work, a simple, easy and selective method for sensing lysine in an acidic medium was developed based on fluorescent iron oxide quantum dots (IO QDs). IO QDs using the hydrothermal method were prepared with different conditions (concentration of NPs, amount of citric acid, heating time, heating temperature, and total volume in the hydrothermal reactor) where iron oxide nanoparticles (IO NPs) were used as the starting materials. TEM, FTIR, UV-Vis Spectrometry, fluorescence spectrometry, Powder XRD, VSM were used to characterize the as-prepared IO QDs. The surface of the IO QDs contained -OH, -COO^-, and other functional groups that acted as a bridge to bind the IO QDs nanoprobe with the surrounding analytes. Under acidic conditions (pH 3.0), IO QDs exhibited a rapid and interference-free fluorescence enhancement behavior after adding lysine within 2 min at room temperature, whereas other amino acids had no effect on IO QDs fluorescence. Therefore, the IO QDs prepared in this study have shown potential in lysine sensing applications. The results showed that the relative FL intensity was linear with lysine concentration in the range of 1-100 μM and had a detection limit of 0.66 μM. This proposed method has high selectivity for lysine over other amino acids, and the developed methods were used in real sample with good recoveries. Under relatively acidic conditions, a specific and fast lysine interaction was observed, resulting in the successful of IO QDs as the fluorescent probe for rapid and interference-free lysine assessment in dairy products.

Rapid and sensitive magnetic field sensor based on photonic crystal fiber with magnetic fluid infiltrated nanoholes

A fast response time (0.1 s) magnetic field sensor has been demonstrated utilizing a photonic crystal fiber with nano-size air holes infiltrated with polyethylene glycol based magnetic fluid. The effect of magnetic nanoparticles concentration in the fluid on the magneto-optical sensor performance and its dependence under varying magnetic-field loads was investigated in detail. In particular, the sensor response was analytically modelled with a Langevin function with a good fit (R\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge $$\end{document}≥0.996). A threshold sensing point as low as 20 gauss was recorded and a detection range of 0–350 gauss was demonstrated by means of optical transmission measurements. The experimental results were validated by theory using a waveguide light transmission model fed by finite-element method simulations of the principal guided modes in the infiltrated fiber sensor. The simple interrogation scheme, high sensitivity and quick response time makes the proposed hybrid fiber-optic magneto-fluidic probe a promising platform for novel biochemical sensing applications.

Internal heating method of loop-mediated isothermal amplification for detection of HPV-6 DNA

Loop-mediated isothermal amplification (LAMP) is a promising diagnostic tool for genetic amplification, which is known for its rapid process, simple operation, high amplification efficiency, and excellent sensitivity. However, most of the existing heating methods are external for completion of molecular amplification with possibility of contamination of specimens. The present research provided an internal heating method for LAMP using magnetic nanoparticles (MNPs), which is called nano-LAMP. Near-infrared light with an excitation wavelength of 808 nm was employed as the heating source; hydroxy naphthol blue (HNB) was used as an indicator to conduct methodological research. We demonstrate that the best temperature was controlled at a working power of 2 W and 4.8 µg/µL concentration of nanoparticles. The lowest limit for the detection of HPV by the nano-LAMP method is 10² copies/mL, which was confirmed by a gel electrophoresis assay. In the feasibility investigation of validated clinical samples, all 10 positive HPV-6 specimens amplified by nano-LAMP were consistent with conventional LAMP methods. Therefore, the nano-LAMP detection method using internal heating of MNPs may bring a new vision to the exploration of thermostatic detection in the future.

Photo-induced processes of iron oxide nanoparticles to enhance laser therapy

Nanoparticles are used as drug carriers to increase the selectivity and effectiveness of therapy, as well as for combined therapy that utilizes different effects. Iron oxide nanoparticles are promising in this aspect. Due to magnetic properties, they can be used as a contrast agent for magnetic resonance imaging. Also, iron oxide nanoparticles could be coated with a photosensitizer for photodynamic therapy and their laser or magnetic heating can be used for phototherapy. Local enhancement of the electromagnetic field near iron oxide nanoparticles can increase the fluorescence intensity of photosensitizers and the efficiency of singlet oxygen generation. This paper presents the results of a study of iron oxide nanoparticles focused on the photophysical aspects of the formation of “hot spots” under laser irradiation. The photoinduced effects of iron oxide nanoparticles observed in in vitro experiments lead to the rupture of lysosomes. Theoretical modeling showed that the heating of iron oxide nanoparticles with a radius of 35 nm under the action of laser radiation is about 89°C and 19°C for wavelengths of 458 and 561 nm, respectively. Local field enhancement occurs in pairs of nanoparticles of various sizes and strongly depends on the distance between them. The maximum gain is achieved at small distances between nanoparticles. For a dimer of nanoparticles with radii of 10 and 35 nm at a distance of 1 nm, an enhancement factor of two orders of magnitude was obtained. The investigated phenomenon of «hot spots» is in demand for precision therapy, because the photo-induced processes occur at small distances between nanoparticles, in areas of their high accumulation.

Visible light photocatalysts from low-grade iron ore: the environmentally benign production of magnetite/carbon (Fe3O4/C) nanocomposites

Magnetite (Fe₃O₄) nanoparticles coated with dextrose and gluconic acid possessing both super-paramagnetism and excellent optical properties have been productively synthesized through a straightforward, efficient and cost-efficient hydrothermal reduction route using Fe³⁺ as sole metal precursor acquired from accumulated iron ore tailings-a mining waste that usually represents a major environmental threat. Fe₃O₄/C nanocomposites were fully elucidated by FEGSEM and TEM, revealing a combination of platelets (<1 μm) capped by particles (<10 nm) and magnetite which was verified by XPS, which demonstrated also oxygen deficiency. A dextrose/gluconic acid coating was elucidated by Fourier transform-infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The Fe₃O₄/C nanocomposites were found to be superparamagnetic at room temperature. Meanwhile, their optical properties were investigated by UV-visible diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy; an E_g of 1.86 eV was determined, and emissions at 612 and 650 nm (ex. 250 nm) were consistent with the XPS identification of oxygen vacancies. The efficacy of the as-synthesized magnetically recoverable magnetite/carbon (Fe₃O₄/C) nanocomposites has been exhibited in the photocatalytic degradation of the toxic textile (industrial) dye bodactive red BNC-BS.

Stimuli-responsive nanomaterials for cancer treatment: boundaries, opportunities and applications

Small molecule drugs, including most chemotherapies, are rapidly degraded and/or eliminated from the body, which is why high doses of these drugs are necessary, potentially producing toxic effects. Several types of nanoparticles loaded with anti-cancer drugs have been designed to overcome the disadvantages of conventional therapies. Modified nanoparticles can circulate for a long time, thus improving the solubility and biodistribution of drugs. Furthermore, they also allow the controlled release of the payload once its target tissue has been reached. These mechanisms can reduce the exposure of healthy tissues to chemotherapeutics, since the drugs are only released in the presence of specific tumour stimuli. Overall, these properties can improve the effectiveness of treatments while reducing undesirable side effects. In this article, we review the recent advances in stimuli-responsive albumin, gold and magnetic nanostructures for controlled anti-cancer drug delivery. These nanostructures were designed to release drugs in response to different internal and external stimuli of the cellular environment, including pH, redox, light and magnetic fields. We also describe various examples of applications of these nanomaterials. Overall, we shed light on the properties, potential clinical translation and limitations of stimuli-responsive nanoparticles for cancer treatment.

Unique emissive behavior of combustion-derived particles under illumination with femtosecond pulsed near-infrared laser light

Exposure to combustion-derived particles (CDPs), such as carbonaceous particulate matter (PM), has adverse effects on human health. Hence, selective detection of these particles in biological environments is required to understand their toxicity. The optical detection of carbonaceous PM is possible in biological samples based on white light (WL) emission under illumination with a femtosecond (fs) pulsed near-infrared (NIR) laser. However, it is unclear if common non-CDPs in ambient PM, such as silica and metal oxides, can interfere with CDP detection when illuminated using a fs-pulsed NIR laser. Here, we show that WL emission, when illuminated with a fs-pulsed NIR laser, is observed only for CDPs amongst other common air pollution particles. We report that the intense WL emission from CDPs spanning over the whole visible spectrum is not observed from non-CDPs. This observation is made for four different CDPs and five different, relevant non-CDPs, in wet and dried samples using biologically relevant imaging conditions. This investigation confirms the uniqueness of WL emission as a selective detection mechanism of CDPs using a multiphoton microscopy platform, commonly available in research laboratories. Furthermore, some relevant signatures for the non-CDPs are provided that could potentially lead to the selective monitoring of pollution related nanoparticles (NPs).

Radio frequency plasma assisted surface modification of Fe3O4 nanoparticles using polyaniline/polypyrrole for bioimaging and magnetic hyperthermia applications

Surface modification of superparamagnetic Fe₃O₄ nanoparticles using polymers (polyaniline/polypyrrole) was done by radio frequency (r.f.) plasma polymerization technique and characterized by XRD, TEM, TG/DTA and VSM. Surface-passivated Fe₃O₄ nanoparticles with polymers were having spherical/rod-shaped structures with superparamagnetic properties. Broad visible photoluminescence emission bands were observed at 445 and 580 nm for polyaniline-coated Fe₃O₄ and at 488 nm for polypyrrole-coated Fe₃O₄. These samples exhibit good fluorescence emissions with L929 cellular assay and were non-toxic. Magnetic hyperthermia response of Fe₃O₄ and polymer (polyaniline/polypyrrole)-coated Fe₃O₄ was evaluated and all the samples exhibit hyperthermia activity in the range of 42-45 °C. Specific loss power (SLP) values of polyaniline and polypyrrole-coated Fe₃O₄ nanoparticles (5 and 10 mg/ml) exhibit a controlled heat generation with an increase in the magnetic field.

Numerical Investigation of Ferrofluid Preparation during In-Vitro Culture of Cancer Therapy for Magnetic Nanoparticle Hyperthermia

Recently, in-vitro studies of magnetic nanoparticle (MNP) hyperthermia have attracted significant attention because of the severity of this cancer therapy for in-vivo culture. Accurate temperature evaluation is one of the key challenges of MNP hyperthermia. Hence, numerical studies play a crucial role in evaluating the thermal behavior of ferrofluids. As a result, the optimum therapeutic conditions can be achieved. The presented research work aims to develop a comprehensive numerical model that directly correlates the MNP hyperthermia parameters to the thermal response of the in-vitro model using optimization through linear response theory (LRT). For that purpose, the ferrofluid solution is evaluated based on various parameters, and the temperature distribution of the system is estimated in space and time. Consequently, the optimum conditions for the ferrofluid preparation are estimated based on experimental and mathematical findings. The reliability of the presented model is evaluated via the correlation analysis between magnetic and calorimetric methods for the specific loss power (SLP) and intrinsic loss power (ILP) calculations. Besides, the presented numerical model is verified with our experimental setup. In summary, the proposed model offers a novel approach to investigate the thermal diffusion of a non-adiabatic ferrofluid sample intended for MNP hyperthermia in cancer treatment.

Magnetic nanoparticles for cancer theranostics: Advances and prospects

Cancer is one of the leading causes of mortality worldwide. Nanoparticles have been broadly studied and emerged as a novel approach in diagnosis and treatment of tumors. Over the last decade, researches have significantly improved magnetic nanoparticle (MNP)'s theranostic potential as nanomedicine for cancer. Newer MNPs have various advantages such as wider operating temperatures, smaller sizes, lower toxicity, simpler preparations and lower production costs. With a series of unique and superior physical and chemical properties, MNPs have great potential in medical applications. In particular, using MNPs as probes for medical imaging and carriers for targeted drug delivery systems. While MNPs are expected to be the future of cancer diagnosis and precision drug delivery, more research is still required to minimize their toxicity and improve their efficacy. An ideal MNP for clinical applications should be precisely engineered to be stable to act as tracers or deliver drugs to the targeted sites, release drug components only at the targeted sites and have minimal health risks. Our review aims to consolidate the recent improvements in MNPs for clinical applications as well as discuss the future research prospects and potential of MNPs in cancer theranostics.

Probing of Interactions of Magnetite Nanoparticles Coated with Native and Aminated Starch with a DPPC Model Membrane

Understanding the mechanism of interactions between magnetite nanoparticles and phospholipids that form cellular membranes at the molecular level is of crucial importance for their safe and effective application in medicine (e.g. magnetic resonance imaging, targeted drug delivery, and hyperthermia-based anticancer therapy). In these interactions, their surface coating plays a crucial role because even a small modification to its structure can cause significant changes to the behaviour of the magnetite nanoparticles that come in contact with a biomembrane. In this work, the influence of the magnetite nanoparticles functionalized with native and aminated starch on the thermodynamics, morphology, and dilatational elasticity of the model cell membranes was studied. The model cell membranes constituted the Langmuir monolayers formed at the air-water interface of dipalmitoylphosphatidylcholine (DPPC). The surface of the aminated starch-coated nanoparticles was enriched in highly reactive amino groups, which allowed more effective binding of drugs and biomolecules suitable for specific nano-bio applications. The studies indicated that the presence of these groups also reduced to some extent the disruptive effect of the magnetite nanoparticles on the model membranes and improved their adsorption.

Hydrogel with silver nanoparticles synthesized by Mimosa tenuiflora for second-degree burns treatment

In this work we use Mimosa tenuiflora (MtE) extracts as reducing agents to synthesize silver nanoparticles (AgMt NPs) which were characterized by DPPH and Total Polyphenols Assays, UV-visible, X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TGA). AgMt NPs possess average sizes of 21 nm and fcc crystalline structure, it was also confirmed that the MtE is present in the AgMt NPs even after the cleaning protocol applied. Subsequently, carbopol hydrogels were made and the MtE and the synthesized AgMt NPs were dispersed in different gels (MtE-G and AgMt NPs-G, respectively) at 100 µg/g concentration. The gels were characterized by UV-Vis, IR, and rheology. Antimicrobial tests were performed using Staphylococcus aureus and Escherichia coli. Burn wound healing was evaluated in a second-degree burn injury on a Wistar rats model for 14 days and additional skin biopsies were examined with histopathological analysis. Gel with commercial silver nanoparticles (Ag NPs) was prepared and employed as a control on the biological assays. Hydrogel system containing silver nanoparticles synthesized with Mimosa tenuiflora (AgMt NPs-G) is a promising therapeutic strategy for burn wound healing, this due to bactericidal and anti-inflammatory effects, which promotes a more effective recovery (in percentage terms) by damaged area.

Selective Detection of Cancer Cells Using Magnetic Nanowires

The main bottleneck for implementing magnetic nanowires (MNWs) in cell-biology research for multimodal therapeutics is the inapplicability of the current state of the art for selective detection and stimulation of MNWs. Here, we introduce a methodology for selective detection of MNWs in platforms that have multiple magnetic signals, such as future multimodal therapeutics. After characterizing the signatures of MNWs, MNWs were surface-functionalized and internalized into canine osteosarcoma (OSCA-8) cancer cells for cell labeling, manipulation, and separation. We also prepared and characterized magnetic biopolymers as multimodal platforms for future use in controlling the movement, growth, and division of cancer cells. First, it is important to have methods for distinguishing the magnetic signature of the biopolymer from the magnetically labeled cells. For this purpose, we use the projection method to selectively detect and demultiplex the magnetic signatures of MNWs inside cells from those inside magnetic biopolymers. We show that tailoring the irreversible switching field of MNWs by tuning their coercivity is a highly effective approach for generating distinct magnetic biolabels for selective detection of cancer cells. These findings open up new possibilities for selective stimulation of MNWs in multimodal therapeutic platforms for drug delivery, hyperthermia cancer therapy, and mitigating cancer cell movement and proliferation.

Iron oxide nanoparticles conjugated with organic optical probes for in vivo diagnostic and therapeutic applications

The role and scope of functional inorganic nanoparticles in biomedical research is well established. Among these, iron oxide nanoparticles (IONPs) have gained maximum attention as they can provide targeting, imaging and therapeutic capabilities. Furthermore, incorporation of organic optical probes with IONPs can significantly enhance the scope and viability of their biomedical applications. Combination of two or more such applications renders multimodality in nanoparticles, which can be exploited to obtain synergistic benefits in disease detection and therapy viz theranostics, which is a key trait of nanoparticles for advanced biomedical applications. This review focuses on the use of IONPs conjugated with organic optical probe/s for multimodal diagnostic and therapeutic applications in vivo.

Light-Interacting iron-based nanomaterials for localized cancer detection and treatment

To improve the prognosis of cancer patients, methods of local cancer detection and treatment could be implemented. For that, iron-based nanomaterials (IBN) are particularly well-suited due to their biocompatibility and the various ways in which they can specifically target a tumor, i.e. through passive, active or magnetic targeting. Furthermore, when it is needed, IBN can be associated with well-known fluorescent compounds, such as dyes, clinically approved ICG, fluorescent proteins, or quantum dots. They may also be excited and detected using well-established optical methods, relying on scattering or fluorescent mechanisms, depending on whether IBN are associated with a fluorescent compound or not. Systems combining IBN with optical methods are diverse, thus enabling tumor detection in various ways. In addition, these systems provide a wealth of information, which is inaccessible with more standard diagnostic tools, such as single tumor cell detection, in particular by combining IBN with near-field scanning optical microscopy, dark-field microscopy, confocal microscopy or super-resolution microscopy, or the highlighting of certain dynamic phenomena such as the diffusion of a fluorescent compound in an organism, e.g. using fluorescence lifetime imaging, fluorescence resonance energy transfer, fluorescence anisotropy, or fluorescence tomography. Furthermore, they can in some cases be complemented by a therapeutic approach to destroy tumors, e.g. when the fluorescent compound is a drug, or when a technique such as photo-thermal or photodynamic therapy is employed. This review brings forward the idea that iron-based nanomaterials may be associated with various optical techniques to form a commercially available toolbox, which can serve to locally detect or treat cancer with a better efficacy than more standard medical approaches. STATEMENT OF SIGNIFICANCE: New tools should be developed to improve cancer treatment outcome. For that, two closely-related aspects deserve to be considered, i.e. early tumor detection and local tumor treatment. Here, I present various types of iron-based nanomaterials, which can achieve this double objective when they interact with a beam of light under specific and accurately chosen conditions. Indeed, these materials are biocompatible and can be used/combined with most standard microscopic/optical methods. Thus, these systems enable on the one hand tumor cell detection with a high sensitivity, i.e. down to single tumor cell level, and on the other hand tumor destruction through various mechanisms in a controlled and localized manner by deciding whether or not to apply a beam of light and by having these nanomaterials specifically target tumor cells.

Silk Fibroin Coated Magnesium Oxide Nanospheres: A Biocompatible and Biodegradable Tool for Noninvasive Bioimaging Applications

Fluorescent nanoparticles (NPs) have been increasingly studied as contrast agents for better understanding of biological processes at the cellular and molecular level. However, their use as bioimaging tools is strongly dependent on their optical emission as well as their biocompatibility. This work reports the fabrication and characterization of silk fibroin (SF) coated magnesium oxide (MgO) nanospheres, containing oxygen, Cr³⁺ and V²⁺ related optical defects, as a nontoxic and biodegradable hybrid platform for bioimaging applications. The MgO-SF spheres demonstrated enhanced emission efficiency compared to noncoated MgO NPs. Furthermore, SF sphere coating was found to overcome agglomeration limitations of the MgO NPs. The hybrid nanospheres were investigated as an in vitro bioimaging tool by recording their cellular uptake, trajectories, and mobility in human skin keratinocytes cells (HaCaT), human glioma cells (U87MG) and breast cancer cells (MCF7). Enhanced cellular uptake and improved intracellular mobilities of MgO-SF spheres compared to MgO NPs was demonstrated in three different cell lines. Validated infrared and bright emission of MgO-SF NP indicate their prospects for in vivo imaging. The results identify the potential of the hybrid MgO-SF nanospheres for bioimaging. This study may also open new avenues to optimize drug delivery through biodegradable silk and provide noninvasive functional imaging feedback on the therapeutic processes through fluorescent MgO.

Surface engineered iron oxide nanoparticles as efficient materials for antibiofilm application

Overuse of antibiotics has led to the development of multi drug resistant strains. Antibiotic resistance is a major drawback in the biomedical field since medical implants are prone to infection by biofilms of antibiotic resistant strains of bacteria. With increasing prevalence of antibiotic resistant pathogenic bacteria, the search for alternative method is utmost importance. In this regard, magnetic nanoparticles are commonly used as a substitute for antibiotics that can circumvent the problem of biofilms growth on the surface of biomedical implants. Iron oxide nanoparticles (IONPs) have unique magnetic properties that can be exploited in various ways in the biomedical applications. IONPs are engineered employing different methods to induce surface functionalization that include the use of polyethyleneimine and oleic acid. IONPs have a mechanical effect on biofilms when in presence of an external magnet. In this review, a detailed description of surface engineered magnetic nanoparticles as ideal antibacterial agents is provided, accompanied by various methods of literature review. This article is protected by copyright. All rights reserved.

Hybrid Nanosystems for Biomedical Applications

Inorganic/organic hybrid nanosystems have been increasingly developed for their versatility and efficacy at overcoming obstacles not readily surmounted by nonhybridized counterparts. Currently, hybrid nanosystems are implemented for gene therapy, drug delivery, and phototherapy in addition to tissue regeneration, vaccines, antibacterials, biomolecule detection, imaging probes, and theranostics. Though diverse, these nanosystems can be classified according to foundational inorganic/organic components, accessory moieties, and architecture of hybridization. Within this Review, we begin by providing a historical context for the development of biomedical hybrid nanosystems before describing the properties, synthesis, and characterization of their component building blocks. Afterward, we introduce the architectures of hybridization and highlight recent biomedical nanosystem developments by area of application, emphasizing hybrids of distinctive utility and innovation. Finally, we draw attention to ongoing clinical trials before recapping our discussion of hybrid nanosystems and providing a perspective on the future of the field.

Reversible Diels-Alder Reactions with a Fluorescent Dye on the Surface of Magnetite Nanoparticles

Diels–Alder reactions on the surface of nanoparticles allow a thermoreversible functionalization of the nanosized building blocks. We report the synthesis of well-defined magnetite nanoparticles by thermal decomposition reaction and their functionalization with maleimide groups. Attachment of these dienophiles was realized by the synthesis of organophosphonate coupling agents and a partial ligand exchange of the original carboxylic acid groups. The functionalized iron oxide particles allow a covalent surface attachment of a furfuryl-functionalized rhodamine B dye by a Diels–Alder reaction at 60 °C. The resulting particles showed the typical fluorescence of rhodamine B. The dye can be cleaved off the particle surface by a retro-Diels–Alder reaction. The study showed that organic functions can be thermoreversibly attached onto inorganic nanoparticles.

Magnetic particles encoding a suspension probe for ultra-sensitive and quantitative determination of atrazine

As a highly toxic and widely used herbicide, atrazine poses a serious threat to food safety as well as overall environmental and human health. Due to complex matrix interference and the difficulty of signal enrichment, there is an urgent need for a convenient, fast, and ultrasensitive method that detects trace atrazine without concern for matrix effects. Here, we provide the first account of a sensitive and rapid suspension probe based on magnetic microspheres used to detect atrazine in herbs. The self-made magnetic beads featured -COOH groups and were used as the carrier to construct immunofluorescent probes. These probes then conjugated with the atrazine antigen through an activated ester method, ultimately binding to the antibody. Homogeneous detection was ensured using flow cytometry and the microflow optical channel along with allophycocyanin-conjugated goat-anti-mouse secondary antibody (APC-IgG-SecAb) as the fluorescent signal. The magnetic suspension probe allowed for high target enrichment and the inherent two-dimensional selective detection of flow cytometry effectively avoided any matrix interference. This method had good linearity across 1.69-23.19 ng mL^-1. The IC₅₀ and LOD values were 4.81 ng mL^-1 and 0.95 ng mL^-1, respectively; the sensitivity was increased three-fold relative to ELISA. After complete optimization, 2-N-morpholinoeth-anesulfonic acid was used as the coupling solution and maintained good mono-dispersity, stability, and reactivity for the labelled microspheres during the process. The entire experiment was simple, and effectively used reagents; moreover, both the labor required and detection time were greatly reduced. Critically, the strategy presented here greatly reduced interference from complex matrices, and saved preparation for matrix-matched solutions when different herbs were screened. Overall, this strategy was sensitive, rapid, eco-friendly, and labor-saving; collectively, these attributes make it well-suited for on-site screening of atrazine contamination and will allow for increased food safety.

Preparation of magnetized iron oxide grafted on graphene oxide for hyperthermia application

Magnetic hyperthermia therapy (MHT) is a highly promising therapeutic modality for the treatment of different kinds of cancers and malignant tumors. The therapy is based on the concept that; iron oxide nanoparticles deposited at cancer sites can generate heat when exposed to an alternating current magnetic field or near infrared radiation and consequently destroying only the cancer cells by exploiting their vulnerability to heat. The fact that the treatment is at molecular level and that iron oxide nanoparticles provide more guided focus heating justifies its efficacy over treatment such as surgery, radiation therapy and chemotherapy. Nevertheless, the spread of MHT as the next-generation therapeutics has been shadowed by insufficient heating especially at the in vivo stage. This can be averted by modifying the iron oxide nanoparticle structure. To this end, various attempts have been made by developing a magnetic hybrid nanostructure capable of generating efficient heat. However, the synthesis method for each component (of the magnetic hybrid nanostructure) and the grafting process is now an issue. This has a direct effect on the performance of the magnetic hybrid nanostructure in MHT and other applications. The main objective of this review is to detail out the different materials, methods and characterization techniques that have been used so far in developing magnetic hybrid nanostructure. In view of this, we conducted a comprehensive review and present a road map for developing a magnetic hybrid nanostructure that is capable of generating optimum heat during MHT. We further summarize the various characterization techniques and necessary parameters to study in validating the efficiency of the magnetic hybrid nanostructure. Hopefully, this contribution will serve as a guide to researchers that are willing to evaluate the properties of their magnetic hybrid nanostructure.

Self-Assembly Fabrication of Honeycomb-like Magnetic-Fluorescent Fe3O4-QDs Nanocomposites for Bimodal Imaging

Magnetic-fluorescent nanocomposites have a tremendous potential in biomedicine realms as a revolutionary dual-modality probe tool for more accurate medical detection. However, complicated and inefficient postprocesses pose obstacles to obtaining high-quality magnetic-fluorescent nanocomposites. Thus, the fabrication of magnetic-fluorescent functional nanocomposites via a simple, effective, and ideal method remains a challenge and is still waiting to be tapped. The new synthesis approaches are becoming impending demands and probably enable us to address these above-mentioned problems. In this contribution, we present a novel self-assembly synthesis route for the construction of magnetic-fluorescent bimodal imaging nanocomposites rather than adopting sophisticated postpreparative processes. The Fe₃O₄ and quatum dots (QDs) nanocomposites were cross-linked fleetly by cerium(III) ion driven coordination bonds in which the cerium(III) ions served as the cross-connecting node and the carboxylate groups acted as bridging ligands. The potential application for dual-modality imaging capability was validated on tumor-bearing mice. This ingenious strategy was extremely efficient and handy for the magnetic-fluorescent Fe₃O₄-QDs nanocomposite construction. Significantly, our cerium(III) ion driven self-assembly method probably has a wide applicability for nanoparticles and organic molecules containing carboxyl groups but extensive explorations are still necessary.

Magnetite (Fe3O4) Nanoparticles in Biomedical Application: From Synthesis to Surface Functionalisation

Nanotechnology has gained much attention for its potential application in medical science. Iron oxide nanoparticles have demonstrated a promising effect in various biomedical applications. In particular, magnetite (Fe3O4) nanoparticles are widely applied due to their biocompatibility, high magnetic susceptibility, chemical stability, innocuousness, high saturation magnetisation, and inexpensiveness. Magnetite (Fe3O4) exhibits superparamagnetism as its size shrinks in the single-domain region to around 20 nm, which is an essential property for use in biomedical applications. In this review, the application of magnetite nanoparticles (MNPs) in the biomedical field based on different synthesis approaches and various surface functionalisation materials was discussed. Firstly, a brief introduction on the MNP properties, such as physical, thermal, magnetic, and optical properties, is provided. Considering that the surface chemistry of MNPs plays an important role in the practical implementation of in vitro and in vivo applications, this review then focuses on several predominant synthesis methods and variations in the synthesis parameters of MNPs. The encapsulation of MNPs with organic and inorganic materials is also discussed. Finally, the most common in vivo and in vitro applications in the biomedical world are elucidated. This review aims to deliver concise information to new researchers in this field, guide them in selecting appropriate synthesis techniques for MNPs, and to enhance the surface chemistry of MNPs for their interests.

A Highly Magnetic Field Sensitive Photonic Crystal Fiber Based on Surface Plasmon Resonance

A novel magnetic field sensor comprising a photonic crystal fiber (PCF) is designed and investigated based on surface plasmon resonance (SPR). We use finite element analysis in order to analyze the sensing characteristics of the magnetic field sensor. The simulation results show that the sensor is very sensitive to the change of refractive index and has good linearity in the refractive index range from 1.43–1.45. The thickness of the metal film and the metal material has great influence on the resonance wavelength and the peak of the loss spectrum, the diameter of the central air hole will affect SPP excitation. When the thickness of gold layer is 50 nm, the refractive index sensitivity is 4125 nm/RIU in the refractive index range from 1.43–1.45. Using the designed sensor for magnetic field sensing, the loss spectrum is red-shifted with the increase of the magnetic field, the highest magnetic field sensitivity can reach 61.25 pm/Oe in the range from 50 Oe to 130 Oe. The sensor not only has high sensitivity of refractive index, but it can also realize accurate measurement of magnetic field. It has huge application potential in complex environment, remote sensing, real-time monitoring, and other fields.

Selective magnetometry of superparamagnetic iron oxide nanoparticles in liquids

We show that the properties of superparamagnetic iron oxide nanoparticles suspended in liquids can be effectively studied using Magnetic Circular Dichroism in Resonant Inelastic X-ray Scattering. Analysis of the spectral shape and magnetic contrast produced by this experiment enables an assessment of the site distribution and magnetic state of metal ions in the spinel phase. The selective magnetization profile of particles as derived from the field dependence of dichroism empowers an estimation of particle size distribution. Furthermore, the new proposed methodology discriminates sizes that are below the detection limits of X-ray and light scattering probes and that are difficult to spot in TEM.

Simultaneous Monitoring of Multi-Enzyme Activity and Concentration in Tumor Using a Triply Labeled Fluorescent In Vivo Imaging Probe

The use of fluorescent imaging probes that monitor the activity of proteases that experience an increase in expression and activity in tumors is well established. These probes can be conjugated to nanoparticles of iron oxide, creating a multimodal probe serving as both a magnetic resonance imaging (MRI) agent and an indicator of local protease activity. Previous works describe probes for cathepsin D (CatD) and metalloproteinase-2 (MMP2) protease activity grafted to cross-linked iron oxide nanoparticles (CLIO). Herein, we have synthesized a triply labeled fluorescent iron oxide nanoparticle molecular imaging (MI) probe, including an AF750 substrate concentration reporter along with probes for cathepsin B (CatB) sand MMP2 protease activity. The reporter provides a baseline signal from which to compare the activity of the two proteases. The activity of the MI probe was verified through incubation with the proteases and tested in vitro using the human HT29 tumor cell line and in vivo using female nude mice injected with HT29 cells. We found the MI probe had the appropriate specificity to the activity of their respective proteases, and the reporter dye did not activate when incubated in the presence of only MMP2 and CatB. Probe fluorescent activity was confirmed in vitro, and reporter signal activation was also noted. The fluorescent activity was also visible in vivo, with injected HT29 cells exhibiting fluorescence, distinguishing them from the rest of the animal. The reporter signal was also observable in vivo, which allowed the signal intensities of the protease probes to be corrected; this is a unique feature of this MI probe design.

Spatial focusing of magnetic particle hyperthermia

Magnetic particle hyperthermia is a promising cancer therapy, but a typical constraint of its applicability is localizing heat solely to malignant regions sparing healthy surrounding tissues. By simultaneous application of a constant magnetic field together with the hyperthermia inducing alternating magnetic field, heating focus may be confined to smaller regions in a tunable manner. The main objective of this work is to evaluate the focusing parameters, by adequate selection of magnetic nanoparticles and field conditions, and explore spatially focused magnetic particle hyperthermia efficiency in tissue phantom systems comprising agarose gel and magnetic nanoparticles. Our results suggest the possibility of spatially focused heating efficiency of magnetic nanoparticles through the application of a constant magnetic field. Tuning of the constant magnetic field parameters may result in minimizing thermal shock in surrounding regions without affecting the beneficiary thermal outcome in the focusing region.

Projection method as a probe for multiplexing/demultiplexing of magnetically enriched biological tissues

The unmet demand for cheap, accurate, and fast multiplexing of biomarkers has urged nanobiotechnology to prioritize the invention of new biomarkers that make feasible the remote detection, identification, and quantification of biological units, such as regenerative tissues. Here, we introduce a novel approach that highlights magnetic nanowires (MNWs) with such capabilities. This method employs the stable magnetization states of MNWs as a unique characteristic that can be realized by projecting the MNWs' switching field on the backward field (P_Hb), also known as the irreversible switching field. Experimentally, several types of MNWs were directly synthesized inside polycarbonate tissues and their P_Hb characteristics were measured and analyzed. Our results show that the P_Hb gives an excellent identification and quantification characteristic for demultiplexing MNWs embedded in these tissues. Furthermore, this method significantly improves the characterization speed by a factor of 50×–100× that makes it superior to the current state of the art that ceased the progression of magnetic nanoparticles in multiplexing/demultiplexing applications.

Different polycarbonate tissues were enriched using magnetic nanowires with diverse magnetic signatures. Projection method successfully identifies and quantifies the complex combinations of the magnetically enriched polycarbonate tissues.

Dynamics of interacting magnetic nanoparticles: effective behavior from competition between Brownian and Néel relaxation

The intriguing properties of magnetic nanoparticles have sparked a growing number of theoretical studies as well as practical applications. Here, we provide the first comprehensive study of the influence of interactions on the two main relaxation mechanisms: internal (Néel) and Brownian relaxation. While non-interacting magnetic nanoparticles show Debye behavior with an effective relaxation time, many authors use this model also for the interacting case. Since Néel relaxation is typically a thermally activated process on times scales that are many orders of magnitude larger than the underlying micromagnetic times, we use extensive computer simulations employing a Brownian dynamics/Monte-Carlo algorithm to show that dipolar interactions lead to significant deviations from the Debye behavior. We find that Néel and Brownian relaxation can be considered as independent processes for short enough times until dipolar interactions lead to a coupling of these mechanisms, making the interpretation more difficult. We provide mean-field arguments that describe these short and long-time, effective relaxation times well for weak up to moderate interaction strengths. Our findings about the coupling of Brownian and Néel process and the effective relaxation time provide an important theoretical insight that will have also important consequences for the interpretation of magnetic susceptibility measurements and magnetorelaxometry analysis.

Superparamagnetic iron oxide nanoparticulate system: synthesis, targeting, drug delivery and therapy in cancer

Cancer is a global epidemic and is considered a leading cause of death. Various cancer treatments such as chemotherapy, surgery, and radiotherapy are available for the cure but those are generally associated with poor long-term survival rates. Consequently, more advanced and selective methods that have better outcomes, fewer side effects, and high efficacies are highly in demand. Among these is the use of superparamagnetic iron oxide nanoparticles (SPIONs) which act as an innovative kit for battling cancer. Low cost, magnetic properties and toxicity properties enable SPIONs to be widely utilized in biomedical applications. For example, magnetite and maghemite (Fe3O4 and γ-Fe2O3) exhibit superparamagnetic properties and are widely used in drug delivery, diagnosis, and therapy. These materials are termed SPIONs when their size is smaller than 20 nm. This review article aims to provide a brief introduction on SPIONs, focusing on their fundamental magnetism and biological applications. The quality and surface chemistry of SPIONs are crucial in biomedical applications; therefore an in-depth survey of synthetic approaches and surface modifications of SPIONs is provided along with their biological applications such as targeting, site-specific drug delivery and therapy.