Magnetic Nanoparticles and Biosciences

Mechanical properties of cellulose nanofibril papers and their bionanocomposites: A review

Cellulose nanofibril (CNF) paper has various applications due to its unique advantages. Herein, we present the intrinsic mechanical properties of CNF papers, along with the preparation and properties of nanoparticle-reinforced CNF composite papers. The literature on CNF papers reveals a strong correlation between the intrafibrillar network structure and the resulting mechanical properties. This correlation is found to hold for all primary factors affecting mechanical properties, indicating that the performance of CNF materials depends directly on and can be tailored by controlling the intrafibrillar network of the system. The parameters that influence the mechanical properties of CNF papers were critically reviewed. Moreover, the effect on the mechanical properties by adding nanofillers to CNF papers to produce multifunctional composite products was discussed. We concluded this article with future perspectives and possible developments in CNFs and their bionanocomposite papers.

Optimization Study on Specific Loss Power in Superparamagnetic Hyperthermia with Magnetite Nanoparticles for High Efficiency in Alternative Cancer Therapy

The cancer therapy with the lowest possible toxicity is today an issue that raises major difficulties in treating malignant tumors because chemo- and radiotherapy currently used in this field have a high degree of toxicity and in many cases are ineffective. Therefore, alternative solutions are rapidly being sought in cancer therapy, in order to increase efficacy and a reduce or even eliminate toxicity to the body. One of the alternative methods that researchers believe may be the method of the future in cancer therapy is superparamagnetic hyperthermia (SPMHT), because it can be effective in completely destroying tumors while maintaining low toxicity or even without toxicity on the healthy tissues. Superparamagnetic hyperthermia uses the natural thermal effect in the destruction of cancer cells, obtained as a result of the phenomenon of superparamagnetic relaxation of the magnetic nanoparticles (SPMNPs) introduced into the tumor; SPMNPs can heat the cancer cells to 42-43 °C under the action of an external alternating magnetic field with frequency in the range of hundreds of kHz. However, the effectiveness of this alternative method depends very much on finding the optimal conditions in which this method must be applied during the treatment of cancer. In addition to the type of magnetic nanoparticles and the biocompatibility with the biological tissue or nanoparticles biofunctionalization that must be appropriate for the intended purpose a key parameter is the size of the nanoparticles. Also, establishing the appropriate parameters for the external alternating magnetic field (AMF), respectively the amplitude and frequency of the magnetic field are very important in the efficiency and effectiveness of the magnetic hyperthermia method. This paper presents a 3D computational study on specific loss power (Ps) and heating temperature (ΔT) which allows establishing the optimal conditions that lead to efficient heating of Fe₃O₄ nanoparticles, which were found to be the most suitable for use in superparamagnetic hyperthermia (SPMHT), as a non-invasive and alternative technique to chemo- and radiotherapy. The size (diameter) of the nanoparticles (D), the amplitude of the magnetic field (H) and the frequency (f) of AMF were established in order to obtain maximum efficiency in SPMHT and rapid heating of magnetic nanoparticles at the required temperature of 42-43 °C for irreversible destruction of tumors, without affecting healthy tissues. Also, an analysis on the amplitude of the AMF is presented, and how its amplitude influences the power loss and, implicitly, the heating temperature, observables necessary in SPMHT for the efficient destruction of tumor cells. Following our 3D study, we found for Fe₃O₄ nanoparticles the optimal diameter of ~16 nm, the optimal range for the amplitude of the magnetic field of 10-25 kA/m and the optimal frequency within the biologically permissible limit in the range of 200-500 kHz. Under the optimal conditions determined for the nanoparticle diameter of 16.3 nm, the magnetic field of 15 kA/m and the frequency of 334 kHz, the magnetite nanoparticles can be quickly heated to obtain the maximum hyperthermic effect on the tumor cells: in only 4.1-4.3 s the temperature reaches 42-43 °C, required in magnetic hyperthermia, with major benefits in practical application in vitro and in vivo, and later in clinical trials.

Heat Transfer Study in Breast Tumor Phantom during Microwave Ablation: Modeling and Experimental Results for Three Different Antennas

It is worldwide known that the most common type of cancer among women is breast cancer. Traditional procedures involve surgery, chemotherapy and radiation therapy; however, these treatments are invasive and have serious side effects. For this reason, minimally invasive thermal treatments like microwave ablation are being considered. In this study, thermal behavior of three types of slot-coaxial antennas for breast cancer microwave ablation is presented. By using finite element method (FEM), all antennas were modeled to estimate the heat transfer in breast tumor tissue surrounded by healthy breast tissue. Experimentation was carried out by using the antennas inserted inside sphere-shaped-tumor phantoms with two different diameters, 1.0 and 1.5 cm. A microwave radiation system was used to apply microwave energy to each designed antenna, which were located into the phantom. A non-interfering thermometry system was used to measure the temperature increase during the experimentation. Temperature increases, recorded by the thermal sensors placed inside the tumor phantom surrounded by healthy breast phantom, were used to validate the FEM models. The results conclude that, in all the cases, after 240 s, the three types of coaxial slot antenna reached the temperature needed produce hyperthermia of the tumor volume considered in this paper.

The Potential Biomedical Application of NiCu Magnetic Nanoparticles

Magnetic nanoparticles became increasingly interesting in recent years as a result of their tailorable size-dependent properties, which enable their use in a wide range of applications. One of their emerging applications is biomedicine; in particular, bimetallic nickel/copper magnetic nanoparticles (NiCu MNPs) are gaining momentum as a consequence of their unique properties that are suitable for biomedicine. These characteristics include stability in various chemical environments, proven biocompatibility with various cell types, and tunable magnetic properties that can be adjusted by changing synthesis parameters. Despite the obvious potential of NiCu MNPs for biomedical applications, the general interest in their use for this purpose is rather low. Nevertheless, the steadily increasing annual number of related papers shows that increasingly more researchers in the biomedical field are studying this interesting formulation. As with other MNPs, NiCu-based formulations were examined for their application in magnetic hyperthermia (MH) as one of their main potential uses in clinics. MH is a treatment method in which cancer tissue is selectively heated through the localization of MNPs at the target site in an alternating magnetic field (AMF). This heating destroys cancer cells only since they are less equipped to withstand temperatures above 43 °C, whereas this temperature is not critical for healthy tissue. Superparamagnetic particles (e.g., NiCu MNPs) generate heat by relaxation losses under an AMF. In addition to MH in cancer treatment, which might be their most beneficial potential use in biomedicine, the properties of NiCu MNPs can be leveraged for several other applications, such as controlled drug delivery and prolonged localization at a desired target site in the body. After a short introduction that covers the general properties of NiCu MNPs, this review explores different synthesis methods, along with their main advantages and disadvantages, potential surface modification approaches, and their potential in biomedical applications, such as MH, multimodal cancer therapy, MH implants, antibacterial activity, and dentistry.

Glass-ceramics for cancer treatment: So close, or yet so far?

After years of research on the ability of glass-ceramics in bone regeneration, this family of biomaterials has shown revolutionary potentials in a couple of emerging applications such as cancer treatment. Although glass-ceramics have not yet reached their actual potential in cancer therapy, the relevant research activity is significantly growing in this field. It has been projected that this idea and the advent of magnetic bioactive glass-ceramics and mesoporous bioactive glasses could result in major future developments in the field of cancer. Undoubtedly, this strategy needs further developments to better answer the critical questions essential for clinical usage. This review aims to address the existing research developments on glass-ceramics for cancer treatment, starting with the current status and moving to future advances. STATEMENT OF SIGNIFICANCE: Although glass-ceramics have not yet reached their potential in cancer therapy, research activity is significantly growing. It has been speculated that this idea and the advent of modern glass-ceramics could result in significant future advances. Undoubtedly, this strategy needs further investigations and many critical questions have to be answered before it can be successfully applied for cancer treatment. This paper reviews the current state-of-the-art, starting with current products and moving onto recent developments in this field. According to our knowledge, there is a lack of a systematic review on the importance and developments of magnetic bioactive glass-ceramics and mesoporous bioactive glasses for cancer treatment, and it is expected that this review will be of interest to those working in this area.

Next-generation nanoantibacterial tools developed from peptides

Bacteria resistant against various antimicrobial compounds have emerged in many countries, and the age of resistance has just started. Among the more promising novel antimicrobial compounds on which current research is focusing are the antimicrobial peptides (AMPs). These are often less susceptible to bacterial resistance since multiple modifications in the cellular membranes, cell wall and metabolism are required to reduce their effectiveness. Most likely, the use of pure AMPs will be insufficient for controlling pathogenic bacteria, and innovative approaches are required to employ AMPs in new antibiotic treatments. Therefore, here we review novel bionanotechnological approaches, including nanofibers, nanoparticles and magnetic particles for effectively using AMPs in fighting infectious diseases.

Solubilization, dispersion and stabilization of magnetic nanoparticles in water and non-aqueous solvents: recent trends

Solubilization and stabilization techniques for magnetic nanoparticles in water and in non-aqueous solvents are reviewed.

Hypothetical superparamagnetic magnetometer in a pigeon's upper beak probably does not work

We reanalysed the role of superparamagnetic magnetite clusters observed in a pigeon's upper beak to decide if this matter can be a component of some sort of pigeon magnetometer for Earth orientation. We investigated the mutual interaction of the magnetite clusters induced by the geomagnetic field. The force sensitivity of the hypothetical magnetometer in a pigeon's upper beak was estimated considering the previously presented threshold magnetic sensitivity of pigeons, measured in electrophysiological and behavioural investigations. The typical intercluster magnetic force seems to be 10(-19)N well above the threshold magnetic sensitivity. To strengthen our results, we measured the magnetic susceptibility of superparamagnetic magnetite using a vibrating sample magnetometer. Finally we performed theoretical kinematic analysis of the motion of magnetite clusters in cell plasma. The results indicate that magnetite clusters, constituted by superparamagnetic nanoparticles and observed in a pigeon's upper beak, may not be a component of a measuring system providing the magnetic map.

Clusters and lattices of particles stabilized by dipolar coupling

We model stabilization of clusters and lattices of spherical particles with dominant electric and magnetic dipolar coupling, and weak van der Waals coupling. Our analytical results demonstrate that dipolar coupling can stabilize nanoparticle clusters with planar, tubular, Möbius, and other arrangements. We also explain for which parameters the nanoparticles can form lattices with fcc, hcp, sh, sc, and other types of packing. Although these results are valid at different scales, we illustrate that realistic magnetic and semiconducting nanoparticles need to have certain minimum sizes to stabilize at room temperature into nanostructures controlled by dipolar coupling.

Charge binding of rhodamine derivative to OH- stabilized nanomaghemite: universal nanocarrier for construction of magnetofluorescent biosensors

Superparamagnetic nanoparticles (20-40 nm) of maghemite, γ-Fe(2)O(3), with well-defined stoichiometric structure, are synthesized by the borohydride reduction of ferric chloride at an elevated temperature (100°C) followed by thermal treatment of the reaction product. Prepared maghemite nanoparticles reveal excellent colloidal stability for a long time without the necessity for any additional surface modification. These colloidal features are due to surface stabilizing OH(-) groups, which act as charge barriers preventing a particle aggregation and enabling a reversible binding of various oppositely charged organic substances. Such binding with rhodamine B isothiocyanate results in the fluorescent magnetic nanocarrier providing, at the same time, a spacer arm for covalent immobilization of other biosubstances including enzymes. In this work, we exploit this general applicability of the developed nanocarrier for covalent immobilization of glucose oxidase. This is the first reported example of magnetically drivable fluorescent nanocatalyst. The immobilized enzyme creates a 3-5 nm thick layer on the nanoparticle surface as proved by high-resolution transmission electron microscopy. This layer corresponds to 10 enzyme molecules, which are bound to the nanoparticle surface as found by the fluorimetric determination of flavin adenine dinucleotide. The developed magnetic fluorescent nanocatalyst, showing a rate constant of 32.7s(-1) toward glucose oxidation, can be used as a biosensor in various biochemical, biotechnological, and food chemistry applications. The presence of the nanocatalyst can be simply monitored by its fluorescence; moreover, it can be easily separated from the solution by an external magnetic field and repeatedly used without a loss of catalytic efficiency.

Novel Applications of Ferrites

The applications of ferrimagnetic oxides, or ferrites, in the last 10 years are reviewed, including thin films and nanoparticles. The general features of the three basic crystal systems and their magnetic structures are briefly discussed, followed by the most interesting applications in electronic circuits as inductors, in high-frequency systems, in power delivering devices, in electromagnetic interference suppression, and in biotechnology. As the field is considerably large, an effort has been made to include the original references discussing each particular application on a more detailed manner.

The Influence of Water Content on the Morphology and Magnetic Properties of Nickel Nanoparticles Prepared in Reverse Microemulsion

Magnetic nickel nanoparticles are prepared by NaBH4reducing agent in AOT reverse microemulsion, the influence of water content on the morphology and magnetic properties of nickel nanoparticles are investigated by TEM study, size distribution, XRD characterization and magnetization curves. The results show that spherical and polydispered particles are obtained in microemulsion. The dimension and polydispersity of particles increased with the increasing of water content. Magnetization curves clearly indicate a ferromagnetic behavior with high coercivity values. At water content of W0=41.7, the product has a high saturated magnetization 70.68 emu/g with its residual magnetizations 28.02 emu/g, higher than the sample obtained at water content of W0=13.9.

Structural and magnetic properties of ternary Fe(1-)MnPt nanoalloys from first principles

BACKGROUND

Structural and magnetic properties of binary Mn-Pt and ternary Fe(1-) (x)Mn(x)Pt nanoparticles in the size range of up to 2.5 nm (561 atoms) have been explored systematically by means of large scale first principles calculations in the framework of density functional theory. For each composition several magnetic and structural configurations have been compared.

RESULTS

The concentration dependence of magnetization and structural properties of the ternary systems are in good agreement with previous bulk and thin film measurements. At an intermediate Mn-content around x = 0.25 a crossover between several phases with magnetic and structural properties is encountered, which may be interesting for exploitation in functional devices.

CONCLUSION

Addition of Mn effectively increases the stability of single crystalline L1(0) particles over multiply twinned morphologies. This, however, compromises the stability of the ferromagnetic phase due to an increased number of antiferromagnetic interactions. The consequence is that only small additions of Mn can be tolerated for data recording applications.

Photonic immobilization of BSA for nanobiomedical applications: creation of high density microarrays and superparamagnetic bioconjugates

Light assisted molecular immobilization has been used for the first time to engineer covalent bioconjugates of superparamagnetic nanoparticles and proteins. The technology involves disulfide bridge disruption upon UV excitation of nearby aromatic residues. The close spatial proximity of aromatic residues and disulfide bridges is a conserved structural feature in proteins. The created thiol groups bind thiol reactive surfaces leading to oriented covalent protein immobilization. We have immobilized a model carrier protein, bovine serum albumin, onto Fe(3)O(4)@Au core-shell nanoparticles as well as arrayed it onto optically flat thiol reactive surfaces. This new immobilization technology allows for ultra high dense packing of different bio-molecules on a surface, allowing the creation of multi-potent functionalized active new biosensor materials, biomarkers identification and the development of nanoparticles based novel drug delivery system.

Cylinders vs. spheres: biofluid shear thinning in driven nanoparticle transport

Increasingly, the research community applies magnetophoresis to micro and nanoscale particles for drug delivery applications and the nanoscale rheological characterization of complex biological materials. Of particular interest is the design and transport of these magnetic particles through entangled polymeric fluids commonly found in biological systems. We report the magnetophoretic transport of spherical and rod-shaped particles through viscoelastic, entangled solutions using lambda-phage DNA (λ-DNA) as a model system. In order to understand and predict the observed phenomena, we fully characterize three fundamental components: the magnetic field and field gradient, the shape and magnetic properties of the probe particles, and the macroscopic rheology of the solution. Particle velocities obtained in Newtonian solutions correspond to macroscale rheology, with forces calculated via Stokes Law. In λ-DNA solutions, nanorod velocities are 100 times larger than predicted by measured zero-shear viscosity. These results are consistent with particles experiencing transport through a shear thinning fluid, indicating magnetically driven transport in shear thinning may be especially effective and favor narrow diameter, high aspect ratio particles. A complete framework for designing single-particle magnetic-based delivery systems results when we combine a quantified magnetic system with qualified particles embedded in a characterized viscoelastic medium.

Magnetic Biotransport: Analysis and Applications

Magnetic particles are finding increasing use in bioapplications, especially as carrier particles to transport biomaterials such as proteins, enzymes, nucleic acids and whole cells etc. Magnetic particles can be prepared with biofunctional coatings to target and label a specific biomaterial, and they enable controlled manipulation of a labeled biomaterial using an external magnetic field. In this review, we discuss the use of magnetic nanoparticles as transport agents in various bioapplications. We provide an overview of the properties of magnetic nanoparticles and their functionalization for bioapplications. We discuss the basic physics and equations governing the transport of magnetic particles at the micro- and nanoscale. We present two different transport models: a classical Newtonian model for predicting the motion of individual particles, and a drift-diffusion model for predicting the behavior of a concentration of nanoparticles that takes into account Brownian motion. We review specific magnetic biotransport applications including bioseparation, drug delivery and magnetofection. We demonstrate the transport models via application to these processes.