Magnetic Biocompatible Photonic Crystals can be used both for Optics and Medicine
Magnetic Biocompatible Photonic Crystal can be used both for Optics and Medicine
Researchers at ITMO University developed a new approach for obtaining non-toxic magnetic Biocompatible Photonic Crystal, expanding their applications from mainly photonics to biomedicine. Nanospheres made with the new method may be used for designing drugs to fight thrombosis and cancer. The results of the research were published in Scientific reports.
Magnetic biocompatible photonic crystal (MPC) is basically a complex of nanoparticles that can selectively change its reflectance spectra under the influence of an applied magnetic field. Such crystals can be used in photonics for making optical fibers, filters and other applications. While application of such systems holds a high potential, there are some problems concerning the synthesis of MPC. This procedure requires sophisticated equipment, high temperature and pressure as well as highly toxic chemicals.
Scientists from ITMO University along with their colleagues from Saint Petersburg Electrotechnical University and N.N. Blokhin Russian Cancer Research Center suggested an inexpensive and simple method which enables MPC production in mild conditions and without toxic chemicals. The method is based on the controlled destabilization process of magnetic nanoparticles solution resulting in formation of larger nanocrystals. The key feature of the process is that the reagents used for this purposes are known to be non-toxic and are approved by FDA (Food and Drug Administration) and EMA (European Medical Agency) for parenteral administration. The resulting nanocrystals have similar sizes, excellent stability and are able to form periodic structures under the influence of magnetic fields. Such features make it possible to regulate the wavelength of light reflected by nanocrystals, which may be useful for constructing various sensory, communication and navigation systems.
Magnetic Biocompatible Photonic Crystal in biomedicine
Owing to their biocompatibility, such nanospheres can also be used in biomedicine for targeted drug delivery.
“Unlike its alternatives, our method is suitable for diverse fields rather than just for optics and photonics. Due to mild synthesis conditions we are able to modify our technique in order to incorporate drugs in the structure of nanospheres,” explains Andrey Drozdov, researcher at the SCAMT Laboratory in ITMO University. “We are currently working on drugs for thrombosis and breast cancer treatment. Since we avoid using toxic chemicals, such drugs are safe to inject into the body. As soon as they reach the required tissue we can apply a magnetic field to separate MNS and release the medicine with precision.”
Another advantage of the suggested method is flexibility. Controllable destabilization enables to obtain nanospheres from various materials or their mixtures.
“In this research we have used magnetite: iron oxide with a strong response to magnetic field. By adding other metal oxides, however, we could achieve hybrid nanospheres with features that were previously inconceivable,” says Andrey Drozdov.
Reference: “The controllable destabilization route for synthesis of low cytotoxic magnetic nanospheres with photonic response”
Y. I. Andreeva, A. S. Drozdov et al. Scientific reports Sep. 12, 2017
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The controllable destabilization route for synthesis of low cytotoxic magnetic nanospheres with photonic response
Biocompatible Photonic Crystal – magnetic photonic crystal (MPC) is basically a complex of nanoparticles that can selectively change its reflectance spectra under the influence of applied magnetic field. Such crystals can be used in photonics for making optical fibers, filters and other applications.
“We present a new approach for obtaining magnetic nanospheres with tunable size and high magnetization. The method is implemented via controllable destabilization of a stable magnetite hydrosol with glycerol, leading to the formation of aggregates followed by their stabilization with the citrate shell. This inexpensive, simple and easily scalable approach required no special equipment. The obtained samples were characterized by high stability and magnetization over 80 emu/g. Effects of synthetic conditions on physicochemical properties of nanospheres were monitored by hydrodynamic size, zeta potential, and polydispersity of magnetite aggregates. The size of the resulting aggregates varied between 650 nm and 40 nm, and the zeta potential from +30 mV to −43 mV by changing the ratio of the reagents. Under optimal conditions the clusters with a diameter of 80 nm were produced with a narrow size distribution ±3 nm. These characteristics allowed for optical response to the external magnetic field, thereby producing a magnetic photon liquid. Due to biocompatibility of the reagents used in the synthesis the nanospheres evoked a negligible cytotoxicity for human non-malignant and tumor cell lines. These results make new materials valuable in photonics and biomedicine.”
From: Biocompatible Photonic Crystal
Contributors: Yulia I. Andreeva, Andrey S. Drozdov, Anna F. Fakhardo, Nikolay A. Cheplagin, Alexander A. Shtil & Vladimir V. Vinogradov
Biocompatible Photonic Crystals can be used both for Optics and Medicine an introduction
Monodisperse magnetic nanospheres (MNS) are widely used in a variety of research and technological areas. Due to their unique physicochemical properties, the applications of these structures in biomedicine (e.g., for magnetic separation of bioobjects1,2,3,4, targeted drug delivery5,6,7,8,9,10, and MRI spectroscopy11, 12) is of particular interest. Also, MNS have prospects in optics and photonics13. Because of special requirements for these systems, studies were aimed at the synthesis of nanospheres with a hydrophilic functional surface to facilitate covalent cross-linking with biomolecules and stabilizers. The magnetic core consisting of aggregated nanoparticles provides high magnetization which is necessary for rapid manipulations and high signal sensitivity, the characteristics useful in photonic devices14,15,16,17and biomedicine18,19,20. To date, two main approaches to obtain MNS have been pursued. First, a one-pot method implies the formation of nanoparticles and their aggregation during synthesis. In particular, the hydrothermal method for synthesis of nanospheres with a high magnetite content gives very narrow size distribution21,22,23. For instance, it is possible to obtain MNS stabilized by sodium citrate in an autoclave at high temperature (above 200 °C) and pressure (13 790 kPa)24. Using this approach 60–200 nm MNS have been generated. By changing the reaction conditions and the ratio of components and stabilizers, one can vary the textural and optical properties of resulting systems in a wide range. Although this approach could be used to produce the systems with high colloid stability and photonic properties, it requires special equipment, harsh conditions such as a high pressure and temperature, and carcinogenic chemicals such as ethylene glycol and diethylene glycol, thereby limiting possible application scenario. Another procedure relies on a polyol synthesis of nanospheres with a high degree of magnetization and a narrow dispersion25. This process includes the oxidation-reduction reaction between the metal precursor and liquid polyols, usually ethylene glycol, acting as polar solvents and reducing agents. In this procedure the hydrophilic magnetic nanocrystals are synthesized in situ and simultaneously self-organize into compact clusters, this, in turn, results in a high magnetic response of the clusters. Polyols strongly affect the size and morphology of particles, which greatly complicates the management of physicochemical properties of MNS. Although this approach produces the systems with a high colloid stability and photonic response, they require special equipment for synthesis. Also, carcinogens such as ethylene glycol and diethylene glycol are used, thereby limiting the biomedical applications of synthesized materials. The second approach presumes the use of previously prepared nanoparticles as building blocks for constructing larger aggregates26, 27. A sol-gel method26implies that particles obtained at the first stage are covered with a silica coating, yielding nanospheres whose core consists of several magnetite particles with a silicon shell. This approach involves several stages and requires the second component that makes the synthesis much longer and contradicts the trend towards simplification of the composition. In addition, the silica shell significantly reduces the magnetic susceptibility of the material, making it hardly useful for magnetic delivery.All the above methods are considered ‘bottom-up’ approaches, in which the aggregation of ultrafine particles is achieved with stabilizers. In this study we present a new method for obtaining MNS by controllable destabilization of a stable magnetite hydrosol. This method leads to the formation of aggregates with various sizes followed by stabilization with the citrate shell. Our inexpensive, simple and easy-to-scale approach does not require any special equipment. Samples are highly stable. In addition to analyzing the sizes of the resulting structures, their stability and polydispersity, a particular attention is paid to 80 nm MNS that exhibit photonic properties at high concentrations in solution. At lower concentrations MNS behave similarly to magnetic nanoparticles (MNP) and quickly separate when an external magnetic field is applied. Rapid magnetic response and a negligibly low cytotoxicity provide evidence for a perspective of newly developed systems in photonics and biomedicine.
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From: Biocompatible Photonic Crystal