Makis Angelakeris

Bio: Makis Angelakeris is an academic researcher from Aristotle University of Thessaloniki. The author has contributed to research in topics: Magnetic nanoparticles & Magnetic hyperthermia. The author has an hindex of 11, co-authored 22 publications receiving 1014 citations.

Learning from Nature to Improve the Heat Generation of Iron-Oxide Nanoparticles for Magnetic Hyperthermia Applications

Abstract: The performance of magnetic nanoparticles is intimately entwined with their structure, mean size and magnetic anisotropy. Besides, ensembles offer a unique way of engineering the magnetic response by modifying the strength of the dipolar interactions between particles. Here we report on an experimental and theoretical analysis of magnetic hyperthermia, a rapidly developing technique in medical research and oncology. Experimentally, we demonstrate that single-domain cubic iron oxide particles resembling bacterial magnetosomes have superior magnetic heating efficiency compared to spherical particles of similar sizes. Monte Carlo simulations at the atomic level corroborate the larger anisotropy of the cubic particles in comparison with the spherical ones, thus evidencing the beneficial role of surface anisotropy in the improved heating power. Moreover we establish a quantitative link between the particle assembling, the interactions and the heating properties. This knowledge opens new perspectives for improved hyperthermia, an alternative to conventional cancer therapies.

Multiplying Magnetic Hyperthermia Response by Nanoparticle Assembling

Abstract: The oriented attachment of magnetic nanoparticles is recognized as an important pathway in the magnetic-hyperthermia cancer treatment roadmap, thus, understanding the physical origin of their enhanced heating properties is a crucial task for the development of optimized application schemes. Here, we present a detailed theoretical analysis of the hysteresis losses in dipolar-coupled magnetic nanoparticle assemblies as a function of both the geometry and length of the array, and of the orientation of the particles’ magnetic anisotropy. Our results suggest that the chain-like arrangement biomimicking magnetotactic bacteria has the superior heating performance, increasing more than 5 times in comparison with the randomly distributed system when aligned with the magnetic field. The size of the chains and the anisotropy of the particles can be correlated with the applied magnetic field in order to have optimum conditions for heat dissipation. Our experimental calorimetrical measurements performed in aqueous and...

Adjustable Hyperthermia Response of Self-Assembled Ferromagnetic Fe-MgO Core–Shell Nanoparticles by Tuning Dipole–Dipole Interactions

Abstract: The Fe-MgO core-shell morphology is proposed within the single-domain nanoparticle regime as an enhanced magnetically driven hyperthermia carrier. The combinatory use of metallic iron as a core material together with the increased particle size (37–65 nm) triggers the tuning of dipolar interactions between particles and allows for further enhancement of their collective heating effi ciency via concentration control. A theoretical universal estimation of hysteresis losses reveals the role of dipolar interactions on heating effi ciency and outlines the strong infl uence of coupling effects on hyperthermia opening a novel roadmap towards multifunctional heat-triggered theranostics particles.

In-situ particles reorientation during magnetic hyperthermia application: Shape matters twice.

Abstract: Promising advances in nanomedicine such as magnetic hyperthermia rely on a precise control of the nanoparticle performance in the cellular environment. This constitutes a huge research challenge due to difficulties for achieving a remote control within the human body. Here we report on the significant double role of the shape of ellipsoidal magnetic nanoparticles (nanorods) subjected to an external AC magnetic field: first, the heat release is increased due to the additional shape anisotropy; second, the rods dynamically reorientate in the orthogonal direction to the AC field direction. Importantly, the heating performance and the directional orientation occur in synergy and can be easily controlled by changing the AC field treatment duration, thus opening the pathway to combined hyperthermic/mechanical nanoactuators for biomedicine. Preliminary studies demonstrate the high accumulation of nanorods into HeLa cells whereas viability analysis supports their low toxicity and the absence of apoptotic or necrotic cell death after 24 or 48 h of incubation.

A Physically Transient Form of Silicon Electronics

Abstract: A remarkable feature of modern silicon electronics is its ability to remain physically invariant, almost indefinitely for practical purposes. Although this characteristic is a hallmark of applications of integrated circuits that exist today, there might be opportunities for systems that offer the opposite behavior, such as implantable devices that function for medically useful time frames but then completely disappear via resorption by the body. We report a set of materials, manufacturing schemes, device components, and theoretical design tools for a silicon-based complementary metal oxide semiconductor (CMOS) technology that has this type of transient behavior, together with integrated sensors, actuators, power supply systems, and wireless control strategies. An implantable transient device that acts as a programmable nonantibiotic bacteriocide provides a system-level example.

Water-soluble iron oxide nanocubes with high values of specific absorption rate for cancer cell hyperthermia treatment.

Abstract: Iron oxide nanocrystals (IONCs) are appealing heat mediator nanoprobes in magnetic-mediated hyperthermia for cancer treatment. Here, specific absorption rate (SAR) values are reported for cube-shaped water-soluble IONCs prepared by a one-pot synthesis approach in a size range between 13 and 40 nm. The SAR values were determined as a function of frequency and magnetic field applied, also spanning technical conditions which are considered biomedically safe for patients. Among the different sizes tested, IONCs with an average diameter of 19 ± 3 nm had significant SAR values in clinical conditions and reached SAR values up to 2452 W/gFe at 520 kHz and 29 kAm–1, which is one of the highest values so far reported for IONCs. In vitro trials carried out on KB cancer cells treated with IONCs of 19 nm have shown efficient hyperthermia performance, with cell mortality of about 50% recorded when an equilibrium temperature of 43 °C was reached after 1 h of treatment.

Duality of Iron Oxide Nanoparticles in Cancer Therapy: Amplification of Heating Efficiency by Magnetic Hyperthermia and Photothermal Bimodal Treatment

Abstract: The pursuit of innovative, multifunctional, more efficient, and safer treatments is a major challenge in preclinical nanoparticle-mediated thermotherapeutic research. Here, we report that iron oxide nanoparticles have the dual capacity to act as both magnetic and photothermal agents. We further explore every key aspect of this magnetophotothermal approach, choosing iron oxide nanocubes for their high efficiency for the magnetic hyperthermia modality itself. In aqueous suspension, the nanocubes' exposure to both: an alternating magnetic field and near-infrared laser irradiation (808 nm), defined as the DUAL-mode, amplifies the heating effect 2- to 5-fold by comparison with magnetic stimulation alone, yielding unprecedented heating powers (specific loss powers) up to 5000 W/g. In cancer cells, the laser excitation restores the optimal efficiency of magnetic hyperthermia, otherwise inhibited by intracellular confinement, resulting in a remarkable heating efficiency in the DUAL-mode (up to 15-fold amplification), with respect to the magnetophotothermal mode. As a consequence, the dual action yielded complete apoptosis-mediated cell death. In solid tumors in vivo, single-mode treatments (magnetic or laser hyperthermia) reduced tumor growth, while DUAL-mode treatment resulted in complete tumor regression, mediated by heat-induced tumoral cell apoptosis and massive denaturation of the collagen fibers, and a long-lasting thermal efficiency over repeated treatments.

Fundamentals and advances in magnetic hyperthermia

Abstract: Nowadays, magnetic hyperthermia constitutes a complementary approach to cancer treatment. The use of magnetic particles as heating mediators, proposed in the 1950s, provides a novel strategy for improving tumor treatment and, consequently, patient's quality of life. This review reports a broad overview about several aspects of magnetic hyperthermia addressing new perspectives and the progress on relevant features such as the ad hoc preparation of magnetic nanoparticles, physical modeling of magnetic heating, methods to determine the heat dissipation power of magnetic colloids including the development of experimental apparatus and the influence of biological matrices on the heating efficiency.