فصلنامه دنیای نانو
پیاپی 70 (بهار 1402)

Brain cancer is one of the most important cancers with needing to find non-invasive local methods for its treatment. Increasing the local temperature of the tumor area by the interaction of laser light and nanoparticles can be considered as a suitable solution for cancer treatment. In the paper, the effect of 793 nm continuous diode laser irradiation with a power of 1W and gaussian laser-beam profiles on the treatment of brain tumor with a diameter and thickness of 10 and 3 mm respectively is numerically investigated by the finite element method (FEM). The brain tumor is accumulated with gold nanorods. The results indicate that the exposure laser time has a significant effect on the temperature, the fraction of necrotic tissue in different positions of the tumor and healthy tissue, and therefore on the success of the treatment, which is due to the effect of the laser radiation time on the received heat dose by the cancer cells in different areas. The results show that the temperature and fraction of necrotic tissue are different in different positions due to the light absorption in the direction of propagation and also the distribution (Gaussian) of the laser beam profile. Also, selective treatment of brain cancer is possible with photothermal laser treatment using a diode laser and gold nanorods.

Chitosan is derived from non-toxic renewable resources and acts as a compatible and effective biomaterial. As an anti-cancer drug, quercetin has low solubility. Chitosan-based nanocarriers are of particular interest because they can enhance the bioavailability and anticancer efficacy of quercetin by passively or actively targeting cancer tissues. On the other hand, the active centers in the main structure of chitosan enable the creation of nanocarriers with various cross-links on the surface. Thus, this leads to targeted release in the patient's body and avoids damage to healthy tissue. On the other hand, chitosan is a pH-sensitive biopolymer, which changes the hydrophilic and hydrophobic balance in the polymer network according to pH conditions and reacts to the acidic environment around cancer cells to collapse the structure. As a result, it causes the controlled release of quercetin in cancerous tumors and reduces its harmful effects on normal cells. This study investigated the effectiveness of chitosan-based nanocarriers in improving and promoting the release of the anti-cancer drug quercetin.

In this study, the performance of fullerene (C20) as an adsorbent and sensor for the removal and detection of cefalexin was scrutinized by density functional theory computations. The negative values of adsorption energies showed cefalexin interaction with the nanostructure is experimentally possible. The negative values of enthalpy changes and Gibbs free energy variations demonstrated cefalexin adsorption on the surfaces of the adsorbent is exothermic and spontaneous. The values of thermodynamic constants indicated cefalexin interaction with C20 is reversible, equilibrium and two-sided. The NBO results showed cefalexin adsorption on the pristine fullerene is a physisorption because of non-formation of chemical bonds. The influence of temperature on the adsorption process was inspected and the obtained results showed cefalexin interaction with the nanostructure is more favorable at lower temperatures. The computed DOS spectrums showed the bandgap of C20 experienced a +296.9% decline from 1.950 (eV) to 7.750 (eV). Hence, this nanostructure can be employed as a sensing material for the development of new electrochemical sensors for the detection of cefalexin.

Nanofluids, which are obtained from the distribution of nano-sized particles in normal fluids, are a new generation of fluids with great potential in industrial applications. The size of the particles used in nanofluids ranges from 1 nm to 100 nm. Viscosity is one of the important characteristics of nanofluids, which has a very important effect on heat transfer. In this research, the parameters affecting the viscosity of nanofluids were investigated. Different theoretical models can be used to estimate the viscosity of nanofluids. But the experimental results show that the viscosity of the nanofluid does not correspond well with the theoretical models. This difference is due to the effect of Brownian motion, the assumptions made when deriving the models, the mathematical modeling approach and the scattering techniques. In reality, the viscosity of nanofluid depends on many parameters such as base fluids, particle volume fraction, particle size, particle shape, temperature, shear rate, pH value, surfactants, dispersion techniques, particle size distribution and particle aggregation.

Auger electrons (AEs) are emitted by radionuclides such as , , , that decay by electron capture or internal conversion . These low energy electrons deposit their energy over nanometer-micrometer distance which results in high linear energy transfer that leads to lethal damage in cancer cells. Therefore, radiotherapeutics including the AE-emitting radionuclides have great potential for cancer treatment. The highest energy deposition occurs in , and the diameter of double-strand DNA is about , hence, when AEs are released in the vicinity of the cell nucleus, they can cause lethal double DNA strand breaks. Targeted radionuclide therapy in which radionuclides are carried by nanostructures can be very successful in cancer treatment. Transportation of important radionuclides using organic and inorganic nanostructures has an important role in development of radiotherapeutics and radionuclide therapy. The high surface area to volume ratio of nanoparticles makes them suitable for adding polymers or biologically active molecules including therapeutic or diagnostic elements which have high affinity to the receptors on tumor cells. Therefore, simultaneous imaging and radiotherapeutic is possible. In addition, using high-Z nanoparticles increases the emission of photoelectrons and Auger electrons resulting the more effectiveness of the treatment. Therefore, nanostructure materials and design are very important. In this paper, we discuss the properties of Auger electron and the the transportation of Auger electron emitters by nanostructures in cancer therapy.

Liquid biofuels have been selected by users due to their availability, higher calorific value, safety for usage, easy adaptability with fewer technological changes and even political issues. Considering the operational challenges faced by biofuel production, green energies have a limited share of the global primary energy supply. Newly-emerged nanoprocessing approaches are exploited to enhance bioenergy production efficiency. The potential of nano-particles and nano-additives supplementation in biodiesel has been introduced during the present study. Implementation of nano-additives could lead to more power output, less fuel consumption as well as fewer emissions, higher thermal efficiency, decreased cost of operation and enhanced reliability and durability for diesel engines. Poor physicochemical properties of biodiesel at low temperatures, higher fuel consumption and lower energy content could be disappeared using nanotechnology. Most of the practical works to mask the shortcomings of biodiesel have focused on fuel modification methods through further blending and feedstock screening and engineering of the oily feedstock; The application of fuel nano-additives brings meaningful improvement in the thermophysical and chemical properties of the biodiesel.