Feature Matching of Microsecond-Pulsed Magnetic Fields Combined with Fe3O4 Particles for Killing A375 Melanoma Cells.

The combination of magnetic fields and magnetic nanoparticles (MNPs) to kill cancer cells by magneto-mechanical force represents a novel therapy, offering advantages such as non-invasiveness, among others. Pulsed magnetic fields (PMFs) hold promise for application in this therapy due to advantages such as easily adjustable parameters; however, they suffer from the drawback of narrow pulse width. In order to fully exploit the potential of PMFs and MNPs in this therapy, while maximizing therapeutic efficacy within the constraints of the narrow pulse width, a feature-matching theory is proposed, encompassing the matching of three aspects: (1) MNP volume and critical volume of Brownian relaxation, (2) relaxation time and pulse width, and (3) MNP shape and the intermittence of PMF. In the theory, a microsecond-PMF generator was developed, and four kinds of MNPs were selected for in vitro cell experiments. The results demonstrate that the killing rate of the experimental group meeting the requirements of the theory is at least 18% higher than the control group. This validates the accuracy of our theory and provides valuable guidance for the further application of PMFs in this therapy.

The effect of ultrasonic power on the physicochemical properties and antioxidant activities of frosted figs pectin.

Ultrasound has been widely used in industry due to its high energy and efficiency. This study optimized the ultrasonic-assisted extraction (UAE) process of frosted figs pectin (FFP) using response surface methodology (RSM), and further investigated the effect of ultrasonic power on the structural characteristics and antioxidant activities of FFPs. The UAE method of FFP through RSM was optimized, and the optimal extraction process conditions, particle size of 100 mesh, pH value of 1.95, liquid-solid ratio of 47:1 (mL/g), extraction temperature of 50 °C and extraction time of 65 min, were obtained. The extraction rate of FFP under this condition was 37.97 ± 2.56 %. Then, the four FFPs modified by ultrasound were obtained by changing the ultrasonic power. Research had found that ultrasonic power had little effect on the monosaccharide composition, Zeta potential, as well as the thermal stability and appearance structure of the four FFPs. However, ultrasonic power had a significant impact on other properties of FFP: as the ultrasonic power increased, the DM% and particle size decreased continuously, while the total carbohydrate content increased. Meanwhile, ultrasonic power also had a significant impact on antioxidant activities of FFPs. From the research results, it could be seen that different ultrasonic power had certain changes in its spatial structure and properties, and the structural changes also affected the biological activity of FFP. The study of the effects of ultrasonic power on the physicochemical properties and biological activity of FFP lays the foundation for the development and application of FFP in food additives and natural drug carriers.