Blood clots in the capillaries are one of the main causes of stroke or heart attack. After thrombosis, a blood clot detaching and moving towards the lungs can cause pulmonary obstruction and ultimately lead to death. Current approaches for preventing the movement and dissolving clots have inherent limitations. This research aimed to eva‎luate two new non-invasive approaches to prevent clot movement and mechanical-chemical abrading of clots by drug-carrying magnetic nanoparticles. In this study, a magnetic immobilizing clot technique was developed. In the presented technique, a clot is immobilizing and dissolving by using magnetic nanoparticles carrying a thrombolytic drug under a magnetic field. The technique of magnetic nano-thrombectomy based on abrading and dissolving of clots by magnetic nanoparticles carrying the drug has also been investigated. With respect to that, zinc ferrite core-shell nanoparticles were synthesized using co-precipitation and stober methods and streptokinase was loaded in it. To analyze the magnetic immobilizing technique of the clot in-vitro conditions, a hydraulic circuit similar to the condition of the ven cava vessel was designed and prototyped to study the effect of significant parameters including magnetic field (0.1, 0.2, and 0.3 Tesla), dose magnetic nanoparticles (0.01, 0.05 and 0.1 mg), fluid pressure (80, 120 and 180 mmHg) and fluid flow rate (2.5, 5 and 7.5 l/min) in different clot sizes. The results show that by increasing the magnetic field strength and the dose of magnetic nanoparticles to their maximum values, 100% of the clots can be immobilized and about 61% of the clot weight can be dissolved. The rate of clot immobilizing and dissolution is directly related to the strength of the magnetic field. While small clots are immobilized by applying a magnetic field of 0.2 T, a stronger magnetic field (0.3 T) is required to immobilized larger clots. In addition, by increasing the magnetic field strength from a minimum of 0.1 to 0.3 T, the dissolution efficiency of large clots increases from 30.9% to 61.4% (P-Value <0.05 is considered in experiments). There is a reverse relationship between clot immobilizing and process parameters including pressure and flow rate. To investigate clot abrading by magnetic nanoparticles carrying a thrombolytic agent, a magnetic nano-thrombectomy device was designed and prototyped. The results of microscopy images, MRI, and high-frequency ultrasound measurements confirm the feasibility of this process. Dynamic light scattering measurements indicate that the size of the debris resulting from the magnetic nano-thrombectomy process is in the nano range (less than 800 nm) that reduces the risk of distal embolism as a concern of current thrombectomy techniques. The results show that the magnetic field of 0.3 T has the greatest effect on the process of magnetic nano-thrombectomy. While increasing the dosage of nanomagnetic particles from 10 to 50 mg/ml increases clot abrading from 42 to 85%, increasing the dosage of nanomagnetic particles to more than 50 mg does not have any effect on abrading the clot. There is also a direct relationship between the rotational frequency of the magnetic field and the amount of clot abrading, so that increasing the frequency of rotation of the magnetic field from 10 to 40 rpm increases the rate of clot abrading from 23 to about 90%. Atomic force microscopic images also do not show any damage to the artificial vessel. The magnetic-clot-immobilizing technique provides a unique technique to prevent clots from moving toward vital organs. In addition, the magnetic-nano-thrombectomy technique has a unique potential in removing other deposits in the arteries.

فخرالدين اشرفي زاده، ژاله ورشوساز

مهشيد خرازيها

مجيد طباخيان،سعيد شيباني،شيدا لباف