Virus detection methods based on the nonlinear magnetic response of magnetic nanoparticles have been investigated, and magnetic detection methods using the third harmonic have been widely applied on account of their high sensitivity, short measurement-time, and low cost. In this letter, we propose a virus detection method using the second harmonics to improve the signal intensity. We find that the signal to noise ratio of the second harmonic is approximately three times higher than that of the third harmonic. A comparison of the ratio of the second harmonic to the fourth harmonic (R 24 ) and the ratio of the third harmonic to the fifth harmonic (R 35 ) shows that R 24 is more sensitive to identifying changes in virus concentration. Our proposed method has the potential to be utilized for rapid screening on virus detection.
Virus detection methods based on nonlinear magnetic response of magnetic nanoparticles have been investigated, and magnetic detection methods using the third harmonic are widely applied, owing to their high sensitivity and short measurement time. This paper proposes a virus detection method based on the second harmonic because of its larger signal component. We found that the second harmonic signal is superior to the third harmonic signal for small nanobeads and a large change of the second harmonic signal in the signal-to-noise ratio (SNR) with nanobeads concentration. In addition, a virus detection limit of 100 pg/ml is achieved. Therefore, the proposed method can potentially be utilized for rapid screening of viruses.
Magnetic hyperthermia with magnetic nanoparticles (MNPs) has been introduced to selective treatment of tumor and the MNPs also has demonstrated diagnosis. For non-invasive treatment, a therapeutic platform with temperature monitoring that can avoid overheating in normal tissues is of vital importance. In this study, we have developed a wireless temperature monitoring system by utilizing the combination of magnetic harmonic signals of the MNPs for magnetic hyperthermia treatment in laboratory experiments. We achieved an accurate measurement with an error of 0.18 °C. For practical use on breast/oral cancer, a detectable distance of at least 10 mm is required. To demonstrate the feasibility toward future biomedical applications, we investigated the dependency on the amount of Resovist® and the error is less than 0.5 °C in a 10 mm distance. Our system can measure the correct temperature regardless of Resovist amount. The results indicate that our system can apply for monitoring temperature on magnetic hyperthermia treatment.
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