Enhanced Detection of Magnetic Nanoparticles Using a Novel Microwave Ferromagnetic Resonance Imaging System

Magnetic DNA Nanomachine for On-Particle Cascade Amplification-Based Ferromagnetic Resonance Detection of Plant MicroRNA

Plant microRNAs play critical roles in post-transcriptional gene regulation of many processes, thus motivating the development of accurate and user-friendly microRNA detection methods for better understanding of, e.g., plant growth, development, and abiotic/biotic stress responses. By integrating the capture probe, fuel strand, primer, and template onto the surface of a magnetic nanoparticle (MNP), we demonstrated a magnetic DNA nanomachine that could conduct an on-particle cascade amplification reaction in response to the presence of target microRNA. The cascade amplification consists of an exonuclease III-assisted target recycling step and a rolling circle amplification step, leading to changes in the MNP arrangement that can be quantified by ferromagnetic resonance spectroscopy. After a careful investigation of the exonuclease III side reaction, the biosensor offers a detection limit of 15 fM with a total assay time of ca. 70 min. Moreover, our magnetic DNA nanomachine is capable of discriminating the target microRNA from its family members. Our biosensor has also been tested on total endogenous microRNAs extracted from Arabidopsis thaliana leaves, with a performance comparable to qRT-PCR.

Microwave Imaging for Early Breast Cancer Detection: Current State, Challenges, and Future Directions

Breast cancer is the most commonly diagnosed cancer type and is the leading cause of cancer-related death among females worldwide. Breast screening and early detection are currently the most successful approaches for the management and treatment of this disease. Several imaging modalities are currently utilized for detecting breast cancer, of which microwave imaging (MWI) is gaining quite a lot of attention as a promising diagnostic tool for early breast cancer detection. MWI is a noninvasive, relatively inexpensive, fast, convenient, and safe screening tool. The purpose of this paper is to provide an up-to-date survey of the principles, developments, and current research status of MWI for breast cancer detection. This paper is structured into two sections; the first is an overview of current MWI techniques used for detecting breast cancer, followed by an explanation of the working principle behind MWI and its various types, namely, microwave tomography and radar-based imaging. In the second section, a review of the initial experiments along with more recent studies on the use of MWI for breast cancer detection is presented. Furthermore, the paper summarizes the challenges facing MWI as a breast cancer detection tool and provides future research directions. On the whole, MWI has proven its potential as a screening tool for breast cancer detection, both as a standalone or complementary technique. However, there are a few challenges that need to be addressed to unlock the full potential of this imaging modality and translate it to clinical settings.

Experimental Characterization of Spurious Signals in Magnetic Nanoparticles Enhanced Microwave Imaging of Cancer

Magnetic nanoparticles enhanced microwave imaging relies on the capability of modulating the response of such nanocomponents at microwaves by means of a (low frequency) polarizing magnetic field. In medical imaging, this capability allows for the detection and imaging of tumors loaded with nanoparticles. As the useful signal is the one which arises from nanoparticles, it is crucial to remove sources of undesired disturbance to enable the diagnosis of early-stage tumors. In particular, spurious signals arise from instrumental drift, as well as from the unavoidable interaction between the polarizing field and the imaging system. In this paper, we experimentally assess and characterize such spurious effects in order to set the optimal working conditions for magnetic nanoparticles enhanced microwave imaging of cancer. To this end, simple test devices, which include all components typically comprised in a microwave imaging system, have been realized and exploited. The experiment’s results allow us to derive design formulas and guidelines useful for limiting the impact of unwanted magnetic effects, as well as that relative to the instrumental drift on the signal generated by the magnetic nanoparticles-loaded tumor.