Magnetic Microdevices for MRI-Based Detection of SARS-CoV-2 Viruses.

GOAL: To develop a micron-scale device that can operate as an MRI-based reporter for the presence of SARS-CoV-2 virus. METHODS: Iron rod microdevices were constructed via template-guided synthesis and suspended in phosphate buffered saline (PBS). Heat-inactivated SARS-CoV-2 viruses were added to the samples and imaged with low-field MRI. RESULTS: MRI of microdevices and viruses showed decreased signal intensity at low concentrations of viruses that recovered at higher concentrations. Electron micrographs suggest that reduced MRI intensity may be due to concentration-dependent shielding of water protons from local magnetic inhomogeneities caused by the iron microdevices. CONCLUSIONS: The preliminary results presented in this letter provide justification for further studies exploring the potential diagnostic role of magnetic microdevices in assessing the presence and concentration of SARS-CoV-2 viruses.

Electropermanent magnets for variable-field NMR.

In this work, a dynamically tunable B0 field is used to perform variable-field NMR. The system consists of an array of electropermanent AlNiCo-5 magnets whose magnetizations are individually programmed using pulse-power control. This design allows the field strength to be varied for field-dispersion measurements. An ultra-broadband front-end is utilized that maintains efficient power transmission over a broad range of frequencies for robust operation without probe tuning. We perform T1-T2 correlation measurements at various B0 field strengths (0.5-2 MHz) and demonstrate discrimination of different dairy products. We observe variation in the frequency dependence of the proton spin-lattice relaxation for the different products as a function of the degree of protein hydration. This variable-field technique provides a low-cost alternative to fast field-cycling NMR and could open possibilities for novel contrast measurements and spatial encoding in magnetic resonance imaging.

Magnetically Aligned Nanorods in Alginate Capsules (MANiACs): Soft Matter Tumbling Robots for Manipulation and Drug Delivery.

Soft, untethered microrobots composed of biocompatible materials for completing micromanipulation and drug delivery tasks in lab-on-a-chip and medical scenarios are currently being developed. Alginate holds significant potential in medical microrobotics due to its biocompatibility, biodegradability, and drug encapsulation capabilities. Here, we describe the synthesis of MANiACs-Magnetically Aligned Nanorods in Alginate Capsules-for use as untethered microrobotic surface tumblers, demonstrating magnetically guided lateral tumbling via rotating magnetic fields. MANiAC translation is demonstrated on tissue surfaces as well as inclined slopes. These alginate microrobots are capable of manipulating objects over millimeter-scale distances. Finally, we demonstrate payload release capabilities of MANiACs during translational tumbling motion.

Epirubicin extravasation: consequences of delayed management.

Epirubicin is an anthracycline chemotherapy agent used for treatment of several cancers including oesophageal, breast and gastric. Extravasation is a well-recognised and serious complication of any intravenous therapies but especially chemotherapeutic agents. Signs of the injury can be subtle and without prompt recognition and treatment there can be extensive tissue damage and depending on location of injury this can result in significant functional loss. In this article, a case of delayed management of epirubicin extravasation from a cannula situated at the dorsum of the hand is discussed. Successful surgical reconstruction of the resulting substantial tissue damage using a radial forearm flap 21 days following injury is described.