Lithographically defined encoded magnetic heterostructures for the targeted screening of kidney cancer.

Renal cell carcinoma (RCC) is the 7th commonest cancer in the UK and the most lethal urological malignancy; 50% of all RCC patients will die from the condition. However, if identified early enough, small RCCs are usually cured by surgery or percutaneous procedures, with 95% 10 year survival. This study describes a newly developed non-invasive urine-based assay for the early detection of RCC. Our approach uses encoded magnetically controllable heterostructures as a substrate for immunoassays. These heterostructures have molecular recognition abilities and embedded patterned codes for a rapid identification of RCC biomarkers. The magnetic heterostructures developed for this study have a magnetic configuration designed for a remote multi axial control of their orientation by external magnetic fields, this control facilitates the code readout when the heterostructures are in liquid. Furthermore, the optical encoding of each set of heterostructures provides a multiplexed analyte capture platform, as different sets of heterostructures, specific to different biomarkers can be mixed together in a patient sample. Our results show a precise magnetic control of the heterostructures with an efficient code readout during liquid immunoassays. The use of functionalised magnetic heterostructures as a substrate for immunoassay is validated for urine specimen spiked with recombinant RCC biomarkers. Initial results of the newly proposed screening method on urine samples from RCC patients, and controls with no renal disorders are presented in this study. Comprehensive optimisation cycles are in progress to validate the robustness of this technology as a novel, non-invasive screening method for RCC.

Early detection of kidney cancer using urinary proteins: a truly non-invasive strategy.

OBJECTIVES: To review urinary protein biomarkers as potential non-invasive, easily obtainable, early diagnostic tools in renal cell carcinoma (RCC). METHODS: A PubMed database search was performed up to the year 2020 to identify primary studies reporting potential urinary protein biomarkers for RCC. Separate searches were conducted to identify studies describing appropriate methods of developing cancer screening programmes and detection of cancer biomarkers. RESULTS: Several urinary protein biomarkers are under validation for RCC diagnostics, e.g. aquaporin-1, perilipin-2, carbonic anhydrase-9, Raf-kinase inhibitory protein, nuclear matrix protein-22, 14-3-3 Protein ß/α and neutrophil gelatinase-associated lipocalin. However, none has yet been validated or approved for clinical use due to low sensitivity or specificity, inconsistencies in appropriate study design, or lack of external validation. CONCLUSIONS: Evaluation of biomarkers' feasibility, sample preparation and storage, biomarker validation, and the application of novel technologies may provide a solution that maximises the potential for a truly non-invasive biomarker in early RCC diagnostics.

Controlling All-Optical Helicity-Dependent Switching in Engineered Rare-Earth Free Synthetic Ferrimagnets.

All-optical helicity-dependent switching in ferromagnetic layers has revealed an unprecedented route to manipulate magnetic configurations by circularly polarized femtosecond laser pulses. In this work, rare-earth free synthetic ferrimagnetic heterostructures made from two antiferromagnetically exchange coupled ferromagnetic layers are studied. Experimental results, supported by numerical simulations, show that the designed structures enable all-optical switching which is controlled, not only by light helicity, but also by the relative Curie temperature of each ferromagnetic layer. Indeed, through the antiferromagnetic exchange coupling, the layer with the larger Curie temperature determines the final orientation of the other layer and so the synthetic ferrimagnet. For similar Curie temperatures, helicity-independent back switching is observed and the final magnetic configuration is solely determined by the initial magnetic state. This demonstration of electrically-detected, optical control of engineered rare-earth free heterostructures opens a novel route toward practical opto-spintronics.

Magnetic particles with perpendicular anisotropy for mechanical cancer cell destruction.

We demonstrate the effectiveness of out-of-plane magnetized magnetic microdiscs for cancer treatment through mechanical cell disruption under an applied rotating magnetic field. The magnetic particles are synthetic antiferromagnets formed from a repeated motif of ultrathin CoFeB/Pt layers. In-vitro studies on glioma cells are used to compare the efficiency of the CoFeB/Pt microdiscs with Py vortex microdiscs. It is found that the CoFeB/Pt microdiscs are able to damage 62 ± 3% of cancer cells compared with 12 ± 2% after applying a 10 kOe rotating field for one minute. The torques applied by each type of particle are measured and are shown to match values predicted by a simple Stoner-Wohlfarth anisotropy model, giving maximum values of 20 fNm for the CoFeB/Pt and 75 fNm for the Py vortex particles. The symmetry of the anisotropy is argued to be more important than the magnitude of the torque in causing effective cell destruction in these experiments. This work shows how future magnetic particles can be successfully designed for applications requiring control of applied torques.

Controlled Payload Release by Magnetic Field Triggered Neural Stem Cell Destruction for Malignant Glioma Treatment.

Stem cells have recently garnered attention as drug and particle carriers to sites of tumors, due to their natural ability to track to the site of interest. Specifically, neural stem cells (NSCs) have demonstrated to be a promising candidate for delivering therapeutics to malignant glioma, a primary brain tumor that is not curable by current treatments, and inevitably fatal. In this article, we demonstrate that NSCs are able to internalize 2 µm magnetic discs (SD), without affecting the health of the cells. The SD can then be remotely triggered in an applied 1 T rotating magnetic field to deliver a payload. Furthermore, we use this NSC-SD delivery system to deliver the SD themselves as a therapeutic agent to mechanically destroy glioma cells. NSCs were incubated with the SD overnight before treatment with a 1T rotating magnetic field to trigger the SD release. The potential timed release effects of the magnetic particles were tested with migration assays, confocal microscopy and immunohistochemistry for apoptosis. After the magnetic field triggered SD release, glioma cells were added and allowed to internalize the particles. Once internalized, another dose of the magnetic field treatment was administered to trigger mechanically induced apoptotic cell death of the glioma cells by the rotating SD. We are able to determine that NSC-SD and magnetic field treatment can achieve over 50% glioma cell death when loaded at 50 SD/cell, making this a promising therapeutic for the treatment of glioma.

Rotating magnetic field induced oscillation of magnetic particles for in vivo mechanical destruction of malignant glioma.

Magnetic particles that can be precisely controlled under a magnetic field and transduce energy from the applied field open the way for innovative cancer treatment. Although these particles represent an area of active development for drug delivery and magnetic hyperthermia, the in vivo anti-tumor effect under a low-frequency magnetic field using magnetic particles has not yet been demonstrated. To-date, induced cancer cell death via the oscillation of nanoparticles under a low-frequency magnetic field has only been observed in vitro. In this report, we demonstrate the successful use of spin-vortex, disk-shaped permalloy magnetic particles in a low-frequency, rotating magnetic field for the in vitro and in vivo destruction of glioma cells. The internalized nanomagnets align themselves to the plane of the rotating magnetic field, creating a strong mechanical force which damages the cancer cell structure inducing programmed cell death. In vivo, the magnetic field treatment successfully reduces brain tumor size and increases the survival rate of mice bearing intracranial glioma xenografts, without adverse side effects. This study demonstrates a novel approach of controlling magnetic particles for treating malignant glioma that should be applicable to treat a wide range of cancers.

Flexible, low-voltage, and low-hysteresis PbSe nanowire field-effect transistors.

We report low-hysteresis, ambipolar bottom gold contact, colloidal PbSe nanowire (NW) field-effect transistors (FETs) by chemically modifying the silicon dioxide (SiO(2)) gate dielectric surface to overcome carrier trapping at the NW-gate dielectric interface. While water bound to silanol groups at the SiO(2) surface are believed to give rise to hysteresis in FETs of a wide range of nanoscale materials, we show that dehydration and silanization are insufficient in reducing PbSe NW FET hysteresis. Encapsulating PbSe NW FETs in cured poly(methyl) methacrylate (PMMA), dehydrates and uniquely passivates the SiO(2) surface, to form low-hysteresis FETs. Annealing predominantly p-type ambipolar PbSe NW FETs switches the FET behavior to predominantly n-type ambipolar, both with and without PMMA passivation. Heating the PbSe NW devices desorbs surface bound oxygen, even present in the atmosphere of an inert glovebox. Upon cooling, overtime oxygen readsorption switches the FET polarity to predominantly p-type ambipolar behavior, but PMMA encapsulation maintains low hysteresis. Unfortunately PMMA is sensitive to most solvents and heat treatments and therefore its application for nanostructured material deposition and doping is limited. Seeking a robust, general platform for low-hysteresis FETs we explored a variety of hydroxyl-free substrate surfaces, including silicon nitride, polyimide, and parylene, which show reduced electron trapping, but still large hysteresis. We identified a robust dielectric stack by assembling octadecylphosphonic acid (ODPA) on aluminum oxide (Al(2)O(3)) to form low-hysteresis FETs. We further integrated the ODPA/Al(2)O(3) gate dielectric stack on flexible substrates to demonstrate low-hysteresis, low-voltage FETs, and the promise of these nanostructured materials in flexible, electronic circuitry.

Ambipolar and unipolar PbSe nanowire field-effect transistors.

Wet-chemical methods, under rigorous air-free conditions, were used to synthesize single-crystalline 10 nm diameter PbSe nanowires (NWs), and electric-field, directed assembly was employed to align NW arrays to form the semiconducting channels of field-effect transistors (FETs). Electrical measurements revealed as-aligned NWs in bottom, gold, contact FETs are predominantly p-type ambipolar, consistent with the presentation of small barriers to electron and hole injection for this low band gap semiconductor. Exposing the NW FET to UV-ozone p-doped the NWs, illustrating the sensitivity of PbSe to oxygen, but controlled oxidation allowed the fabrication of unipolar p-type FETs. Selectively exposing the contact region of as-aligned NW FETs to low to moderate concentrations of hydrazine, commonly used to n-dope nanocrystal and NW devices, switched the predominantly p- to n-type ambipolar behavior as if the entire NW channel was exposed. At these hydrazine concentrations, charge transfer doping the metal-semiconductor interface dominates the FET characteristics. Only upon exposing the NW FETs to high hydrazine concentrations did charge transfer doping of the NW channel overcome the large intrinsic, thermally generated carrier concentration of this low band gap material, modulating the NW carrier concentration and forming unipolar n-type FETs. Pulling low vacuum removed surface hydrazine returning the predominantly p-type ambipolar FET behavior. Doping and dedoping with hydrazine were repeatedly reversible. By applying surface modification to n- and p-dope PbSe NW FETs, we fabricated the first PbSe NW inverters, demonstrating the promise of these nanostructured materials in integrated circuits.