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All van der Waals Fe 3 GeTe 2 /Cr 2 Ge 2 Te 6 /graphite magnetic heterojunctions have been fabricated via mechanical exfoliation and stacking, and their magnetotransport properties are studied in detail. At low bias voltages, large negative junction magnetoresistances have been observed and are attributed to spin-conserving tunneling transport across an insulating Cr 2 Ge 2 Te 6 layer. With increasing bias, a crossover to Fowler–Nordheim tunneling takes place. The negative sign of the tunneling magnetoresistance suggests that the bottom of a conduction band in Cr 2 Ge 2 Te 6 belongs to minority spins, opposite to the findings of some first-principles calculations. This work shows that the vdW heterostructures based on 2D magnetic insulators are a valuable platform to gain further insight into spin polarized tunneling transport, which is the basis for pursuing high performance spintronic devices and a large variety of quantum phenomena. 

Abstract Digital protein assays have great potential to advance immunodiagnostics because of their single-molecule sensitivity, high precision, and robust measurements. However, translating digital protein assays to acute clinical care has been challenging because it requires deployment of these assays with a rapid turnaround. Herein, we present a technology platform for ultrafast digital protein biomarker detection by using single-molecule counting of immune-complex formation events at an early, pre-equilibrium state. This method, which we term “pre-equilibrium digital enzyme-linked immunosorbent assay” (PEdELISA), can quantify a multiplexed panel of protein biomarkers in 10 µL of serum within an unprecedented assay incubation time of 15 to 300 seconds over a 104 dynamic range. PEdELISA allowed us to perform rapid monitoring of protein biomarkers in patients manifesting post-chimeric antigen receptor T-cell therapy cytokine release syndrome, with ∼30-minute sample-to-answer time and a sub–picograms per mL limit of detection. The rapid, sensitive, and low-input volume biomarker quantification enabled by PEdELISA is broadly applicable to timely monitoring of acute disease, potentially enabling more personalized treatment.