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Regulation of genetic activity in single cells and tissues is pivotal to determine key cellular functions in current biomedicine, yet the conventional biochemical activators lack spatiotemporal precision due to the diffusion-mediated slow kinetics and nonselectivity. Here, we describe a magnetogenetic method for target-specific activation of a clustered regularly interspaced short palindromic repeats (CRISPR) system for the regulation of intracellular proteins. We used magnetomechanical force generated by the magnetic nanostructure to activate pre-encoded Piezo1, the mechanosensitive ion channel, on the target cell. The activated Piezo1 further triggers the intracellular Ca

Nanoparticles with multifunctionality and high colloidal stability are essential for biomedical applications. However, their use is often hindered by the formation of thick coating shells and/or nanoparticle agglomeration. Herein, we report a single nanoparticle coating strategy to form 1 nm polymeric shells with a variety of chemical functional groups and surface charges. Under exposure to alternating magnetic field, nanosecond thermal energy pulses trigger a polymerization in the region only a few nanometers from the magnetic nanoparticle (MNP) surface. Modular coatings containing functional groups, according to the respective choice of monomers, are possible. In addition, the surface charge can be tuned from negative through neutral to positive. We adopted a coating method for use in biomedical targeting studies where obtaining compact nanoparticles with the desired surface charge is critical. A single MNP with a zwitterionic charge can provide excellent colloidal stability and cell-specific targeting.

The current gold standard for COVID-19 confirmation is RT-PCR, which possesses high sensitivity and specificity, but a long turnaround time has been a drawback. Here, we introduce a nanoPCR platform that can yield breakthroughs in RT-PCR speed and decentralize the diagnostic testing. A key innovation is to exploit magneto-plasmonic nanoparticles for dual purposes: fast thermocycling through plasmonic heating and enhanced signal detection via magnetic fluorescence switch. We further integrated these functionalities into a portable system to streamline point-of-care (POC) COVID-19 diagnostics with a “one-step-finish” approach from sampling to result. When applied with clinical COVID-19 samples, nanoPCR achieved an analytical performance of sensitivity and specificity comparable to that of a benchtop instrument but completed the entire detection within 18 minutes (vs. 2.5 hours for regular RT-PCR), which makes it ideal for rapid POC diagnostics. This platform technology is readily scalable for higher throughput and expandable to other disease targets, promising broader impacts in on-site molecular testing.

While neural cell transplantation represents a promising therapy for neurodegenerative diseases, the formation of functional networks of transplanted cells with host neurons constitutes one of the challenging steps. Here, we introduce a magnetic guidance methodology that controls neurite growth signaling via magnetic nanoparticles (MNPs) conjugated with antibodies targeting the deleted in colorectal cancer (DCC) receptor (DCC-MNPs). Activation of the DCC receptors by clusterization and subsequent axonal growth of the induced neuronal (iN) cells was performed in a spatially controlled manner. In addition to the directionality of the magnetically controlled axon projection, axonal growth of the iN cells assisted the formation of functional connections with pre-existing primary neurons. Our results suggest magnetic guidance as a strategy for improving neuronal connectivity by spatially guiding the axonal projections of transplanted neural cells for synaptic interactions with the host tissue.

Multifunctional magnetic nanoparticles have shown great promise as next-generation imaging and perturbation probes for deciphering molecular and cellular processes. As a consequence of multicomponent integration into a single nanosystem, pre-existing nanoprobes are typically large and show limited access to biological targets present in a crowded microenvironment. Here, we apply organic-phase surface PEGylation, click chemistry, and charge-based valency discrimination principles to develop compact, modular, and monovalent magnetofluorescent nanoparticles (MFNs). We show that MFNs exhibit highly efficient labeling to target receptors present in cells with a dense and thick glycocalyx layer. We use these MFNs to interrogate the E-cadherin-mediated adherens junction formation and F-actin polymerization in a three-dimensional space, demonstrating the utility as modular and versatile mechanogenetic probes in the most demanding single-cell perturbation applications.

Tools capable of imaging and perturbing mechanical signaling pathways with fine spatiotemporal resolution have been elusive, despite their importance in diverse cellular processes. The challenge in developing a mechanogenetic toolkit (i.e., selective and quantitative activation of genetically encoded mechanoreceptors) stems from the fact that many mechanically activated processes are localized in space and time yet additionally require mechanical loading to become activated. To address this challenge, we synthesized magnetoplasmonic nanoparticles that can image, localize, and mechanically load targeted proteins with high spatiotemporal resolution. We demonstrate their utility by investigating the cell-surface activation of two mechanoreceptors: Notch and E-cadherin. By measuring cellular responses to a spectrum of spatial, chemical, temporal, and mechanical inputs at the single-molecule and single-cell levels, we reveal how spatial segregation and mechanical force cooperate to direct receptor activation dynamics. This generalizable technique can be used to control and understand diverse mechanosensitive processes in cell signaling. VIDEO ABSTRACT.