The biosafety of nanoparticles is gaining extensive attention due to their dichotomous effects in fields of biomedicine and atmospheric chemistry. A number of studies have been carried out focusing on the cytotoxicity of nanoparticles and their interactions with cells. However, the mechanism of nanoparticlecell interactions remains unclear. Here, we review the latest progress in the study of nanoparticle-cell interactions from a cellular chemo-mechanical perspective. Cell mechanics play an important role in cell differentiation, proliferation, apoptosis, polarization, adhesion, and migration. An understanding of the effects of nanoparticles on cell mechanics is therefore needed in order to enhance comprehension of nanoparticle-cell interactions. Firstly, the main molecules and signal pathways related to mechanical chemistry are introduced from three perspectives: cell surface adhesion receptors, the cytoskeleton, and the nucleus. Specifically, integrins and cadherins play a critical role in sensing both the external mechanical force and the force of cell transmission. Actin and microtubules, which are two components of the cytoskeletal network, act as a bridge in mechanical conduction. The nucleus can also be mechanically stressed by the surrounding cytoskeleton through the contraction of the matrix. The nuclear envelope also plays important roles in sensing mechanical signals and in adjusting the morphology and function of the nucleus. We summarize the major nanoparticle-based tools used in the laboratory for the study of cell mechanics, which includes traction force microscopy, atomic force microscopy, optical tweezers, magnetic manipulation, micropillars, and forceinduced remnant magnetization spectroscopy. In addition, we discuss the effects that nanoparticles have on cell mechanics. Nanoparticles interact with the adhesion of molecules on the cell membrane surface and on cell cytoskeletal proteins, which further affects the mechanical properties involved in cell stiffness, cell adhesion, and cell migration. Overall, the general conclusions regarding the effects of nanoparticles on cell mechanics are as follows: (1) Nanoparticles can affect cell adhesion by disrupting tight and adherent junctions, and by regulating cell-extracellular matrix adhesion; (2) Nanoparticles can interact with cytoskeletal proteins (actins and tubulins) leading to structural reorganization or disruption of microtubules and F-actin; (3) Cell stiffness changes with the structural reorganization of the cytoskeleton; (4) Cell migration ability can be affected through changes in the cytoskeleton, cell adhesion, and the expression of cell migrationrelated proteins/molecules. To develop the nano-biosafety evaluation system, future studies should attempt to gain a better understanding of the molecular mechanisms involved with regards to nanoparticles and cell mechanics. Ultimately, further development of new methods and technologies based on nano-mechanical chemistry for diagnosis and treatment purposes are expected, given the wide applicati...

Multiplexed simultaneous detection of various cancer markers is required for accurate diagnosis and treatment of early cancer. In this work, we present a force-coded strategy for the simultaneous detection of tumor-related proteins with tunable dynamic range via magnetic sensing. The multiplexing capability of this method is achieved by designing DNA devices that can recognize different biomarkers and code them with different binding forces measured by the force-induced remnant magnetization spectroscopy, which is not influenced by the color of the light and the solution. Moreover, the force-coded assay with high sensitivity and adjustable detection range is robust, which could be used for practical biological applications such as magnetic sensing, handheld miniaturized systems, and potential in vivo diagnosis.

Biomolecules participate in various physiological and pathological processes through intermolecular interactions generally driven by non-covalent forces. In the present review, the force-induced remnant magnetization spectroscopy (FIRMS) is described and illustrated as a novel method to measure non-covalent forces. During the FIRMS measurement, the molecular magnetic probes are magnetized to produce an overall magnetization signal. The dissociation under the interference of external force yields a decrease in the magnetic signal, which is recorded and collected by atomic magnetometer in a spectrum to study the biological interactions. Furthermore, the recent FIRMS development with various external mechanical forces and magnetic probes is summarized.