ability of RNA moieties to serve both as a genetic source code and as a catalytic repertoire suggests them as excellent drug targets, beyond their use as a behavioral blueprint for regulatory protein production. Despite their role, single RNA has limited practical applications due to its intrinsic thermodynamic and chemical instability, the small scale of production facilities, lack of available toolkits, difficulty in structure and stability predictions. [8][9][10][11][12][13] To resolve the shortcomings of single RNA nanomaterials, few attempts have been made to develop macroscopic RNA moieties to identify them as functional mimics with a wide range of applications such as delivery vehicles for cancer therapy and cell signal sensing. [14][15][16][17] Several polymeric-nucleic acid hybrids have been discovered but they cannot overcome the additional conjugation steps or postfunctionalization methods resulting in decreased efficiency and lower cost effectiveness. [18] Here, we demonstrate a simple and integrated RNA hydrogel made of structurally long RNA that can articulate function without extraneous support. DNA templates programmed with the G-quadruplex structural and purposeful motif were used to form a function-encoding, free-standing RNA hydrogel. Multivalent electrostatic interactions of the G-quadruplexes (G4) in RNA can self-fold into complex structures that can serve as major biological regulators in protein synthesis and in catalysis. Due to the abundance of structural primitives and functional diversity, RNA has been utilized for designing nature-defined goals despite its intrinsic chemical instability and lack of technologies. Here, a robust, free-standing RNA hydrogel is developed through a sequential process involving both ligation and rolling circle transcription to form RNA G-quadruplexes, capable of both catalytic activity and enhancing expression of several proteins in sub-compartmentalized, phase-separated translation environments. The observations suggest that this hydrogel will expand RNA research and impact practical RNA principles and applications.

Invadopodia are involved in cancer invasion by generating mechanical forces and secreting proteolytic enzymes. It is hypothesized that physical forces applied to integrin, especially α 5 β 1 integrin, are strongly associated with the generation of invadopodial forces and protrusive activity of invadopodia; however, their mechanical relationship remains elusive. Here, a new deoxyribonucleic acid-based force probe is developed for mapping α 5 β 1 integrin tension with single-molecule precision. Using this probe, the formation and maturation of invadopodia depending on integrin type and tension are investigated. In addition, the spatio-temporal analysis of the integrin tension map is performed to measure changes in integrin tension and invadopodial force in each stage of invadopodia development. Consequently, it is found that α 5 β 1 integrin tension above 40 pN is critical not only for adhesion but also for the maturation of invadopodia, eventually leading to the generation of a strong invadopodial force greater than 100 pN through α 5 β 1 integrinligand complexes with actomyosin contractility. This biophysical mechanism underlying the invadopodia formation and mechanical activation may provide new insights into cancer invasion and metastasis.

Physical interactions between cells and micro/nanometer-sized architecture presented in an extracellular matrix (ECM) environment significantly influence cell adhesion and morphology, often facilitating the incidence of diseases, such as cancer invasion and metastasis. Sensing and responding to the topographical cues are deeply associated with a physical interplay between integrins, ligands, and mechanical force transmission, ultimately determining diverse cell behavior. Thus, how the tension applied to the integrin-ligand bonds controls cells’ response to the topographical cues needs to be elucidated through quantitative analysis. Here, in this brief research report, we reported a novel platform, termed “topo-tension gauge tether (TGT),” to visualize single-molecule force applied to the integrin-ligand on the aligned anisotropic nanopatterns. Using the topo-TGT assay, first, topography-induced adhesion and morphology of cancerous and normal cells were compared with the pre-defined peak integrin tension. Next, spatial integrin tensions underneath cells were identified using reconstructed integrin tension maps. As a result, we characterized each cell’s capability to comply with nanotopographies and the magnitude of the spatial integrin tension. Altogether, the quantitative information on integrin tension will be a valuable basis for understanding the biophysical mechanisms underlying the force balance influencing adhesion to the topographical cues.

A major difference between amyloid precursor protein (APP) isoforms (APP695 and APP751) is the existence of a Kunitz type protease inhibitor (KPI) domain which has a significant impact on the homo‐ and hetero‐dimerization of APP isoforms. However, the exact molecular mechanisms of dimer formation remain elusive. To characterize the role of the KPI domain in APP dimerization, we performed a single molecule pull down (SiMPull) assay where homo‐dimerization between tethered APP molecules and soluble APP molecules was highly preferred regardless of the type of APP isoforms, while hetero‐dimerization between tethered APP751 molecules and soluble APP695 molecules was limited. We further investigated the domain level APP‐APP interactions using coarse‐grained models with the Martini force field. Though the model initial ternary complexes (KPI‐E1, KPI‐KPI, KPI‐E2, E1‐E1, E2‐E2, and E1‐E2) generated using HADDOCK (HD) and AlphaFold2 (AF2), the binding free energy profiles and the binding affinities of the domain combinations were investigated via the umbrella sampling with Martini force field. Additionally, membrane‐bound microenvironments at the domain level were modeled. As a result, it was revealed that the KPI domain has a stronger attractive interaction with itself than the E1 and E2 domains, as reported elsewhere. Thus, the KPI domain of APP751 may form additional attractive interactions with E1, E2 and the KPI domain itself, whereas it is absent in APP695. In conclusion, we found that the APP751 homo‐dimer formation is predominant than the homodimerization in APP695, which is facilitated by the presence of the KPI domain.

The emergence of fatal viruses that pose continuous threats to global health has fueled the intense effort to develop direct, accurate, and high-throughput virus detection platforms. Current diagnostic methods, including qPCR and rapid antigen tests, indicate how much of the virus is present, whether small fragments or whole viruses. However, these methods do not indicate the probability of the virus to be active, capable of interacting with host cells and initiating the infection cycle. Herein, a sialic acid-presenting fusogenic liposome (sLipo-Chol) nanosensor with purposefully modulated membrane rigidity to rapidly detect the fusion-competent influenza A virus (IAV) is developed. This nanosensor possesses virus-specific features, including hemagglutinin (HA) binding and HA-mediated membrane fusion. It is explored how the fusogenic capability of sLipo-Chol with different membrane rigidities impacts their sensing performance by integrating Förster resonance energy transfer (FRET) pairs into the bilayers. The addition of an intact virus led to instant FRET signal changes, thus enabling the direct detection of diverse IAV subtypes-even in avian fecal samples-within an hour at room temperature. Therefore, the sensing approach, with an understanding of the cellular pathogenesis of influenza viruses, will aid in developing bioinspired nanomaterials for evolution into nanosystems to detect infection-competent viruses.