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Communications Biology May 2024Neurons grow neurites of several tens of micrometers in length, necessitating active transport from the cell body by motor proteins. By tracking fluorophores as...
Neurons grow neurites of several tens of micrometers in length, necessitating active transport from the cell body by motor proteins. By tracking fluorophores as minimally invasive labels, MINFLUX is able to quantify the motion of those proteins with nanometer/millisecond resolution. Here we study the substeps of a truncated kinesin-1 mutant in primary rat hippocampal neurons, which have so far been mainly observed on polymerized microtubules deposited onto glass coverslips. A gentle fixation protocol largely maintains the structure and surface modifications of the microtubules in the cell. By analyzing the time between the substeps, we identify the ATP-binding state of kinesin-1 and observe the associated rotation of the kinesin-1 head in neurites. We also observed kinesin-1 switching microtubules mid-walk, highlighting the potential of MINFLUX to study the details of active cellular transport.
Topics: Kinesins; Animals; Rats; Neurites; Microtubules; Hippocampus; Cells, Cultured
PubMed: 38811803
DOI: 10.1038/s42003-024-06358-4 -
Nature Jun 2024Composites from 2D nanomaterials show uniquely high electrical, thermal and mechanical properties. Pairing their robustness with polarization rotation is needed for...
Composites from 2D nanomaterials show uniquely high electrical, thermal and mechanical properties. Pairing their robustness with polarization rotation is needed for hyperspectral optics in extreme conditions. However, the rigid nanoplatelets have randomized achiral shapes, which scramble the circular polarization of photons with comparable wavelengths. Here we show that multilayer nanocomposites from 2D nanomaterials with complex textured surfaces strongly and controllably rotate light polarization, despite being nano-achiral and partially disordered. The intense circular dichroism (CD) in nanocomposite films originates from the diagonal patterns of wrinkles, grooves or ridges, leading to an angular offset between axes of linear birefringence (LB) and linear dichroism (LD). Stratification of the layer-by-layer (LBL) assembled nanocomposites affords precise engineering of the polarization-active materials from imprecise nanoplatelets with an optical asymmetry g-factor of 1.0, exceeding those of typical nanomaterials by about 500 times. High thermal resilience of the composite optics enables operating temperature as high as 250 °C and imaging of hot emitters in the near-infrared (NIR) part of the spectrum. Combining LBL engineered nanocomposites with achiral dyes results in anisotropic factors for circularly polarized emission approaching the theoretical limit. The generality of the observed phenomena is demonstrated by nanocomposite polarizers from molybdenum sulfide (MoS), MXene and graphene oxide (GO) and by two manufacturing methods. A large family of LBL optical nanocomponents can be computationally designed and additively engineered for ruggedized optics.
PubMed: 38811736
DOI: 10.1038/s41586-024-07455-4 -
MethodsX Jun 2024Electroencephalogram (EEG) electrode digitization is crucial for accurate EEG source estimation, and several commercial systems are available for this purpose. The...
Electroencephalogram (EEG) electrode digitization is crucial for accurate EEG source estimation, and several commercial systems are available for this purpose. The present study aimed to evaluate the digitizing accuracy of electromagnetic and optical systems. Additionally, we introduced a novel rotation method for the electromagnetic system and compared its accuracy with the conventional method of electromagnetic and optical systems. In the conventional method, the operator moves around a stationary participant to digitize, while the participant does not move their head or body. In contrast, in our proposed rotation method with an electromagnetic system, the operator rotates the participant sitting on a swivel chair to digitize in a consistent position. We showed high localization accuracy in both the optical and electromagnetic systems, with an average localization error of less than 3.6 mm. Comparisons of the digitization methods revealed that the electromagnetic system demonstrates superior digitizing accuracy compared to the optical system. Notably, the proposed rotational method is the most accurate among the three methods, which can be attributed to the consistent positioning of EEG electrode digitization within the electromagnetic field. Considering the affordability of the electromagnetic system, our findings provide valuable insights for researchers aiming for precise EEG source estimation.•The study compares the accuracy of electromagnetic and optical systems for EEG electrode digitization, introducing a novel rotation method for improved consistency and precision.•The electromagnetic system, especially with the proposed rotation method, achieves superior digitizing accuracy over the optical system.•Highlighting the cost-effectiveness and precision of the electromagnetic system with the rotation method, this research offers significant insights for achieving precise EEG source estimation.
PubMed: 38808097
DOI: 10.1016/j.mex.2024.102766 -
ACS Sensors Jun 2024Cardiac hypertrophy characterized by abnormal cardiomyocyte viscosity is a typical sign of heart failure (HF) with vital importance for early diagnosis. However, current...
Cardiac hypertrophy characterized by abnormal cardiomyocyte viscosity is a typical sign of heart failure (HF) with vital importance for early diagnosis. However, current biochemical and imaging diagnostic methods are unable to detect this subclinical manifestation. In this work, we developed a series of NIR-I fluorescence probes for detecting myocardial viscosity based on the pyridazinone scaffold. The probes showed weak fluorescence due to free intramolecular rotation under low-viscosity conditions, while they displayed strong fluorescence with limited intramolecular rotation in response to a high-viscosity environment. Among them, exhibited higher stability and photobleaching resistance than commercial dyes. Its specific response to viscosity was not influenced by the pH and biological species. Furthermore, showed rapid and accurate responses to the viscosity of isoproterenol (ISO)-treated H9C2 cardiomyocytes with good biocompatibility. More importantly, demonstrated excellent sensitivity in monitoring myocardial viscosity variation in HF mice in vivo, potentially enabling earlier noninvasive identification of myocardial abnormalities compared to traditional clinical imaging and biomarkers. These findings revealed that can serve as a powerful tool to monitor myocardial viscosity, providing the potential to advance insights into a pathophysiological mechanism and offering a new reference strategy for early visual diagnosis of HF.
Topics: Fluorescent Dyes; Heart Failure; Animals; Mice; Viscosity; Myocytes, Cardiac; Early Diagnosis; Rats; Cell Line; Isoproterenol; Humans; Optical Imaging; Infrared Rays; Male
PubMed: 38807573
DOI: 10.1021/acssensors.4c00258 -
Macromolecular Rapid Communications May 2024Molecular motor amphiphiles have already been widely attempted for dynamic nanosystems across multiple length-scale for developments of small functional materials,...
Molecular motor amphiphiles have already been widely attempted for dynamic nanosystems across multiple length-scale for developments of small functional materials, including controlling macroscopic foam properties, amplifying motion as artificial molecular muscles, and serving as extracellular matrix mimicking cell scaffolds. However, limiting examples of bola-type molecular motor amphiphiles are considered for constructing macroscopic biomaterials. Herein, this work presents the designed two second generation molecular motor amphiphiles, motor bola-amphiphiles (MBAs). Aside from the photoinduced motor rotation of MBAs achieved in both organic and aqueous media, the rate of recovering thermal helix inversion step can be controlled by the rotor part with different steric hindrances. Dynamic assembled structures of MBAs are observed under (cryo)-transmission electron microscopy (TEM). This dynamicity assists MBAs in further assembling as macroscopic soft scaffolds by applying a shear-flow method. Upon photoirradiation, the phototropic bending function of MBA scaffolds is observed, demonstrating the amplification of molecular motion into macroscopic phototropic bending functions at the macroscopic length-scale. Since MBAs are confirmed with low cytotoxicity, human bone marrow-derived mesenchymal stem cells (hBM-MSCs) can grow on the surface of MBA scaffolds. These results clearly demonstrate the concept of designing MBAs for developing photoresponsive dynamic functional materials to create new-generation soft robotic systems and cell-material interfaces.
PubMed: 38805189
DOI: 10.1002/marc.202400261 -
Physical Review Letters May 2024We demonstrate the emergence of nonreciprocal superradiant phase transitions and novel multicriticality in a cavity quantum electrodynamics system, where a two-level...
We demonstrate the emergence of nonreciprocal superradiant phase transitions and novel multicriticality in a cavity quantum electrodynamics system, where a two-level atom interacts with two counterpropagating modes of a whispering-gallery-mode microcavity. The cavity rotates at a certain angular velocity and is directionally squeezed by a unidirectional parametric pumping χ^{(2)} nonlinearity. The combination of cavity rotation and directional squeezing leads to nonreciprocal first- and second-order superradiant phase transitions. These transitions do not require ultrastrong atom-field couplings and can be easily controlled by the external pump field. Through a full quantum description of the system Hamiltonian, we identify two types of multicritical points in the phase diagram, both of which exhibit controllable nonreciprocity. These results open a new door for all-optical manipulation of superradiant transitions and multicritical behaviors in light-matter systems, with potential applications in engineering various integrated nonreciprocal quantum devices.
PubMed: 38804940
DOI: 10.1103/PhysRevLett.132.193602 -
Physical Review Letters May 2024We present the operating principle and the first observing run of a novel kind of direct detector for axions and axionlike particles in the galactic halo. Sensitive to...
We present the operating principle and the first observing run of a novel kind of direct detector for axions and axionlike particles in the galactic halo. Sensitive to the polarisation rotation of linearly polarised laser light induced by an axion field, our experiment is the first detector of its kind collecting scientific data. We discuss our peak sensitivity of 1.51×10^{-10} GeV^{-1} (95% confidence level) to the axion-photon coupling strength in the axion mass range of 1.97-2.01 neV which is, for instance, motivated by supersymmetric grand-unified theories. We also report on effects that arise in our high-finesse in-vacuum cavity at an unprecedented optical continuous-wave intensity of 4.7 MW/cm^{2}. Our detector already belongs to the most sensitive direct searches within its measurement band, and our results pave the way towards surpassing the current sensitivity limits even of astrophysical observations in the mass range from 10^{-8} down to 10^{-16} eV via quantum-enhanced laser interferometry, especially with the potential of scaling our detector up to kilometer length.
PubMed: 38804919
DOI: 10.1103/PhysRevLett.132.191002 -
Analytical Methods : Advancing Methods... Jun 2024Fluorescent labeling is a widely used method for protein detection and fluorescence imaging. A solvatochromic and fluorogenic molecular rotor DASPBCl was developed for...
Fluorescent labeling is a widely used method for protein detection and fluorescence imaging. A solvatochromic and fluorogenic molecular rotor DASPBCl was developed for covalent protein labeling in solution and SDS-PAGE, and also for stable mitochondria labeling and fluorescence imaging. The dye DASPBCl consisted of a 4-(,-dimethylamino)phenyl moiety as the electron donor and a positively charged -benzylpyridinium moiety as the electron acceptor. A benzyl chloride group was introduced into the pyridine moiety for covalent labeling of thiol in proteins. When the fluorescent dye DASPBCl is covalently labeled to the thiol of proteins, significantly enhanced fluorescence was obtained, which is attributed to the polarity sensitivity caused solvatochromic effect from the hydrophobic protein structure and the viscosity sensitivity caused fluorogenic effect from the restriction of single bond rotation. DASPBCl exhibits high sensitivity and good linear response for protein detection in SDS-PAGE analysis with both the pre-staining method and post-staining method. DASPBCl was also successfully used for covalently protein-anchored fluorescence imaging of mitochondria in living cells.
Topics: Fluorescent Dyes; Mitochondria; Humans; Electrophoresis, Polyacrylamide Gel; Sulfhydryl Compounds; Optical Imaging; HeLa Cells; Staining and Labeling; Proteins
PubMed: 38804857
DOI: 10.1039/d4ay00376d -
Phytochemistry Aug 2024Fungi from the genus Aspergillus are important resources for the discovery of bioactive agents. This investigation characterized the isolation, structural elucidation,...
Fungi from the genus Aspergillus are important resources for the discovery of bioactive agents. This investigation characterized the isolation, structural elucidation, and antimicrobial evaluation of 46 metabolites produced by the marine-derived fungus Aspergillus sp. ZZ1861 in rice solid and potato dextrose broth liquid media. The structures of these isolated compounds were determined based on their HRESIMS data, NMR spectral analyses, and data from ECD, NMR, and optical rotation calculations. Emericelactones F and G, 20R,25S-preshamixanthone, 20R,25R-preshamixanthone, phthalimidinic acid A, phthalimidinic acid B, aspergilol G, and 2-hydroxyemodic amide are eight previously undescribed compounds and (S)-2-(5-hydroxymethyl-2-formylpyrrol-1-yl) propionic acid lactone is reported from a natural resource for the first time. It is also the first report of the configurations of 25S-O-methylarugosin A, 25R-O-methylarugosin A, 5R-(+)-9-hydroxymicroperfuranone, and 5R-(+)-microperfuranone. Phthalimidinic acid A, phthalimidinic acid B, aspergilol G, and 2-hydroxyemodic amide have antifungal activity against Candida albicans with MIC values of 1.56, 3.12, 1.56, and 12.5 μg/mL, respectively, 20R,25S-preshamixanthone (MIC 25 μg/mL) shows antibacterial activity against Escherichia coli, and 20R,25R-preshamixanthone exhibits antimicrobial activity against all three tested pathogens of methicillin-resistant Staphylococcus aureus, E. coli, and C. albicans with MIC values of 50, 25, 25 μg/mL, respectively.
Topics: Aspergillus; Microbial Sensitivity Tests; Anti-Bacterial Agents; Molecular Structure; Antifungal Agents; Structure-Activity Relationship; Candida albicans
PubMed: 38797256
DOI: 10.1016/j.phytochem.2024.114164 -
Biosensors & Bioelectronics Sep 2024The low abundance, heterogeneous expression, and temporal changes of miRNA in different cellular locations pose significant challenges for both the detection sensitivity...
The low abundance, heterogeneous expression, and temporal changes of miRNA in different cellular locations pose significant challenges for both the detection sensitivity of miRNA liquid biopsy and intracellular imaging. In this work, we report an intelligently assembled biosensor based on catalytic hairpin assembly (CHA) and aggregation-induced emission (AIE), named as catalytic hairpin aggregation-induced emission (CHAIE), for the ultrasensitive detection and intracellular imaging of miRNA-155. To achieve such goal, tetraphenylethylene-N (TPE-N) is used as AIE luminogen (AIEgen), while graphene oxide is introduced to quench the fluorescence. When the target miRNA is present, CHA reaction is triggered, causing the AIEgen to self-assemble with the hairpin DNA. This will restrict the intramolecular rotation of the AIEgen and produce a strong AIE fluorescence. Interestingly, CHAIE does not require any enzyme or expensive thermal cycling equipment, and therefore provides a rapid detection. Under optimal conditions, the proposed biosensor can determine miRNA in the concentration range from 2 pM to 200 nM within 30 min, with the detection limit of 0.42 pM. The proposed CHAIE biosensor in this work offers a low background signal and high sensitivity, making it applicable for highly precise spatiotemporal imaging of target miRNA in living cells.
Topics: Graphite; MicroRNAs; Biosensing Techniques; Humans; Nanocomposites; Fluorescent Dyes; Limit of Detection; Stilbenes; Catalysis; Optical Imaging; Spectrometry, Fluorescence; Fluorescence
PubMed: 38797033
DOI: 10.1016/j.bios.2024.116416