Supramolecular Assembly in Live Cells Mapped by Real-Time Phasor-Fluorescence Lifetime Imaging.

The complex dynamics and transience of assembly pathways in living systems complicate the understanding of these molecular to nanoscale processes. Current technologies are unable to track the molecular events leading to the onset of assembly, where real-time information is imperative to correlate their rich biology. Using a chemically designed pro-assembling molecule, we map its transformation into nanofibers and their fusion with endosomes to form hollow fiber clusters. Tracked by phasor-fluorescence lifetime imaging (phasor-FLIM) in epithelial cells (L929, A549, MDA-MB 231) and correlative light-electron microscopy and tomography (CLEM), spatiotemporal splicing of the assembly events shows time-correlated metabolic dysfunction. The biological impact begins with assembly-induced endosomal disruption that reduces glucose transport into the cells, which, in turn, stymies mitochondrial respiration.

Unraveling Eumelanin Radical Formation by Nanodiamond Optical Relaxometry in a Living Cell.

Defect centers in a nanodiamond (ND) allow the detection of tiny magnetic fields in their direct surroundings, rendering them as an emerging tool for nanoscale sensing applications. Eumelanin, an abundant pigment, plays an important role in biology and material science. Here, for the first time, we evaluate the comproportionation reaction in eumelanin by detecting and quantifying semiquinone radicals through the nitrogen-vacancy color center. A thin layer of eumelanin is polymerized on the surface of nanodiamonds (NDs), and depending on the environmental conditions, such as the local pH value, near-infrared, and ultraviolet light irradiation, the radicals form and react in situ. By combining experiments and theoretical simulations, we quantify the local number and kinetics of free radicals in the eumelanin layer. Next, the ND sensor enters the cells via endosomal vesicles. We quantify the number of radicals formed within the eumelanin layer in these acidic compartments by applying optical relaxometry measurements. In the future, we believe that the ND quantum sensor could provide valuable insights into the chemistry of eumelanin, which could contribute to the understanding and treatment of eumelanin- and melanin-related diseases.

A Pythium myriotylum Small Cysteine-Rich Protein Triggers Immune Responses in Diverse Plant Hosts.

The oomycete Pythium myriotylum is a necrotrophic pathogen that infects many crop species worldwide, including ginger, soybean, tomato, and tobacco. Here, we identified a P. myriotylum small cysteine-rich protein, PmSCR1, that induces cell death in Nicotiana benthamiana by screening small, secreted proteins that were induced during infection of ginger and did not have a predicted function at the time of selection. Orthologs of PmSCR1 were found in other Pythium species, but these did not have cell death-inducing activity in N. benthamiana. PmSCR1 encodes a protein containing an auxiliary activity 17 family domain and triggers multiple immune responses in host plants. The elicitor function of PmSCR1 appears to be independent of enzymatic activity, because the heat inactivation of PmSCR1 protein did not affect PmSCR1-induced cell death or other defense responses. The elicitor function of PmSCR1 was also independent of BAK1 and SOBIR1. Furthermore, a small region of the protein, PmSCR186-211, is sufficient for inducing cell death. A pretreatment using the full-length PmSCR1 protein promoted the resistance of soybean and N. benthamiana to Phytophthora sojae and Phytophthora capsici infection, respectively. These results reveal that PmSCR1 is a novel elicitor from P. myriotylum, which exhibits plant immunity-inducing activity in multiple host plants. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Detection of Few Hydrogen Peroxide Molecules Using Self-Reporting Fluorescent Nanodiamond Quantum Sensors.

Hydrogen peroxide (H2O2) plays an important role in various signal transduction pathways and regulates important cellular processes. However, monitoring and quantitatively assessing the distribution of H2O2 molecules inside living cells requires a nanoscale sensor with molecular-level sensitivity. Herein, we show the first demonstration of sub-10 nm-sized fluorescent nanodiamonds (NDs) as catalysts for the decomposition of H2O2 and the production of radical intermediates at the nanoscale. Furthermore, the nitrogen-vacancy quantum sensors inside the NDs are employed to quantify the aforementioned radicals. We believe that our method of combining the peroxidase-mimicking activities of the NDs with their intrinsic quantum sensor showcases their application as self-reporting H2O2 sensors with molecular-level sensitivity and nanoscale spatial resolution. Given the robustness and the specificity of the sensor, our results promise a new platform for elucidating the role of H2O2 at the cellular level.

In Situ Assembly of Platinum(II)-Metallopeptide Nanostructures Disrupts Energy Homeostasis and Cellular Metabolism.

Nanostructure-based functions are omnipresent in nature and essential for the diversity of life. Unlike small molecules, which are often inhibitors of enzymes or biomimetics with established methods of elucidation, we show that functions of nanoscale structures in cells are complex and can implicate system-level effects such as the regulation of energy and redox homeostasis. Herein, we design a platinum(II)-containing tripeptide that assembles into intracellular fibrillar nanostructures upon molecular rearrangement in the presence of endogenous H2O2. The formed nanostructures blocked metabolic functions, including aerobic glycolysis and oxidative phosphorylation, thereby shutting down ATP production. As a consequence, ATP-dependent actin formation and glucose metabolite-dependent histone deacetylase activity are downregulated. We demonstrate that assembly-driven nanomaterials offer a rich avenue to achieve broad-spectrum bioactivities that could provide new opportunities in drug discovery.

Nanodiamond Theranostic for Light-Controlled Intracellular Heating and Nanoscale Temperature Sensing.

Temperature is an essential parameter in all biological systems, but information about the actual temperature in living cells is limited. Especially, in photothermal therapy, local intracellular temperature changes induce cell death but the local temperature gradients are not known. Highly sensitive nanothermometers would be required to measure and report local temperature changes independent of the intracellular environment, including pH or ions. Fluorescent nanodiamonds (ND) enable temperature sensing at the nanoscale independent of external conditions. Herein, we prepare ND nanothermometers coated with a nanogel shell and the photothermal agent indocyanine green serves as a heat generator and sensor. Upon irradiation, programmed cell death was induced in cancer cells with high spatial control. In parallel, the increase in local temperature was recorded by the ND nanothermometers. This approach represents a great step forward to record local temperature changes in different cellular environments inside cells and correlate these with thermal biology.

Aluminum and polyanion-doping to improve structural and moisture stability of Ni-rich layered oxides for lithium-ion batteries.

Ni-rich layered materials LiNi0.8Co0.1Mn0.1O2 attracts extensive interest to build high-performance lithium-ion batteries, but ground challenges, e.g., unfavorable phase transfer and interfacial parasitic reactions during cycling, especially after being exposure to the air for a long time, greatly limit their practical utilization. Here, we prove that those issues of Ni-rich layered materials can be alleviated by concurrently incorporating the Al3+ and PO34-, and conduct corresponding comprehensive studies to explore mechanisms of the enhanced electrochemical performances. It is suggested that the phase transition (H2 to H3) that related to the lattice contraction can be suppressed after Al3+ and PO34- co-doping, leading to improved cycling stability. Additionally, the co-doping successfully mitigates the chemical reaction between the Ni-based oxides and the ambient air, significantly improving the reversibility of lithium intercalation and charge transfer kinetics against long-time storage. Specifically, the Al3+ and PO34- co-doped material maintains 94.1% capacity retention of 150 cycles before storage, and 73.6% capacity retention of 100 cycles after being stored in ambient air for 30 days, which is much better than that of the undoped one.

Grooved Microneedle Patch Augments Adoptive T Cell Therapy Against Solid Tumors via Diverting Regulatory T Cells.

The efficacy of adoptive T cell therapy (ACT) for the treatment of solid tumors remains challenging. In addition to the poor infiltration of effector T (Teff) cells limited by the physical barrier surrounding the solid tumor, another major obstacle is the extensive infiltration of regulatory T (Treg) cells, a major immunosuppressive immune cell subset, in the tumor microenvironment. Here, this work develops a grooved microneedle patch for augmenting ACT, aiming to simultaneously overcome physical and immunosuppressive barriers. The microneedles are engineered through an ice-templated method to generate the grooved structure for sufficient T-cell loading. In addition, with the surface modification of chemokine CCL22, the MNs could not only directly deliver tumor-specific T cells into solid tumors through physical penetration, but also specifically divert Treg cells from the tumor microenvironment to the surface of the microneedles via a cytokine concentration gradient, leading to an increase in the ratio of Teff cells/Treg cells in a mouse melanoma model. Consequently, this local delivery strategy of both T cell receptor T cells and chimeric antigen receptor T cells via the CCL22-modified grooved microneedles as a local niche could significantly enhance the antitumor efficacy and reduce the on-target off-tumor toxicity of ACT.

Recent Developments of Nanodiamond Quantum Sensors for Biological Applications.

Measuring certain quantities at the nanoscale is often limited to strict conditions such as low temperature or vacuum. However, the recently developed nanodiamond (ND) quantum sensing technology shows great promise for ultrasensitive diagnosis and probing subcellular parameters at ambient conditions. Atom defects (i.e., N, Si) within the ND lattice provide stable emissions and sometimes spin-dependent photoluminescence. These unique properties endow ND quantum sensors with the capacity to detect local temperature, magnetic fields, electric fields, or strain. In this review, some of the recent, most exciting developments in the preparation and application of ND sensors to solve current challenges in biology and medicine including ultrasensitive detection of virions and local sensing of pH, radical species, magnetic fields, temperature, and rotational movements, are discussed.

The sarcopenia index is an effective predictor for malnutrition in patients with liver cirrhosis.

AIM: Reliable and valid predictors of malnutrition in patients with cirrhosis remain scarce, especially easily accessible blood indicators. Thus, this study aimed to investigate the validity of the sarcopenia index (serum creatinine/serum cystatin C × 100) as a tool in assessing the nutritional status of patients with cirrhosis. METHODS: This prospective cohort study included 109 patients with cirrhosis who were hospitalised in Renmin Hospital of Wuhan University from August 2020 to June 2021. Malnutrition was diagnosed by the Global Leadership Initiative on Malnutrition criteria. Multivariable logistic regression was used to examine the relationship between sarcopenia index and malnutrition. The area under the receiver operating characteristic curve was used to evaluate the diagnostic performance of sarcopenia index. By contrast, we evaluated the subjective global assessment and traditional nutrition-related indicators. RESULTS: Of the 109 included patients, 71 (65.1%) were diagnosed with malnutrition. The sarcopenia index was significantly lower in malnourished patients (56.39 ± 15.23) compared with well-nourished patients (74.95 ± 13.18, p < 0.001). In addition, the sarcopenia index was independently correlated with malnutrition (p < 0.001). The sarcopenia index was a good tool to predict malnutrition (area under curve = 0.833), which performed better than the subjective global assessment (area under curve = 0.782) and cholinesterase (area under curve = 0.812). A low sarcopenia index indicated longer hospital stay and higher risk of 90-day re-hospitalisation. CONCLUSION: Malnutrition is highly prevalent in this population. The sarcopenia index seems to be a good predictor in nutritional assessment of patients with cirrhosis.

pH-Induced Electrostatic Interaction between Polyacrylates and Amino-Functionalized Graphene Oxide on Stability and Coating Performances.

Electrostatic interaction between polymers and nanofillers is of great importance for the properties and design of their composites. Polyacrylates with carboxyl, hydroxyl and acylamino groups were synthesized via emulsion polymerization and marked as P(MMA-BA-AA), P(MMA-BA-HEA) and P(MMA-BA-AM), respectively. Amino-functionalized graphene oxide (NGO) was prepared by Hoffman rearrangement using GO as the raw material. The polyacrylate composites were prepared by mixing NGO with each of the three kinds of polyacrylate. Effects of pH and NGO amounts on the properties of polyacrylate composites were studied. It was found that the surface charge of polyacrylate and NGO had the greatest effect on the composite properties. P(MMA-BA-AM)/NGO was not stable at any pH (2-8). With the same NGO amount of 0.1 wt%, the toughening effect of NGO on P(MMA-BA-AA) was larger than that on P(MMA-BA-HEA). The break strength of P(MMA-BA-AA)/NGO and P(MMA-BA-HEA)/NGO increased to 5.22 MPa by 47% and 3.08 MPa by 31%, respectively. NGO could increase the thermal stability of P(MMA-BA-AA) and P(MMA-BA-HEA) to different degrees. The polyacrylate film-forming processes were tested, and it showed that NGO influenced polyacrylate through the whole film-forming process. The results provide potential methods for the design of polymer-based nanocomposites.

Fluorescent nanodiamonds encapsulated by Cowpea Chlorotic Mottle Virus (CCMV) proteins for intracellular 3D-trajectory analysis.

Long-term tracking of nanoparticles to resolve intracellular structures and motions is essential to elucidate fundamental parameters as well as transport processes within living cells. Fluorescent nanodiamond (ND) emitters provide cell compatibility and very high photostability. However, high stability, biocompatibility, and cellular uptake of these fluorescent NDs under physiological conditions are required for intracellular applications. Herein, highly stable NDs encapsulated with Cowpea chlorotic mottle virus capsid proteins (ND-CP) are prepared. A thin capsid protein layer is obtained around the NDs, which imparts reactive groups and high colloidal stability, while retaining the opto-magnetic properties of the coated NDs as well as the secondary structure of CPs adsorbed on the surface of NDs. In addition, the ND-CP shows excellent biocompatibility both in vitro and in vivo. Long-term 3D trajectories of the ND-CP with fine spatiotemporal resolutions are recorded; their intracellular motions are analyzed by different models, and the diffusion coefficients are calculated. The ND-CP with its brilliant optical properties and stability under physiological conditions provides us with a new tool to advance the understanding of cell biology, e.g., endocytosis, exocytosis, and active transport processes in living cells as well as intracellular dynamic parameters.

Surface Modification Design for Improving the Strength and Water Vapor Permeability of Waterborne Polymer/SiO2 Composites: Molecular Simulation and Experimental Analyses.

Polymer-based nanocomposites properties are greatly affected by interfacial interaction. Polyacrylate nanocomposites have been widely studied, but few studies have been conducted on their interface mechanism. Therefore, there was an urgent demand for providing a thorough understanding of the polymethyl acrylate/SiO2 (PMA/SiO2) nanocomposites to obtain the desired macro-performance. In this paper, a methodology, which combined molecular dynamics simulation with experimental researches, was established to expound the effect of the surface structure of SiO2 particles which were treated with KH550, KH560 or KH570 (KH550-SiO2, KH560-SiO2 and KH570-SiO2) on the mechanical characteristic and water vapor permeability of polymethyl acrylate/SiO2 nanocomposites. The polymethyl acrylate/SiO2 nanocomposites were analyzed in binding energy and mean square displacement. The results indicate that PMA/KH570-SiO2 had the highest tensile strength, while PMA/KH550-SiO2 had the highest elongation at break at the same filler content; KH550-SiO2 spheres can significantly improve water vapor permeability of polyacrylate film.

Fabrication and investigation on Ag nanowires/TiO2 nanosheets/graphene hybrid nanocomposite and its water treatment performance.

In this paper, a novel Ag nanowires/TiO2 nanosheets/graphene nanocomposite was fabricated via a facile method of hydrothermal and calcination, and then the water treatment performance of it was evaluated for methylene blue (MB) and Escherichia coli removal. The as-prepared Ag nanowires/TiO2 nanosheets/graphene nanocomposite was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), UV-visible diffuse reflection spectroscopy (DRS), molecular dynamics simulation, and gas chromatography-mass spectrometry (GC-MS). All data revealed that the Ag/TiO2/graphene nanocomposite showed a rich cell structure. The photocatalytic activity of Ag/TiO2/graphene nanocomposite is higher than those of pristine TiO2 nanosheets and TiO2/graphene nanocomposite. Under optimized conditions, the degradation efficiency was 100% and 71% for MB (30 mg/L) and with 10 mg Ag/TiO2/graphene nanocomposite under UV and visible light irradiation for 2 h, respectively. Ag/TiO2/graphene also showed excellent bacteria-killing activity. Meanwhile, the Ag/TiO2/graphene nanocomposite exhibited microstructure stability and cyclic stability. The water treatment performance was enhanced mainly attributed to the excellent adsorption performance of graphene and the high efficiency in separation of electron-hole pairs induced by the remarkable synergistic effects of TiO2, Ag, and graphene. On the basis of the experimental results, the photocatalytic mechanism and MB degradation mechanism were proposed. It is hoped that our work could avert the misleading message to the readership, hence offering a valuable source of reference on fabricating composite photocatalyst with stable microstructure and excellent performance for their application in the environment clean-up. Graphical abstract.

Aligned 3D porous polyurethane scaffolds for biological anisotropic tissue regeneration.

A green fabrication process (organic solvent-free) of artificial scaffolds is required in tissue engineering field. In this work, a series of aligned three-dimensional (3D) scaffolds are made from biodegradable waterborne polyurethane (PU) emulsion via directional freeze-drying method to ensure no organic byproducts. After optimizing the concentration of polymer in the emulsion and investigating different freezing temperatures, an aligned PUs scaffold (PU14) generated from 14 wt% polymer content and processed at -196°C was selected based on the desired oriented porous structure (pore size of 32.5 ± 9.3 µm, porosity of 92%) and balanced mechanical properties both in the horizontal direction (strength of 41.3 kPa, modulus of 72.3 kPa) and in the vertical direction (strength of 45.5 kPa, modulus of 139.3 kPa). The response of L929 cells and the regeneration of muscle tissue demonstrated that such pure material-based aligned 3D scaffold can facilitate the development of orientated cells and anisotropic tissue regeneration both in vitro and in vivo. Thus, these pure material-based scaffolds with ordered architecture have great potentials in tissue engineering for biological anisotropic tissue regeneration, such as muscle, nerve, spinal cord and so on.

Nanofibrous scaffold from electrospinning biodegradable waterborne polyurethane/poly(vinyl alcohol) for tissue engineering application.

A series of nanofibrous scaffolds, free of organic solvents, are prepared by electrospinning biodegradable waterborne polyurethane (BWPU) emulsion blending with aqueous poly(vinyl alcohol)(PVA). Tuning the proration of BWPU to PVA, various nanofibers with diameter from 370 to 964 nm are obtained. Strong intermolecular interaction existing between them benefits to the electrospun of BWPU emulsion, which is demonstrated by dynamic thermomechanical analysis and Fourier transform infrared spectroscopy. The nontoxic nanofibrous scaffolds with porous structure, which is similar to the natural extracellular matrix, favor to the attachment and proliferation of the L929 fibroblasts. Thus, the scaffolds are promising to be used as biomaterials for many natural tissues repair.

Synthesis and characterization of biodegradable lysine-based waterborne polyurethane for soft tissue engineering applications.

Biomaterials for soft tissue engineering scaffolds require a combination of multiple properties including suitable mechanical properties, biodegradability, and biocompatibility. In this work, a series of light-crosslinking waterborne polyurethanes (LWPUs) were prepared using l-lysine ethyl ester diisocyanate (LDI), 1,3-propanediol (PDO) and l-lysine as hard segments and poly(ε-caprolactone) (PCL) and poly(ethylene glycol) (PEG) as soft segments. The obtained LWPUs exhibited appropriate stretchability with a break elongation of 1400-2500% and an excellent strength of 12-18 MPa, which could admirably meet the requirements for soft tissue engineering scaffolds. In addition, the hydrophilic surfaces of LWPUs could effectively reduce protein adsorption and platelet adhesion and favor cell proliferation compared with traditional biomedical polyurethanes. The ultimate degradation products of LWPUs were proven to be nontoxic in a cytotoxicity test. More interestingly, a cytokine release test of macrophages adherent to the LWPU film surfaces shows that these macrophages secreted less pro-inflammation cytokine TNF-α and more anti-inflammation cytokine IL-10 after 3 days' culture, indicating that LWPUs possess the potential ability to aid in the transition of macrophages toward a wound healing phenotype. Furthermore, the LWPU films could support the adhesion and proliferation of endothelial cells. Thus, the obtained LWPUs have great potential for applications in soft tissue engineering scaffolds for tissue repair and wound healing.

All-Cellulose-based flexible Zinc-Ion battery enabled by waste pomelo peel.

Aqueous zinc-ion batteries are attracting extensive attention due to the long-term service life and credible safety as well as the superior price performance between the low cost of manufacture and high energy density. The fabrication of inexpensive, high-performance flexible solid-state zinc-ion batteries, thus, are urgently need for the blooming wearable electronics. Herein, as a proof-of-concept study of waste into wealth, cellulose flakes derived from waste pomelo peel are utilized as the substrate for electrodes and hydrogel electrolytes into a flexible rocking-chair zinc-ion battery. The unique sandwich-type structure holding the flake-like cellulose substrate and linear carbon nanotubes endows the flexible cathode and anode with fast ion and electron transportation. The obtained cellulose-based hydrogel electrolytes on account of special affinity with aqueous ZnSO4 electrolyte output an excellent ionic conductivity. The assembled flexible rocking-chair zinc-ion battery benefitting from the synergistic effect of sandwich-type electrodes and cellulose-based hydrogel electrolytes demonstrates outstanding electrochemical performance and mechanical properties. This work not only puts up an effective roadmap for flexible battery devices, but also reveals the great potential of waste biomass materials in energy storage applications.