Explore the vast range of titles available.

Mitochondria play a critical role in generating energy to support the entire lifecycle of biological cells, yet it is still unclear how their morphological structures evolve to regulate their functionality. Conventional fluorescence microscopy can only provide ~300 nm resolution, which is insufficient to visualize mitochondrial cristae. Here, we developed an enhanced squaraine variant dye (MitoESq-635) to study the dynamic structures of mitochondrial cristae in live cells with a superresolution technique. The low saturation intensity and high photostability of MitoESq-635 make it ideal for long-term, high-resolution (stimulated emission depletion) STED nanoscopy. We performed time-lapse imaging of the mitochondrial inner membrane over 50 min (3.9 s per frame, with 71.5 s dark recovery) in living HeLa cells with a resolution of 35.2 nm. The forms of the cristae during mitochondrial fusion and fission can be clearly observed. Our study demonstrates the emerging capability of optical STED nanoscopy to investigate intracellular physiological processes with nanoscale resolution for an extended period of time. Live cell imaging of mitochondrial cristae is challenged by the unsuitability of current fluorescent probes and high phototoxicity. Here the authors develop a squarine variant probe (MitoESq-635) that is capable of longitudinal imaging of cristae with STED with minimal phototoxicity.

Many kinds of nanoparticles and organic dyes as fluorescent probes have been used in the stimulated emission depletion (STED) nanoscopy. Due to high toxicity, photobleaching and non-water solubility, these fluorescent probes are hard to apply in living cell imaging. Here, we report a new fluorescence carbon dots (FNCDs) with high photoluminescence quantum yield (56%), low toxicity, anti-photobleaching and good water-solubility that suitable for live-cell imaging can be obtained by doping fluorine element. Moreover, the FNCDs can stain the nucleolus and tunneling nanotubes (TNTs) in the living cell. More importantly, for STED nanoscopy imaging, the FNCDs effectively depleted background signals and improved imaging resolution. Furthermore, the lateral resolution of single FNCDs size under the STED nanoscopy is up to 22.1 nm for FNCDs deposited on a glass slide was obtained. And because of their good water dispersibility, the higher resolution of single FNCDs size in the nucleolus of a living cell can be up to 19.7 nm. After the image optimization steps, the fine fluorescence images of TNTs diameter with ca. 75 nm resolution is obtained living cell, yielding a threefold enhancement compared with that in confocal imaging. Additionally, the FNCDs show excellent photobleaching resistance after 1,000 scan cycles in the STED model. All results show that FNCDs have significant potential for application in STED nanoscopy.

Laser scanning microscopy has inherent tradeoffs between imaging speed, field of view (FOV), and spatial resolution due to the limitations of sophisticated mechanical and optical setups, and deep learning networks have emerged to overcome these limitations without changing the system. Here, we demonstrate deep learning autofluorescence-harmonic microscopy (DLAM) based on self-alignment attention-guided residual-in-residual dense generative adversarial networks to close the gap between speed, FOV, and quality. Using the framework, we demonstrate label-free large-field multimodal imaging of clinicopathological tissues with enhanced spatial resolution and running time advantages. Statistical quality assessments show that the attention-guided residual dense connections minimize the persistent noise, distortions, and scanning fringes that degrade the autofluorescence-harmonic images and avoid reconstruction artifacts in the output images. With the advantages of high contrast, high fidelity, and high speed in image reconstruction, DLAM can act as a powerful tool for the noninvasive evaluation of diseases, neural activity, and embryogenesis.A self-alignment attention-guided residual-in-residual dense generative adversarial networks architecture closes the gap between speed, field of view, and image quality of label-free nonlinear optical microscopes which are notoriously slow.

In this work, we constructed a Collagen I–Matrigel composite extracellular matrix (ECM). The composite ECM was used to determine the influence of the local collagen fiber orientation on the collective intravasation ability of tumor cells. We found that the local fiber alignment enhanced cell–ECM interactions. Specifically, metastatic MDA-MB-231 breast cancer cells followed the local fiber alignment direction during the intravasation into rigid Matrigel (∼10 mg/mL protein concentration).

Metallic and semimetallic mesoporous frameworks are of great importance owing to their unique properties and broad applications. However, semimetallic mesoporous structures cannot be obtained by the traditional template-mediated strategies due to the inevitable hydrolytic reaction of semimetal compounds. Therefore, it is yet challenging to fabricate mesoporous semimetal nanostructures, not even mention controlling their pore sizes. Here we develop a facile and robust selective etching route to synthesize monodispersed mesoporous antimony nanospheres (MSbNSs). The pore sizes of MSbNSs are tunable by carefully controlling the partial oxidation of Sb nuclei and the selective etching of the as-formed Sb 2 O 3 . MSbNSs show a wide absorption from visible to second near-infrared (NIR-II) region. Moreover, PEGylated MSbNSs are degradable and the degradation mechanism is further explained. The NIR-II photothermal performance of MSbNSs is promising with a high photothermal conversion efficiency of ~44% and intensive NIR-II photoacoustic signal. MSbNSs show potential as multifunctional nanomedicines for NIR-II photoacoustic imaging guided synergistic photothermal/chemo therapy in vivo. Our selective etching process would contribute to the development of various semimetallic mesoporous structures and efficient multimodal nanoplatforms for theranostics. The properties of mesoporous nanomaterials have been exploited for several applications, including drug delivery and NIR-II photoacoustic imaging. Here, the authors design monodispersed semimetallic mesoporous antimony nanospheres with photothermal conversion efficiency in the second near-infrared range and drug loading capacity, showing their potential for cancer photothermal/chemo therapy.

Inorganic nanomaterials with intrinsic singlet oxygen (1O2) generation capacity, are emerged yet dynamically developing materials as nano‐photosensitizers (NPSs) for photodynamic therapy (PDT). Compared to previously reported nanomaterials that have been used as either carriers to load organic PSs or energy donors to excite the attached organic PSs through a Foster resonance energy transfer process, these NPSs possess intrinsic 1O2 generation capacity with extremely high 1O2 quantum yield (e.g., 1.56, 1.3, 1.26, and 1.09) than any classical organic PS reported to date, and thus are facilitating to make a revolution in PDT. In this review, the recent advances in the development of various inorganic nanomaterials as NPSs, including metal‐based (gold, silver, and tungsten), metal oxide‐based (titanium dioxide, tungsten oxide, and bismuth oxyhalide), metal sulfide‐based (copper and molybdenum sulfide), carbon‐based (graphene, fullerene, and graphitic carbon nitride), phosphorus‐based, and others (hybrids and MXenes‐based NPSs) are summarized, with an emphasis on the design principle and 1O2 generation mechanism, and the photodynamic therapeutic performance against different types of cancers. Finally, the current challenges and an outlook of future research are also discussed. This review may provide a comprehensive account capable of explaining recent progress as well as future research of this emerging paradigm. Inorganic nano‐photosensitizers possess higher extinction coefficient, resistance to photobleaching, larger absorption cross‐section, and high singlet oxygen quantum yield than their organic counterparts. These fascinating physiochemical features endow them with promising potential for reactive oxygen species‐mediated photodynamic tumor cell killing, antibacterial therapy, thermal ablation‐induced antitumor photothermal therapy, and simultaneous tumor diagnosis and treatment for multimodal cancer theranostics.

In this work, we designed a sensitivity-enhanced surface plasmon resonance biosensor structure based on silicon nanosheet and two-dimensional transition metal dichalcogenides. This configuration contains six components: SF10 triangular prism, gold thin film, silicon nanosheet, two-dimensional MoS 2 /MoSe 2 /WS 2 /WSe 2 (defined as MX 2 ) layers, biomolecular analyte layer and sensing medium. The minimum reflectivity, sensitivity as well as the Full Width at Half Maximum of SPR curve are systematically examined by using Fresnel equations and the transfer matrix method in the visible and near infrared wavelength range (600 nm to 1024 nm). The variation of the minimum reflectivity and the change in resonance angle as the function of the number of MX 2 layers are presented respectively. The results show that silicon nanosheet and MX 2 layers can be served as effective light absorption medium. Under resonance conditions, the electrons in these additional dielectric layers can be transferred to the surface of gold thin film. All silicon-MX 2 enhanced sensing models show much better performance than that of the conventional sensing scheme where pure Au thin film is used, the highest sensitivity can be achieved by employing 600 nm excitation light wavelength with 35 nm gold thin film and 7 nm thickness silicon nanosheet coated with monolayer WS 2 .

A light beam propagating over an infinite anti-diffracting distance requires infinite power to preserve its shape. However, the fundamental barrier of finite power in free space has made the problem of diffraction insurmountable in recent decades. To overcome this limitation, we report an approach that employs the multiple energy oscillation mechanism, thereby permitting the creation of a light beam with an ultralong anti-diffracting distance in free space. A versatile optical pen is therefore developed to manipulate the number, amplitude, position and phase of energy oscillations for a focusing lens so that multiple energy oscillations can be realized. A light beam with a tunable number of energy oscillations is eventually generated in free space and propagates along a wavy trajectory. This work will enable the extension of non-diffractive light beams to an expanded realm and facilitate extensive developments in optics and other research fields, such as electronics and acoustics. Anti-diffracting propagation of light beams over infinite distance requires infinite power. Here, the authors develop an approach that uses multiple energy oscillation mechanisms to overcome this limitation, developing a versatile optical pen.

Timely and accurately identification of the novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can greatly contribute to monitoring and controlling the global pandemic. This study gained theoretical insight into a novel phase-modulation plasmonic biosensor working in the near-infrared (NIR) regime, which can be employed for sensitive detection of SARS-CoV-2 and its spike (S) glycoprotein. The proposed plasmonic biosensor was created by integrating two-dimensional (2D) Van der Waals heterostructures, including tellurene and carboxyl-functionalized molybdenum disulfide (MoS2) layers, with transparent indium tin oxide (ITO) film. Excellent biosensing performance can be achieved under the excitation of 1550 nm by optimizing the thickness of ITO film and tellurene-MoS2 heterostructures. For a sensing interface refractive index change as low as 0.0012 RIU (RIU, refractive index unit), the optimized plasmonic configuration of 121 nm ITO film/three-layer tellurene/ten-layer MoS2-COOH can produce the highest detection sensitivity of 8.4069 × 104 degree/RIU. More importantly, MoS2-COOH layer can capture angiotensin-converting enzyme II, which is an ideal adsorption site for specifically binding SARS-CoV-2 S glycoprotein. Then, an excellent linear detection range for S glycoprotein and SARS-CoV-2 specimens is ∼0-301.67 nM and ∼0-67.8762 nM, respectively. This study thus offers an alternative strategy for rapidly performing novel coronavirus diagnosis in clinical applications.

Combined phototherapy and immunotherapy demonstrates strong potential in the treatment of metastatic cancers. An upconversion nanoparticle (UCNP) based antigen‐capturing nanoplatform is designed to synergize phototherapies and immunotherapy. In particular, this nanoplatform is constructed via self‐assembly of DSPE‐PEG‐maleimide and indocyanine green (ICG) onto UCNPs, followed by loading of the photosensitizer rose bengal (RB). ICG significantly enhances the RB‐based photodynamic therapy efficiency of UCNP/ICG/RB‐mal upon activation by a near‐infrared (NIR) laser, simultaneously achieving selective photothermal therapy. Most importantly, tumor‐derived protein antigens, arising from phototherapy‐treated tumor cells, can be captured and retained in situ, due to the functionality of maleimide, which further enhance the tumor antigen uptake and presentation by antigen‐presenting cells. The synergized photothermal, photodynamic, and immunological effects using light‐activated UCNP/ICG/RB‐mal induces a tumor‐specific immune response. In the experiments, intratumoral administration of UCNP/ICG/RB‐mal, followed by noninvasive irradiation with an NIR laser, destroys primary tumors and inhibits untreated distant tumors, using a poorly immunogenic, highly metastatic 4T1 mammary tumor model. With the simultaneous use of anti‐CTLA‐4, about 84% of the treated tumor‐bearing mice achieve long‐term survival and 34% of mice develop tumor‐specific immunity. Overall, this antigen‐capturing nanoplatform provides a promising approach for the treatment of metastatic cancers. An NIR‐triggered antigen‐capturing nanoplatform is designed to synergize photodynamic, photothermal, and immunotherapy for cancer treatment. The enhanced photothermal/photodynamic effects using the nanoplatform release tumor‐derived protein antigens, which in turn are captured and retained in situ by the nanoplatform. The enhanced uptake and presentation of antigens by antigen‐presenting cells facilitate a tumor‐specific immune response to inhibit tumor metastasis.