Biomimetic Smart Nanoplatform for Dual Imaging-Guided Synergistic Cancer Therapy

Developing an integrated multimodal diagnosis and therapeutics nanoplatform is of great importance to enhance the cancer therapy outcome. Herein, we report a highly efficient and biocompatible nanoplatform based on the...

Visualizing pyrazinamide action by live single cell imaging of phagosome acidification and Mycobacterium tuberculosis pH homeostasis

Mycobacterium tuberculosis (Mtb) segregates within multiple subcellular niches with different biochemical and biophysical properties that, upon treatment, may impact antibiotic distribution, accumulation, and efficacy. However, it remains unclear whether fluctuating intracellular microenvironments alter mycobacterial homeostasis and contribute to antibiotic enrichment and efficacy. Here, we describe a live dual-imaging approach to monitor host subcellular acidification and Mtb intrabacterial pH. By combining this approach with pharmacological and genetic perturbations, we show that Mtb can maintain its intracellular pH independently of the surrounding pH in human macrophages. Importantly, unlike bedaquiline (BDQ), isoniazid (INH) or rifampicin (RIF), the drug pyrazinamide (PZA) displays antibacterial efficacy by acting as protonophore which disrupts intrabacterial pH homeostasis in cellulo. By using Mtb mutants, we confirmed that intracellular acidification is a prerequisite for PZA efficacy in cellulo. We anticipate this imaging approach will be useful to identify host cellular environments that affect antibiotic efficacy against intracellular pathogens.

A core-shell Au@Cu2-xSe heterogeneous metal nanocomposite for photoacoustic and computed tomography dual-imaging-guided photothermal boosted chemodynamic therapy

Chemodynamic therapy (CDT) has aroused extensive attention for conquering cancers because of its high specificity and low invasiveness. Quick generation of hydroxyl radicals (·OH) during CDT could induce more irreparable damage to cancer cells. The generation rate of ·OH could be magnified via the selection of suitable nanocatalysts or under the assistance of exogenous thermal energy from photothermal therapy (PTT). Here, we construct a kind of monodisperse core-shell Au@Cu2-xSe heterogeneous metal nanoparticles (NPs) for PTT boosted CDT synergistic therapy. Due to the localized surface plasmon resonance (LSPR) coupling effect in the core-shell structure, the photothermal conversion efficiency of Au@Cu2-xSe NPs is up to 56.6%. The in situ generated heat from photothermal can then accelerate the Fenton-like reaction at Cu+ sites to produce abundant ·OH, which will induce apoptotic cell death by attacking DNA, contributing to a heat-boosted CDT. Both in vitro and in vivo results showed that after this synergistic therapy, tumors could be remarkably suppressed. Guided by photoacoustic (PA) and computed tomography (CT) imaging, the therapeutic effects were more specified. Our results revealed that PA and CT dual-imaging-guided PTT boosted CDT synergistic therapy based on core-shell Au@Cu2-xSe NPs is an effective cancer treatment strategy. Graphical Abstract

High-Speed Imaging Reveals the Bimodal Nature of Dense Core Vesicle Exocytosis and Jet Flow through the Fusion Pore

During exocytosis, the fusion of secretory vesicle with plasma membrane forms a pore that regulates release of neurotransmitter and peptide. Osmotic forces contribute to exocytosis but release through the pore is thought to occur by diffusion. Heterogeneity of fusion pore behavior has also suggested stochastic variation in a common exocytic mechanism, implying a lack of biological control. Imaging at millisecond resolution to observe the first events in exocytosis, we find that fusion pore duration is bimodal rather than stochastic. Loss of calcium sensor synaptotagmin 7 increases the proportion of slow events without changing the intrinsic properties of either class, indicating the potential for independent regulation. In addition, dual imaging shows a delay in the entry of external dye relative to release that indicates discharge at high velocity rather than strictly by diffusion.

Smart Gold-Polymer Nanostructures As Promising Drug Nanocarriers For Dual-Imaging Modality And Synergistic Chemo-Photothermal Therapy in Breast Cancer Cells

To improve the efficacy of cancer therapeutics, highly sensitive imaging with precise accuracy is mandatory for timely diagnosis and selection of strategic approaches. Despite recent advances in technologies associated with tumor imaging, the application of conventional single-mode imaging is the subject of debate. Herein, two types of pH-responsive gold-polymer nanostructures, GNSts and GNRs, containing CD and MTX, GNSts-MTX@CD-Pol and GNRs-MTX@CD-Pol were designed. Dual-imaging modalities (fluorescence and CT imaging) and synergistic chemo-photothermal therapy were examined in human breast cancer MDA-MB 231 cells. MTT assay showed NIR irradiation of cells pre-treated with synthesized nanoparticles promoted tumoricidal synergy via the reduction of survival rate after 48 hours in comparison with the control group (p<0.05), indicating a high absorption coefficient in the NIR area and efficient heat production rate. Flow cytometry, real-time PCR and western blot, analyses indicated an apoptotic cell death induced by the up-regulation of Caspases 3, 6, 7, 8, and 9, Bax, and Annexin-V, confirming the activation of intrinsic and extrinsic apoptosis pathways inside the host cells. The elevation of p27 and p53 in line with the increase of cell percent at the subG1 phase showed apoptotic changes and inhibition of dynamic cell growth compared to the non-treated cells (p<0.05). Evident fluorescence intensity at lower pH values (6.3) showed pH-dependent activity of nanoparticles internalized by surface folate receptor. Of note, we showed strong capability for CT imaging in cells incubated with GNSts-MTX@CD-Pol and GNRs-MTX@CD-Pol. Taken together, all data show that gold-polymer nanostructures have considerable capability in theranostic applications like simultaneous diagnostic imaging and therapy.