Positive regulation of oxidative phosphorylation by nuclear myosin 1 protects cells from metabolic reprogramming and tumorigenesis in mice

Metabolic reprogramming is one of the hallmarks of tumorigenesis. Here, we show that nuclear myosin 1 (NM1) serves as a key regulator of cellular metabolism. NM1 directly affects mitochondrial oxidative phosphorylation (OXPHOS) by regulating mitochondrial transcription factors TFAM and PGC1α, and its deletion leads to underdeveloped mitochondria inner cristae and mitochondrial redistribution within the cell. These changes are associated with reduced OXPHOS gene expression, decreased mitochondrial DNA copy number, and deregulated mitochondrial dynamics, which lead to metabolic reprogramming of NM1 KO cells from OXPHOS to aerobic glycolysis.This, in turn, is associated with a metabolomic profile typical for cancer cells, namely increased amino acid-, fatty acid-, and sugar metabolism, and increased glucose uptake, lactate production, and intracellular acidity. NM1 KO cells form solid tumors in a mouse model, suggesting that the metabolic switch towards aerobic glycolysis provides a sufficient carcinogenic signal. We suggest that NM1 plays a role as a tumor suppressor and that NM1 depletion may contribute to the Warburg effect at the onset of tumorigenesis.

pH-Responsive Upconversion Mesoporous Silica Nanospheres for Combined Multimodal Diagnostic Imaging and Targeted Photodynamic and Photothermal Cancer Therapy

Photodynamic therapy (PDT) and photothermal therapy (PTT) have gained considerable attention as potential alternatives to conventional cancer treatments. However, these approaches remain limited by low solubility, poor stability, and inefficient targeting of many common photosensitizers (PSs) and photothermal agents (PTAs). To overcome the aforementioned limitations, we engineered biocompatible and biodegradable tumor-targeted upconversion nanospheres with imaging capabilities. The multifunctional nanospheres consist of a sodium yttrium fluoride core doped with lanthanides (ytterbium, erbium, and gadolinium) and the PTA bismuth selenide (NaYF4:Yb/Er/Gd,Bi2Se3) enveloped in a mesoporous silica shell that encapsulates a PS, chlorin e6 (Ce6), within its pores. NaYF4:Yb/Er converts deeply penetrating near-infrared (NIR) light to visible light, which excites Ce6 to generate cytotoxic reactive oxygen species (ROS), while Bi2Se3 efficiently converts absorbed NIR light to heat. Additionally, Gd enables magnetic resonance imaging of the nanospheres. The mesoporous silica shell is coated with DPPC/cholesterol/DSPE-PEG to retain the encapsulated Ce6 and prevent serum protein adsorption and macrophage recognition that hinder tumor targeting. Finally, the coat is conjugated to the acidity-triggered rational membrane (ATRAM) peptide, which promotes specific and efficient internalization into malignant cells in the mildly acidic microenvironment of tumors. The nanospheres facilitated tumor magnetic resonance and thermal and fluorescence imaging and exhibited potent NIR laser light-induced anticancer effects in vitro and in vivo via combined ROS production and localized hyperthermia, with negligible toxicity to healthy tissue, hence markedly extending survival. Our results demonstrate that the ATRAM-functionalized, lipid/PEG-coated upconversion mesoporous silica nanospheres (ALUMSNs) offer multimodal diagnostic imaging and targeted combinatorial cancer therapy.

Light-driven self-assembly of spiropyran-functionalized covalent organic framework

Controlling the number of molecular switches and their relative positioning within porous materials is critical to their functionality and properties. The proximity of many molecular switches to one another can hinder or completely suppress their response. Herein, a synthetic strategy involving mixed linkers is used to control the distribution of spiropyran-functionalized linkers in a covalent organic framework (COF). The COF contains a spiropyran in each pore which exhibits excellent reversible photoswitching behavior to its merocyanine form in the solid state in response to UV/Vis light. The spiro-COF possesses an urchin-shaped morphology and exhibits a morphological transition to 2D nanosheets and vesicles in solution upon UV light irradiation. The merocyanine-equipped COFs are extremely stable and possess a more ordered structure with enhanced photoluminescence. This approach to modulating structural isomerization in the solid state is used to develop inkless printing media, while the photomediated polarity change is used for water harvesting applications.

pH-responsive upconversion mesoporous silica nanospheres for combined multimodal diagnostic imaging and targeted photodynamic and photothermal cancer therapy

Photodynamic therapy (PDT) and photothermal therapy (PTT) have garnered considerable interest as non-invasive cancer treatment modalities. However, these approaches remain limited by low solubility, poor stability and inefficient targeting of many common photosensitizers (PSs) and photothermal agents (PTAs). To overcome these limitations, we have designed biocompatible and biodegradable tumor-targeted upconversion nanospheres with imaging capabilities. The multifunctional nanospheres consist of a sodium yttrium fluoride core doped with lanthanides (ytterbium, erbium and gadolinium) and bismuth selenide (NaYF 4 :Yb/Er/Gd,Bi 2 Se 3 ) within a mesoporous silica shell that encapsulates a PS, Chlorin e6 (Ce6), in its pores. NaYF 4 :Yb/Er converts deeply penetrating near-infrared (NIR) light to visible light, which excites the Ce6 to generate cytotoxic reactive oxygen species (ROS), while the PTA Bi 2 Se 3 efficiently converts absorbed NIR light to heat. Additionally, Gd enables magnetic resonance imaging (MRI) of the nanospheres. The mesoporous silica shell is coated with lipid/polyethylene glycol (DPPC/cholesterol/DSPE-PEG) to ensure retention of the encapsulated Ce6 and minimize interactions with serum proteins and macrophages that impede tumor targeting. Finally, the coat is functionalized with the acidity-triggered rational membrane (ATRAM) peptide, which promotes specific and efficient internalization into cancer cells within the mildly acidic tumor microenvironment. Following uptake by cancer cells in vitro , NIR laser irradiation of the nanospheres caused substantial cytotoxicity due to ROS production and hyperthermia. The nanospheres facilitated tumor MRI and thermal imaging, and exhibited potent NIR laser light-induced antitumor effects in vivo via combined PDT and PTT, with no observable toxicity to healthy tissue, thereby substantially prolonging survival. Our results demonstrate that the ATRAM-functionalized, lipid/PEG-coated upconversion mesoporous silica nanospheres (ALUMSNs) offer multimodal diagnostic imaging and targeted combinatorial cancer therapy.

Synthesis of Self-Assembled Single Atomic Layer Gold Crystals-Goldene

We report, for the first time, a technique to synthesize free-standing, one-atom thick 2D gold crystals (namely, goldene) and self-assembled 2D periodic arrays of goldene. High-resolution transmission electron microscopy (HRTEM) imaging of goldene revealed herringbone and honeycomb lattices, which are primarily gold surface features due to its reconstruction. Imaging of these surface-only features by a nonsurface characterization technique such as HRTEM is an unequivocal proof of the absence of three-dimensionality in goldene. Atomic force microscopy confirmed 1-2 Å thickness of goldene. High-resolution X-ray photoelectron spectroscopy (HR-XPS), selective area electron diffraction, and energy-dispersive X-ray spectroscopy confirmed the chemical identity of goldene. We discovered the phenomenon of electric field-induced self-assembly of goldene supracrystals with a herringbone structure and developed an electric field printing (e-print) technique for goldene arrays. Goldene showed a semiconductor response with a knee voltage of ∼3.2 V, and I/V spectroscopy revealed periodic room temperature Coulomb blockade oscillations. These observations are consistent with the theoretical calculations reported in the literature predicting enhanced Coulombic interactions between gold valence electrons and the nucleus in stable 2D gold. Goldene exhibited multiple, intense, and well-resolved optical absorption peaks and several fine bands across the UV-vis region, and we calculated its optical band gap to be 3.59 eV. Magnetic force microscopy measurements of goldene periodic arrays showed a ∼5 mV peak amplitude confirming its ferromagnetism. Optical and magnetic properties of goldene are consistent with those reported in the literature for 2D planar gold clusters with less than 12 atoms.

Anti-tuberculosis drugs used in a directly observed treatment short course (DOTS) schedule alter endocrine patterns and reduce the ovarian reserve and oocyte quality in the mouse

CONTEXT

Tuberculosis is one of the major infectious diseases, with people of reproductive age group having a high risk of infection.

AIMS

The present study was designed to understand the consequences of anti-tuberculosis drugs (ATDs) used in DOTS (directly observed treatment short course) schedule on ovarian function.

METHODS

Adult female Swiss albino mice were orally administered with combinations of ATDs used in the DOTS schedule every day for 4weeks. At 2weeks after the cessation of ATDs administration, the endocrine changes and ovarian function were assessed in mice.

KEY RESULTS

Administration of ATDs to mice resulted in a prolonged estrous cycle, reduced ovarian follicle reserve, alteration in FSH, LH, and progesterone level, and decreased the number of ovulated oocytes. Further, the degree of fragmentation, degeneration, abnormal distribution of cytoplasmic organelles, abnormal spindle organisation, and chromosomal misalignment were higher in oocytes that were ovulated following superovulation. Blastocysts derived from ATDs treated mice had significantly lower total cell numbers and greater DNA damage. A marginal increase in the number of resorbed fetuses was observed in all the ATDs treated groups except in the multidrug resistance treatment group. Male progeny of ATDs treated mice had decreased sperm count and lower progressive motility, while female progeny exhibited a non-significant reduction in the number of oocytes ovulated.

CONCLUSIONS

Theresults of this study suggest that ATDs can have significant adverse effects on the ovarian reserve, cytoplasmic organisation of oocytes, and can potentially cause transgenerational changes.

IMPLICATIONS

The findings of the present study indicate ovarian toxicity of ATDs and warrant further research in the direction of identifying alternate drugs with minimal toxicity, and strategies to mitigate the ovarian toxicity induced by these drugs.

Protein mimetic amyloid inhibitor potently abrogates cancer-associated mutant p53 aggregation and restores tumor suppressor function

Missense mutations in p53 are severely deleterious and occur in over 50% of all human cancers. The majority of these mutations are located in the inherently unstable DNA-binding domain (DBD), many of which destabilize the domain further and expose its aggregation-prone hydrophobic core, prompting self-assembly of mutant p53 into inactive cytosolic amyloid-like aggregates. Screening an oligopyridylamide library, previously shown to inhibit amyloid formation associated with Alzheimer's disease and type II diabetes, identified a tripyridylamide, ADH-6, that abrogates self-assembly of the aggregation-nucleating subdomain of mutant p53 DBD. Moreover, ADH-6 targets and dissociates mutant p53 aggregates in human cancer cells, which restores p53's transcriptional activity, leading to cell cycle arrest and apoptosis. Notably, ADH-6 treatment effectively shrinks xenografts harboring mutant p53, while exhibiting no toxicity to healthy tissue, thereby substantially prolonging survival. This study demonstrates the successful application of a bona fide small-molecule amyloid inhibitor as a potent anticancer agent.

In vivo oral insulin delivery via covalent organic frameworks

With diabetes being the 7th leading cause of death worldwide, overcoming issues limiting the oral administration of insulin is of global significance. The development of imine-linked-covalent organic framework (nCOF) nanoparticles for oral insulin delivery to overcome these delivery barriers is herein reported. A gastro-resistant nCOF was prepared from layered nanosheets with insulin loaded between the nanosheet layers. The insulin-loaded nCOF exhibited insulin protection in digestive fluids in vitro as well as glucose-responsive release, and this hyperglycemia-induced release was confirmed in vivo in diabetic rats without noticeable toxic effects. This is strong evidence that nCOF-based oral insulin delivery systems could replace traditional subcutaneous injections easing insulin therapy.

Loss of β-Actin Leads to Accelerated Mineralization and Dysregulation of Osteoblast-Differentiation Genes during Osteogenic Reprogramming

Actin plays fundamental roles in both the cytoplasm and the cell nucleus. In the nucleus, β-actin regulates neuronal reprogramming by consolidating a heterochromatin landscape required for transcription of neuronal gene programs, yet it remains unknown whether it has a role in other differentiation models. To explore the potential roles of β-actin in osteogenesis, β-actin wild-type (WT) and β-actin knockout (KO) mouse embryonic fibroblasts (MEFs) are reprogrammed to osteoblast-like cells using small molecules in vitro. It is discovered that loss of β-actin leads to an accelerated mineralization phenotype (hypermineralization), accompanied with enhanced formation of extracellular hydroxyapatite microcrystals, which originate in the mitochondria in the form of microgranules. This phenotype is a consequence of rapid upregulation of mitochondrial genes including those involved in oxidative phosphorylation (OXPHOS) in reprogrammed KO cells. It is further found that osteogenic gene programs are differentially regulated between WT and KO cells, with clusters of genes exhibiting different temporal expression patterns. A novel function for β-actin in osteogenic reprogramming through a mitochondria-based mechanism that controls cell-mediated mineralization is proposed.

Covalent Organic Framework Embedded with Magnetic Nanoparticles for MRI and Chemo-Thermotherapy

Nanoscale imine-linked covalent organic frameworks (nCOFs) were first loaded with the anticancer drug Doxorubicin (Dox), coated with magnetic iron oxide nanoparticles (γ-Fe₂O₃ NPs), and stabilized with a shell of poly(l-lysine) cationic polymer (PLL) for simultaneous synergistic thermo-chemotherapy treatment and MRI imaging. The pH responsivity of the resulting nanoagents (γ-SD/PLL) allowed the release of the drug selectively within the acidic microenvironment of late endosomes and lysosomes of cancer cells (pH 5.4) and not in physiological conditions (pH 7.4). γ-SD/PLL could efficiently generate high heat (48 °C) upon exposure to an alternating magnetic field due to the nCOF porous structure that facilitates the heat conduction, making γ-SD/PLL excellent heat mediators in an aqueous solution. The drug-loaded magnetic nCOF composites were cytotoxic due to the synergistic toxicity of Dox and the effects of hyperthermia in vitro on glioblastoma U251-MG cells and in vivo on zebrafish embryos, but they were not significantly toxic to noncancerous cells (HEK293). To the best of our knowledge, this is the first report of multimodal MRI probe and chemo-thermotherapeutic magnetic nCOF composites.

Supercritical CO2 Processing Generates Aqueous Cisplatin Solutions with Enhanced Cancer Specificity

Cisplatin is a highly toxic material used clinically as a potent chemotherapeutic. While effective against some cancers, toxicity limits widespread use and low solubility confounds delivery. To formulate a better tolerated and more water-soluble form of cisplatin, we designed a rapid expansion of supercritical solutions (RESS) technique with supercritical carbon dioxide (sc-CO₂) to collect nanoclusters of cisplatin embedded in dry ice, in a dual-stage collection vessel cooled to liquid nitrogen temperature. These nanoclusters were solubilized in deionized water and further concentrated (up to 51.3 mM) by a Rotovap process, yielding stable cisplatin solutions with solubility up to 15 × (w/w) greater than that of normal cisplatin. Extensive material characterizations of the solutions were carried out to determine any chemical and/or structural changes of the RESS-processed cisplatin. In vitro cytotoxicity studies of these aqueous solutions showed increased cell viability and early apoptosis compared to equivalent concentrations of standard cisplatin solutions. In vivo studies using zebrafish embryos revealed that standard cisplatin solutions were acutely toxic and caused death of rapidly proliferating cells compared to RESS-processed cisplatin, which were better tolerated with reduced general cell death. Increased water solubility and matched chemical identity of RESS-processed aqueous cisplatin solutions indicate the potential to open up novel drug-delivery routes, which is beneficial for new pharmaceutical design and development.

pH-responsive high stability polymeric nanoparticles for targeted delivery of anticancer therapeutics

The practical application of nanoparticles (NPs) as chemotherapeutic drug delivery systems is often hampered by issues such as poor circulation stability and targeting inefficiency. Here, we have utilized a simple approach to prepare biocompatible and biodegradable pH-responsive hybrid NPs that overcome these issues. The NPs consist of a drug-loaded polylactic-co-glycolic acid (PLGA) core covalently 'wrapped' with a crosslinked bovine serum albumin (BSA) shell designed to minimize interactions with serum proteins and macrophages that inhibit target recognition. The shell is functionalized with the acidity-triggered rational membrane (ATRAM) peptide to facilitate internalization specifically into cancer cells within the acidic tumor microenvironment. Following uptake, the unique intracellular conditions of cancer cells degrade the NPs, thereby releasing the chemotherapeutic cargo. The drug-loaded NPs showed potent anticancer activity in vitro and in vivo while exhibiting no toxicity to healthy tissue. Our results demonstrate that the ATRAM-BSA-PLGA NPs are a promising targeted cancer drug delivery platform.

Correction: Covalent organic nanosheets for bioimaging

Correction for ‘Covalent organic nanosheets for bioimaging’ by Gobinda Das et al., Chem. Sci., 2018, DOI: ; 10.1039/c8sc02842g.

Zinc-Supported Multiwalled Carbon Nanotube Nanocomposite: A Synergism to Micronutrient Release and a Smart Distributor To Promote the Growth of Onion Seeds in Arid Conditions

In the current scenario, nanotechnological applications in the agriculture sector showing potential impacts on the improvement of plant growth in terms of protection and safety are at a very nascent stage. The present study deals with the synergistic role of zinc (Zn) and multiwalled carbon nanotubes (MWCNTs) synthesized as a zinc oxide (ZnO)/MWCNT nanocomposite, a prospective applicant to modulate the micronutrient supply and enhance the growth of onion seeds, thereby replacing harmful, unsafe chemical fertilizers. To the best of our knowledge, this is the first report wherein MWCNTs have been envisaged as a micronutrient distributor and a nutrient stabilizer enhancing the growth of onion plant under arid conditions. The growth trend of onion seeds was evaluated in an aqueous medium with varied concentrations of (i) MWCNTs, (ii) zinc oxide nanoparticles, and (iii) ZnO/MWCNT nanocomposites. ZnO/MWCNT nanocomposites with 15 μg/mL concentration displayed the best seedling growth with the maximum number of cells in telophase. A significant growth trend with increased concentration of ZnO/MWCNTs displayed no negative impact on plant growth in contrast to that with the use of MWCNTs. The synergistic impact of Zn nanoparticles and MWCNTs in ZnO/MWCNT nanocomposites on the rate of germination was explained via a mechanism supported by scanning transmission electron microscopy.

Author Correction: Physico-chemical properties based differential toxicity of graphene oxide/reduced graphene oxide in human lung cells mediated through oxidative stress

A correction has been published and is appended to both the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Covalent organic nanosheets for bioimaging

Non-toxic covalent organic nanosheet-based fluorescent nuclear stains.

Covalent organic nanosheets (CONs) have attracted much attention because of their excellent physical, chemical, electronic, and optical properties. Although covalent organic nanosheets have widely been used in many applications, there are only a few CONs that have been tested for bio-medical applications. Nanometer sized triazine-based nanosheets were obtained by exfoliating their bulk counterparts in water. The obtained nanosheets were dispersible and stable in water with enhanced photoluminescence properties compared to the bulk material. The nanosheets were biocompatible and non-toxic and showed ability to stain HeLa cell nuclei without additional assistance of an external targeting agent.

Encapsulation of Plant Viral Particles in Calcite Crystals

The concept of biomineralization and encapsulation of organic molecules into inorganic matrices to alter and enhance their physical properties has been evolved and perfected in natural systems. Being inspired by the natural biomineralization of foreign components into calcite, here the inclusion of a plant virus, cowpea mosaic virus (CPMV) of 5.4% by mass into crystals of calcite is reported. The viral particles are labeled with a fluorescent tag (Alexa Fluor 532), and are observed within the calcite matrix using confocal fluorescence microscopy. Upon encapsulation, the calcite crystals exhibit an irregular and aggregated morphology, as visualized with atomic force and electron microscopy. The viral particles protected inside the calcite crystals are able to resist harsh chemical agents. While spherical viral particles such as CPMV can be easily included in calcite, viruses such as the tobacco mosaic virus are not compatible with the host, presumably due to their high aspect ratio. The results provide a simple and scalable method to incorporate viral particles into inorganic matrix, and could prove useful in thermal stabilization of sensitive viral biological agents such as vaccines in the future.

Dual photoluminescence and charge transport in an alkoxy biphenyl benzoate ferroelectric liquid crystalline–graphene oxide composite

GO has been dispersed in a ferroelectric liquid crystalline material to prepare a FLC–GO composite.

Sequential Delivery of Doxorubicin and Zoledronic Acid to Breast Cancer Cells by CB[7]-Modified Iron Oxide Nanoparticles

Drug-loaded magnetic nanoparticles were synthesized and used for the sequential delivery of the antiresorptive agent zoledronic acid (Zol) and the cytotoxic drug doxorubicin (Dox) to breast cancer cells (MCF-7). Zol was attached to bare iron oxide nanoparticles (IONPs) via phosphonate coordination to form Z-NPs. The unbound imidazole of Zol was then used to complex the organic macrocycle CB[7] to obtain CZ-NPs. Dox was complexed to the CZ-NPs to form the fully loaded particles (DCZ-NPs), which were stable in solution at 37 °C and physiological pH (7.4). Fluorescence spectroscopy established that Dox is released in solution from DCZ-NPs suddenly (i) when the particles are subjected to magnetically induced heating to 42 °C at low pH (5.0) and (ii) in the presence of glutathione (GSH). Mass spectrometry indicated that Zol is released slowly in solution at low pH after Dox release. Magnetic measurements with a magnetic reader revealed that DCZ-NPs are internalized preferentially by MCF-7 cells versus nonmalignant cells (HEK293). Zol and Dox acted synergistically when delivered by the particles. DCZ-NPs caused a decrease in the viability of MCF-7 cells that was greater than the net decrease caused when the drugs were added to the cells individually at concentrations equivalent to those delivered by the particles. MCF-7 cells were treated with DCZ-NPs and subjected to an alternating magnetic field (AMF) which, with the nanoparticles present, raised the temperature of the cells and triggered the intracellular release of Dox, as indicated by fluorescence activated cell sorting (FACS). The cytotoxic effects of the DCZ-NPs on MCF-7 cells were enhanced 10-fold by AMF-induced heating. DCZ-NPs were also able to completely inhibit MCF-7 cell adhesion and invasion in vitro, indicating the potential of the particles to act as antimetastatic agents. Together these results demonstrate that DCZ-NPs warrant development as a system for combined chemo- and thermo-therapeutic treatment of cancer.

Cytoplasmic poly (A)-binding protein critically regulates epidermal maintenance and turnover in the planarian Schmidtea mediterranea

Identifying key cellular events that facilitate stem cell function and tissue organization is crucial for understanding the process of regeneration. Planarians are powerful model system to study regeneration and stem cell (neoblast) function. Here, using planaria, we show that the initial events of regeneration, such as epithelialization and epidermal organization are critically regulated by a novel cytoplasmic poly A-binding protein, SMED-PABPC2. Knockdown of smed-pabpc2 leads to defects in epidermal lineage specification, disorganization of epidermis and ECM, and deregulated wound healing, resulting in the selective failure of neoblast proliferation near the wound region. Polysome profiling suggests that epidermal lineage transcripts, including zfp-1, are translationally regulated by SMED-PABPC2. Together, our results uncover a novel role for SMED-PABPC2 in the maintenance of epidermal and ECM integrity, critical for wound healing and subsequent processes for regeneration.

Effect of graphene oxide interlayer electron-phonon coupling on the electro-optical parameters of a ferroelectric liquid crystal

Electro-optical properties of FLC are cell thickness dependent. Interlayer electron-phonon coupling is responsible for the change in the E-O properties. The FLC–GO composite is suitable for use in UV filters.

Phospholipase D activity couples plasma membrane endocytosis with retromer dependent recycling

During illumination, the light-sensitive plasma membrane (rhabdomere) of Drosophila photoreceptors undergoes turnover with consequent changes in size and composition. However, the mechanism by which illumination is coupled to rhabdomere turnover remains unclear. We find that photoreceptors contain a light-dependent phospholipase D (PLD) activity. During illumination, loss of PLD resulted in an enhanced reduction in rhabdomere size, accumulation of Rab7 positive, rhodopsin1-containing vesicles (RLVs) in the cell body and reduced rhodopsin protein. These phenotypes were associated with reduced levels of phosphatidic acid, the product of PLD activity and were rescued by reconstitution with catalytically active PLD. In wild-type photoreceptors, during illumination, enhanced PLD activity was sufficient to clear RLVs from the cell body by a process dependent on Arf1-GTP levels and retromer complex function. Thus, during illumination, PLD activity couples endocytosis of RLVs with their recycling to the plasma membrane thus maintaining plasma membrane size and composition.

DOI:http://dx.doi.org/10.7554/eLife.18515.001

Certain cells in the eye contain a receptor protein known as rhodopsin that enables them to detect light. Rhodopsin is found in distinct patches on the membrane surrounding each of these “photoreceptor” cells and the number of rhodopsin molecules present controls how sensitive the cell is to light. In humans, vitamin A deficiency or genetic defects can decrease the number of rhodopsin molecules on the membrane, leading to difficulty in seeing in dim light.

Fruit fly eyes also contain rhodopsin. Exposure to normal levels of light triggers parts of the membranes of fly photoreceptor cells to detach and move into the interior of the cell. These internalized pieces of membrane have two possible fates: they can either be destroyed or recycled back to the cell surface. This membrane turnover adjusts the size of the membrane surrounding the cell and the number of rhodopsin molecules in it to regulate the cell’s sensitivity to light. It is crucial that turnover is tightly regulated in order to maintain the integrity of the cell membrane. However, it is not clear how the process is regulated during light exposure.

Thakur et al. set out to address this question in fruit flies. The experiments show that an enzyme called phospholipase D is activated when photoreceptors are exposed to light. Active phospholipase D – which generates a molecule called phosphatidic acid – coordinates the internalization of pieces of membrane with the recycling of rhodopsin back to the cell surface. Thakur et al. generated fly mutants that lacked phospholipase D and in these animals the internalized rhodopsin was not transported back to the cell membrane. This caused the membrane to shrink in size and decreased the number of rhodopsin molecules in it. As a result, the photoreceptor cells became less sensitive to light.

The findings of Thakur et al. show that in response to normal levels of light, phospholipase D balances membrane internalization and recycling to maintain the size and rhodopsin composition of the membrane. Future challenges will be to work out exactly how phospholipase D is activated and how phosphatidic acid tunes membrane internalization and recycling.

DOI:http://dx.doi.org/10.7554/eLife.18515.002

Thermal deoxygenation causes photoluminescence shift from UV to blue region in lyophilized graphene oxide

Lyophilized graphene oxide (GO) was thermally exfoliated in stages at predefined temperatures up to 400 °C and the photoluminescence (PL) study of GO and thermally reduced GO (TGO) was carried out at each step.

Sequential therapy (triple drug-based induction chemotherapy followed by concurrent chemoradiotherapy) in locally advanced inoperable head and neck cancer patients - Single institute experience

Context:

India has a high incidence of head and neck squamous cell carcinoma (HNSCC) mostly presenting in advanced stage. In the majority of inoperable patients a combination of chemotherapy and radiotherapy (CRT) is considered as the treatment of choice. Adding induction chemotherapy (ICT) before CRT has shown to decrease systemic relapse. Incorporation of taxanes to the cisplatin and 5-FU-based ICT has shown increase in response rates.

Aims:

To evaluate the efficacy and toxicity of triple drug-based ICT followed by CCRT in locally advanced, inoperable HNSCC in the Indian context.

Settings and Design:

Prospective, non-controlled, observational study, a single-institute experience.

Materials and Methods:

Consecutive, locally advanced inoperable HNSCC patients were put on sequential therapy consisting of docetaxel, 5-FU and cisplatin for three cycles followed by concurrent weekly cisplatin and radiotherapy for responding or stable disease patients.

Results:

Forty-four patients were enrolled with male,female ratio of 33/44(75%) and 11/44(25%). Hypopharynx 16/44(36.36%) was the most common site followed by oral cavity 12/44(27.27%) and oropharynx 12/44(27.27%); 38/44(86.36%) patients could complete the planned treatment. Seven patients required dose reduction in ICT. As per the RECIST criteria, 16 patients had Complete Response (CR) and 15 had partial response (PR), 10 had stable disease (SD) and three had progressive disease (PD) after ICT. Thirty-eight patients received concomitant chemo radiotherapy (CCRT); 28/44 (66.63%) patients achieved CR, 10/44 (22.72 %) had PR. The main toxicity was mucositis 18/44 (40.90%) secondary to ICT. Grade III and IV hematological toxicity was seen in 16/44(36.36%), of which 6/44 (13.63%) had febrile neutropenia.

Conclusions:

Triple drug-based sequential therapy is tolerable in our context. In this trial from a single institute the results are very encouraging.

Antimicrobial activity of zirconia (ZrO2) nanoparticles and zirconium complexes

The antimicrobial activities of zirconia (ZrO2) nanoparticles and zirconium mixed ligand complexes were studied on bacterial strains of E. coli, S. aureus and fungal strain of A. niger. The nanoparticles of zirconia and Zr(IV) complexes with different amino acids as ligands were synthesized by hydrothermal method. X-ray diffraction (XRD) and HRTEM confirmed the crystalline nature and morphology of the synthesized products. The antimicrobial studies revealed that the zirconia exhibits activity only against the E. coli, whereas, the Zr(IV) complexes exhibits activity against both the bacteria: gram -ve E. coli and gram +ve S. aureus as well as fungal strains. The Zr(IV) complexes are found to possess significant antifungal activity against A. niger. The results are indicative of crystal plane-dependent antimicrobial activity of zirconia nanoparticles and complexes. The observed difference in the antibacterial activity of ZrO2 crystals and Zr(IV) complexes may be ascribed to the atomic arrangements of different exposed surfaces. On the basis of the study, it could be speculated that the ZrO2 nanoparticles with the same surface areas but with different shapes i.e., different active facets will show different antimicrobial activity.

Comparative study of leaching of silver nanoparticles from fabric and effective effluent treatment

Nano silver (Ag(n)) is employed as an active antimicrobial agent, but the environmental impact of Ag(n) released from commercial products is unknown. The quantity of nanomaterial released from consumer products during use should be determined to assess the environmental risks of advancement of nanotechnology. This work investigated the amount of silver released from three different types of fabric into water during washing. Three different types of fabric were loaded with chemically synthesized Ag nanoparticles and washed repeatedly under simulated washing conditions. Variable leaching rates among fabric types suggest that the manufacturing process may control the release of silver reaching the waste water treatment plants. In an attempt to recover the Ag(n) for reutilization and to save it from polluting water, the effluents from the wash were efficiently treated with bacterial strains. This treatment was based on biosorption and was very efficient for the elimination of silver nanoparticles in the wash water. The process ensured the recovery of the Ag(n) leached into the effluent for reutilization, thus preventing environmental repercussions.

Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging

A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.

Fabrication of Al-matrix composites reinforced with amino functionalized boron nitride nanotubes

Amino functionalized boron nitride nanotubes were used as the reinforcement material for the fabrication of Al-matrix composites using powder metallurgy process. It was found that the mechanical properties of these composites were improved significantly as compared to pure Al composites fabricated under similar conditions. The microhardness of these composites was found to improve by five times and compressive strength by 300% as compared to pure Al composites under similar processing conditions. The enhanced mechanical properties of these composites can be attributed to the proper dispersion of boron nitride nanotubes (BNNTs) in Al matrix and the formation of a strong interfacial bonding between BNNTs and Al matrix under the processing conditions. High-resolution transmission electron microscopy studies revealed the formation of transition layer of AlB2 which might lead to a better load transfer from Al matrix to the BNNTs. Further, these composites are believed to withstand high temperatures as compared to Al matrix composites reinforced with carbon nanotubes and, therefore, can be used for applications where lightweight and high strength materials are desired with stability at elevated temperatures.

Toxicity of graphene in normal human lung cells (BEAS-2B)

Graphite nanomaterials such as thermally exfoliated graphite oxide (GO) are versatile in many applications. However, little is known about its effects on biological systems. In this study we characrerized the GO using dynamic light scattering (DLS) along with the toxicological aspects related to cytotoxicity and apoptosis in normal human lung cells (BEAS-2B). A significant concentration and time dependent decrease in cell viability was observed at different concentrations (10-100 microg/ml) by the MTT assay after 24 and 48 h of exposure and significant increase of early and late apoptotic cells was observed as compared to control cells. Our study demonstrates that GO induces cytotoxicity and apoptosis in human lung cells.

HRTEM characterization in environmental risk assessment of engineered nanoparticles

For the purpose of assessing the risk of nanoparticles or of the products incorporating them, it is important to specify clearly the physical and chemical properties of these nanoparticles or products. High resolution transmission electron microscopy (HRTEM) offers the unique ability to observe nanoparticles (or any solid material) directly in real space at or close to the atomic scale, i.e., the scale at which they are ultimately defined. With modern HRTEM instruments, lattice or structure images of very small crystals (crystallites) or very small regions in larger crystals can be obtained with 0.2-0.3 nm (2-3 angstroms) resolution (less than 0.2 nm with dedicated intermediate--or high-voltage HRTEM instruments). No general conclusions applicable to all nanoparticle-based products are possible regarding the risks. Therefore, each product and process involving nanoparticles must be considered separately.

Porous anisotropic metal nanostructures through controlled transmetallation across a dialysis membrane

Nanostructured metals with hollow interiors are of technological importance due to their unique optoelectronic properties and enhanced surface area. We describe herein, a novel method for the synthesis of anisotropic gold and palladium nanoparticles through a simple galvanic replacement reaction across a semi-permeable dialysis membrane. The control over the reaction kinetics achieved by the presence of membrane enables one to tune the bimetal composition, particle porosity and morphology. Rapid outward diffusion of silver ions generated from the sacrificial silver nanoparticles even at room temperatures prevents the precipitation of high quantities of silver chloride, thereby circumventing the need for product purification. The porous anisotropic nanostructures have potential applications in catalysis, cell imaging and therapeutics.

Synthesis of catalytically active porous platinum nanoparticles by transmetallation reaction and proposition of the mechanism

A facile method for the synthesis of porous platinum nanoparticles by transmetallation reactions between sacrificial nickel nanoparticles and chloroplatinic acid (H(2)PtCl(6)) in solution, as well as at the constrained environment of the air-water interface, using a Langmuir-Blodgett instrumental setup is presented. To carry out the transmetallation at the air-water interface hydrophobized nickel nanoparticles are assembled as a monolayer on the sub phase containing platinum ions. The porous Pt nanoparticles obtained as a result of the reaction are found to act as extremely good catalysts for hydrogenation reaction. The products are well characterized by TEM, HRTEM, EDAX, and STEM. Attempts are made to postulate the plausible mechanism of this reaction to generate this kind of nanoparticle with controllable geometric shape and structure. This simple strategy has the potential to synthesize other nanomaterials of interest too.

Low temperature synthesis of magnetite and maghemite nanoparticles

We report on the synthesis of iron oxide nanoparticles below 100 degrees C by a simple chemical protocol. The uniqueness of the method lies in the use of Ferrous ammonium sulphate (in conjugation with FeCl3) which helps maintain the stability of Fe2+ state in the reaction sequence thereby controlling the phase formation. Hexamine was added as the stabilizer. The nanoparticles synthesized at three different temperatures viz, 5 degrees, 27 degrees, and 95 degrees C are characterized by several techniques. Generally, when a mixture of Fe3+ and Fe2+ is added to sodium hydroxide, alpha-Fe2O3 (the anti-ferromagnetic phase) is formed after the dehydration process of the hydroxide. In our case however, the phases formed at all the three temperatures were found to be ferro (ferri) magnetic, implying modification of the formation chemistry due to the specifics of our method. The nanoparticles synthesized at the lowest temperature exhibit magnetite phase, while increase in growth temperature to 95 degrees C leads to the maghemite phase.