Self-pulsation at 480 GHz from a two-color discrete mode laser diode

A discrete mode Fabry-Pérot laser is designed and fabricated to achieve two-color lasing. We demonstrate beating between the two laser modes and self-pulsation at 480 GHz

Inverse scattering approach to multiwavelength Fabry-Pérot laser design

A class of multiwavelength Fabry-Pérot lasers is introduced where the spectrum is tailored through a patterning of the cavity effective index. The cavity geometry is obtained using an inverse scattering approach and can be designed such that the spacing of discrete Fabry-Pérot lasing modes is limited only by the bandwidth of the inverted gain medium. A specific two-color semiconductor laser with a mode spacing in the THz region is designed, and measurements are presented demonstrating the simultaneous oscillation of the two wavelengths. The nonperiodic effective index profile of the particular two-color device considered is shown to be related to a Moiré or superstructure grating

A method to estimate the efficiency of gene expression from an integrated retroviral vector

BACKGROUND: Proviral gene expression is a critical step in the retroviral life cycle and an important determinant in the efficiency of retrovirus based gene therapy vectors. There is as yet no method described that can assess the efficiency of proviral gene expression while vigorously excluding the contribution from unstable species such as passively transferred plasmid and LTR circles. Here, we present a method that can achieve this. RESULTS: Proviral gene expression was detected by the activity of the puromycin resistance gene encoded in the viral vector, and quantified by comparing the growth curve of the sample under puromycin selection to that of a series of calibration cultures. Reproducible estimates of the efficiency of proviral gene expression could be derived. We confirm that contamination from unstable species such as passively transferred plasmid used in viral vector production and unintegrated viral DNA can seriously confound estimates of the efficiency of transduction. This can be overcome using a PCR based on limiting dilution analysis. CONCLUSION: A simple, low cost method was developed that should be useful in studying the biology of retroviruses and for the development of expression systems for retrovirus based gene therapy

OLED-on-silicon for near-to-eye microdisplays and sensing

Smart eyewear featuring near-to-eye (NTE) displays have evolved as major devices for wearable displays, which hold potential to become adopted by consumers soon. Tiny OLED-on-silicon microdisplays (<1” screen diagonal) are a key component of eyewear displays, creating images from active-matrix organic light emitting diodes (AM-OLED), similar to those that have become popular in mobile phone displays

Quantification of lentiviral vector copy numbers in individual hematopoietic colony-forming cells shows vector dose-dependent effects on the frequency and level of transduction

Lentiviral vectors are effective tools for gene transfer and integrate variable numbers of proviral DNA copies in variable proportions of cells. The levels of transduction of a cellular population may therefore depend upon experimental parameters affecting the frequency and/or the distribution of vector integration events in this population. Such analysis would require measuring vector copy numbers (VCN) in individual cells. To evaluate the transduction of hematopoietic progenitor cells at the single-cell level, we measured VCN in individual colony-forming cell (CFC) units, using an adapted quantitative PCR (Q-PCR) method. The feasibility, reproducibility and sensitivity of this approach were tested with characterized cell lines carrying known numbers of vector integration. The method was validated by correlating data in CFC with gene expression or with calculated values, and was found to slightly underestimate VCN. In spite of this, such Q-PCR on CFC was useful to compare transduction levels with different infection protocols and different vectors. Increasing the vector concentration and re-iterating the infection were two different strategies that improved transduction by increasing the frequency of transduced progenitor cells. Repeated infection also augmented the number of integrated copies and the magnitude of this effect seemed to depend on the vector preparation. Thus, the distribution of VCN in hematopoietic colonies may depend upon experimental conditions including features of vectors. This should be carefully evaluated in the context of ex vivo hematopoietic gene therapy studies

GENE-CELL THERAPY OF HIV AND HEMATOLOGICAL MALIGNANCES BASED ON HEMATOPOIETIC STEM CELL TRANSPLANTATION AND SITE-SPECIFIC GENOME EDITING

Based on the annual UNAIDS reports the number of HIVinfected patients is continually growing since 1983. Antiretroviral Therapy (ART) allows to prolong life expectancy, but the problem of life quality and overall survival is still remaining. Nowadays, in the era of ART, one of the main cause of mortality in HIV-infected patients is malignancies. Lymphomas play one of the key roles in this group of diseases. The treatment of lymphomas includes combined regiments of chemotherapy with a curative potential. High dose chemotherapy with autologous hematopoietic stem cell transplant (auto-HSCT) is the main path of the treatment for relapsed / refractory lymphomas. In the last few years with a development of the genome editing technology auto-HSCT is becoming one of the most promising methods of HIV treatment. The case of “Berlin patient” when allogeneic HSCT from donor with mutation CCR5-delta32 lead to cure from HIV and proof of concept the efficacy of the gene therapy for HIV based on HSCT. Hematopoietic stem cell transplantation with edited autologous HSC (CCR5 knockout by site-specific genome editing tools with engineering nucleases) is a comprehensive treatment for this cohort of patients. On one hand, high dose chemotherapy with auto-HSCT cures the malignancy; on the other hand auto-HSCT works as a delivery method for the edited cells and creates an environment for the HIV eradication. This review is dedicated to HIV and oncology, methods of treatment of hematological malignancies and HIV-infection using genome editing technology based on HSCT

Avoiding cytotoxicity of transposases by dose-controlled mRNA delivery

The Sleeping Beauty (SB) transposase and its newly developed hyperactive variant, SB100X, are of increasing interest for genome modification in experimental models and gene therapy. The potential cytotoxicity of transposases requires careful assessment, considering that residual integration events of transposase expression vectors delivered by physicochemical transfection or episomal retroviral vectors may lead to permanent transposase expression and resulting uncontrollable transposition. Comparing retrovirus-based approaches for delivery of mRNA, episomal DNA or integrating DNA, we found that conventional SB transposase, SB100X and a newly developed codon-optimized SB100Xo may trigger premitotic arrest and apoptosis. Cell stress induced by continued SB overexpression was self-limiting due to the induction of cell death, which occurred even in the absence of a co-transfected transposable element. The cytotoxic effects of SB transposase were strictly dose dependent and heralded by induction of p53 and c-Jun. Inactivating mutations in SB’s catalytic domain could not abrogate cytotoxicity, suggesting a mechanism independent of DNA cleavage activity. An improved approach of retrovirus particle-mediated mRNA transfer allowed transient and dose-controlled expression of SB100X, supported efficient transposition and prevented cytotoxicity. Transposase-mediated gene transfer can thus be tuned to maintain high efficiency in the absence of overt cell damage

Universal high work function flexible anode for simplified ITO-free organic and perovskite light-emitting diodes with ultra-high efficiency

Flexible transparent electrode materials such as conducting polymers, silver nanowires, carbon nanotubes and graphenes are being investigated as possible replacements for conventional brittle inorganic electrodes. However, they have critical drawbacks of low work function (WF), resulting in a high hole injection barrier to an overlying semiconducting layer in simplified organic or organic-inorganic hybrid perovskite light-emitting diodes (OLEDs or PeLEDs). Here, we report a new anode material (AnoHIL) that has multifunction of both an anode and a hole injection layer (HIL) as a single layer. The AnoHIL has easy WF tunability up to 5.8 eV and thus makes ohmic contact without any HIL. We applied our anodes to simplified OLEDs, resulting in very high efficiency (62% ph el(-1) for single and 88% ph el(-1) for tandem). The AnoHIL showed a similar tendency in simplified PeLEDs, implying universal applicability to various optoelectronics. We also demonstrated large-area flexible lightings using our anodes. Our results provide a significant step toward the next generation of high-performance simplified indium tin oxide (ITO)-free light-emitting diodes.

An Efficient Vector System to Modify Cells Genetically

The transfer of foreign genes into mammalian cells has been essential for understanding the functions of genes and mechanisms of genetic diseases, for the production of coding proteins and for gene therapy applications. Currently, the identification and selection of cells that have received transferred genetic material can be accomplished by methods, including drug selection, reporter enzyme detection and GFP imaging. These methods may confer antibiotic resistance, or be disruptive, or require special equipment. In this study, we labeled genetically modified cells with a cell surface biotinylation tag by co-transfecting cells with BirA, a biotin ligase. The modified cells can be quickly isolated for downstream applications using a simple streptavidin bead method. This system can also be used to screen cells expressing two sets of genes from separate vectors