Electrically pumped continuous-wave O-band quantum-dot superluminescent diode on silicon.

High-power, broadband quantum-dot (QD) superluminescent diodes (SLDs) are ideal light sources for optical coherence tomography (OCT) imaging systems but have previously mainly been fabricated on native GaAs- or InP-based substrates. Recently, significant progress has been made to emigrate QD SLDs from native substrates to silicon substrates. Here, we demonstrate electrically pumped continuous-wave InAs QD SLDs monolithically grown on silicon substrates with significantly improved performance thanks to the achievement of a low density of defects in the III-V epilayers. The fabricated narrow-ridge-waveguide device exhibits a maximum 3 dB bandwidth of 103 nm emission spectrum centered at the O-band together with a maximum single facet output power of 3.8 mW at room temperature. The silicon-based SLD has been assessed for application in an OCT system. Under optimized conditions, a predicted axial resolution of ∼5.3µm is achieved with a corresponding output power of 0.66 mW/facet.

Electrically pumped continuous-wave 1.3 µm InAs/GaAs quantum dot lasers monolithically grown on on-axis Si (001) substrates.

We report on the first electrically pumped continuous-wave (cw) InAs/GaAs quantum dot (QD) lasers monolithically grown on on-axis Si (001) substrates without any intermediate buffer layers. A 400 nm antiphase boundary (APB) free epitaxial GaAs film with a small root-mean-square (RMS) surface roughness of 0.86 nm was first deposited on a 300 mm standard industry-compatible on-axis Si (001) substrate by metal-organic chemical vapor deposition (MOCVD). The QD laser structure was then grown on this APB-free GaAs/Si (001) virtual substrate by molecular beam epitaxy (MBE). Room-temperature cw lasing at ~1.3 µm has been achieved with a threshold current density of 425 A/cm2 and single facet output power of 43 mW. Under pulsed operation, lasing operation up to 102 °C has been realized, with a threshold current density of 250 A/cm2 and single facet output power exceeding 130 mW at room temperature.

Heat-sink free CW operation of injection microdisk lasers grown on Si substrate with emission wavelength beyond 1.3 µm.

High-performance injection microdisk (MD) lasers grown on Si substrate are demonstrated for the first time, to the best of our knowledge. Continuous-wave (CW) lasing in microlasers with diameters from 14 to 30 µm is achieved at room temperature. The minimal threshold current density of 600 A/cm2 (room temperature, CW regime, heatsink-free uncooled operation) is comparable to that of high-quality MD lasers on GaAs substrates. Microlasers on silicon emit in the wavelength range of 1320-1350 nm via the ground state transition of InAs/InGaAs/GaAs quantum dots. The high stability of the lasing wavelength (dλ/dI=0.1 nm/mA) and the low specific thermal resistance of 4×10-3°C×cm2/W are demonstrated.

Discovery of novel reversible inhibitor of DprE1 based on benzomorpholine for the treatment of tuberculosis.

About a quarter of the world's population is infected with Mycobacterium tuberculosis, equivalent to about two billion people. With the emergence of multidrug-resistant tuberculosis, those existing anti-tuberculosis drugs no longer meet the demand for cure anymore; there is an urgent need for the development of new anti-tuberculosis drugs. Decaprenylphosphoryl-ß-D-ribose 2´-epimerase (DprE1) has been proven to be a potential antimycobacterial target, and several inhibitors have entered clinical trial. Herein, we designed and synthesized a series of compounds based on the indole and benzomorpholine by using the strategy of scaffold hopping. The preferred compound B18 showed strong antimycobacterial activity in H37Rv and drug-resistant clinical isolates. In addition, compound B18 did not exhibit antimycobacterial efficacy against other species of strains. Subsequently, the target of B18 was identified as DprE1 by analyzing spontaneous compound-resistant mutation data, and a docking study was performed to illustrate the binding mode between B18 and DprE1. In general, compound B18 is compatible to current DprE1 inhibitors, even higher phosphodiesterase 6C selectivity and plasma protein binding rate, which represent a new type of effective reversible DprE1 inhibitor. IMPORTANCE Drug therapy remains the cornerstone of tuberculosis (TB) treatment, yet first-line anti-tuberculosis drugs are associated with significant adverse effects that can compromise patient outcomes. Moreover, prolonged and widespread use has led to an alarming rise in drug-resistant strains of Mycobacterium tuberculosis, including multidrug-resistant [MDR-tuberculosis (TB)] and extensively drug-resistant (XDR-TB) forms. Urgent action is needed to develop novel anti-tuberculosis agents capable of overcoming these challenges. We report that compound B18, a decaprenylphosphoryl-ß-D-ribose 2´-epimerase inhibitor with a benzomorpholine backbone, exhibits potent activity against not only the non-pathogenic strain H37Ra, but also the pathogenic strain H37Rv and clinical MDR and XDR strains. Preliminary druggability studies indicate that B18 possesses high safety and acceptable pharmacokinetic properties, rendering it a promising candidate for further development as a novel anti-tuberculosis agent.

Repurposed antipsychotic chlorpromazine inhibits colorectal cancer and pulmonary metastasis by inducing G2/M cell cycle arrest, apoptosis, and autophagy.

PURPOSE: Despite efforts in developing effective therapeutic strategies, colorectal cancer (CRC) remains one of the most prevalent and lethal neoplasms. Repurposing approved drugs is an alluring strategy for developing anticancer agents. Some antipsychotic drugs, including chlorpromazine (CPZ), possess anticancer activities. However, the pharmacological effects of CPZ on CRC have not been clearly established. METHODS: MTT assay, flow cytometry, western blotting analysis, subcutaneous mice tumor, and tail-vein-injection established lung metastasis model were used to investigate the anticancer effects of CPZ on CRC and the underlying mechanism. RESULTS: We found that CPZ effectively suppressed CRC by inducing G2/M cell cycle arrest and apoptosis. Cell cycle arrest was associated with decreased activities of the cdc2/cyclin B1 complex, including suppressed expression of cyclin B1, cdc2 and cdc25c, and elevated expression levels of phosphorylated cdc2 (Tyr15). Moreover, CPZ suppressed mitochondrial membrane potential and elevated reactive oxygen species levels in cancer cells, implying that it induces mitochondria-dependent intrinsic apoptosis. CPZ blocked the autophagic flux and induced cytotoxic autophagy in CRC cells. In addition, CPZ suppressed tumor growth in two subcutaneous mouse models without causing obvious side effects. Analysis of the abundance of immune cells in the tumor microenvironment revealed that CPZ did not have an effect on their proportions. Furthermore, it significantly suppressed the lung metastasis of CT26 cells and prolonged mice survival. CONCLUSION: These findings indicated that repurposing CPZ is a novel treatment strategy for CRC patients.

OSW-1 induces apoptosis and cyto-protective autophagy, and synergizes with chemotherapy on triple negative breast cancer metastasis.

PURPOSE: Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer. As yet, chemotherapy with drugs such as doxorubicin is the main treatment strategy. However, drug resistance and dose-dependent toxicities restrict their clinical use. Natural products are major sources of anti-tumor drugs. OSW-1 is a natural compound with strong anti-cancer effects in several types of cancer, but its effects on the efficacy of chemotherapy in TNBC and its underlying mechanism remain unclear. METHODS: The inhibitory activities of OSW-1 and its combination with several chemotherapy drugs were tested using in vitro assays and in vivo subcutaneous and metastatic mouse TNBC models. The effects of the mono- and combination treatments on TNBC cell viability, apoptosis, autophagy and related signaling pathways were assessed using MTT, flow cytometry, RNA sequencing and immunology-based assays. In addition, the in vivo inhibitory effects of OSW-1 and (combined) chemotherapies were evaluated in subcutaneous and metastatic mouse tumor models. RESULTS: We found that OSW-1 induces Ca2+-dependent mitochondria-dependent intrinsic apoptosis and cyto-protective autophagy through the PI3K-Akt-mTOR pathway in TNBC cells in vitro. We also found that OSW-1 and doxorubicin exhibited strong synergistic anti-TNBC capabilities both in vivo and in vitro. Combination treatment strongly inhibited spontaneous and experimental lung metastases in 4T1 mouse models. In addition, the combination strategy of OSW-1 + Carboplatin + Docetaxel showed an excellent anti-metastatic effect in vivo. CONCLUSIONS: Our data revealed the mode of action and molecular mechanism underlying the effect of OSW-1 against TNBC, and provided a useful guidance for improving the sensitivity of TNBC cells to conventional chemotherapeutic drugs, which warrants further investigation.

Design, synthesis, and biological evaluation of benzo[b]thiophene 1,1-dioxide derivatives as potent STAT3 inhibitors.

As a member of the signal transducer and activator of transcription (STAT) family, STAT3 plays a critical role in several biological pathways such as cell proliferation, migration, survival, and differentiation. Due to abnormal continuous activation in tumors, inhibition of STAT3 has emerged as an attractive approach for the treatment of various cancer cells. Herein, we report a series of novel STAT3 inhibitors based on benzo[b]thiophene 1,1-dioxide scaffold and evaluated their anticancer potency. Among them, compound 8b exhibited the best activity against cancer cells. Compound 8b induced apoptosis and blocked the cell cycle. Meanwhile, 8b reduced intracellular ROS content and caused the loss of mitochondrial membrane potential. Further research revealed that 8b significantly blocked STAT3 phosphorylation and STAT3-dependent dual-luciferase reporter gene experiments showed that compound 8b has a marked inhibition of STAT3-mediated Firefly luciferase activity. Molecular modeling studies revealed compound 8b occupied the pocket well with the SH2 domain in a favorable conformation.

An overview of Sirtuins as potential therapeutic target: Structure, function and modulators.

Sirtuin (Yeast Silent Information RegulatorsⅡ, Sir2) was first discovered in the 1970s. Because of its function by removing acetylated groups from histones in the presence of nicotinamide adenine dinucleotide (NAD+), waves of research have assessed the potential of Sirtuin as a therapeutic target. The Sirtuin family, which is widely distributed throughout the nature, has been divided into seven human isoforms (Sirt1-Sirt7). They are thought to be closely related to some aging diseases such as cardiovascular disorders, neurodegeneration, and tumors. Herein, we present a comprehensive review of the structure, function and modulators of Sirtuins, which is expected to be beneficial to relevant studies.

Betulinic acid impairs metastasis and reduces immunosuppressive cells in breast cancer models.

Breast cancer is the most common female cancer with considerable metastatic potential, explaining the need for new candidates that inhibit tumor metastasis. In our study, betulinic acid (BA), a kind of pentacyclic triterpenoid compound derived from birch trees, was evaluated for its anti-metastasis activity in vitro and in vivo. BA decreased the viability of three breast cancer cell lines and markedly impaired cell migration and invasion. In addition, BA could inhibit the activation of stat3 and FAK which resulted in a reduction of matrix metalloproteinases (MMPs), and increase of the MMPs inhibitor (TIMP-2) expression. Moreover, in our animal experiment, intraperitoneal administration of 10 mg/kg/day BA suppressed 4T1 tumor growth and blocked formation of pulmonary metastases without obvious side effects. Furthermore, histological and immunohistochemical analyses showed a decrease in MMP-9 positive cells, MMP-2 positive cells and Ki-67 positive cells and an increase in cleaved caspase-3 positive cells upon BA administration. Notably, BA reduced the number of myeloid-derived suppressor cells (MDSCs) in the lungs and tumors. Interestingly, in our caudal vein model, BA also obviously suppressed 4T1 tumor pulmonary metastases. These findings suggested that BA might be a potential agent for inhibiting the growth and metastasis of breast cancer.

HPLC Determination of Enantiomeric Purity of Letermovir Based on CHIRALPAK AD.

A precise and sensitive LC method was developed and further validated for the determination of enantiomeric purity of {(4S)-8-Fluoro-2-[4-(3-methoxyphenyl)-1-piperazinyl]-3-[2-methoxy-5-(trifluoromethyl)phenyl]-3,4-dihydro-4-quinazolinyl} acetic acid (Letermovir). Baseline separation with a resolution >2.8 was accomplished within 10 min using a CHIRALPAK AD (250 mm × 4.6 mm; particle size 5 µm) column, with n-hexane/2-propanol (80:20 v/v) as mobile phase at a flow rate of 1 mL min-1. The eluted analytes were monitored by UV detection at 260 nm. The effects of mobile phase composition and temperature on enantiomeric selectivity as well as resolution of enantiomers were thoroughly investigated. The calibration curves were plotted within the concentration range between 0.003 and 1 mg mL-1 (n = 14), and the recoveries between 98.24 and 101.43% were obtained, with relative standard deviation <1.29%. The limit of detection (LOD) and limit of quantitation (LOQ) for Letermovir were 0.96 and 3.15 µg mL-1; those for its enantiomer were 1.01 and 3.39 µg mL-1, respectively. The developed method was demonstrated to be accurate, robust and sensitive for the determination of enantiomeric purity of Letermovir, especially for the analysis of bulk samples.