Developed cascaded multilevel inverter topology to minimise the number of circuit devices and voltage stresses of switches

In this study, a novel structure for cascade multilevel inverter is presented. The proposed inverter can generate all possible DC voltage levels with the value of positive and negative. The proposed structure results in reduction of switches number, relevant gate driver circuits and also the installation area and inverter cost. The suggested inverter can be used as symmetric and asymmetric structures. Comparing the peak inverse voltage and losses of the proposed inverter with conventional multilevel inverters show the superiority of the proposed converter. The operation and good performance of the proposed multilevel inverter have been verified by the simulation results of a single-phase nine-level symmetric and 17-level asymmetric multilevel inverter and experimental results of a nine-level and 17-level inverters. Simulation and experimental results confirmed the validity and effectiveness performance of the proposed inverter

Breathing Life into Polycations

The lack of efficient delivery systems is still limiting the full therapeutic potential of siRNA. For the purpose of nucleic acid transfer, among other synthetic carrier systems, polycations have been applied. Favorable characteristics of suitable polymers include nucleic acid binding, compaction, protection, and biocompatibility. However the lack of nucleic acid transfer activity in transfection-based screening often abandons promising candidates. Here we present that functionalization may turn polycations with poor delivery activity into efficient carriers:  for example, polylysine, on its own lacking nucleic acid transfer activity, displayed high efficiency in siRNA delivery after modification with polyethylene glycol and a pH-responsive endosomolytic peptide. Hence these findings have implication for the selection process of polymeric carriers for siRNA

Viral vector mimicking and nucleus targeted nanoparticles based on Dexamethasone conjugated Polyethylenimine nano-liposomes: Preparation and evaluation of transfection efficiency

Non-viral vectors such as polymers and liposomes have been used for gene delivery systems to overcome intrinsic problems of viral vectors, but transfection efficiency of these vectors is lower than viral vectors. In the present study, we conjugated dexamethasone (Dexa) to branched polyethylenimine (b-PEI), in combinations with cationic liposomes as a nonviral system to improve transfection efficiency. Cationic liposomes containing DOTAP and cholesterol were prepared by thin-film hydration following extrusion method. Dexamethasone mesylate was synthesized and conjugated to polyethylenimine by a one-step reaction. A novel gene delivery system, Lipopolyplex was developed by premixing liposome and different Mw of bPEI-Dexa as carriers following by addition of plasmid at three different C/P ratios. The resultant complexes were characterized for their size, zeta potential and ability of DNA condensation. Luciferase reporter gene was used for determination of transfection efficiency in neuro2A cells. Also, the toxicity of gene carriers was investigated in this cell line. Mean particle size of prepared complexes was less than 200 nm and there was no significant difference in size by increasing molecular weight of PEIs. All complexes had positive surface charge. Complete condensation of DNA was occurred at C/P ratio of 1 for all complexes. lipopolyplexes were more efficient than polyplexes and lipoplexes alone and transfection efficiency was improved by adding dexamethasone. Complexes containing liposome, PEI 10 kDa and dexamethasone had the highest transfection activity. Furthermore, non-viral vectors described in this study showed low cytotoxicity. The results of this study confirm that PEI in combination with liposome as lipopolyplex have low toxicity and may enhance transfection efficiency. Moreover, conjugation of dexamethasone to PEI, in combination with cationic liposome might be useful for the gene deliver

Recent Advances in Lung Cancer Therapy Based on Nanomaterials: A Review

Lung cancer is one of the commonest cancers with a significant mortality rate for both genders, particularly in men. Lung cancer is recognized as one of the leading causes of death worldwide, which threatens the lives of over 1.6 million people every day. Although cancer is the leading cause of death in industrialized countries, conventional an-ticancer medications are unlikely to increase patients' life expectancy and quality of life significantly. In recent years, there are significant advances in the development and applications of nanotechnology in cancer treatment. The superiority of nanostructured approaches is that they act more selectively than traditional agents. This progress led to the development of a novel field of cancer treatment known as nanomedicine. Various formulations based on nanocarriers, including lipids, polymers, liposomes, nanoparticles and dendrimers have opened new horizons in lung cancer therapy. The application and expan-sion of nano-agents lead to an exciting and challenging research era in pharmaceutical science, especially for the delivery of emerging anti-cancer agents. The objective of this review is to discuss the recent advances in three types of nanoparticle formulations for lung cancer treatments modalities, including liposomes, polymeric micelles, and den-drimers for efficient drug delivery. Afterward, we have summarized the promising clinical data on nanomaterials based therapeutic approaches in ongoing clinical studies

Cationic Liposomes Modified with Polyallylamine as a Gene Carrier: Preparation, Characterization and Transfection Efficiency Evaluation

Purpose: Cationic polymers and cationic liposomes have shown to be effective non-viral gene delivery vectors. In this study, we tried to improve the transfection efficiency by employing the advantages of both. Methods: For this purpose, modified polyallylamines (PAAs) were synthesized. These modifications were done through the reaction of PAA (15 KDa) with acrylate and 6-bromoalkanoic acid derivatives. Liposomes comprising of these cationic polymers and cationic lipid were prepared and extruded through polycarbonate filters to obtain desired size. Liposome-DNA nanocomplexes were prepared in three carrier to plasmid (C/P) ratios. Size, zeta potential and DNA condensation ability of each complex were characterized separately and finally transfection efficiency and cytotoxicity of prepared vectors were evaluated in Neuro2A cell line. Results: The results showed that mean particle size of all these nanocomplexes was lower than 266 nm with surface charge of 22.0 to 33.9 mV. Almost the same condensation pattern was observed in all vectors and complete condensation was occurred at C/P ratio of 1.5. The lipoplexes containing modified PAA 15 kDa with 10% hexyl acrylate showed the highest transfection efficacy and lowest cytotoxicity in C/P ratio of 0.5. Conclusion: In some cases nanocomplexes consisting of cationic liposome and modified PAA showed better transfection activity and lower cytotoxicity compared to PAA

A simple, sensitive and rapid isocratic reversed-phase high-performance liquid chromatography method for determination and stability study of curcumin in pharmaceutical samples

Objective: This study was designed to develop and validate a new reversed-phase high-performance liquid chromatography (RP-HPLC) method based on Q2 (R1) International Conference on Harmonization (ICH) guideline for determination of curcumin in pharmaceutical samples. Materials and Methods: The HPLC instrument method was optimized with isocratic elution with acetonitrile: ammonium acetate (45:55, v/v, pH 3.5), C18 column (150 mm×4.6 mm×5 µm particle size) and a flow rate of 1 ml/min in ambient condition and total retention time of 17 min. The volume of injection was set at 20 µl and detection was recorded at 425 nm. The robustness of the method was examined by changing the mobile phase composition, mobile phase pH, and flow rate. Results: The method was validated with respect to precision, accuracy and linearity in a concentration range of 2-100 µg/ml. The limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.5 µg/ml, respectively. The percentage of recovery was 98.9 to 100.5 with relative standard deviation (RSD) < 0.638%. Conclusion: The method was found to be simple, sensitive and rapid for determination of curcumin in pharmaceutical samples and had enough sensitivity to detect degradation product of curcumin produced under photolysis and hydrolysis stress condition

Curcumin improved liposomal mitomycin-induced cell toxicity in bladder cancer cell

Objective (s): This study aimed at investigation of preparation and stability study of Mitomycin and Mitomycin loaded nanoliposems and efficacy of the combination of Mitomycin -loaded nanoliposomes and Curcumin versus Mitomycin in suppressing HTB-9 and L929 cell lines, in vitro.Materials and Methods: An HPLC method was validated based on Q2 (R1) International Conference on Harmonization (ICH) guideline for determination of Mitomycin in pharmaceutical samples. Soybean phosphatidylcholine (SPC) or hydrogenated soybean phosphatidylcholine (HSPC) mixed with cholesterol at 2:1 molar ratio respectively in two different groups to prepare Mitomycin nanoliposomes. Cell toxicity of free Mitomycin, Mitomycin loaded liposomes and curcumin was measured using MTT assay in bladder cancer cell line for treatment group and Fibroblast-like cell as control group. Also, propidium iodide staining was done to determine the level of DNA fragmentation.Results: The validated HPLC method showed stability based on the ICH guideline (n=3 and RS

A new scheme of symmetric multilevel inverter with reduced number of circuit devices

In this paper, a sophisticated configuration for symmetric multilevel voltage source inverters is proposed. In multilevel inverters, the costs, circuit size so installation space, complexness of control scheme and reliability are directly depended to the amount of circuit devices required. The provided comparison study among proposed inverter, CHB and recently introduced converters, validates that the proposed inverter reduces the requirements for circuit devices, including power semi-conductor switches, IGBTs, diodes, gate driver circuits and DC voltage sources. The given simulation results confirms the feasibleness of the projected modular structure. Also, to approve the practicality of the proposed inverter, a prototype of the proposed topology has been implemented. Finally simulation and experimental results are compared with one another and therefore the provided comparison shows that the obtained results are in sensible agreements