The influence of salt stress on stomatal conductance of bitter cucumber (Momordica charantia L.)

Among the environmental stressors salinity is the main factor that calls into question the future of plant cultivation, be it agriculture, ornamental or medicinal plants. It currently affects almost a billion hectares of lands, of which 77 million hectares represent arable land. The intensification of stomatal conductance is directly correlated with the mechanical force involved in the opening of the stomata, which is influenced by the osmotic absorption of water, but also by the increase in hydrostatic pressure in the stomatal. This research was carried out in order to determine the bitter cucumber varieties with good resistance to salt stress. The materials used were represented by five varieties of bitter cucumber (Momordica charantia) of which: two Romanian varieties (Rodeo variety and Brâncusi variety) and three lines (Line 1, Line 3 and Line 4). The five varieties of bitter cucumber were subjected to salt stress for a 30 days period, during which they were constantly treated with saline solutions consisting of 100 mM and 200 mM concentration. Stomatal conductance was measured with SC-1 Leaf Porometer. The device is used to determine the flow of water vapor in and out of leaf stomata by inducing stomatal conductance

The Influence of Salt Stress on the Content of Vitamin C in the Leaves of some Varieties and Lines of Bitter Cucumber (Momordica charantia)

Bitter cucumber is a tropical and subtropical plant with a long history of medicinal use. Soil salinity is a major abiotic stress that affects the morphology and physiology of plants leading to reduced growth, production yield or in some cases their death. Salt stress increases the accumulation of reactive oxygen species in plants. They developed adaptation mechanisms by increasing the level of antioxidants, including vitamin C. The aim was to estimate the amount of vitamin C in the studied plants to determine the ability to adapt to salinity and improve nutritional properties. To carry out the experiment, two varieties and three experimental lines of bitter cucumber subjected to saline stress through treatments with saline solutions of different concentrations were used. The estimation of vitamin C content was carried out by UV-Vis spectrophotometry using the calibration curve method with standard L-ascorbic acid and KMnO4. After performing the analysis of variance on the varieties and lines of bitter cucumber, subjected to salt stress by applying the two treatments, it was found that the accumulation of vitamin C was insignificantly influenced by the factor a-the number of the treatment, but it was significantly influenced by the factor b-the concentration saline solution

Novel theranostic nanoporphyrins for photodynamic diagnosis and trimodal therapy for bladder cancer

The overall prognosis of bladder cancer has not been improved over the last 30 years and therefore, there is a great medical need to develop novel diagnosis and therapy approaches for bladder cancer. We developed a multifunctional nanoporphyrin platform that was coated with a bladder cancer-specific ligand named PLZ4. PLZ4-nanoporphyrin (PNP) integrates photodynamic diagnosis, image-guided photodynamic therapy, photothermal therapy and targeted chemotherapy in a single procedure. PNPs are spherical, relatively small (around 23 nm), and have the ability to preferably emit fluorescence/heat/reactive oxygen species upon illumination with near infrared light. Doxorubicin (DOX) loaded PNPs possess slower drug release and dramatically longer systemic circulation time compared to free DOX. The fluorescence signal of PNPs efficiently and selectively increased in bladder cancer cells but not normal urothelial cells in vitro and in an orthotopic patient derived bladder cancer xenograft (PDX) models, indicating their great potential for photodynamic diagnosis. Photodynamic therapy with PNPs was significantly more potent than 5-aminolevulinic acid, and eliminated orthotopic PDX bladder cancers after intravesical treatment. Image-guided photodynamic and photothermal therapies synergized with targeted chemotherapy of DOX and significantly prolonged overall survival of mice carrying PDXs. In conclusion, this uniquely engineered targeting PNP selectively targeted tumor cells for photodynamic diagnosis, and served as effective triple-modality (photodynamic/photothermal/chemo) therapeutic agents against bladder cancers. This platform can be easily adapted to individualized medicine in a clinical setting and has tremendous potential to improve the management of bladder cancer in the clinic

Nouvelles stratégies d élaboration des brosses polymères impliquant la "click chemistry"

Les travaux réalisés au cours de cette thèse concernent le développement d une méthode universelle de greffage de brosses polymères sur des substrats de silicium. Nous avons mis au point une telle méthode basée sur la click chemistry, permettant le greffage d une grande variété de structures sur de wafers de silicium. Dans un premier temps, nous avons étudié le greffage par click chemistry de trois types de polymère fonctionnalisés azoture: le PS, le PMMA et le PEG (de masses molaires similaires), sur des substrats fonctionnalisés par des alcynes. Les résultats montrent que la nature chimique du polymère n influence pas (ou peu) la réaction de greffage par click chemistry. Cependant, la concentration du polymère dans la solution du greffage, ainsi que la durée de la réaction de greffage jouent un rôle important sur la densité de greffage de brosses. Dans un second temps, le greffage des brosses de PEG de masses molaires variées par click chemistry sur substrat de silicium a permis l étude détaillée des différents paramètres tels que le temps de réaction, la concentration et la masse molaire du polymère. D une manière générale la densité de greffage augmente avec le temps de réaction et la concentration du polymère. Toutefois il y a une concentration critique (de chevauchement) à partir de la quelle la densité de greffage reste constante. L étude de l influence de la masse molaire du polymère sur la densité de greffage a montré que les petites masses conduisent à des grandes densités de greffage (1.2 chaînes/nm2) tandis que les grandes masses ne dépassent pas 0.08 chaînes/nm2. Ceci est lié au phénomène de diffusion de chaînes de la solution vers les sites actifs du substrat, qui est d autant plus marqué que la masse molaire de polymère est grande. Les brosses ont été caractérisées par ellipsométrie (déterminer l épaisseur), microscopie à force atomique (déterminer la morphologie des brosses) et la mouillabilité (déterminer la nature hydrophile ou hydrophobe des brosses)This thesis focuses on the development on a new, universal grafting method of polymer brushes to silicon wafers. We present herein a versatile and tunable grafting to approach based on click chemistry allowing the grafting of a wide range of chemical structures to silicon wafers. First we studied the grafting of three different azide-functionalized polymers: PS, PMMA and PEG with similar molecular weighs, to alkyne passivated silicon wafers via a click chemistry reaction. The results clearly showed that click chemistry grafting reaction is not affected by the chemical nature of the brush precursor and proceeds under mild and easy conditions. However, the polymer concentration in the reaction bath as well as the reaction time plays an important roll on the grafting density of the brushes. Second, the grafting of PEG brushes of different molecular masses on to silicon wafer via click chemistry was studied. The influence of different parameters as polymer molecular mass, polymer concentration in the grafting bath and the reaction time was studied. Generally, the grafting density increase when the reaction time and the polymer concentration are increased. There is a critical concentration (of overlapping) from which the grafting density remains constant. The study of the influence of polymer molecular weight on the brush grafting density showed that polymers with small weights give high grafting densities (1.2chains/nm2) while polymers with high molecular weighs do not exceed 0.08 chains/nm2. This is caused by the diffusion phenomenon of the polymer chains from solution to reach the active sites on the surface. This phenomenon is more important when grafting polymers with high molecular weights. The polymer brushes studied herein were characterized by ellipsometry (thickness), atomic force microscopy (morphology) and wetting (hydrophilic/ hydrophobic nature of brushes)LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Versatile approach for grafting polymer brushes to « passivated » silicon substrates using click chemistry

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