Synthesis and evaluation of designed PKC modulators for enhanced cancer immunotherapy.

Bryostatin 1 is a marine natural product under investigation for HIV/AIDS eradication, the treatment of neurological disorders, and enhanced CAR T/NK cell immunotherapy. Despite its promising activity, bryostatin 1 is neither evolved nor optimized for the treatment of human disease. Here we report the design, synthesis, and biological evaluation of several close-in analogs of bryostatin 1. Using a function-oriented synthesis approach, we synthesize a series of bryostatin analogs designed to maintain affinity for bryostatin's target protein kinase C (PKC) while enabling exploration of their divergent biological functions. Our late-stage diversification strategy provides efficient access to a library of bryostatin analogs, which per our design retain affinity for PKC but exhibit variable PKC translocation kinetics. We further demonstrate that select analogs potently increase cell surface expression of CD22, a promising CAR T cell target for the treatment of leukemias, highlighting the clinical potential of bryostatin analogs for enhancing targeted immunotherapies

Asymmetric Dual Enamine Catalysis/Hydrogen Bonding Activation

Asymmetric enamine base activation of carbonyl compounds is a well-known and widely used strategy for providing functionalization of organic compounds in an efficient way. The use of solely organic substances, which in most cases are commercially available primary or secondary amines that are easy to obtain, avoids the use of hazardous substances or metal traces, making this type of catalysis a highly convenient methodology from a sustainable point of view. In many cases, the reactivity or the stereoselectivity obtained is far from being a practical and advantageous strategy; this can be improved by using a hydrogen bonding co-catalyst that can help during the activation of one species or by using a bifunctional catalyst that can direct the approximation of reagents during the reaction outcome. In this review, we describe the most efficient methodologies that make use of a dual activation of reagents for performing α-functionalization (enamine activation) or remote functionalization (such as dienamine or trienamine activation) of carbonyl compounds.PID2020-118422GB-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future” are gratefully acknowledged together with the Basque Government (Grupos IT1558-22) and the University of the Basque Country (UPV/EHU)

Tailoring the features of covalent organic frameworks

Covalent organic frameworks (COFs) represent a new and emerging class of functional materials built from organic subunits. These networks are formed via reversible co-condensation reactions resulting in covalent bonds based on diverse binding motifs. Due to the great variety and large number of accessible building blocks, structural and functional diversity can be achieved easily. By combining desired subunits, crystalline and porous two- or three-dimensional frameworks can be synthesized exhibiting a defined pore size and a high surface area. Crystallinity and porosity are of central importance for many characteristics of COFs such as adsorption, diffusion, and electronic transport. The possible role of COF materials applied for sensing, catalysis, and optoelectronic applications is based on their tunable characteristics which can be tailored by implementing suitable subunits. Furthermore, postsynthetic modifications can be used to adjust properties of the framework while maintaining the main aspects. In general, COFs can be synthesized during solvothermal reaction conditions followed by diverse work-up steps which have to be adapted and optimized for each system. Therefore, finding the right parameters is key for the successful synthesis of crystalline materials and mastering them enables the formation of thin films on suitable substrates. This is particularly important for device applications in the optoelectronic area. This thesis focuses on the synthesis of novel two-dimensional COFs, introducing new characteristic features into such frameworks. The different COF materials were fully characterized by various methods to ensure high crystallinity and porosity as well as elucidating their morphology and structure. Next to neat bulk and film materials, also full electronic devices were fabricated for further analysis. In addition, postsynthetic treatments concerning structural improvement and pore wall modifications were investigated. The possible applications arising from introducing additional functionality after the synthesis were a substantial part of this work. The experimental results of this thesis can be separated into three main parts: structural control as well as implementation of dyes and electroactive subunits, electrical characterization, and postsynthetic treatment methods. In general, while Chapter 1 of this thesis is introducing the main aspects of COFs and the theoretical background, Chapter 2 contains descriptions of the methods used for materials characterization. The first part of the experimental results (Chapter 3 and 4) deals with structural control including the implementation of dyes and the comparison of imine and boronate ester binding motifs. Chapter 3 is focused on the precise construction of template-free nano- and microstructures of dye-containing porous materials. The implemented organic dye diketopyrrolopyrrole was functionalized with accessible aldehyde groups. After reaction with a tetra amine-functionalized porphyrin building block the resulting DPP-TAPP-COF showed enhanced absorption capabilities. Regarding structural control, the obtained COF exhibited spontaneous aggregation into hollow microtubular assemblies with well-defined and controllable outer and inner tube diameters. A detailed mechanistic morphology investigation revealed that the whole process is time-dependent and undergoes a traceable transformation starting with sheet-like agglomerates into stable tubular microstructures via a rolling-up mechanism. As already mentioned in the third chapter (the implementation of sterically demanding dyes as building blocks for COF systems), the integration of diketopyrrolopyrrole molecules is still hampered by limited control of the binding motif in combination with the size of the backbone. In Chapter 4, the results of using a flat, rigid, and non-conjugated boronate ester bond combined with the dye and a suitable counterpart are reported. Here, structural control was achieved and led to enhanced properties and enforced specific stacking behavior. The COF was successfully synthesized and crystallinity as well as porosity could be improved as compared to the imine-connected counter-part, with even shorter reaction times. The boronate ester coupling motif guides the formation of a planar and rigid backbone and long-range molecular stacks. Furthermore, the COF exhibits application-relevant optical properties including strong absorption over the visible spectral range, broad emission into the near infrared region (NIR), and a long singlet lifetime. All the findings can be attributed to the controlled formation of molecular stacks with J-type interactions between the subcomponents in the COF. In addition, these molecular stacks showed an influence on the electronic behavior revealing electrical conductivity values of crystalline COF pellets up to 10 6 Scm-1. Further investigations on electrical conductivity and charge carrier mobility studies on different COF systems are described in Chapter 5. Here, a series of acene-based building blocks was implemented into a scaffold, i.e. benzene and anthracene dialdehyde-functionalized subunits, which show high charge carrier mobilities comparable to organic materials in single crystals. The building blocks were designed in a way to tailor the length of the resulting aromatic backbone pointing into the pore of the framework without changing the overall unit cell dimensions, i.e. the molecules were inserted perpendicular to the binding direction. This allows for a better comparison of the structures and the resulting properties. The measurements revealed that the length of the backbone has a strong influence on the achieved electrical conductivity and mobility values. Moreover, different measurement methods for conductivity in combination with mobility are compared due to the diverse theoretical backgrounds each method is based on, yielding technique-specific values. In addition, all COF samples revealed surprisingly high Hall mobility values for pressed powder pellets as well as for thin films and devices. The measured hole-only devices exhibited up to 10 3 cm2V-1s-1 for the anthracene COF, which is one of the largest values of intrinsic mobility for COFs so far. The results point towards the importance of π-overlap and hence the length of the acene unit. Further extension of the series towards the even longer pentacene unit was initiated but will be part of future studies. The third part of the experimental results deals with the different possibilities of postsynthetic treatments. In Chapter 6, a new postsynthetic treatment for covalent organic frameworks is introduced. Here, a newly synthesized anthracene-based COF (from Chapter 5) is reported followed by a postsynthetic treatment based on light-induced defect reduction. The applied laser light apparently leads to opening and reformation of imine bonds resulting in a significant decrease of defect sites and therefore a striking increase in photoluminescence. This effect was further supported by IR investigations showing a reduced intensity of aldehyde and amine vibrations and a gain of imine vibration intensity upon laser irradiation of a stoichiometric precursor mix. Another approach regarding postsynthetic treatment is presented in Chapter 7, based on chemical modification after successful COF synthesis. A novel terphenyldiboronic acid-based COF is reported which features accessible hydroxyl groups at the inner and outer pore wall environment. These functional groups serve as anchor sites for a fluorescence label which can be installed by a postsynthetic modification approach. By forming o thiocarbamate bonds, fluorescein molecules were immobilized on the inner as well as at the outer surface of the pore system. This reaction was further extended to another COF system and to other grafting moieties. In conclusion, this thesis mainly focused on the fundamental synthetic, structural, and functional characteristics of new optoelectronic COF materials. Next to synthesis and morphology control, electrical and optical characterization was performed, giving insights on the stacking behavior and electronic landscape within the framework. The COF was used as a new tool for directed structural control and stacking of molecular chromophore units. Furthermore, exceptionally high intrinsic charge carrier mobilities were found even on the macroscopic scale of devices, possibly enabling new applications in sensing and optoelectronic devices. Additionally, postsynthetic processes were developed to extend the portfolio of applications for synthesized COFs through modification or to improve the performance of materials through defect reduction, which is of particular interest for optoelectronic thin film-based devices

Tailoring the features of covalent organic frameworks

Covalent organic frameworks (COFs) represent a new and emerging class of functional materials built from organic subunits. These networks are formed via reversible co-condensation reactions resulting in covalent bonds based on diverse binding motifs. Due to the great variety and large number of accessible building blocks, structural and functional diversity can be achieved easily. By combining desired subunits, crystalline and porous two- or three-dimensional frameworks can be synthesized exhibiting a defined pore size and a high surface area. Crystallinity and porosity are of central importance for many characteristics of COFs such as adsorption, diffusion, and electronic transport. The possible role of COF materials applied for sensing, catalysis, and optoelectronic applications is based on their tunable characteristics which can be tailored by implementing suitable subunits. Furthermore, postsynthetic modifications can be used to adjust properties of the framework while maintaining the main aspects. In general, COFs can be synthesized during solvothermal reaction conditions followed by diverse work-up steps which have to be adapted and optimized for each system. Therefore, finding the right parameters is key for the successful synthesis of crystalline materials and mastering them enables the formation of thin films on suitable substrates. This is particularly important for device applications in the optoelectronic area. This thesis focuses on the synthesis of novel two-dimensional COFs, introducing new characteristic features into such frameworks. The different COF materials were fully characterized by various methods to ensure high crystallinity and porosity as well as elucidating their morphology and structure. Next to neat bulk and film materials, also full electronic devices were fabricated for further analysis. In addition, postsynthetic treatments concerning structural improvement and pore wall modifications were investigated. The possible applications arising from introducing additional functionality after the synthesis were a substantial part of this work. The experimental results of this thesis can be separated into three main parts: structural control as well as implementation of dyes and electroactive subunits, electrical characterization, and postsynthetic treatment methods. In general, while Chapter 1 of this thesis is introducing the main aspects of COFs and the theoretical background, Chapter 2 contains descriptions of the methods used for materials characterization. The first part of the experimental results (Chapter 3 and 4) deals with structural control including the implementation of dyes and the comparison of imine and boronate ester binding motifs. Chapter 3 is focused on the precise construction of template-free nano- and microstructures of dye-containing porous materials. The implemented organic dye diketopyrrolopyrrole was functionalized with accessible aldehyde groups. After reaction with a tetra amine-functionalized porphyrin building block the resulting DPP-TAPP-COF showed enhanced absorption capabilities. Regarding structural control, the obtained COF exhibited spontaneous aggregation into hollow microtubular assemblies with well-defined and controllable outer and inner tube diameters. A detailed mechanistic morphology investigation revealed that the whole process is time-dependent and undergoes a traceable transformation starting with sheet-like agglomerates into stable tubular microstructures via a rolling-up mechanism. As already mentioned in the third chapter (the implementation of sterically demanding dyes as building blocks for COF systems), the integration of diketopyrrolopyrrole molecules is still hampered by limited control of the binding motif in combination with the size of the backbone. In Chapter 4, the results of using a flat, rigid, and non-conjugated boronate ester bond combined with the dye and a suitable counterpart are reported. Here, structural control was achieved and led to enhanced properties and enforced specific stacking behavior. The COF was successfully synthesized and crystallinity as well as porosity could be improved as compared to the imine-connected counter-part, with even shorter reaction times. The boronate ester coupling motif guides the formation of a planar and rigid backbone and long-range molecular stacks. Furthermore, the COF exhibits application-relevant optical properties including strong absorption over the visible spectral range, broad emission into the near infrared region (NIR), and a long singlet lifetime. All the findings can be attributed to the controlled formation of molecular stacks with J-type interactions between the subcomponents in the COF. In addition, these molecular stacks showed an influence on the electronic behavior revealing electrical conductivity values of crystalline COF pellets up to 10 6 Scm-1. Further investigations on electrical conductivity and charge carrier mobility studies on different COF systems are described in Chapter 5. Here, a series of acene-based building blocks was implemented into a scaffold, i.e. benzene and anthracene dialdehyde-functionalized subunits, which show high charge carrier mobilities comparable to organic materials in single crystals. The building blocks were designed in a way to tailor the length of the resulting aromatic backbone pointing into the pore of the framework without changing the overall unit cell dimensions, i.e. the molecules were inserted perpendicular to the binding direction. This allows for a better comparison of the structures and the resulting properties. The measurements revealed that the length of the backbone has a strong influence on the achieved electrical conductivity and mobility values. Moreover, different measurement methods for conductivity in combination with mobility are compared due to the diverse theoretical backgrounds each method is based on, yielding technique-specific values. In addition, all COF samples revealed surprisingly high Hall mobility values for pressed powder pellets as well as for thin films and devices. The measured hole-only devices exhibited up to 10 3 cm2V-1s-1 for the anthracene COF, which is one of the largest values of intrinsic mobility for COFs so far. The results point towards the importance of π-overlap and hence the length of the acene unit. Further extension of the series towards the even longer pentacene unit was initiated but will be part of future studies. The third part of the experimental results deals with the different possibilities of postsynthetic treatments. In Chapter 6, a new postsynthetic treatment for covalent organic frameworks is introduced. Here, a newly synthesized anthracene-based COF (from Chapter 5) is reported followed by a postsynthetic treatment based on light-induced defect reduction. The applied laser light apparently leads to opening and reformation of imine bonds resulting in a significant decrease of defect sites and therefore a striking increase in photoluminescence. This effect was further supported by IR investigations showing a reduced intensity of aldehyde and amine vibrations and a gain of imine vibration intensity upon laser irradiation of a stoichiometric precursor mix. Another approach regarding postsynthetic treatment is presented in Chapter 7, based on chemical modification after successful COF synthesis. A novel terphenyldiboronic acid-based COF is reported which features accessible hydroxyl groups at the inner and outer pore wall environment. These functional groups serve as anchor sites for a fluorescence label which can be installed by a postsynthetic modification approach. By forming o thiocarbamate bonds, fluorescein molecules were immobilized on the inner as well as at the outer surface of the pore system. This reaction was further extended to another COF system and to other grafting moieties. In conclusion, this thesis mainly focused on the fundamental synthetic, structural, and functional characteristics of new optoelectronic COF materials. Next to synthesis and morphology control, electrical and optical characterization was performed, giving insights on the stacking behavior and electronic landscape within the framework. The COF was used as a new tool for directed structural control and stacking of molecular chromophore units. Furthermore, exceptionally high intrinsic charge carrier mobilities were found even on the macroscopic scale of devices, possibly enabling new applications in sensing and optoelectronic devices. Additionally, postsynthetic processes were developed to extend the portfolio of applications for synthesized COFs through modification or to improve the performance of materials through defect reduction, which is of particular interest for optoelectronic thin film-based devices

Keeping Control: The Role of Senescence and Development in Plant Pathogenesis and Defense

Many plant pathogens show interactions with host development. Pathogens may modify plant development according to their nutritional demands. Conversely, plant development influences pathogen growth. Biotrophic pathogens often delay senescence to keep host cells alive, and resistance is achieved by senescence- like processes in the host. Necrotrophic pathogens promote senescence in the host, and preventing early senescence is a resistance strategy of plants. For hemibiotrophic pathogens both patterns may apply. Most signaling pathways are involved in both developmental and defense reactions. Increasing knowledge about the molecular components allows to distinguish signaling branches, cross-talk and regulatory nodes that may influence the outcome of an infection. In this review, recent reports on major molecular players and their role in senescence and in pathogen response are reviewed. Examples of pathosystems with strong developmental implications illustrate the molecular basis of selected control strategies. A study of gene expression in the interaction between the hemibiotrophic vascular pathogen Verticillium longisporum and its cruciferous hosts shows processes that are fine-tuned to counteract early senescence and to achieve resistance. The complexity of the processes involved reflects the complex genetic control of quantitative disease resistance, and understanding the relationship between disease, development and resistance will support resistance breeding. View Full-Tex

Collagen in Colorectal Cancer – a mass spectrometry analysis –

In the Netherlands colon cancer is the 3rd most frequent cancer type, with annually more than 14,000 new patients, and 5000 patients die. After surgical removal of the primary colon tumor, there is a 30-40% chance of metastasis in the liver. To detect the presence of metastasis as early as possible, the patient has to regularly visit the hospital and receives CT-scans, ultrasounds, or blood tests. This thesis had as goal to find protein fragments (peptides) in urine that are elevated in patients with a liver metastasis. If this is possible,

Guiding stars to the field of dreams: Metabolically engineered pathways and microbial platforms for a sustainable lignin-based industry

Lignin is an important structural component of terrestrial plants and is readily generated during biomass fractionation in lignocellulose processing facilities. Due to lacking alternatives the majority of technical lignins is industrially simply burned into heat and energy. However, considering its vast abundance and a chemically interesting richness in aromatics, lignin is presently regarded both as the most under-utilized and promising feedstock for value-added applications. Notably, microbes have evolved powerful enzymes and pathways that break down lignin and metabolize its various aromatic components. This natural pathway atlas meanwhile serves as a guiding star for metabolic engineers to breed designed cell factories and efficiently upgrade this global waste stream. The metabolism of aromatic compounds, in combination with success stories from systems metabolic engineering, as reviewed here, promises a sustainable product portfolio from lignin, comprising bulk and specialty chemicals, biomaterials, and fuels