Synthesis and Applications of Dynamic Multivalent Nanostructures

This thesis focuses on the design, synthesis and development of dynamic multivalent nanostructures such as supramolecular dendrimers, liposomes and gold-functionalized nanostructures. These structures can be used for drug delivery and molecular sensing applications. This thesis is divided into three parts: In part one, a general introduction to self-assembly, dynamic systems, metalligand exchange, nanostructured dendritic scaffolds, liposomes and gold nanostructures is given. In part two, a microwave approach is presented as an efficient method for the regioselective deuteration of bipyridine scaffolds. Dynamic systems based on transition metal-bipyridine coordination complexes were investigated. The compositional self-adaptation and kinetics of these dynamic systems were successfully assessed by ESI-MS. Based on this amphiphilic dendrimers/metallodendrimers were also designed and synthesized via  a convergent strategy. Their ability to self-assemble into supramolecular assemblies and their controlled disassembly was effectively demonstrated. In part three, two types of drug delivery systems based on dynamic multivalent nanostructures of glycodendrimers/metalloglycodendrimers and drugpresenting liposomes were developed. The dynamic self-assembly of these architectures into supramolecular nanostructures with site-specific functionality through interacting carbohydrate or cholesterol moieties was assessed. The host-guest interaction/encapsulation and controlled release with external stimuli were studied using a fluorescent probe, as well as selected drug molecules. The antibacterial property of the drug delivery systems was also evaluated, demonstrating an enhanced bactericidal activity. A new, rapid and simple approach for the functionalization of plasmonic gold nanostructured surfaces was also developed. The optical performance and light-specific sensitivity of the fluorescent probe on the resulting nanostructures were also presented.QC 20151119</p

Rapid, regioselective deuteration of dimethyl-2,2'-bipyridines via microwave-assistance

Isotopically pure [D6]-dimethyl-2,2′-bipyridine derivatives were selectively and rapidly formed using microwave-assisted regioselective deuteration of the methyl moieties of the parent bipyridine in a deuterium oxide solution. For instance, [D6]-4,4′-dimethyl-2,2′-bipyridine was formed in quantitative yield within 15 minutes, in a simple and convenient process.QC 20151119</p

Glyconanomaterials for biosensing applications

Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.QC 20150715</p

Светодиодное освещение: проблемы трансформации синего излучения в белый свет

Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.QC 20150715</p

Laser-induced, Surface Plasmon-enhanced Two-photon Excitation for Efficient Chemical Functionalization of Nanostructured Gold Surfaces

Functionalized gold nanostructures with efficient, broadband absorption properties are of interest for a variety of biomedical applications. In this study, we report a plasmon-enhanced functionalization methodology that results in selective surface conjugation of a fluorescent probe via two-photon excitation under visible-wavelength laser irradiation. The fluorescent probe was designed to incorporate a thiolated 4-piperidinyl-1,8-naphthalimide (SNaph) entity, carrying a photolabile 6-nitroveratryl (NV) protecting group, straightforwardly synthesized in a few steps in good yield. Efficient plasmon-enhanced photodeprotection of the NV-group, followed by thiol-gold bond formation on gold nanoisland substrates was recorded upon exposure to 650 nm laser light, supported by confocal laser scanning microscopy (CLSM). Photolysis of the labile NV-group, thereby efficiently exposing the free mercapto group of the thiolated 1,8-naphthalimide, was recorded upon UV-irradiation at 350 nm, whereas no cleavage occurred at 650 nm. No conjugation occurred on featureless, gold-plated flat substrates under the same conditions. Surface plasmon-enhanced two-photon excitation at plasmonic hotspots in the absorber layer thus resulted in selective and efficient conjugation of the fluorescent probe to the structured surfaces. The resulting laser-assisted approach introduces the advantage of accomplishing selective molecular functionalization at plasmonic hotspots, owing to the combined, simultaneous effects of long-wavelength deprotection and spontaneous conjugation