Glyconanobiotics: Novel Carbohydrated Nanoparticle Polymers

Carbohydrates on the cell surface conjugates to proteins and lipids and participates in biological processes as glycoconjugates. Carbohydrate functionalized nanoparticles (glyconanoparticles) constitute a good bio-mimetic model of carbohydrate presentation at the cell surface and are currently centered on many glycobiological and biomedical applications. The most of the applications have been reported using gold glyconanoparticles. A brief review of gold glyconanoparticles and some of their applications will be discussed in Chapter I. Although metallic, semiconductor and magnetic glyconanoparticles have been reported, no polyacrylate glyconanoparticles have yet to be described. Chapter II describes the first preparation of carbohydrate functionalized polymer nanoparticles by microemulsion polymerization and their characterization using scanning electron microscopy, dynamic light scattering and 1H NMR spectroscopy. This methodology can generate a large number of furanose and pyranose nanoparticle derivatives with an average particle size of around 40 nm with the protected carbohydrate hydroxyl functionality as acetyl or dimethylacetal groups. Formation of larger glyconanoparticles of around 80 nm with 3-O-acryloyl-D-glucose and 5-O-acryloyl-1-methoxy-beta-D-ribofuranose reveals the influence of free hydroxyl groups in the monomer on the particle size during polymerization, a feature which is also apparently dependent on the amount of carbohydrate in the matrix. Preparation of glyconanoparticle antibiotics, or glyconanobiotics, by microemulsion of antibiotic-conjugated carbohydrate monomers demonstrates for the first time the use of glyconanoparticles as drug delivery vehicles in Chapter III. The conjugation of an acrylated hydrophobic carbohydrate moiety to the lipophilic antibiotic makes it even more lipophilic and suitable as a co-monomer in microemulsion polymerization with styrene/butyl acrylate. Novel carbohydrate-based acrylated acyl chlorides synthesized from glucose afford antibiotic monomers with enhanced lipophilicity in a one step procedure. These drug monomers and the corresponding glyconanobiotics prepared by conjugating antibiotics such as N-thiolated-beta-lactam, ciprofloxacin, and penicillin shows biological activity against S. aureus, MRSA and B. anthracis microbes. Glyconanoparticles prepared by microemulsion polymerization of 3-O-acryloyl-D-glucose and styrene/butyl acrylate may be potentially used as recognition units in carbohydrate ligand mediated targeted drug delivery. The binding capability of the surface-exposed carbohydrates on the nanoparticle can be detected by fluorescence spectroscopy utilizing pyranine and 4,4\u27-N,N-bis(benzyl-2-boronic acid)-bipyridinium dibromide as described in Chapter IV

Glyconanobiotics: Novel Carbohydrated Nanoparticle Polymers

Carbohydrates on the cell surface conjugates to proteins and lipids and participates in biological processes as glycoconjugates. Carbohydrate functionalized nanoparticles (glyconanoparticles) constitute a good bio-mimetic model of carbohydrate presentation at the cell surface and are currently centered on many glycobiological and biomedical applications. The most of the applications have been reported using gold glyconanoparticles. A brief review of gold glyconanoparticles and some of their applications will be discussed in Chapter I. Although metallic, semiconductor and magnetic glyconanoparticles have been reported, no polyacrylate glyconanoparticles have yet to be described. Chapter II describes the first preparation of carbohydrate functionalized polymer nanoparticles by microemulsion polymerization and their characterization using scanning electron microscopy, dynamic light scattering and 1H NMR spectroscopy. This methodology can generate a large number of furanose and pyranose nanoparticle derivatives with an average particle size of around 40 nm with the protected carbohydrate hydroxyl functionality as acetyl or dimethylacetal groups. Formation of larger glyconanoparticles of around 80 nm with 3-O-acryloyl-D-glucose and 5-O-acryloyl-1-methoxy-beta-D-ribofuranose reveals the influence of free hydroxyl groups in the monomer on the particle size during polymerization, a feature which is also apparently dependent on the amount of carbohydrate in the matrix. Preparation of glyconanoparticle antibiotics, or glyconanobiotics, by microemulsion of antibiotic-conjugated carbohydrate monomers demonstrates for the first time the use of glyconanoparticles as drug delivery vehicles in Chapter III. The conjugation of an acrylated hydrophobic carbohydrate moiety to the lipophilic antibiotic makes it even more lipophilic and suitable as a co-monomer in microemulsion polymerization with styrene/butyl acrylate. Novel carbohydrate-based acrylated acyl chlorides synthesized from glucose afford antibiotic monomers with enhanced lipophilicity in a one step procedure. These drug monomers and the corresponding glyconanobiotics prepared by conjugating antibiotics such as N-thiolated-beta-lactam, ciprofloxacin, and penicillin shows biological activity against S. aureus, MRSA and B. anthracis microbes. Glyconanoparticles prepared by microemulsion polymerization of 3-O-acryloyl-D-glucose and styrene/butyl acrylate may be potentially used as recognition units in carbohydrate ligand mediated targeted drug delivery. The binding capability of the surface-exposed carbohydrates on the nanoparticle can be detected by fluorescence spectroscopy utilizing pyranine and 4,4\u27-N,N-bis(benzyl-2-boronic acid)-bipyridinium dibromide as described in Chapter IV

Hyaluronic acid based self-assembling nanosystems for CD44 target mediated siRNA delivery to solid tumors

Anticancer therapeutics employing RNA interference mechanism holds promising potentials for sequence-specific silencing of target genes. However targeted delivery of siRNAs to tumor tissues and cells and more importantly, their intracellular release at sites of interest still remains a major challenge that needs to be addressed before this technique could become a clinically viable option. In the current study, we have engineered and screened a series of CD44 targeting hyaluronic acid (HA) based self-assembling nanosystems for targeted siRNA delivery. The HA polymer was functionalized with lipids of varying carbon chain lengths/nitrogen content, as well as polyamines for assessing siRNA encapsulation. From the screens, several HA-derivatives were identified that could stably encapsulate/complex siRNAs and form self-assembled nanosystems, as determined by gel retardation assays and dynamic light scattering. Many HA derivatives could transfect siRNAs into cancer cells overexpressing CD44 receptors. Interestingly, blocking the CD44 receptors on the cells using free excess soluble HA prior to incubation of cy3-labeled-siRNA loaded HA nano-assemblies resulted in >90% inhibition of the receptor mediated uptake, confirming target specificity. In addition, SSB/PLK1 siRNA encapsulated in HA-PEI/PEG nanosystems demonstrated dose dependent and target specific gene knockdown in both sensitive and resistant A549 lung cancer cells overexpressing CD44 receptors. More importantly, these siRNA encapsulated nanosystems demonstrated tumor selective uptake and target specific gene knock down in vivo in solid tumors as well as in metastatic tumors. The HA based nanosystems thus portend to be promising siRNA delivery vectors for systemic targeting of CD44 overexpressing cancers including tumor initiating (stem-) cells and metastatic lesions

3-Aryl-4-methyl-2-quinolones Targeting Multiresistant Staphylococcus aureus Bacteria

The NorA efflux pump lowers intracellular fluoroquinolone concentrations by expelling antibiotics through the membrane of Staphylococcus aureus. We identified 3-aryl-4-methyl-2-quinolin-2-ones as compounds able to restore the activity of the NorA substrate, ciprofloxacin, against resistant S. aureus strains, and acting as efflux pump inhibitors (EPI). In particular, 5-hydroxy-7-methoxy-4-methyl-3-phenylquinolin-2-one (6 c) presents both an EPI and an antimicrobial effect. Its efficacy and safety make it a potential candidate for further investigations