ABSTRACT
We report the synthesis and properties of temperature- and pH-responsive p([NIPAm-co-PEGMA] (core)/[NIPAm-co-AAc] (shell)) nanogels with narrow size distributions, tunable sizes and increased drug loading efficiencies. The core-shell nanogels were synthesized using an optimized two-stage seeded polymerization methodology. The core-shell nanogels show a narrow size distribution and controllable physico-chemical properties. The hydrodynamic sizes, charge distributions, temperature-induced volume phase transition behaviors, pH-responsive behaviors and drug loading capabilities of the core-shell nanogels were investigated using transmission electron microscopy, zeta potential measurements, dynamic light scattering and UV-Vis spectroscopy. The size of the core-shell nanogels was controlled by polymerizing NIPAm with crosslinker poly(ethylene glycol) dimethacrylate (PEGDMA) of different molecular weights (Mn-200, 400, 550 and 750 g/mol) during the core synthesis. It was found that the swelling/deswelling kinetics of the nanogels was sharp and reversible; with its volume phase transition temperature in the range of 40â»42 °C. Furthermore, the nanogels loaded with l-3,4-dihydroxyphenylalanine (L-DOPA), using a modified breathing-in mechanism, showed high loading and encapsulation efficiencies, providing potential possibilities of such nanogels for biomedical applications.
ABSTRACT
A new optically active uridine nucleoside analogue in which a substituted 1,4-dioxane ring functioned as the sugar analogue was prepared from L-tartaric acid. The nucleoside analogue was further converted into the corresponding protected dinucleotide.
Subject(s)
Dioxanes/chemistry , Nucleosides/chemical synthesis , Uridine/chemistry , Molecular Conformation , Molecular Structure , Nucleic Acid Conformation , Nucleosides/chemistry , StereoisomerismABSTRACT
Enantioselective syntheses from dimethyl tartrate of 1,3,5-triazine homo-N-nucleoside analogs, containing a 1,4-dioxane moiety replacing the sugar unit in natural nucleosides, were accomplished. The triazine heterocycle in the nucleoside analogs was further substituted with combinations of NH(2), OH and Cl in the 2,4-triazine positions.
Subject(s)
Carbohydrates/chemical synthesis , Dioxanes/chemical synthesis , Nucleosides/chemical synthesis , Triazines/chemical synthesis , Carbohydrates/chemistry , Dioxanes/chemistry , Nucleosides/chemistry , Triazines/chemistry , Uracil/chemistryABSTRACT
A dioxane homo-sugar analog, (2S,5S)-and (2R,5S)-5-[(4S)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-iodomethyl-1,4-dioxane was prepared from (2R,3R)-dimethyl tartrate, and further elaborated into the corresponding homo-N-nucleoside analogs by its reactions with uracil and adenine, respectively.
Subject(s)
Dioxanes/chemistry , Nucleosides/chemical synthesis , Nuclear Magnetic Resonance, Biomolecular , Nucleosides/chemistry , StereoisomerismABSTRACT
Water soluble homo-base polynucleotide analogues were synthesized in which polyvinyl alcohol and partially phosphonated polyvinyl alcohol constituted the backbones,onto which were grafted uracil or adenine via 1,3-dioxane spacers formed by acetal formation with the 1,3-diol moieties in PVA. The resulting adenine-PVA polynucleotide analogs exhibited hyperchromic effects, which was not the case for the corresponding uracil compounds. Mixtures of the adenine- and aracil PVA-phosphate polynucleotide analogs in solutions exhibited characteristic S-shaped UV-absorbance vs temperature and melting curves with melting points at approximately 40 degrees C.
Subject(s)
Polynucleotides/chemical synthesis , Polyvinyl Alcohol/chemistry , Adenine/chemistry , Phosphates/chemistry , Polynucleotides/chemistry , Solubility , Spectrophotometry, Ultraviolet , Temperature , Uracil/chemistryABSTRACT
The selective synthesis of sulfonate surfactants with side chains containing ether- and hydroxy groups was carried out using cyclic sulfates as epoxide analogues. The main chain was elaborated from 1,2-dodecane sulfate by the addition of various hydroxy/alkoxysulfonates. Ethyleneoxy- and 1,2-propyleneoxy- groups were introduced using ethylene sulfate and 1,2-propylene sulfate, respectively.
Subject(s)
Sulfonic Acids/chemical synthesis , Surface-Active Agents/chemical synthesis , Hydroxylation , Magnetic Resonance Spectroscopy , Stereoisomerism , Sulfonic Acids/chemistry , Surface-Active Agents/chemistryABSTRACT
A method was developed for the analysis of a number of surfactants which contained no UV-chromophores, using RP-HPLC with Indirect Photometric Detection, IPD. Pyridinium salts such as N-methylpyridinium iodide, N-methyl-2,2'-dipyridinium iodide and N,N'-dimethyl-2,2'-dipyridinium diiodide, were used as the visualization reagents, forming ion-pair complexes with the sulfonate surfactants. This allowed ordinary UV-detection. N-methylpyridinium iodide proved to be a suitable reagent, both with respect to ease of preparation and response. The eluents consisted of mixtures of acetonitrile and water, being 0.1 - 0.25 mM with respect to pyridinium salt. The method was sensitive and exhibited good signal to noise ratios, as well as linear responses over a wide concentration range. All of the analyzed surfactants were separated, including the diastereomeric forms of some of the surfactants.