Influence of Surface States on the Optical and Cellular Property of Thermally Stable Red Emissive Graphitic Carbon Dots.

Red emissive carbon dots from sucrose (SCD) were synthesized using a facile, isolation-free, one-pot method via microwave pyrolysis. Various passivation agents were used along with sucrose, and a relative change in the chemical and optical properties of the carbon dots was investigated. A detailed systematic study of the effect of various passivations, different solvents, pHs, and temperatures on optical properties was carried out. The influence of excitation wavelength and passivation on photoluminescence (PL) is discussed considering the functional groups associated with the passivating agents. The effect of different solvents on dispersibility and PL behavior has been understood in terms of the dielectric properties of the solvents. The decrease in PL intensity of SCD from pH 3 to 11 facilitates pH sensing. The PL of SCD was found to be essentially stable between the temperature range of 20 and 80 °C. Additionally, the effects of physicochemical properties with respect to passivation, such as charge and surface chemistry in determining the cellular uptake and cytotoxicity, are also addressed. Aside from sensors, the potential of SCDs as bioimaging agents has also been studied for mammalian cells. Moreover, SCD exhibits excellent PL stability investigated under different storage conditions for 15 days.

Synthesis of Sucrose Fatty Acid Esters by Using Mixed Carboxylic-fatty Anhydrides.

Fatty acid sugar esters are non-ionic surfactant active agents with excellent performance and many uses. This work is devoted to the synthesis of sugar esters by the esterification reaction of sugar with mixed carboxylicpalmitic anhydrides using resin Amberlyst-15 as heterogeneous acid catalyst. These anhydrides should be stable and react as acylating agents. Influence of different reaction parameters, such as the molar ratio (sucrose/anhydride), the type of solvent and the reaction time on the yield of the esterification reaction were studied. The esterification reaction of sucrose with mixed palmitic benzoic anhydride leads to a mixture of sucrose esters of palmitic acid with a good percentage of conversion. The mixed anhydride was both reactive and selective for the preparation of fatty acid ester.

A new synthetic methodology for pyridinic sucrose esters and their antibacterial effects against Gram-positive and Gram-negative strains.

Described are the development of a new synthetic method using ultrasonic irradiation and sodium methoxide as catalyst for a series of pyridinic sucrose esters (py-SEs), derived from transesterification of sucrose with picolinic, nicotinic and isonicotinic methyl esters. The reaction was optimized using a 32 x 2 experimental design, the reaction time, temperature and sucrose: methyl ester molar ratio being evaluated. The method proved to be efficient for obtaining monosubstituted esters (≥83%) with high methyl ester consumption (≥79%). The monosubstituted py-SEs were isolated by semipreparative HPLC, characterized by high-resolution mass spectrometry, calorimetry, vibrational spectroscopy, and 1H and 13C NMR. The py-SEs were tested against E. coli, S. aureos, and P. aeruginosa bacteria with minimum inhibitory concentration values equal or inferior to the reference drugs for both E. coli and P. aeruginosa.

LyoPRONTO: an Open-Source Lyophilization Process Optimization Tool.

This work presents a new user-friendly lyophilization simulation and process optimization tool, freely available under the name LyoPRONTO. This tool comprises freezing and primary drying calculators, a design-space generator, and a primary drying optimizer. The freezing calculator performs 0D lumped capacitance modeling to predict the product temperature variation with time which shows reasonably good agreement with experimental measurements. The primary drying calculator performs 1D heat and mass transfer analysis in a vial and predicts the drying time with an average deviation of 3% from experiments. The calculator is also extended to generate a design space over a range of chamber pressures and shelf temperatures to predict the most optimal setpoints for operation. This optimal setpoint varies with time due to the continuously varying product resistance and is taken into account by the optimizer which provides varying chamber pressure and shelf temperature profiles as a function of time to minimize the primary drying time and thereby, the operational cost. The optimization results in 62% faster primary drying for 5% mannitol and 50% faster primary drying for 5% sucrose solutions when compared with typical cycle conditions. This optimization paves the way for the design of the next generation of lyophilizers which when coupled with accurate sensor networks and control systems can result in self-driving freeze dryers.

Electrosprayed naringin-loaded microsphere/SAIB hybrid depots enhance bone formation in a mouse calvarial defect model.

The burst release of active osteogenic factors, which is not beneficial to osteogenesis, is commonly encountered in bone tissue engineering. The aims of this study were to prepare naringin-loaded microsphere/sucrose acetate isobutyrate (Ng-m-SAIB) hybrid depots, reduce the burst release of naringin (Ng), and improve osteogenesis. The morphology and size distributions of electrosprayed Ng-microspheres were characterized by scanning electron microscopy (SEM). The Ng-microspheres and Ng-m-SAIB depots were characterized by Fourier transform infrared spectroscopy (FTIR) and in vitro release studies. In vitro osteoblast-microsphere interactions and in vivo osteogenesis were assessed after implantation of Ng-m-SAIB depots. The addition of sucrose acetate isobutyrate (SAIB) to monodisperse Ng-microspheres did not cause a change in the chemical structure. The performances of the microspheres in osteoblast-microsphere interactions were better when the naringin content was 4% than when it was at 2% and 6%. On the first day following the loading of Ng-microspheres (2%, 4%, and 6%) into SAIB depots, the burst release was reduced dramatically from 70.9% to 6.3%, 73.1% to 7.2%, and 73.9% to 9.9%, respectively. In addition, after 8 weeks, the new bone formation rate in the calvarial defects of SD rats receiving Ng-m-SAIB was 53.1% compared to 21.2% for the control group and 16.1% for the microsphere-SAIB group. These results demonstrated that Ng-m-SAIB hybrid depots may have promise in bone regeneration applications.

Synthesis of d-fructose conjugated ligands via C6 and C1 and their corresponding [Ru(bpy)2(L)]Cl2 complexes.

A pyridyl triazole (pyta) modified sucrose ligand was prepared in a seven step synthesis using d-glucose as the protection group for d-fructose and starting from commercially available sucrose. After complexation with Ru(bpy)2Cl2 precursor, the sucrose-conjugated Ru complex of the general formula [Ru(bpy)2(L)]Cl2 was formed. Acidic cleavage of the d-glucose unit led to the first d-fructose conjugated metal complex viad-fructose C6 in literature. Additionally, pyta-modified d-fructose via C1 and the corresponding Ru complex were synthesized. All compounds were analyzed by Rf values, specific rotation, NMR, IR, UV/Vis and fluorescence spectroscopy, mass spectrometry and elemental analysis.

Synthesis of a suite of click-compatible sugar analogs for probing carbohydrate metabolism.

Metabolic labeling based on the click chemistry between alkynyl and azido groups offers a powerful tool to study the function of carbohydrates in living systems, including plants. Herein, we describe the chemical synthesis of six alkynyl-modified sugars designed as analogs to D-glucose, D-mannose, L-rhamnose and sucrose present in plant cell walls. Among these new alkynyl probes, four of them are the 6-deoxy-alkynyl analogs of the corresponding sugars and do not possess any 6-OH groups. The other two are based on a new structural design, in which an ethynyl group is incorporated at the C-6 position of the sugar and the 6-OH group remains. The synthetic routes for both types of probes share common aldehyde intermediates, which are derived from the corresponding 6-OH precursor with other hydroxy groups protected. The overall synthesis sequence of these probes is efficient, concise, and scalable.

Synthesis, Characterization, Antimicrobial and Antitumor Activities of Sucrose Octa(N-ethyl)carbamate.

Sucrose octa(N-ethyl)carbamate was synthesized directly from sucrose and ethyl isocyanate, and its structure was confirmed by various analytical methods, such as (1)H and (13)C NMR, FTIR, m.p., MS, and optical rotation. Its antibacterial, antifungal and cytotoxic activities were investigated. It exhibited strong inhibition against all bacteria tested, namely S. aureus (MIC 0.18±0.006), B. cereus (MIC 0.094±0.000), M. flavus (MIC 0.28±0.01), L. monocytogenes (MIC 0.18±0.006), P. aeruginosa (MIC 0.094±0.002), S. typhimurium (MIC 0.094±0.002), E. coli (MIC 0.18±0.006) and E. cloacae (MIC 0.18±0.006) and strong antifungal activity towards T. viride (MIC 0.09 ± 0.006), A. versicolor (MIC 0.18 ± 0.01), A. ochraceus (MIC 0.375 ± 0.01) and P. ochrochloron (MIC 0.375 ± 0.04). Furthermore, it showed moderate antitumor potential against human breast (GI50 357.20±14.12), colon (GI50 332.43±11.19) and cervical (GI50 282.67±3.97) cell lines and, more important, without hepatotoxicity.

Antimicrobial and cytotoxic activities of 1,2,3-triazole-sucrose derivatives.

A library of 1-(1',2,3,3',4,4',6-hepta-O-acetyl-6'-deoxy-sucros-6'-yl)-1,2,3-triazoles have been investigated for their antibacterial, antifungal and cytotoxic activities. Most of the target compounds showed good inhibitory activity against a variety of clinically and food contaminant important microbial pathogens. In particular, 1-(1',2,3,3',4,4',6-hepta-O-acetyl-6'-deoxy-sucros-6'-yl)-4-(4-pentylphenyl)-1,2,3-triazole (5) was highly active against all the tested bacteria with minimal inhibitory concentrations (MICs) ranging between 1.1 and 4.4 µM and bactericidal concentrations (MBCs) from 2.2 and 8.4 µM. The compound 1-(1',2,3,3',4,4',6-hepta-O-acetyl-6'-deoxy-sucros-6'-yl)-4-(4-bromophenyl)-1,2,3-triazole (3) showed antifungal activity with MICs from 0.6 to 4.8 µM and minimal fungicidal concentrations (MFCs) ranging between 1.2 and 8.9 µM. Furthermore, some of the compounds possessed moderate cytotoxicity against human breast, lung, cervical and hepatocellular carcinoma cell lines, without showing toxicity for non-tumor liver cells. The above mentioned derivatives represent promising leads for the development of new generation of sugar-triazole antifungal agents.

Radiosynthesis of 6'-Deoxy-6'[18F]Fluorosucrose via Automated Synthesis and Its Utility to Study In Vivo Sucrose Transport in Maize (Zea mays) Leaves.

Sugars produced from photosynthesis in leaves are transported through the phloem tissues within veins and delivered to non-photosynthetic organs, such as roots, stems, flowers, and seeds, to support their growth and/or storage of carbohydrates. However, because the phloem is located internally within the veins, it is difficult to access and to study the dynamics of sugar transport. Radioactive tracers have been extensively used to study vascular transport in plants and have provided great insights into transport dynamics. To better study sucrose partitioning in vivo, a novel radioactive analog of sucrose was synthesized through a completely chemical synthesis route by substituting fluorine-18 (half-life 110 min) at the 6' position to generate 6'-deoxy-6'[(18)F]fluorosucrose ((18)FS). This radiotracer was then used to compare sucrose transport between wild-type maize plants and mutant plants lacking the Sucrose transporter1 (Sut1) gene, which has been shown to function in sucrose phloem loading. Our results demonstrate that (18)FS is transported in vivo, with the wild-type plants showing a greater rate of transport down the leaf blade than the sut1 mutant plants. A similar transport pattern was also observed for universally labeled [U-(14)C]sucrose ([U-(14)C]suc). Our findings support the proposed sucrose phloem loading function of the Sut1 gene in maize, and additionally demonstrate that the (18)FS analog is a valuable, new tool that offers imaging advantages over [U-(14)C]suc for studying phloem transport in plants.

Amide-linked N-methacryloyl sucrose containing polymers.

1',2,3,3',4,4',6-Hepta-O-benzyl-6'-N-methacryloyl-6'-deoxysucrose 1, 6'-deoxy-6'-N-methacryloyloxyethylureido sucrose 2 and 6,6'-dideoxy-6,6'-N-dimethacryloyloxyethylureido sucrose 3 have been homo-polymerized and copolymerized with styrene by a free radical process, yielding polymer materials with pendant sucrose moieties, attached to the polymer backbone via amide linkages. The results demonstrated that varying the structural features of the monomers, greatly affected the thermal and rheological properties of the polymers. The polymer materials obtained have been characterized by NMR, MALDI-TOF, DSC, AFM and EWC (equilibrium water content). The efficient synthesis of the three novel, regioisomerically pure, N-methacryloylamide sucrose-containing monomers (1, 2 and 3) have been described.

Efficient microwave assisted synthesis of novel 1,2,3-triazole-sucrose derivatives by cycloaddition reaction of sucrose azides and terminal alkynes.

Novel 1-(1',2,3,3',4,4',6-hepta-O-acetyl-6'-deoxy-sucros-6'-yl)-4-substituted-1,2,3-triazoles were synthesized by microwave assisted copper catalyzed 1,3-dipolar cycloaddition of sucrose derived azides with terminal alkynes in excellent yields and in short reaction times. The compound 1',2,3,3',4,4',6-hepta-O-acetyl-6'-azido-6'-deoxy-sucrose was regioselectively synthesized from sucrose by improved procedure and used for the cycloadditions. By combining carbohydrate and 1,2,3-triazole structural motifs, a library of 1,2,3-triazole-sucrose conjugates have been obtained.

Chemical synthesis of 1'-deoxy-1'-fluorosucrose.

The first chemical synthesis of 1'-deoxy-1'-fluorosucrose has been accomplished in eight steps from sucrose by an unlikely, but ultimately successful, SN2 displacement reaction.

Amphiphilic copolymers of sucrose methacrylate and acrylic monomers: bio-based materials from renewable resource.

Regioselective sucrose 1'-O-methacrylate obtained by transesterification catalyzed by Proteinase-N was copolymerized with hydrophilic N-isopropylacrylamide and hydrophobic methyl methacrylate in different molar ratios by free radical polymerization. The copolymers were characterized by (13)C nuclear magnetic resonance spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetry. Solubility and phase behavior of aqueous solutions were also investigated. The glass transition of the copolymers presents a positive deviation from the values of the homopolymers due to the high density of inter and intramolecular hydrogen bonding. Their solubility is strongly dependent on the composition. Copolymers poor in methyl methacrylate are water soluble, while copolymers richer in methyl methacrylate behaves as hydrogel. These hydrogels are not chemically crosslinked and their form can be design prior swelling by the conventional processing methods, such as solvent casting and extrusion for instance. Copolymers of N-isopropylacrylamide are water soluble and their aqueous solutions present a lower critical solution temperature behavior forming thermoreversible hydrogels.

CuAAC-mediated diversification of aminoglycoside-arginine conjugate mimics by non-reducing di- and trisaccharides.

Di- and triguanidinylation of trehalose, sucrose, and melizitose has been achieved via a Huisgen-cycloaddition approach. They can serve as aminoglycoside-arginine conjugate mimics, which has been demonstrated by their biological profiles in assays against Bacillus subtilis. For comparative studies, tetraguanidinylated neamine and kanamycin derivatives have also been synthesized and evaluated.

Synthesis of 6'-deoxy-6'-fluorosucrose.

A facile synthesis of 6'-deoxy-6'-fluorosucrose has been developed. The title compound is available in six linear steps in 44% overall yield from commercially available sucrose. The synthesis involves rapid and convenient fluorination and deprotection conditions. This procedure would be very useful for the incorporation of radioactive [(18)F].

Synthesis and antiproliferative activity of helonioside A, 3',4',6'-tri-O-feruloylsucrose, lapathoside C and their analogs.

The first total synthesis of natural phenylpropanoid sucrose esters (PSEs) helonioside A 1, 3',4',6'-tri-O-feruloylsucrose 2 and lapathoside C 3 along with 17 unnatural PSE analogs has been successfully accomplished in a short and simple synthetic route. A selected set of 17 synthesized PSEs were evaluated for the antiproliferative activity against human cervical epithelioid carcinoma (HeLa) cell lines using MTS assay method. Eleven (11) compounds showed significant antiproliferative activity with their IC(50)values ranging from 0.16 to 6.01 µM. The structure-activity-relationship studies revealed that the antiproliferative activity is influenced by the lipophilicity and number of feruloyl substituents on these compounds. The preliminary screening indicated that these compounds are potentially very valuable source for new lead chemotherapeutics.

Efficient synthesis and characterization of lactulosucrose by Leuconostoc mesenteroides B-512F dextransucrase.

This work describes an efficient enzymatic synthesis and NMR structural characterization of the trisaccharide ß-D-galactopyranosyl-(1→4)-ß-D-fructofuranosyl-(2→1)-α-D-glucopyranoside, also termed as lactulosucrose. This oligosaccharide was formed by the Leuconostoc mesenteroides B-512F dextransucrase-catalyzed transfer of the glucosyl residue from sucrose to the 2-hydroxyl group of the reducing unit of lactulose. The enzymatic reaction was carried out under optimal conditions, i.e., at 30 °C in 20 mM sodium acetate buffer with 0.34 mM CaCl(2) at pH 5.2, and the effect of factors such as reaction time (0-48 h), enzyme charge (0.8, 1.6, and 2.4 U mL(-1)), and sucrose:lactulose concentration ratios (20:40, 30:30, and 40:20, expressed in g/100 mL) on the formation of transfer products were studied. The highest formation in lactulosucrose was attained at 8 and 24-32 h by using 20%:40% and 30%:30% sucrose:lactulose mixtures, respectively, with 1.6 or 2.4 U mL(-1) dextransucrase, leading to lactulosucrose yields of 27-35% in weight respect to the initial amount of lactulose. Furthermore, minor tetra- and pentasaccharide, both probably derived from lactulose, were also detected and quantified. Likewise, the capacity of lactulosucrose to act as D-glucosyl donor once the sucrose was consumed, could explain its decrease from 16 to 24 h when the highest charge of dextransucrase was used. Considering the chemical structure of the synthesized oligosaccharides, lactulosucrose and its derivatives could potentially be excellent candidates for an emerging prebiotic ingredient.

Short synthesis of diamide-linked sucrose macrocycles.

A convenient route to macrocyclic diamide-linked macrocyclic derivatives with a sucrose scaffold is presented. Reaction of sucrose based amines (o- and m-) with acid dichlorides afforded the monomeric macrocycles in excellent yields, while reaction of the p-amines also provided dimeric products.

Sucrose analogs: an attractive (bio)source for glycodiversification.

Sucrose is a widespread carbohydrate in nature and is involved in many biological processes. Its natural abundance makes it a very appealing renewable raw material for the synthetic production of high-valued molecules. To further diversify the structure and the inherent properties of these molecules, the access to sucrose analogs is of utmost interest and has historically been widely explored through chemical means. Nature also offers a large panel of sucrose-scaffold derivatives, including phosphorylated or highly substituted phenylpropanoid esters amenable to transformation. Additionally, the use of microorganisms or enzymes could provide an alternative ecologically-compatible manner to diversify sucrose-scaffold derivatives to enable the synthesis of oligo- or polysaccharides, glycoconjugates or polymers that could exhibit original properties for biotechnological applications. This review covers the main biological routes to sucrose derivatives or analogs that are prevalent in nature, that can be obtained via enzymatic processes and the potential applications of such sucrose derivatives in sugar bioconversion, in particular through the engineering of substrates, enzymes or microorganisms.