Development of benzaldehyde-pyrazoline hybrids for functionalization of polymers with fluorescent pendant moieties.

Compounds with a pyrazoline scaffold are useful as sensors for fluorescence detection of different types of analytes. Recovery of a pyrazoline-based sensor with a view to use it recurrently would be more facile when the sensing molecule is attached to a solid support. A reaction sequence has been designed to synthesize two benzaldehyde-pyrazoline hybrids as examples of a hitherto unknown type of compounds to be employed for the potential derivatization of polymers containing primary amino groups through azomethine formation. All intermediates, including the fairly unstable N1 -unsubstituted pyrazolines, along with the target compounds have been structurally characterized, with an emphasis on their particular NMR features. Examination of the photophysical properties of these benzaldehyde-pyrazoline hybrids showed that, despite the shortening of the extended N1-N2-C3 conjugated system common to 1,3,5-triarylpyrazolines through the replacement of the aryl at N1 by an aryloxyacetyl moiety, the novel compounds exhibit emission maxima at approximately 350 nm. Moreover, the introduction of a moderately electron-withdrawing substituent such as chlorine in the phenyl at C3 of pyrazoline leads to an amplification of fluorescence intensity.

Silver Nanoparticles Synthesized from Abies alba and Pinus sylvestris Bark Extracts: Characterization, Antioxidant, Cytotoxic, and Antibacterial Effects.

In recent years, phytofunctionalized AgNPs have attracted great interest due to their remarkable biological activities. In the present study, AgNPs were synthesized using Abies alba and Pinus sylvestris bark extracts. The chemical profile of these bark extracts was analyzed by LC-HRMS/MS. As a first step, the synthesis parameters (pH, AgNO3 concentration, ratio of bark extract and AgNO3, temperature, and reaction time) were optimized. The synthesized AgNPs were characterized by ATR-FTIR spectroscopy, DLS, SEM, EDX, and TEM. Their antioxidant, cytotoxic, and antibacterial properties were evaluated by the DPPH, ABTS, MTT, and broth microdilution assays, respectively. Abies alba and Pinus sylvestris bark extract-derived AgNPs were well-dispersed, spherical, small (average particle size of 9.92 and 24.49 nm, respectively), stable (zeta potential values of -10.9 and -10.8 mV, respectively), and cytotoxic to A-375 human malignant melanoma cells (IC50 = 2.40 ± 0.21 and 6.02 ± 0.61 µg/mL, respectively). The phytosynthesized AgNPs also showed antioxidant and antibacterial effects.

Formulation of Phytosomes with Extracts of Ginger Rhizomes and Rosehips with Improved Bioavailability, Antioxidant and Anti-Inflammatory Effects In Vivo.

The poor water solubility of natural antioxidants restricts their bioavailability and therapeutic use. We aimed to develop a new phytosome formulation with active compounds from extracts of ginger (GINex) and rosehips (ROSAex) designed to increase their bioavailability, antioxidant and anti-inflammatory properties. The phytosomes (PHYTOGINROSA-PGR) were prepared from freeze-dried GINex, ROSAex and phosphatidylcholine (PC) in different mass ratios using the thin-layer hydration method. PGR was characterized for structure, size, zeta potential, and encapsulation efficiency. Results showed that PGR comprises several different populations of particles, their size increasing with ROSAex concentration, having a zeta potential of ~-21mV. The encapsulation efficiency of 6-gingerol and ß-carotene was >80%. 31P NMR spectra showed that the shielding effect of the phosphorus atom in PC is proportional to the amount of ROSAex in PGR. PGR with a mass ratio GINex:ROSAex:PC-0.5:0.5:1 had the most effective antioxidant and anti-inflammatory effects in cultured human enterocytes. PGR-0.5:0.5:1 bioavailability and biodistribution were assessed in C57Bl/6J mice, and their antioxidant and anti-inflammatory effects were evaluated after administration by gavage to C57Bl/6J mice prior to LPS-induced systemic inflammation. Compared to extracts, PGR induced a 2.6-fold increase in 6-gingerol levels in plasma and over 40% in the liver and kidneys, in parallel with a 65% decrease in the stomach. PGR treatment of mice with systemic inflammation increased the sera antioxidant enzymes paraoxonase-1 and superoxide dismutase-2 and decreased the proinflammatory TNFα and IL-1ß levels in the liver and small intestine. No toxicity was induced by PGR either in vitro or in vivo. In conclusion, the phytosome formulation of GINex and ROSAex we developed resulted in stable complexes for oral administration with increased bioavailability, antioxidant and anti-inflammatory potential of their active compounds.

Quantum dots assembled from an aziridinium based hybrid perovskite displaying tunable luminescence.

3D hybrid perovskites based upon small organic cations gave start to a new intensively growing class of semiconducting materials. Here we report on the elaboration of quantum dots of a recently emerged new perovskite (AzrH)PbBr3 (AzrH = aziridinium cation). By employing the antisolvent precipitation technique and stabilization with a cationic surfactant we succeeded in obtaining quantum dots that display tunable luminescence. This piece of work shows the perspective of aziridinium-based materials for the elaboration of advanced photonic nanostructures.

Electrospinning of Cyclodextrin-Oligolactide Derivatives.

The materials used for the preparation of electrospun mats exhibit a large variety. Among them, cyclodextrins (CDs) and their derivatives have received thorough attention. Herein, we focus on the preparation of electrospun fibers based on biodegradable cyclodextrin-oligolactide (CDLA) derivatives, which may be qualified as polymer-free cyclodextrin. CDLA was prepared by ring opening of L-lactide initiated by the ß-cyclodextrin. A clear structural image of the high-purity CDLA product was proved by MALDI MS. Preparation of the electrospun mats was optimized by taking into consideration the electrospinning parameters such as applied voltage, needle-to-collector distance, flow rate, the concentration of cyclodextrin solutions, and solvent type. The obtained electrospun fibers were morphologically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS). SEM allowed the optimization of the electrospinning process to obtain beadless fibers with submicronic diameters. Further analysis by TEM and SAXS revealed the inner structural features of the CDLA-based filaments. Our results showed that the high purity CDLA materials, structurally well-defined at the molecular level, are suitable for the preparation of electrospun mats by using dimethylformamide or a water/acetonitrile mixture as electrospinning solvents, similar to lower molecular weight commercial cyclodextrin derivatives.

Cobalt Ferrite Particles Produced by Sol-Gel Autocombustion and Embedded in Polysilane: An Innovative Route to Magnetically-Induced Fluorescence Composites.

Fluorescence detection is currently one of the commonly used techniques worldwide. Through this work, the preparation and optical properties of an interesting composite material are discussed. It is shown that encapsulating cobalt spinel ferrite (CoFe2O4), obtained by the sol-gel autocombustion method, into poly[diphenyl-co-methyl(H)]silane matrix leads to fluoromagnetic particles (PSCo) with intriguing optical properties. Transmission electron microscopy, combined with energy-dispersive X-ray analysis, showed 500 nm large spherical structures containing a core (around 400 nm in diameter) composed of magnetic ferrite particles, surrounded by a thin layer of semiconductive fluorescent polymer. The as-obtained material exhibited ferrimagnetic properties. The FTIR spectrum confirmed that the Si-H functionality of the polysilane was preserved. UV spectroscopy combined with molecular modeling studies indicated that the magnetic core had a strong influence on the intramolecular electron transitions characteristic of the σ-conjugated polysilane. Further analysis by steady-state fluorescence spectroscopy revealed that the internal magnetic field strongly enhances the polysilane emission. This property will be further investigated in the future in order to develop new detection devices.

Emulsion Gels as Precursors for Porous Silicones and All-Polymer Composites-A Proof of Concept Based on Siloxane Stabilizers.

In spite of its versatility, the emulsion templating method is rather uncommon for the preparation of porous silicones. In this contribution, two siloxane-containing stabilizers, designed to be soluble in polar (water) and non-polar (toluene) solvents, respectively, were used in low concentrations to produce stable emulsions, wherein polysiloxane gels were obtained by UV-photoinitiated thiol-ene click cross-linking. The stabilizers exhibited negative interfacial tension, as measured by Wilhelmy plate tensiometry. The emulsion gels evolved into porous silicones (xerogels), with tunable morphology and properties. According to TEM and SEM investigations, the emulsion template was preserved in the final materials. Several parameters (e.g., the structure of the polysiloxane precursors, composition of the emulsion gels, nature of the continuous phase, cross-linking conditions, or additives) can be varied in order to obtain porous elastic materials with desired properties, such as Janus membranes, absorbent monoliths, all-polymer porous composites, or silicone-swollen gels. The feasibility of these types of materials was tested, and exemplary porous silicones were briefly characterized by contact angle measurements, mechanical testing, and absorption tests. The proposed method is simple, fast, and economic, uses very little amounts of stabilizers, and can be adjusted as a green technique. In this contribution, all the silicon-based materials with a convenient design were prepared in house.

Binary Silicone Elastomeric Systems with Stepwise Crosslinking as a Tool for Tuning Electromechanical Behavior.

Interpenetrating polymer networks (IPNs) represent an interesting approach for tuning the properties of silicone elastomers due to the possible synergism that may occur between the networks. A new approach is presented, which consists of mixing two silicone-based networks with different crosslinking pathways; the first network being cured by condensation route and the second network by UV curing. The networks were mixed in different ratios and the resulted samples yield good mechanical properties (improved elongations, up to 720%, and Young's modulus, 1 MPa), thermal properties (one glass transition temperature, ~-123 °C), good dielectric strength (~50 V/µm), and toughness (63 kJ/m3).

Revealing the Effect of Synthesis Conditions on the Structural, Optical, and Antibacterial Properties of Cerium Oxide Nanoparticles.

Cerium oxide nanoparticles were prepared by a precipitation method using Ce(IV) sulphate as precursor dispersed in glycerol with varying synthesis parameters such as temperature or precipitating agent. The structural and morphological characteristics of the obtained nanoparticles were investigated by X-ray diffraction, transmission electron microscopy, and diffuse reflectance spectroscopy. The crystallite size of the nanoparticles varied between 13 and 17 nm. The presence of Ce3+ and Ce4+ was proved by XPS data in the CeO2 samples and the conservation of the fluorite structure was evinced by X-ray diffractograms with a contraction of the lattice parameter, regardless of the size of the nanoparticle. From diffuse reflectance spectra, two band gap energy values for the direct transition were observed. Depending on the synthesis condition, the red shift of gap energy and the blue shift of Urbach energy with increasing content of Ce3+ were ascertained. The antibacterial tests revealed that the cerium oxide nanoparticles show good antimicrobial activity towards the common pathogens Escherichia coli and Staphylococcus aureus.

Effect of calcium stearate as a lubricant and catalyst on the thermal degradation of poly(3-hydroxybutyrate).

Poly(3-hydroxybutyrate) (PHB) is a promising substitute to petroleum-based polymers in packaging and biomedical applications provided that its melt processability and degradability are improved. A new method to control the properties of PHB by using cheap calcium stearate (CS) as a lubricant and decomposition catalyst in melt-mixed PHB-CS compounds was first used. CS is composed of a metallic cation, which promotes PHB degradation, and a hydrophobic anion that improves the compatibility with PHB and processability. An environmentally friendly melt mixing technique was employed to obtain the PHB-CS compounds. Incorporation of 0.5 or 5 wt% CS reduced the melt viscosity and molecular weight of PHB, decreased the melting temperature with up to 5 °C, the crystallization temperature with more than 25 °C, and the degradation temperature with 15 and 40 °C, respectively. In small amounts (0.05 wt%), CS improved the processability and mechanical properties of PHB. In higher amount (0.5 wt%), CS slightly improved the Young's modulus, reduced the tensile strength and enhanced degradation. A better control of thermal and mechanical properties of PHB is, thus, possible by using different CS amount and processing conditions. These results are relevant for PHB application in the context of the global transition to biodegradable packaging.

Tailoring Mesoporous Titania Features by Ultrasound-Assisted Sol-Gel Technique: Effect of Surfactant/Titania Precursor Weight Ratio.

A mesoporous titania structure has been prepared using the ultrasound-assisted sol-gel technique in order to find out a way to tailor its structure. The TiO2 obtained was compared to the same version of titania but synthesized by a conventional sol-gel method with the objective of understanding the effect of ultrasound in the synthesis process. All synthesis experiments were focused on the preparation of a titania photocatalyst. Thus, the anatase photocatalytic active phase of titania was proven by X-ray diffraction. Additionally, the ultrasonation treatment proved to increase the crystallinity of titania samples, being one of the requirements to having good photocatalytic activity for titania. The influence of surfactant/titania precursor weight ratio on the structural (XRD), textural (N2-sorption measurements), morphological (TEM), surface chemistry (FTIR) and optical properties (UVDR) was investigated. It was observed that the crystallite size, specific surface area, band gap energy and even photocatalytic activity was affected by the synergism occurring between cavitation effect and the surfactant/titania precursor weight ratio. The study yielded interesting great results that could be considered for further application of ultrasound to tailor mesoporous titania features via sol-gel soft template synthesis, against conventional sol-gel process.

Phyto-Functionalized Silver Nanoparticles Derived from Conifer Bark Extracts and Evaluation of Their Antimicrobial and Cytogenotoxic Effects.

Silver nanoparticles synthesized using plant extracts as reducing and capping agents showed various biological activities. In the present study, colloidal silver nanoparticle solutions were produced from the aqueous extracts of Picea abies and Pinus nigra bark. The phenolic profile of bark extracts was analyzed by liquid chromatography coupled to mass spectrometry. The synthesis of silver nanoparticles was monitored using UV-Vis spectroscopy by measuring the Surface Plasmon Resonance band. Silver nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy, dynamic light scattering, scanning electron microscopy, energy dispersive X-ray and transmission electron microscopy analyses. The antimicrobial and cytogenotoxic effects of silver nanoparticles were evaluated by disk diffusion and Allium cepa assays, respectively. Picea abies and Pinus nigra bark extract derived silver nanoparticles were spherical (mean hydrodynamic diameters of 78.48 and 77.66 nm, respectively) and well dispersed, having a narrow particle size distribution (polydispersity index values of 0.334 and 0.224, respectively) and good stability (zeta potential values of -10.8 and -14.6 mV, respectively). Silver nanoparticles showed stronger antibacterial, antifungal, and antimitotic effects than the bark extracts used for their synthesis. Silver nanoparticles obtained in the present study are promising candidates for the development of novel formulations with various therapeutic applications.

Citrate-silver nanoparticles and their impact on some environmental beneficial fungi.

Colloidal suspensions of silver nanoparticles (AgNPs) with surface modified by capping with citrate ions were synthesized by chemical reduction method. Transmission and Scanning Electron Microscopy as well as darkfield Optical Microscopy provided information on the nanoparticle morphology, with fine symmetrical grains and log-normal fitted size distribution. Small Angle X-ray Scattering method allowed theoretical confirmation of colloidal silver nanoparticle fine granularity, based on measurements in the native fluid sample. UV-Vis spectrophotometry allowed studying the Localized Surface Plasmon Resonance band versus the stability of the citrate-AgNP sample after storage and after UV-C exposure. The colloidal AgNP impact on Phanerochaete chrysosporium environmental microorganisms was studied by specific biochemical investigations. Silver released from the colloidal suspension of AgNPs was supposed to induce changes in some antioxidant enzymes and in some enzymes of Krebs' cycle. Catalase activity was moderately changed (an increase with over 50%) as well as superoxide dismutase activity, while the diminution of the activities of four dehydrogenases synthesized in the fungus mycelium was emphasized also: a decrease with about 60% for malate dehydrogenase, with over 50% for isocitrate dehydrogenase and succinate dehydrogenase and with about 40% for alpha-ketoglutarate dehydrogenase. These findings suggested the nano-toxicological issues of citrate-AgNPs impact on the environmental beneficial microorganisms.

Pullulan derivative with cationic and hydrophobic moieties as an appropriate macromolecule in the synthesis of nanoparticles for drug delivery.

A new amphiphilic pullulan derivative (DBAP-PO) was obtained by grafting tertiary butyl amine and octanoyl groups on the pullulan backbone as cationic and hydrophobic moieties, respectively. The structural characteristics of the modified polymer were investigated by FT-IR and 1H and 13C NMR spectroscopy. The self-association ability in aqueous solution of DBAP-PO was studied by viscosity and fluorescence methods. The intrinsic viscosity of the polymer was determined by Wolf model. The critical aggregation concentration (CAC) value of 0.028 g/dL, determined by fluorescence measurements in the presence of pyrene, was confirmed by capillary viscosimetry and dynamic laser scattering (DLS). Dialysis method was used to demonstrate the capacity of the pullulan derivative to form spherical nanoparticles (d ~ 200 nm) loaded with model drug, sodium diclofenac (DF) (74% entrapment efficiency). The DF release was sustained and pH-dependent. In vitro cytotoxicity as well as morphological studies conducted on the human skin fibroblasts showed that DBAP-PO/DF nanoparticles do not exhibit cytotoxic effects at the pharmacologically relevant concentration of DF, maintaining the typical morphology of the cells.

Highly efficient and fast removal of colored pollutants from single and binary systems, using magnetic mesoporous silica.

Magnetic mesoporous silica material was tested as adsorbent for removal of two usual colored compounds present in industrial wastewater. The magnetic mesoporous silica was synthesized by modified sol-gel method and characterized from the morpho-textural, structural and magnetic point of view. The specific surface area and the total pore volume indicate a good adsorption capacity of the material, and the obtained saturation magnetization strength value denotes a good magnetic separation from solution. The adsorption capacity of magnetic mesoporous silica increases with the increase of the initial dye concentration, and the removal efficiency of the dyes was dependent on the pH of the solution and decreased with increasing temperature. The pseudo-second-order kinetic model described best the adsorption mechanism, and the maximum adsorption capacities were determined from the Sips isotherm model, being 88.29 mg/g for Congo Red and 208.31 mg/g for Methylene Blue. A complete thermodynamic evaluation was performed, by determining the free energy, enthalpy and entropy, and the result showed a spontaneous and exothermic adsorption process. The recovery and reutilization of the adsorbent were estimated in five cycles of adsorption-desorption, and the results indicated a good stability and reusability of magnetic mesoporous silica. The new magnetic mesoporous silica can be easily separated from solution, via an external magnetic field, and may be effectively applied as adsorbent for elimination of dyes from colored polluted waters.

SiO2-PVA-Fe(acac)3 Hybrid Based Superparamagnetic Nanocomposites for Nanomedicine: Morpho-textural Evaluation and In Vitro Cytotoxicity Assay.

A facile sol-gel route has been applied to synthesize hybrid silica-PVA-iron oxide nanocomposite materials. A step-by-step calcination (processing temperatures up to 400 °C) was applied in order to oxidize the organics together with the iron precursor. Transmission electron microscopy, X-ray diffraction, small angle neutron scattering, and nitrogen porosimetry were used to determine the temperature-induced morpho-textural modifications. In vitro cytotoxicity assay was conducted by monitoring the cell viability by the means of MTT assay to qualify the materials as MRI contrast agents or as drug carriers. Two cell lines were considered: the HaCaT (human keratinocyte cell line) and the A375 tumour cell line of human melanoma. Five concentrations of 10 µg/mL, 30 µg/mL, 50 µg/mL, 100 µg/mL, and 200 µg/mL were tested, while using DMSO (dimethylsulfoxid) and PBS (phosphate saline buffer) as solvents. The HaCaT and A375 cell lines were exposed to the prepared agent suspensions for 24 h. In the case of DMSO (dimethyl sulfoxide) suspensions, the effect on human keratinocytes migration and proliferation were also evaluated. The results indicate that only the concentrations of 100 µg/mL and 200 µg/mL of the nanocomposite in DMSO induced a slight decrease in the HaCaT cell viability. The PBS based in vitro assay showed that the nanocomposite did not present toxicity on the HaCaT cells, even at high doses (200 µg/mL agent).

New insights into human hair: SAXS, SEM, TEM and EDX for Alopecia Areata investigations.

BACKGROUND: Alopecia areata (AA) is a T-cell-mediated autoimmune disease and affects up to 2% of the population. There is a need for a more profound and rigorous understanding of the structure and composition of human hair affected by AA in order to manage this disease. The aim of this article is to understand the effects of AA on the structure and composition of human hair. METHODS: Several physico-chemical investigation methods, such as Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray Spectroscopy (EDX), and microbeam Small Angle X-ray Scattering (SAXS), were used to analyze human hair samples obtained from healthy donors and patients with AA. RESULTS: SEM revealed more severe hair surface defects for the white regrown hair (W-AA) samples. TEM showed the presence of air-like vesicles located in the endocuticle of regrown hair. Analysis of ultrathin sections of W-AA showed the existence of empty vesicles and smaller melanin granules compared to control samples. SAXS demonstrated that unaffected hair of patients with AA (B-AA) and W-AA melanin aggregates are different in their sizes and shapes compared to the control samples. EDX data showed that W-AA elemental composition was significantly different from the other sample groups. Our study showcases promising non-invasive techniques for a better and more accurate understanding of changes in the internal structure and composition of hair affected by AA.

Novel rare earth (RE-La, Er, Sm) metal doped ZnO photocatalysts for degradation of Congo-Red dye: Synthesis, characterization and kinetic studies.

Synthesis and characterization of novel ZnO:RE nanostructured materials doped with 1% rare-earth elements (RE = La, Er, Sm) and their testing for photocatalytic applications were reported. The materials were obtained via electrospining, followed by calcination at 700 °C. The samples were characterized in terms of surface morphology (SEM, TEM), crystalline structure (XRD) and band gap energies. TEM results showed the formation of a unidimensional structure (ZnO) with an average fiber diameter of 600 nm and a morphology consisting of interconnected nanoparticles having dimensions in the range 25-134 nm (ZnO doped with RE). Optical properties were explored by using UV-VIS reflectance spectra and the band gap values were determined with the Kubelka-Munk function (KM) by plotting [F(R∞)hν]2vs. hʋ. The photocatalytic activity was assessed by studying the degradation of a water-soluble anionic dye (Congo-Red) under UV-light irradiation. The data related to photodegradation kinetics were reasonably fitted to the pseudo-first-order kinetic model. Results revealed that the values of the rate constants ranged from 10-3 to 10-2 min-1, depending on the material type and initial dye concentration. In addition, Langmuir-Hinshelwood (LH) model was utilized to explain the kinetics of photodegradation reactions of CR in the presence of (ZnO:Sm) sample. The LH approach suggested that both adsorption and photocatalysis phenomena prevailed in the process of dye removal. Optimal conditions of experiments were determined empirically by employing the gradient method. Thus, a maximal value of color removal efficiency (95.8%) was observed experimentally for the initial dye concentration of 10.7 mg/L and 0.236 g/L catalyst dosage (ZnO:Sm). Furthermore, a successful recovery of the spent catalyst was accomplished by thermal activation.

Antioxidant/Antibacterial Electrospun Nanocoatings Applied onto PLA Films.

Polylactic acid (PLA) films were coated by coaxial electrospinning with essential and vegetable oils (clove and argan oils) and encapsulated into chitosan, in order to combine the biodegradability and mechanical properties of PLA substrates with the antimicrobial and antioxidant properties of the chitosan⁻oil nanocoatings. It has been established that the morphology of the electrospun nanocoatings mainly depend on the average molecular weight (MW) of chitosan. Oil beads, encapsulated into the main chitosan nanofibers, were obtained using high-MW chitosan (Chit-H). Oil encapsulated in chitosan naoparticles resulted when low-MW chitosan (Chit-L) was used. The coating layer, with a thickness of 100 ± 20 nm, had greater roughness for the samples containing Chit-H compared with the samples containing Chit-L. The coated PLA films had higher antibacterial activity when the nanocoating contained clove oil rather than when argan oil was used, for both types of chitosan. Nanocoatings containing Chit-H had higher antibacterial activity compared with those containing Chit-L, for both types of oil tested, due to the larger surface area of the rougher nanoscaled morphology of the coating layer that contained Chit-L. The chitosan⁻clove oil combination had higher antioxidant activity compared to the simple chitosan nanocoating, which confirmed their synergistic activities. The low activity of systems containing argan oil was explained by big differences between their chemical composition and viscosity.

Low-molecular-weight sulfonated chitosan as template for anticoagulant nanoparticles.

PURPOSE: In this work, low-molecular-weight sulfoethyl chitosan (SECS) was used as a model template for the generation of silver core-shell nanoparticles with high potential as anticoagulants for medical applications. MATERIALS AND METHODS: SECS were synthesized by two reaction pathways, namely Michael addition and a nucleophilic substitution with sodium vinylsulfonate or sodium 2-bromoethanesulfonate (NaBES). Subsequently, these derivatives were used as reducing and capping agents for silver nanoparticles in a microwave-assisted reaction. The formed silver-chitosan core-shell particles were further surveyed in terms of their anticoagulant action by different coagulation assays focusing on the inhibition of either thrombin or cofactor Xa. RESULTS: In-depth characterization revealed a sulfoalkylation of chitosan mainly on its sterically favored O6-position. Moreover, comparably high average degrees of substitution with sulfoethyl groups (DSSE) of up to 1.05 were realized in reactions with NaBES. The harsh reaction conditions led to significant chain degradation and consequently, SECS exhibits masses of <50 kDa. Throughout the following microwave reaction, stable nanoparticles were obtained only from highly substituted products because they provide a sufficient charge density that prevented particles from aggregation. High-resolution transmission electron microscopy images reveal that the silver core (diameter ~8 nm) is surrounded by a 1-2 nm thick SECS layer. These core-shell particles and the SECS itself exhibit an inhibiting activity, especially on cofactor Xa. CONCLUSION: This interesting model system enabled the investigation of structure-property correlations in the course of nanoparticle formation and anticoagulant activity of SECS and may lead to completely new anticoagulants on the basis of chitosan-capped nanoparticles.