Pd nanoparticles embedded in nanolignin (Pd@LNP) as a water dispersible catalytic nanoreactor for Cr(VI), 4-nitrophenol reduction and CC coupling reactions

The use of water-dispersible and sustainable Pd nanocatalysts to reduce toxic heavy metal ions and catalyze important organic reactions has profound significance for the environmental remediation and the catalytic industry. In this work, a novel water-dispersible and recyclable Pd@LNPs nanoreactor composed of Pd nanoparticle cluster core and LNPs shell was developed in microwave reactor in aqueous solution. It turned out that Pd nanoparticles grew uniformly and stably inside LNPs nanosphere due to the coordinated binding and interaction between Pd and the functional groups in LNPs, which was significantly different from surface loading. The green and biodegradable LNPs nanospheres are not only used as reducing agents for Pd (II) and nanocarriers, but also act as individual nanocontainers to provide favorable sites for reactions and effectively control the entry and release of reactants and products. Furthermore, the excellent and efficient catalytic properties of Pd@LNPs were exhibited by CC coupling reactions and the reduction of Cr(VI) and 4-nitrophenol. The Pd@LNPs prepared in this study have the advantages of excellent dispersion, great recyclability, high turnover frequency and better green sustainability metrics. It will have a great significance for the development of the potential high-value of lignin and the progress in the field of bio-nanocatalysts.

Fluid Mechanics of Droplet Spreading of Chitosan/PVA-Based Spray Coating Solution on Banana Peels with Different Wettability

The spreading behavior of a coating solution is an important factor in determining the effectiveness of spraying applications. It determines how evenly the droplets spread on the substrate surface and how quickly they form a uniform film. Fluid mechanics principles govern it, including surface tension, viscosity, and the interaction between the liquid and the solid surface. In our previous work, chitosan (CS) film properties were successfully modified by blending with polyvinyl alcohol (PVA). It was shown that the mechanical strength of the composite film was significantly improved compared to the virgin CS. Here we propose to study the spreading behavior of CS/PVA solution on fresh bananas. The events upon droplet impact were captured using a high-speed camera, allowing the identification of outcomes as a function of velocity at different surface wettabilities (wetting and non-wetting) on the banana peels. The mathematical model to predict the maximum spreading factor, βmax, was governed by scaling law analysis using fitting experimental data to identify patterns, trends, and relationships between βmax and the independent variables, Weber (We) numbers, and Reynolds (Re) numbers. The results indicate that liquid viscosity and surface properties affect the droplet's impact and spreading behavior. The Ohnesorge (Oh) numbers significantly influenced the spreading dynamics, while the banana's surface wettability minimally influenced spreading. The prediction model reasonably agrees with all the data in the literature since the R2 = 0.958 is a powerful goodness-of-fit indicator for predicting the spreading factor. It scaled with βmax=a+0.04We.Re1/3, where the "a" constants depend on Oh numbers.

Microwave-Assisted Synthesis of Pd Nanoparticles into Wood Block (Pd@wood) as Efficient Catalyst for 4-Nitrophenol and Cr(VI) Reduction

Palladium (Pd) nanoparticle catalysis has attracted increasing attention due to its efficient catalytic activity and its wide application in environmental protection and chemical synthesis. In this work, Pd nanoparticles (about 71 nm) were synthesized in aqueous solution by microwave-assisted thermal synthesis and immobilized in beech wood blocks as Pd@wood catalysts. The wood blocks were first hydrothermally treated with 10% NaOH solution to improve the internal structure and increase their porosity, thereby providing favorable attachment sites for the formed Pd nanoparticles. The stable deposition of Pd nanoparticle clusters on the internal channels of the wood blocks can be clearly observed. In addition, the catalytic performance of the prepared Pd@wood was investigated through two model reactions: the reduction of 4-nitrophenol and Cr(VI). The Pd@wood catalyst showed 95.4 g-1 s-1 M-1 of normalized rate constant knorm and 2.03 min-1 of the TOF, respectively. Furthermore, Pd nanoparticles are integrated into the internal structure of wood blocks by microwave-assisted thermal synthesis, which is an effective method for wood functionalization. It benefits metal nanoparticle catalysis in the synthesis of fine chemicals as well as in industrial wastewater treatment.

A continuous flow mode with a scalable tubular reactor for the green preparation of stable alkali lignin nanoparticles assisted by ultrasound

Lignin nanoparticles (LNPs) have become a hot topic recently because of their improved physicochemical properties and the excellent integration into various industrial sectors compared to lignin. However, the green large-scale production of stable LNPs severely restricts the high-value applications of LNPs. In this work, a simple and potentially scalable continuous-flow mode setup with a tubular flow reactor was designed for the green preparation of stable alkali LNPs assisted by ultrasound. When the flow rates of lignin solution and nitric acid solution were 8.00 mL/min and 2.67 mL/min respectively, and the length of the tube was 5.5 m, the average residence time of mixed solution was 62.2 s in the tubular reactor. Spheroid nanoparticles with an average size of 97.2 nm were obtained under this optimized condition. Furthermore, the results showed a better control of the mixing compared to the batch process, resulting in a homogeneous distribution of smaller particle sizes thus improving stability and UV-blocking properties. This is attributed to the better mixing and excellent mass transfer characteristics in the tube, which provides favorable conditions for the full contact and uniform dispersion of the mixed solution. More importantly, continuous flow mode makes it possible to prepare LNPs with excellent physicochemical properties on a large scale, which will bring great opportunities for the industrial production and application of LNPs.

Purification of Natural Pigments Violacein and Deoxyviolacein Produced by Fermentation Using Yarrowia lipolytica

Violacein and deoxyviolacein are bis-indole pigments synthesized by a number of microorganisms. The present study describes the biosynthesis of a mixture of violacein and deoxyviolacein using a genetically modified Y. lipolytica strain as a production chassis, the subsequent extraction of the intracellular pigments, and ultimately their purification using column chromatography. The results show that the optimal separation between the pigments occurs using an ethyl acetate/cyclohexane mixture with different ratios, first 65:35 until both pigments were clearly visible and distinguishable, then 40:60 to create a noticeable separation between them and recover the deoxyviolacein, and finally 80:20, which allows the recovery of the violacein. The purified pigments were then analyzed by thin-layer chromatography and nuclear magnetic resonance.

Additive manufacturing of microstructured reactors for organometallic catalytic reactions

The use of Additive Manufacturing for the fabrication of chemical reactors for flow chemistry is a promising field as it can lead to several improvements over more standard equipment. In this work, two different reactors were fabricated and compared: a Honeycomb monolith reactor with straight channels and a Periodic Open Cell Structure reactor. The Honeycomb monolith reactor was used as an example of a standard reactor (not necessarily additive manufactured) while the Periodic Open Cell Structure is a promising new type of reactor, which improves some key features, such as contact surface area and porosity. The two reactors were manufactured by Stereolithography technology with a high temperature resin and their internal surfaces were chemically activated by the grafting of palladium. For the surface activation, a two-step procedure was developed, firstly using NaOH and in a second step an aqueous solution of Na₂PdCl₄. After activation, a heterogeneous catalytic reaction was used to characterize the performance of the two fabricated reactors. The chosen reaction was the Suzuki-Miyaura reaction, which is commonly used in the pharmaceutical industry. The experimental results showed that, for equal contact surface area, the new designed reactor had better performance compared to the standard geometry.

Modification of Physio-Mechanical Properties of Chitosan-Based Films via Physical Treatment Approach

The premise of this work is the modification of the properties of chitosan-based film for possible use in food packaging applications. The biofilm was prepared via thermal and mechanical treatment through blending polymers with chitosan using Polyvinyl Alcohol (PVA) and loading different types of chemical agents, i.e., citric acid (CA), succinic acid (SA), and tetraethoxysilane (TEOS). The modification was carried out under high-speed homogenization at elevated temperature to induce physical cross-linkage of chitosan polymer chains without a catalyst. The findings showed that PVA improved the chitosan films' Tensile strength (TS) and elongation at break (Eb). The presence of chemicals caused an increase in the film strength for all samples prepared, in which a 5% w/w of chemical in the optimum composition CS/PVA (75/25) provided the maximum strength, namely, 33.9 MPa, 44.0 MPa, and 41.9 MPa, for CA-5, SA-5, and TEOS-5, respectively. The chemical agents also increased the water contact angles for all tested films, indicating that they promoted hydrophobicity. The chemical structure analysis showed that, by incorporating three types of chemical agents into the CS/PVA blend films, no additional spectral bands were found, indicating that no covalent bonds were formed. The thermal properties showed enhancement in melting peak and degradation temperature of the blend films, compared to those without chemical agents at the optimum composition. The X-ray diffraction patterns exhibited that PVA led to an increasing crystallization tendency in the blend films. The morphological observation proved that no irregularities were detected in CS/PVA blend films, representing high compatibility with both polymers.

Metal vs. Metal-Free Catalysts for Oxidation of 5-Hydroxymethylfurfural and Levoglucosenone to Biosourced Chemicals

Lignocellulosic feedstocks, such as forestry biomass and agricultural crop residues, can be utilized to generate biofuels and biochemicals. Converting these organic waste materials into biochemicals is widely regarded as a remedial approach to develop a sustainable, clean, and green energy source. Nevertheless, are these methods sustainable and clean? Prior studies have shown that most such conversions use metals - including heavy metals or noble metals - as catalysts. In addition to the fact that many metals (e. g., aluminum, cobalt, titanium, platinum) have been listed as critical minerals, these methods suffer from high cost, deactivation, and leakage problems and the release of toxic wastes. This Review summarizes catalytic methods using metal and metal-free catalysts for the oxidation of the platform molecules 5-hydroxymethylfurfural and levoglucosenone and demonstrates the potential and effectiveness of metal-free catalysts.

Cellulosic/Polyvinyl Alcohol Composite Hydrogel: Synthesis, Characterization and Applications in Tissue Engineering

The biomedical field still requires composite materials for medical devices and tissue engineering model design. As part of the pursuit of non-animal and non-proteic scaffolds, we propose here a cellulose-based material. In this study, 9%, 18% and 36% dialdehyde-functionalized microcrystalline celluloses (DAC) were synthesized by sodium periodate oxidation. The latter was subsequently coupled to PVA at ratios 1:2, 1:1 and 2:1 by dissolving in N-methyl pyrrolidone and lithium chloride. Moulding and successive rehydration in ethanol and water baths formed soft hydrogels. While oxidation effectiveness was confirmed by dialdehyde content determination for all DAC, we observed increasing hydrolysis associated with particle fragmentation. Imaging, FTIR and XDR analysis highlighted an intertwined DAC/PVA network mainly supported by electrostatic interactions, hemiacetal and acetal linkage. To meet tissue engineering requirements, an interconnected porosity was optimized using 0-50 µm salts. While the role of DAC in strengthening the hydrogel was identified, the oxidation ratio of DAC showed no distinct trend. DAC 9% material exhibited the highest indirect and direct cytocompatibility creating spheroid-like structures. DAC/PVA hydrogels showed physical stability and acceptability in vivo that led us to propose our DAC 9%/PVA based material for soft tissue graft application.

Gold, Silver, and Iron Oxide Nanoparticle Incorporation into Silk Hydrogels for Biomedical Applications: Elaboration, Structure, and Properties

Silk fibroin (SF) is a versatile material with biodegradable and biocompatible properties, which make it fit for broad biomedical applications. In this context, the incorporation of nanosized objects into SF allows the development of a variety of bionanocomposites with tailored properties and functions. Herein, we report a thorough investigation on the design, characterization, and biological evaluation of SF hydrogels incorporating gold, silver, or iron oxide nanoparticles. The latter are synthesized in aqueous media using a biocompatible ligand allowing their utilization in various biomedical applications. This ligand seems to play a pivotal role in nanoparticle dispersion within the hydrogel. Results show that the incorporation of nanoparticles does not greatly influence the mechanism of SF gelation and has a minor impact on the mechanical properties of the so-obtained bionanocomposites. By contrast, significant changes are observed in the swelling behavior of these materials, depending on the nanoparticle used. Interestingly, the main characteristics of these bionanocomposites, related to their potential use for biomedical purposes, show the successful input of nanoparticles, including antibacterial properties for gold and silver nanoparticles and magnetic properties for iron oxide ones.

Lignin Nanoparticles and Their Nanocomposites

Lignin nanomaterials have emerged as a promising alternative to fossil-based chemicals and products for some potential added-value applications, which benefits from their structural diversity and biodegradability. This review elucidates a perspective in recent research on nanolignins and their nanocomposites. It summarizes the different nanolignin preparation methods, emphasizing anti-solvent precipitation, self-assembly and interfacial crosslinking. Also described are the preparation of various nanocomposites by the chemical modification of nanolignin and compounds with inorganic materials or polymers. Additionally, advances in numerous potential high-value applications, such as use in food packaging, biomedical, chemical engineering and biorefineries, are described.

Heterogeneous deacetylation reaction of chitin under low-frequency ultrasonic irradiation

Low-frequency ultrasonic irradiation was employed as a low cost technique for chitin's deacetylation at a relatively low-temperature range (below 70 °C) and a short reaction times (up to 120 min). Eley-Rideal mechanism and the power-law model were carried out to describe the mechanism of the reaction. The results indicated that the produced chitosan deacetylation degree (DD) was up to 87.73% under the optimum conditions compared to 66.82% using the conventional one (thermo-alkaline process). The Fourier Transform Infrared (FTIR) observations of the produced chitosan presented the same fingerprint as the commercial chitosan, X-Ray Diffraction (XRD), and Differential Scanning Calorimetry (DSC) studies show that the DD induced a lousy impact on the chitosan's thermal degradation and crystallinity index. This work effectively demonstrates that chitin's deacetylation under low-frequency ultrasonic irradiation provides a green process to produce chitosan, and the power-law model, r_DD = k₁(C_R1-NH2)^α; k₁=Aexp-E_aRT, is an excellent model to describe the complex reaction.

Studies of the potential of a native natural biosorbent for the elimination of an anionic textile dye Cibacron Blue in aqueous solution

This work is devoted to the adsorption of Cibacron Blue (CB) an anionic textile dye, on bean peel (BP) an agricultural waste with neither activation nor carbonization. The adsorption was realized in batch configuration at ambient temperature in acidic medium. The adsorbent was characterized by FTIR, SEM and BET analyses; the equilibrium isotherms and kinetics were also studied. It has been found that this waste could be used as a low-cost biosorbent for CB elimination under optimal working conditions. The rate of CB elimination reaches 95% on bean bark (3.6 g/L) at pH 2.2 and a reject concentration of 25 mg/L. The pseudo-second-order describes suitably the experimental data and the external diffusion is the rate-determining step. The Freundlich isotherm fits better the CB adsorption with a correlation coefficient (R²) of 0.94 and an RMSE = 1.5115. The negative enthalpy (ΔH) and free enthalpy (ΔG°) indicate a physical and spontaneous nature of the CB biosorption onto the biomaterial.

Silk Polymers and Nanoparticles: A Powerful Combination for the Design of Versatile Biomaterials

Silk fibroin (SF) is a natural protein largely used in the textile industry but also in biomedicine, catalysis, and other materials applications. SF is biocompatible, biodegradable, and possesses high tensile strength. Moreover, it is a versatile compound that can be formed into different materials at the macro, micro- and nano-scales, such as nanofibers, nanoparticles, hydrogels, microspheres, and other formats. Silk can be further integrated into emerging and promising additive manufacturing techniques like bioprinting, stereolithography or digital light processing 3D printing. As such, the development of methodologies for the functionalization of silk materials provide added value. Inorganic nanoparticles (INPs) have interesting and unexpected properties differing from bulk materials. These properties include better catalysis efficiency (better surface/volume ratio and consequently decreased quantify of catalyst), antibacterial activity, fluorescence properties, and UV-radiation protection or superparamagnetic behavior depending on the metal used. Given the promising results and performance of INPs, their use in many different procedures has been growing. Therefore, combining the useful properties of silk fibroin materials with those from INPs is increasingly relevant in many applications. Two main methodologies have been used in the literature to form silk-based bionanocomposites: in situ synthesis of INPs in silk materials, or the addition of preformed INPs to silk materials. This work presents an overview of current silk nanocomposites developed by these two main methodologies. An evaluation of overall INP characteristics and their distribution within the material is presented for each approach. Finally, an outlook is provided about the potential applications of these resultant nanocomposite materials.

Nanofluid to Nanocomposite Film: Chitosan and Cellulose-Based Edible Packaging

Chitosan (CH)-based materials are compatible to form biocomposite film for food packaging applications. In order to enhance water resistance and mechanical properties, cellulose can be introduced to the chitosan-based film. In this work, we evaluate the morphology and water resistance of films prepared from chitosan and cellulose in their nanoscale form and study the phenomena underlying the film formation. Nanofluid properties are shown to be dependent on the particle form and drive the morphology of the prepared film. Film thickness and water resistance (in vapor or liquid phase) are clearly enhanced by the adjunction of nanocrystalline cellulose.

Endosomal Confinement of Gold Nanospheres, Nanorods, and Nanoraspberries Governs Their Photothermal Identity and Is Beneficial for Cancer Cell Therapy

Gold nanoparticles can act as photothermal agents to generate local tumor heating and subsequent depletion upon laser exposure. Herein, photothermal heating of four gold nanoparticles and the resulting induced cancer cell death are systematically assessed, within extra- or intracellular localizations. Two state-of-the-art gold nanorods are compared with small nanospheres (single-core) and nanoraspberries (multicore). Heat generation is measured in water dispersion and in cancer cells, using lasers at wavelengths of 680, 808, and 1064 nm, covering the entire range used in photothermal therapy, defined as near infrared first (NIR-I) and second (NIR-II) windows, with NIR-II offering more tissue penetration. When dispersed in water, gold nanospheres provide no significant heating, gold nanorods are efficient in NIR-I, and only gold nanoraspberries are still heating in NIR-II. However, in cells, due to endosomal confinement, all nanoparticles present an absorption red-shift translating visible and NIR-I absorbing nanoparticles into effective NIR-I and NIR-II nanoheaters, respectively. The gold nanorods then become competitive with the multicore nanoparticles (nanoraspberries) in NIR-II. Similarly, once in cells, gold nanospheres can be envisaged for NIR-I heating. Remarkably, nanoraspberries are efficient nanoheaters, whatever the laser applied, and the extra- versus intra-cellular localization demonstrates treatment versatility.

A gram scale selective oxidation of 5-hydroxymethylfurfural to diformylfuran in the presence of oxone and catalyzed by 2-iodobenzenesulfonic acid

In the present work, an alternative system of 5-hydroxymethylfurfural (HMF) oxidation was studied, in an attempt to avoid the use of expensive metal catalysts, polluting systems and high pressures.

Synthesis and activation of an iron oxide immobilized drug-mimicking reporter under conventional and pulsed X-ray irradiation conditions

An efficient nano-sized delivery system is presented here allowing the immobilized, picolinium-tethered organic ligand to be released by X-ray irradiation. A marked difference was observed in the fragmentation efficiency by using conventional Cs-137 vs. pulsed sources.

The nano-sized delivery system allowed releasing complex organic ligands by X-ray irradiation. Marked difference was observed in the release efficiency by using conventional Cs-137 vs. pulsed sources.

Cellulose Nanocrystals to Improve Stability and Functional Properties of Emulsified Film Based on Chitosan Nanoparticles and Beeswax

The framework of this work was to develop an emulsion-based edible film based on a chitosan nanoparticle matrix with cellulose nanocrystals (CNCs) as a stabilizer and reinforcement filler. The chitosan nanoparticles were synthesized based on ionic cross-linking with sodium tripolyphosphate and glycerol as a plasticizer. The emulsified film was prepared through a combination system of Pickering emulsification and water evaporation. The oil-in-water emulsion was prepared by dispersing beeswax into an aqueous colloidal suspension of chitosan nanoparticles using high-speed homogenizer at room temperature. Various properties were characterized, including surface morphology, stability, water vapor barrier, mechanical properties, compatibility, and thermal behaviour. Experimental results established that CNCs and glycerol improve the homogeneity and stability of the beeswax dispersed droplets in the emulsion system which promotes the water-resistant properties but deteriorates the film strength at the same time. When incorporating 2.5% w/w CNCs, the tensile strength of the composite film reached the maximum value, 74.9 MPa, which was 32.5% higher than that of the pure chitosan film, while the optimum one was at 62.5 MPa, and was obtained by the addition of 25% w/w beeswax. All film characterizations demonstrated that the interaction between CNCs and chitosan molecules improved their physical and thermal properties.

Ultrasonic Irradiation Coupled with Microwave Treatment for Eco-friendly Process of Isolating Bacterial Cellulose Nanocrystals

The isolation of crystalline regions from fibers cellulose via the hydrolysis route generally requires corrosive chemicals, high-energy demands, and long reaction times, resulting in high economic costs and environmental impact. From this basis, this work seeks to develop environment-friendly processes for the production of Bacterial Cellulose Nanocrystals (BC-NC). To overcome the aforementioned issues, this study proposes a fast, highly-efficient and eco-friendly method for the isolation of cellulose nanocrystals from Bacterial Cellulose, BC. A two-step processes is considered: (1) partial depolymerization of Bacterial Cellulose (DP-BC) under ultrasonic conditions; (2) extraction of crystalline regions (BC-NC) by treatment with diluted HCl catalyzed by metal chlorides (MnCl₂ and FeCl₃.6H₂O) under microwave irradiation. The effect of ultrasonic time and reactant and catalyst concentrations on the index crystallinity (CrI), chemical structure, thermal properties, and surface morphology of DP-BC and BC-NC were evaluated. The results indicated that the ultrasonic treatment induced depolymerization of BC characterized by an increase of the CrI. The microwave assisted by MnCl₂-catalyzed mild acid hydrolysis enhanced the removal of the amorphous regions, yielding BC-NC. A chemical structure analysis demonstrated that the chemical structures of DP-BC and BC-NC remained unchanged after the ultrasonic treatment and MnCl₂-catalyzed acid hydrolysis process.

Diazonium Salt-Based Surface-Enhanced Raman Spectroscopy Nanosensor: Detection and Quantitation of Aromatic Hydrocarbons in Water Samples

Here, we present a surface-enhanced Raman spectroscopy (SERS) nanosensor for environmental pollutants detection. This study was conducted on three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BaP), fluoranthene (FL), and naphthalene (NAP). SERS substrates were chemically functionalized using 4-dodecyl benzenediazonium-tetrafluoroborate and SERS analyses were conducted to detect the pollutants alone and in mixtures. Compounds were first measured in water-methanol (9:1 volume ratio) samples. Investigation on solutions containing concentrations ranging from 10⁻⁶ g L⁻¹ to 10⁻³ g L⁻¹ provided data to plot calibration curves and to determine the performance of the sensor. The calculated limit of detection (LOD) was 0.026 mg L⁻¹ (10⁻⁷ mol L⁻¹) for BaP, 0.064 mg L⁻¹ (3.2 × 10⁻⁷ mol L⁻¹) for FL, and 3.94 mg L⁻¹ (3.1 × 10⁻⁵ mol L⁻¹) for NAP, respectively. The correlation between the calculated LOD values and the octanol-water partition coefficient (K_ow) of the investigated PAHs suggests that the developed nanosensor is particularly suitable for detecting highly non-polar PAH compounds. Measurements conducted on a mixture of the three analytes (i) demonstrated the ability of the developed technology to detect and identify the three analytes in the mixture; (ii) provided the exact quantitation of pollutants in a mixture. Moreover, we optimized the surface regeneration step for the nanosensor.

Versatile “click” synthesis of 1-hydroxy-1,1-methylenebisphosphonic acids with thioalkoxy substituents for the preparation of stable gold nanoparticles

Click synthesis of pegylated bisphosphonates for one pot preparation of stable gold nanoparticles.

Magnetic nano-organocatalysts: impact of surface functionalization on catalytic activity

Nano-organocatalysts were synthesized using controlled click chemistry and studied in aldolization and Michael addition reactions. It was shown that small modifications of the nanosurface can have a drastic effect on the catalysis.

Immobilized Pd on magnetic nanoparticles bearing proline as a highly efficient and retrievable Suzuki–Miyaura catalyst in aqueous media

Immobilized Pd on magnetic nanoparticles bearing proline as a highly efficient and retrievable Suzuki–Miyaura catalyst in aqueous media.

One pot microwave assisted synthesis of bisphosphonate alkene capped gold nanoparticles

One pot microwave assisted synthesis of bisphosphonate alkene capped gold nanoparticles.

Nanoparticles under the light: click functionalization by photochemical thiol-yne reaction, towards double click functionalization

A light click away: The first application of the thiol-yne reaction to nanoparticle functionalization is described (see figure). This metal-free click chemistry approach is compatible with the addition of various molecules at the surface and can be combined with CuAAC methodology to perform chemoselective double functionalization.

Benzyl(methyl)phosphinic acid

The title compound, C₈H₁₁O₂P, is a phosphinic compound with a tetra­coordinate penta­valent P atom. The phosphinic function plays a predominant role in the cohesion of the crystal structure, both by forming chains along the b axis via strong inter­molecular O—H⋯O hydrogen bonds and by cross-linking these chains perpendicularly via weak inter­molecular C—H⋯O hydrogen bonds, generating a two-dimensional network parallel to (001).

Study of bisphosphonates by matrix-assisted laser desorption/ionization mass spectrometry--influence of alkali atoms on fragmentation patterns

1-hydroxymethylene-1,1-bisphosphonic acids (or bisphosphonates) are compounds that have interesting pharmacological applications. However, few mass spectrometric investigations have been carried out to determine their fragmentation patterns. Herein, we evaluated different matrices for the study by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) of the formation and fragmentation of the protonated, the cationized (MNa+ and MK+) and the deprotonated bisphosphonates. Some in-source fragmentations were observed both in positive and in negative ion modes. The fragmentation patterns obtained in post-source decay mode are also discussed. In contrast to previous electrospray ionization/multi-stage mass spectrometry (ESI-MSn) studies, some new fragmentation pathways were deduced and the effects of alkali ions on the fragmentation patterns were shown. The results summarized here completed the data previously recorded by ESI-MSn and could be used for the characterization of bisphosphonates as alkali complexes in biological mixtures.

Hydronium (3-oxo-1-phosphono-1,3-dihydroisobenzofuran-1-yl)phosphonate

In the title compound, H₃O⁺·C₈H₇O₈P₂⁻, the anions form inversion dimmers by way of pairs of O—H⋯O hydrogen bonds involving the phospho­nic functions and via the hydro­nium cation. Further O—H⋯O links involving the hydronium cation play a prominant part in the cohesion of the crystal structure by building bridges between bis­phospho­nate pairs, forming infinite ribbons along the b-axis direction and by cross-linking these ribbons perpendicularly along the a-axis direction, forming an infinite three-dimensional hydrogen-bond network. The benzene ring and the C=O atoms of the furan ring are disordered over two sets of positions of equal occupancy.

Electrospray tandem mass spectrometry of alendronate analogues: fingerprints for characterization of new potential prodrugs

1-hydroxymethylene-1,1-bisphosphonic acids (HMBPs) are important drugs for the treatment of a variety of bone diseases. Since these compounds have no chromophore, their detection is challenging and mass spectrometry (MS) appears to be an appropriate sensitive tool. Our work deals with the analysis by electrospray ionization tandem mass spectrometry (ESI-MSn) of the well-known nitrogen-containing HMBP alendronate and of three analogues, considered as potential prodrugs. These four molecules share a common structure with different protecting groups on the phosphonic acid and on the amine functions. We describe the dissociation mechanisms of nitrogen-containing HMBPs in positive ion mode and we compare, in negative ion mode, our results with literature data. In both modes, the dissociations are essentially losses of ROH, and of phosphorus-containing species (HPO2, ROP(OH)2 and ROPO(OH)2), where R=H, C6H5, or CH3OC6H5. These fingerprints will be of great value for differentiating alendronate from its potential prodrugs in complex biological mixtures.

Fragmentation patterns of new esterified and unesterified aromatic 1-hydroxymethylene-1, 1-bisphosphonic acids by ESI-MSn

1-Hydroxymethylene-1,1-bisphosphonic acids (HMBPs) are compounds that have interesting pharmacological applications. Unfortunately few studies exist on their analyses by mass spectrometry (MS). In this work, we have analyzed new aromatic HMBPs and their prodrugs with electrospray tandem mass spectrometry (ESI-MS(n)). We describe, for the first time, a complete study of fragmentation patterns, in both positive and negative-ion modes. In positive mode, the cation dissociations are mainly elimination of water and phosphorus fragments. In negative mode, losses of ROH (R==H, C(6)H(5), CH(3)OC(6)H(5)) and HPO(2) were observed. The results have revealed specific structural fingerprints for the screening of these compounds in complex biological mixtures.

Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA

In the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethylamine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies.

Biophysical characterization of an integrin-targeted lipopolyplex gene delivery vector

Nonviral gene delivery vectors now show good therapeutic potential: however, detailed characterization of the composition and macromolecular organization of such particles remains a challenge. This paper describes experiments to elucidate the structure of a ternary, targeted, lipopolyplex synthetic vector, the LID complex. This consists of a lipid component, Lipofectin (L) (1:1 DOTMA:DOPE), plasmid DNA (D), and a dual-function, cationic peptide component (I) containing DNA condensation and integrin-targeting sequences. Fluorophore-labeled lipid, peptide, and DNA components were used to formulate the vector, and the stoichiometry of the particles was established by fluorescence correlation spectroscopy (FCS). The size of the complex was measured by FCS, and the sizes of LID, L, LD, and ID complexes were measured by dynamic light scattering (DLS). Fluorescence quenching experiments and freeze-fracture electron microscopy were then used to demonstrate the arrangement of the lipid, peptide, and DNA components within the complex. These experiments showed that the cationic portion of the peptide, I, interacts with the plasmid DNA, resulting in a tightly condensed DNA-peptide inner core; this is surrounded by a disordered lipid layer, from which the integrin-targeting sequence of the peptide partially protrudes.