Wide Range Of Molecular Weights Research Articles

Segmental mobility in linear polylactides of various molecular weights

In this work we synthesized and studied a series of linear polylactides (PLA) with a fixed L/d -lactide stereoisomer ratio, covering together the wide range of molecular weights, Mn, from ∼6 to ∼80 kg/mol. The basic aims are the segmental mobility mapping, in terms of time scale and fragility, the recording of the Mn dependences of the glass transition temperature and fragility, and, finally, the comparison with corresponding findings from the literature. Obviously, the direct Mn effects on Tg are assessed by preserving PLA at the amorphous state, i.e., via melting and relatively fast cooling. The segmental mobility is studied by conventional and temperature modulated calorimetry, whereas the molecular dynamics is assessed employing the technique of broadband dielectric spectroscopy in combination with proper critical analysis and evaluation routes. The calorimetric and dielectric Tg(Mn) trends were found consistent between each other as well as with previous findings in similar systems, both with respect to experimental findings and theoretic predictions for PLAs of similar L/D ratio. The Mn threshold of entanglements seems to lay between 13 and 28 kg/mol. The fragility index of the α relaxation, i.e., the dielectric analogue of the glass transition, exhibits a similar dependence to that of Tg(Mn). When decreasing Mn to very low values, the high fragility (∼150) drops down to 0 (Mñ6 kg/mol), denoting the vanishing of the polymer chains’ cooperativity. Qualitatively interesting alternations are recorded in the dielectric strength of the α relaxation and the relaxation times width. The effects are discussed in terms of the various parameters co-affecting the polymer dynamics, namely, chain lengths, free volume and dynamical heterogeneities.

Non-Coagulant Spinning of High-Strength Fibers from Homopolymer Polyacrylonitrile Synthesized via Anionic Polymerisation.

The rheological properties, spinnability, and thermal-oxidative stabilization of high-molecular-weight linear polyacrylonitrile (PAN) homopolymers (molecular weights Mη = 90-500 kg/mol), synthesized via a novel metal-free anionic polymerization method, were investigated to reduce coagulant use, enable solvent recycling, and increase the carbon yield of the resulting carbon fibers. This approach enabled the application of the mechanotropic (non-coagulating) spinning method for homopolymer PAN solutions in a wide range of molecular weights and demonstrated the possibility of achieving a high degree of fiber orientation and reasonable mechanical properties. Rheological analysis revealed a significant increase in solution elasticity (G') with increasing molecular weight, facilitating the choice of optimal deformation rates for effective chain stretching prior to strain-induced phase separation during the eco-friendly spinning of concentrated solutions without using coagulation baths. The possibility of collecting ~80 wt% of the solvent at the first stage of spinning from the as-spun fibers was shown. Transparent, defect-free fibers with a tensile strength of up to 800 MPa and elongation at break of about 20% were spun. Thermal treatment up to 1500 °C yielded carbon fibers with a carbon residue of ~50 wt%, in contrast to ~35 wt% for industrial radically polymerized PAN carbonized under the same conditions.

Rubber Oxygenase Degradation Assay by UV-Labeling and Gel Permeation Chromatography.

A versatile and robust end-group derivatization approach using oximes has been developed for the detection of oxidative degradation of synthetic polyisoprenes and polybutadiene. This method demonstrates broad applicability, effectively monitoring degradation across a wide molecular weight range through ultraviolet (UV)-detection coupled to gel permeation chromatography. Importantly, it enables the effective monitoring of degradation via derivatization-induced UV-maximum shifts, even in the presence of an excess of undegraded polyene, overcoming limitations previously reported with refractive index detectors. Notably, this oxime-based derivatization methodology is used in enzymatic degradation experiments of synthetic polyisoprenes characterized by a cis: trans ratio with the rubber oxygenase LcpK30. It reveals substantial UV absorption in derivatized enzymatic degradation products of polyisoprene with molecular weights exceeding 1000g mol-1 - an unprecedented revelation for this enzyme's activity on such synthetic polyisoprenes. This innovative approach holds promise as a valuable tool for advancing research into the degradation of synthetic polyisoprenes and polybutadiene, particularly under conditions of low organocatalytic or enzymatic degradation activity. With its broad applicability and capacity to reveal previously hidden degradation processes, it represents a noteworthy contribution to sustainable polymer chemistry.

Unraveling the characteristics of dissolved organic matter removed by aluminum species based on FT-ICR MS analysis

Given the complexity of dissolved organic matter (DOM) and its interactions with coagulant chemicals, the mechanisms of DOM removal by aluminum (Al) coagulants remains a significant unknown. In this study, six test waters containing DOM with molecular weight (MW, <1 kDa, 1–10 kDa and >10 kDa) and hydrophobicity (hydrophilic, transphilic and hydrophobic) were prepared and coagulated with Al0, Al13 and Al30. The molecular-level characteristics of DOM molecules that were removed or resistant to removal by Al species were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed that at the molecular level, saturated and reduced tannins and lignin-like compounds containing abundant carboxyl groups exhibited higher coagulation efficiency. Unsaturated and oxidized lipids, protein-like, and carbohydrates compounds were relatively resistant to Al coagulation due to their higher polarity and lower content of carboxyl groups. Al13 removed molecules across a wider range of molecular weights than Al0 and Al30, thus the DOC removal efficiency of Al13 was the highest. This study furthers the understanding of interactions between Al species and DOM, and provides scientific insights on the operation of water treatment plants to improve control of DOM.

The glass transition temperature of isolated native, residual, and technical lignin

Abstract The glass transition temperatures (T g) of native, residual, and technical lignins are important to lignocellulose pulping, pulp processing and side stream utilization; however, how the structural changes from native to residual and technical lignin influences T g has proven difficult to elucidate. Since the T g of macromolecules is greatly influenced by the molecular weight, low-molecular-weight fractions, such as milled wood lignin (MWL), are poor representatives of lignin in the cell wall. To circumvent this problem, lignins of both high yield and purity were isolated from Norway spruce and softwood kraft pulp using the enzymatic mild acidolysis lignin (EMAL) protocol. Technical softwood kraft lignin was also fractionated into groups of different molecular weights, to acquire lignin that spanned over a wide molecular-weight range. A powder sample holder for dynamic mechanical analysis (DMA), was used to determine the T g of lignins, for which calorimetric methods were not sensitive enough. The T gs of EMAL were found to be closer to their in situ counterparts than MWL.

Enhanced TROSY Effect in [2‐19F, 2‐13C] Adenosine and ATP Analogs Facilitates NMR Spectroscopy of Very Large Biological RNAs in Solution

AbstractLarge RNAs are central to cellular functions, but characterizing such RNAs remains challenging by solution NMR. We present two labeling technologies based on [2‐19F, 2‐13C]‐adenosine, which allow the incorporation of aromatic 19F‐13C spin pairs. The labels when coupled with the transverse relaxation optimized spectroscopy (TROSY) enable us to probe RNAs comprising up to 124 nucleotides. With our new [2‐19F, 2‐13C]‐adenosine‐phosphoramidite, all resonances of the human hepatitis B virus epsilon RNA could be readily assigned. With [2‐19F, 2‐13C]‐adenosine triphosphate, the 124 nt pre‐miR‐17‐NPSL1‐RNA was produced via in vitro transcription and the TROSY spectrum of this 40 kDa [2‐19F, 2‐13C]‐A‐labeled RNA featured sharper resonances than the [2‐1H, 2‐13C]‐A sample. The mutual cancelation of the chemical‐shift‐anisotropy and the dipole‐dipole‐components of TROSY‐resonances leads to narrow linewidths over a wide range of molecular weights. With the synthesis of a non‐hydrolysable [2‐19F, 2‐13C]‐adenosine‐triphosphate, we facilitate the probing of co‐factor binding in kinase complexes and NMR‐based inhibitor binding studies in such systems. Our labels allow a straightforward assignment for larger RNAs via a divide‐and‐conquer/mutational approach. The new [2‐19F, 2‐13C]‐adenosine precursors are a valuable addition to the RNA NMR toolbox and will allow the study of large RNAs/RNA protein complexes in vitro and in cells.

Enhanced TROSY Effect in [2-19 F, 2-13 C] Adenosine and ATP Analogs Facilitates NMR Spectroscopy of Very Large Biological RNAs in Solution.

Large RNAs are central to cellular functions, but characterizing such RNAs remains challenging by solution NMR. We present two labeling technologies based on [2-19 F, 2-13 C]-adenosine, which allow the incorporation of aromatic 19 F-13 C spin pairs. The labels when coupled with the transverse relaxation optimized spectroscopy (TROSY) enable us to probe RNAs comprising up to 124 nucleotides. With our new [2-19 F, 2-13 C]-adenosine-phosphoramidite, all resonances of the human hepatitis B virus epsilon RNA could be readily assigned. With [2-19 F, 2-13 C]-adenosine triphosphate, the 124 nt pre-miR-17-NPSL1-RNA was produced via in vitro transcription and the TROSY spectrum of this 40 kDa [2-19 F, 2-13 C]-A-labeled RNA featured sharper resonances than the [2-1 H, 2-13 C]-A sample. The mutual cancelation of the chemical-shift-anisotropy and the dipole-dipole-components of TROSY-resonances leads to narrow linewidths over a wide range of molecular weights. With the synthesis of a non-hydrolysable [2-19 F, 2-13 C]-adenosine-triphosphate, we facilitate the probing of co-factor binding in kinase complexes and NMR-based inhibitor binding studies in such systems. Our labels allow a straightforward assignment for larger RNAs via a divide-and-conquer/mutational approach. The new [2-19 F, 2-13 C]-adenosine precursors are a valuable addition to the RNA NMR toolbox and will allow the study of large RNAs/RNA protein complexes in vitro and in cells.

Change in chemical composition and enhancement of intestinal microflora of acid hydrolyzed polysaccharides from Zizyphus jujube and Sterculia lychnophora

The homology between food and medicine has been a successful and well-accepted concept in traditional medicine, where people believe that beneficial naturally available substances can be replenished via diet to promote health. In this study, the polysaccharides in jujube fruit (Ziziphus jujuba Mill.) and dried boat-fruited Sterculia seeds (Sterculia lychnophora) were extracted using different methods (water, acid, and alkaline extraction), and their physicochemical properties and compositions were investigated. Additionally, the effects of polysaccharides on the growth of known intestinal bacteria were investigated using in vitro incubation. The results showed that the acid and alkaline extraction methods resulted in the highest yields of polysaccharides with a high uronic acid content and satisfactory antioxidant activity. The water-extracted polysaccharides exhibited a suitable viscosity. Moreover, the water-extracted polysaccharides were acid-hydrolyzed for 2–6 h, followed by gel permeation chromatography (GPC) to obtain acidic hydrolyzed polysaccharides with a wide range of molecular weights and high carbohydrate contents. Subsequently, five known strains of intestinal bacteria cultured with the acidic hydrolyzed polysaccharides from jujube fruits and pandahai (10 mg/mL) were found to proliferate in Bifidobacterium bifidum, Bifidobacterium longum, Lactobacillus delbrueckii, and Propionibacterium freudenreichir in 0–48 h cultures. However, further evidence is required to validate these results, either in gastrointestinal simulations or animal models.

Quantitation of polyethylene glycol by size exclusion chromatography with charged aerosol, differential refractive index, and multi-angle light scattering detectors

Polyethylene glycol (PEG) has found tremendous applications in pharmaceutical products and has played a critical role in PEGylated drug modalities to improve pharmacokinetic properties and biological efficacy. The characterization and quantitation of PEGs are essential to control manufacture process and drug product quality. However, the assay value of PEG could change dramatically depending on the structures of the PEG and the detection techniques used. In this study, we developed a size exclusion chromatographic (SEC) method for quantitative PEG analysis, and we systematically evaluated the performance of three online detectors with different operating principles: a charged aerosol detector (CAD), a differential refractive index (dRI) detector, and a multi-angle light scattering detector (MALS). Fourteen PEG compounds covering a wide range of molecular weight (MW, 1 – 40 kDa) and molecular architectures (linear, branched, Y-shaped and multi-arm geometries) were evaluated by these three detection techniques. Our study revealed that the dRI showed the most universal responses among all the PEGs regardless of their molecular weight or geometries. In the contrast, CAD and MALS detector showed MW-dependent and semi-universal geometry-dependent responses. Another key finding is that the relative response factor for each multi-arm PEG in the CAD and the MALS were inversely correlated, suggesting both can be applied to qualitatively assess polymers of different architectures, including the ones with subtle differences in their core structures. The comparison of the three detectors not only provides the fundamental and comprehensive understanding of PEG quantitation but also enables the process development and control of high-quality PEGs in producing PEGylated therapeutics in the pharmaceutical industry.

Intrinsic viscosity and dielectric relaxation of ring polymers in dilute solutions.

The absence of chain ends makes ring polymers distinctly different from their linear analogues. The intrinsic viscosity, complex viscosity and the dielectric relaxation of ring polymers are investigated within the tenets of the optimized Rouse-Zimm theory. The distance dependent excluded volume interactions (EVIs) are obtained from Flory's mean field theory. The hydrodynamic interactions (HIs) between the pairs of monomers are estimated using the preaveraged Oseen tensor. The intrinsic viscosity of linear and ring polymers both with and without EVI are compared as a function of ring size. A monotonically increasing trend of the intrinsic viscosity is observed in both cases. The intrinsic viscosity of both linear and ring polymers both with and without EVI show a very good agreement with the experimental results of polystyrene over a wide range of molecular weights in both good and theta solvents, respectively. The fractal dimensions of the ring polymers with EVI lie between that of a random walk and a self-avoiding walk model of linear polymers in three dimensions. The ring size increases with EVI and the effect of EVI is stronger on larger rings than that on smaller rings. The dielectric relaxation follow a connectivity independent universal scaling behavior at low and high frequency regions. The imaginary part of the complex dielectric susceptibility displays a local maxima in the intermediate frequency region, which reveals a structure dependent behavior of the rings. The theoretically calculated dielectric loss of ring polymers with HI matches well with those obtained from experiments.

EPURISp: Combining Enzymatic Digestion, Ultrafiltration, and Rapid In Situ Sample Purification for High-performance Proteomics.

High-performance liquid tandem mass spectrometry (HPLC-MS) is widely employed for protein analysis in biological systems. However, conventional proteomic sample pretreatment methods suffer from multiple steps and poor reproducibility. In this study, we introduce EPURISp (Enzymatic Digestion with Ultrafiltration and Rapid In-situ Sample Purification), a novel proteomic pretreatment technique that combines enzymatic digestion, ultrafiltration, and one-step temperature-controlled vacuum drying for efficient desalting. The EPURISp method exhibits excellent protein recovery rates across a wide range of molecular weights and hydrophilicity, surpassing traditional C18 desalting approaches. Practical proteomic analysis (PXD044209) utilizing EPURISp demonstrates the highest protein identification yield with remarkable reproducibility, which is particularly advantageous in membrane protein identification. Notably, EPURISp exhibits superior performance in minimizing oxidation and deamidation modifications compared with conventional FASP methods. This innovative EPURISp method represents a significant advancement in proteomics analysis, providing reliable and efficient results for mass spectrometry.

Superhydrophobic Nanoparticles: An Efficiently Selective Adsorbent for Surfactant-Like Contaminants from Complex Wastewater Matrices.

Surfactant-like contaminants (SLCs) with distinctive amphiphilic structures have become a global concern in wastewater due to their toxicity and persistency. Despite extensive efforts, achieving efficient and selective SLCs removal remains challenging because of their wide range of molecular weights and complex functional group compositions. Superhydrophobic nanoparticles can potentially tackle this challenge by targeting the long oleophilic chains of SLCs. However, conventional contact angle measurements hinder hydrophobicity characterization and corresponding selectivity research because of the powder morphology of nanoparticles. Herein, the authors offered information regarding the distribution of water molecular probes in surfaces and proposed a quantitative characterization approach based on low-field nuclear magnetic resonance. Through synthesizing superhydrophobic and hydrophilic polydopamine nanospheres with similar morphologies, the selective adsorption potential of superhydrophobic nanoparticles for SLCs is systematically demonstrated. As revealed by the interaction mechanisms, the superhydrophobic surface of nanospheres increased its affinity and selectivity for SLCs adsorption by enhancing hydrophobic interactions. Superhydrophobic modification achieved ten times the adsorption capacity of sodium dodecyl benzene sulfonate, an exemplified surfactant, compared with pristine nanoparticles. By regulated self-polymerization, the superhydrophobic nanospheres are coated onto the surface of a 3D sponge and enable efficient selective SLCs adsorption from highly polluted leachate matrices with long-term stability and reusability.

An H2 O-Initiated Crosslinking Strategy for Ultrafine-Nanoclusters-Reinforced High-Toughness Polymer-In-Plasticizer Solid Electrolyte.

Incorporating plasticizers is an effective way to facilitate conduction of ions in solid polymer electrolytes (SPEs). However, this conductivity enhancement often comes at the cost of reduced mechanical properties, which can make the electrolyte membrane more difficult to process and increase safety hazards. Here, a novel crosslinking strategy, wherein metal-alkoxy-terminated polymers can be crosslinked by precisely controlling the content of H2 O as an initiator, is proposed. As a proof-of-concept, trimethylaluminum (TMA)-functionalized poly(ethylene oxide) (PEO) is used to demonstrate that ultrafine Al-O nanoclusters can serve as nodes to crosslink PEO chains with a wide range of molecular weights from 10000 to 8000000gmol-1 . The crosslinked polymer network can incorporate a high concentration of plasticizers, with a total weight percentage over 75%, while still maintaining excellent stretchability (4640%) and toughness (3.87×104 kJm-3 ). The resulting electrolyte demonstrates high ionic conductivity (1.41mScm-1 ), low interfacial resistance toward Li metal (48.1Ωcm2 ), and a wide electrochemical window (>4.8V vs Li+ /Li) at 30°C. Furthermore, the LiFePO4 /Li battery shows stable cycle performance with a capacity retention of 98.6% (146.3mAhg-1 ) over 1000 cycles at 1C (1C=170mAhg-1 ) at 30°C.

A strategy to tailor the mechanical and degradation properties of PCL-PEG-PCL based copolymers for biomedical application

Biodegradable and biocompatible 3D printable biomaterials with tunable mechanical properties and degradation rate adapted to target tissues were urgently required to manufacture scaffolds for tissue regeneration. Herein, a strategy based on a series of copolymers are proposed where the mechanical and degradation properties can be optimized regarding the specific biological application. With this purpose, poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone) (PCL-PEG-PCL, PCEC) triblock co-polymers with high molecular weight were synthesized by using PEG with a wide range of molecular weight (from 0.6 kg/mol to 35 kg/mol) as macroinitiators. PCEC copolymers exhibited tunable mechanical properties with an elastic modulus in the range 338–705 MPa and a degradation rate from 60% mass loss after 8 h to 70% mass loss after 23 days in accelerated tests, as well as excellent cytocompatibility and cell attachment after culture with mouse fibroblast L929 cells. The mechanisms responsible for these properties were ascertained by means of different techniques to ascertain the structure–property relationship in PCEC copolymers. Furthermore, it was shown that it is possible to manufacture PCEC scaffolds by 3D printing with excellent dimensional accuracy and controlled microporosity. This study provides a promising strategy to design, select, and fabricate copolymers with tunable mechanical properties and degradation rate for tissue engineering applications.

A Graphene-Coated Silicon Wafer Plate Improves the Sensitivity and Reproducibility of MALDI-TOF MS Analysis of Proteins.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used to analyze small and large molecules. However, proteins are difficult to analyze with MALDI-TOF MS in clinical applications because of their low ionization efficiency and heterogeneous crystallization with the matrix on the sample spots. Here, we investigate the potential of a customized graphene-coated silicon wafer (G/SiO2) plate for MALDI-TOF MS analysis of a clinically important protein, KPC-2, in comparison with a conventional stainless steel (SUS) plate. Our results demonstrate that the G/SiO2 plate outperforms the SUS plate in terms of sensitivity, reproducibility, and mass accuracy/precision across a wide range of molecular weights, even with highly complex samples. Furthermore, a five-day robustness test confirms the practical applicability of the G/SiO2 plate for the reliable identification of target protein(s) in MALDI-TOF MS analysis. Overall, our findings suggest that the use of the G/SiO2 plate holds great potential for improving the sensitivity and reproducibility of MALDI-TOF MS analysis for the identification of proteins, making it a promising tool for clinical applications.

μPESI-MS/MS System for Screening and Quantitating Drugs in Plasma Samples.

Recently, we developed a novel microprobe electrospray ionization (μPESI) source and its coupled MS (μPESI-MS/MS) system. Here, we aimed to widely validate the μPESI-MS/MS method for quantitative analysis of drugs in plasma samples. Furthermore, the relationship between the quantitative performance of the μPESI-MS/MS method and the physicochemical properties of target drugs was analyzed. The μPESI-MS/MS methods for quantitative analysis of 5 representative drugs with a relatively wide range of molecular weight, pKa, and log P values were developed and validated. The results showed that the linearity, accuracy, and precision of these methods met the requirements of the European Medicines Agency (EMA) guidance. Then a total of 75 drugs from plasma samples were primarily detected using the μPESI-MS/MS methods, among which 48 drugs could be quantitatively measured. Logistics regression suggested that drugs with significantly greater log P and physiological charge had better quantitative performance using the μPESI-MS/MS method. Collectively, these results clearly demonstrate the practical application of the μPESI-MS/MS system as a rapid approach to the quantitative analysis of drugs in plasma samples.

Properties of Polysulphones Synthetized for Forming of Porous Hollow-Fiber Membranes

For the first time, for the problem of hollow fiber membranes spinning, polysulfones in a wide range of molecular weights (42 000–184 000 g/mol) were synthesized in such aprotic dipolar solvents as dimethylacetamide, N-methyl-2-pyrollidone, and dimethyl sulfoxide. The dependence of the thermal and mechanical properties of polysulfones on molecular weight characteristics has been studied. A comparison of the mechanical properties of the synthesized PSF, commercial PSF Ultrason S 6010 (BASF, Germany) and PSF-150 (JSC Institute of Plastics, Russia) showed that the synthesized polymers are not inferior to commercial analogues. Some synthesized polymers surpass commercial PSF in terms of elasticity and strength modulus. Based on the study of the spinning solutions dynamic viscosity, promising PSF samples were selected for the formation of porous hollow fiber supports. It was found that hollow-fiber porous support from a PSF sample with a molecular weight of 110 000 g/mol have a high nitrogen permeability of 47.5 m3/m2 · h · bar. Such supports are promising for casting highly permeable composite membranes with a thin selective layer.

Iron ethylene polymerization catalysts incorporating trifluoromethoxy functionality: Effects on PE molecular weight and productivity

The capacity to broaden the range of molecular weights displayed by polyolefinic materials is an important factor to be considered in the design of polymerization catalysts. Herein, the 2,6-dibenzhydryl-4-trifluoromethoxy modified bis(imino)pyridyl-ferrous chlorides, [2-[CMeN{2,6-{(C6H5)2CH}2-4-(F3CO)C6H2}]-6-(CMeNAr)C5H3N]FeCl2 [Ar = 2,6-Me2C6H3Fe1, 2,6-Et2C6H3Fe2, 2,6-i-Pr2C6H3Fe3, 2,4,6-Me3C6H2Fe4, 2,6-Et2-4-MeC6H2Fe5], are used as precatalysts in the solution polymerization of ethylene. On the activation with either MAO or MMAO, all complexes displayed high productivity [up to 18.4 × 106 g (PE) mol-1 (Fe) h-1 for Fe5/MAO], generating highly linear polyethylenes with a wide range of molecular weights (Mw range: 0.85 × 103 to 8.80 × 105 g mol-1). Notably, higher activity was achieved in hexane than in toluene under MAO activation, while the opposite trend was seen with MMAO, highlighting the key role played by solvent in the polymerization process. By comparison with structurally related iron catalysts, the presence of the electron withdrawing para-trifluoromethoxy group has the effect of increasing the molecular weight of the polyethylene. In addition to the polymerization studies, full synthetic and characterization details are presented for Fe1-Fe5 including the X-ray structures of Fe1 and Fe2.

Hyaluronic Acid as Bioink and Hydrogel Scaffolds for Tissue Engineering Applications.

Bioprinting is an additive manufacturing technique that focuses on developing living tissue constructs using bioinks. Bioink is crucial in determining the stability of printed patterns, which remains a major challenge in bioprinting. Thus, the choices of bioink composition, modifications, and cross-linking methods are being continuously researched to augment the clinical translation of bioprinted constructs. Hyaluronic acid (HA) is a naturally occurring polysaccharide with the repeating unit of N-acetyl-glucosamine and d-glucuronic acid disaccharides. It is present in the extracellular matrix (ECM) of tissues (skin, cartilage, nerve, muscle, etc.) with a wide range of molecular weights. Due to the nature of its chemical structure, HA could be easily subjected to chemical modifications and cross-linking that would enable better printability and stability. These interesting properties have made HA an ideal choice of bioinks for developing tissue constructs for regenerative medicine applications. In this Review, the physicochemical properties, reaction chemistry involved in various cross-linking strategies, and biomedical applications of HA have been elaborately discussed. Further, the features of HA bioinks, emerging strategies in HA bioink preparations, and their applications in 3D bioprinting have been highlighted. Finally, the current challenges and future perspectives in the clinical translation of HA-based bioinks are outlined.

On-line reversed-phase liquid chromatography x supercritical fluid chromatography coupled to high-resolution mass spectrometry: A powerful tool for the characterization of advanced biofuels

Bio-oils obtained by thermochemical or biochemical conversion of biomass represent a promising source of energy to complement fossil fuels, in particular for maritime or air transport for which the use of hydrogen or electricity appears complicated. As these bio-oils are very rich in water and heteroatoms, additional treatments are necessary before they can be used as biofuel. In order to improve the efficiency of these treatments, it is important to have a thorough knowledge of the composition of the bio-oil. The characterization of bio-oils is difficult because they are very complex mixtures with thousands of compounds covering a very wide range of molecular weight and polarity. Due to the high degree of orthogonality between the two chromatographic dimensions, the on-line combination of reversed-phase liquid chromatography and supercritical fluid chromatography (on-line RPLC x SFC) can significantly improve the characterization of such complex matrices. The hyphenation was optimized by selecting, in SFC, the stationary phase, the co-solvent, the make-up solvent prior to high resolution mass spectrometry (HRMS) and the injection solvent. Additionally, a new interface configuration is described. Quality descriptors such as the occupation of the separation space, the peak shapes and the signal intensity were considered to determine the optimal conditions. The best results were obtained with bare silica, a co-solvent composed of acetonitrile and methanol (50/50, v/v), a make-up solvent composed of methanol (90%) and water (10%) with formic acid (0.1%), an addition of co-solvent through an additional pump for SFC separation in a 2.1 mm column, and an hydro-organic solvent as injection solvent. The optimized setup was used to analyze two microalgae bio-oils: the full bio-oil coming from hydrothermal liquefaction and Soxhlet extraction of microalgae, and the gasoline cut obtained after distillation of the full bio-oil. Results in on-line RPLC x SFC-qTOF were particularly interesting, with very good peak shapes and high reproducibility. Moreover, the high degree of orthogonality for microalgae bio-oils of RPLC and SFC was highlighted by the very large occupation of the separation space. Isomeric profiles of compound families could be obtained in RPLC x SFC-qTOF and many isomers not separated in SFC alone were separated in RPLC and vice versa, thus showing the complementarity of the two chromatographic techniques.