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Beech sawdust was treated with a ternary solvent system based on binary aqueous ethanol with partial substitution of ethanol by acetone at four different water contents (60, 50, 40, and 30%v/v). In addition to standard, i.e., noncatalyzed treatments, the application of inorganic acid in the form of 20 mm H2SO4 was evaluated. The various solvent systems were applied at 180 °C for 60 min. The obtained biomass fractions were characterized by standard biomass compositional methods, i.e., sugar monomer and oligomer contents, dehydration product contents of the aqueous product, and lignin, cellulose, and hemicellulose contents in isolated solid fractions. More advanced analyses were performed on the lignin fractions, including quantitative 13C NMR analyses, 1H-13C HSQC analysis, size exclusion chromatography, and pyrolysis-GC/MS, and the aqueous product, in the form of size exclusion chromatography and determination of total phenol contents. The picture emerging from the thorough analytical investigation performed on the lignin fractions is consistent with that resulting from the characterization of the other fractions: results point toward greater deconstruction of the lignocellulosic recalcitrance upon higher organic solvent content, replacing ethanol with acetone during the extraction, and upon addition of mineral acid. A pulp with cellulose content of 94.23 wt % and 95% delignification was obtained for the treatment employing a 55/30/15 EtOH/water/acetone mixture alongside 20 mm H2SO4. Furthermore, the results indicate the formation of two types of organosolv furan families during treatment, which differ in the substitution of their C1 and C5. While the traditional lignin aryl-ether linkages present themselves as indicators for process severity for the nonacid catalyzed systems, the distribution of these furan types can be applied as a severity indicator upon employment of H2SO4, including their presence in the isolated lignin fractions.

The ever faster changing socioeconomic and environmental conditions require more than ever a proper valorisation of renewable biomass. Lignin, as one of the main components of land-based renewable biomass, is receiving ever more attention also as starting material for the production of monomeric value-added aromatic molecules, and/or fuels. While lignin depolymerisation, or degradation, can be done in form of a ‘black-box’ approach, a more reasonable and desirable fashion would be a structure-based approach. The presented overview presents the research field ‘lignin degradation’ starting from a short introduction regarding lignin and its structural understanding, to then enter the traditional area of wet-chemical lignin degradation. Discussion is then expanded to catalytic conversion processes and biotechnological depolymerisation approaches. The chapter will finish with a hint on thermal and electrochemical methods for lignin degradation.

Curing cancer presents a series of difficulties, with the pressing one being concerned with targeting selectively cancer cells. Equally important are aspects of the diagnosis and the monitoring of treatment efficacy. [1] This study aims at optimizing an innovative combined drug delivery and diagnosis system, i.e., a theragnosis approach, which is based on drug-loaded multifunctional tannin-based microcapsules (TMCs).[2] The envisaged system exploits the overexpressed folate receptors naturally present on cancer cells[3] for a targeted delivery mechanism via folate moieties that are linked via PEG chains to the capsule surfaces. Simple PEG moieties are surrounding these receptors in form of a stealth system lowering premature metabolic digestions. With the additional encapsulation of an anticancer drug like 5-Fluorouracil, a concomitant controlled release of an active principle at the cancer site is achieved. Diagnosis-relevance is brought into the system in form of MRI-active metal cations such as Gadolinium(III) incorporated into the shell, exploiting the metal-complexing characteristics of the shell material. The TMCs are generated by ultrasonicating a biphasic system comprising an aqueous solution of tannin or functionalized tannin, providing the eventually functionalized shell material as well as the Gd(III) salt, and an olive oil phase that functions as core material while being suitable to host the active. Resulting tannin microcapsules are characterised by means of optical and transmission electron microscopy. TMCs sizes have been determined using DLS analyses while zeta potential measurements revealed structural arrangements on the surfaces. Encapsulation efficiency and release studies were conducted for monitoring active release. Biological tests performed so far using standard capsule systems and the stained variants do not indicate any toxicity against the zebrafish embryos.

This study, in collaboration with the Arvedi Laboratory of Non-Invasive Diagnostics (University of Pavia) at the Museo del Violino of Cremona, aimed at developing a new hydrogel system for the cleaning of historical wooden surfaces, with a particular focus on string musical instruments. The cleaning of historical wooden instrument is traditionally performed using free water-based solvent, which are able to remove pollutants like dirt, soil and human sweat. However, due to the hydrophilic character of wooden surfaces, the loading of water should be localized in specific areas, avoiding excessive solvent leaching and the consequent damage risks. Konjac glucomannan (KGM), a biopolymer of natural origin, was chosen for our study because of its ability to absorb and retain significant amounts of water through its high content of hydroxyl groups. Hydrogel formulation as proposed in previous studies [1], consisting of KGM crosslinked with borax (sodium tetraborate decahydrate), was optimized, and an improved crosslinking method involving boric acid and sodium hydroxide (NaOH) was introduced, resulting in uniformly crosslinked gels with enhanced moisture retention and elasticity. KGM polymer matrix was also subsequently modified with natural polyphenols (PPs), in order to provide an alternative sustainable crosslinking option alongside the introduction of antioxidant properties and protection against UV radiation [2]. Three PPs have been selected to implement the modification: softwood kraft lignin (SKL), Vitis Vinifera tannin (Vv) and tannic acid (TA). PPs have additionally been functionalized with epichlorohydrin (ECH) to allow for a covalent bonding between the PP and KGM and to induce self-polymerization of the PP for reducing leaching especially of smaller PPs from the gel to the treated surface. Various analytical techniques were employed to characterize the starting PPs and their derivatives, and to analyze the morphology and moisture properties of the hydrogels comp

The biotechnological conversion of lignocellulosic biomass is an interesting option within the development and refinement of biorefinery processes. While the use of enzymes for cellulose conversion is essentially matured, enzymatic (downstream) valorisation of lignins using enzymatic processes continues to pose challenges. When thinking of lignocellulosic enzymes for such processes, the mentioned challenges derive from a lack of control of polymerisation/re-polymerisation, loss of enzymatic activity due to adverse environments generated by the compromise between enzyme needs and lignin solubility, enzyme inhibition, etc. Some of these challenges can eventually be circumvented rethinking the set-up for doing enzymatic lignin transformations. One aspect of such a rethinking could involve the use of more dynamic reaction settings, avoiding long contact times between enzyme and the products they have formed. This can be eventually facilitated going for flow chemistry principles, applied to the enzymatic lignin transformation. We present here results obtained for the use of some commercially available laccases (EC 1.10.3.2), treated in various modes to be used in a flow chemical setting for downstream lignin valorisations, including degradation and functionalisation. The presentation will highlight the challenges encountered and connected with enzyme manipulation and the incorporation of immobilised enzymes in experimental flow reactors. Scope and limitations of this approach are presented using targeted example transformation, and obtained results will also be discussed in light of process- and set-up-dependent kinetic aspects.

Organosolv lignins (OSLs) are important byproducts of the cellulose-centred biorefinery that need to be converted in high value-added products for economic viability. Yet, OSLs occasionally display characteristics that are unexpected looking at the lignin motifs present. Applying advanced NMR, GPC, and thermal analyses, isolated spruce lignins were analysed to correlate organosolv process severity to the structural details for delineating potential valorisations. Very mild conditions were found to not fractionate the biomass, causing a mix of sugars, lignin-carbohydrate complexes (LCCs), and corresponding dehydration/degradation products and including pseudo-lignins. Employing only slightly harsher conditions promote fractionation, but also formation of sugar degradation structures that covalently incorporate into the oligomeric and polymeric lignin structures, causing the isolated organosolv lignins to contain lignin-humin hybrid (HLH) structures not yet evidenced as such in organosolv lignins. These structures effortlessly explain observed unexpected solubility issues and unusual thermal responses, and their presence might have to be acknowledged in downstream lignin valorisation.

The moisture resistance of friction-welded wood joints can be improved by applying bio-based bonding additives. Several biomolecules including tannic acid, organosolv lignin from hardwood, kraft lignin from softwood, and derivates thereof, were investigated regarding their applicability as bonding additives in the friction welding process. Welding with kraft lignin showed significantly increased moisture stability after 24 h water immersion. An average wet bond strength of 1.5 MPa compared to 0.38 MPa of untreated spruce was obtained. Modification of kraft lignin through succinylation, acetylation or depolymerisation led to no further improvement in moisture stability. Depolymerised kraft lignin resulted in an even higher delamination rate of the samples during water immersion than untreated samples. Structural analysis of the lignin variations by FTIR-ATR, GPC and 31P NMR in combination with thermal analysis by TGA and DSC showed the impact of various structural and chemical features on the thermal behaviour and intermolecular interactions of the applied lignin.

Advancements in fluidized bed pyrolysis mechanisms and analytical methodologies are critical for progress in the biorefinery sector in general and the aviation fuel sector in particular. The statistical modelling of pyrolysis product yields and composition allowed us to observe advantages of operating temperature and feedstock selections over the torrefaction process and catalyst addition in a fluidized bed reactor. Results suggest that the chemical composition and physical properties of bio-oil from pyrolysis of olive stones at 600°C and pinewood pellets at 500°C are the most suitable for use as fuels. This work suggests that only combined use of selected gas chromatography mass spectroscopy, UV fluorescence, nuclear magnetic resonance spectroscopy, and rheology can provide comprehensive information on pyrolysis bio-oil composition. Importantly from a technological point of view, bio-oil was characterized i) by a viscosity similar to that of fossil-based oil; ii) by a low oxygen and water content; and iii) by a balanced composition of aliphatic and aromatic species. These factors indicate that bio-oil from fluidized bed pyrolysis of biomasses is a promising material for use in the aviation industry and energy production.

Salicylate and benzoate sunscreen agents have been encapsulated by the green, fast and robust ultrasound technique in tannin microcapsules (TMCs). The generated TMCs, obtained without use of cross linking agents, were fully characterised, including encapsulation efficiencies with respect to the encapsulated actives. Release kinetics of TMCs have been studied mimicking skin conditions. Body cream base samples containing specific concentrations of microcapsules filled with sunscreen actives were prepared and showed synergistic effects in terms of UV-protection abilities generated by the interplay between sunscreen actives and natural tannin polyphenols. The synergistic effect exerted by the tannin and the controlled active release allows to reduce the amount of synthetic sunscreens needed, and does thus contribute to the development of more sustainable and environmentally benign UV-protection systems.

Background: Tannins have demonstrated antibacterial and antibiofilm activity, but there are still unknown aspects on how the chemical properties of tannins affect their biological properties. We are interested in understanding how to modulate the antibiofilm activity of tannins and in delineating the relationship between chemical determinants and antibiofilm activity. Materials and methods: The effect of five different naturally acquired tannins and their chemical derivatives on biofilm formation and planktonic growth of Salmonella Typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was determined in the Calgary biofilm device. Results: Most of the unmodified tannins exhibited specific antibiofilm activity against the assayed bacteria. The chemical modifications were found to alter the antibiofilm activity level and spectrum of the tannins. A positive charge introduced by derivatization with higher amounts of ammonium groups shifted the anti-biofilm spectrum toward Gram-negative bacteria, and derivatization with lower amounts of ammonium groups and acidifying derivatization shifted the spectrum toward Gram-positive bacteria. Furthermore, the quantity of phenolic OH-groups per molecule was found to have a weak impact on the anti-biofilm activity of the tannins. Conclusion: We were able to modulate the antibiofilm activity of several tannins by specific chemical modifications, providing a first approach for fine tuning of their activity and antibacterial spectrum.

Lignocellulosic biomass is one of the most important renewable materials to replace carbon-based fossil resources. Solvent-based fractionation is a promising route for fractionation of biomass into its major components. Processing is governed by the employed solvent-systems properties. This review sheds light on the factors governing both dissolution and potential reactivities of the chemical structures present in lignocellulose, highlighting how proper understanding of the underlying mechanisms and interactions between solute and solvent help to choose proper systems for specific fractionation needs. Structural and chemical differences between the carbohydrate-based structural polymers and lignin require very different solvents capabilities in terms of causing and eventually stabilizing conformational changes and consequent activation of bonds to be cleaved by other active components in the. A consideration of potential depolymerization events during dissolution and energetic aspects of the dissolution process considering the contribution of polymer functionalities allow for a mapping of solvent suitability for biomass fractionation.

Conversion of organosolv lignins isolated with and without an inorganic acid catalyst (H2SO4) from hard- and softwood (birch and spruce) into bio-oil through hydrothermal liquefaction has been investigated. Furthermore, fractions of the isolated bio-oils were catalytically deoxygenated to improve the bio-oil properties. As elucidated through NMR, both biomass source and extraction mode influence the bio-oil product distribution. Depending on whether the lignins carry a high content of native structures, or are depolymerized and subsequently condensed in the presence of sugar dehydration products, will dictate heavy oil (HO) and light oil (LO) distribution, and skew the HO product composition, which again will influence the requirements upon catalytical deoxygenation.