Bioinformatics tools that predict protein stability changes upon point mutations have made a lot of progress in the last decades and have become accurate and fast enough to make computational mutagenesis experiments feasible, even on a proteome scale. Despite these achievements, they still suffer from important issues that must be solved to allow further improving their performances and utilizing them to deepen our insights into protein folding and stability mechanisms. One of these problems is their bias toward the learning datasets which, being dominated by destabilizing mutations, causes predictions to be better for destabilizing than for stabilizing mutations. We thoroughly analyzed the biases in the prediction of folding free energy changes upon point mutations (⁠$ΔΔG0$⁠) and proposed some unbiased solutions. We started by constructing a dataset $Ssym$ of experimentally measured $ΔΔG0$s with an equal number of stabilizing and destabilizing mutations, by collecting mutations for which the structure of both the wild-type and mutant protein is available. On this balanced dataset, we assessed the performances of 15 widely used $ΔΔG0$ predictors. After the astonishing observation that almost all these methods are strongly biased toward destabilizing mutations, especially those that use black-box machine learning, we proposed an elegant way to solve the bias issue by imposing physical symmetries under inverse mutations on the model structure, which we implemented in PoPMuSiC^sym. This new predictor constitutes an efficient trade-off between accuracy and absence of biases. Some final considerations and suggestions for further improvement of the predictors are discussed. Supplementary data are available at Bioinformatics online. The article 10.1093/bioinformatics/bty340/, published alongside this paper, also addresses the problem of biases in protein stability change predictions.

Acrylic photopolymer resins are widely used in stereolithographic 3D printing. However, the growing demand for such thermosetting resins is weighing on global issues such as waste management and fossil fuel consumption. Therefore, there is an increasing demand for reactive components that are biobased and enable recyclability of the resulting thermoset products. In this work, the synthesis of a photo-cross-linkable molecule containing dynamic imine bonds based on biobased vanillin and dimer fatty diamine is described. Using the biobased building blocks, formulations containing reactive diluent and a photoinitiator were prepared. The mixtures could be rapidly cross-linked under UV light, yielding vitrimers. Using digital light processing, 3D-printed parts were prepared, which were rigid, thermally stable, and reprocessed within 5 min at elevated temperature and pressure. The addition of a building block containing a higher concentration of imine bonds accelerated the stress relaxation and improved the mechanical rigidity of the vitrimers. This work will contribute to the development of biobased and recyclable 3D-printed resins to facilitate the transition to a circular economy.

The anthropologic impact on climate has reached a critical level given that society relies on non-renewable fossil resources for energy. Thus, to alleviate this, lignins can play a key role in the transition from petroleum-based chemistry towards a more sustainable and green approach. The commercially available lignins are to a large extent technical lignins, which are obtained from the soda, Kraft or sulfite process, and to a lesser extent, lignins from biorefineries (i.e., organosolv and hydrolysis lignin). However, solely the incorporation of lignins at the application level is insufficient to improve sustainability and increase the greenness of processes. In this case, the path from lignin biomass to the final product should also be considered. Therefore, in this review, initially we present an adaptation of the CHEM21 metrics toolkit to assess the greenness of valorization strategies based on strategically chosen criteria. Subsequently, we present a detailed evaluation of different solvents, demonstrating the greenness of a wide variety of solvents, which will be beneficial to readers. In addition, it can be used as an instrument to design green ionic liquids that can be applied during the valorization of lignins. Furthermore, green lignin modification and depolymerization strategies (to increase the solubility, reactivity and processability and improve the structural uniformity and alter functionalities) are evaluated based on green chemistry principles considering the adapted CHEM21 metrics toolkit. Finally, the methods for processing lignins (i.e., blending and polymer synthesis) are assessed to determine if they can be considered sustainable approaches.

There is an environmental concern regarding the use of petroleum-based lubricants, which are generally toxic and nonbiodegradable. Biobased lubricants, such as vegetable oils, are the alternative: they show excellent lubricity, are readily biodegradable and nontoxic. However, a major disadvantage of using vegetable oils in lubricant applications is their lack of thermo-oxidative stability, which can be improved by antioxidant additives. Here, we propose the use of lignin-based additives in biolubricant formulations to improve this feature, based on lignin’s known antioxidant properties. To ensure a stable dispersion in vegetable oil, lignin was partially esterified. Antioxidant properties of lignin before and after palmitoylation were demonstrated in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Four different lignin-based fractions, commercial Protobind P1000 soda lignin from straw, solvolytically fractionated Protobind P1000 lignin and two lignin fractions from reductively catalyzed fractionation (RCF) of native birch wood, were tested in biolubricant formulations with castor oil as base oil. Those lignin fractions exhibited excellent performance compared to butylated hydroxytoluene (BHT), a commonly used petroleum-based antioxidant. Formulations of modified lignin in castor oil possess improved thermo-oxidative stability, as illustrated by their increased oxidation induction time. Additionally, rheological and tribological tests demonstrate similar, or in some cases improved, lubricating properties compared to castor oil. This study showcases the successful incorporation of lignin-based antioxidants in biolubricant formulations, tackling the major disadvantage of vegetable oils as environment-friendly lubricants.

Biotechnological processes are typically perceived to be greener than chemical processes. A life cycle assessment (LCA) was performed to compare the chemical and biochemical synthesis of lactones obtained by Baeyer–Villiger oxidation. The LCA is prospective (based on experiments at a small scale with primary data) because the process is at an early stage. The results show that the synthesis route has no significant effect on the climate change impact [(1.65±0.59) kg g_product⁻¹ vs. (1.64±0.67) kg g_product⁻¹]. Key process performance metrics affecting the environmental impact were evaluated by performing a sensitivity analysis. Recycling of solvents and enzyme were shown to provide an advantage to the enzymatic synthesis. Additionally, the climate change impact was decreased by 71 % if renewable electricity was used. The study shows that comparative LCAs can be used to usefully support decisions at an early stage of process development.