Javier Calvo

Polyether polyurethane foams are widely used materials in everyday life, yet they are highly recalcitrant and difficult to recycle. Until now, no efficient bioprocess currently exists for their depolymerization. Lastly, the use of enzymes has revolutionized plastic recycling, but their application to polyurethanes remains in its infancy. In this work, we selected some enzymes capable of cleaving urethane bonds through alcoholysis, a mechanism that goes beyond conventional enzymatic hydrolysis. Among them, two lipases from Thermomyces lanuginosus and Rhizopus oryzae proved particularly promising when using methanol and ethanol as reaction agents. These enzymes successfully degraded polyether polyurethane foams, releasing polyols and alkyl carbamates. The recovered polyols could be isolated and subsequently reused in a new polymerization process, generating partially recycled foams. This enzymatic solvolysis approach in alcohol media was extended to non-isocyanate polyurethane foams, opening new paths for depolymerizing and recycling complex plastics, thereby contributing to a more circular plastic economy.

Los tumores periampulares son raros y a menudo silenciosos, incluso en etapas avanzadas. Se presenta un caso de una mujer de 88 años con dilatación coledocal de 39 mm, neoplasia periampular y metástasis hepática, quien rechazó cirugía adicional y fue tratada paliativamente.

The acrylation degree of vegetable oils plays a relevant role in determining the mechanical properties of the resulting polymers. Both epoxide and acrylate functionalities participate in polymerization reactions, producing various types of chemical bonds in the polymer network, which contribute to specific properties such as molecular size distribution, crosslinking degree, and glass transition temperature (Tg). The accurate identification of epoxide and acrylated groups in triglyceride molecules helps to predict their behavior during the polymerization process. A methodology based on analytical spectrometric techniques, such as direct infusion, mass spectrometry with electrospray ionization, and ultra-high-performance liquid chromatography, is used in combination with FTIR and ¹H NMR to characterize the epoxy and acrylic functionalities in the fatty chains with different numbers of carbon atoms of partially acrylated triglycerides obtained by a non-catalytic reaction.

Riboflavin-functionalized repeat proteins enable controlling the photocatalytic activation and delivery of Pt anticancer agents in vitro .

Honey, as a nutritious natural sweetener produced by honeybees, offers a unique biochemical composition with great benefit to human health. Transportation and storage conditions as well as violations of processing can lead to decomposition of vitamins, destruction of the integrity of the antioxidant components and enzymes, and further biochemical changes with impact on nutritional quality. We developed a fast detection method of adulterations or changes of honey caused by thermal exposure, which does not require any sample pretreatment. By Fourier-transform infrared spectroscopy, supported by chemometrics methods, we investigated three types of raw honey before and after heat treatment for varying exposure times at different temperatures. Applying principal component analysis and linear discriminant analysis to the preprocessed spectroscopic data, allowed us to discriminate raw honey from thermally altered ones even at low temperatures of 40 °C with high accuracies ≥90%.

Mass spectrometry (MS) is a valuable tool for functional genomic, proteomic, and glycomic studies. In particular, the combination of MS with microarrays is a powerful technique for analyzing the activity of carbohydrate processing enzymes and for the identification of carbohydrate-binding proteins (lectins) in complex matrices. On the other hand, graphene exhibits high desorption/ionization efficiency, good conductivity and optical transparency, specifications of a high-performance component for matrix-assisted laser desorption/ionization (MALDI) platforms. Besides, the chemical functionalization of graphene increases the adsorption capability of functional biomolecules (e.g. receptors), resulting in very stable interfaces. Taking advantage of the properties of graphene, we developed several modified chemical vapor deposited graphene (CVDG)-based glycan arrays on different substrates including ITO and bare glass, as a potential sensing platform for carbohydrate-lectin interactions, which are involved in a plethora of biological processes. The glycan arrays were fully characterized by MALDI-MS analysis and, in some cases, optical microscopy.

This work aims at learning how the size of gold nanocarriers influences the transport of DNA-alkylating antitumoral drugs. For this purpose, we devised conjugates of mercaptoethylmi-tomycin C (MEMC), a DNA alkylating agent, with gold nano-particles of different sizes (2, 5 and 14 nm), and studied how size affects drug cytotoxicity, tumor penetrability, cellular uptake and intracellular localization using two-dimensional (2D) and three-dimensional (3D) cell models. We show that only small, 2 nm nanoparticles can transport MEMC to the cell nucleus, whereas MEMC cell uptake is much lower when delivered by these small nanoparticles than with the larger ones. 3D cellular models showed that smaller nanoparticles can transport MEMC towards deeper areas of tumor spheroids as compared to larger nanoparticles. We discuss the insights of this work towards the efficient delivery of DNA-targeting drugs.

We have recently demonstrated that riboflavin (Rf) functions as unconventional bioorthogonal photocatalyst for the activation of Pt^IV prodrugs. In this study, we show how the combination of light and Rf with two Pt^IV prodrugs is a feasible strategy for light-mediated pancreatic cancer cell death induction. In Capan-1 cells, which have high tolerance against photodynamic therapy, Rf-mediated activation of the cisplatin and carboplatin prodrugs cis,cis,trans-[Pt(NH₃)₂(Cl)₂(O₂CCH₂CH₂CO₂H)₂] (1) and cis,cis,trans-[Pt(NH₃)₂(CBDCA)(O₂CCH₂CH₂CO₂H)₂] (2, where CBDCA = cyclobutane dicarboxylate) resulted in pronounced reduction of the cell viability, including under hypoxia conditions. Such photoactivation mode occurs to a considerable extent intracellularly, as demonstrated for 1 by uptake and cell viability experiments. ¹⁹⁵Pt NMR, DNA binding studies using circular dichroism, mass spectrometry and immunofluorescence microscopy were performed using the Rf-1 catalyst-substrate pair and indicated that cell death is associated with the efficient light-induced formation of cisplatin. Accordingly, Western blot analysis revealed signs of DNA damage and activation of cell death pathways through Rf-mediated photochemical activation. Phosphorylation of H₂AX as indicator for DNA damage, was detected for Rf-1 in a strictly light-dependent fashion while in case of free cisplatin also in the dark. Photochemical induction of nuclear pH₂AX foci by Rf-1 was confirmed in fluorescence microscopy again proving efficient light-induced cisplatin release from the prodrug system.

Nectandra grandiflora Nees (Lauraceae) is a Brazilian native tree recognized by its durable wood and the antioxidant compounds of its leaves. Taking into account that the forest industry offers the opportunity to recover active compounds from its residues and by-products, this study identifies and underlines the potential of natural products from Nectandra grandiflora that can add value to the forest exploitation. This study shows the effect of three different extraction methods: conventional (CE), ultrasound-assisted (UAE) and microwave-assisted (MAE) on Nectandra grandiflora leaf extracts (NGLE) chemical yields, phenolic and flavonoid composition, physical characteristics as well as antioxidant and antifungal properties. Results indicate that CE achieves the highest extraction phytochemical yield (22.16%), but with similar chemical composition to that obtained by UAE and MAE. Moreover, CE also provided a superior thermal stability of NGLE. The phenolic composition of NGLE was confirmed firstly, by colorimetric assays and infrared spectra and then by chromatographic analysis, in which quercetin-3-O-rhamnoside was detected as the major compound (57.75–65.14%). Furthermore, the antioxidant capacity of the NGLE was not altered by the extraction methods, finding a high radical inhibition in all NGLE (>80% at 2 mg/mL). Regarding the antifungal activity, there was observed that NGLE possess effective bioactive compounds, which inhibit the Aspergillus niger growth.