https://hdl.handle.net/2238/11309 2026-05-12T11:57:16Z https://hdl.handle.net/2238/16337 Spent coffee ground-based materials evaluated by methylene blue removal Araya-Sibaja, Andrea Mariela; Quesada-Soto, Tamara; Vega-Baudrit, José Roberto; Navarro-Hoyos, Mirtha; Valverde-Cerdas, Johnny; Romero-Esquivel, Luis Guillermo Spent coffee grounds (SCG) are produced in large quantities during coffee brewing, contributing to environmental concerns. Additionally, cationic dyes from textile, paper, and leather wastewater pose a major pollution issue. This study explores SCG as an adsorbent for methylene blue (MB) dye. A novel comparison of SCG cleaning methods with warm water, accelerated solvent extraction (ASE), supercritical fluid extraction (SFE), and ultrasound-induced cavitation (US) is presented. In addition, the chemical modifications of SCG using acetylation, acid (HNO3), and base (KOH) treatment that have not been reported before are presented. ATR-FTIR confirmed the inclusion of functional groups, for example, the nitro group in SCG treated with HNO3, and an increase in carboxylic groups in the samples treated with KOH and HNO3. SEM analysis revealed a consistent porous texture across samples, with SCG-SFE, SCG-US, and SCG-HNO3 showing smaller pores, and SCG-ASE displaying elongated cavities. Adsorption isotherm tests followed the Freundlich and Langmuir models, indicating favorable adsorption. The Langmuir maximum adsorption capacity (qmax) varied among cleaning methods from 65.69 mg/g (warm water) to 93.32 mg/g (SFE). In contrast, in base- and acid-treated SCG, a three- to four-fold increase in adsorption capacity was observed, with qmax values of 171.60 mg/g and 270.64 mg/g, respectively. These findings demonstrate that SCG washed with warm water and chemically treated achieves adsorption capacities comparable to other biosorbents reported in the literature. Therefore, SCG represents a promising, low-cost, and sustainable material for removing cationic dyes from wastewater, contributing to waste valorization and environmental protection. Artículo. Instituto Tecnológico de Costa Rica (ITCR). Escuela de Química. Centro de Investigación en Protección Ambiental (CIPA), Laboratorio Nacional de Nanotecnología LANOTEC-CeNAT-CONARE, Universidad Técnica Nacional (UTN), Universidad de Costa Rica (UCR). Departamento de Química. Bioactividad para el Desarrollo Sostenible (BIODESS), Georgetown University. Chemistry Department, 2025 2025-05-20T00:00:00Z https://hdl.handle.net/2238/16335 HRMS characterization and antioxidant evaluation of costa rican spent coffee grounds as a source of bioactive polyphenolic extracts Navarro-Hoyos, Mirtha; Vargas-Huertas, Luis Felipe; Chacón-Vargas, Juan Diego; Leandro-Aguilar, Valeria; Alvarado-Corella, Diego; Vega-Baudrit, Jose Roberto; Romero-Esquivel, Luis Guillermo; Sánchez-Kopper, Andrés; Monge-Navarro, Andrea; Araya-Sibaja, Andrea Mariela Spent coffee grounds constitute a waste product that has attracted potential interest as a rich source of secondary metabolites such as polyphenolic compounds with antioxidant properties. In this work, aqueous extracts from samples of different spent coffee grounds from Costa Rica were prepared and analyzed using ultra-performance liquid chromatography coupled with high-resolution mass spectrometry using a quadrupole time-of-flight analyzer (UPLC-QTOF-ESI MS). This allowed for the identification of twenty-one compounds, includ ing fourteen phenolic acids, three caffeoylquinic lactones, and four atractyligenin diterpenes. In addition, using UPLC coupled with a diode array detector (UPLC-DAD), we quantified the levels of caffeine (0.55–3.42 mg/g dry weight [DW]) and six caffeoylquinic and feruloylquinic acids (0.47–5.34 mg/g DW). The highest value was found for the fine-grind sample (EXP), both for phenolic acids and for total polyphenols (9.59 mg gallic acid equivalents [GAE]/g DW), compared to 2.13 and 1.70 mg GAE/g DW for the medium-grind (GR) and coarse-grind samples (PCR), respectively. The results obtained from the antioxidant evaluations using the 2,2-diphenyl-1-picrylhydrazyl assay (IC50 0.0964–6.005 g DW/L), the ferric-reducing an tioxidant power (PFRAP) analysis (0.0215–0.1385 mmol FeSO4/g DW), the oxygen radical absorbance capacity (ORAC) assessment (45.7–309.7 µmol Trolox/g DW), and the Trolox equivalent antioxidant capacity (TEAC) assay (3.94–23.47 mg Trolox/g DW) also showed the best values for the fine-grind sample, with results similar to or higher than those reported in the literature. Statistical Pearson correlation analysis (p < 0.05) indicated a high correlation (R ≥ 0.842) between all antioxidant analyses, the total polyphenols, and the phenolic acid quantification using UPLC-DAD. These results show the potential for further studies aiming to exploit this waste product’s bioactive properties, constituting the first detailed study of spent coffee grounds from Costa Rica. Artículo. Instituto Tecnológico de Costa Rica (ITCR). Escuela de Química. Centro de Investigación en Protección Ambiental (CIPA), Centro de Investigación y de Servicios Químicos y Microbiológicos (CEQIATEC), Centro Nacional de Alta Tecnologia (CeNAT). Laboratorio Nacional de Nanotecnología, Universidad de Costa Rica (UCR). Departamento de Química, INNOBIOTIQ, Departamento de I+D+i, Georgetown University. Chemistry Department, Universidad Técnica Nacional (UTN), 2025 2025-01-30T00:00:00Z https://hdl.handle.net/2238/9962 Site-specific cleavage of ribosomal RNA in Escherichia coli-based cell-free protein synthesis systems Failmezger, Jurek; Nitschel, Robert; Kraml, Michael; Siemann-Herzberg, Martin; Sánchez-Kopper, Andrés Cell-free protein synthesis, which mimics the biological protein production system, allows rapid expression of proteins without the need to maintain a viable cell. Nevertheless, cellfree protein expression relies on active in vivo translation machinery including ribosomes and translation factors. Here, we examined the integrity of the protein synthesis machinery, namely the functionality of ribosomes, during (i) the cell-free extract preparation and (ii) the performance of in vitro protein synthesis by analyzing crucial components involved in translation. Monitoring the 16S rRNA, 23S rRNA, elongation factors and ribosomal protein S1, we show that processing of a cell-free extract results in no substantial alteration of the translation machinery. Moreover, we reveal that the 16S rRNA is specifically cleaved at helix 44 during in vitro translation reactions, resulting in the removal of the anti-Shine-Dalgarno sequence. These defective ribosomes accumulate in the cell-free system. We demonstrate that the specific cleavage of the 16S rRNA is triggered by the decreased concentrations of Mg2+. In addition, we provide evidence that helix 44 of the 30S ribosomal subunit serves as a point-of-entry for ribosome degradation in Escherichia coli. Our results suggest that Mg2+ homeostasis is fundamental to preserving functional ribosomes in cell-free protein synthesis systems, which is of major importance for cell-free protein synthesis at preparative scale, in order to create highly efficient technical in vitro systems. Artículo científico 2016-01-01T00:00:00Z https://hdl.handle.net/2238/9850 Tracking dipeptides at work-uptake and intracellular fate in CHO culture Sánchez-Kopper, Andres; Becker, Max; Pfizenmaier, Jennifer; Kessler, Christian; Karau, Andreas; Takors, Ralf Market demands for monoclonal antibodies (mAbs) are steadily increasing worldwide. As a result, production processes using Chinese hamster ovary cells (CHO) are in the focus of ongoing intensification studies for maximizing cell-specific and volumetric productivities. This includes the optimization of animal-derived component free (ADCF) cultivation media as part of good cell culture practice. Dipeptides are known to improve CHO culture performance. However, little or even conflicting assumptions exist about their putative import and functionality inside the cells. A set of well-known performance boosters and new dipeptide prospects was evaluated. The present study revealed that dipeptides are indeed imported in the cells, where they are decomposed to the amino acids building blocks. Subsequently, they are metabolized or, unexpectedly, secreted to the medium. Monoclonal antibody production boosting additives like l-alanine-l-glutamine (AQ) or glycyl-l-glutamine (GQ) can be assigned to fast or slow dipeptide uptake, respectively, thus pinpointing to the need to study dipeptide kinetics and to adjust their feeding individually for optimizing mAb production. Artículo científico 2016-01-01T00:00:00Z