Carla A. M. Portugal

BACKGROUND: Limnospira platensis , commonly known as spirulina, holds promise for application as a food ingredient and nutraceutical due to its rich protein and antioxidant content, including chlorophylls, carotenoids and phycocyanin. Despite its potential, the vibrant colour poses a challenge for consumer acceptance, hampering the marketability of spirulina‐based products. To overcome this, innovative strategies are needed to effectively reduce colour while preserving its nutritional value. RESULTS: This study sought to compare the impact of endogenous enzymatic and exogenous horseradish peroxidase ( HRP )‐mediated processes on colour degradation in spirulina extracts. Intrinsic and extrinsic colour degradation experiments were conducted, with and without hydrogen peroxide ( H ₂ O ₂ ) and 4‐hydroxybenzenesulfonic acid ( PSA ) as co‐substrate and analysed using UV –visible spectroscopy. Specifically, the absorbance changes were monitored at 440 and 677 nm, corresponding to chlorophylls a and b , the predominant pigments in spirulina extracts. The degradation of spirulina extracts exhibited a distinct two‐stage pattern. The initial stage, observed within the first hour, displayed a rapid decrease in absorbance, followed by a slower decline in the subsequent stage. In the presence of H ₂ O ₂ , intrinsic degradation caused a gradual absorbance reduction of less than 30% after 24 h. Importantly, the introduction of exogenous factors, including HRP and PSA , resulted in a remarkable 40% absorbance decrease within less than 30 min. CONCLUSION: This substantial enhancement in decoloration efficiency, surpassing the intrinsic metabolic activity, underscores the potential of extrinsic enzymatic approaches. These findings hold promise for addressing the challenge of spirulina extract colouration in products, potentially enabling improved market acceptance and viability. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Cellular Al₂TiO₅–Al₂O₃ composite ceramic monoliths were prepared and tested as a potential stationary phase for process chromatography. The material was characterized by measuring the pore size distribution and hydraulic permeability. The interstitial porosity, the axial dispersion coefficient, and the height equivalent to a theoretical plate were calculated by pulse tests under nonbinding conditions. The surface of the ceramic material was activated with graphene oxide and then functionalized with Cibacron Blue F3GA. The dynamic binding capacity of the functionalized columns was measured in chromatographic cycles by using bovine serum albumin (BSA) as the target molecule. The experiments showed that the proposed monoliths have a well-defined porous structure, leading to particularly interesting flow properties for chromatographic bioseparations, such as very high permeability and convection, as the main mass transport phenomenon. These results are encouraging for a possible future optimization of the functionalization procedure toward the development of efficient convective media for protein purification.

The control of angiogenesis has the potential to be used for regulation of several pathological and physiological processes, which can be instrumental on the development of anticancer and wound healing therapeutical approaches. In this study, mesenchymal stem/stromal cells (MSCs) were seeded on magnetic-responsive gelatin, with or without heparin functionalization, and exposed to a static 0.08 T magnetic field (MF), for controlling their anti-inflammatory and angiogenic activity, with the aim of accelerating tissue healing. For the first time, it was examined how the amount of heparin and magnetic nanoparticles (MNPs) distributed on gelatin scaffolds affected the mechanical properties of the hydrogels and the morphology, proliferation, and secretome profiling of MSCs. The findings demonstrated that the addition of MNPs and heparin affects the hydrogel swelling capacity and renders distinct MSC proliferation rates. Additionally, MF acts as a topographical cue to guide MSCs alignment and increases the level of expression of specific genes and proteins that promote angiogenesis. The results also suggested that the presence of higher amounts of heparin (10 μg/cm³) interferes with the secretion and limits the capacity of angiogenic factors to diffuse through the hydrogel and into the culture medium. Ultimately, this study shows that acellular heparinized hydrogels efficiently retain the angiogenic growth factors released by magnetically stimulated MSCs thus rendering superior wound contraction (55.8% ± 0.4%) and cell migration rate (49.4% ± 0.4%), in comparison to nonheparinized hydrogels (35.2% ± 0.7% and 37.8% ± 0.7%, respectively). Therefore, these heparinized magnetic hydrogels can be used to facilitate angiogenesis in various forms of tissue damage including bone defects, skin wounds, and cardiovascular diseases, leading to enhanced tissue regeneration.

The design of physiologically relevant blood vessel in vitro models has been impaired by the difficulty to reproduce the complex architecture of native blood vessels and the mechanisms mediating key cellular functions within miniaturized perfusable systems. Aiming to simulate blood vessel walls, in this work innovative 2D platforms are designed and patterned with magnetic‐responsive gelatin for enabling in situ co‐culture of mesenchymal stromal cells (MSCs) and human umbilical vein endothelial cells (HUVECs) within confined compartments. The performance of the 2D chips is evaluated based on HUVECs migration, adherence, and angiogenic behavior (proliferation and sprouting), as well as production of Endothelin‐1 (endothelium marker), and compared with the results of 3D single channel models, designed to mimic the morphology of native arteries and veins. The 2D chips obtain better cell adhesion and angiogenic performance, which is attributed to flow profiles and VEGF concentration gradients. Magnetic stimulation is then used as a novel strategy to increase cell sprouting and endothelization ≈1.5 times above the control condition. These bio‐inspired devices advance the exploration of magnetism for a finer convergence to the native vascular conditions in vitro and improved modulation of angiogenesis, showing promising contributions to the development of sophisticated therapeutics for vascular ischemia‐related diseases.

This work explores the unique features of magnetic-responsive hydrogels to obtain liposomal hydrogel delivery platforms capable of precise magnetically modulated drug release based on the mechanical responses of these hydrogels when exposed to an external magnetic field. Magnetic-responsive liposomal hydrogel delivery systems were prepared by encapsulation of 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) multilayered vesicles (MLVs) loaded with ferulic acid (FA), i.e., DPPC:FA liposomes, into gelatin hydrogel membranes containing dispersed iron oxide nanoparticles (MNPs), i.e., magnetic-responsive gelatin. The FA release mechanisms and kinetics from magnetic-responsive liposomal gelatin were studied and compared with those obtained with conventional drug delivery systems, e.g., free liposomal suspensions and hydrogel matrices, to access the effect of liposome entrapment and magnetic field on FA delivery. FA release from liposomal gelatin membranes was well described by the Korsmeyer–Peppas model, indicating that FA release occurred under a controlled diffusional regime, with or without magnetic stimulation. DPPC:FA liposomal gelatin systems provided smoother controlled FA release, relative to that obtained with the liposome suspensions and with the hydrogel platforms, suggesting the promising application of liposomal hydrogel systems in longer-term therapeutics. The magnetic field, with low intensity (0.08 T), was found to stimulate the FA release from magnetic-responsive liposomal gelatin systems, increasing the release rates while shifting the FA release to a quasi-Fickian mechanism. The magnetic-responsive liposomal hydrogels developed in this work offer the possibility to magnetically activate drug release from these liposomal platforms based on a non-thermal related delivery strategy, paving the way for the development of novel and more efficient applications of MLVs and liposomal delivery systems in biomedicine.

This work aims at understanding the attachment mechanisms and stability of proteins on a chromatography medium to develop more efficient functionalization methodologies, which can be exploited in affinity chromatography. In particular, the study was focused on the understanding of the attachment mechanisms of bovine serum albumin (BSA), used as a ligand model, and protein G on novel amine-modified alumina monoliths as a stationary phase. Protein G was used to develop a column for antibody purification. The results showed that, at lower protein concentrations (i.e., 0.5 to 1.0 mg·mL⁻¹), protein attachment follows a 1st-order kinetics compatible with the presence of covalent binding between the monolith and the protein. At higher protein concentrations (i.e., up to 10 mg·mL⁻¹), the data preferably fit a 2nd-order kinetics. Such a change reflects a different mechanism in the protein attachment which, at higher concentrations, seems to be governed by physical adsorption resulting in a multilayered protein formation, due to the presence of ligand aggregates. The threshold condition for the prevalence of physical adsorption of BSA was found at a concentration higher than 1.0 mg·mL⁻¹. Based on this result, protein concentrations of 0.7 and 1.0 mg·mL⁻¹ were used for the functionalization of monoliths with protein G, allowing a maximum attachment of 1.43 mg of protein G/g of monolith. This column was then used for IgG binding–elution experiments, which resulted in an antibody attachment of 73.5% and, subsequently, elution of 86%, in acidic conditions. This proved the potential of the amine-functionalized monoliths for application in affinity chromatography.

The selective recovery of chromium remaining in tannery effluents after the leather tanning process is highly desirable to potentiate its reuse, simultaneously minimizing the ecotoxicity of these effluents. To the best of our knowledge, this work evaluates for the first time the ability of a chitosan-based membrane for selective recovery of chromium from a tannery wastewater by subsequent diafiltration and selective chromium desorption, envisaging their integration after tannery wastewater treatment by reverse osmosis (RO). A polyethersulfone (PES) microfiltration membrane top-coated with a chitosan layer (cs-PES MF022) was used for selective recovery of Cr(III), from concentrate streams obtained by treatment of synthetic and real tannery effluents through reverse osmosis (RO), through a diafiltration process. The diafiltration of the RO concentrates was conducted by an intermittent addition of water acidified to pH 3.6. The prepared cs-PES MF022 membranes were able to retain 97% of the total mass of Cr(III) present in the RO concentrates, from a real tannery effluent, with a selectivity of 4.2 and 5 in reference to NH₄⁺ and Cl⁻, respectively, 12.9 and 14.6 in reference to K and Na, and >45 in reference to Mg, Ca, and S. Such a high selectivity is explained by the preferential adsorption of Cr(III) onto chitosan, and by the relatively high permeability of cs-PES MF022 membranes to the other ionic species. Proof of concept studies were performed to investigate the desorption of Cr(III) at pH 2 and 5.8. A higher Cr(III) desorption degree was obtained at pH 2, leading to a final solution enriched in Cr(III), which may be re-used in tannery operations, thus improving the process economy and reducing the hazardous impact of the effluents discharged by this industry.

Protein crystallization still remains mostly an empirical science, as the production of crystals with the required quality for X-ray analysis is dependent on the intensive screening of the best protein crystallization and crystal’s derivatization conditions. Herein, this demanding step was addressed by the development of a high-throughput and low-budget microfluidic platform consisting of an ion exchange membrane (117 Nafion^® membrane) sandwiched between a channel layer (stripping phase compartment) and a wells layer (feed phase compartment) forming 75 independent micro-contactors. This microfluidic device allows for a simultaneous and independent screening of multiple protein crystallization and crystal derivatization conditions, using Hen Egg White Lysozyme (HEWL) as the model protein and Hg²⁺ as the derivatizing agent. This microdevice offers well-regulated crystallization and subsequent crystal derivatization processes based on the controlled transport of water and ions provided by the 117 Nafion^® membrane. Diffusion coefficients of water and the derivatizing agent (Hg²⁺) were evaluated, showing the positive influence of the protein drop volume on the number of crystals and crystal size. This microfluidic system allowed for crystals with good structural stability and high X-ray diffraction quality and, thus, it is regarded as an efficient tool that may contribute to the enhancement of the proteins’ crystals structural resolution.

The growing prevalence of vascular diseases worldwide has emphasized the need for novel tissue-engineered options concerning the development of vascularized 3D constructs. This study reports, for the first time, the use of external magnetic fields to stimulate mesenchymal stromal cells (MSCs) to increase the production of vascular endothelial growth factor-A (VEGF-A). Polyvinylalcohol and gelatin-based scaffolds, containing iron oxide nanoparticles, were designed for optimal cell magnetic stimulation. While the application of static magnetic fields over 24 h did not impact on MSCs proliferation, viability and phenotypic identity, it significantly increased the production of VEGF-A and guided MSCs morphology and alignment. The ability to enhance MSCs angiogenic potential was demonstrated by the increase in the number of new vessels formed in the presence of MSCs conditioned media through in vitro and in vivo models. Ultimately, this study uncovers the potential to manipulate cellular processes through short-term magnetic stimulation. Graphical abstract