Open Access
Visible-light-driven photocatalytic degradation of organic dyes using a TiO2 and waste-based carbon dots nanocomposite
(Elsevier, 2025-05-20) Sendão, Ricardo M.S.; Algarra González, Manuel; Lázaro-Martínez, Juan; Brandão, Ana T.S.C.; Gil Bravo, Antonio; Pereira, Carlos; Esteves da Silva, Joaquim C.G.; Pinto da Silva, Luís; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Herein we report a visible-light-active photocatalytic nanocomposite (NC50:50) prepared from carbon dots (CDs) and TiO2 nanoparticles, which was applied to the photodegradation of organic dyes in water. The CDs incorporated corn stover, a major agricultural waste, and were prepared via hydrothermal treatment. Using a visible-light irradiation source and the dye methylene blue as a representative of the organic dyes class, we observed that a 374% enhancement of the catalytic performance was achieved by adding CDs relative to bare TiO2. This was possible due to increased visible-light absorption and better photonic efficiency. Tests using reactive species scavengers indicated that three active species (superoxide anion, hydroxyl radicals, and electrons) were responsible for the photodegradation process, differing from bare TiO2 in which only the hydroxyl radical has a relevant role. Photocatalytic degradation was also observed toward Rhodamine B, Orange II and Methyl Orange. Finally, we performed a life cycle assessment (LCA) study to assess and analyse the associated environmental impacts of NC50:50 compared with other alternatives, which revealed that NC50:50 is the alternative resulting in the least environmental impacts. In summary, NC50:50 could, under visible-light irradiation, efficiently remove different organic dyes while incorporating organic waste materials and reducing the impacts associated with their use. We expect that this study provides a base for a more environmentally sustainable design of visible-light-active photocatalysts via waste upcycling.
Open Access
Prediction of protein targets in ovarian cancer using a ru-complex and carbon dot drug delivery therapeutic nanosystems: a bioinformatics and µ-FTIR spectroscopy approach
(MDPI, 2024) Nesic, Maja D.; Dučić, Tanja; Gemović, Branislava; Senćanski, Milan; Algarra González, Manuel; Gonçalves, Mara; Stepic, Milutin; Popovic, Iva; Kapuran, Đorđe; Petkovic, Marijana; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
We predicted the protein therapeutic targets specific to a Ru-based potential drug and its combination with pristine and N-doped carbon dot drug delivery systems, denoted as RuCN/CDs and RuCN/N-CDs. Synchrotron-based FTIR microspectroscopy (µFTIR) in addition to bioinformatics data on drug structures and protein sequences were applied to assess changes in the protein secondary structure of A2780 cancer cells. µFTIR revealed the moieties of the target proteins’ secondary structure changes only after the treatment with RuCN and RuCN/N-CDs. A higher content of α-helices and a lower content of β-sheets appeared in A2780 cells after RuCN treatment. Treatment with RuCN/N-CDs caused a substantial increase in parallel β-sheet numbers, random coil content, and tyrosine residue numbers. The results obtained suggest that the mitochondrion-related proteins NDUFA1 and NDUFB5 are affected by RuCN either via overexpression or stabilisation of helical structures. RuCN/N-CDs either induce overexpression of the β-sheet-rich protein NDUFS1 and affect its random coil structure or interact and stabilise its structure via hydrogen bonding between -NH2 groups from N-CDs with protein C=O groups and –OH groups of serine, threonine, and tyrosine residues. The N-CD nanocarrier tunes this drug’s action by directing it toward a specific protein target, changing this drug’s coordination ability and inducing changes in the protein’s secondary structures and function.
Open Access
Nitrogen doped carbon dots as a photocatalyst based on biomass: a life cycle assessment
(Elsevier, 2023) Rodríguez-Carballo, Gabriela; Moreno-Tost, Ramón; Fernandes, Sónia; Esteves da Silva, Joaquim C.G.; Pinto da Silva, Luís; Castro Galiano, Eulogio; Algarra González, Manuel; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The effectiveness of various transition metal phosphate-based acid catalysts, including vanadium and niobium, in the hydrothermal synthesis of carbon dots (CDs), has been assessed. Two sources of carbohydrates were employed for this: commercial xylose and liquor of xylose produced by processing olive pits. Catalysts were identified using the NH3-TPD, DTA/TG, XRD, and XPS techniques. The reaction was conducted for 4 h at a temperature of 180 °C. The existence of such nanoparticles, regardless of the carbohydrate source, was confirmed by an analysis of the features and characteristics of CDs nanoparticles. N-doped CDs with increased fluorescence were also created at the same time using a similar hydrothermal technique, and their photocatalytic activity was investigated. A Life Cycle Assessment (LCA) was conducted for both syntheses with the goal of comparing the environmental effects of the synthesis from commercial xylose to the synthesis from biomass. It was revealed that, although energy is the primary driver of both synthesis pathways' effect categories, the fundamental variations that seem to determine their relative sustainability are connected to the nature of the carbon precursor. Regarding the latter, it is determined that electricity has the greatest environmental impact.
Open Access
Synergistic enhancement of targeted wound healing by near-infrared photodynamic therapy and silver metal-organic frameworks combined with S- or N-doped carbon dots
(MDPI, 2024) Nesic, Maja D.; Popovic, Iva; Zakula, Jelena; Koricanac, Lela; Filipovic Trickovic, Jelena; Valenta Šobot, Ana; Jiménez, María Victoria; Algarra González, Manuel; Dučić, Tanja; Stepic, Milutin; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The literature data emphasize that nanoparticles might improve the beneficial effects of near-infrared light (NIR) on wound healing. This study investigates the mechanisms of the synergistic wound healing potential of NIR light and silver metal–organic frameworks combined with nitrogen- and sulfur-doped carbon dots (AgMOFsN-CDs and AgMOFsS-CDs, respectively), which was conducted by testing the fibroblasts viability, scratch assays, biochemical analysis, and synchrotron-based Fourier transform infrared (SR-FTIR) cell spectroscopy and imaging. Our findings reveal that the combined treatment of AgMOFsN-CDs and NIR light significantly increases cell viability to nearly 150% and promotes cell proliferation, with reduced interleukin-1 levels, suggesting an anti-inflammatory response. SR-FTIR spectroscopy shows this combined treatment results in unique protein alterations, including increased α-helix structures and reduced cross-β. Additionally, protein synthesis was enhanced upon the combined treatment. The likely mechanism behind the observed changes is the charge-specific interaction of N-CDs from the AgMOFsN-CDs with proteins, enhanced by NIR light due to the nanocomposite’s optical characteristics. Remarkably, the complete wound closure in the in vitro scratch assay was achieved exclusively with the combined NIR and AgMOFsN-CDs treatment, demonstrating the promising application of combined AgMOFsN-CDs with NIR light photodynamic therapy in regenerative nanomedicine and tissue engineering.
Open Access
Low-cost Titania-Hydroxyapatite (TiHAp) nanocomposites were synthesized for removal of methylene blue under solar and UV irradiation
(Elsevier, 2025-07-01) Latifi, Souhayla; Saoiabi, Sanaa ; Alanazi, Mohammed M. ; Boukra, Omar ; Krime, Anas ; El Hammari, Larbi; Azzaoui, Khalil; Hammouti, Belkheir; Hanbali, Ghadir; Jodeh, Shehdeh; Saoiabi, Ahmad ; Sabbahi, Rachid ; Algarra González, Manuel; Abidi, Noureddine ; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Water pollution from industrial dyes like methylene blue (MB) poses significant environmental and health risks due to their toxicity and persistence. In this study, we synthesized a novel titania-hydroxyapatite (TiHAp) nanocomposite via a low-cost, scalable sol-gel method to address these challenges. The composite was comprehensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Photocatalytic degradation of MB under both solar and UV irradiation was evaluated using kinetic (pseudo-first-order and pseudo-second-order) and isotherm (Langmuir and Freundlich) models, demonstrating hydroxyapatite's key role in enhancing adsorption and facilitating effective interactions with the catalyst. Under optimized conditions, the TiHAp nanocomposite achieved 96.58 % degradation of MB at an initial concentration of 120 mg/L and retained over 95 % activity after five reuse cycles. These results illustrate that the synergistic combination of TiO₂'s photocatalytic activity and HAp's adsorptive capacity produces a highly effective composite for degrading organic pollutants. The study underscores the potential of TiHAp nanocomposites as sustainable materials for wastewater treatment applications, while future work will explore their performance against a broader range of contaminants under realistic environmental conditions.
Open Access
Diverse methods with stereoselective induction in the asymmetric Biginelli reaction
(MDPI Publishing, 2024-08-15) Díaz Fernández, Marcos; Algarra González, Manuel; Calvo Losada, Saturnino; Quirante, José Joaquín; Sarabia, Francisco; Pino-González, María Soledad; Institute for Advanced Materials and Mathematics - INAMAT2
The relevance of the asymmetric Biginelli reaction (ABR) has been increased in this century, due to the pharmacological application of its products. This review focuses predominantly on articles published in the period from 2015 to 2024 on asymmetric synthetic advances in the formation of dihydropyrimidinones (DHPMs), dihydropyrimidinethiones (DHPMTs), and related compounds. The relevant bibliography on general processes in the Biginelli reaction and some methods of separation of isomers have also been referenced.
Open Access
Green chitosan: thiourea dioxide cleaning gel for manganese stains on granite and glass substrates
(Springer Nature, 2021) Campos, Bruno; Marco, Alexandra; Cadeco, Guilhermina; Freire-Lista, David M.; Silvestre-Albero, Joaquín; Algarra González, Manuel; Vieira, Eduarda; Pintado, Manuela; Moreira, Patricia; Ciencias; Zientziak
The cleaning or removal of manganese stains on Cultural Heritage has not been much tested or successful so far. The aim of this article was to assess a new green cleaning gel for Mn-rich black-blue stains on different substrates. The black-blue stains were characterized at optical and chemical level through colour-related data, optical microscope, FTIR, XRF and XPS. Mn-stained granite found on historical churches at Vila Real (North of Portugal) and glass jars of Leclanché cells, belonging to the ISEP's Museum (Portugal) collection, were the ideal case studies to test the efficiency of chitosan: thiourea dioxide (TD) cleaning gel. TD proved to be the best candidate to reduce insoluble manganese oxides, over Hydroxylamine Hydrochloride and Hydroxymethanesulfinic Acid. Cleaning assays performed on stained granite samples collected at a historical quarry and in situ application on stained granite churches allowed removal of the stains to a satisfactory level. Similar results were obtained on stained glass jars.
Embargo
Testing of black-carrots-derived fluorescence imaging and anti-metastatic potential
(Elsevier, 2024) Algarra González, Manuel; Carrillo, Celia; Nesic, Maja D.; Filipovic Trickovic, Jelena; Zakula, Jelena; Koricanac, Lela; Jiménez-Jiménez, José; Rodríguez-Castellón, Enrique; Bandosz, Teresa J.; Petkovic, Marijana; Soto, Juan; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
This paper explains the basis for the excitation energy-independent fluorescence emission of biomass-derived carbon dots (CDs) and shows that these CDs have excellent anti-melanoma and anti-metastatic potential. Additionally, we demonstrate that the black carrots´-derived CDs can be exploited as cell cycle-sensing agents, because of the interaction with chromatin material. Besides their optical properties, fluorescent CDs have gained increased attention for image-guided cancer treatment due to their water solubility, environmental friendliness, affordability, ease of synthesis, and primary biocompatibility. CDs have excellent photostability, determined by their precursors and synthesis pathways. In this study, CDs with chemically homogenous surface functional groups were made using a hydrothermal technique from black carrot extract, an anthocyanin-rich substance derived from biomass. The anti-cancer and anti-metastatic properties of black carrot-derived CDs can be attributed to flavylium cations on the surface, spherical forms, and high water dispersibility. Most importantly, these CDs demonstrate a stable emission at a single wavelength, 612 nm, independent of the excitation energy, which we have explained theoretically for the first time.
Open Access
Efficient and scalable gene delivery method with easily generated cationic carbon dots
(BMC, 2024) Algarra González, Manuel; González-Muñoz, Elena; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Gene delivery is a complex process with several challenges when attempting to incorporate genetic material efficiently and safely into target cells. Some of the key challenges include not only efficient cellular uptake and endosomal escape to ensure that the genetic material can exert its effect but also minimizing the toxicity of the delivery system, which is vital for safe gene delivery. Of importance, if gene delivery systems are intended for biomedical applications or clinical use, they must be scalable and easy and affordable to manufacture to meet the demand. Here, we show an efficient gene delivery method using a combination of carbon dots coated by PEI through electrostatic binding to easily generate cationic carbon dots. We show a biofunctional approach to generate optimal cationic carbon dots (CCDs) that can be scaled up to meet specific transfection demands. CCDs improve cell viability and increase transfection efficiency four times over the standard of PEI polyplexes. Generated CCDs enabled the challenging transfection protocol to produce retroviral vectors via cell cotransfection of three different plasmids into packing cells, showing not only high efficiency but also functionality of the gene delivery, tested as the capacity to produce infective retroviral particles.
Open Access
Synthesis of hydroxyapatite/polyethylene glycol 6000 composites by novel dissolution/precipitation method: optimization of the adsorption process using a factorial design: DFT and molecular dynamic
(BMC, 2023) Azzaoui, Khalil; Jodeh, Shehdeh; Mejdoubi, E.; Hammouti, B.; Taleb, M.; Ennabety, G.; Berisha, Avni; Aaddouz, M.; Youssouf, M. H.; Shityakov, S.; Sabbahi, Rachid; Algarra González, Manuel; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
In this work, we presented a synthesis of a composite based on HAp and PEG 6000 using a new method of synthesis dissolution precipitation to be applied for application of wastewater purification from toxic metal ions. Multiple characterization methods were used to analyze the morphology and the structure of the well-prepared compounds including FT-IR, Raman, XRD, XPS, TGA and SEM were used to conduct a composite analysis. The adsorption effectiveness of this analysis towards Pb2+ and various other hazardous metal ions found in sewage was assessed. Batch experiments were conducted to optimize the various operational parameters including adsorbent dose, temperature, pH, contact time, and initial concentration. The Langmuir isotherm was used to fit the data, and it predicted monolayer adsorption with a maximum capacity of 67 mg g−1 for HAP PEG600 and 60 mg g−1 for HAp. A pseudo-second-order equation fits the adsorption process well (0.961–0.971). The thermodynamic data support the spontaneous metal bonding to the composite receptor sites. Theoretical calculations showed that the interaction strength is very strong and gets stronger when the PEG6000 is deprotonated. The results presented here are supported by evidence acquired from experiments. Theoretical computation using Monte Carlo (MC) and Molecular Dynamic (MD) simulation models showed excellent affinity of prepared foams for the model ion Pb2+ with highly negative adsorption energy values indicating vigorous interactions of Pb2+ with the adsorbate surfaces.