Publications

Hydrogen peroxide (H2O2) is a key reactive species in biological, environmental, and industrial systems, creating a demand for robust, sustainable, and tunable sensing materials. Here, we report a green, simple in situ strategy to fabricate magnetically responsive catalytic chitosan-agarose hydrogels with tunable nano-microstructure and transport properties. Fe3O4 nanoparticles are generated directly within chitosan-agarose hydrogel networks using chloride- and sulfate-based iron precursors, enabling controlled modulation of nanoparticle size distribution, crystallographic plane exposure, and magnetic response without surfactants or organic solvents. We demonstrate that the choice of iron precursor governs nanoparticle nucleation kinetics and interfacial interactions with the biopolymer matrix, leading to distinct microstructural architectures that directly impact mechanical stiffness, swelling behavior, and magnetic properties. Importantly, the embedded Fe3O4 nanoparticles exhibit intrinsic peroxidase-like catalytic activity, allowing the hydrogels to function as a solid-state nanozyme platform for colorimetric H2O2 detection. Beyond static performance, we show that external magnetic fields dynamically reconfigure hydrogel properties providing reversible, field-controlled regulation of catalytic activity and sensing sensitivity. The optimized hydrogels display linear H2O2 detection up to 100 mu M with sub-micromolar detection limits (< 1 mu M), while offering key materials-level advantages including reusability, structural stability, and facile magnetic manipulation. This work establishes a simple approach for integrating nanozyme catalysis, magnetic actuation, and sustainable biopolymer matrices, offering a broadly applicable platform for magnetically tunable catalytic materials and responsive sensing systems.

JTD Keywords: Chitosan-agarose nanocomposites, Colorimetric detection, Fe3o4 nanozymes, Nanoparticles, Peroxidase-like activity, Sustainable biosensors

Bioelectrical cues are essential for cardiac function and regeneration, yet current electrostimulation strategies rely on invasive electrodes that limit spatial control and clinical translation. Here, we report magnetoelectric nanocomposite hydrogels that combine core-shell CoFe2O4@BiFeO3 magnetoelectric nanoparticles (ME NPs) with a photo-cross-linked methacrylated gelatin (GelMA) network, enabling wireless electroactivity through externally applied magnetic fields within a soft, biomimetic three-dimensional scaffold. Structural and physicochemical analyses confirmed the successful synthesis of crystalline core-shell ME NPs with strong interfacial coupling, as demonstrated by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and magnetic hysteresis measurements showing exchange bias effects. Homogeneous incorporation of ME NPs within GelMA produced highly porous and interconnected hydrogels, as revealed by scanning electron microscopy and microcomputed tomography. The presence of nanoparticles reduced equilibrium swelling and refined pore architecture, suggesting increased effective cross-linking density and nanoparticle-polymer interactions. Mechanical testing showed soft elastomeric behavior with compressive moduli compatible with cardiac tissue. Under dynamic magnetic stimulation, magnetoelectric hydrogels significantly enhanced cardiac cell viability, proliferation, and morphological organization compared with pristine GelMA controls. After 10 days, the metabolic activity of cells cultured on GelMA-ME NP hydrogels under stimulation was approximately 3-fold higher than that of unstimulated GelMA. These results demonstrate that magnetoelectric hydrogels provide an effective platform for wireless electrostimulation, offering promising opportunities for cardiac tissue engineering and implantable bioelectronic therapies without wired electrodes.

JTD Keywords: Cardiac tissue engineering, Core-shell nanoparticles, Fields, Gelma hydrogels, Magnetoelectric nanocomposites, Tissue, Wireless electrostimulation

The accumulation of microplastics (& micro;Pls) in ecosystems has become a serious environmental concern. Despite increasing awareness, the development of efficient technologies for their removal and remediation remains a major challenge. Herein, we investigate the photocatalytic degradation of polypropylene (PP) & micro;Pls using nanocomposite catalysts composed of permanently polarized hydroxyapatite microparticles (pp-HAp) and rutile TiO2 nanoparticles (TiO2 NPs). pp-HAp, a macroporous bioceramic, is known for its ability to convert gases (CO2 or/and N2) into small value-added chemical products. While pp-HAp serves both as the substrate and thermocatalytic part of the composite, TiO2 NPs are incorporated as the photocatalytic component. A series of XTiO2/ pp-HAp photocatalyts, where X represents the weight percentage of TiO2 (X = 2.5, 5, 10 and 20), were prepared applying a thermal stimulated polarization treatment. The resulting materials show no formation of undesirable calcium titanate. After thorough chemical and physical characterization, the photocatalytic performance of the XTiO2/pp-HAp in the degradation of PP-& micro;Pls was evaluated. Under 1 sun irradiation, the process is selective toward ethanol, which indicates the cleavage of consecutive C-C bonds along the PP chains, with the highest yield obtained for 2.5TiO2/pp-HAp. When the irradiation intensity decreases (0.5 sun), ethanol and isopropanol are produced, suggesting a reduction in the efficiency of the C-C cleavage. In all cases, the nanocomposite catalysts exhibit significantly higher yields than TiO2 NPs or pp-HAp individually, which indicates cooperative electronic effects between both components. Regarding selectivity, in addition to the solar irradiation, the TiO2: pp-HAp ratio also determines which product is obtained. Within the framework of circular economy, our strategy yields added-value chemical products from PP waste using only sunlight and an environmentally friendly catalyst.

JTD Keywords: Anatase, Heterogeneous catalysis, Microplastics, Microplastics removal, Nanocomposites, Photocatalysts, Polypropylene photodegradation, Water treatment plants

Electrically polarized amorphous silica (aSiO2) is demonstrated to be an efficient and viable metal-free heterogeneous catalyst for the conversion of CO2 into valuable chemical products. The catalyst was prepared applying a thermoelectric polarization process in air to commercially available aSiO2 nanoparticles. Four polarization temperatures were assayed (150, 500, 800 and 1000 degrees C), the larger structural and chemical changes induced by the polarization treatment being observed at 150 and 500 degrees C. The polarization at such temperatures reduced considerably the electrical resistance of calcined aSiO2, while no significant change was detected at 800 and 1000 degrees C. Polarized aSiO2 was tested as heterogeneous catalysts for the reaction of CO2 with water at mild reaction conditions (120 degrees C, 6 bar of CO2, 40 mL of water, 72 h). The highest catalytic activity was observed with aSiO2 polarized at 150 degrees C, which was attributed to the structural defects induced during the thermoelectric polarization treatment. Thus, CO2 was converted into a mixture of formic acid (39.9%), acetic acid (44.4%) and dioxane (15.7%). Although the catalytic process was not selective, the yields were not only very high but also allowed obtaining a significant amount of dioxane, a product with four carbon atoms, which is very unusual in processes catalyzed by polarized ceramics. In summary, polarized aSiO2 can be used as a sustainable and low-cost raw material to prepare metal-free catalysts by means of a thermoelectric polarization process at 150 degrees C. This catalyst is capable of capturing CO2 to produce valuable chemical products by applying mild reaction conditions.

JTD Keywords: Alloy, Atom, Basis-sets, Bone, Catalysts, Hydroxyapatite, Nanocomposites, Nanoparticles, Oxidation, Performance

Nanowire-based nanocomposite materials are being developed as transparent and flexible electrodes or as stretchable conductors and dielectrics for biosensing. Here, we theoretically investigate the use of scanning dielectric microscopy (SDM) to characterize these materials in a nondestructive way, with a special focus on the achievable spatial resolution and the possibility of detection of the capacitive coupling between nearby nanowires. Numerical calculations with models involving single and multiple buried nanowires have been performed. We demonstrate that the capacitance gradient spread function of a single buried nanowire consists of a modified Lorenzianan with a cubic decay. We show that the achievable spatial resolution can be determined with good accuracy with the help of this spread function. It is shown that, in general, the spatial resolution worsens when any system parameter decreases the maximum of the nanowire spread function or increases its width, or both. Finally, we show that SDM measurements are also sensitive to the capacitive coupling between nearby nanowires. This latter result is of utmost relevance since the macroscopic electric properties of nanowire nanocomposites largely depend on the electric interaction between nearby nanowires. The present results show that SDM can be a valuable nondestructive subsurface characterization technique for nanowire nanocomposite materials.

JTD Keywords: depth, electrodes, nanocomposites, nanowires, sdm, spatial resolution, subsurface, tomography, Capacitive coupling, Force microscopy, Nanocomposites, Nanowires, Sdm, Spatial resolution, Subsurface

Polymer nanocomposite materials based on metallic nanowires are widely investigated as transparent and flexible electrodes or as stretchable conductors and dielectrics for biosensing. Here we show that Scanning Dielectric Microscopy (SDM) can map the depth distribution of metallic nanowires within the nanocomposites in a non-destructive way. This is achieved by a quantitative analysis of sub-surface electrostatic force microscopy measurements with finite-element numerical calculations. As an application we determined the three-dimensional spatial distribution of ?50 nm diameter silver nanowires in ?100 nm-250 nm thick gelatin films. The characterization is done both under dry ambient conditions, where gelatin shows a relatively low dielectric constant, ?r ? 5, and under humid ambient conditions, where its dielectric constant increases up to ?r ? 14. The present results show that SDM can be a valuable non-destructive subsurface characterization technique for nanowire-based nanocomposite materials, which can contribute to the optimization of these materials for applications in fields such as wearable electronics, solar cell technologies or printable electronics. © The Royal Society of Chemistry.

JTD Keywords: composite, constant, electrodes, mode, nanostructures, objects, progress, subsurface, tomography, Composite materials, Dielectric materials, Electric force microscopy, Electrostatic force, Force microscopy, Low dielectric constants, Nanocomposites, Numerical calculation, Polymer nanocomposite, Printable electronics, Scanning dielectric microscopy, Silver nanowires, Solar cell technology, Stretchable conductors, Subsurface characterizations, Transparent electrodes, Wearable technology

Bioactive nanocomposite scaffolds with cell-adhesive surface have excellent bone regeneration capacities. Fibronectin (FN)-immobilized nanobioactive glass (nBG)/polycaprolactone (PCL) (FN-nBG/PCL) scaffolds with an open pore architecture were generated by a robotic-dispensing technique. The surface immobilization level of FN was significantly higher on the nBG/PCL scaffolds than on the PCL scaffolds, mainly due to the incorporated nBG that provided hydrophilic chemical-linking sites. FN-nBG/PCL scaffolds significantly improved cell responses, including initial anchorage and subsequent cell proliferation. Although further in-depth studies on cell differentiation and the in vivo animal responses are required, bioactive nanocomposite scaffolds with cell-favoring surface are considered to provide promising three-dimensional substrate for bone regeneration.

JTD Keywords: Bone scaffolds, Cell response, Fibronectin, Nanobioactive glass, Nanocomposites, Polycaprolactone, Bone, Cell proliferation, Cells, Cytology, Glass, Nanocomposites, Polycaprolactone, Robotics, Bone scaffolds, Bone tissue engineering, Cell response, Fibronectin, Fibronectin immobilizations, Nano bioactive glass, Nanocomposite scaffolds, Three-dimensional substrates, Scaffolds (biology)