Search Results (187)

The present study investigates the synthesis and dispersibility process of iron oxide nanoparticles using laser pyrolysis with isopropanol vapors as a sensitizer agent. Similar to previous experiments (iron oxide nanoparticles synthesized by laser pyrolysis using ethylene as sensitizer gas), iron pentacarbonyl (Fe(CO)₅) was employed as an iron precursor; however, instead of the classic ethylene, isopropanol was chosen as a sensitizer, which indicated beneficial features (especially enhanced dispersibility in water) in the as-synthesized nanoparticles. Structural and elemental analysis confirmed the size range of the nanoparticles (nanometric), with crystallite sizes under 10 nm. Both raw nanoparticles, as well as the oleic acid stabilized ones, exhibited excellent colloidal stability in both water and organic fluids (Toluene, Chloroform, and DMSO): around 100 nm hydrodynamic diameter and more than 40 mV for zeta potential. The study highlights the advantages of using isopropanol as a sensitizer in the production of high-purity iron oxide nanoparticles from laser pyrolysis, particles that showcase superior dispersibility and functionalization potential. Full article

Small interfering RNAs (siRNAs) provide strong therapeutic potential due to their efficient gene-silencing properties; however, their instability limits clinical application. Nanoparticle carriers may overcome this problem; in particular, magnetic nanoparticles show great promise as they can be directed to the target sites by external magnetic fields, thus improving delivery efficiency and reducing off-target effects. In addition, magnetic nanoparticles offer a novel nanoplatform for theranostic applications, integrating siRNA delivery with magnetic resonance imaging and magnetic hyperthermia for synergistic diagnostic and therapeutic advantages. The present work reports the development of a novel platform based on biomimetic magnetic nanoparticles made of Fe(II)/Fe(III)-doped apatite (FeHA) nucleated and grown in the presence of cherry and pomegranate leaf extracts to enhance the colloidal stability and make it suitable for nucleic acid delivery under the guidance of magnetic fields. This approach allowed the obtention of FeHA suspension with increased negative zeta potential leading to very good stability. In addition, the functionalization with natural extracts conferred antioxidant properties also favoring the maintenance of the Fe(III)/Fe(II) ratio in the apatitic structure, inducing the superparamagnetic properties. To evaluate the delivery capability of the system, a model GAPDH-targeting siRNA molecule was employed. Its interaction with the nanoplatform was characterized by assessing loading capacity and release kinetics, which were further interpreted using mathematical modeling to elucidate the underlying release mechanisms. Full article

Background: Radioactive colloids are considered the standard of care for sentinel lymph node (SLN) detection. An alternative detection method using superparamagnetic iron oxide (SPIO) nanoparticles is well documented in breast cancer but poorly studied for gynecological tumors, including vulvar cancer (VC). Objective: Our aim was to evaluate the feasibility, accuracy, and safety of SPIO nanoparticles for SLN mapping in patients with VC as a stand-alone technique compared with the combination of two methods: the standard of care using a radioactive isotope (technetium-99; Tc-99) and SPIO as a new tracer. Methods: We conducted a prospective and observational study of SLN mapping in patients with stage IB VC and tumor size ≤ 4 cm. We calculated detection and malignancy rates per patient and per groin in both study groups. During the 36-month follow-up, the groin recurrence rate was estimated for positive and negative SLNs. Kaplan–Meyer curves were used to analyze the probability of survival, depending on disease-free survival. Results: A total of 110 groins assessed by SLN in 60 patients included in this study were analyzed (70 groins from 40 patients in the group with a single tracer and 40 groins from 20 patients in the group of combined tracers). At least one sentinel lymph node was detected in every patient while the bilateral detection rate was 92.3% for the SPIO group and 88.2% for the Tc-99 and SPIO group. The groin detection rate was 94.3% and 90%, respectively. SLN mapping failure was similar in both groups (2.8% and 2.5%, respectively). During a 3-year follow-up, the isolated groin recurrence rate was 2.1% for negative groins and for disease-free survival it was 28.9 months in the combined tracer group versus 32.8 months in the SPIO group. The Kaplan–Meyer curves showed the increased probability of survival for the SPIO group (87.5%); however, it was insignificant. Conclusions: SLN mapping using the SPIO technique in patients with VC is non-inferior to the combined SPIO and Tc-99 method. Full article

Nutrient cycling has barely been studied in acidic environments and may have an important influence on the evolution of the microbial communities. In this research, we studied nutrient sources and fluxes in acidic metal-mine pit lakes to evaluate their relationship with the lakes’ microbial ecology. Nutrient concentrations (including phosphorus, nitrogen, and dissolved inorganic carbon) increase with depth in all the studied pit lakes. Phosphorus comes mainly from the leaching of the host rock and is rapidly scavenged from the aqueous phase in the oxygenic and Fe(III)-rich mixolimnion due to adsorption on ferric precipitates (schwertmannite, jarosite), which leads to an important P-limitation in the photic zone. Below the chemocline, however, the sum of phosphorus inputs (e.g., settling of algal biomass, desorption from the ferric compounds, microbial reduction of Fe(III)-sediments) sharply increases the concentration of this element in the anoxic monimolimnion. Nitrogen is very scarce in the host rocks, and only a limited input occurs via atmospheric deposition followed by N-uptake by algae, N-fixation by acidophilic microorganisms, sedimentation, and organic matter degradation in the sediments. The latter process releases ammonium to the anoxic monimolimnion and allows some nitrogen cycling in the chemocline. Soluble SiO₂ in the mixolimnion is abundant and does not represent a limiting nutrient for diatom growth. Differences in phytoplankton biomass and extent of bacterial sulfate reduction between relatively unproductive lakes (San Telmo) and the more fertile lakes (Cueva de la Mora) are likely caused by a P-limitation in the former due to the abundance of ferric iron colloids in the water column. Our results suggest that phosphorus amendment in the photic zone could be an efficient method to indirectly increase acidity-consuming and metal-sequestering bacterial metabolisms in these lakes. Full article

Comprehensive studies of Famille rose porcelains, particularly ruby-back pieces, are rare and have generally not addressed the vibrational signatures arising from gold nanoparticles. Due to the high cultural and material value of these artifacts, a strictly non-invasive approach combining X-ray fluorescence (XRF) and Raman (micro-)spectrometry must be employed. If the conservation of porcelain does not pose any difficulties, fakes exist and they must be identified. Preliminary studies show that the presence of metal nanoparticles generates plasmon-related fluorescence. Our results confirm that plasmon fluorescence is more effective than pXRF for detecting colloidal gold, whereas pXRF efficiently identifies associated elements such as arsenic, tin, and, newly observed, antimony; the presence of iron is difficult to demonstrate due to its ubiquitous occurrence. Yellow and green hues, distinct from those produced by Cu²⁺ ions alone, are mainly due to simple tin yellow (PbSnO₃), while the cobalt used originates from a mixture of European smalt (rich in arsenic and potassium) and Asian ores (rich in manganese). Minimal variability was observed among egg-shell porcelains with similar decorations and dimensions, suggesting a common workshop or standardized raw materials and procedures. Two other egg-shell plates employ a different gold preparation technique (addition of Sn and Sb rather than As), which is visually evident in the ruby color. Full article

Superparamagnetic iron oxide nanoparticles (SPIONs) with sizes below 10 nm are biocompatible and non-toxic, making them promising for biomedical applications. To prevent their agglomeration and enhance their functionality, the nanoparticles were coated with citric acid (CA), which modifies the surface charge, improves dispersion stability, and facilitates biomedical use. In this work, a modular flow-through microreactor system was employed to synthesize and coat the nanoparticles in a single, continuous two-step process. The system enables precise control over temperature and mixing, ensuring uniform reaction conditions and minimizing hot spots. The synthesized Fe₃O₄ nanoparticles exhibited an average crystallite size of ~5 nm (XRD) and particle sizes of 4–6 nm (TEM). FTIR analysis confirmed the successful surface functionalization with CA, while TGA indicated a coating mass fraction of approximately 4–20 wt%, increasing with higher CA concentration. Zeta potential measurements revealed strong colloidal stability, with values around −35 mV at pH 6.5. Among the tested CA concentrations, the sample with a molar ratio of Fe₃O₄:CA = 1:0.25 exhibited the most favorable properties, including narrow size distribution and improved dispersion stability. These findings demonstrate that the continuous modular flow approach enables the reproducible synthesis of highly stable, sub-10 nm CA-coated SPIONs, offering promising potential for biomedical applications, particularly as magnetic resonance imaging (MRI) contrast agents. Full article

Late-Archean seawater functioned as a vast, redox-tuned colloidal system for which its kinetics were largely governed by the surface chemistry of silica–iron nanoparticles. By reproducing Archean seawater (≈0.7 M ionic strength, 25 °C) in laboratory anoxic-to-mildly oxic reactors, the ζ potential (zeta-potential(ζ)) of silica–iron nanoparticles was investigated, and we tracked how transient O₂ pulses (≤9 mg L⁻¹) regulated it. The zeta (ζ) potential was applied as the key diagnostic parameter to quantify both the sign of the ζ potential and the colloidal stability of simulated silica–iron particles in dispersion. Under strictly anoxic conditions, silica colloids (SiO₂(aq)) exhibit a persistently negative ζ potential (ζ ≈ −25 mV) in the simulated seawater (pH 6.5), arising from deprotonated silanol groups (≡Si–O⁻). Upon the addition of Fe²⁺, the inner-sphere complexation of ferrous ions on SiO₂ colloids partially replaces ≡Si–O⁻ with ≡Si–O–Fe⁺/≡Si–O–Fe–OH sites; the net negative charge density at the outer Stern plane nevertheless increases, and the ζ potential shifts from −25 mV to −30 mV. As the simulated seawater was oxygenated, the dissolved and surface-bound Fe²⁺ ions were oxidized to Fe³⁺, causing the ζ potential to exceed −30 mV. This study demonstrates that Fe²⁺–silica interactions generate electrostatic destabilization, suspending micron-scale aggregates and thus modulating the solubility and speciation of SiO₂ in early oceans. Also, transient micro-oxic pulses are shown to shift silica–iron colloids between metastable aggregation and dispersion by modulating their ζ potential. Subsequently, AFM and TEM were used to characterize the morphological changes in the colloidal particles from the liquid state to the dry state. Furthermore, infrared and XPS analyses were conducted on the colloidal samples. These findings provide certain reference significance for reconstructing the chemical evolution process of seawater in the Late-Archean period and for understanding the factors influencing the silicon–iron cycle of seawater in the Late-Archean era. Full article

It has been demonstrated that iron-reducing bacteria (IRB) Acidiphilium cryptum JF-5 (Alphaproteobacteria) could release arsenic from secondary iron oxyhydroxides in mine areas. This study used injecting IRB technology to carry out arsenic sequestration experiments aimed at alleviating arsenic pollution. Temperature and acetate were found to enhance arsenic release from amorphous arsenic-containing hydroxides. A suitable temperature (35 °C) increased the release of arsenic(III) and arsenic(V) by more than 1.9–2.5 and 1.1–1.3 times, respectively. The addition of acetate increased arsenic(III) and arsenic(V) release by more than 2.8–6.1 and 1.1–1.3 times, respectively, compared to the control group. After injecting IRB into amorphous arsenic-containing hydroxide sediment, arsenic associated with particles/colloid was reductively released with aqueous arsenic(III) and arsenic(V), which account for 4%–334% of aqueous arsenic(III) and 6%–332% of aqueous arsenic(V), respectively. Results from the suspension solid also showed that the average values for the lower and upper sites are 131 mg/L and 118 mg/L, respectively. These suspension solids contain rich iron. The effectiveness of this IRB-assisted arsenic release technology became better under suitable temperature (35 °C) than at low temperature (8 °C) due to biological activity. These results suggest that microbially assisted reduction using iron-reducing bacteria may effectively release arsenic by sequestrating arsenic as aqueous and particle/colloidal phases. Full article

Background: Glioblastoma multiforme (GBM) is an aggressive primary brain malignancy associated with poor prognosis and limited therapeutic options. Nanoparticle-based drug delivery systems provide a promising strategy to enhance treatment efficacy by circumventing barriers such as the blood–brain barrier. This study was conducted to synthesize, characterize, and evaluate the in vitro anticancer potential of andrographolide–iron oxide nanoparticles (AG-IONPs) against GBM cells. Methods: Iron oxide nanoparticles (IONPs) were synthesized through co-precipitation and subsequently functionalized with andrographolide. Morphology, size, and surface charge were assessed by transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential analysis. Functionalization was confirmed by Fourier-transform infrared spectroscopy (FTIR) and UV–Vis spectroscopy. Nanoparticle stability was monitored over three months. Cytotoxicity toward DBTRG-05MG cells was evaluated using MTT assays at 24, 48, and 72 h, while anti-migratory effects were determined using scratch-wound assays. Results: TEM analysis revealed nearly spherical IONPs (7.0 ± 0.15 nm) and AG-IONPs (13.5 ± 1.25 nm). DLS indicated an increased hydrodynamic diameter following functionalization, while zeta potential values decreased from +21.22 ± 1.58 mV to +8.68 ± 0.87 mV. The successful incorporation of andrographolide was confirmed by FTIR and UV–Vis spectra. AG-IONPs demonstrated excellent colloidal stability for up to three months. Cytotoxicity assays revealed a dose- and time-dependent decrease in cell viability, with LC₅₀ values declining from 44.01 ± 3.23 μM (24 h) to 15.82 ± 2.30 μM (72 h). Scratch-wound assays further showed significant inhibition of cell migration relative to untreated controls. Conclusions: AG-IONPs exhibit favorable physicochemical properties, long-term stability, and potent anti-proliferative and anti-migratory effects against GBM cells in vitro. These findings support their potential as a multifunctional therapeutic platform, warranting further preclinical investigation. Full article

Iron oxide nanoparticles (IONPs) have emerged as key materials in magnetic hyperthermia (MH), a minimally invasive cancer therapy capable of selectively inducing apoptosis, ferroptosis, and other cell death pathways while sparing surrounding healthy tissue. This review synthesizes advances in the design, functionalization, and biomedical application of magnetic nanoparticles (MNPs) for MH, highlighting strategies to optimize heating efficiency, biocompatibility, and tumor targeting. Key developments include tailoring particle size, shape, and composition; doping with metallic ions; engineering multicore nanostructures; and employing diverse surface coatings to improve colloidal stability, immune evasion, and multifunctionality. We discuss preclinical and clinical evidence for MH, its integration with chemotherapy, radiotherapy, and immunotherapy, and emerging theranostic applications enabling simultaneous imaging and therapy. Special attention is given to the role of MNPs in immunogenic cell death induction and metastasis prevention, as well as novel concepts for circulating tumor cell capture. Despite promising results in vitro and in vivo, clinical translation remains limited by insufficient tumor accumulation after systemic delivery, safety concerns, and a lack of standardized treatment protocols. Future progress will require interdisciplinary innovations in nanomaterial engineering, active targeting technologies, and real-time treatment monitoring to fully integrate MH into multimodal cancer therapy and improve patient outcomes. Full article

This study provides a comparison between magnetic-to-thermal energy conversion efficiency in liquid and gel phases under high-frequency magnetic fields. Magnetite cores (11 ± 2 nm) were tested as water-based ferrofluids and as 5 wt% agar ferrogels, both with and without a biocompatible polydopamine (PDA) shell. A custom two-phase coil switched between rotating (RMF) and alternating (AMF) modes, enabling phase- and coating-dependent effects to be measured at identical field strengths and frequencies (100–300 kHz, 1–4 kA/m). Across all conditions, RMF generated 1.7–2.1 times more specific loss power (SLP) than AMF, and moving from the liquid to the gel phase reduced SLP by 5–8%, indicating that heating is controlled by Néel relaxation with negligible Brownian contribution. SLP rose with magnetic-field amplitude according to a power law, while hysteretic losses remained minimal. PDA improved colloidal stability and biocompatibility without harming the heating performance, lowering SLP by <17%. Within Brezovich limits, the system still exceeded therapeutic hyperthermia thresholds. Thus, in this iron-oxide/PDA system, neither medium viscosity nor the PDA shell’s non-magnetic mass significantly affects thermal energy output, an important finding for translating laboratory calorimetry data into reliable, application-oriented modelling for magnetic hyperthermia. Full article

Small interfering RNAs (siRNAs) are particularly attractive among the frontier drugs due to their high specificity of action, activity on disease-inducing genes, and small molecular weight, thus being one of the most studied agents for gene therapy. However, siRNAs are prone to fast enzymatic degradation in the bloodstream, as well as other limitations that challenge their clinical translation. Nanoparticle (NP) delivery of siRNA has been proposed as a potential solution, overcoming their intrinsic limitations. In this regard, the siRNA delivery by magnetic nanoparticles is of particular interest because, being susceptible to external magnetic fields, it may be guided remotely, maximizing transfection efficiency and minimizing side effects. In addition, magnetic NPs would also allow a theranostic combination of drug delivery, magnetic resonance imaging, and hyperthermia. In this work we have studied the uptake of a model therapeutic siRNA by iron-doped hydroxyapatite nanoparticles (FeHA NPs), which are known to have excellent biocompatibility and magnetic susceptibility. We discovered that FeHA NPs stabilized by citrate (Cit-FeHA NPs) uptake siRNA by adsorption quickly and with high efficiency (ca. 90%) without altering nanoparticles physicochemical properties or colloidal stability. SiRNA-loaded Cit-FeHA NPs are able to slowly release their payload, with a sustained release of 45 days without siRNA degradation. Our work is therefore the preliminary validation of the suitability of FeHA NPs for magnetically guided delivery of therapeutic siRNAs. Full article

The removal of iron deposits on shipwreck surfaces by mechanical cleaning is labour-intensive work. This study develops an in situ gel and peeling cleaning method, utilising a carboxymethyl chitosan/tannic acid (CMCS/TA) colloidal solution spray on the surface of ferruginous deposits, promoting their removal by adhesion, chelation, and electrostatic bonding processes. The investigation confirmed that the CMTA-2 sample exhibited a sprayable viscosity of 263 mPa/s, the largest single removal thickness of 1.01 mm, a significant reduction in the fe/s atomic ratio by 2.53 units, and enhanced the deposit removal homogeneity. The field testing of the Nanhai I cultural relic showed a 14.37% reduction in iron concentration and a significant decrease in red colour (Δa* = 4.36). The synergistic mechanism involves TA chelating Fe²⁺/Fe³⁺ ions, while the CMCS gel network facilitates interfacial adhesion and mechanical peeling, hence promoting efficient and controllable cleaning. Full article

The effect of pH and temperature on the interaction of sodium citrate-coated magnetic iron oxide nanoparticles (IONPs) with the BSA protein was studied using optical methods. The optical properties of aqueous colloids of BSA, IONPs, and BSA with IONPs were studied with pH changes in the range of 2–12 and temperature in the range of 25–85 °C. It was found that at pH 2.0, no significant changes in the optical properties were observed with increasing temperature in aqueous colloids containing a mixture of BSA with IONPs. Temperature affects the optical properties of BSA colloids with IONPs in the pH range from 5.0 to 8.0. Moreover, by increasing the temperature at these pH levels, it is possible to control the particle size in the colloids. In general, both temperature and pH have a significant effect on the properties of the aqueous colloid of BSA with IONPs and allow for the control of interactions between BSA and IONPs, namely, the processes of aggregation, particle reclustering, and protein denaturation. Full article

Superparamagnetic iron oxide nanoparticles (SPIONs) have gained significant attention for Magnetic Fluid Hyperthermia (MFH)-based cancer therapy. However, achieving high heating efficiency under a biologically safe Alternating Magnetic Field (AMF) remains a challenge. This study investigates the synthesis and optimization of SPIONs encapsulated in TPGS-stabilized PLGA nanoparticles (TPS-NPs) using a modified single emulsion solvent evaporation (M-SESE) method. The aim was to achieve efficient magnetic heating under biologically safe AMF conditions while maintaining biocompatibility and colloidal stability, making these magnetic nanoplatforms suitable for MFH-based cancer treatment. TPS-NPs were characterized using various techniques, including Dynamic Light Scattering (DLS), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), and Superconducting Quantum Interference Device (SQUID) magnetometry, to evaluate their hydrodynamic size (Dh), zeta potential (ζ), encapsulation efficiency, and superparamagnetic properties. Calorimetric MFH studies demonstrated superior heating efficiency, with Specific Absorption Rate (SAR) and Intrinsic Loss Power (ILP) values optimized at an AMF of 4.1 GAm⁻¹s⁻¹, remaining within Hergt’s biological safety limit (~5 GAm⁻¹s⁻¹). These findings suggest that SPION-encapsulated TPS-NPs exhibit enhanced heat induction, making them promising candidates for MFH-based cancer therapy. The study highlights their potential as multifunctional nanoplatforms for magnetic hyperthermia therapy, paving the way for clinical translation in oncology for advanced cancer treatment. Full article