Search Results (347)

Magnetotactic bacteria (MTB), a unique group of Gram-negative prokaryotes, have the remarkable ability to biomineralize magnetic nanoparticles (MNPs) intracellularly, making them promising candidates for various biomedical applications such as biosensors, drug delivery, imaging contrast agents, and cancer-targeted therapies. To fully exploit the potential of MTB, a precise understanding of the structural, surface, and functional properties of these biologically produced nanoparticles is required. Given these concerns, this review provides a focused synthesis of the most widely used microscopic and spectroscopic methods applied in the characterization of MTB and their associated MNPs, covering the latest research from January 2022 to May 2025. Specifically, various optical microscopy techniques (e.g., transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM)) and spectroscopic approaches (e.g., localized surface plasmon resonance (LSPR), surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopy (XPS)) relevant to ultrasensitive MTB biosensor development are herein discussed and compared in term of their advantages and disadvantages. Overall, the novelty of this work lies in its clarity and structure, aiming to consolidate and simplify access to the most current and effective characterization techniques. Furthermore, several gaps in the characterization methods of MTB were identified, and new directions of methods that can be integrated into the study, analysis, and characterization of these bacteria are suggested in exhaustive manner. Finally, to the authors’ knowledge, this is the first comprehensive overview of characterization techniques that could serve as a practical resource for both younger and more experienced researchers seeking to optimize the use of MTB in the development of advanced biosensing systems and other biomedical tools. Full article

This work presents a novel and comprehensive framework for optimizing fiber optic evanescent wave (FOEW) localized surface plasmon resonance (LSPR) sensors by investigating the unique interaction between evanescent waves and plasmonic nanoparticles. Unlike propagating light, the evanescent wave is a localized, non-propagating field that interacts exclusively with absorbing media near the fiber surface. This characteristic highlights the importance of prioritizing nanoparticle absorption over total extinction in FOEW sensor design. The optical response of silver nanoparticles was modeled across a size range of 10–100 nm, showing that absorption increases with particle number. Among the sizes tested, 30 nm silver nanoparticles exhibited the highest absorption efficiency, which was confirmed experimentally. An analytical adsorption kinetics model based on diffusion transport further predicted that smaller nanoparticles yield higher surface coverage, a result validated through atomic force microscopy (AFM) and scanning electron microscopy (SEM) imaging. Refractive index (RI) sensitivity tests conducted on sensors fabricated with 10 nm, 20 nm, and 30 nm silver nanoparticles revealed that while smaller nanoparticles produced higher initial absorption due to greater surface density, the 30 nm particles ultimately provided superior RI sensitivity due to their enhanced absorption efficiency. These findings underscore the significance of absorption-centered nanoparticle design in maximizing FOEW LSPR sensor performance. Full article

A straightforward and economical engraving diode laser with a 455 $\pm$$5$ nm visible wavelength was employed for the first time in a pulsed laser fragmentation in liquid (PLFL) technique coupled simultaneously with a chemical reduction method to synthesize silver nanoparticles (AgNPs) in an Origanum majorana extract liquid, as a natural reduction agent. The chemical reduction correlated with the PLFL method to control the NP size by examining the effect of irradiation times. The AgNPs were characterized by X-Ray diffraction (XRD), UV–vis spectrophotometry, dynamic light scattering (DLS), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The lattice diffraction Bragg’s planes (111), (200), (220), (311), and (222) were found by XRD. The AgNPs had a surface plasmon resonance (SPR) peak at around 432–409 nm. The position of this SPR peak moves toward shorter wavelengths, by around 23 nm, with increased laser irradiation. When exposure times were increased, a drop in Ag NP size was revealed, from 22 nm when only a chemical reduction approach was used to 12 nm when the PLFL technique was associated. The DLS and TEM confirmed the UV–vis results. Such consideration suggests that combining the chemical reduction and PLFL methods could enable the tuning of the Ag NP size to be tailored for specific applications. This work could open the field for synthesizing NPs and controlling their size using an easy and handy engraving laser. Full article

Background: Breast cancer and chronic bacterial infections are pressing global health issues, and traditional treatments are often hampered by resistance and adverse side effects. This study sought to create silver nanoparticles (AgNPs) through eco-friendly synthesis using Hibiscus rosa sinensis (HRS) flower extract and to assess their antibacterial, antibiofilm, and anticancer properties. Methods: HRS extract functioned as both a reducing and stabilizing agent in the synthesis of AgNPs. The nanoparticles were characterized using ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). Antibacterial and antibiofilm properties were evaluated against gram-positive (Staphylococcus aureus and Enterococcus faecalis) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria using agar well diffusion and XTT reduction assays. The cytotoxic effects on MDMB-231 breast cancer cells and normal splenocytes were measured using the MTT assay, whereas fluorescence microscopy was used to observe reactive oxygen species (ROS) production, changes in mitochondrial membrane potential, and caspase-3 activation. Results: The synthesized HRS-AgNPs, primarily ranging from 10 to 50 nm, displayed a distinct surface plasmon resonance (SPR) peak at 428 nm. They exhibit notable antibacterial activity, especially against gram-positive bacteria, and effectively disrupt bacterial biofilms. Cytotoxicity evaluations showed that HRS-AgNPs decreased the viability of MDMB-231 cells in a dose-dependent manner, with minimal toxicity observed in normal splenocytes. The increase in ROS levels, reduction in mitochondrial membrane potential, and heightened caspase-3 activity collectively suggest apoptosis-driven cell death in cancer cells. Conclusions: HRS-AgNPs demonstrated dual functionality, with strong antibacterial and selective anticancer effects. Their environmentally friendly synthesis, stability, and significant biological activities suggest their potential for further development, including in vivo safety and efficacy assessments for clinical applications in treating infections and breast cancer. Full article

Clinical data as well as animal and cell studies indicate that certain antidiabetic drugs, including glucagon-like peptide 1 receptor agonists (GLP-1RAs), exert therapeutic effects in Alzheimer’s disease (AD) by modulating amyloid-β peptide (Aβ) metabolism. Meanwhile, the direct interactions between GLP-1RAs and Aβ and their functional consequences remain unexplored. In this study, the interactions between monomeric Aβ40/Aβ42 of GLP-1(7-37) and its several analogs (semaglutide (Sema), liraglutide (Lira), exenatide (Exen)) were studied using biolayer interferometry and surface plasmon resonance spectroscopy. The quaternary structure of GLP-1RAs was investigated using dynamic light scattering. The effects of GLP-1RAs on Aβ fibrillation were assessed using the thioflavin T assay and electron microscopy. The impact of GLP-1RAs on Aβ cytotoxicity was evaluated via the MTT assay. Monomeric Aβ40 and Aβ42 directly bind to GLP-1(7-37), Sema, Lira, and Exen, with the highest affinity for Lira (the lowest estimates of equilibrium dissociation constants were 42–60 nM). GLP-1RAs are prone to oligomerization, which may affect their binding to Aβ. GLP-1(7-37) and Exen inhibit Aβ40 fibrillation, whereas Sema promotes it. GLP-1 analogs decrease Aβ cytotoxicity toward SH-SY5Y cells, while GLP-1(7-37) enhances Aβ40 cytotoxicity without affecting the cytotoxic effect of Aβ42. Overall, GLP-1RAs interact with Aβ and differentially modulate its fibrillation and cytotoxicity, suggesting the need for further studies of our observed effects in vivo. Full article

Chinese herbal medicines have played a significant role in the development of new and effective drugs, but how to identify the active ingredients from complex extracts of traditional Chinese herbal medicines was a research difficulty. In recent years, few studies have focused on high-efficiency identification of small-molecule inhibitors of Programmed Death Ligand 1 with lower antigenicity and flexible structure tunability. In order to identify small molecule inhibitors of PD-L1 from complex Chinese herbal extracts, this study established a protein–ligand trapping system based on high-performance liquid chromatography coupled with a photo-diode array detector, ion trap/quadrupole time-of-flight tandem mass spectrometry, and a Programmed Death Ligand 1 affinity chromatography unit (ACPD-L1-HPLC-PDA-IT-TOF (Q-TOF)-MS) to rapidly screen and identify small-molecule inhibitors of Programmed Death Ligand 1 from Toddalia asiatica (L.) Lam. Fourteen components were then identified as PD-L1 binders, and surface plasmon resonance (SPR) validation results showed that six of them—magnoflorine (6), nitidine (22), chelerythrine (24), jatrorrhizine (13), toddaculin (68), and toddanol (45)—displayed PD-L1 binding activity. Laser scanning confocal microscopy results demonstrated that these compounds effectively inhibited the binding of PD-1 to PD-L1 in a dose-dependent manner. Additionally, flow cytometry analysis indicated they could promote human lung cancer cell line (A549) apoptosis when co-cultured with Peripheral Blood Mononuclear Cells (PBMCs). The system’s innovation lies in its first integration of dynamic protein–ligand trapping with multi-dimensional validation, coupled with high-throughput screening capacity for structurally diverse natural products. This workflow overcomes traditional phytochemical screening bottlenecks by preserving native protein conformations during affinity capture while maintaining chromatographic resolution, offering a transformative template for accelerating natural product-derived immunotherapeutics through the PD-1/PD-L1 pathway. Full article

In this study, silver nanoparticles (Ag NPs) were synthesized on the surface of rutile-phase titanium dioxide (R-TiO₂) using a plasma-assisted technique. Comprehensive analyses were conducted to investigate the structural, morphological, optical, and electrical properties of the synthesized nanocomposites. Transmission electron microscopy (TEM) images revealed the uniform decoration of Ag NPs (average size: 29.8 nm) on the R-TiO₂ surface. X-ray diffraction (XRD) confirmed the polycrystalline nature of the samples, with decreased diffraction peak intensity indicating reduced crystallinity due to Ag decoration. The Williamson–Hall analysis showed increased crystallite size and reduced tensile strain, suggesting grain growth and stress relief. Raman spectroscopy revealed quenching and broadening of R-TiO₂ vibrational modes, likely due to increased oxygen vacancies. X-ray photoelectron spectroscopy (XPS) confirmed successful plasma-assisted deposition and the coexistence of Ag⁰ and Ag⁺ states, enhancing surface reactivity. UV-Vis spectroscopy demonstrated enhanced light absorption across the spectral range, attributed to localized surface plasmon resonance (LSPR), and a reduced optical bandgap. Dielectric properties, including dielectric constants, loss factor, and AC conductivity, were evaluated across frequencies (4–8 MHz) and temperatures (20–240 °C). The AC conductivity results indicated correlated barrier hopping (CBH) and overlapping large polaron tunneling (OLPT) as the primary conduction mechanisms. Composition-dependent dielectric behavior was interpreted through the Coulomb blockade effect. These findings suggest the potential of plasma assisted Ag NP-decorated R-TiO₂ nanostructures for photocatalysis, sensor and specific electro electrochemical systems applications. Full article

This review explores advanced sensing technologies and deep learning (DL) methodologies for monitoring airborne particulate matter (PM), which is critical for environmental health assessments. It begins with discussing the significance of PM monitoring and introduces surface plasmon resonance (SPR) as a promising technique in environmental applications, alongside the role of DL neural networks in enhancing these technologies. This review analyzes advancements in airborne PM sensing technologies and the integration of DL methodologies for environmental monitoring. This review emphasizes the importance of PM monitoring for public health, environmental policy, and scientific research. Traditional PM sensing methods, including their principles, advantages, and limitations, are discussed, covering gravimetric techniques, continuous monitoring, optical and electrical methods, and microscopy. The integration of DL with PM sensing offers potential for enhancing monitoring accuracy, efficiency, and data interpretation. DL techniques, such as convolutional neural networks (CNNs), autoencoders, recurrent neural networks (RNNs), and their variants, are examined for applications like PM estimation from satellite data, air quality prediction, and sensor calibration. This review highlights the data acquisition and quality challenges in developing effective DL models for air quality monitoring. Techniques for handling large and noisy datasets are explored, emphasizing the importance of data quality for model performance, generalizability, and interpretability. The emergence of low-cost sensor technologies and hybrid systems for PM monitoring is discussed, acknowledging their promise while recognizing the need for addressing data quality, standardization, and integration issues. This review identifies areas for future research, including the development of robust DL models, advanced data fusion techniques, applications of deep reinforcement learning, and considerations of ethical implications. Full article

Background: Gold nanoparticles enhance immunity, promotes antigen uptake by antigen-presenting cells (APCs), and boost the response against tumor antigens; therefore, they are a promising delivery vehicle. Tumor lysates have shown favorable responses as inductors of anti-cancer immunity, but the effectiveness of these treatments could be improved. Hybrid nanosystems gold nanoparticles with biomolecules have been show promising alternative on uptake, activation and response on immune system. Objectives: This study’s objective was to develop a method of synthesizing gold nanoparticles employing a triple-negative breast cancer (4T1) cell lysate (AuLtNps) as a reducing agent to increase immunogenicity against breast cancer cells. Methods: Nanoparticle formation, size, and $\zeta$ potential were confirmed by surface plasmon resonance, dynamic light scattering, and transmission electron microscopy. Protein concentration was quantified using a Pierce BCA assay. The cytotoxic effects of treatments on murine macrophages were assessed, along with nanoparticle and tumor lysate uptake via epifluorescence microscopy. Using a murine model, cytokine secretion profiles were determined, and the efficacy in inhibiting the implantation of a 4T1 model was evaluated. Results/Conclusions: AuLtNps exhibited higher protein content than tumor lysate alone, leading to increased uptake and phagocytosis in murine macrophages, as confirmed by epifluorescence microscopy. Cytokine secretion analysis showed a proinflammatory response, with increased CD8+ and CD22+ lymphocytes and upregulation of APC markers (CD14, CD80, CD86, and MHC II+). Splenocytes demonstrated specific lysis of up to 40% against 4T1 tumor cells. In a murine model, AuLtNPs effectively inhibited tumor implantation, achieving an improved 90-days survival rate, highlighting their potential as an immunotherapy for triple-negative breast cancer. Full article

Recent advances in the clinical extracellular vesicles (EVs) field highlight their potential as biomarkers for diverse diseases and therapeutic applications. This study provides an in-depth characterization of 10k EVs from human microvascular endothelial cells (HMEC-1) exposed to benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon found in food and smoke. Given EVs’ complexity, with numerous surface and cargo proteins, phenotyping remains challenging. Here, we introduce a multiplex biosensor, in µarray format, for profiling EVs from distinct cellular conditions, employing a multimodal approach that combines surface plasmon resonance imaging (SPRi) and in situ atomic force microscopy (AFM) to decipher EVs’ biochemical and biophysical properties. SPRi experiments showed notable EV capture differences on ligands such as Anti-CD36, Anti-CD81, and Anti-ApoA between treated and control conditions, likely due to B[a]P exposure. A complementary AFM study and statistical analyses revealed size differences between EVs from treated and control samples, with ligands like Annexin-V, Anti-CD36, and Anti-VEGFR1 emerging as ligands specific to potential cytotoxicity biomarkers. Our findings suggest that B[a]P exposure may increase EV size and alter marker expression, indicating phenotypic shifts in EVs under cytotoxic stress. The original combination of SPRi and AFM reveals valuable data on the phenotypical and morphological heterogeneities of EV subsets linked to cytotoxic stresses and highlights the potential of EVs as specific toxicological markers. Full article

Ultraviolet (UV) photodetectors play a crucial role in various applications, ranging from environmental monitoring to biomedical diagnostics. This paper presents the fabrication and characterization of a high-performance UV photodetector using hexagonal boron nitride (hBN) decorated with gold nanoparticles (AuNPs). The hBN flakes were mechanically exfoliated onto SiO₂ substrates, and AuNPs were formed via thermal evaporation, resulting in the creation of a plasmonically active surface that enhanced light absorption and carrier dynamics. Raman spectroscopy, transmission electron microscopy, and electrical measurements were performed to comprehensively analyze the device structure and performance. The photodetector exhibited significantly improved photocurrent and responsivity under UV-B (306 nm) and UV-C (254 nm) illumination, with the responsivity reaching an increase of nearly two orders of magnitude compared to that of the pristine hBN device. These improvements are attributed to the synergistic effects of the wide bandgap of hBN and the localized surface plasmon resonance of the AuNPs. These findings demonstrate the potential of AuNP-decorated hBN for advanced UV photodetection applications and provide a pathway toward more efficient and miniaturized optoelectronic devices. Full article

Background/Objectives: Glioblastomas are the most common brain malignancies. Despite the implementation of multimodal therapy, patient life expectancy after diagnosis is barely 12 to 18 months. Glioblastomas are highly heterogeneous at the genetic and epigenetic level and comprise multiple different cell subpopulations. Therefore, small molecules such as nanobodies, able to target membrane proteins specific to glioblastoma cells or specific cell types within the tumor are being investigated as novel tools to treat glioblastomas. Methods: Here, we describe the identification of such a nanobody and its in silico and in vitro validation. NB3F18, as we named it, is directed against the membrane-associated protein FREM2, overexpressed in glioblastoma stem cells. Results: Three dimensional in silico modeling indicated that NB3F18 and FREM2 form a stable complex. Surface plasmon resonance confirmed their interaction with moderate affinity. As we demonstrated by flow cytometry, NB3F18 binds to glioblastoma stem cells to a greater extent than to differentiated glioblastoma cells and astrocytes. Immunocytochemistry revealed surface localization of NB3F18 on glioblastoma stem cells, whereas cytoplasmic localization of NB3F18 was observed in other cell lines. NB3F18 was detected by transmission electron microscopy on the plasma membrane and in various compartments of the endocytic pathway, from endocytic vesicles to multivesicular bodies (endosomes) and lysosomes. Interestingly, NB3F18 was cytotoxic to glioblastoma stem cells. Conclusions: Collectively, NB3F18 has been qualified as an interesting tool to target glioblastoma cells and as a potential vehicle to deliver biological or pharmaceutical agents to these cells. Full article

Metal–organic frameworks (MOFs) have emerged as versatile materials with remarkably high surface areas and tunable properties, attracting significant attention for various applications. In this work, the modification of a UiO-66 MOF with metal nanoparticles (NPs) is investigated for the purpose of enhancing its photocatalytic activity for CO₂ reduction to liquid fuels. Several NPs (Au, Cu, Ag, Pd, Pt, and Ni) were loaded into the UiO-66 framework and employed as photocatalysts. The synergistic effects of plasmonic resonance and MOF characteristics were investigated to improve photocatalytic performance. The synthesized materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), confirming the successful integration of metal NPs onto the UiO-66 framework. Morphological analysis revealed distinct distributions and sizes of NPs on the UiO-66 surface for different metals. Photocatalytic CO₂ reduction experiments demonstrated enhanced activity of plasmonic MOFs, yielding methanol and ethanol. The findings revealed by this study provide valuable insights into tailoring MOFs for improved photocatalytic applications through the incorporation of plasmonic metal nanoparticles. Full article

Plastic pollution, particularly from microplastics (MPs) and nanoplastics (NPs), has become a critical environmental and health concern due to their widespread distribution, persistence, and potential toxicity. MPs and NPs originate from primary sources, such as cosmetic microspheres or synthetic fibers, and secondary fragmentation of larger plastics through environmental degradation. These particles, typically less than 5 mm, are found globally, from deep seabeds to human tissues, and are known to adsorb and release harmful pollutants, exacerbating ecological and health risks. Effective detection and quantification of MPs and NPs are essential for understanding and mitigating their impacts. Current analytical methods include physical and chemical techniques. Physical methods, such as optical and electron microscopy, provide morphological details but often lack specificity and are time-intensive. Chemical analyses, such as Fourier transform infrared (FTIR) and Raman spectroscopy, offer molecular specificity but face challenges with smaller particle sizes and complex matrices. Thermal analytical methods, including pyrolysis gas chromatography–mass spectrometry (Py-GC-MS), provide compositional insights but are destructive and limited in morphological analysis. Emerging (bio)sensing technologies show promise in addressing these challenges. Electrochemical biosensors offer cost-effective, portable, and sensitive platforms, leveraging principles such as voltammetry and impedance to detect MPs and their adsorbed pollutants. Plasmonic techniques, including surface plasmon resonance (SPR) and surface-enhanced Raman spectroscopy (SERS), provide high sensitivity and specificity through nanostructure-enhanced detection. Fluorescent biosensors utilizing microbial or enzymatic elements enable the real-time monitoring of plastic degradation products, such as terephthalic acid from polyethylene terephthalate (PET). Advancements in these innovative approaches pave the way for more accurate, scalable, and environmentally compatible detection solutions, contributing to improved monitoring and remediation strategies. This review highlights the potential of biosensors as advanced analytical methods, including a section on prospects that address the challenges that could lead to significant advancements in environmental monitoring, highlighting the necessity of testing the new sensing developments under real conditions (composition/matrix of the samples), which are often overlooked, as well as the study of peptides as a novel recognition element in microplastic sensing. Full article

The aim of this study was to investigate the inhibitory effect of nintedanib (BIBF) on glioblastoma (GBM) cells and its mechanism of action and to optimize a drug delivery strategy to overcome the limitations posed by the blood–brain barrier (BBB). We analyzed the inhibition of GBM cell lines following BIBF treatment and explored its effect on the autophagy pathway. The cytotoxicity of BIBF was assessed using the CCK-8 assay, and further techniques such as transmission electron microscopy, Western blotting (WB), and flow cytometry were employed to demonstrate that BIBF could block the autophagic pathway by inhibiting the fusion of autophagosomes and lysosomes, ultimately limiting the proliferation of GBM cells. Molecular docking and surface plasmon resonance (SPR) experiments indicated that BIBF specifically binds to the autophagy-associated protein VPS18, interfering with its function and inhibiting the normal progression of autophagy. However, the application of BIBF in GBM therapy is limited due to restricted drug penetration across the BBB. Therefore, this study utilized poly-lactic-co-glycolic acid (PLGA) nanocarriers as a drug delivery system to significantly enhance the delivery efficiency of BIBF in vivo. In vitro cellular experiments and in vivo animal model validation demonstrated that PLGA-BIBF NPs effectively overcame the limitations of the BBB, significantly enhanced the antitumor activity of BIBF, and improved therapeutic efficacy in a GBM BALB/c-Nude model. This study demonstrated that BIBF exerted significant inhibitory effects on GBM cells by binding to VPS18 and inhibiting the autophagy pathway. Combined with the PLGA nanocarrier delivery system, the blood–brain barrier permeability and anti-tumor effect of BIBF were significantly enhanced. Targeting the BIBF-VPS18 pathway and optimizing drug delivery through nanotechnology may represent a new strategy for GBM treatment, providing innovative clinical treatment ideas and a theoretical basis for patients with GBM. Full article