Search Results (1,214)

Surface plasmon resonance (SPR) is a key tool for quantifying biomolecular interactions, and its use in studying interacting components outside cellular systems is well-established. Over the past 20–25 years, cell-based SPR techniques have emerged, with the promise of precise detection of molecular interactions within their normal physiological environment. Research on a wide variety of biological samples, which requires the detection of numerous parameters, has led to the development of a broad range of SPR techniques. This review aims to trace the chronological development of these techniques and the factors that have driven them. In this context, particular focus is given to grating-coupled SPR applied to cell assays. Its specific capabilities are examined, and the respective advantages and disadvantages of other SPR techniques are discussed based on the results obtained from studying specific biological objects. Finally, we venture to predict the promising SPR techniques, as well as the areas of application in which significant results can be expected. Full article

Antibiotic resistance and biofilm-associated infections require sustainable antimicrobial platforms that combine efficacy with biocompatibility. Fermented matrices are attractive for green nanomaterial production because they provide reducing metabolites and surface-active capping compounds. Rooibos kombucha is a polyphenol-rich fermentation system with potential to serve as a biosynthetic matrix for silver nanoparticles (AgNPs). The present work aimed to develop a rooibos kombucha-enabled platform for the green biosynthesis of phytochemical-capped silver nanoparticles, AgNPs-K, and evaluate their antibacterial, antibiofilm, and in vivo activity. Rooibos kombucha was fermented for 14 days and profiled by liquid chromatography–tandem mass spectrometry (LC–MS/MS). AgNPs-K were generated using kombucha extract and AgNO₃, purified, and characterized by ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and nanoparticle tracking analysis. Antibacterial activity against eight Gram-positive and Gram-negative reference pathogens was assessed by EUCAST-based microdilution and time-kill assays. Biofilm inhibition was measured by the crystal violet assay. In vivo toxicity and therapeutic efficacy were evaluated in Galleria mellonella larvae. AgNP formation was confirmed by a surface plasmon resonance (SPR) peak at 415 nm. TEM showed predominantly spherical nanoparticles with a main size range of 20–30 nm, a hydrodynamic diameter of 98 nm, and a zeta potential of −14.62 ± 0.04 mV. AgNPs-K showed overlapping minimum inhibitory concentration and minimum bactericidal concentration values of 1.14 µg/mL for Gram-positive species and 1.33 µg/mL for Gram-negative species. Time-kill assays showed rapid bactericidal activity after threshold concentrations were reached, with sustained suppression at 24 h. Biofilm formation was abolished at 40 µg/mL and strongly reduced at lower concentrations. AgNPs-K were non-toxic up to 400 µg/mL and improved survival in six of seven infection models. Fermented rooibos kombucha functions as an effective biosynthetic matrix for the green production of phytochemical-capped AgNPs. The resulting nanoparticles combine low-dose antibacterial and antibiofilm activity with favorable in vivo tolerability and efficacy, supporting fermentation-enabled nanobiotechnology strategies against biofilm-associated infection. Full article

Background/Objectives: Wound infections represent a major clinical challenge due to their polymicrobial nature, biofilm formation, and increasing antimicrobial resistance, which compromise conventional treatments. This study aimed to develop and evaluate ligand-stabilized silver nanoparticles (AgNPs) with improved antimicrobial activity and cytocompatibility, and to investigate their incorporation into electrospun nanofibers for wound management. Methods: Four AgNP formulations stabilized with citrate, cysteine, ketorolac, and diclofenac were synthesized via chemical reduction. Physicochemical characterization included surface plasmon resonance and zeta potential measurements. Antimicrobial activity was assessed through minimum inhibitory concentration (MIC) and bactericidal assays against Gram-positive, Gram-negative, and fungal strains. Toxicity was evaluated using the HET-CAM assay, while cytocompatibility was determined in fibroblasts, MG-63 cells, and mesenchymal stem cells. Diclofenac-stabilized AgNPs were incorporated into electrospun PCL/PEO nanofibers to generate a functional nanocomposite system. Results: All AgNPs exhibited a characteristic SPR at ~400 nm and high colloidal stability. Diclofenac-stabilized AgNPs (dc-AgNPs) showed the highest antimicrobial activity, with MIC values of 18.8 mg/L against Staphylococcus aureus and Pseudomonas aeruginosa, and 4.7 mg/L against Candida albicans, along with strong bactericidal effects. HET-CAM assays indicated negligible irritation at concentrations up to 75 mg/L. Cytocompatibility results revealed a dose-dependent response, with fibroblasts being more sensitive. Electrospun nanofibers loaded with dc-AgNPs achieved a 2.6 log reduction against Streptococcus mutans and moderate reductions (0.4–0.7 log) against other pathogens. Conclusions: Ligand engineering critically influences the antimicrobial efficacy and biocompatibility of AgNPs. The incorporation of dc-AgNPs into electrospun nanofibers represents a promising approach for treating biofilm-associated wound infections. Full article

This study proposes a novel anti-resonant fiber sensing structure based on a composite “egg-shaped” configuration with surface plasmon resonance (SPR) effect. By designing a novel anti-resonant structure consisting of a semicircle and a semi-ellipse and coating its inner surface with a gold film, the optimal structural parameters are determined through three sets of simulation experiments using temperature sensitivity as the criterion. The optimal sensing structure was applied to the simulated detection and analysis of cancer cells, aiming to provide value and reference for the application of high-sensitivity optical fiber sensor in the field of cancer cell detection. Simulation results show that the proposed sensing structure achieves a maximum temperature sensitivity (TS) of 3.86 nm/°C. For the detection of six different types of cancer cells, the maximum wavelength sensitivity (WS), optimal resolution (R), maximum figure of merit (FOM), maximum signal-to-noise ratio (SNR), and best limit of detection (LOD) reach 12,142.86 nm/RIU, 8.24 × 10⁻⁶, 3035.72 RIU⁻¹, 65.50, and 0.94 nm, respectively. Owing to its unique detection mechanism, the proposed sensing structure exhibits label-free characteristics and demonstrates balanced and excellent performance across all metrics for both temperature and cancer cell detection, showing broad application prospects and great potential in the fields of environmental monitoring and medical prevention and treatment. Full article

This study explored the influence of high silver (Ag) loading (5–10 mol%) on the photocatalytic performance of zirconium (Zr) co-doped TiO₂ (AZT) with a low Zr content. Although various Ag/Zr ratios have been reported, the effect of high Ag loading combined with low Zr content remains largely unrevealed, particularly in low-temperature synthesis where the role of Zr as a phase inhibitor is less critical. To address this gap, the AZT photocatalyst was fabricated via a solvothermal method combined with organic-free peroxy route. Characterization indicated Zr⁴⁺ incorporated into the TiO₂ lattice, inducing structural distortions and promoting Ti³⁺ defect states. Simultaneously, silver existed as ternary Ag species, which functioned as visible light responsive co-catalysts that enhanced light absorption via Surface Plasmon Resonance (SPR) and facilitated efficient charge separation. Photocatalytic performance was evaluated through Methylene Blue (MB) decolorization under household LED lamp. The optimized 7% Ag loaded catalyst achieved 99.4% removal efficiency within 6 h, with a reaction rate ten times higher than the Zr-doped sample. This superior activity was attributed to a p-n heterojunction and the SPR effect, narrowing the optical band gap to 2.60 eV. Radical scavenger experiments confirmed that the process was primarily driven by photogenerated holes. Full article

Background: Hydroxysafflor Yellow A (HSYA), the major bioactive component from Carthamus tinctorius L., exerts significant protective effects against myocardial ischemia-reperfusion injury (MIRI). Mitophagy is pivotal in the pathological process of MIRI, yet the specific molecular mechanism underlying HSYA-mediated mitophagy regulation remains unclear. Objective: This study aimed to investigate the association between HSYA treatment and mitochondrial autophagy in murine MIRI and to explore the potential mechanistic role of the SIRT1-FOXO3-BNIP3 signaling pathway using functional loss-of-function and rescue experiments. These findings may provide preliminary evidence supporting the clinical translational potential in MIRI therapy. Methods: Mouse myocardial ischemia-reperfusion injury (MIRI) model and oxygen-glucose deprivation/reoxygenation (OGD/R)-induced AC16 cardiomyocyte injury models were established. Metabolomics, molecular docking, and surface plasmon resonance (SPR) techniques were combined to screen the potential targets of HSYA. The SIRT1 inhibitor EX527 and SIRT1 siRNA were used to verify the underlying mechanism. Cardiac function, myocardial infarct size, mitochondrial function, the expression of autophagy-related proteins, and protein–protein interaction were detected and analyzed. Results: Compared with the MIRI group, HSYA significantly improved cardiac function in mice, as evidenced by increased left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) (p < 0.01), attenuated ST-segment elevation, and improved myocardial perfusion. HSYA also markedly reduced myocardial infarct size (p < 0.01) and serum levels of CK-MB, LDH, and cTnI (all p < 0.01) and ameliorated myocardial histopathological damage and mitochondrial ultrastructural integrity. Mechanistic studies revealed that HSYA significantly upregulated the expression of SIRT1, FOXO3, BNIP3, Beclin-1, and the LC3II/I ratio while downregulating p62 expression (p < 0.01), consistent with enhanced mitophagy-related activity. Furthermore, these protective effects were markedly attenuated upon SIRT1 inhibition or siRNA-mediated silencing, whereas HSYA intervention partially reversed these alterations. Additionally, co-immunoprecipitation (Co-IP) and pull-down assays demonstrated that HSYA promoted protein–protein interactions between SIRT1-FOXO3, FOXO3-BNIP3, and BNIP3-LC3B. Conclusions: These findings highlight that HSYA is associated with improved cardiac function, enhanced mitophagy-related activity, and upregulated SIRT1-FOXO3-BNIP3 signaling, providing robust experimental evidence for its clinical translational application in MIRI treatment. Full article

To meet the demand for highly sensitive temperature sensing in low-temperature environments, a surface plasmon resonance photonic crystal fiber (SPR-PCF) sensor with a central air hole and a dual-layer air-hole arrangement is designed and optimized. In this work, these air-hole features are used for mode-field regulation in a low-temperature sensing structure based on surface plasmon resonance (SPR), together with a polished gold film and an ethanol/chloroform (1:1) temperature-sensitive medium. The finite element method (FEM) was employed to analyze the resonance behavior and thermal response, and key structural parameters, including gold-film thickness, air-hole sizes, and radial positions, were optimized through cumulative parametric scanning. The optimized sensor shows good temperature response from −25 °C to 40 °C, with a maximum sensitivity of 36 nm/°C, a full width at half-maximum (FWHM) of 18.57 nm, and a figure of merit (FOM) of 1.2923. It is promising for cold-chain monitoring, low-temperature storage and transportation, and low-temperature sensing. Full article

Monolayer molybdenum disulfide (MoS₂) holds great promise for strain-tunable optoelectronic devices. The strain-dependent dielectric function is a core parameter to characterize the tunability of optoelectronic properties. However, due to the extremely short light–matter interaction path length for atomically thin materials, measurements are challenging. In this work, we measured the dielectric function of strained monolayer MoS₂ using the surface plasmon resonance (SPR) method with the simulated annealing particle swarm optimization (SAPSO) algorithm. When the applied strain ranged from −0.23% (compressive strain) to +0.20% (tensile strain), the dielectric function at seven characteristic wavelengths around the exciton absorption peaks was extracted. Our results demonstrate that both the real part (ε_2r) and the imaginary part (ε_2i) of the dielectric function evolved almost linearly with the applied strain from −0.23% to +0.20%. Based on these results, we further obtained the strain-induced variations in the refractive index (n) and the extinction coefficient (k). At exciton absorption peak B (600 nm), the strain-induced change rate for n reached a maximum of about −0.0141%⁻¹. At the rising edge of the B exciton absorption (580 nm), the strain-induced change rate for k reached a maximum of about −0.3261%⁻¹. This work presents a quantitative extraction of strain-dependent dielectric function of monolayer MoS₂ over excitonic band-edge wavelengths using phase SPR–SAPSO fitting. The proposed method can be extended to the measurement of other atomically thin materials. Full article

The study compares the effects of the HSP60-derived mutated peptide (CIGB-258) and its wild-type peptide (E18-3) on preventing carboxymethyllysine (CML)- and ethanol (Et-OH)-induced hemorrhagic events and acute toxicity in zebrafish. The results suggest a 67% survivability and swimming recovery in CIGB-258-treated zebrafish compared to only 20% in the CML+Et-OH-treated group. No effect of E18-3 was noticed on CML+Et-OH-impaired zebrafish survivability and swimming ability. Similarly, no effect of E18-3 was noticed on the CML+Et-OH-disturbed blood oxidative and antioxidant variables. In contrast, CIGB-258 showed a notable 35% lower rate of oxidized contents, and 2.0-fold and 1.2-fold higher paraoxonase (PON) and ferric ion reduction activity (FRA), respectively, than in the E18-3 group. Also, the CML+Et-OH-induced dyslipidemia was substantially prevented by the CIGB-258, whereas no protective effect of E18-3 was noticed. Similarly, the CML+Et-OH-triggered hepatic inflammation, steatosis, kidney damage, severe gastrointestinal bleeding, and intestinal fibrosis were successfully mitigated by co-treatment with CIGB-258. Surface plasmon resonance analysis revealed a substantial binding affinity of CIGB-258 for HDL₂ and HDL₃, characterized by association rate constants (K_a) of 14.78 and 6.20 μM⁻¹s⁻¹, dissociation rate constants (K_d) of 0.35 s⁻¹ and 0.22 s⁻¹, and equilibrium dissociation constants (K_D) of 0.024 and 0.035 μM, respectively. In conclusion, CIGB-258 exerted a substantial impact on CML+Et-OH-triggered adverse events, with high affinity for HDL, whereas E18-3 exposure remained unaffected and failed to produce any beneficial effects. Full article

Haemoglobin (Hb) concentration is a key biomarker for several diseases. Traditional laboratory methods often have limitations due to their time-consuming nature, the need for skilled personnel, or the use of high-cost instrumentation. This work presents a sensing strategy for developing new point-of-care tests (POCTs) for Hb detection via a proof of concept. The proposed sensing approach is implemented using plasmonic plastic optical fiber (POF) sensor chips that integrate an electropolymerized molecularly imprinted polymer (eMIP) film on the plasmonic surface for Hb-selective detection. The developed sensor system demonstrates an ultra-low detection limit of 80 fM in buffer, about five orders of magnitude lower than that of other comparable Hb sensors. Selectivity tests against common interfering proteins, such as bovine serum albumin (BSA) and immunoglobulin G (IgG), confirmed high specificity towards the target analyte. Moreover, the sensor’s performance was tested using a whole-blood sample, yielding results consistent with those of standard haematology analysis. The proposed sensor system, based on simple equipment, provides a quick (about 10 min) and cost-effective (about 10 euros per chip) label-free diagnostic tool for POCTs in real-world scenarios, such as finger-prick sampling, offering a less invasive alternative to traditional laboratory methods, towards devices useful for Internet of Medical Things (IoMT). Full article

Background: Renal aging represents a pivotal contributor to the pathogenesis and progression of age-related kidney disorders. D-Pinitol (DP), a bioactive cyclitol naturally present in food plants, exhibits multiple beneficial biological activities. Nevertheless, its role in counteracting renal aging remains unclear. Methods: This study employed both in vitro (HK-2 cells) and in vivo (C57BL/6J mice) models of D-galactose (DG)-induced renal aging. A panel of experimental approaches was applied to characterize the protective effects and molecular mechanisms of DP against renal aging, including Western blot, qPCR, ELISA, transcriptomic profiling, transmission electron microscopy, surface plasmon resonance (SPR), immunohistochemistry, and immunofluorescence staining. Results: DP significantly attenuated DG-induced renal aging-like changes in vitro and in vivo by preserving mitochondrial function and alleviating inflammatory responses. Transcriptomic analysis suggested SARM1 as a potential key target responsible for the beneficial effects of DP. In DG-induced aging models, SARM1 was remarkably upregulated in a tubule-specific pattern and acted as a critical mediator of mitochondrial dysfunction. Damaged mitochondria released mtDNA, which further activated the cGAS–STING innate immune signaling pathway, consequently promoting the senescence-associated secretory phenotype (SASP) and renal inflammation. Mechanistically, molecular docking and related assays suggested that DP may stabilize the auto-inhibitory conformation of SARM1, thereby potentially preventing its activation. Conclusions: DP attenuates DG-induced renal aging-like changes via suppressing the SARM1–cGAS–STING axis, thereby restoring mitochondrial homeostasis and mitigating inflammation. Given the lack of effective interventions targeting renal aging, these findings suggest SARM1 as a novel potential therapeutic target for renal aging and highlight DP as a promising food-derived anti-aging ingredient for renal protection. Full article

Recognized for its dual nutritional and therapeutic value, the fungus Hericium erinaceus is increasingly acknowledged as a rich resource of naturally derived α-glucosidase inhibitors. In this study, eight compounds were isolated from H. erinaceus, including three novel compounds designated as erinacerins X−Z (1, 2, and 6). Their absolute configurations were definitively elucidated using a combination of NMR, HR-MS, and ECD calculations. Furthermore, an integrated screening strategy combining molecular docking, molecular dynamics (MD) simulations, and surface plasmon resonance (SPR) analysis identified two isoindolin-1-ones (2 and 3) as potent naturally derived α-glucosidase inhibitors. Notably, in vitro testing established compounds 2 and 3 as robust α-glucosidase inhibitors, affording IC₅₀ values of 17.80 ± 1.03 μM and 19.50 ± 1.33 μM, respectively. MD simulations revealed that electrostatic interactions and van der Waals forces are the primary drivers of this intermolecular association. These findings were further corroborated by SPR analysis, which quantified their high-affinity binding kinetics to the enzyme. Overall, this combined approach establishes a solid foundation for the discovery and development of natural α-glucosidase inhibitors from H. erinaceus. Full article

The distinct electronic and optical properties of gold nanoparticles (NPs) have made them innovative assets for biomolecular sensing. This review outlines the various gold nanoparticle-based biosensing techniques centred on biomolecule detection and signal relay. We discussed the physical, chemical (Turkevich, Brust, seed-mediated growth, and digestive ripening) and biological syntheses involving bacteria, fungi, and plant extracts. Also discussed were the various ways these techniques affect the shape and functionality of the nanoparticles. Detection techniques are typically classified as the following: colourimetric, fluorescence-based, electrochemical, and surface plasmon resonance (SPR). Colourimetric assays enable visual detection of proteins and oligonucleotides by monitoring gold NP aggregation, while molecular beacons enable precise fluorescent-based detection. Quantitative detection of small molecules and gold NPs can be performed using electrochemical sensing, and biomolecular interactions can be analysed in real time using SPR. With the review focusing on the integration of gold NPs with microfluidics and wearable sensors, this synthesis aims to support the design of more practical, real-world applications of the described techniques. Full article

NS4A plays a role in forming the flavivirus replication complex, which inhibits apoptosis in host cells by inducing autophagy, thereby promoting viral replication. The host protein ENO1 interacts with NS4A, but the precise mechanism underlying this interaction and its role in viral replication remain unclear. In this study, we identified ZIKV NS4A^1–73 as a key regulator of replication and infection cycles in both temporal and spatial dimensions. Through surface plasmon resonance (SPR) analysis, we demonstrated that ENO1 directly interacts with NS4A^1–73. This critical binding inhibits the enzymatic activity of ENO1 and reduces cellular lactate and ATP production. Our findings suggest that ZIKV NS4A may effectively impede cellular metabolism by targeting the host factor ENO1, thus disrupting the glycolytic process. This insight could open new avenues for targeting ZIKV and similar viruses in therapeutic strategies. Full article

Biosensors have emerged as a rapidly evolving area of research, offering transformative potential across biomedical diagnostics, environmental monitoring, and pharmaceutical applications. Among the diverse range of biosensing technologies, graphene-based surface plasmonic resonance (SPR) biosensors have attracted particular interest due to their exceptional sensitivity, scalability for mass production, and cost-effective fabrication processes. This study explores the operational principles and current design methodologies of graphene-based SPR biosensors, with a special emphasis on the role of electrolyte gating and its impact on sensor performance. Furthermore, the influence of graphene’s quantum capacitance is investigated as a critical parameter for improving the accuracy and reliability of performance predictions in the proposed sensor configuration. Computational analysis of sensitivity and key performance metrics was conducted. Notably, key performance metrics of the sensor improved upon incorporating quantum capacitance effects into the simulation framework. At a β₂-microglobulin concentration of 0.00118 g/L, the sensitivity increased to 174 GHz·g/L, the figure of merit reached 0.55 L/g, the quality factor was 0.01, the signal-to-noise ratio (SNR) rose to 0.008, and the detection accuracy (DA) reached 0.08 L/THz, demonstrating the significant impact of quantum capacitance on the sensor’s performance. These findings highlight the potential of quantum-electrostatic considerations to enhance the precision and efficacy of graphene-based SPR biosensors, paving the way for the development of next-generation biosensing platforms with improved analytical capabilities. Unlike conventional graphene SPR biosensors, which primarily detect refractive index changes near the graphene surface, our model explicitly considers the electrostatic effect of biomolecules on graphene’s Fermi energy. By modelling β2-microglobulin as a charged species, we compute the resulting electric double layer and incorporate quantum capacitance in series. This amplifies the charge-induced modulation of graphene’s optical conductivity, and, combined with a graphene perfect absorber design, leads to enhanced plasmonic resonance shifts. Consequently, our approach achieves higher sensitivity and more precise detection of biomolecular interactions compared to traditional simulations. Full article