Search Results (247)

This study presents a statistically optimized protocol for the green synthesis of gold nanoparticles (Au NPs) using aqueous Kalanchoe pinnata leaf extract (AKPLE). An integrated experimental strategy, transitioning from preliminary one-factor-at-a-time (OFAT) screening to a five-factor Box–Behnken Design, was employed to model and simultaneously optimize two critical optical responses derived from surface plasmon resonance: the peak position (λ_max) and its absorbance intensity. Highly predictive quadratic models (R² > 0.97) revealed that synthesis outcomes are governed by significant nonlinear curvature, with minimal interaction effects. Multi-response optimization via a desirability function identified a harmonized set of conditions (HAuCl₄: 0.44 mM, AKPLE: 3.50% v/v, temperature: 80.6 °C, pH: 7.2, time: 66.7 min) predicted to minimize λ_max at 540 nm while maximizing absorbance to 0.61. Synthesis under these optimized conditions successfully produced spherical, crystalline Au NPs, as confirmed by characterization (average TEM size: 26.3 ± 4.1 nm; zeta potential: –30.45 mV). This work demonstrates that a hybrid OFAT-RSM approach is superior for the precise, multivariate optimization of plant-mediated Au NP synthesis, providing a validated and scalable framework to balance nanoparticle size and plasmonic intensity—an outcome unattainable through conventional OFAT methods. Full article

Wounds, particularly chronic wounds, represent an increasing challenge for global health systems, affecting millions of people worldwide, and are often associated with persistent infections, biofilms, and multidrug-resistant microorganisms (MDRMs). In this context, the search for effective therapeutic alternatives has driven interest in photodynamic therapy (PDT), an approach in which light-excited photosensitizers promote the generation of reactive oxygen species (ROS) with antimicrobial and wound healing properties. Although first- and second-generation organic photosensitizers are widely used, they have significant limitations, including low aqueous solubility, self-aggregation, reduced photostability, and unsatisfactory ROS quantum yields. To overcome these drawbacks, various nanotechnology-based strategies have been explored. Among them, metallic nanoparticles stand out because they serve as carriers and exhibit intrinsic photosensitizing activity, high resistance to photobleaching, and remarkable extinction coefficients, which favor efficient singlet oxygen generation. Furthermore, metals such as gold and silver can enhance the performance of organic photosensitizers through a process known as metal-enhanced singlet oxygen generation, whereas others, such as copper, zinc, manganese, and magnesium, actively participate in biochemical events associated with the inflammatory and regenerative phases of wound healing. Considering these advances, this review compiles evidence published over the past five years regarding the use of metallic or metal-containing nanoparticles in PDT for acute and chronic wounds, with an emphasis on in vivo studies. In addition, we discuss the epidemiological and pathophysiological aspects of wounds and the intrinsic wound healing and antimicrobial properties of metallic compounds, thereby providing an integrated and up-to-date perspective. Full article

Gold nanoparticles (AuNPs) were synthesized via two complementary routes, an inorganic surfactant-mediated method and a plant-extract-assisted biosynthesis, to elucidate how synthesis pathways influence nanoparticle physicochemical properties. In the inorganic route, hexadecyltrimethylammonium bromide (CTAB)-stabilized AuNPs were prepared using CTAB dissolution temperatures of 70–90 °C. UV–Vis spectroscopy showed localized surface plasmon resonance (LSPR) bands at 554–556 nm, while dynamic light scattering (DLS) indicated a decrease in hydrodynamic diameter from 110 to 97 nm with increasing dissolution temperature. Zeta potentials above +40 mV indicated strong electrostatic stabilization, and transmission electron microscopy (TEM) revealed ultrasmall Au cores with a narrow size distribution (2.4–3.0 nm) and a face-centered cubic crystal structure. In the biosynthetic route, AuNPs were obtained using aqueous Erythroxylum coca leaf extracts (1–4% w/v). The extracts exhibited a concentration-dependent red shift (~380 to ~420 nm), and biosynthesized AuNPs displayed LSPR bands in the 550–580 nm range. DLS yielded hydrodynamic diameters of 270–390 nm, with pronounced aggregation (3341 nm) at the lowest extract concentration. Under optimized conditions (HC5, n = 5), reproducible plasmonic and colloidal properties were obtained (maximum absorbance, localized surface plasmon resonance wavelength (λ_max) = 569.6 ± 1.7 nm; hydrodynamic diameter (D_H) = 237.6 ± 24.3 nm; absolute zeta potential (|ζ|)= 32.2 ± 2.6 mV). TEM analysis indicated predominantly quasi-spherical particles with a broader, log-normal size distribution, consistent with extract-mediated growth under heterogeneous organic capping environments. Full article

The development of anisotropic gold nanostructures supporting localized surface plasmon (LSP) resonances in the near-infrared (NIR) biological window is of great interest for diagnostic and therapeutic nanotechnologies. Here, we report gold open-shell nanoparticles (AuOSNs), a symmetry-broken nanoshell architecture exhibiting strong NIR surface-enhanced Raman scattering (SERS) activity. AuOSNs were fabricated via a surfactant-free strategy combining bottom-up silica sphere assembly with a simple top-down gold deposition process, without using highly cytotoxic surfactants such as cetyltrimethylammonium bromide (CTAB). Boundary element method (BEM) simulations revealed that the asymmetric open-shell geometry induces NIR LSP resonances with pronounced electromagnetic field localization near the opening edges, depending on excitation configuration. Consistent with these predictions, extinction spectra of AuOSNs dispersed in water showed an LSP resonance peak at ~793 nm, close to the 785 nm excitation wavelength for SERS. In aqueous dispersion, AuOSNs modified with 4-mercaptobenzoic acid (4-MBA) exhibited strong SERS activity with enhancement factors of ~10⁶. Furthermore, polyethylene glycol (PEG)-modified MBA/AuOSNs showed negligible cytotoxicity in vitro. SERS imaging confirmed that PEG/MBA/AuOSNs enable visualization of HeLa cells via characteristic MBA SERS signals. These results demonstrate that surfactant-free AuOSNs provide a biocompatible platform for NIR-excited SERS sensing and cellular imaging, highlighting their potential in plasmonic bioimaging applications. Full article

This study focuses on fabrication and comprehensive characterization of gold nanoparticles (AuNPs) stabilized with polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), correlating polymer degradation with colloidal stability and localized surface plasmon resonance (LSPR) behavior under controlled gamma doses from 5 to 125 Gy. AuNPs were synthesized via laser-assisted synthesis (LAS) in aqueous medium containing PVP or PEG as a stabilizing and capping agent. Morphology, size distribution, and surface functionalization of the resulting AuNPs@polymer-stabilized were verified through UV-Vis spectroscopy, FTIR, XRD, DLS, zeta potential, and TEM. Results show that the polymer shell effectively preserved the nanoparticles’ integrity by minimizing aggregation and maintaining LSPR features even after exposure to high gamma doses (>75 Gy). PVP demonstrated superior protection compared to PEG, due to the robustness of the solvation layer and carbonyl groups of PVP coating around the AuNPs. These findings highlight the potential of polymer-stabilized AuNPS for applications in radiation-rich environments, while demonstrating LAS as an environmentally friendly and efficient synthesis route. Full article

Skin cancer (SC) is the most prevalent malignancy worldwide, with subtypes varying in aggressiveness: basal cell carcinoma tends to be locally invasive, squamous cell carcinoma has a higher metastatic risk, and melanoma remains the deadliest form. Current treatments such as surgery, radiotherapy, and systemic chemotherapy are associated with aesthetic and functional morbidity, recurrence, and/or systemic toxicity. Although targeted therapies and immunotherapies offer clinical benefits, their high cost and limited accessibility underscore the need for innovative, affordable alternatives. Metal-based compounds (metallopharmaceuticals) are promising anticancer agents due to their ability to induce oxidative stress, modulate redox pathways, and interact with DNA. However, clinical translation has been limited by poor aqueous solubility, rapid degradation, and low skin permeability. This review discusses the most recent preclinical findings on gold, silver, platinum, palladium, ruthenium, vanadium, and copper complexes, mainly in topical and systemic treatments of SC. Advances in chemical and physical enhancers, such as hydrogels and microneedles, and in drug delivery systems, including bacterial nanocellulose membranes and nanoparticles, as well as liposomes and micelles, for enhancing skin permeation and protecting the integrity of metal complexes are also discussed. Additionally, we examine the contribution of photodynamic therapy to SC treatment and the use of mathematical and computational modeling to simulate skin drug transport, predict biodistribution, and support rational nanocarrier design. Altogether, these strategies aim to bridge the gap between physicochemical innovation and clinical applicability, paving the way for more selective, stable, and cost-effective SC treatments. Full article

Surface plasmon resonance (SPR) sensors based on photonic crystal fibers (PCFs) hold significant promise for high-precision detection in biochemical and chemical sensing. However, achieving high sensitivity in low-refractive-index (RI) aqueous environments remains a formidable challenge due to weak light-matter interactions. To address this limitation, this paper designs and proposes a novel dual-channel D-shaped PCF-SPR sensor tailored for the refractive index range of 1.34–1.40. The sensor incorporates a dual-layer gold/titanium dioxide film, with gold nanoparticles deposited on the surface to synergistically enhance both propagating and localized surface plasmon resonance effects. Furthermore, a D-shaped polished structure integrated with double-sided microfluidic channels is employed to significantly strengthen the interaction between the guided-mode electric field and the analyte. Finite element method simulations demonstrate that the proposed sensor achieves an average wavelength sensitivity of 5733 nm/RIU and a peak sensitivity of 15,500 nm/RIU at a refractive index of 1.40. Notably, the introduction of gold nanoparticles contributes to an approximately 1.47-fold sensitivity enhancement over conventional structures. This work validates the efficacy of hybrid plasmonic nanostructures and optimized waveguide design in advancing RI sensing performance. Full article

This work used activated carbon material obtained by chemical activation of abundantly available agricultural sunflower waste residues to remove metol (4-(methylamino) phenol sulfate, MTL) from aqueous solutions. The adsorbent structure was characterized using SEM-EDS and FT-IR spectroscopy. A modified screen-printed carbon electrode (SPCE) with gold nanoparticles synthesized using the Laser Ablation Synthesis in Solution (LASIS) method was used to detect MTL. The successful LASIS formation of gold nanoparticles was confirmed by the specific dark burgundy–red color. TEM measurements showed uniform pseudo-spherical particles with an average diameter of 7.9 ± 0.2 nm. The modified electrode showed improved electrochemical activity, which was confirmed by comparing it with an unmodified electrode using cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode was subsequently used to optimize the MTL detection conditions. UV–Vis spectroscopy was used to optimize the adsorption conditions, with the optimal values for pH and contact time found to be 8 and 120 min, respectively. The electrochemical detection of MTL was performed using differential pulse voltammetry, and the linear calibration range was established for concentrations ranging from 0.73–49.35 µM. The obtained limits of detection (LOD) and quantification (LOQ) were 0.06 µM and 0.2 µM, respectively. The efficiency of MTL removal was 100% after a contact time of 1 min and remained at 100% after 120 min. Full article

This study investigates the feasibility of adding gold nanoparticles (Au-NPs) to vanadium oxide (V₂O_x) serving the hole transport layer (HTL) material oin polymer solar cells to enhance cell performance. The first part of this study used Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a baseline and optimized the parameters of this HTL material. Then, the V₂O_x was substituted as the HTL material, and its parameters were optimized again. The second part involved incorporating an aqueous solution of gold nanoparticles (Au-NPs) with an average particle size of approximately 80 nm into V₂O_x. Due to the excitation of localized surface plasmon resonance (LSPR) by Au-NPs, the addition of Au-NPs to the V₂O_x layer can enhance the absorption efficiency of the P3HT:PCBM blended film. Therefore, compared with V₂O_x alone, the solar cells with Au-NPs incorporated into the V₂O₅ hole transport layer demonstrate improved power conversion efficiency (PCE). Full article

Multifunctional nanomaterials have been extensively investigated in theranostics to enhance therapeutic specificity, biocompatibility, and responsiveness to external magnetic gradients. We synthesized magnetoplasmonic nanocomposites comprising magnetite nanoparticles modified with gold and silver. Magnetite was synthesized via chemical co-precipitation and stabilized in an aqueous medium using glucose, which also served as a reducing agent for Au³⁺ and Ag⁺ ions on the nanoparticle surface. Microstructural, magnetic, spectral, and optical characterizations confirmed the successful formation of nanocomposites with properties suitable for biomedical applications. Plasmonic behavior was evidenced by visible-range absorbance maxima at 398 nm (Ag) and 538 nm (Au), while Transmission Electron Microscopy (TEM) revealed mean diameters of 21 and 23 nm. Zeta potential values of +23 mV for magnetite–silver and −40 mV for magnetite–gold nanocomposite samples indicated good suspension stability. Antibacterial activity against Gram-positive and Gram-negative bacteria was evaluated using agar diffusion and by determining the minimum inhibitory (MIC) and bactericidal (MBC) concentrations. Silver-modified magnetite nanocomposites exhibited the most potent effects, with MIC values of 0.01 mg/mL for Escherichia coli (E. coli) and 0.02 mg/mL for Staphylococcus aureus (S. aureus), and corresponding MBC values of 0.027 mg/mL and 0.055 mg/mL, respectively. These magnetoplasmonic nanostructures have significant potential for overcoming antibiotic resistance and enabling targeted therapeutic action through magnetic guidance. Full article

The rapid spread of the invasive brown macroalga Rugulopteryx okamurae has caused severe ecological and economic damage along the European coasts. Efforts to mitigate its impact have been largely ineffective, highlighting the need for alternative strategies to valorise this invasive species. This study explores the use of R. okamurae aqueous extract (RO extract) as a natural reducing and stabilizing agent for the green synthesis of gold (Au@RO), silver (Ag@RO), and platinum (Pt@RO) nanoparticles. The synthesized nanoparticles were extensively characterized using ultraviolet–visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), X-ray diffraction (XRD), zeta potential analysis, and Fourier-transform infrared spectroscopy (FTIR). The results confirmed the successful formation of spherical and stable nanoparticles. Furthermore, the antioxidant activity of the RO extract was determined before and after the synthesis of the nanoparticles by the determination of the reducing power, total phenolic content and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity. Notably, Pt@RO showed the highest enhancement in antioxidant activity among the nanoparticles synthesized. The findings demonstrate that R. okamurae can be repurposed as a valuable bioresource for the environmentally friendly production of metal nanoparticles with promising applications. Full article

Harnessing nature’s chemistry, this study explores the enhanced biomedical potential of Terminalia ferdinandiana Exell (Kakadu Plum) by transforming its aqueous leaf and fruit extracts into bio-inspired gold nanoparticles (AuNPs). The synthesis process was optimized by varying the Au³⁺/extract ratio and pH, with nanoparticle formation verified through UV–visible spectrophotometry, TEM, and DLS analyzes. Kakadu Leaf extract–conjugated AuNPs (AuKLs), synthesized at pH 8 with a 1:25 Au³⁺/extract ratio, produced the smallest and most uniform particles (21.1 nm; PDI 0.17). In contrast, fruit extract alone failed to generate stable nanoparticles, highlighting the pivotal role of leaf phytochemicals as natural reducing and stabilizing agents. Biological evaluations revealed that both the crude leaf extract and AuKLs possessed strong antioxidant capacity, while the AuKLs further exhibited selective anticancer activity effectively inhibiting breast cancer (MCF-7) and human cervical carcinoma (HeLa) cell proliferation without harming normal mammalian breast (MCF10A) cells. A combined 2:1 leaf-to-fruit extract formulation yielded well-stabilized AuNPs (AuKPLs) with biomedical properties comparable to AuKLs, though the fruit extract alone contributed minimally to both nanoparticle formation and biological performance. Overall, this study demonstrates that the phytochemical richness of T. ferdinandiana leaves enables the green synthesis of small, stable, and bioactive gold nanoparticles. The resulting nanoconjugates, AuKLs and AuKPLs, hold considerable promise for future pharmacological and therapeutic applications, bridging traditional plant-based medicine with modern nanotechnology. Full article

Aqueous semolina suspensions were reacted with spherical gold nanoparticles (AuNPs, nominal diameter, 20 nm) to assess the accessibility of cysteine thiols in durum wheat proteins, focusing on network-forming gluten proteins. Unlike small thiol reagents, covalent bond formation between gold ions on the AuNPs surface and protein thiols was greatly facilitated by the addition of 1% sodium dodecyl sulfate (SDS). SDS weakens non-covalent hydrophobic interactions within and among proteins, increasing the exposure of buried thiols without altering disulfide bonds. MS/MS analysis of proteolytic fragments from the isolated AuNP-protein covalent complexes allowed identification of the bound proteins. Proteomics data suggests that AuNPs also associate with gluten proteins lacking free thiols in their native structure, which are bound to AuNPs by forming disulfide bonds with other gluten proteins containing accessible thiols, via thiol-disulfide exchange reactions. This implies that thiol-disulfide reshuffling among gluten proteins occurs already in the grain, enabling proteins without free thiols to become part of AuNP-bound assemblies and revealing specific protein species involved in these early interactions. These observations highlight the role of thiol–disulfide exchange within the grain matrix, elucidating how such molecular rearrangements influence the topology and strength of protein networks in food and in related biopolymeric systems. Results of this exploratory study are discussed for their molecular relevance and for the potential use of size-based analytical and structural approaches in other biological contexts. Full article

Gold–silver nanoshells (GS-NSs) are hollow spherical nanoparticles with an alloyed Ag-Au shell. GS-NSs exhibit a tunable localized surface plasmon resonance (LSPR) in the visible to near-IR wavelengths as a function of composition and shell thickness and offer greater stability across pH ranges compared to other metal nanoparticles. These properties make GS-NSs promising materials for diagnostics, photothermal therapy, and photocatalysis. However, current research has explored GS-NSs only in aqueous systems, since they immediately aggregate in other solvents, limiting their utility. This paper provides an in-depth study of the choice and effect of non-thiol ligands on the stability and phase-transfer of GS-NSs from aqueous to non-aqueous solvents, such as ethylene glycol, tetrahydrofuran, dichloromethane, and toluene. Ligand exchange for functionalization of GS-NSs was performed with Triton X-100 (TX100), sodium stearate (NaSt), polyvinylpyrrolidone (PVP), and hydroxypropyl cellulose (HPC), prior to phase-transfer. The nanoparticles were phase-transferred to the non-aqueous solvents, and the stability of the colloids in the various solvents before and after functionalization was recorded with UV–visible spectroscopy, dynamic light scattering (DLS), zeta potential (ζ), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The study was also extended to include silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) to evaluate broad-range applicability. Among the ligands studied, HPC functionalization demonstrated the widest range of phase-transfer stability across 21 days for all three particle systems studied. UV–vis spectroscopy demonstrated sustained LSPR integrity after HPC functionalization in EG, THF, and DCM. SEM, TEM, and hydrodynamic size measurements by DLS further confirmed no aggregation in EG, THF, and DCM but suggested possible twinning or clustering in the solution. Overall, this work successfully identified non-toxic alternatives to expand the LSPR stability of citrate-synthesized metal nanoparticles in organic solvents. Full article

Silver and gold nanoparticles (NPs) have gained considerable attention in recent years due to their wide-ranging applications in medicine, agriculture, industry, and other fields where they may interact with the environment. Green synthesis of NPs supports sustainability by reducing chemical waste and energy use while improving their biocompatibility through plant phytochemicals. Accordingly, it is important to assess the effects of metal NPs on microorganisms, which play vital roles in ecosystems and biogeochemical cycles. This study aimed to investigate microbial growth dynamics in the presence of green-synthesized silver and gold NPs (using an aqueous extract of Mentha × piperita leaves) and to evaluate potential mechanisms of their interaction. Microorganisms were cultivated in 96-well microtiter plates, and growth curves were analyzed alongside bacterial enumeration on Petri plates. Silver NPs affected the growth of Brevundimonas vesicularis USM1, Pseudarthrobacter oxydans USM2, and Pseudomonas putida USM4, although these strains exhibited partial resistance. In contrast, gold NPs did not inhibit the growth of the tested strains. The ability of Brevundimonas vesicularis USM1 to precipitate metal NPs highlights its potential for sustainable bioremediation applications. The findings contribute to a better understanding of the environmental impact and sustainability aspects of silver and gold NPs in microbial systems. Full article