Surface Plasmon Resonance Absorption Research Articles

Biosynthesis and Characterizations of Gold Nanoparticles (AuNPs) Prepare Using Different Age Classes of <i>Marphysa moribidii </i>(Polychaetes) Extract as Biogenic Reducing Agents

The utilization of Marphysa moribidii, a local marine baitworm (Polychaeta), as a possible biogenic reducing agent in the synthesis of AuNPs was successfully performed. In this particular study, different age classes of M. moribidii based on their body widths that classified as Class I (3 – 5 mm), Class II (6 – 8 mm), and Class III (9 – 11 mm) were employed in the biosynthesis of AuNPs. The use of different age classes of M. moribidii for the biosynthesis of AuNPs is a fascinating approach that takes advantage of the varying metabolic activities of the different age groups. The colour changes of the solution from yellow to red ruby is the initial observation for the successful biosynthesis of AuNPs where AuNPs_II shows the fastest changes of colour after 2 h incubation and maintains stable for over 1 month of storage. Further confirmation was depicted from the existence of surface Plasmon resonance (SPR) absorption peaks in a range of 545 – 552 nm from UV-Vis spectroscopy. TEM analysis shows the formation of spherical-like shape of biosynthesis AuNPs with average particle size around 42 – 57 nm where AuNPs_II had the smaller particle size. Lastly, the antibacterial assessment of biosynthesized produced from different age classes of M. moribidii had good antibacterial activity against Gram-negative bacteria, but poor activity against Gram-positive bacteria. AuNPs produced from Class II M. moribidii (AuNPs_II) provide the highest ZOI value of 13 mm. The utilization of different age classes of M. moribidii for the biosynthesis of metal nanoparticles is an interesting pathway for designing a novel method that can be considered nature-friendly, safe, and hopeful for the future.

Mercury-Mediated Epitaxial Accumulation of Au Atoms for Stained Hydrogel-Improved On-Site Mercury Monitoring.

Trivalent Au ions are easily reduced to be zerovalent atoms by coexisting reductant reagents, resulting in the subsequent accumulation of Au atoms and formation of plasmonic nanostructures. In the absence of stabilizers or presence of weak stabilizers, aggregative growth of Au nanoparticles (NPs) always occurs, and unregular multidimensional Au materials are consequently constructed. Herein, the addition of nanomole-level mercury ions can efficiently prevent the epitaxial accumulation of Au atoms, and separated Au NPs with mediated morphologies and superior plasmonic characteristics are obtained. Experimental results and theoretical simulation demonstrate the Hg-concentration-reliant formation of plasmonic nanostructures with their mediated sizes and shapes in the presence of weak reductants. Moreover, the sensitive plasmonic responses of reaction systems exhibit selectivity comparable to that of Hg species. As a concept of proof, polymeric carbon dots (CDs) were used as the initial reductant, and the reactions between trivalent Au and CDs were studies. Significantly, Hg atoms prevent the epitaxial accumulation of Au atoms, and plasmonic NPs with decreased sizes were in situ synthesized, corresponding to varied surface plasmonic resonance absorption performance of the CD-induced hybrids. Moreover, with the integration of sensing substrates of CD-doped hydrogels, superior response stabilities, analysis selectivity, and sensitivity of Hg2+ ions were achieved on the basis of the mercury-mediated in situ chemical reactions between trivalent Au ions and reductant CDs. Consequently, a high-performance sensing strategy with the use of Au NP-staining hydrogels (nanostaining hydrogels) was exhibited. In addition to Hg sensing, the nanostaining hydrogels facilitated by doping of emerging materials and advanced chem/biostrategies can be developed as high-performance on-site monitoring routes to various pollutant species.

A novel highly active AgMOF-based silver single-atom catalyst and its application to the aptamer SERS/RRS for the determination of aflatoxin B1

A novel highly active silver single-atom catalyst (AgSAC) was prepared by a microwave-assisted solvothermal method using silver covalent organic frameworks (AgMOF) as precursors. It was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared (IR), and surface-enhanced Raman scattering (SERS). The experiment found that AgSAC has excellent catalytic performance and can heavily catalyze the nano-reaction of chloroauric acid-malic acid (HAuCl4–H2Mi) to generate gold nanoparticles (AuNPs). The produced AuNPs have strong SERS, resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs) signals. Aflatoxin B1 aptamer (AptAFB1) can be adsorbed to the surface of AgSAC through electrostatic interaction, to reduce the catalytic activity of AgSAC and the SERS/RRS/Abs signal of the system. When the target molecule (AFB1) was added, it will specifically bind to AptAFB1 and release AgSAC, restoring the catalytic activity of AgSAC, thereby restoring the SERS/RRS/Abs signal of the system. Based on this, a simple and sensitive aptamer sensing analysis platform for trace AFB1 was established, and a reasonable catalytic amplification mechanism of AgSAC was proposed. The SERS method exhibited the highest sensitivity, with a linear range of 0.005–0.225 μg/L and a detection limit of 0.002 μg/L.

STRUCTURAL INVESTIGATION OF HETERO-STRUCTURED CORE-SHELL SILVER-SILICA HYBRID AS A POTENTIAL AGRO-SENSOR MATERIAL

Investigation into the novel synthesis and structural properties of Heterostructured core shell Silver-Silica (AgSiO2) Nanohybrid is reported herein, for possible utilization as humidity sensing material in Agricultural post-harvest humidity monitoring system and greenhouse farming. The Heterostructured nanoparticles (Ag and SiO2) were synthesized via a chemical reduction method. Structural characterizations were done using X-ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), UV-Visible spectroscopy, Energy Dispersive X-ray (EDX) spectroscopy and N2 adsorption-desorption techniques. The XRD diffractogram of Ag-SiO2 showed distinct peaks at 2? values of 390, 430, 660 and 790 which was corroborated by the SEM and HRTEM results. EDX convincingly confirmed Ag and SiO2 incorporation into the Ag-SiO2 nanocomposite hetero-structure at 16.7 % and 83.3 % respectively. A Surface Plasmon Resonance absorption peak of 421 nm of Ag was revealed by UV-Visible spectroscopic analysis. An effective and relatively narrow pore size distributions of 3 – 8 nm was revealed by N2 adsorption-desorption for the Ag-SiO2 Nanocomposite. Overall, these properties are promising for effective use as humidity sensing material.

Facile Synthesis of PVP-Coated Silver Nanoparticles and Evaluation of Their Physicochemical, Antimicrobial and Toxic Activity

This study focuses on the synthesis of silver nanoparticles (AgNPs) at different high concentrations and investigates their physicochemical properties, antimicrobial activity, and cytotoxicity. AgNPs were synthesized using the alcohol reduction process, involving the reduction of AgNO3 and its subsequent stabilization via PVP at 80 °C for 4 h. The AgNO3/PVP molar ratio and the average molecular weight were modified in this study. Characterization analyses revealed that the synthesized AgNPs exhibited characteristic surface plasmon resonance absorption peaks at approximately 415 nm, as observed in the UV–Vis spectrum. The results presented in X-ray diffractograms confirmed the face-centered cubic structure of metallic Ag in the nanoparticles. The nanoparticles demonstrated uniform size and shape, with controllable dimensions ranging from 3 to 800 nm. Regarding antimicrobial activity, the MIC solutions exhibited higher potency against the planktonic cells of Candida albicans. The determination of inhibition halos indicated that the silver nanoparticles had an impact on the microorganisms Streptococcus mutans, Candida albicans, and Actinomyces israelii. Furthermore, lower-concentration compositions showed reduced cytotoxic effects compared to higher-concentration particles. Based on the findings, it was concluded that the AgNO3/PVP molar ratio plays a crucial role in the production of AgNPs. These synthesized nanoparticles exhibit desirable physicochemical properties and demonstrate potential antimicrobial activity and controlled cytotoxicity.

Eco-Friendly Synthesis of Silver Nanoparticles Using Aqueous Extract of Ziziphus Spina-Christi Seeds: Characterization and Stability

In this study, silver nanoparticles (Ag-NPs) were prepared using an aqueous extract of Ziziphus Spina-Christi Seeds (ZSCS) powder as an eco-friendly material, reducing agent and capping ligand. The synthesized Ag-NP was characterized using UV-visible absorption spectroscopy (UV-Vis), Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS). From The UV-Vis spectra, the surface plasmon resonance (SPR) absorption band at 443 nm confirmed the formation of Ag-NPs. The TEM results demonstrated that the synthesized Ag-NPs have mostly spherical shapes with a particle size of 21.54 nm. In addition, the particle size and the specific surface area (SSA) of Ag-NPs decreased with increasing ZSCS powder extract volume and AgNO3 concentration. The basic medium was found to be better than the acidic medium to prepare Ag-NPs. At a pH value equal to 9.5, within 30 minutes, the color of the solution was changed from colorless to brownish-orange. SPR absorption band of Ag-NPs demonstrated that the synthesized Ag-NPs have high stability over a period of 8 months. From FTIR results, the stretching of C-O group at 1223 and 1031 cm-1 disappeared after bioreduction of AgNO3, these results may be due to that Ag reduction was carried out by some hydroxyl groups that get oxidized at the expense of Ag+ because Ag+ is reduced to Ag-NPs.

Gold-Nanorod-Assisted Live Cell Nuclear Imaging Based on Near-Infrared II Dark-Field Microscopy.

Dark-field microscopy offers several advantages, including high image contrast, minimal cell damage, and the absence of photobleaching of nanoprobes, which make it highly advantageous for cell imaging. The NIR-II window has emerged as a prominent research focus in optical imaging in recent years, with its low autofluorescence background in biological samples and high imaging SBR. In this study, we initially compared dark-field imaging results of colorectal cancer cells in both visible and NIR-II wavelengths, confirming the superior performance of NIR-II imaging. Subsequently, we synthesized gold nanorods with localized surface plasmon resonance (LSPR) absorption peaks in the NIR-II window. After bio-compatible modification, we non-specifically labeled colorectal cancer cells for NIR-II dark-field scattering imaging. The imaging results revealed a sixfold increase in SBR, especially in the 1425-1475 nm wavelength range. Finally, we applied this imaging system to perform dark-field imaging of cell nuclei in the NIR-II region and used GNRs for specific nuclear labeling in colorectal cancer cells. The resulting images exhibited higher SBR than non-specifically-labeled cell imaging, and the probe's labeling was precise, confirming the potential application of this system in photothermal therapy and drug delivery for cancer cells.

Discriminative detection of morphine and methamphetamine-like street samples by label-free Cu doped-silver nanoparticles chemosensor

This research provides a straightforward and sensitive method for detecting morphine (MOR) and methamphetamine (MET) by colorimetry. In order to characterize the nanoprobe as it was prepared, XRD, FT-IR, XPS, UV–vis, TEM, ICP, DLS, and EDS analyses were conducted. We evaluated the performance of Ag/Cu nanoparticles for colorimetric sensing of MOR and MET. As well as naked-eye detection (photographs), UV–visible spectroscopy was used to monitor and record the results. Color shifts of colloidal NP solutions or surface plasmon resonance (SPR) absorbance bands were used to differentiate between MOR and MET, leading to the discovery that NP could distinguish between the two. Based on the linearity of the calibration curves' ranges, MOR and MET were found to have different limits of detection (LODs), which are 0.21 µg/mL and 0.49 µg/mL for each, respectively. In addition, they displayed a linear range of 0–50 µg/mL and 0–100 µg/mL, for MOR and MET, respectively. When Ag/Cu NPs are exposed to MOR and MET, they aggregate and exhibit noticeable color changes. For MOR, the changes ranged from bright yellow to smoky, while for MET, they were dark orange. The optimal incubation time for sensing MOR and MET was 7 and 35 min, respectively.

Polychaeta-mediated synthesis of gold nanoparticles: A potential antibacterial agent against Acute Hepatopancreatic Necrosis Disease (AHPND)–causing bacteria, Vibrio parahaemolyticus.

Gold nanoparticles (AuNPs) have emerged as a promising application in aquaculture. Their nano-sized dimensions, comparable to pathogens offer potential solutions for combating antibiotic resistance. In this study, AuNPs were synthesized by using polychaetes, Marphysa moribidii as the bio-reducing agent. Modifications were made to reduce agglomeration in green-synthesized AuNPs through ultrasonication. The antibacterial activities of AuNPs against V. parahaemolyticus were evaluated. The physicochemical characteristics of the green synthesized AuNPs were comprehensively investigated. The successful formation of AuNPs was confirmed by the appearance of a red ruby colour and the presence of surface Plasmon resonance (SPR) absorption peaks at 530 nm as observed from UV–vis spectroscopy. Scanning electron microscopy (SEM) revealed spherical-shaped AuNPs with some agglomerations. Transmission electron microscopy (TEM) showed particle size of AuNPs ranging from 10 nm to 60 nm, meanwhile dynamic light scattering (DLS) analysis indicated an average particle size of 24.36 nm. X-ray diffraction (XRD) analysis confirmed the high crystallinity of AuNPs, and no AuNPs were detected in the polychaetes extracts prior to synthesis. A brief ultrasonication significantly reduced the tendencies for AuNPs to coalesce. The green-synthesized AuNPs demonstrated a remarkable antibacterial efficacy against V. parahaemolyticus. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests revealed that a concentration of 0.3 g/ml of AuNPs effectively inhibited V. parahaemolyticus. These findings highlighted the potential of green-synthesized AuNPs as antibacterial agents for the prevention and management of AHPND in aquaculture.

Efficacy of 15 nm Gold Nanoparticles for Image-Guided Gliosarcoma Radiotherapy

Targeted brain cancer treatments are sorely needed to improve long-term prognosis, particularly for gliosarcoma and glioblastoma patients. Gold nanoparticles (GNPs) have unique properties including high atomic number, biocompatibility, and small size for cancer cell internalization. GNPs are consequently an ideal candidate for improved cancer targeting using image-guided radiotherapy. This work investigated 15 nm AuroVistTM GNPs for image-guided gliosarcoma radiotherapy and identified optimum GNP concentrations. The GNPs were found to be 15–20 nm using optical surface plasmon resonance absorption, with a (41.3 ± 0.3) nm hydrodynamic diameter. Confocal imaging showed that 50–500 µg/mL of the GNPs was well-internalized into the 9L cells within 24–48 h. γ-H2AX assays showed that 50–500 µg/mL of the GNPs radiosensitized the 9L cells irradiated with 125 and 150 kVp X-rays. However, only 500 µg/mL of the GNPs produced significant long-term dose enhancement with 150 kVp X-rays (with a sensitization enhancement ratio at 10% survival of 1.43, and 1.13 with 50 µg/mL) using clonogenic assay. CT imaging of the GNPs in the 9L tumors in Fischer rats further showed that GNP concentrations above 500 µg/mL were required to distinguish the tumor from the brain, and the GNPs were detected 48 h after injection. These promising results indicate that the GNPs can be used for selective gliosarcoma treatment with image-guided X-ray radiotherapy at concentrations above 500 µg/mL.

Dual signal AA detection based on fluorescence and local surface plasmon resonance absorption technology

The core/shell Au@MnO2 nanoparticles (Au@MnO2 NPs) were prepared and characterized by UV–vis spectrum, transmission electron microscopy (TEM) and X-ray photoelectron spectrum (XPS). It was found that MnO2 in the shell of Au@MnO2 NPs could oxidize thiamine (VB1) into blue fluorescent thiochrome (TC). The reduction of MnO2 in the shell layer could lead to a decrease of Au@MnO2 NPs size along with a blue shift of the localized surface plasmon resonance (LSPR) peak. Once ascorbic acid (AA) was introduced, MnO2 in the shell was rapidly reduced to Mn2+ ions. Accordingly, the oxidation of VB1 was inhibited and the fluorescence of TC was weakened. Based on these phenomena, we have established a dual signal method for AA determination with the help of UV–vis and fluorescence spectrophotometer. Under the optimum conditions, the LSPR absorption peak shift (Δλ) of Au@MnO2 NPs and the decrease in fluorescence of TC correlated well with AA concentration ranging from 0.75 to 17.5 μM. The detection limits of LSPR absorption assay and fluorescence assay were 0.18 and 0.47 μM, respectively. More importantly, this dual-signal detection method has been used for the determination of AA in vitamin C tablets with high accuracy and precision, indicating its promising potential applications.

Suppression of polarization instability in ultrashort Fabry–Pérot fiber laser

Due to the weak birefringence from the intracavity fiber, vector solitons are easily generated in GHz-fundamental-repetition-rate mode-locked fiber lasers, which can exhibit diverse time-varying polarization dynamics. These soliton dynamics can lead to polarization instability of the pulse train, which prevents industrial and scientific applications that require stable and uniform pulse trains. However, it is hard to suppress the polarization instability due to insufficient space for inserting traditional polarizers and difficulties in enhancing the fiber birefringence in the ultrashort fiber laser cavity. To this end, here we propose an alternative method that can effectively transform the vector solitons into scalar solitons by exploring gold nanorod (GNR) film as a polarizer in the laser cavity. First, the theoretical studies of polarization dynamics in ultrashort Fabry–Pérot (FP) fiber lasers with and without intracavity GNR film are conducted. The results indicate that the use of GNR film can significantly suppress the polarization instability and generate scalar solitons. Then, the large-scale preparation of GNRs with longitudinal surface plasmon resonance absorption peak of >1380 nm is realized by a two-step seed-mediated method, and the GNR film with an operation wavelength range covering the C + L band is fabricated by electrospinning. Finally, we apply the GNR film to a 2-cm-long FP fiber laser, and convert polarization rotation vector solitons to linearly polarized solitons (LPSs) at 1.5 μm. The polarization extinction ratio of the improved LPS pulse train is up to 33 dB.

Physicochemical robustness of pulse laser ablated silver-copper nanocomposoites against varied bacterial strains

Nanocomposites (NCs) of inorganic materials with controlled physicochemical characteristics became beneficial for diverse biomedicine and pharmacology applications. Thus, some new types of crystalline spherical silver (Ag)/copper (Cu) nanocomposites (Ag–CuNCs) were made at various laser fluences (ranged from 0 to 14.15 ± 3.9 J cm−2) using the pulsed laser ablation in liquid (PLAL) approach and characterized for the first time. The structures, morphologies, optical and bactericidal properties of these colloidal NCs were determined and the results for the best sample are presented. These NCs showed distinct surface plasmon resonance absorption bands at 402 and 580 nm accompanied by a blue shift. FTIR spectra verified the dispersion of pure Ag–CuNCs in deionized water and XRD pattern confirmed their crystalline nature. EDX analysis of samples confirmed their high purity with appropriate elemental distribution. HRTEM image of the optimum sample exhibited the presence of spherical Ag–CuNCs of mean diameter ≈ 6 ± 1.3 nm and lattice spacing of 0.073 nm and 0.155 nm. Model simulated optimized structure of Ag–CuNCs reaffirmed their stability and chemically reactive HOMO-LUMO isopotential surface. The antibacterial potential of the produced Ag–CuNCs was evaluated using the inhibition zone diameter (IZD) and optical density (at 600 nm) measurements. The optimum Ag–CuNCs prepared at 14.15 ± 3.9 J cm−2 when tested against E. coli, P. aeruginosa, B. subtilis and S. aureus bacteria showed the IZD of 23, 24, 21 and 22 mm, respectively. It was shown that by tuning the laser fluence, the physicochemical and bactericidal attributes of the proposed Ag–CuNCs can be customized, that may have significant implications for potential uses in nanomedicine.

An ultrahigh-resolution multicolor sensing platform via target-induced etching of gold nanorods for multi-colorimetric analysis of trace silver ions

Heavy metal ion pollution is a pressing global concern with detrimental effects on the environment and human health. To address this issue, we have developed an ultrahigh-resolution multicolor sensing platform for the specific detection of silver ions (Ag(I)). The method employs the nanozyme of platinum nanoparticles (PtNPs) as a link to control the etching of gold nanorods (AuNRs). Through specific binding with Ag(I), the PtNPs hinder the catalase-like activity responsible for hydrogen peroxide (H2O2) decomposition. This inhibition enables the Fenton reaction between H2O2 and ferrous ions, generating highly oxidizing hydroxyl free radicals (·OH). The resulting etching of AuNRs induces a blue-shift in their local surface plasmon resonance (LSPR) absorption spectra. The degree of blue-shift is directly proportional to the Ag(I) concentration, facilitating trace-level detection. Furthermore, the aspect ratio change of the AuNRs yields distinguishable colors. In contrast to common multicolor sensors relying on nanozyme horseradish peroxidase (HRP) activity, which exhibits an inverse relationship between AuNR etching and target concentration, our approach demonstrates a proportional response. This unique characteristic enables ultrahigh-resolution multicolor detection of Ag(I) visible to the naked eye. We anticipate that this innovative sensing platform will pave the way for nanosensor development in environmental monitoring and food safety detection.

Combined density functional theory and boundary element methods study on optical and electronic properties of interfacial Au/TiO2 defects

This study investigates the optical and electrical properties of Au/TiO2 nanoparticles with different sizes and defects by combining micro- and macro-scale simulations through density functional theory (DFT) and boundary element method (BEM), respectively. The O-vacancy in the sample enhances the bonding and the electron transfer at the Au/TiO2 perimeter zone, as indicated by the binding energy and charge density difference in DFT calculations, respectively. BEM simulation indicates a stronger electromagnetic field in the Au/TiO2 interface of the sample with O-vacancy. DFT calculations demonstrate that the optical absorption of Au/TiO2 in the ultraviolet range is well described by the absorption coefficient spectra, whereas the BEM results well describe the range of the surface plasmon resonance absorption of Au/TiO2 in the wavelength range of 480–550 nm through the absorption cross-section. This study demonstrates the combined role of DFT and BEM in studying the electrical and optical properties of the nanocrystal system.

Effect of Postdeposition Heat Treatment on the Nanoplasmonic Behavior of Glancing Angle‐Deposited Silver Nanostructures

Postdeposition heat treatment‐induced modifications of nanoplasmonic response in glancing angle‐deposited (GLAD) Ag nanostructures are systematically investigated. The as‐deposited GLAD Ag thin films are annealed at various temperatures namely 200, 250, 300, and 350 °C in air atmosphere. The reduction in localized surface plasmon resonance (LSPR) absorption peak width is detected with annealing. Morphological characterization of the as‐deposited and annealed films reveals reduction in grain size and shape distributions responsible for narrowing of the LSPR peak width. The refractive index sensitivities of the as‐deposited and annealed films are measured using an in‐house‐developed optical setup and figure of merit (FOM) of the sensors is also estimated. An increase in FOM of the sensors is observed upon annealing while sensitivity is found to be reduced. E‐field profile surrounding the Ag nanoparticles is also simulated to explain the experimental observations on refractive index sensitivity of the films.

Facile phytosynthesis of gold nanoparticles using Nepeta bodeana Bunge: Evaluation of its therapeutics and potential catalytic activities

In the present study, the ethanol extract of leaves of Nepeta bodeana Bunge was utilized in environmentally friendly synthesis of gold nanoparticles (AuNPs) via an immediate, one-step, and cost-effective process. The biosynthesized AuNPs were characterized using a variety of techniques, including UV–visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and laser Doppler electrophoresis (zeta potential), among others. Pink in hue, the manufactured AuNPs were practically spherical and had<20.5 nm in diameter. The peak of the localized surface plasmon resonance absorption band at 547 nm helped to explain the biogenic synthesis of AuNPs, which used the ethanolic extract of the Nepeta bodeana leaves. In addition to this, the biosynthesized AuNPs possessed the remarkable stability as a result of their zeta potential value of − 22.3 mV. The green synthesized AuNPs demonstrated the excellent catalytic activity because they were able to catalytically degrade methylene blue (MB) at a variety of concentrations. The results indicated that 94.2% of MB were degraded after 10 min. They also showed a remarkable antibacterial activity against both Gram-nrgative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus and Bacillus cereus) bacteria. In addition, a proper antifungal activity with the minimum inhibitory concentration (MIC) values of 50 and 25 μg/mL against Candida albicans and Aspergillus niger, respectively, were determined. The phytosynthesized AuNPs indicated a considerable antioxidant activity of 83% and 74% in the applied DPPH and ABTS radical scavenging activity tests, respectively. The anti-inflammatory properties of the synthesized AuNPs were established to be dose-dependent and varied from 11% to 76%. The green synthesized AuNPs also exhibited a concentration-dependent cytotoxicity on human liver (HepG2) and breast (MCF-7) cancer cells, which were around 77.4 and 71.2% at 300 µg/mL, respectively. They showed as well a notable anti-diabetic activity with the 52% inhibition of α-amylase and the 62% glucose uptake activity by yeast cells at 300 µg/mL. All these findings suggested that the produced AuNPs could be explored for developing many therapeutic as well as catalytic useful products.

Green Synthesis of Magnetic Supramolecules β-Cyclodextrin/Iron Oxide Nanoparticles for Photocatalytic and Antibacterial Applications.

Iron oxide nanoparticles (Fe3O4NPs) are a fascinating field of study due to their wide range of practical applications in environmental and medical contexts. This study presents a straightforward, environmentally friendly method for producing Fe3O4NPs utilizing β-cyclodextrin (β-CD) as a reducing and capping agent. This approach results in the rapid and effective eco-friendly synthesis of β-CD/Fe3O4NPs. The properties and characteristics of β-CD/Fe3O4NPs were investigated using various methods, including ultraviolet-visible (UV/vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetry analysis (TGA), and vibrating-sample magnetometry (VSM). The absorption of β-CD/Fe3O4NPs caused a distinct peak at 349 nm, as evidenced by the results of UV/vis studies. This peak was attributed to the absorption of surface plasmon resonance. The crystalline nature of β-CD/Fe3O4NPs was confirmed through XRD analysis. The SEM and TEM analyses have verified the geometry and structural characteristics of β-CD/Fe3O4NPs. The β-CD/Fe3O4NPs exhibited remarkable effectiveness in the decomposing efficiency (%) of methylene blue (MB) dye with 52.2, 94.1, and 100% for 0.2, 0.4, and 0.6 g β-CD/Fe3O4NPs, respectively. In addition, the highest efficiency in hunting radicals was observed (347.2 ± 8.2 mg/g) at 100 mg/mL β-CD/Fe3O4NPs; the combination of β-CD/Fe3O4NPs exhibited remarkable effectiveness in inhibiting the growth of some bacteria that cause infections. The capabilities of β-CD/Fe3O4NPs for various applications showed that these materials could be used in photocatalytic, antioxidants, and antibacterial. Additionally, the eco-friendly synthesis of these materials makes them a promising option for the remediation of harmful pollutants and microbes.

Surface grafted gold nanorods (GNRDs) using thermosensitive copolymers with various transition temperatures: Nanomaterials with potential application for photothermal therapy

A series of diblock copolymers containing a biocompatible polyethylene glycol (PEG) block and a thermoresponsive poly(N-vinyl caprolactam) (PNVCL) based block, were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The cloud point temperature (Tcp) in water of the diblocks was adjusted from 35 to 42 °C by adding N-vinyl pyrrolidone (NVP) units in the thermoresponsive block. The terminal trithiocarbonate group evolving from the RAFT agent used in the synthesis, was modified to thiol to stabilize gold nanorods (GNRDs) via a “grafting-to” approach. Stability of the PEG-b-P(NVCL-co-NVP)@GNRDs nanomaterials was monitored during 8 days; where the localized surface plasmon resonance (LSPR) absorption band did not shifted or showed any broadening. Aqueous dispersed samples were irradiated with near-infrared laser light for 10 min, observing a temperature increase from 25 to 50 °C depending on the laser optical power (between 100 and 500 mW); while no precipitation was observed. For temperatures above the cloud point temperature of the copolymers (Tcp), the formation of aggregates in sizes around 200 nm was observed without precipitation. This study demonstrates that the stabilization of gold nanorods by grafting with the title thermoresponsive block copolymers, and the observed temperature-dependent block-copolymer@GNRD aggregation, has potential uses in drug-delivery applications for photothermal therapy.

Solution‐Processable Three‐Dimensional Metamaterials with Ultrahigh Broadband Absorption for Photothermal Electronic Conversion

AbstractMetamaterials are promising candidates for broadband light absorbers, but complex manufacturing procedures with expensive instruments have limited their practical applications. Herein, this work develops an all‐solution‐processed three‐dimensional (3D) metamaterial—based on a gold nanocage (GNC)/silk fibroin (SF) nanocomposite thin film—that achieves near‐unity (&gt;94%) and broadband (350–2000 nm) light absorption. At a low particle density, the film exhibits a typical signal for localized surface plasmon resonance (LSPR) absorption at 856 nm, originating from its hollow geometrical shape of GNCs. In contrast, at high particle densities the films display ultrahigh broadband absorption, even in the non‐LSPR regions. This work attributes this behavior to the highly dense GNCs dispersed uniformly in the SF matrix acting optically as extremely fragmented metallic films, thereby retaining the highly absorptive nature of the metal while strongly suppressing its highly reflective properties. Moreover, the metamaterial absorber displays a desirable broadband‐light‐induced photothermal effect when illuminated with a halogen lamp. Finally, investigations into the photothermal electronic properties of this metamaterial combined with an Al/Si Schottky diode reveal an excellent photoresponse and photostability. The as‐designed systems can function at telecommunication wavelengths longer than the typical operation wavelengths of Si‐based devices. Such 3D metamaterial absorbers can be efficient platforms for various photothermal applications.