Powder XRD analysis and catalysis characterization of ultra-small gold nanoparticles deposited on titania-modified SBA-15

Biogenic fabrication of a gold nanoparticle sensor for detection of Fe3+ ions using a smartphone and machine learning

In recent years, smartphones have been integrated into rapid colorimetric sensors for heavy metal ions, but challenges persist in accuracy and efficiency. Our study introduces a novel approach to utilize biogenic gold nanoparticle (AuNP) sensors in conjunction with designing a lightbox with a color reference and machine learning for detection of Fe3+ ions in water. AuNPs were synthesized using the aqueous extract of Eleutherine bulbosa leaf as reductants and stabilizing agents. Physicochemical analyses revealed diverse AuNP shapes and sizes with an average size of 19.8 nm, with a crystalline structure confirmed via SAED and XRD techniques. AuNPs exhibited high sensitivity and selectivity in detection of Fe3+ ions through UV-vis spectroscopy and smartphones, relying on nanoparticle aggregation. To enhance image quality, we developed a lightbox and implemented a reference color value for standardization, significantly improving performance of machine learning algorithms. Our method achieved approximately 6.7% higher evaluation metrics (R 2 = 0.8780) compared to non-normalized approaches (R 2 = 0.8207). This work presented a promising tool for quantitative Fe3+ ion analysis in water.

Titania-mediated stabilization of fluorescent dye encapsulation in mesoporous silica nanoparticles

Mesoporous silica nanoparticles hosting guest molecules are a versatile tool with applications in various fields such as life and environmental sciences. Current commonly applied pore blocking strategies are not universally applicable and are often not robust enough to withstand harsh ambient conditions (e.g. geothermal). In this work, a titania layer is utilized as a robust pore blocker, with a test-case where it is used for the encapsulation of fluorescent dyes. The layer is formed by a hydrolysis process of a titania precursor in an adapted microemulsion system and demonstrates effective protection of both the dye payload and the silica core from disintegration under otherwise damaging external conditions. The produced dye-MSN@TiO2 particles are characterized by means of electron microscopy, elemental mapping, ζ-potential, X-ray diffraction (XRD), nitrogen adsorption, Thermogravimetric analysis (TGA), fluorescence and absorbance spectroscopy and Fourier Transform Infrared Spectroscopy - Total Attenuated Reflectance (FT-IR ATR). Finally, the performance of the titania-encapsulated MSNs is demonstrated in long-term aqueous stability and in flow-through experiments, where owing to improved dispersion encapsulated dye results in improved flow properties compared to free dye properties. This behavior exemplifies the potential advantage of carrier-borne marker molecules over free dye molecules in applications where accessibility or targeting are a factor, thus this encapsulation method increases the variety of fields of application.

Environmentally Friendly Improvement of Plasmonic Nanostructure Functionality towards Magnetic Resonance Applications

Plasmonic nanostructures have attracted a broad research interest due to their application perspectives in various fields such as biosensing, catalysis, photovoltaics, and biomedicine. Their synthesis by pulsed laser ablation in pure water enables eliminating various side effects originating from chemical contamination. Another advantage of pulsed laser ablation in liquids (PLAL) is the possibility to controllably produce plasmonic nanoparticles (NPs) in combination with other plasmonic or magnetic materials, thus enhancing their functionality. However, the PLAL technique is still challenging in respect of merging metallic and semiconductor specific features in nanosized objects that could significantly broaden application areas of plasmonic nanostructures. In this work, we performed synthesis of hybrid AuSi NPs with novel modalities by ultrashort laser ablation of bulk gold in water containing silicon NPs. The Au/Si atomic ratio in the nanohybrids was finely varied from 0.5 to 3.5 when changing the initial Si NPs concentration in water from 70 µg/mL to 10 µg/mL, respectively, without requiring any complex chemical procedures. It has been found that the laser-fluence-insensitive silicon content depends on the mass of nanohybrids. A high concentration of paramagnetic defects (2.2·× 10¹⁸ spin/g) in polycrystalline plasmonic NPs has been achieved. Our findings can open further prospects for plasmonic nanostructures as contrast agents in optical and magnetic resonance imaging techniques, biosensing, and cancer theranostics.

Preparation of Novel Nanoformulation to Enhance Efficacy in the Treatment of Cardiovascular Disease

Despite many efforts over the last few decades, cardiac-based drug delivery systems are experiencing major problems, such as the effective delivery of the precise amount of a drug. In the current study, an effort has been made to prepare a nano-herbformulation (NHF) to overcome the major problem of conventional intervention. Copper oxide-based NHF was prepared using plant extract of Alternanthera sessilis and characterized using physicochemical techniques such as Transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Dynamic light scattering (DLS), UV-Vis spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). TEM analysis revealed that spherical NHF obtained of size 20-50 nm. In addition, XRD and FTIR confirmed the presence of phytochemicals with biological properties over the surface of copper oxide-based NHF. It was demonstrated that dose-dependent antiapoptotic activity was shown against DOX-induced cardiomyocytes, where ROS levels were significantly reduced to 0.29% from 37.99%. The results of the flow cytometry analysis using PI and Annexin staining further confirmed the antiapoptotic activity of NHF against DOX-induced cardiomyocytes by ROS scavenging. Thus, NHF might be used for cardiovascular disease treatment.

Nanoarchitectonics for Ultrathin Gold Films Deposited on Collagen Fabric by High-Power Impulse Magnetron Sputtering

Gold nanoparticles conjugated with collagen molecules and fibers have been proven to improve structure strength, water and enzyme degradation resistance, cell attachment, cell proliferation, and skin wound healing. In this study, high-power impulse magnetron sputtering (HiPIMS) was used to deposit ultrathin gold films (UTGF) and discontinuous island structures on type I collagen substrates. A long turn-off time of duty cycle and low chamber temperature of HiPIMS maintained substrate morphology. Increasing the deposition time from 6 s to 30 s elevated the substrate surface coverage by UTGF up to 91.79%, as observed by a field emission scanning electron microscope. X-ray diffractometry analysis revealed signature low and wide peaks for Au (111). The important surface functional groups and signature peaks of collagen substrate remained unchanged according to Fourier transform infrared spectroscopy results. Multi-peak curve fitting of the Amide I spectrum revealed the non-changed protein secondary structure of type I collagen, which mainly consists of α-helix. Atomic force microscopy observation showed that the roughness average value shifted from 1.74 to 4.17 nm by increasing the deposition time from 13 s to 77 s. The uneven surface of collagen substrate made quantification of thin film thickness by AFM difficult. Instead, UTGF thickness was measured using simultaneously deposited glass specimens placed in an HiPIMS chamber with collagen substrates. Film thickness was 3.99 and 10.37 nm at deposition times of 13 and 77 s, respectively. X-ray photoelectron spectroscopy showed preserved substrate elements on the surface. Surface water contact angle measurement revealed the same temporary hydrophobic behavior before water absorption via exposed collagen substrates, regardless of deposition time. In conclusion, HiPIMS is an effective method to deposit UTGF on biomedical materials such as collagen without damaging valuable substrates. The composition of two materials could be further used for biomedical purposes with preserved functions of UTGF and collagen.

Systematic Incorporation of Gold Nanoparticles onto Mesoporous Titanium Oxide Particles for Green Catalysts

This report describes the systematic incorporation of gold nanoparticles (AuNPs) onto mesoporous TiO2 (MPT) particles without strong attractive forces to efficiently serve as reactive and recyclable catalysts in the homocoupling of arylboronic acid in green reaction conditions. Unlike using nonporous TiO2 particles and conventional SiO2 particles as supporting materials, the employment of MPT particles significantly improves the loading efficiency of AuNPs. The incorporated AuNPs are less than 10 nm in diameter, regardless of the amount of applied gold ions, and their surfaces, free from any modifiers, act as highly reactive catalytic sites to notably improve the yields in the homocoupling reaction. The overall physical properties of the AuNPs integrated onto the MPT particles are thoroughly examined as functions of the gold content, and their catalytic functions, including the rate of reaction, activation energy, and recyclability, are also evaluated. While the rate of reaction slightly increases with the improved loading efficiency of AuNPs, the apparent activation energies do not clearly show any correlation with the size or distribution of the AuNPs under our reaction conditions. Understanding the formation of these types of composite particles and their catalytic functions could lead to the development of highly practical, quasi-homogeneous catalysts in environmentally friendly reaction conditions.

Inkjet-printed paper-based electrochemical sensor with gold nano-ink for detection of glucose in blood serum

An inkjet-printed paper electrode with gold nanoparticle-ink as a non-enzymatic electrochemical sensor for detection of glucose in blood serum is reported.

Amphiphilic phenylalanine derivatives that temporally generate reactive oxygen species from water in the presence of Au(iii) ions

Amphiphilic derivatives of phenylalanine (ADFs) have strong self-assembling propensities and yield low molecular weight hydrogels on multiple occassions. The interaction of ADFs with metal ions can result in the morphological changes in the self-assemblies. Herein, we report the interesting consequences of the interaction between four N-protected ADFs with Au(iii) ions. In the case of ADF 1, the original nanofibrillar morphology of the self-assemblies spontaneously transformed into uniform nanoglobules of ∼80 nm in diameter upon addition of Au(iii) ions. A subsequent reduction of the Au(iii) ions to Au(0) nanoparticles (AuNPs) and the surface decoration of the nanoglobules with AuNPs were observed in the course of the next six to eight hours. Simultaneously, multiple reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂), hydroxyl radicals (˙OH), singlet oxygen and superoxide ions were also found to be present in the reaction medium. These ROS originate from water used as the reaction medium. The ROS production and the reduction of Au(iii) were inhibited upon deaeration of the reaction medium and the use of heavy water (D₂O) or organic solvents as the reaction medium, while an increase in the pH of the aqueous medium intensified both these processes. We exploited the temporal ROS generation using the mixture of 1 and Au(iii) ions towards anticancer therapy by enhancing the intracellular ROS levels. It is expected that this effort can be expanded into a viable anticancer therapy in the near future by modulating the amount and the rate of ROS-generation through judicious choice of the peptidic ligands and metal ions.

Gold nanoparticles: New routes across old boundaries

In recent years, gold nanoparticles have emerged as unique non-invasive drug carriers for targeting drugs to their site of action. Their site specificity has helped in increasing drugs' efficacy at lower dose as well as reduction in their side effects. Moreover, their excellent optical properties and small size offer their utilization as diagnostic tools to diagnose tumors as well as other diseases. This review focuses on various approaches that have been used in last several years for preparation of gold nanoparticles, their characterization techniques and theranostic applications. Their toxicity related aspects are also highlighted. Gold nanoparticles are useful as theranostic agents, owing to their small size, biocompatible nature, size dependent physical, chemical and optical properties etc. However, the challenges associated with these nanoparticles such as scale up, cost, low drug payload, toxicity and stability have been the major impediments in their commercialization. The review looks into all these critical issues and identifies the possibilities to overcome these challenges for successful positioning of metallic nanoparticles in market.

Sono-dispersed MgO over cerium-doped MCM-41 nanocatalyst for biodiesel production from acidic sunflower oil: Surface evolution by altering Si/Ce molar ratios

In the present work, Mobil Composite Material no. 41 (MCM-41) utilized as the catalyst support for biodiesel production from Waste Cooking Oil (WCO). Different amounts of Si/Ce molar ratios (5, 10, 25, 50 and Ce = 0) introduced to the MCM-41 structure to synthesize the bifunctional nanocatalysts and achieve a modified support of high stability and acidity. Then, ultrasound used to disperse MgO active phase on support surface. The prepared nanocatalysts were investigated using various techniques as follows: XRD, EDX, TEM, FESEM, FTIR and BET. The XRD patterns along with the results of FTIR and BET analysis revealed the MCM-41 framework destruction while increasing the Ce content. The FESEM images of the nanocatalysts illustrated a well distribution and uniform morphology for the Mg/CeM (Si/Ce = 10). The particle size and size distribution of the Mg/CeM (Si/Ce = 10) were subsequently determined by TEM and FESEM images. Biodiesel production carried out under following constant operational parameters to evaluate catalytic performance of synthesized samples: T = 70 °C, catalyst loading = 5 wt%, methanol/oil molar ratio = 9, and 6 h reaction time. Ce substitution in support framework considerably enhanced the biodiesel conversion. The Mg/CeM (Si/Ce = 10) nanocatalyst demonstrated the highest conversion of 94.3%. The reusability of the Mg/CeM (Si/Ce = 10) studied in seven reaction cycles and biodiesel conversion reached to 88.7% at the end of seventh cycle which demonstrated its significant stability.

Characterization techniques for nanoparticles: comparison and complementarity upon studying nanoparticle properties

Nanostructures have attracted huge interest as a rapidly growing class of materials for many applications. Several techniques have been used to characterize the size, crystal structure, elemental composition and a variety of other physical properties of nanoparticles. In several cases, there are physical properties that can be evaluated by more than one technique. Different strengths and limitations of each technique complicate the choice of the most suitable method, while often a combinatorial characterization approach is needed. In addition, given that the significance of nanoparticles in basic research and applications is constantly increasing, it is necessary that researchers from separate fields overcome the challenges in the reproducible and reliable characterization of nanomaterials, after their synthesis and further process (e.g. annealing) stages. The principal objective of this review is to summarize the present knowledge on the use, advances, advantages and weaknesses of a large number of experimental techniques that are available for the characterization of nanoparticles. Different characterization techniques are classified according to the concept/group of the technique used, the information they can provide, or the materials that they are destined for. We describe the main characteristics of the techniques and their operation principles and we give various examples of their use, presenting them in a comparative mode, when possible, in relation to the property studied in each case.

Sonochemical and sustainable synthesis of graphene-gold (G-Au) nanocomposites for enzymeless and selective electrochemical detection of nitric oxide

In this study, a sonochemical approach was utilised for the development of graphene-gold (G-Au) nanocomposite. Through the sonochemical method, simultaneous exfoliation of graphite and the reduction of gold chloride occurs to produce highly crystalline G-Au nanocomposite. The in situ growth of gold nanoparticles (AuNPs) took place on the surface of exfoliated few-layer graphene sheets. The G-Au nanocomposite was characterised by UV-vis, XRD, FTIR, TEM, XPS and Raman spectroscopy techniques. This G-Au nanocomposite was used to modify glassy carbon electrode (GCE) to fabricate an electrochemical sensor for the selective detection of nitric oxide (NO), a critical cancer biomarker. G-Au modified GCE exhibited an enhanced electrocatalytic response towards the oxidation of NO as compared to other control electrodes. The electrochemical detection of NO was investigated by linear sweep voltammetry analysis, utilising the G-Au modified GCE in a linear range of 10-5000μM which exhibited a limit of detection of 0.04μM (S/N=3). Furthermore, this enzyme-free G-Au/GCE exhibited an excellent selectivity towards NO in the presence of interferences. The synergistic effect of graphene and AuNPs, which facilitated exceptional electron-transfer processes between the electrolyte and the GCE thereby improving the sensing performance of the fabricated G-Au modified electrode with stable and reproducible responses. This G-Au nanocomposite introduces a new electrode material in the sensitive and selective detection of NO, a prominent biomarker of cancer.

The growth mode of ZnO on HZSM-5 substrates by atomic layer deposition and its catalytic property in the synthesis of aromatics from methanol

The resulting ZnO film on zeolites could effectively prevent exposing the HZSM-5 framework to steam during the reaction and regeneraton processes.

Gold nanoparticles alter parameters of oxidative stress and energy metabolism in organs of adult rats

This study evaluated the parameters of oxidative stress and energy metabolism after the acute and long-term administration of gold nanoparticles (GNPs, 10 and 30 nm in diameter) in different organs of rats. Adult male Wistar rats received a single intraperitoneal injection or repeated injections (once daily for 28 days) of saline solution, GNPs-10 or GNPs-30. Twenty-four hours after the last administration, the animals were killed, and the liver, kidney, and heart were isolated for biochemical analysis. We demonstrated that acute administration of GNPs-30 increased the TBARS levels, and that GNPs-10 increased the carbonyl protein levels. The long-term administration of GNPs-10 increased the TBARS levels, and the carbonyl protein levels were increased by GNPs-30. Acute administration of GNPs-10 and GNPs-30 increased SOD activity. Long-term administration of GNPs-30 increased SOD activity. Acute administration of GNPs-10 decreased the activity of CAT, whereas long-term administration of GNP-10 and GNP-30 altered CAT activity randomly. Our results also demonstrated that acute GNPs-30 administration decreased energy metabolism, especially in the liver and heart. Long-term GNPs-10 administration increased energy metabolism in the liver and decreased energy metabolism in the kidney and heart, whereas long-term GNPs-30 administration increased energy metabolism in the heart. The results of our study are consistent with other studies conducted in our research group and reinforce the fact that GNPs can lead to oxidative damage, which is responsible for DNA damage and alterations in energy metabolism.

Adsorption of p-nitrothiophenol on mesostructured polyoxometalate–silicate–surfactant composites containing Au nanoparticles: study of surface-enhanced Raman scattering activity

When DMAB-functionalized Au-NPs@EPSS acts as the SERS substrate, the detection sensitivity of p-NTP molecules increases by ∼6 times compared with as-synthesized Au-NPs@EPSS.

Platinum covering of gold nanoparticles for utilization enhancement of Pt in electrocatalysts

This work attempts to enhance platinum utilization in a Pt-based electrocatalyst by the tuned covering of gold nanoparticles with small Pt entities. Reductive deposition of Pt on Au nanoparticles of two size ranges (Au-I: 10 +/- 1.2 nm, Au-II: 3 +/- 0.6 nm) up to different atomic Pt : Au ratios (m) was used to prepare two series of samples named Pt(m)insertion markAu-I and Pt(m)insertion markAu-II particles, respectively. The obtained Pt(m)insertion markAu particles were characterized with TEM, XPS, UV-Vis and XRD techniques, and then loaded on conventional Vulcan XC-72 carbon to make Pt(m)insertion markAu/C electrocatalysts. Cyclic voltammetry (CV) measurements showed that the electrochemical active surface area (EAS) and Pt utilization (U(Pt)) in Pt(m)insertion markAu/C were enhanced remarkably at m< or = 0.2 for Pt(m)insertion markAu-I/C or m< or = 0.5 for Pt(m)insertion markAu-II/C, in comparison to conventional Pt/C electrocatalyst. In particular, U(Pt) was enhanced to nearly 100% in Pt(m)insertion markAu-I/C catalysts at m< or = 0.05 and in Pt(m)insertion markAu-II/C at m< or = 0.1. In the CV measurement of methanol electro-oxidation, the specific mass activity of Pt in Pt(m)insertion markAu/C catalysts was found in proportional to U(Pt), confirming that the enhancement of Pt utilization is essential for the development of highly active Pt-based electrocatalysts. The highly dispersed Pt entities on Au nanoparticles proved to be stable during the electro-oxidation of methanol. Our study also showed that the use of smaller Au nanoparticles is advantageous for the generation of more active Pt catalyst at higher atomic Pt : Au ratios.

Effect of Supporting Surface Layers on Catalytic Activities of Gold Nanoparticles in CO Oxidation

The surfaces of fumed silica materials were modified with a surface sol-gel process for catalysis applications. This surface-modification approach allows not only a monolayer growth of TiO(2) or Al(2)O(3) but also a stepwise double-layer growth of TiO(2)/TiO(2), Al(2)O(3)/Al(2)O(3), TiO(2)/Al(2)O(3), or Al(2)O(3)/TiO(2) on the surfaces of the silica materials with a monolayer precision. XRD analyses revealed that the coated monolayers and double layers of TiO(2) and Al(2)O(3) were amorphous. Gold nanoparticles were successfully deposited on the above six surface-modified silica materials via a deposition-precipitation method. The catalytic activities of these six gold catalysts for CO oxidation are highly dependent on the structures of their surface monolayers or double layers. The gold catalyst supported on the silica material functionalized with a TiO(2) monolayer (Au/TiO(2)) is the most active in both as-synthesized and oxidized forms, while the gold catalyst supported on the silica material functionalized with an Al(2)O(3)/TiO(2) double layer (Au/Al(2)O(3)/TiO(2)/SiO(2)) is the most active in the reduced form among the six catalysts. Surprisingly, the gold catalyst supported on the silica material functionalized with a TiO(2)/Al(2)O(3) double layer (Au/TiO(2)/Al(2)O(3)/SiO(2)) has much less activity than Au/Al(2)O(3)/TiO(2)/SiO(2) under all various treatments, underscoring the sensitivity of the catalytic activity to the structure of the supporting surfaces.