High Surface Area Nanoparticles Research Articles

Sustainable and Flexible Surface-Enhanced Raman Scattering Transducer: Gold Nanoparticle-Bacterial Cellulose Composite for Pesticide Monitoring in Agrifood Systems

Functionalized plasmonic nanostructure platforms are widely used for developing optical biosensors and SERS assays. In this work, we present a low-cost and scalable surface-enhanced Raman scattering (SERS) system based on an innovative optical transducer comprising gold nanoparticles (AuNPs) embedded in nano-fibrillated bacterial cellulose (BC). The AuNPs@BC composite leverages the unique nanofibrillar architecture of bacterial cellulose, which provides a high surface area, flexibility, and uniform nanoparticle distribution, enabling the formation of numerous electromagnetic “hot spots”. This structure excites localized surface plasmon resonance (LSPR), as demonstrated by a bulk sensitivity of 72 nm/RIU, and supports enhanced Raman signal amplification. The eco-friendly and disposable AuNPs@BC platform was tested for agrifood applications, focusing on the detection of thiram pesticide. The system achieved a detection limit of 0.24 ppm (1 µM), meeting the sensitivity requirements for regulatory compliance in food safety. A strong linear correlation (R2 ≈ 0.99) was observed between the SERS peak intensity at 1370 cm−1 and thiram concentrations, underscoring its potential for quantitative analysis. The combination of high sensitivity, reproducibility, and environmental sustainability makes the AuNPs@BC platform a promising solution for developing cost-effective, flexible, and portable sensors for pesticide monitoring and other biosensing applications.

Development of High Surface Area Organosilicate Nanoparticulate Thin Films for Use in Sensing Hydrophobic Compounds in Sediment and Water.

The scope of this study was to apply advances in materials science, specifically the use of organosilicate nanoparticles as a high surface area platform for passive sampling of chemicals or pre-concentration for active sensing in multiple-phase complex environmental media. We have developed a novel nanoporous organosilicate (NPO) film as an extraction phase and proof of concept for application in adsorbing hydrophobic compounds in water and sediment. We characterized the NPO film properties and provided optimization for synthesis and coatings in order to apply the technology in environmental media. NPO films in this study had a very high surface area, up to 1325 m2/g due to the high level of mesoporosity in the film. The potential application of the NPO film as a sorbent phase for sensors or passive samplers was evaluated using a model hydrophobic chemical, polychlorinated biphenyls (PCB), in water and sediment. Sorption of PCB to this porous high surface area nanoparticle platform was highly correlated with the bioavailable fraction of PCB measured using whole sediment chemistry, porewater chemistry determined by solid-phase microextraction fiber methods, and the Lumbriculus variegatus bioaccumulation bioassay. The surface-modified NPO films in this study were found to highly sorb chemicals with a log octanol-water partition coefficient (Kow) greater than four; however, surface modification of these particles would be required for application to other chemicals.

PVA-TiO2 Nanocomposite Hydrogel as Immobilization Carrier for Gas-to-Liquid Wastewater Treatment

This study investigates the development of polyvinyl alcohol (PVA) gel matrices for biomass immobilization in wastewater treatment. The PVA hydrogels were prepared through a freezing–thawing (F-T) cross-linking process and reinforced with high surface area nanoparticles to improve their mechanical stability and porosity. The PVA/nanocomposite hydrogels were prepared using two different nanoparticle materials: iron oxide (Fe3O2) and titanium oxide (TiO2). The effects of the metal oxide nanoparticle type and content on the pore structure, hydrogel bonding, and mechanical and viscoelastic properties of the cross-linked hydrogel composites were investigated. The most durable PVA/nanoparticles matrix was then tested in the bioreactor for the biological treatment of wastewater. Morphological analysis showed that the reinforcement of PVA gel with Fe2O3 and TiO2 nanoparticles resulted in a compact nanocomposite hydrogel with regular pore distribution. The FTIR analysis highlighted the formation of bonds between nanoparticles and hydrogel, which caused more interaction within the polymeric matrix. Furthermore, the mechanical strength and Young’s modulus of the hydrogel composites were found to depend on the type and content of the nanoparticles. The most remarkable improvement in the mechanical strength of the PVA/nanoparticles composites was obtained by incorporating 0.1 wt% TiO2 and 1.0 wt% Fe2O3 nanoparticles. However, TiO2 showed more influence on the mechanical strength, with more than 900% improvement in Young’s modulus for TiO2-reinforced PVA hydrogel. Furthermore, incorporating TiO2 nanoparticles enhanced hydrogel stability but did not affect the biodegradation of organic pollutants in wastewater. These results suggest that the PVA-TiO2 hydrogel has the potential to be used as an effective carrier for biomass immobilization and wastewater treatment.

Flexible and free-supporting Prussian blue analogs /MXene film for high-performance sodium-ion batteries

Sodium-ion batteries are the most promising alternative to lithium-ion batteries because of their low cost and environmental friendliness. Prussian blue analogs (PBAs) have attracted the attention of researchers because of their open skeleton structure and abundant redox active sites. However, the interstitial water in its crystal structure and poor electron conductivity limit its performance in sodium-ion batteries. A flexible self-supporting electrode is prepared by anhydrous preparation in a ball mill and simple filtration method. The high surface area nanoparticles and the high flexibility MXene layer in the electrode adapt to the rapid Na+ dynamics, alleviating the electrode expansion. The formation of a NaF-rich cathode-electrolyte interface (CEI) layer on the electrode surface inhibits the erosion of active substances by electrolyte, reduces the capacity attenuation of the electrode, and enhances the cyclic stability of the electrode. Electrode without a conductive agent and binder shows excellent electrochemical performance. The discharge capacity of the electrode is 58.3 mAh g−1at 1000 mA g−1 current density, and the capacity retention rate is 59.7% after 1000 cycles. This work has implications for the design of the next generation of low-cost, flexible, and fast charge and discharge energy storage devices.

Remediation of Water Using a Nanofabricated Cellulose Membrane Embedded with Silver Nanoparticles.

The removal of pesticide pollution is imperative, because of their high environmental load and persistence, and their potential for bioaccumulation in, and toxicity to the environment. Most pesticides are found to be toxic even at trace levels. AgNPs can be effectively used for the adsorption of pesticides, and the incorporation of the AgNPs onto a support polymeric membrane enhances their effectiveness and reduces the potential unwanted consequences of intentionally adding free nanoparticles to the environment. Here, silver nanoparticles (AgNPs) were synthesized using a reliable, eco-friendly, and one-step "green" method, by reacting Mentha Piperita (mint) extract with AgNO3 aqueous solution at 60 °C in a microwave. The resulting high surface area nanoparticles are both economic and effective environmental remediation agents, playing a promising role in the elimination of aquatic pesticide pollution. Embedding the nanoparticles into a cellulose membrane at a low concentration (0.1 g) of AgNPs was shown to result in effectively adsorption of representative pesticides (Cypermethrin, Paraquat, and Cartap) within 60 min, while increasing the concentration of nanoparticles incorporated into the membrane further enhanced the removal of the exemplar pesticides from water. The high adsorption capacity makes the cellulose-AgNPs membrane an excellent substrate for the remediation of pesticide-polluted water.

Two Routes for Sonochemical Synthesis of Pt-Nanoparticles

To improve the performance of electrochemical hydrogen conversion devices such as electrolyzers and fuel cells, more efficient catalyst materials must be developed. As the available surface area is key to the performance of a catalyst, high surface area nanoparticles are required. The synthesis of such nanostructured catalysts is predominantly based on chemical reduction with a strong reducing agent like sodium borohydride. However, it is difficult to achieve the desired particle properties without the use of additives such as surfactants or stabilizers.In order to achieve more control over the nucleation and growth stage of the nanoparticles, we can replace the chemical reduction route by sonochemical reduction. In sonochemistry, high power ultrasound is used to generate reducing radicals which allow for controlled reduction of metal precursors. The radical generation rate is strongly linked to the nucleation and growth of the resulting nanoparticles and can easily be tuned by adjusting the ultrasonic frequency and power. Ultrasound therefore offers an easy and reproducible way of tuning the size of nanoparticles.In our work we have compared the size, shape, and morphology of Pt-nanoparticles synthesized sonochemically and with chemical reduction to see if the sonochemical route indeed offers better control during nucleation and growth. TEM-images along with X-ray diffractograms revealed that the sonochemical route gives smaller and more monodisperse particles compared to chemical reduction. In addition, the particle shape was found to be spherical with the sonochemical route, whereas chemical reduction resulted in many different shapes. The better and easier control over synthesis parameters exhibited by the sonochemical route can therefore be utilized to produce nanoparticles of very similar physical properties. We also showed that the catalytic properties of these nanoparticles towards hydrogen evolution were very similar further strengthening the sonochemical route when it comes to development of catalyst materials.A comparison between high frequency (408 kHz) and low frequency (20 kHz) ultrasound was also made to determine the impact of the higher mechanical effects expected at lower frequencies. No significant differences in particle size and morphology were found, but agglomerate sizes were found to decrease at lower frequencies. In addition, it was found that extensive probe erosion occurs at 20 kHz resulting in contamination of the nanoparticle solution. In fact, it was shown that the eroded particles act as nucleation sites for Pt-nanoparticles and increased reduction rates were observed. No such particle erosion happened at higher frequencies which led us to conclude that direct sonication at low ultrasonic frequencies in general must be avoided to prevent contamination of your system. This is important in all applications of low frequency (20 kHz) ultrasound, whether it be sonochemistry, dispersion of colloids, or ink preparation for electrochemical characterization.

ScOx rich surface terminations on lanthanide scandate nanoparticles

The lanthanide scandate materials are widely used substrates for thin film growth and the potential applications of the $Ln{\mathrm{ScO}}_{3}$ materials continue to grow with the recent ability to synthesize them as cuboidal faceted nanoparticles. A comprehensive understanding of the surface structure and chemistry of these oxides is essential for their informed application, either as single crystal or high surface area nanoparticle substrates. Here the ${100}$ pseudocubic surfaces of $Ln{\mathrm{ScO}}_{3}$ ($Ln=\mathrm{La}$, Nd, Sm, Gd) nanoparticles were examined with aberration-corrected electron microscopy and higher-level density functional theory to reveal ${\mathrm{ScO}}_{x}$ rich terminations across all investigated surfaces. Mixed terminations of single and double layer nature were observed, indicating the presence of multiple domains at the surface and introducing the possibility of synthetically controlling the surface reconstruction in the future.

Azo(xy) vs Aniline Selectivity in Catalytic Nitroarene Reduction by Intermetallics: Experiments and Simulations

Intermetallic nanoparticles are promising catalysts in hydrogenation and fuel cell technologies. Much is known about the ability of intermetallic nanoparticles to selectively reduce nitro vs alkene, alcohol, or halide functional groups; less is known about their selectivity toward aniline vs azo or azoxy condensation products that result from the reduction of a nitro group alone. Because azo(xy)arenes bear promise as dyes, chemical stabilizers, and building blocks to functional materials but can be difficult to isolate, developing high surface area nanoparticle catalysts that display azo(xy) selectivity is desirable. To address this question, we studied a family of nanocrystalline group 10 metal (Pd, Pt)- and group 14 metal (Ge, Sn, Pb)-containing intermetallics─Pd2Ge, Pd2Sn, Pd3Sn2, Pd3Pb, and PtSn─in the catalytic reduction of nitroarenes. In contrast to monometallic Au, Pt, and Pd nanoparticles and ″random″ PdxSn1 – x nanoalloys, which are selective for aniline, nanoparticles of atomically precise intermetallic Pd2Ge, Pd2Sn, Pd3Sn2, and PtSn prefer an indirect condensation pathway and have a high selectivity for the azo(xy) products. The only exception is Pd3Pb, the most active among the intermetallic nanoparticles studied here, which is instead selective for aniline. Employing a novel application of molecular dynamics─based on machine learned potentials within a DeePMD framework─to heterogeneous catalysis, we are able to identify key reaction species on the different types of catalysts employed, furthering our understanding of the unique selectivity of these materials. By demonstrating how intermetallic nanoparticles can be as active yet more selective than other more traditional catalysts, this work provides new physical insights and opens new opportunities in the use of these materials in other important chemical transformations and applications.

Synthesis of high surface area and plate-like Magnesium Oxide nanoparticles by pH-controlled precipitation method

Synthesis of high surface area and plate-like Magnesium Oxide nanoparticles by pH-controlled precipitation method

Co9S8 nanoparticles embedded in nitrogen, sulfur codoped porous carbon nanosheets for efficient oxygen/hydrogen electrocatalysis

Directly pyrolyzing organometal complex represents a judicious strategy to fabricate efficient multifunctional carbon-based electrocatalysts, but the structure/composition of the catalysts is commonly complicated and the corresponding electrocatalytic activities are usually compromised. In this study, we report a selective leaching route to prepare small Co9S8 nanoparticles supported on nitrogen, sulfur codoped porous carbon nanosheets (Co9S8@PNSC) by pyrolyzing sheet-like Co(II)-coordinated thiourea-ethylenediamine-formaldehyde resin (Co-TEFR)/polydopamine (PDA) hybrids that are covered by silica shell layer, followed by removal of the silica and Co nanoparticles with NH4HF2 through a wet etching method. Consequently, the resultant Co9S8@PNSC exhibits high specific surface area, hierarchical porosity and tiny Co9S8 nanoparticles, which are conducive to the maximal utilization of active sites, endowing remarkable oxygen electrocatalysis with a half-wave potential of +0.845 V for oxygen reduction reaction and a low overpotential of 314 mV at current density of 10 mA cm−2 for oxygen evolution reaction. Besides, such composite also shows a considerable electrocatalytic performance for hydrogen generation. When applied in an assembled zinc-air battery, Co9S8@PNSC displays a high power-density (203 mW cm−2) and favorable cycling lifespan. The results from the present strategy may provide an exemplification in rational design and fabrication of carbon-based nanocomposite for high-performance multifunctional electrocatalysis.

High Performance Commercial SOFC Cathodes Achieved with YSZ Nanoparticles

The electrochemical performance of solid oxide fuel cell (SOFC) cathodes was improved via integration of ultra-high surface area ceramic nanoparticles, up to 115 m2·g-1, generated with a novel processing method herein introduced. The processing method generates the high surface area nanoparticles at traditional SOFC sintering temperatures in two steps. In the first step, a hybrid inorganic-organic material comprising the ceramic precursors is sintered in an inert atmosphere at any temperature between 850°C-1350°C. During this step, an amorphous carbon template is generated in situ, preventing coarsening of the ceramic nanoparticles. The carbon template is then removed during the second step by a mild calcination in air at 700°C. Yttria-stabilized zirconia (YSZ), lanthanum strontium cobalt ferrite (LSCF), gadolinium-doped ceria (GDC), and strontium titanate (STO) have all been successfully prepared by this method. YSZ nanoparticles (nYSZ) were incorporated into a lanthanum strontium manganite-YSZ (LSM-YSZ) cathode of a commercial cell, resulting in a 90% increase in maximum power density. Impedance spectroscopy indicates the large improvement in power density was attributed to a combination of significant improvement in polarization resistance, a 45% decrease, and ohmic resistance, a 35% decrease. Remarkably, the performance of the cell modified with nYSZ was higher than cells modified with two mixed ionic electronic conductors (MIEC): PrxBa1-xCo3-δ (PBC) and LaxSr1-xCoyFe1-yO3-δ (LSCF). Both MIECs enhanced the density of active sites, but, unlike nYSZ, did not significantly improve ohmic resistance. The results demonstrate a novel pathway to achieve high performance in commercial SOFCs.

Cube Fe3O4 nanoparticles embedded in three-dimensional net porous carbon from silicon oxycarbide for high performance supercapacitor

Transition metal oxide and porous carbon both with unique structure are hopeful for employing high-performance energy storage devices. In our work, a simple and inexpensive chemical precipitation method was utilized to obtain the ferroferric oxide/carbide-derived carbon (Fe3O4/CDC) composite electrode of supercapacitor. The Fe3O4 nanoparticles with cube shape were embedded in three-dimensional net porous CDC material. Owing to the superior synergistic effect between CDC with high specific surface area and Fe3O4 nanoparticles with high redox activity, the optimal Fe3O4/CDC composite electrode shows good capacitive performances. In the three-electrode system, the Fe3O4/CDC composite electrode exhibits high specific capacitance in neutral Na2SO4 (293.7 F g−1) and alkaline KOH electrolytes (346.5 F g−1) at 1 A g−1. Especially, the Fe3O4/CDC composite shows better electrochemical stability in Na2SO4 electrolyte. The symmetrical supercapacitor was produced by using Na2SO4 as electrolyte and Fe3O4/CDC composite as electrode. The as-produced device offers an excellent energy density of 14.3 Wh kg−1 at 4093 W kg−1. After 4000 cycles, 92.3% of the initial specific capacitance can be retained, proving the remarkable cycle stability. Thus, the effective and facile combination of three-dimensional net porous CDC and Fe3O4 nanoparticles to obtaining electrode material is a promising strategy for efficient energy-storage application.

Effect of undercoordinated Ag(111) defect sites on the adsorption of ethanol

In recent years, the use of silver-based materials for selective and highly active ethanol reactivity in single atom catalysis and the ethanol oxidation reaction in direct fuel cells highlights the importance of silver (Ag) in an ethanol economy. Understanding the interaction of ethanol with Ag(111) and the natural defects found on extended Ag(111) is critical to the overall understanding of more complex catalytic processes including ethanol activation over Ag-based catalysts. The research herein aims to characterize the interaction of ethanol molecules on undercoordinated defect sites of Ag(111) to mimic active sites found on Ag nanoparticle catalysts. The interaction between ethanol and Ag(111) was studied using temperature programed desorption (TPD), x-ray photoelectron spectroscopy, and density functional theory (DFT). Molecular ethanol adsorption and desorption from Ag(111) and the distinction between undercoordinated Ag(111) adsorption sites were determined using TPD in correlation with DFT. Complete analysis of TPD data for ethanol adsorbed to terrace sites was used to calculate a kinetic prefactor (3.4 × 1015) and desorption energy (0.54 eV). A better understanding of defect-dependent behavior for ethanol on silver can lead to a greater insight into high surface area nanoparticle catalysts used in industries, catalytic converters, and photo-, electro-, and heterogeneous catalysis. The results suggest that ethanol preferentially adsorbs to undercoordinated sites on Ag(111), resulting in higher binding energies for these molecules (Redhead first order approximation for desorption energies is terrace, 0.54 eV; step edge, 0.57 eV; and kink sites, 0.61 eV). Furthermore, alteration of the silver surface can lead to a redistribution of these sites.

In Situ Resistance Monitoring during Flame-Aerosol Deposition of Metal Oxide Gas Sensing Layers

Introduction Chemo-resistive sensors are highly promising for the detection of trace-level compounds in medical diagnostics[1] or indoor air monitoring[2]. In particular, gas sensors made by direct flame-aerosol synthesis are attractive due to their highly porous and crack-free sensing films[3]. They are composed of high-surface area nanoparticles with diverse composition tuned for ppb-level sensitivity and high selectivity towards key analytes such as Si-doped WO3 for acetone[1] or Ti-doped ZnO for isoprene[4]. Fabrication development has also led to the ability to process flame-made sensors by techniques compatible with standard silicon-wafer micromachining[5]. This enables the preparation of low power sensors that are attractive for portable handheld devices. So far, the development of such sensors has been focused mostly on material composition and, to a lesser extent, on film morphology and design. However, optimizing the latter could improve the sensor sensitivity as well as response and recovery times. Measuring the resistance during flame-deposition of nanostructured films in situ offers fabrication control by providing immediate feedback when an interconnected film is created[6]. This ultimately allows the fabrication of sensing films of minimal thickness and optimal resistance in a reproducible and economical manner. In situ resistance monitoring This work focuses on in situ monitoring the resistance of nanostructured films fabricated by direct deposition of flame-made Sb-doped SnO2 nanoparticles[6]. The sensing film morphology was tuned by a substrate-impinging particle flame, fed by a precursor solution containing varying metal ion concentrations. In situ resistance monitoring enabled control over final film resistance as well as direct insight into network formation and nanoparticle growth, necking and coalescence. The performance of these films as ethanol vapor sensors was assessed and related to their in situ resistance and nanoparticle film characteristics. Method Gas sensing nanoparticle films were prepared by direct deposition of flame-made Sb-doped (12 at%) SnO2 onto alumina substrates with interdigitated platinum electrodes. Deposition was carried-out for up to 6 min. Substrate preheating, film deposition and cooling to room temperature was closely monitored by the in situ resistance (Ri) between the interdigitated electrodes with a multimeter (Tektronix DMM4050). Nanoparticle sensing films were imaged by scanning electron microscopy (Hitachi S-4800 FE-SEM) after particle deposition for 2 min. Results and Conclusions Figure 1a shows the formation of Sb-doped SnO2 nanoparticles in a flame, followed by direct deposition onto the sensor substrate and in situ film resistance (Ri) read out. Figure 1b shows the in situ film resistance as a function of deposition duration using 1 (red squares), 10 (blue circles) or 100 (green triangles) mM FSP precursor solution concentrations (PSC). At low PSC (1 mM), the Ri remains at first (up to ca. 1 min) rather indifferent to nanoparticle deposition as it takes some time to build the interconnected particle bridges. But as deposition is prolonged (t >1.5 min), the Ri starts to drop. This clearly indicates the formation of an interconnected network of nanoparticles. Also quite notable is the strong oscillation of Ri by more than an order of magnitude during network formation. This stems from the constant formation (by deposition) and break-up of necked nanoparticles (by coalescence) on the substrate (i.e., repeatedly from lace-like to cauliflower-like structures) during flame-deposition. Increasing the PSC from 1 to 10 mM or 100 mM leads naturally to a higher generation rate of nanoparticles and, therefore, faster drop in resistance. This is confirmed by SEM imaging after 2 minute deposition time for 1, 10 and 100 mM (Figure 2 a-c). As expected, nanoparticles are assembled more densely at higher PSC. As a result, the film formation and morphology of Sb-doped SnO2 can be monitored during direct flame-deposition. This monitored Ri is correlated to its evolving particle size and necking, enabling the ability to optimize material quantity, fabrication time and the final film resistance. This leads to the ability to rapidly synthesize thin flame-made gas sensors with improved sensitivity and reduced response/recovery times.

Synthesis and characterization of meso-porous Au-modified SnO2 fibers using natural silk with enhanced sensitivity for n-butanol

Meso-porous SnO2 fibers were prepared via hydrothermal method, and natural silk was used as bio-template. Au nanoparticles served as the sensitizer were prepared on the surface of these SnO2 fibers to further enhance the properties of gas sensing. Results show that these Au-modified products presented high surface area of 168.66 m2/g and meso-porous structure, and these fibers were composed of nanosized SnO2 and Au particles with the size of about 7 ± 0.5 nm and 5 ± 0.5 nm, respectively. Gas sensing properties of these synthesized pristine products and Au-loaded fibers were investigated. Results show that these Au-modified SnO2 fibers exhibited remarkably enhanced sensing performance to n-butanol with high response, good selectivity and good stability. The gas sensing mechanism was discussed from the effects of meso-porous structure, high surface area and Au nanoparticle catalytic activity.

Anthracene removal from water samples using a composite based on metal-organic-frameworks (MIL-101) and magnetic nanoparticles (Fe3O4)

Polycyclic hydrocarbons constitute an important source of very dangerous pollutants. Different materials have been used as adsorbent for their removal, but they present difficulties in the separation process. The use of a material based on metal-organic framework (MOF) with large pores and high surface area and magnetic nanoparticles with superparamagnetic properties is an interesting strategy. In this work a magnetic composite based on MOF (MIL-101) and Fe3O4 magnetic nanoparticles (Fe3O4/MIL-101) was obtained by a simple synthesis method and used as adsorbent for the removal of anthracene. The composite was characterized by transmission electron microscopy, x-ray powder diffraction and vibrating sample magnetometer. The results showed that kinetic data followed a first-order model and equilibrium data were well fitted by the Langmuir model. The maximum adsorption capacity was 12.7 mg g−1 at pH 6 in 60 min of exposure. The composite was applied for the adsorption of anthracene in water samples reaching more than 95% of anthracene removal in 1 h of contact. The composite material was effectively separated using an external magnet, and no further centrifugation or filtration processes were needed. This composite is a great alternative to remove polycyclic hydrocarbons from water samples and has potential to extend to the removal of other contaminants.

PEGylated nano-graphene oxide as a nanocarrier for delivering mixed anticancer drugs to improve anticancer activity

Due to their high specific surface area, graphene oxide and graphene oxide-base nanoparticles have great potential both in dual-drug delivery and combination chemotherapy. Herein, we developed cisplatin (Pt) and doxorubicin (DOX) dual-drug-loaded PEGylated nano-graphene oxide (pGO) to facilitate combined chemotherapy in one system. In this study, nano-sized pGO-Pt/DOX ranged around 161.50 nm was fabricated and characterized using zeta-potential, AFM, TEM, Raman, UV-Vis, and FTIR analyses. The drug delivery efficacy of Pt was enhanced through the introduction of pGO, and the final weight ratio of DOX: Pt: pGO was optimized to 0.376: 0.376: 1. In vitro studies revealed that pGO-Pt/DOX nanoparticles could be effectively delivered into tumor cells, in which they induced prominent cell apoptosis and necrosis and exhibited higher growth inhibition than the single drug delivery system or free drugs. The pGO-Pt/DOX induced the most prominent cancer cell apoptosis and necrosis rate with 18.6%, which was observed almost 2 times higher than that of pGO-Pt or pGO-DOX groups. in the apoptosis and necrotic quadrants In vivo data confirmed that the pGO-Pt/DOX dual-drug delivery system attenuated the toxicity of Pt and DOX to normal organs compared to free drugs. The tumor inhibition data, histopathology observations, and immunohistochemical staining confirmed that the dual-drug delivery system presented a better anticancer effect than free drugs. These results clearly indicated that the pGO-Pt/DOX dual-drug delivery system provided the means for combination drug delivery in cancer treatment.

Effects of Formulated Nano-Urea Hydroxyapatite Slow Release Fertilizer Composite on the Physical, Chemical Properties, Growth and Yield of Cyamopsis tetragonoloba (Cluster Beans)

Urea and phosphorous fertilizers are commonly used in agriculture but, due to their solubility in water and transportation, cause eutrophication. Hence, it is thought worthwhile to investigate for urea hydroxyapatite nanoparticles which have less mobility and could supply required N and P macronutrients to the crops. These high surface area nanoparticles are synthesized through chemical co-precipitation method and it is assumed that due to their biocompatibility, act as rich phosphorous and nitrogen source. These are characterized by powder X-ray diffraction (PXRD), dynamic light scattering (DLS), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared (FT-IR). The impact of urea hydroxyapatite nanofertilizer on growth and yield of cluster bean plants for the period of four months has been carried out. The experimental results have shown that the usage of these nanofertilizers have enhanced both the plant growth and yield. The application of urea hydroxyapatite nanocomposites for the bio-availability of plants considered to be environment friendly.

Facile synthesis of novel microporous CdSe/SiO2 nanocomposites selective for removal of methylene blue dye by tandem adsorption and photocatalytic process

CdSe is considered a promising photocatalyst that exhibits a lower band gap energy (1.7 eV). However, the high cost of its metal precursors, low surface area and the rapid electron–hole recombination are the main problems that limit its industrialization. In this research work, incorporation of various proportions of CdSe (0–10 wt%) on the surface of microporous silica (432 m2/g) were carried out through ultrasonic route to enhance the chemical interaction between the synthesized nanoparticles and the support. X-ray diffraction (XRD), N2-adsorption–desorption isotherm, diffuse reflectance spectra, photoluminescence, field emission scanning electron microscope and high resolution transmission electron microscope (HRTEM) were carried out to investigate the physicochemical properties of the novel nanocomposites. HRTEM and XRD analysis indicate the homogeneous dispersion of CdSe nanoparticles of crystallite size (8–19) nm on silica surface. The influence of varying the concentration of CdSe on its degree of dispersion on silica via the hydroxyl group that dispersed on silica negatively charged surface was monitored. The experimental results have pointed out that the nominal value required for spreading CdSe as monolayer on silica surface is 3.25 molecules of CdSe per 100 A2 of silica that is considered the most reactive photocatalyst in removal of MB dye. Below this nominal value, the amount of CdSe dispersed on silica is not enough to produce the required number of reactive radicals responsible for dye degradation. However, above the nominal value, the aggregation of CdSe layers on silica surface prevent the light penetration and induce electron–hole centers that reduce the lifetime of the photocatalyst. The removal of methylene blue dye via tandem adsorption and photocatalytic route increases with increasing CdSe concentration up to 10 wt% that is responsible for removal 90% of MB dye followed by reducing the reactivity for the sample containing 15 wt% CdSe. A direct relationship between adsorption and the photocatalytic reactivity is purposed assuming that the photocatalytic process require adsorption on high surface area nanoparticles as prime key step in increasing the contact probability between the photocatalyst and the organic dye that facilitate the production of large number of reactive radicals available for dye mineralization. TOC and COD analysis confirmed the complete mineralization of MB dye. The scavenger results indicate that both positive hole and hydroxyl radicals are the predominant reactive species for degradation of MB dye over CdSe and CdSe10. The achievement of controlling the dispersion of metal selenide on a support using ultrasonic route would certainly open a new approach for catalysis preparation.

Ultrasensitive immunosensor for acrylamide based on chitosan/SnO2-SiC hollow sphere nanochains/gold nanomaterial as signal amplification

An electrochemical immunosensor for ultrasensitive detection of acrylamide (AA) in water and food samples was developed. SnO2-SiC hollow sphere nanochains with high surface area and gold nanoparticles with good electroconductivity were fabricated onto the surface of a glassy carbon electrode pre-coated with chitosan. The coating antigen (AA-4-mercaptophenylacetic acid-ovalbumin conjugate, AA-4-MPA-OVA) was immobilized on the electrode. Polyclonal antibody specific for AA-4-MPA was conjugated to gold nanorod (AuNR) as primary antibody (AuNR-Ab1). Horseradish peroxidase labelled anti-rabbit antibody produced in goat was conjugated to AuNR as secondary antibody (HRP-AuNR-Ab2). For detection, the analyte (AA-4-MPA) in sample competed with coating antigen for binding with AuNR-Ab1. After washing, HRP-AuNR-Ab2 was added to capture the AuNR-Ab1, and the electrical signal was obtained by addition of hydroquinone and H2O2. After investigation of the binding ability on nanomaterials and optimization of competitive immunoassay conditions, the proposed immunosensor exhibited a sensitive response to AA with a detection limit of 45.9 ± 2.7 ng kg−1, and working range of 187 ± 12.3 ng kg−1 to 104 ± 8.2 μg kg−1 for drinking water samples. Recoveries of AA from spiked samples were ranged from 86.0% to 115.0%. The specificity, repeatability and stability of the immunosensor were also proved to be acceptable, indicating its potential application in AA monitoring.