Surface Modification Of NPs Research Articles

Sensitive Colorimetric Lateral Flow Assays Enabled by Platinum-Group Metal Nanoparticles with Peroxidase-Like Activities.

The last several decades have witnessed the success and popularity of colorimetric lateral flow assay (CLFA) in point-of-care testing. Driven by increasing demand, great efforts have been directed toward enhancing the detection sensitivity of CLFA. Recently, platinum-group metal nanoparticles (PGM NPs) with peroxidase-like activities have emerged as a type of promising colorimetric labels for enhancing the sensitivity of CLFA. By incorporating a simple and rapid post-treatment process, the PGM NP-based CLFAs are orders of magnitude more sensitive than conventional gold nanoparticle-based CLFAs. In this perspective, the study begins with introducing the design, synthesis, and characterization of PGM NPs with peroxidase-like activities. The current techniques for surface modification of PGM NPs are then discussed, followed by operation and optimization of PGM NP-based CLFAs. Afterward, opinions are provided on the social impact of PGM NP-based CLFAs. Lastly, this perspective is concluded with an outlook of future research directions in this emerging field, where the challenges and opportunities are discussed.

Synthesis and Superficial Modification "In Situ" of Copper Selenide (Cu2-x Se) Nanoparticles and Their Antibacterial Activity.

Copper selenide nanoparticles (Cu2-x Se NPs) have received a lot of attention in recent decades due to their interesting properties and potential applications in various areas such as electronics, health, solar cells, etc. In this study, details of the synthesis and characterization of copper selenide nanoparticles modified with gum arabic (GA) are reported. Also, through transmission electronic microscopy (TEM) analysis, the transformation of the morphology and particle size of copper selenide nanoparticles in aqueous solution was studied. In addition, we present an antimicrobial study with different microorganisms such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Candida albiacans (C. albicans). Copper selenide nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry analysis (DSC) and TEM. XRD confirmed the crystal-line structure of the nanoparticles such as cubic berzelanite with a particle size of 6 nm ± 0.5. FTIR and TGA corroborated the surface modification of copper selenide nanoparticles with gum arabic, and DSC suggested a change in the structural phase from cubic to hexagonal. TEM analysis demonstrated that the surface modification of the Cu2-x Se NPs stabilized the nanostructure of the particles, preventing changes in the morphology and particle size. The antimicrobial susceptibility analysis of copper selenide nanoparticles indicated that they have the ability to inhibit the microbial growth of Staphylococcus aureus, Escherichia coli and Candida albicans.

Fabrication and characterization of PMMA denture base nanocomposite reinforced with hydroxyapatite and multi-walled carbon nanotubes

Polymethyl Methacrylate (PMMA) is still one of the most popular denture base materials in dentistry due to its superior mechanical properties. However, its long-term use can result in defects such as low flexural strength and brittleness, which can be addressed by strengthening its mechanical properties. In this study, the effect of adding non-modified and modified hydroxyapatite nanoparticles (HaP NPs) and multi-walled carbon nanotubes (MWCNTs) on the thermal and mechanical properties of PMMA denture base materials was investigated. First, the modified HaP (MHaP) NPs and modified MWCNTs (MMWCNTs) were prepared by a vinyltriethoxysilane (VTES) agent. Then, two-component PMMA-HaP/MHaP and PMMA-MWCNT/MMWCNT, and three-component PMMA-HaP/MHaP-MWCNT/MMWCNT composite samples were fabricated from commercial dental heat-curing acrylic resin (Acrosun) with different amounts of HaP/MHaP (3, 5, and 10 wt%) and MWCNT/MMWCNT (0.25, 0.5, and 1 wt%). The samples were investigated by Simultaneous Thermal Analysis (STA), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray Spectroscopy (EDS), Dynamic Mechanical Analysis (DMA), and Three-point flexural test. It was observed that surface modification of NPs improved the interaction of NPs and polymer chains in the matrix and resulted in better mechanical properties of nanocomposites. In the sample containing 3 wt% MHaP and 0.25 wt% MMWCNT, the flexural strength and flexural modulus were increased by 45 % and 42 % compared to the control sample, respectively, and the glass transition temperature (Tg) based on the DMA test was 152.7 °C, which was higher than in the other samples. The results of MTT assay studies indicated that adding MHaP and MMWCNT enhanced cell viability. In the PMMA- 3 wt% MHaP- 0.25 wt% MMWCNT composite, the cell viability was increased to 153.75 ± 9.7 % and confirmed its biocompatibility properties.

Synthesis and characterization of TiO2 nanoparticles combined with geraniol and their synergistic antibacterial activity

BackgroundThe emergence of antibiotic resistance in pathogenic bacteria has become a global threat, encouraging the adoption of efficient and effective alternatives to conventional antibiotics and promoting their use as replacements. Titanium dioxide nanoparticles (TiO2 NPs) have been reported to exhibit antibacterial properties. In this study, we synthesized and characterized TiO2 NPs in anatase and rutile forms with surface modification by geraniol (GER).ResultsThe crystallinity and morphology of modified TiO2 NPs were analyzed by UV/Vis spectrophotometry, X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) with elemental mapping (EDS). The antimicrobial activity of TiO2 NPs with geraniol was assessed against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli. The minimum inhibitory concentration (MIC) values of modified NPs ranged from 0.25 to 1.0 mg/ml against all bacterial strains, and the live dead assay and fractional inhibitory concentration (FIC) supported the antibacterial properties of TiO2 NPs with GER. Moreover, TiO2 NPs with GER also showed a significant decrease in the biofilm thickness of MRSA.ConclusionsOur results suggest that TiO2 NPs with GER offer a promising alternative to antibiotics, particularly for controlling antibiotic-resistant strains. The surface modification of TiO2 NPs by geraniol resulted in enhanced antibacterial properties against multiple bacterial strains, including antibiotic-resistant MRSA. The potential applications of modified TiO2 NPs in the biomedical and environmental fields warrant further investigation.

Toxicity of Silver Nanoparticles Supported by Surface-Modified Zirconium Dioxide with Dihydroquercetin.

The antibacterial performance and cytotoxic examination of in situ prepared silver nanoparticles (Ag NPs), on inorganic-organic hybrid nanopowder consisting of zirconium dioxide nanoparticles (ZrO2 NPs) and dihydroquercetin (DHQ), was performed against Gram (−) bacteria Escherichia coli and Gram (+) bacteria Staphylococcus aureus, as well as against human cervical cancer cells HeLa and healthy MRC-5 human cells. The surface modification of ZrO2 NPs, synthesized by the sol-gel method, with DHQ leads to the interfacial charge transfer (ICT) complex formation indicated by the appearance of absorption in the visible spectral range. The prepared samples were thoroughly characterized (TEM, XRD, reflection spectroscopy), and, in addition, the spectroscopic observations are supported by the density functional theory (DFT) calculations using a cluster model. The concentration- and time-dependent antibacterial tests indicated a complete reduction of bacterial species, E. coli and S. aureus, for all investigated concentrations of silver (0.10, 0.25, and 0.50 mg/mL) after 24 h of contact. On the other side, the functionalized ZrO2 NPs with DHQ, before and after deposition of Ag NPs, do not display a significant decrease in the viability of HeLa MRC-5 cells in any of the used concentrations compared to the control.

Facile functionalization of YVO4:Eu3+: From nanoparticles to luminescent PMMA nanocomposites for radiation detectors

YVO4:Eu3+ is a luminescent material that has been widely used in cathode ray tubes and plasma display panels. Nowadays, different applications are being explored. Fiber-optic Dosimetry (FOD) is an alternative to traditional dosimetry systems for radiotherapy treatments. Although some published results have demonstrated the potential of using YVO4:Eu3+ as nanometer powder for FOD systems, none of them tend to improve its tissue equivalence, a significant limitation. One possible solution could be to disperse the NPs in a tissue-equivalent polymer matrix, like Poly Methyl Methacrylate (PMMA). Consequently, YVO4:Eu3+/PMMA nanocomposites were developed using NPs synthesized according to a combustion method previously reported. This work focuses on studying two different NPs functionalization strategies. One of them involves the synthesis of a SiO2 shell and a posterior treatment with Oleic Acid (OA). The other involves the use of a silane (3-(Trimethoxysilyl)propyl methacrylate, TMSPM) as a coupling agent. Both strategies allow the surface modification of NPs. The study of luminescence properties of NPs showed no significant changes between both functionalized NPs related to Eu3+ spectrum characteristic peaks. However, YVO4:Eu3+@TMSPM has better performance (the reduction in YVO4:Eu3+@TMSPM is about 15%, while in YVO4:Eu3+@SiO2@OA is 62%). On the other hand, functionalized nanoparticles were used to develop polymeric nanocomposites (PNCs) by in situ polymerization of Methyl Methacrylate using a cyclic triperoxide as initiator. Functionalized NPs were characterized by Fourier Transform Infrared Spectroscopy, Transmission Electron Microscopy, Dynamic Light Scattering, Thermogravimetric Analysis, and luminescence measurements. Films were obtained by dissolution of the PNCs, and their luminescent properties were also studied. Results indicate that although the strategy that involves the silica shell plus OA is better in terms of cover density, the TMSPM promotes a better dispersion on the polymer matrix.

Ion-induced agglomeration of Ag NPs for quantitative determination of trace malachite green in natural water by SERS

This article covers a simple one-step method that has been developed for ion-induced activation/agglomeration of silver nanoparticles. While using this method in Surface-enhanced Raman spectroscopy (SERS) we have recorded high values of signal enhancement factor (EF= 3.9 ×106). An important feature of the method is high stability of analytical signal (RSD of about 2% with analyte concentration at 1 ppb). We have shown, that in case of activation of nanoparticles with chlorides of alkaline earth metals the signal amplification proceeds according to a different mechanism rather than in case of NaCl. It was found that the synergistic action of two-charged cations (Ca2+, Mg2+, Ba2+) and chloride ions leads to the agglomeration of silver nanoparticles and the formation of “hot spots”, whereas in the case of NaCl at a concentration of up to 1 mM, only the surface modification of Ag NPs occurs. Kinetic studies have been carried out, and the mechanism of this process has been proposed. The obtained data served as a basis for the development of a simple and sensitive express method for the determination of trace amounts (in the range of 0.1–10 ppb, LOD = 0.002 ppb) of malachite green in water from natural sources. In order to compensate matrix effects we applied a standard addition method which simplified considerably the sample preparation process, increased method’s accuracy and reduced the time of analysis.

One-Pot Surface Modification of β-Cu2O NPs for Biocatalytic Performance against A-549 Lung Carcinoma Cell Lines through Docking Analysis.

The physicochemical approaches and biological principles in bio-nanotechnology favor specially functionalized nanosized particles. Cuprous oxide nanoparticles (β-Cu2O NPs) of cuprite phase with a little tenorite (CuO) may be very effective in the development of novel therapeutic approaches against several fatalities including A-549 lung carcinoma cell lines. Consequently, the synthesis of β-Cu2O NPs for the improvement in the therapeutic index and drug delivery application is becoming an effective strategy in conventional anticarcinoma treatment. Hence, surface-enhanced nanosized spherical cuprous oxide nanoparticles (β-Cu2O NPs) of cuprite phase were successfully prepared using poly(ethylene glycol) (PEG) as an amphiphilic nonionic surfactant and l-ascorbic acid (K3[Cu(Cl5)]@LAA-PEG) reduced to cuprites β-Cu2O NPs via the sonochemical route. Less improved toxicity and better solubility of β-Cu2O NPs compared with Axitinib were a major reason for producing β-Cu2O NPs from K3[Cu(Cl5)]@LAA-PEG (LAA, l-ascorbic acid, PEG, poly(ethylene glycol) (PEG)). These nanoparticle syntheses have been suggested to influence their cytotoxicity, free-radical scavenging analysis, and reactive oxygen species (ROS) using poly(ethylene glycol) (PEG) and l-ascorbic acid (LAA) as coated and grafted materials due to their dose-dependent nature and IC50 calculations. The surface morphology of the formed β-Cu2O NPs has been examined via UV–vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy with energy diffraction scattering spectroscopy (SEM@EDS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analysis. X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) surface analysis results confirm the presence of pure cuprite with a very little amount of tenorite (CuO) phase, Dynamic light scattering (DLS) confirms the negative ζ-value with stable nature. Docking was performed using PDB of lung carcinomas and others, as rigid receptors, whereas the β-Cu2O NP cluster was treated as a flexible ligand.

Surface-modified ZrO2 nanoparticles with caffeic acid: Characterization and in vitro evaluation of biosafety for placental cells

The toxicity of hybrid nanoparticles, consisting of non-toxic components, zirconium dioxide nanoparticles (ZrO2 NPs), and caffeic acid (CA), was examined against four different cell lines (HTR-8 SV/Neo, JEG-3, JAR, and HeLa). Stable aqueous ZrO2 sol, synthesized by forced hydrolysis, consists of 3–4 nm in size primary particles organized in 30–60 nm in size snowflake-like particles, as determined by transmission electron microscopy and direct light scattering measurements. The surface modification of ZrO2 NPs with CA leads to the formation of an interfacial charge transfer (ICT) complex followed by the appearance of absorption in the visible spectral range. The spectroscopic observations are complemented with the density functional theory calculations using a cluster model. The ZrO2 NPs and CA are non-toxic against four different cell lines in investigated concentration range. Also, ZrO2 NPs promote the proliferation of HTR-8 SV/Neo, JAR, and HeLa cells. On the other hand, hybrid ZrO2/CA NPs induced a significant reduction of the viability of the JEG-3 cells (39 %) for the high concentration of components (1.6 mM ZrO2 and 0.4 mM CA).

Fluorescence manipulation from graphene and hydrogen-terminated graphene covered Au nanoparticles

This paper presents the fluorescence manipulation of Rhodamine-6G (R6G) due to Au nanoparticles (Au-NPs) covered by pristine graphene and hydrogen-terminated graphene. By taking florescence signals of R6G on a quartz substrate as the standard reference, we observe an ∼fourfold increase in fluorescence intensity of R6G on bare Au-NPs deposited on the quartz substrate. However, this enhancement reduces to ∼1.8-fold when Au-NPs are covered by H-terminated graphene. In the case of Au-NPs covered by pristine graphene, the fluorescence of R6G is significantly quenched by a factor of ∼7.6-fold. The resulting fluorescence level can be attributed to the local field enhancement from Au-NPs and the quenching effect of graphene in the Au–graphene hybrid nanostructure, which are confirmed by our controlled experimental and simulation results. Our work reveals that the surface modification of metal NPs by graphene materials would bring a great impact on fluorescence, providing a simple approach for artificially manipulating fluorescence for specific molecular sensing, detecting, and imaging.

Introduction of a workflow for tomographic analysis of formation stimulation using novel nano-based encapsulated acid systems

During the production time, it is crucial to manage the reservoir efficient productivity and keep it at a profitable level. Matrix acidizing in carbonate reservoirs is a common course of action to increase the efficiency of production. The present project is based on an integrated multi-disciplinary plan as an arena to merge traditional and novel technologies in the field of petroleum engineering, petroleum geoscience, chemical engineering, computer vision and mineralogy. Some crucial parameters such as permeability/porosity changes occurred during carbonate acidizing are modelled and analyzed based on various modern technologies, such as, the novel digital rock technologies. A waste variety of nanoparticles is also used in order to design a novel acid mixture for stimulating the carbonate reservoirs. Specifically, this study is considered as a one-step forward in development of smart encapsulated acid systems using a range of hydrophobic silica nanoparticles in various grades of hydrophobicity. Moreover, the present study can be considered as the first practical example for application of digital rock physics in improvement of acidizing operation in Iran and Russia. The proposed research methods are consist of preparation of encapsulated acids, sample and data collection, conventional core analysis, digital core analysis, lab experiments and modelling and conclusion. Characterization of the efficiency of this process was once more characterized using the aforementioned digital rock technologies to visualize the effect of encapsulated acid fracturing operation, impact of surface modification of silica NPs on the etching efficiency, the physical properties of core samples, and subsequently the final productivity index. Thin section, SEM and FE-SEM analysis was then performed to further evidence the efficiency of this method. Moreover, the efficiency of this method was categorized based on the identified mineralogy and rock composition. It was concluded that the dissolution rate was significantly increased as a result of acid neutralization control and the reaction rate decreased which in turn resulted in more homogenous patterns of wormholes, higher permeability, and so, more successful acid treatment. Thanks to the reduced accessible surface of acid systems caused by their emulsion-based nature, it was found that this novel encapsulation process can reduce the risks of corrosion in all the equipment in surface and bottom hole. It naturally reduces the extra costs of corrosion-related damages and subsequent workover operations, which are the common need of most of the wells treated by conventional acid fracturing operations.

Unsupported liquid-state platform for SERS-based determination of triazophos.

A highly reproducible surface-enhanced Raman scattering (SERS) unsupported liquid-state platform (ULP) was developed for accurate quantitative determination of triazophos. Herein, citrate-reduced Ag NPs suspension was concentrated and placed in a stainless steel perforated template to form the SERS ULP. The relative standard deviation of the SERS measurements was less than 5% (n ≥ 10), and the R2 of the calibration curve was 0.994. The developed SERS ULP was applied for determination of triazophos in spiked agricultural products (rice, cabbage, and apple). Experiment results showed that the coefficient of variation ranged from 5.3 to 6.2% for intra-day and from 5.5 to 6.3% for inter-day (n = 3), which proved excellent SERS reproducibility. Moreover, the results were in good agreement with those from HPLC analysis. As a liquid-state SERS substrate, the highly reproducible ULP can perform precision quantitative analysis without surface modification of NPs, which is a significant improvement. This method provides a new perspective for quantitative SERS analysis of pesticide residues. Graphical abstract.

Tuning the Surface Chemistry of Melanin-Mimetic Polydopamine Nanoparticles Drastically Enhances Their Accumulation into Excised Human Skin.

Melanin-mimetic polydopamine nanoparticles (PDA NPs) are emerging as promising candidates for topical and transdermal drug delivery because they mimic melanin, a naturally occurring skin pigment. However, our knowledge of their interactions with human skin remains limited. Hence, we set out to investigate the role of PDA NP surface chemistry in modulating their skin deposition. PDA NPs were synthesized by base-catalyzed oxidative self-polymerization of dopamine and functionalized with poly(ethylene glycol) (PEG) bearing different termini to obtain neutral, anionic, cationic, and hydrophobic PEGylated NPs. NPs were characterized by dynamic light scattering, transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray photoelectron spectroscopy. The NPs were then labeled with rhodamine B, and their skin interactions were investigated both in vitro, using a Strat-M membrane, and ex vivo, using excised whole thickness human skin. In vitro diffusion studies revealed that the NPs did not permeate transdermally, rather the NPs accumulated in the Strat-M membrane after 24 h of incubation. Membrane deposition of the NPs showed a strong dependence on surface chemistry, with anionic (unmodified and carboxyl-terminated PEGylated) NPs achieving the highest accumulation, followed by neutral and cationic NPs, whereas hydrophobic NPs achieved the lowest degree of accumulation. In ex vivo permeation studies, we observed that surface modification of PDA NPs with PEG serving as an antifouling coating is essential to maintaining colloidal stability upon skin contact. Moreover, anionic PEGylated NPs were able to achieve 78% skin accumulation, which was significantly higher than neutral and cationic NPs (51 and 34% accumulation, respectively). Our findings provide important insights into the role of surface chemistry in enhancing the skin accumulation of melanin-mimetic PDA NPs as potential sunscreens and carriers for skin-targeted treatments.

Effects of surface modified nanosilica on drilling fluid and formation damage

Despite the fact that hydrophobic nanosilica can improve the stability of water/oil emulsion, there exist controversies pertaining to its influence on oil-based drilling fluid rheological behavior and the subsequent formation damage. The present study addresses the above using a surface modified nanosilica, where the particles were functionalized with different silane-based groups to alter their hydrophilicity: 3-glycidoxypropyl-triethoxy silane (GPTS) and combined GPTS and propyl silane (PGPTS). The NPs were characterized through FTIR analysis, particle size, and zeta-potential measurements followed by flow behavior experiments, core-scale mud flow tests, Computed Tomography (CT) scanning and SEM imaging techniques to determine the mud penetration depth.We found that, depending on the type of functionalized group and the size of NPs, the surface modification of NPs can enhance the rheological properties and mitigate formation-damage. The most desirable behavior, both in terms of the plastic viscosity and yield stress, was achieved with 15 nm size NPs. The functionalized NP with the 3-glycidoxypropyl-triethoxy silane (GPTS@SiO2), which is less hydrophilic compared with bare NP, improved plastic viscosity of the drilling fluid, however slightly deteriorated the yield stress. This was compensated for by adding a double amount of GPTS on the surface of NP (DGPTS@SiO2), which was shown to be more effective than merely increasing the GPTS content in the drilling fluid. Further improvement of rheological properties was made by combining GPTS and propyl silane (PGPTS@SiO2); implying the positive effect of reducing hydrophilicity on both the plastic viscosity and yield stress. It is noteworthy that surface modifications were identified to be efficient below an optimal concentration of 1 wt% of NPs due to the lack of particle agglomeration. Moreover, a decreasing trend in plastic viscosity was observed against increasing temperature as a result of lowering viscosity of the continuous phase. Meanwhile, the yield stress experienced greater changes versus temperature due to the larger dependency of the interactions between drilling fluids components on temperature.In addition, the results were further validated through a series of core-flow tests which showed that with the aid of the nano-based drilling fluids (NDFs) containing DGPTS@SiO2 and GPTS@SiO2 the penetration depth of mud, thus the degree of internal formation damage can be significantly reduced.

Chitosan/TiO2 nanocomposites: Effect of microwave heating and solution mixing techniques on physical properties

Chitosan/titanium oxide nanocomposite (CS/TiO2 nanocomposite) could be prepared by different physical and chemical methods for various applications. CS/TiO2 nanocomposite has been chemically prepared via microwave heating technique and physically prepared through solution mixing method. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used as spectral tools to characterize the functionality, phase, morphology and particles size of the prepared nanocomposites, respectively. The thermal stability was investigated by the thermogravimetric analysis (TGA), while optical properties were studied using ultraviolet-visible spectroscopy (UV-vis).The results have confirmed that CS/TiO2 nanocomposite was chemically and physically prepared via the outer sphere complexation and the electrostatic repulsion between chitosan and titanium oxide nanoparticles surface (TiO2 NPs), respectively. The thermal stability was enhanced with nanocomposite prepared by chemical method when compared to that prepared by the physical method. In addition, a significant shift in the peak of the chemically prepared nanocomposite from the UV region to visible region was observed. This shift could be attributed to the surface modification of TiO2 NPs by the chemical reaction.

Doxorubicin-loaded PVP coated Gd2O3 NPs for effective chemoradiotherapy in melanoma

Combination of chemotherapy and radiotherapy (chemoradiotherapy) can synergistically improve the cytotoxic action of chemotherapeutic agents while reducing their side effects. Gadolinium oxide nanoparticles (Gd2O3 NPs) have significant potential as radiosensitizer agents because of their distinctive properties. The surface modification of Gd2O3 NPs with PVP can increase their biocompatibility. The aim of this study was to evaluate the combination of Gd2O3 NPs as radiosensitizer and doxorubicin (DOX) as chemotherapeutic agent to improve cancer chemoradiotherapy. Doxorubicin loaded PVP-coated Gd2O3 NPs (Gd2O3@PVP-DOX NPs) were developed. MTT, and clonogenic assays showed that the viability and surviving fraction of B16F10 melanoma cells were significantly inhibited by treating with Gd2O3@PVP-DOX NPs under radiation compared with treating with the free DOX or PVP-Gd2O3 NPs alone under radiation. Furthermore, significant sensitization occurred with a maximum dose enhancement factor of 2.51 for Gd2O3@PVP-DOX NPs after irradiation. The radiosensitization activity of Gd2O3 NPs and more entrance and retention of DOX in the tumor cells after loading in Gd2O3@PVP-DOX NPs could cause effective inhibition of melanoma tumor cells growth and proliferation. In conclusion, the Gd2O3@PVP-DOX NPs developed in this study could represent a promising strategy for improved cancer chemoradiotherapy in melanoma.

Tragacanth gum based hydrogel nanocomposites for the adsorption of methylene blue: Comparison of linear and non-linear forms of different adsorption isotherm and kinetics models

In the current work, novel eco-friendly hydrogel nanocomposite biosorbents (ef-HNCs) made up from tragacanth gum and modified CaCO3 nanoparticles (CC NPs) were applied for the adsorption of methylene blue dye (MBD). A simple, fast, and safe method regarding green chemistry was used to prepare the ef-HNC, with the aid of ultrasound waves. The ef-HNCs were successfully characterized using several spectroscopic, microscopic, and analytical methods. The results of the adsorption showed that the surface modification of CC NPs has a great impact on the adsorption and increased it and showed this process is more compatible with linear pseudo-first-order kinetic and linear Langmuir isotherm models. Also, thermodynamic parameters showed that the adsorption is spontaneous, although with an increase in temperature the adsorption decreased. Also, the value of the enthalpy and Gibb's free energy showed physiochemical adsorption. The maximum adsorption capacity calculated from linear Langmuir models as 468.62 mg/g, which is an appropriate value for the natural polymer. Furthermore, phenomenological methods displayed that the film diffusion is the predominant mechanism of this adsorption process.

Ultra-high FRET efficiency NaGdF4: Tb3+-Rose Bengal biocompatible nanocomposite for X-ray excited photodynamic therapy application

The limitation of light penetration depth invalidates the application of photodynamic therapy in deep-seated tumors. X-ray excited photodynamic therapy (X-PDT), which is based on X-rays excited luminescent nanoparticles (XLNP), provides a new strategy for PDT in deep tissues. However, the high X-ray dosage used and non-specific cytotoxicity of the nanoparticle-photosensitizer nanocomposite (NPs-PS) hamper in-vivo X-PDT applications. To address these problems, a simple and efficient NPs-PS nanocomposite using β-NaGdF4: Tb3+ nanoparticles and widely used PS called Rose Bengal (RB) was designed. With perfectly matched spectrum of NPs emission and RB absorption upon X-ray excitation and covalent conjugation of a large amount of RB on NP surfaces to minimize the energy transfer distance, the system demonstrated ultra-high FRET efficiency up to 99.739%, which leads to maximum production of singlet oxygen for PDT with significantly increased anti-tumor efficacy. By 2-aminoethylphosphonic acid surface modification of NPs, excellent biocompatibility was achieved even at a high concentration of 1 mg/mL. The in-vivo X-PDT efficacy was found around 90% of HepG2 tumor growth inhibition with X-ray dose of only 1.5 Gy, which shows the best anti-tumor efficacy at same X-ray dose level reported so far. The present work provides a promising platform for in-vivo X-PDT in deep tumors.

A Rapid and Sensitive Colorimetric Sensor for Detection of Silver Ions Based on the Non-aggregation of Gold Nanoparticles in the Presence of Ascorbic Acid

In the present work, we have developed a label free, colorimetric and non aggregation based gold nanoparticle (Au NPs)/Ascorbic acid (AA) probe without employing any aggregation agents for detection of trace amounts of silver ions (Ag+ ions) in aqueous solution and water samples. This detection probe can be prepared by simply mixing Au NPs with AA. The sensing mechanism is based on the reduction of Ag+ to Ag0 on the surface of Au NPs by AA. The addition of Ag+ ions to Au NPs/AA probe resulted in the enhancement and simultaneous blue shift of surface plasmon resonance band of Au NPs at 512 nm and it is accompanied by the appearance of a new peak around 385 nm. These observations are attributed to the deposition of Ag0 on the surface of Au NPs. This method could selectively detect Ag+ ions and showed a good linearity over the range of 2–28 μM (LOD = 0.85 μM). This sensing strategy avoids complex surface modification of Au NPs and it is cost effective.

Surface Chemical Modification of Si Nanoparticles for Application in Si-Based Anode

Silicon (Si), with its extremely high theoretical specific capacity (up to 4200 mAhg−1), natural abundance and low toxicity, is considered as one of the most promising anode material candidates for next generation high energy density lithium-ion batteries. However, large volume expansion (~300 %) upon lithiation/delithiation makes it difficult for Si-based anode to maintain its capacity over extended cycles. Several possible mechanisms have been proposed to explain the rapid capacity fade in Si-based anode such as pulverization of the active materials, loss of electrical pathways caused by rearrangement of electrode structure, instability of the electrode/electrolyte interface or some combinations of these. While application of nano-structured Si (nanoparticles, nanowires) as anode largely resolved the pulverization issue, the use of nano-silicon inevitably increases the reactive surface between active materials and the electrolyte. Additionally, the continuous growth of solid-electrolyte-interphase (SEI) on the particle surface remains a significant cause for performance deterioration. Therefore, an increasing number of research has focused on the correlation between surface functionality of Si NPs and their electrochemical performance. Previous studies in this area mainly focused on the study of the inherent SiOx layers on Si NPs or the effect of electrolyte additives on the surface properties of Si NPs. We take a different strategy to address the Si anode issue. We propose to chemically modify the surface of Si NPs and study how the chemical modification would affect the electrochemical performance of the Si-based anode. Commercially available Si NPs usually bear a native layer of silicon oxide on the surface of the particle. The first step in the surface modification of Si NPs is to enrich the surface silanol (Si-OH) groups as the new working platform. The silanol enriched surfaces will be converted to a variety of functional groups on the Si NPs. (Scheme 1). In this paper, we will present some preliminary results on the surface-modified Si NPs with methacrylate group and amine group and discuss the effects of the functional groups on the electrochemical performance of the Si anode. Scheme 1. Chemical surface modification of Si NPs via silane chemistry. Figure 1