Chemical Properties Of Nanoparticles Research Articles

Protein-Mimicking Nanoparticles for a Cellular Regulation of Homeostasis

The distinct physical and chemical properties of nanoparticles (NPs) offer great opportunities to develop new strategies for diagnostic and therapeutic purposes. Whereas NPs often serve as inert nanocarriers, their inherent "biological" activities have recently been extensively unveiled and explored. These protein-mimicking NPs (dubbed protmins) have been reported to modulate a cellular homeostasis without displaying a general toxicity, which may act as potential nanomedicines to provide a monotherapy or combination therapy in a disease treatment. In the meanwhile, the unexpected behaviors of protmins in complex biological systems also raise new concerns on the biosafety issue. Herein, we summarize several categories of the protmin-based regulation of cellular homeostasis and discuss their broad effects on cell functions and behaviors.

Mechanisms underlying the strength enhancement of UHPC modified with nano-SiO2 and nano-CaCO3

The unique physical and chemical properties of nano-particles can enhance the nature of cement-based materials at the micro-scale and nano-scale levels, leading to improved properties. To uncover the strengthening mechanism associated with various types of nano-particles, a laboratory investigation was undertaken to evaluate and compare the influence of nano-SiO2 and nano-CaCO3 on mechanical properties of ultra-high performance concrete (UHPC) made with 2% steel fibers. Each type of nano-particle was incorporated at four contents, and the mini-slump flow of the UHPC was maintained at 240–260 mm. The microstructure of the matrix and the fiber-matrix interface of UHPC, as well as the features of hydration products were characterized using advanced techniques, such as electron microscopy (SEM), X-ray diffraction (XRD), differential thermal gravimetric (DTG) analyses, 3D micro-tomography, and mercury intrusion porosimetry (MIP). Test results indicate that both the fiber-matrix strength and mechanical strength of UHPC increased with the increase of nano-SiO2 and nano-CaCO3 until threshold limits of 1% and 3.2%, respectively. The 28-d fiber-matrix bond, compressive, and flexural strengths of the optimal UHPC mixtures made with 3.2% nano-CaCO3 were approximately 40%, 10%, and 20%, respectively, greater than those of the reference mixture. These strength values were higher than those of UHPC made with 1% nano-SiO2. When used below these optimal nano-material contents, the filler and nucleation effects related of the nano-SiO2 and nano-CaCO3 promoted the strength development through improved density and homogeneity with optimized structure of hydration products, as indicated by SEM observation and DTG analysis. Beyond these limits, additional use of nano-materials resulted in increased volume of air voids and capillary pores and weak interfacial zones due to the agglomeration of nano-particles, which hindered strength development.

Green Synthesis of Metallic Nanoparticles and Their Prospective Biotechnological Applications: an Overview.

The green synthesis of nanoparticles (NPs) using living cells is a promising and novelty tool in bionanotechnology. Chemical and physical methods are used to synthesize NPs; however, biological methods are preferred due to its eco-friendly, clean, safe, cost-effective, easy, and effective sources for high productivity and purity. High pressure or temperature is not required for the green synthesis of NPs, and the use of toxic and hazardous substances and the addition of external reducing, stabilizing, or capping agents are avoided. Intra- or extracellular biosynthesis of NPs can be achieved by numerous biological entities including bacteria, fungi, yeast, algae, actinomycetes, and plant extracts. Recently, numerous methods are used to increase the productivity of nanoparticles with variable size, shape, and stability. The different mechanical, optical, magnetic, and chemical properties of NPs have been related to their shape, size, surface charge, and surface area. Detection and characterization of biosynthesized NPs are conducted using different techniques such as UV-vis spectroscopy, FT-IR, TEM, SEM, AFM, DLS, XRD, zeta potential analyses, etc. NPs synthesized by the green approach can be incorporated into different biotechnological fields as antimicrobial, antitumor, and antioxidant agents; as a control for phytopathogens; and as bioremediative factors, and they are also used in the food and textile industries, in smart agriculture, and in wastewater treatment. This review will address biological entities that can be used for the green synthesis of NPs and their prospects for biotechnological applications.

Highly Efficient AuPd Catalyst for Synthesizing Polybenzoxazole with Controlled Polymerization

Summary Using nanoparticles (NPs) to catalyze chemical reactions for the formation of functional polymers with controlled polymerization is an important field of chemical research. In this article, we report an AuPd NP system as an active and stable catalyst to catalyze one-pot reaction of formic acid, 1,5-diisopropoxy-2,4-dinitrobenzene, and terephthaldehyde, leading to the controlled polymerization and the formation of polybenzoxazole (PBO) (Mw = 3.6 kDa). The one-pot reaction is AuPd NP size and composition dependent, and 8-nm Au39Pd61 NPs are the best catalyst for the polymerization. The highly pure PBO shows excellent thermal stability up to 600°C and improved chemical and mechanical stability under challenging environmental conditions compared with commercial PBO (Zylon, Mw = 40 kDa). The reported NP-catalyzed one-pot reaction to polymerization is not limited to the formation of PBO but can be extended as a general approach to rigid polymers that are important for ballistic fiber, anti-flame, and smart-textile applications.

Durability of concrete with nano-particles under combined action of carbonation and alkali silica reaction

ABSTRACTSubway concrete is easy to be attacked by carbonation in the relatively closed space, and alkali silica reaction (ASR) is a serious durability problem of concrete, which is difficult to find and repair. The damage caused by carbonation and ASR seriously affects the durability of subway concrete. Two kinds of nano-particles (nano-SiO2 and nano-Fe2O3) are mixed into plain subway concrete in this paper, and their effects on the durability of concrete under the combined action of carbonation and ASR are studied experimentally. The test results show that, after mixing with nano-particles, the carbonation depth and expansion of subway concrete are decreased, as well as the sonic velocity of subway concrete is increased obviously, which demonstrate the durability of subway concrete with nano-particles is better than plain subway concrete. The enhancement of durability is due to the special physical and chemical properties of nanoparticles, which can improve the microstructure of concrete and the chemical composition of pore solution in concrete.

Comparison of a theoretical and experimental thermal conductivity model on the heat transfer performance of Al2O3-SiO2/water hybrid-nanofluid

The use of hybrid nanofluids has been drawing attention of researchers in order to overcome the drawbacks of mono nanofluid and combine the physical and chemical properties of nanoparticles in a useful way. In the literature, a growing number of researches have been devoted to investigate the thermal performance of hybrid nanofluids. A significant amount of these researches are built on the theoretical correlations for the estimation of thermophysical properties of nanofluids. In the present study, a comparative study is conducted to reveal the influence of theoretical and experimental correlations on the heat transfer performance of hybrid nanofluids. Within this aim, theoretical and experimental based models for predicting thermal conductivity of hybrid nanofluid are evaluated by considering natural convection in a square cavity, which has been studied extensively in the literature. In the study, the natural convection of Al2O3/water, SiO2/water nanofluids and their hybrid combinations are investigated numerically for two different Rayleigh numbers (Ra = 104 and 105) and three different particle volume fractions (ϕ = 1, 2 and 3%). The comparative analysis considering the studied parameters was performed in terms of local and mean Nusselt numbers. The results showed that employing theoretical models for thermal conductivity underestimates the heat transfer performance of both mono and hybrid nanofluids. Furthermore, it is surprising that the theoretically calculated SiO2/water nanofluid deteriorated the heat transfer performance. It was also observed that hybridizing the nanoparticles could perform the same heat transfer enhancement at a lower particle volume fraction compared to mono nanofluid (Al2O3).

The role of apolipoprotein- and vitronectin-enriched protein corona on lipid nanoparticles for in vivo targeted delivery and transfection of oligonucleotides in murine tumor models.

The application of lipid-based nanoparticle (LNP) delivery systems remains a popular strategy for the systemic delivery of gene therapies to specific disease targets, including solid tumors. It is now well acknowledged that upon systemic administration, biomolecules from blood will adsorb onto nanoparticles' surfaces, forming a "protein corona", affording nanoparticles a "biological identity" on top of their "synthetic identity". Detailed analysis of nanoparticle protein corona is gradually revealing the "missing link" between nanoparticle chemical properties and the biological identity. Nevertheless, the discovery of nanoparticle protein corona's impact on tumor delivery is limited. In this study, we demonstrate that protein corona can be manipulated by formulation composition and particle surface charge changes, and a single lipid switch could switch the nanoparticle protein corona profile. The protein corona composition differences had a profound impact on cell transfection, in vivo biodistribution as well as tumor-specific delivery efficiency. Nanoparticles with apolipoprotein-rich corona showed better delivery to hepatocellular carcinoma (HepG2) as compared to those with vitronectin-rich corona. In addition, we found that, the PEG conjugated lipid chain length and PEG amount in LNPs were key factors to consider in successful RNA interference therapy for solid tumors.

Nanoparticles having amphiphilic silane containing Chlorin e6 with strong anti-biofilm activity against periodontitis-related pathogens

ObjectivesThe objectives of this study were to: (1) develop the multifunctional nanoparticles containing Chlorin e6 (Ce6), Coumarin 6 (C6) and Fe3O4 nanoparticles (NPs); and (2) investigate the inhibitory effects of the nanoparticles via antibacterial photodynamic therapy (aPDT) against three species of periodontitis-related pathogens for the first time. Materials and methodsCe6 and C6 were co-loaded into the Fe3O4-silane core-shell structure to form multifunctional nanoparticles (denoted “Fe3O4-silane@Ce6/C6 MNPs”). The physical and chemical properties of nanoparticles were characterized. Biofilm properties of Streptococcus sanguinis, Porphyromonas gingivalis and Fusobacterium nucleatum were tested. Colony-forming units (CFU), live/dead assay, and metabolic activity of biofilms were determined to evaluate the aPDT function mediated by the Fe3O4-silane@Ce6/C6 MNPs. Fluorescence imaging and the targeted antibacterial effects were also investigated. ResultsFe3O4-silane@Ce6/C6 MNPs showed superparamagnetic properties, chemical stability and water-solubility, with no cytotoxicity. Fe3O4 NPs did not compromise the emission peaks of C6 and Ce6. The Fe3O4-silane@Ce6/C6-mediated aPDT had much greater reduction in biofilms than the control groups (p < 0.05). Biofilm CFU was reduced by about 4–5 orders of magnitude via Fe3O4-silane@Ce6/C6-mediated aPDT. The co-loading of Ce6 and C6 enabled the real-time aPDT monitoring by ratio emissions with the same wavelength. Fe3O4 with magnetic field enabled the targeting of infection sites by killing bacteria via magnetic field. ConclusionThe multifunctional nanoparticles exerted strong anti-biofilm activity against periodontitis-related pathogens, with excellent biocompatibility, real-time monitoring, and magnetically-targeting capacities. The multifunctional nanoparticles have great potential in antibacterial applications to inhibit the occurrence and progression of periodontitis.

Inhibition of growth and biofilm formation of clinical bacterial isolates by NiO nanoparticles synthesized from Eucalyptus globulus plants

Nanotechnology based therapeutics has emerged as a promising approach for augmenting the activity of existing antimicrobials due to the unique physical and chemical properties of nanoparticles (NPs). Nickel oxide nanoparticles (NiO-NPs) have been suggested as prospective antibacterial and antitumor agent. In this study, NiO-NPs have been synthesized by a green approach using Eucalyptus globulus leaf extract and assessed for their bactericidal activity. The morphology and purity of synthesized NiO-NPs determined through various spectroscopic techniques like UV-Visible, FT-IR, XRD, EDX and electron microscopy differed considerably. The synthesized NiO-NPs were pleomorphic varying in size between 10 and 20 nm. The XRD analysis revealed the average size of NiO-NPs as 19 nm. The UV-Vis spectroscopic data showed a strong SPR of NiO-NPs with a characteristic spectral peak at 396 nm. The FTIR data revealed various functional moieties like C=C, C–N, C–H and O–H which elucidate the role of leaf biomolecules in capping and dispersal of NiO-NPs. The bioactivity assay revealed the antibacterial and anti-biofilm activity of NiO-NPs against ESβL (+) E. coli, P. aeruginosa, methicillin sensitive and resistant S. aureus. Growth inhibition assay demonstrated time and NiO-NPs concentration dependent decrease in the viability of treated cells. NiO-NPs induced biofilm inhibition was revealed by a sharp increase in characteristic red fluorescence of PI, while SEM images of NiO-NPs treated cells were irregular shrink and distorted with obvious depressions/indentations. The results suggested significant antibacterial and antibiofilm activity of NiO-NPs which may play an important role in the management of infectious diseases affecting human health.

Protease-activated nanomaterials for targeted cancer theranostics.

Cancer metastasis accompanies irreversible proteolysis. Malignant cells that abnormally express extracellular proteases usually lead to a poor outcome during cancer progression. The development of protease-activated drugs is an important goal. Moreover, the specific proteolytic mechanism can be used as a diagnostic strategy. Currently, nanotechnology for use in medication has been extensively developed to exploit the physical and chemical properties of nanoparticles. For example, to improve the efficacy of cancer therapy drugs, targeted delivery has been attempted by combining a targeting ligand with a nanoparticle. Multifunctional nanoparticles have been prepared for cancer therapy and diagnosis because of their advantages such as stable physical properties, drug carrying ability and potential specific targeting ability. In this review, we present reports on protease-activated nanoparticle design for cancer theranostics. We further describe recent protease-activated metalloprotease-based and cathepsin-based nanomaterials used in cancer nanotheranostics. Innovative protease-activated nanomaterials have significant potential for designing personalized treatment.

Accelerated oral nanomedicine discovery from miniaturized screening to clinical production exemplified by paediatric HIV nanotherapies

Considerable scope exists to vary the physical and chemical properties of nanoparticles, with subsequent impact on biological interactions; however, no accelerated process to access large nanoparticle material space is currently available, hampering the development of new nanomedicines. In particular, no clinically available nanotherapies exist for HIV populations and conventional paediatric HIV medicines are poorly available; one current paediatric formulation utilizes high ethanol concentrations to solubilize lopinavir, a poorly soluble antiretroviral. Here we apply accelerated nanomedicine discovery to generate a potential aqueous paediatric HIV nanotherapy, with clinical translation and regulatory approval for human evaluation. Our rapid small-scale screening approach yields large libraries of solid drug nanoparticles (160 individual components) targeting oral dose. Screening uses 1 mg of drug compound per library member and iterative pharmacological and chemical evaluation establishes potential candidates for progression through to clinical manufacture. The wide applicability of our strategy has implications for multiple therapy development programmes.

Direct observation of interfacial Au atoms on TiO₂ in three dimensions.

Interfacial atoms, which result from interactions between the metal nanoparticles and support, have a large impact on the physical and chemical properties of nanoparticles. However, they are difficult to observe; the lack of knowledge has been a major obstacle toward unraveling their role in chemical transformations. Here we report conclusive evidence of interfacial Au atoms formed on the rutile (TiO2) (110) surfaces by activation using high-temperature (∼500 °C) annealing in air. Three-dimensional imaging was performed using depth-sectioning enabled by aberration-corrected scanning transmission electron microscopy. Results show that the interface between Au nanocrystals and TiO2 (110) surfaces consists of a single atomic layer with Au atoms embedded inside Ti-O. The number of interfacial Au atoms is estimated from ∼1-8 in an interfacial atomic column. Direct impact of interfacial Au atoms is observed on an enhanced Au-TiO2 interaction and the reduction of surface TiO2; both are critical to Au catalysis.

Structural optimization of Pt–Pd alloy nanoparticles using an improved discrete particle swarm optimization algorithm

Pt–Pd alloy nanoparticles, as potential catalyst candidates for new-energy resources such as fuel cells and lithium ion batteries owing to their excellent reactivity and selectivity, have aroused growing attention in the past years. Since structure determines physical and chemical properties of nanoparticles, the development of a reliable method for searching the stable structures of Pt–Pd alloy nanoparticles has become of increasing importance to exploring the origination of their properties. In this article, we have employed the particle swarm optimization algorithm to investigate the stable structures of alloy nanoparticles with fixed shape and atomic proportion. An improved discrete particle swarm optimization algorithm has been proposed and the corresponding scheme has been presented. Subsequently, the swap operator and swap sequence have been applied to reduce the probability of premature convergence to the local optima. Furthermore, the parameters of the exchange probability and the ‘particle’ size have also been considered in this article. Finally, tetrahexahedral Pt–Pd alloy nanoparticles has been used to test the effectiveness of the proposed method. The calculated results verify that the improved particle swarm optimization algorithm has superior convergence and stability compared with the traditional one.

Characteristic Taylor cone formation time optimisation of electrospray systems

Characteristic Taylor cone formation time optimisation of electrospray systems Electrospray atomisation is a process during which nanometre sized particles are simultaneously generated and charged by an electrostatic field. This paper optimises the Taylor cone formation time of electrospray systems. Using the obtained model, the limitations on the nanoparticle chemical properties can be determined semi-analytically for a given geometry.

Review on characterization of nano-particle emissions and PM morphology from internal combustion engines: Part 1

This paper is review of the characterization of exhaust particles from state-of-the-art internal combustion engines. We primarily focus on identifying the physical and chemical properties of nano-particles, i.e., the concentration, size distribution, and particulate matter (PM) morphology. Stringent emissions regulations of the Euro 6 and the LEV III require a substantial reduction in the PM emissions from vehicles, and improvements in human health effects. Advances in powertrains with sophisticated engine control strategies and engine after-treatment technologies have significantly improved PM emission levels, motivating the development of new particle measurement instruments and chemical analysis procedures. In this paper, recent research trends are reviewed for physical and chemical PM characterization methods for gasoline and diesel fueled engines under various vehicle certification cycles and real-world driving conditions. The effects of engine technologies, fuels, and engine lubricant oils on exhaust PM morphology and compositions are also discussed.

Physicochemical characterization of nanoparticles and their behavior in the biological environment.

Whilst the physical and chemical properties of nanoparticles in the gas or idealized solvent phase can nowadays be characterized with sufficient accuracy, this is no longer the case for particles in the presence of a complex biological environment. Interactions between nanoparticles and biomolecules are highly complex on a molecular scale. The detailed characterization of nanoparticles under these conditions and the mechanistic knowledge of their molecular interactions with the biological world is, however, needed for any solid conclusions with regards to the relationship between the biological behavior of such particles and their physicochemical properties. In the present article we discuss some of the challenges with characterization and behavior of nanoparticles that are associated with their presence in chemically complex biological environments. Our focus is on the stability of colloids as well as on the formation and characteristics of protein coronae that have recently been shown to significantly modify the properties of pristine particles. Finally, we discuss the perspectives that may be expected from an improved understanding of nanoparticles in biological media.

Applications of Nanoparticles for Treating Cutaneous Infection

Today, nanotechnology is finding applications in medicine. The unique physical and chemical properties of nanoparticles can overcome barriers and allow them to gain access to biological systems. Because of the increasing prevalence of microbial resistance to conventional therapies, the development of novel antimicrobials is imperative. Creating nanotechnology-based drug delivery systems with antibacterial and immunomodulatory activities may lead to novel treatments for cutaneous pathogens.

Sensing Uric Acid with Bimetallic Nano Ag-Pt Particles

The emergence of nanoparticles (NPs) has opened new opportunities in analytical chemistry [. These NPs exhibit different properties and functionalities when compared to monometallic particles. In particular, they show enhanced selectivity and reactivity when used as catalysts and sensors [2-. The NPs have large surface area, high surface free energy, good biocompatibility and suitability, and it has been used in constructing electrochemical biosensors [7, . The fascinating physical and chemical properties of NPs offer excellent prospects for a wide range of bio sensing applications [ . Uric acid (UA) is the principal final product of purine metabolism in the human body [1. It has been shown that extreme abnormalities of UA levels are symptoms of several diseases (e.g. gout, hyper uricaemia and LeschNyhan syndrome)[11,1.In general, electro active UA can be irreversibly oxidized in aqueous solution and the major product is allantoin [1. In continuation of our interest with the bimetal nanoparticle (BNP) sensing here in this study, we employed Ag/Pt BNPs for detecting of UA.

Emerging Scope of Hybrid Solar Cells in Organic Photovoltaic Applications by Incorporating Nanomaterials

In recent years, semiconductor nanomaterials have been extensively studied and reports are available for their preparation methods, physical and chemical properties of nanoparticles and their characterization techniques. Because of their potential applications, ZnS nanoparticles are recently major area of research. It is an important inorganic material for a variety of applications including photoconductors, solar cells, field effect transistors, sensors, transducers optical coatings and light-emitting materials. Inorganic nano-particles have found potential application in various electronic devices. Synthesis, shape and size control are important issues for nano-particles research. Various nano-structured materials have found potential applications in optical and electrical devices such as photoconductors, LEDs, solar cells, field effect transistors, optical coatings etc. ZnS has wide band gap ranging from 3.5 to 3.8 eV at room temperature and the band gap can be tuned in the UV region by controlling the size of the nano-particles. In the present work we have studied the synthesis of ZnS nano-particles, their characterization to investigate various properties such as size, structure, band gap and luminescence via different characterization tools. The particles were then used as acceptors for fabrication of organic hybrid solar cells.

Experimental Study on Permeability and Mechanical Properties of Nanomodified Porous Concrete

Porosity of porous concrete is an important parameter used for both mechanical properties of pavement and environmental design. Nano-particles have received increasing attention and have been used in various fields such as concrete to develop novel materials with interesting functions, all because of dedicated physical and chemical properties of nanoparticles. The authors describe new findings of an experimental work on mechanical properties and permeability of porous concrete containing nano-silicon dioxide. Plain porous concrete and porous concrete containing micro-silicon dioxide have been studied as control materials. Twenty-eight-day results showed higher compressive and flexural strengths for porous concrete containing nano-silicon dioxide compared with those of plain porous concrete with the same water–cement ratio. It was demonstrated that nano-silicon dioxide was more effective than micro-silicon dioxide in enhancing porous concrete flexural strength. Samples with 5% nano-silicon dioxide by weight of binder presented the highest mechanical properties, in which the flexural and compressive strength of porous concrete were enhanced by 56% and 48%, respectively. From experimental study of the permeability behavior of porous concrete containing nano- and micro-silicon dioxide, it appeared that nano-silicon dioxide and micro-silicon dioxide could both reduce water penetration through porous concrete; however, micro-silicon dioxide was found more effective for equal nanoparticles and material voids.