Role Of Surface Functionalization Research Articles

Role of surface functionality in the electrochemical performance of silicon nanowire anodes for rechargeable lithium batteries.

We report the synthesis of silicon nanowires using the supercritical-fluid-liquid-solid growth method from two silicon precursors, monophenylsilane and trisilane. The nanowires were synthesized at least on a gram scale at a pilot scale facility, and various surface modification methods were developed to optimize the electrochemical performance. The observed electrochemical performance of the silicon nanowires was clearly dependent on the origination of the surface functional group, either from the residual precursor or from surface modifications. On the basis of detailed electron microscopy, X-ray photoelectron spectroscopy, and confocal Raman spectroscopy studies, we analyzed the surface chemical reactivity of the silicon nanowires with respect to their electrochemical performance in terms of their capacity retention over continuous charge-discharge cycles.

The Role of Surface Functionality in Nanoparticle Exocytosis

Getting out is just as important for nano-therapeutics as getting in. Exocytosis rates determine residency time in the cell, an important determinant for therapeutic efficacy and also for eventual clearance from the cell. In this study, it is shown that exocytosis efficiency is determined by surface functionality, providing a strategy for optimizing nanocarriers.

Role of surface functionalization in ZnO:Fe nanostructures

Abstract In this work, we have explored the effect of surface functionalization in ZnO:Fe nanostructures. The ZnO:Fe nanostructures (NS), synthesized through hydrothermal route, have been surface functionalized (capped) by Tri-n-butylamine (amine). These samples have been characterized by X-ray diffraction (XRD), photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR). Field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM) illustrate that obtained nanostructures are high aspect ratio nanorods. Room temperature Mossbauer spectra (MS) of the samples indicate the presence of paramagnetic iron state i.e. Fe3+ in ZnO host. The ferromagnetic (FM) behavior of the samples was investigated by vibrating sample magnetometer (VSM) which shows that the significant enhancement of saturation magnetization in amine capped ZnO:Fe samples. This observed/enhanced ferromagnetism has been explained in terms of modification in the ZnO conduction band. The enhanced ferromagnetism due to surface functionalization has been justified by XRD, PL, FTIR and MS.

The Role of Surface Functionality in Determining Nanoparticle Cytotoxicity

Surface properties dictate the behavior of nanomaterials in vitro, in vivo, and in the environment. Such properties include surface charge and hydrophobicity. Also key are more complex supramolecular interactions such as aromatic stacking and hydrogen bonding, and even surface topology from the structural to the atomic level. Surface functionalization of nanoparticles (NPs) provides an effective way to control the interface between nanomaterials and the biological systems they are designed to interact with. In medicine, for instance, proper control of surface properties can maximize therapeutic or imaging efficacy while minimizing unfavorable side effects. Meanwhile, in environmental science, thoughtful choice of particle coating can minimize the impact of manufactured nanomaterials on the environment. A thorough knowledge of how NP surfaces with various properties affect biological systems is essential for creating NPs with such useful therapeutic and imaging properties as low toxicity, stability, biocompatibility, favorable distribution throughout cells or tissues, and favorable pharmacokinetic profiles--and for reducing the potential environmental impact of manufactured nanomaterials, which are becoming increasingly prominent in the marketplace. In this Account, we discuss our research and that of others into how NP surface properties control interactions with biomolecules and cells at many scales, including the role the particle surface plays in determining in vivo behavior of nanomaterials. These interactions can be benign, beneficial, or lead to dysfunction in proteins, genes and cells, resulting in cytotoxic and genotoxic responses. Understanding these interactions and their consequences helps us to design minimally invasive imaging and delivery agents. We also highlight in this Account how we have fabricated nanoparticles to act as therapeutic agents via tailored interactions with biomacromolecules. These particles offer new therapeutic directions from traditional small molecule therapies, and with potentially greater versatility than is possible with proteins and nucleic acids.

Synthesis of highly loaded and well-controlled magnetic beads via emulsion polymerization

Superparamagnetic iron oxide (SPIO) incorporated polystyrene beads of uniform size distribution (∼170 nm) and high magnetic content (∼40%) are synthesized by emulsion styrene polymerization in the presence of functionalized SPIO. The role of surface functionality on the polymerization process and SPIO incorporation is investigated by carrying out styrene emulsion polymerizations with different functionalities on SPIO. A unique combination of oleic acid and (2-acetoacetoxy) ethyl methacrylate as surface ligands for SPIO is used to attain the best magnetic beads. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Cadmium(II) adsorption using functional mesoporous silica and activated carbon

The role of surface functionality on silica and carbonaceous materials for adsorption of cadmium(II) was examined using various mesoporous silica and activated carbon. Silica surfaces were principally functionalized by mono-amino- and mercapto-groups, while carboxylic group was introduced to the activated carbons by oxidation. Functional groups on silica surface were formed using grafting and co-condensation techniques in their preparation. Mono-amino group was found more effective than di- and tri-amino groups for cadmium(II) adsorption on the grafted silica. Mono-amino groups prepared by co-condensation adsorbed cadmium(II) as much as 0.25mmol/g compared to mercapto- and carboxyl-groups which adsorbed around 0.12mmol/g, whereas Langmuir adsorption affinities were as strong as 50–60L/mmol for all of the three functions. The working pH range was wider for mercapto- and carboxyl-functions than for amino-group. Basic site could be an adsorption center for amino-functional groups while ion exchange sites were found to work for the mercapto- and carboxyl-functions to adsorb cadmium(II) from aqueous phase. Based on the experimental results, surface functional groups rather than structure of silica and carbon seemed to play a decisive role for cadmium(II) adsorption.

The role of surface functionalization in the solar light-induced production of reactive oxygen species by single-walled carbon nanotubes in water

Risk assessment of engineered nanomaterials necessitates the need for information on reactivity and persistence of these materials in the environment. To this end, we report on reactivity of single-walled carbon nanotubes (SWCNTs) that: (i) have been functionalized by acid oxidation to contain carboxylic acid groups, (ii) have been further functionalized by esterification with polyethylene oxide groups, or (iii) were unmodified (i.e., unfunctionalized), with all materials used as received from the manufacturer. Aqueous colloidal dispersions of both types of functionalized SWCNTs generated reactive oxygen species (ROS) including singlet oxygen ( 1O 2), superoxide anion ( O 2 - ) , and hydroxyl radicals ( OH) in light within the solar spectrum ( λ = 300–410 nm) under oxic conditions. Under similar experimental conditions (i.e., several days under light near solar intensity) but with a surfactant added as a dispersing agent, aqueous dispersions of unfunctionalized SWCNTs exhibited no measurable ROS production. Defects in the surface caused by functionalization, as well as differences in amorphous carbon and metal impurity content within different SWCNT preparations, may facilitate some ROS production. Adding β-nicotinamide adenine dinucleotide to dispersions of carboxylated SWCNTs resulted in O 2 - generation in the absence of light, suggesting dark reaction electron transfer as a potential mechanism of toxicity.

The Role of Surface Functionality on Acute Cytotoxicity, ROS Generation and DNA Damage by Cationic Gold Nanoparticles

A poisoned chalice? Surface functionalization of 2 nm gold nanoparticles is an important determinant of their acute toxicity and genotoxicity. These attributes need to be considered for their use as carriers, and provide new direction for the design of therapeutics.

Just scratching the surface? New techniques show how surface functionality of nanoparticles influences their environmental fate

This Opinion Article highlights how new applications of techniques such as neutron scattering are offering greater insights into the processes, mechanisms and rates controlling the behaviour and fate of nanoparticles in different environmental compartments. Such information is vital for successful predictive modelling of the environmental fate of engineered nanoparticles in the post-production stages of their lifecycles. The role of surface functionality (surface coatings) in influencing environmental pathways of nanoparticles is specifically discussed.

The Role of Surface Functionalization in the Design of PLGA Micro- and Nanoparticles

Nano- and microcarriers prepared from the biocompatible and biodegradable polymer poly(D,L-lactide-co-glycolide) (PLGA) are being extensively studied for drug-delivery purposes. Apart from size, their fate in the body is mainly determined by surface characteristics that govern the interaction of the particles with their environment. The present review provides an overview of the currently established concepts for the surface functionalization of particles made from PLGA. In the first part, a concise description of the material-borne surface features and the related functionalization strategies are given, followed by current methods for the physical and chemical characterization of the particle surface. The second part highlights the aims of functionalization, which include improved drug delivery, vaccination, and imaging. Targeting approaches for site-specific delivery of drug-loaded particles to certain tissues or even to intracellular targets are presented, as well as stealth coatings for a prolonged blood circulation, labeling methods for imaging purposes, and strategies for the immobilization of macromolecular drugs on the particle surface. Finally, present limitations and future challenges will be discussed, with a focus on the surface-modification procedure and essential demands on functional particulate systems posed by the dynamic and complex in vivo environment.

Polymer/Carbon Nanotube Composites

The unique geometry and extraordinary mechanical, electrical, and thermal conductivity properties of carbon nanotubes (CNTs) make them ideal candidates as functional fillers for polymeric materials. In this paper we review the advances in both thermoset and thermoplastic CNT composites. The various processing methods used in polymer/CNT composite preparation; solution mixing, in-situ polymerization, electrospinning, and melt blending, are discussed. The role of surface functionalization, including ‘grafting to’ and ‘grafting from’ using atom transfer radical polymerization (ATRP), radical addition–fragmentation chain transfer polymerization (RAFT), and ring-opening metathesis polymerization (ROMP) in aiding dispersion of CNTs in polymers and interfacial stress transfer is highlighted. In addition the effect of CNT type, loading, functionality and alignment on electrical and rheological percolation is summarized. We also demonstrate the effectiveness of both Raman spectroscopy and oscillatory plate rheology as tools to characterize the extent of dispersion of CNTs in polymer matrices. We conclude by briefly discussing the potential applications of polymer/CNT composites and highlight the challenges that remain so that the unique properties of CNTs can be optimally translated to polymer matrices.

Nanodiamond Particles in Electronic and Optical Applications

AbstractCurrent use of nanodiamond (ND) particles in electronic-related applications is mostly restricted to their role in seeding of substrates for growth of diamond films by chemical vapor deposition (CVD). While it is a niche application, nanometer-sized diamond particles are indispensable in this role. Seeding of substrates using a novel slurry of detonation nanodiamond particles in dimethylsulfoxide (DMSO) and methanol is one of the topics of this article. At the same time, optical applications of NDs, particularly development of photoluminescent NDs for biomedical applications is one of the most popular current research topics. In this paper perspectives for the use of detonation NDs and specifically the role of surface functionalization in imparting photoluminescent properties to detonation NDs as well as enhanced photoluminescence of proton irradiated ND-polydimethylsiloxane composites are discussed.

Selective Nucleation of Calcium Carbonate Polymorphs: Role of Surface Functionalization and Poly(Vinyl Alcohol) Additive

A model system involving a synthetic polyamide fiber and a water-soluble polymer for the selective nucleation of polymorphs of calcium carbonate crystals under specific experimental conditions is described. The functional groups at the surface of both commercially available and chemically modified polyamide fibers induced calcite nucleation. A water-soluble additive, poly(vinyl alcohol) (PVA), enhanced the selectivity of the polymorph nucleation. The unmodified fiber preadsorbed with PVA molecules induced vaterite nucleation, whereas the chemically modified fiber surface in the presence of PVA nucleated aragonite crystals. Morphological characterization of the polymorphs was done using scanning electron microscope (SEM), and the nature of the crystal lattice was identified using X-ray diffraction studies. Elemental analyses of the crystals indicated the absence of a soluble macromolecular additive inside the crystal lattice. On the basis of these results, a possible mechanism for the nucleation of CaCO3 polymorphs is proposed.