Biomaterials with nanoscale topography have been increasingly investigated for medical device applications to improve tissue-material interactions. This study assessed the impact of nanoengineered titanium surface domain sizes on early biological responses that can significantly affect tissue interactions. Nanostructured titanium coatings with distinct nanoscale surface roughness were deposited on quartz crystal microbalance with dissipation (QCM-D) sensors by physical vapor deposition. Physico-chemical characterization was conducted to assess nanoscale surface roughness, nano-topographical morphology, wettability, and atomic composition. The results demonstrated increased projected surface area and hydrophilicity with increasing nanoscale surface roughness. The adsorption properties of albumin and fibrinogen, two major plasma proteins that readily encounter implanted surfaces, on the nanostructured surfaces were measured using QCM-D. Significant differences in the amounts and viscoelastic properties of adsorbed proteins were observed, dependent on the surface roughness, protein type, protein concentration, and protein binding affinity. The impact of protein adsorption on subsequent biological responses was also examined using qualitative and quantitative in vitro evaluation of human platelet adhesion, aggregation, and activation. Qualitative platelet morphology assessment indicated increased platelet activation/aggregation on titanium surfaces with increased roughness. These data suggest that nanoscale differences in titanium surface roughness influence biological responses that may affect implant integration.

Understanding the interactions of biomacromolecules with nanoengineered surfaces is vital for assessing material biocompatibility.This study focuses on the dynamics of protein adsorption on nanopatterned block copolymers (BCPs).Poly(styrene)-block-poly(1,2-butadiene) BCPs functionalized with an acid, amine, amide, or captopril moieties were processed to produce nanopatterned films.These films were characterized using water contact angle measurements and atomic force microscopy in air and liquid to determine how the modification process affected wettability and swelling.Protein adsorption experiments were conducted under static and dynamic conditions via a quartz crystal microbalance with dissipation.Proteins of various size, charge, and stability were investigated to determine whether their physical characteristics affected adsorption.Signifi-cantly decreased contact angles were caused by selective swelling of modified BCP domains.The results indicate that nanopatterned chemistry and experimental conditions strongly impact adsorption dynamics.Depending on the structural stability of the protein, polyelectrolyte surfaces significantly increased adsorption over controls.Further analysis suggested that protein stability may correlate with dissipation versus frequency plots.

This study was performed to understand how the choice of cytotoxicity assay format affects the observed biocompatibility of nanosilver (nAg). nAg coatings are physical coatings containing silver (Ag) that have feature sizes of 100nm or less, often in the form of nanoparticles or grains. They are used on medical devices to prevent infection, but in spite of this intended benefit, observations of potential cytotoxicity from nAg have been reported in numerous published studies. For medical device regulation, cytotoxicity testing is part of a biocompatibility evaluation, in which specific test methods are chosen based on the technological characteristics and intended use of a device. For this study, nAg-coated tissue culture polystyrene surfaces were prepared using magnetron sputter coating, resulting in nAg films of 0.2 to 311 mu gcm(-2) Ag. These coatings exhibited nanometer-scale morphologies and demonstrated a>4log(10) reduction in Escherichia coli viability. It was observed that extracts of nAg caused no cytotoxicity to L929 mouse fibroblasts, but cells cultured directly on nAg coatings (direct-contact assay format) showed a dose-dependent reduction in viability by up to 100% (P<0.001). Results using inductively coupled plasma mass spectrometry to measure Ag release suggested that extracts of nAg are not toxic because the dissolved Ag in those samples becomes less cytotoxic over time, probably owing to the reaction with cell culture media and serum (six-fold cytotoxicity reductions observed over a 24-h period). These findings highlight the potential value of direct-contact cytotoxicity testing for nAg in predicting biological interactions with cells or tissue in vivo. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

The focus of this research was to develop a better understanding of the pertinent physico-chemical properties of silver nanoparticles (AgNPs) that affect genotoxicity, specifically how cellular uptake influences a genotoxic cell response. The genotoxicity of AgNPs was assessed for three potential mechanisms: mutagenicity, clastogenicity and DNA strand-break-based DNA damage. Mutagenicity (reverse mutation assay) was assessed in five bacterial strains of Salmonella typhimurium and Echerichia coli, including TA102 that is sensitive to oxidative DNA damage. AgNPs of all sizes tested (10, 20, 50 and 100nm), along with silver nitrate (AgNO3), were negative for mutagenicity in bacteria. No AgNPs could be identified within the bacteria cells using transmission electron microscopy (TEM), indicating these bacteria lack the ability to actively uptake AgNPs 10nm or larger. Clastogenicity (flow cytometry-based micronucleus assay) and intermediate DNA damage (DNA strand breaks as measured in the Comet assay) were assessed in two mammalian white blood cell lines: Jurkat Clone E6-1 and THP-1. It was observed that micronucleus and Comet assay end points were inversely correlated with AgNP size, with smaller NPs inducing a more genotoxic response. TEM results indicated that AgNPs were confined within intracellular vesicles of mammalian cells and did not penetrate the nucleus. The genotoxicity test results and the effect of AgNO3 controls suggest that silver ions may be the primary, and perhaps only, cause of genotoxicity. Furthermore, since AgNO3 was not mutagenic in the gram-negative bacterial Ames strains tested, the lack of bacterial uptake of the AgNPs may not be the major reason for the lack of genotoxicity observed.

There is concern over the release of silver nanoparticles (AgNPs) from medical devices due to their potential toxicological consequences inside the body. Towards developing the exposure component of a risk assessment model, the purpose of this study was to determine the amount and physical form of silver released from medical devices. Scanning electron microscopy was used to confirm that three of five marketed medical devices contained nanosilver coatings (mean feature sizes 115-341 nm). Aqueous device extracts (water, saline and human plasma) were analyzed with inductively coupled plasma mass spectrometry, ultraviolet-visible spectroscopy, dynamic light scattering, transmission electron microscopy, and nanoparticle tracking analysis. The amount of silver extracted from the devices ranged from 1 × 10(-1) to 1 × 10(6) ng/cm(2) (conditions ranged from 37 to 50 °C, over one hour to seven days). The results further indicated that one of the five devices (labeled MD1) released significantly more AgNPs than the other devices. This data suggests that some but not all devices that are formulated with nanosilver may release detectable levels of AgNPs upon extraction. Further work is underway to quantitate the proportion of silver released as AgNPs and to incorporate this data into a risk assessment for AgNP exposure from medical devices.

Due to their unique properties, the use of nanoparticles (NPs) is expanding; these same properties may affect their potential risk to humans. However, standard methods for genotoxicity assessment may not be adequate for NPs; altered tests reported here have been developed to address perceived inadequacies. The bacterial reverse mutation assay is an essential part of the battery of tests to determine genotoxicity. The utility of this test for assessing NPs is currently questioned, due to negative results seemingly caused by failure of particle uptake. To probe uptake issues, we examined the physical state in different media, dose and time dependent association, uptake and mutagenicity of titanium dioxide (TiO2) NPs in Salmonella typhimurium and Escherichia coli. The NPs suspended in water were characterized using dynamic light scattering, NP tracking analysis and transmission electron microscopy. NP association with bacteria was assessed by flow cytometry. Association was found to be time and dose dependent, with maximal association by 60 min. Therefore mutagenicity was assessed after a 60 min pre-incubation in a miniaturized assay demonstrating enhanced sensitivity. To assess potential indirect effects on bacterial mutagenicity, the effect of TiO2 NPs on the action of standard mutagens or on DNA repair capability was also investigated. TiO2 NPs did not affect mutant yields in standard strains of S. typhimurium or E. coli, including those detecting oxidative damage, using the modified methods. Nor did TiO2 NPs affect the action of standard mutagens or DNA excision repair capability. Despite particle association with the bacteria, subsequent analysis using electron microscopy and energy dispersive x-ray spectroscopy indicated that the NPs were not internalized. This work demonstrates that additional studies, including flow cytometry, are valuable tools for understanding the action of NPs in biological systems.

Two model nanoengineered surfaces, a nanopatterned block copoloymer (BCP) film and a polymer nanofiber surface, were utilized to investigate the affect that nanofeatures have on protein adsorption. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the topography of the surfaces. Protein adsorption was quantified using a bicinchoninic acid (BCA) based assay. Future work will focus on investigating the mechanisms and dynamics of adsorption on surfaces with nanoscale features. This data will provide a better understanding of how these surfaces will react in the body.

Diblock and triblock copolymers of poly(styrene)-block-poly(1,2-butadiene) (PS/PB) and PS/PB/PS were modified by photochemical thiol–ene chemistry to process selected functional nanopatterned polymers, with reaction completion in 1 h. PB molecular weight (MW) and thiol–ene ratios were systematically varied based on a model monomer, boc-cysteamine, to determine the efficiency of the reaction. The results demonstrate the polydispersity index (PDI) of modified block copolymers significantly increased when low thiol–ene ratios were employed and sometimes induced gelation of the reacted polymers. Using a 10-fold excess of thiol, functionalizations between 60% and 90% were obtained for amines, carboxylic acids, amides, and a pharmaceutical with a pendant thiol. Differential scanning calorimetry showed a 30–60 °C increase in the glass transition temperature of the daughter polymers. Subsequently, these polymers were spin-coated from solvents found suitable to form self-assembled block copolymer films. The micros...

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTAnalyzing Nanomaterial Bioconjugates: A Review of Current and Emerging Purification and Characterization TechniquesKim E. Sapsford*†, Katherine M. Tyner‡, Benita J. Dair§, Jeffrey R. Deschamps∥, and Igor L. Medintz*∥View Author Information§ †Division of Biology, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, ‡Division of Drug Safety Research, Office of Testing and Research, Office of Pharmaceutical Science Center for Drug Evaluation and Research, and §Division of Chemistry and Materials Science, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993, United States∥ Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, 4555 Overlook Avenue, S.W. Washington, DC 20375, United StatesE-mail: [email protected] (K.E.S.); [email protected] (I.L.M.).Cite this: Anal. Chem. 2011, 83, 12, 4453–4488Publication Date (Web):May 5, 2011Publication History Published online5 May 2011Published inissue 15 June 2011https://doi.org/10.1021/ac200853aCopyright © This article not subject to U.S. Copyright. Published 2011 by the American Chemical SocietyRIGHTS & PERMISSIONSArticle Views9915Altmetric-Citations381LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (13 MB) Get e-AlertsSUBJECTS:Fluorescence,Metal nanoparticles,Nanoparticles,Peptides and proteins,Quantum dots Get e-Alerts

The objective of this study was to evaluate the distribution of silver nanoparticles (NPs) in pregnant mice and their developing embryos. Silver NPs (average diameter 50 nm) were intravenously injected into pregnant CD-1 mice on gestation days (GDs) 7, 8, and 9 at dose levels of 0, 35, or 66 μg Ag/mouse. Mice were euthanised on GD10, and tissue samples were collected and analysed for silver content. Compared with control animals injected with citrate buffer vehicle, silver content was significantly increased (p < 0.05) in nearly all tissues from silver NP-treated mice. Silver accumulation was significantly higher in liver, spleen, lung, tail (injection site), visceral yolk sac, and endometrium compared with other organs from silver NP-treated mice. Furthermore, silver NPs were identified in vesicles in endodermal cells of the visceral yolk sac. In summary, the results demonstrated that silver NPs distributed to most maternal organs, extra-embryonic tissues, and embryos, but did not accumulate significantly in embryos.

A critical metrology issue for pharmaceutical industries is the application of analytical techniques for the characterization of drug delivery systems to address interrelationships between processing, structure, and drug release. In this study, cast coatings were formed from solutions of poly(styrene-b-isobutylene-b-styrene) (SIBS) and tetracycline in tetrahydrofuran (THF). These coatings were characterized by several imaging modalities, including time-of-flight secondary ion mass spectrometry (TOF-SIMS) for chemical imaging and analysis, atomic force microscopy (AFM) for determination of surface structure and morphology, and laser scanning confocal microscopy (LSCM), which was used to characterize the three-dimensional structure beneath the surface. The results showed phase separation between the drug and copolymer regions. The size of the tetracycline phase in the polymer matrix ranged from hundreds of nanometers to tens of microns, depending on coating composition. The mass of drug released was not found to be proportional to drug loading, because the size and spatial distribution of the drug phase varied with drug loading and solvent evaporation rate, which in turn affected the amount of drug released.

With the advent of nanotechnology, silver nanoparticles increasingly are being used in coatings, especially in medical device applications, to capitalize on their antimicrobial properties. The attractiveness of nanoparticulate silver systems is the expected increased antimicrobial efficacy relative to their bulk counterparts, which may be attributed to an increased silver ion (Ag+) solubility, and hence availability, that arises from capillarity effects in small, nanometer-sized particles. However, a change of the material upon which the antimicrobial nanoparticulate silver is deposited (herein called "substrate") may affect the availability of Ag+ ions and the intended efficacy of the device. We utilize both theory and experiment to determine the effect of substrate on ion release from silver particles in electrochemical environments and find that substrate surface charge, chemical reactivity or affinity of the surface for Ag+ ions, and wettability of the surface all affect availability of Ag+ ions, and hence antimicrobial efficacy. It is also observed that with time of exposure to deionized water, Ag+ ion release increases to a maximum value at 5 min before decreasing to undetectable levels, which is attributed to coarsening of the nanoparticles, and which subsequently reduces the solubility and availability of Ag+ ions. This coarsening phenomenon is also predicted by the theoretical considerations and has been confirmed experimentally by transmission electron microscopy.

Background: Transarterial chemoembolization (TACE) is the standard first-line therapy for intermediate-stage hepatocellular carcinoma (HCC). However, no latent-classing indices, concerning repeat conventional TACE or switching to another treatment, have been incorporated into the guidelines. Methods: The unsupervised latent class modeling was applied to identify subphenotypes using the clinical and medical imaging data of 1517 HCC patients after the first TACE from four hospitals (derivation cohort: 597 cases; validation cohort: 920 cases); modeling was conducted independently in each cohort. We then explored the relationship of subphenotypes with clinical outcomes in both cohorts and response to treatment strategies after the first TACE in the derivation cohort. Results: Independent latent class models suggested that a three-class model was optimal for both cohorts. In both cohorts, we identified a TACE-refractory subphenotype (Phenotype 1: PS score 1, stage progress, more intrahepatic lesions, and new intrahepatic lesions), TACE-responsive subphenotype (Phenotype 3: PS score 0, No intrahepatic lesions and new intrahepatic lesions), compared to TACE-intermediate subphenotype (Phenotype 2). Compared to Phenotype 1 or 2, patients in Phenotype 3 had significantly lower 3-month or 3-year mortality (all P<0.001). In the derivation cohort, the effects of treatment strategy (surgery/ablation vs. repeat TACE vs. stop TACE) differed significantly in phenotype 2 but not in phenotype 3 (P=0.721 for interaction). Conclusions: Latent class models identified three subphenotypes for HCC after the first TACE treatment. Differences were significant in clinical outcome and response to treatment strategy after the first TACE among three subphenotypes.

There are a variety of well-developed analytical tools that have been successfully applied to unmodified/native nanoparticle (NP) characterization. The question addressed here is whether these same technologies can be used for the analysis of NP-bioconjugates, given the added complexity of their composite structure, and if they can provide the additional information sought by the user. The short answer is, of course, yes, but as found with unmodified NP analysis, it is fair to say that no one technique can provide a complete characterization of engineered NP-bioconjugates. Rather, a combination of techniques must be used to characterize the many metrics associated with the NP scaffold itself and also the overall NP-bioconjugate assembly. The aim of this chapter is to provide the reader with an overview of the general principles and potential information available from each technology, along with some pertinent examples which highlight both the potential advantages and/or drawbacks of each particular technique.

Silver is one of the oldest known natural antimicrobial materials, the active form being the Ag+ ion, which disrupts critical cell functions in bacteria. Reducing the size of silver particles to the nanoscale regime increases the surface area and hence the availability of silver ions, thereby enhancing their potential antimicrobial efficacy relative to their bulk counterparts. Nanoparticulate silver systems have been used as antimicrobial agents for medical device applications such as bandages, wound dressings, surgical masks, endotracheal tubes, and catheters. However the surface onto which the silver nanoparticles are deposited will impact the availability of Ag+ ions due to the chemistry of the substrate surface and its affinity for silver ions. The effect of substrate material on the efficacy of nanoparticulate silver will be discussed, along with the implications of materials selection in medical device applications.