Accelerated In Vitro Oxidative Degradation Testing of Ultra-High Molecular Weight Polyethylene (UHMWPE).

Nonabsorbable polymers used in biomedical applications are assumed to be permanently stable based on short-term testing, but some may be susceptible to oxidative degradation over several years of implantation. Traditional in vitro oxidative degradation screenings employ hydrogen peroxide (HO) solutions. However, the inherent instability of HO can compromise the consistency of oxidative conditions, especially over extended periods and at elevated temperatures used for accelerated testing.

Influence of titanium nanoscale surface roughness on fibrinogen and albumin protein adsorption kinetics and platelet responses.

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.

Protein Adsorption on Chemically Modified Block Copolymer Nanodomains: Influence of Charge and Flow.

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.

Assessment of total silver and silver nanoparticle extraction from medical devices.

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).

Silver nanoparticles: correlating nanoparticle size and cellular uptake with genotoxicity.

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.

Different cytotoxicity responses to antimicrobial nanosilver coatings when comparing extract-based and direct-contact assays.

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 100 nm 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.

Assessment of titanium dioxide nanoparticle effects in bacteria: association, uptake, mutagenicity, co-mutagenicity and DNA repair inhibition.

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.

Distribution of silver nanoparticles in pregnant mice and developing embryos.

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.

The effect of substrate material on silver nanoparticle antimicrobial efficacy.

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.

Microstructure and elution of tetracycline from block copolymer coatings.

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 development of cement and concrete additive: based on xylonic acid derived via bioconversion of xylose.

The present work attempted to utilize xylose by converting it to an aldonic acid. In the present study, xylose was converted to xyloni acid by using commercial glucose oxidase enzyme, palladium catalysis, and microbial bioconversion. The enzyme conversion was successfully done using a commercial glucose oxidase.

The development of cement and concrete additive: based on xylonic acid derived via bioconversion of xylose.

The present work attempted to utilize xylose by converting it to an aldonic acid. In the present study, xylose was converted to xylonic acid by using commercial glucose oxidase enzyme, palladium catalysis, and microbial bioconversion. The enzyme conversion was successfully done using a commercial glucose oxidase.