The effects of engineered coatings and natural organic matter on nanoparticle aggregation

In order to better predict the aggregation state of nanomaterials, the factors that influence aggregation must be understood. The combined effects of natural and engineered coatings have been shown to factor into nanoparticle aggregation behavior in preliminary research. In this study, aggregation behaviors of gold nanoparticles with two different engineered coatings were investigated in the presence of the monovalent electrolyte KCl and the divalent electrolyte CaCl₂. Aggregation studies were conducted using dynamic light scattering to determine the relative stability of the NMs in environments of varying ionic strength in the absence and presence of Suwannee River Natural Organic Matter (SRNOM). Coatings which provided primarily electrostatic stabilization were found to adhere closely to DLVO theory, while coatings which provided steric stability inhibited aggregation over a wide range of ionic strengths for both electrolytes. The presence of SRNOM was found to provide some electrostatic stability in the presence of KCl, but appeared to form agglomerates with calcium ions, especially at higher SRNOM concentrations

Effects of Natural Organic Matter Type and Concentration on the Aggregation of Citrate-Stabilized Gold Nanoparticles

The aggregation of 12 nm citrate-stabilized gold nanoparticles (cit-AuNPs) in the presence of four different natural organic matter (NOM) isolates and a monovalent electrolyte (KCl) was evaluated using time-resolved dynamic light scattering. All four NOM isolates stabilized the cit-AuNPs with respect to aggregation. However, specific effects varied among the different NOM isolates. At pH = 6 in 80 mM KCl, low concentrations (<0.25 mg C/L) of large molecular weight Suwannee River Humic Acid (SRHA) was required to stabilize cit-AuNPs, while larger concentrations (>2 mg C/L) of smaller Suwannee River Fulvic Acid (SRFA) were necessary at the same ionic strength. Suwannee River NOM (SRNOM) which contains both SRHA and SRFA behaved in a manner intermediate between the two. Pony Lake Fulvic Acid (PLFA), an autochthonous NOM isolate, provided substantial stability at low concentrations, yet aggregation was induced at NOM concentrations > 2 mg C/L, a trend that is hypothesized to be the result of favourable hydrophobic interactions between coated particles induced at increased surface coverage. For all NOM isolates, it appears that NOM adsorption or conformational changes at the AuNP surfaces result in significant increases in the hydrodynamic diameter that aren’t attributable to NP-NP aggregation

Direct monitoring of single-cell response to biomaterials by Raman spectroscopy

There is continued focus on the development of new biomaterials and associated biological testing methods needed to reduce the time taken for their entry to clinical use. The application of Raman spectroscopy to the study of individual cells that have been in contact with biomaterials offers enhanced in vitro information in a potentially non-destructive testing regime. The work presented here reports the Raman spectral analysis of discreet U-2 OS bone cells after exposure to hydroxyapatite (HA) coated titanium (Ti) substrates in both the as-deposited and thermally annealed states. These data show that cells that were in contact with the bioactive HA surface for 7 days had spectral markers similar to those cultured on the Ti substrate control for the same period. However, the spectral features for those cells that were in contact with the annealed HA surface had indicators of significant differentiation at day 21 while cells on the as-deposited surface did not show these Raman changes until day 28. The cells adhered to pristine Ti control surface showed no spectral changes at any of the timepoints studied. The validity of these spectroscopic results has been confirmed using data from standard in vitro cell viability, adhesion, and proliferation assays over the same 28-day culture period. In this case, cell maturation was evidenced by the formation of natural bone apatite, which precipitated intracellularly for cells exposed to both types of HA-coated Ti at 21 and 28 days, respectively. The properties of the intracellular apatite were markedly different from that of the synthetic HA used to coat the Ti substrate with an average particle size of 230 nm, a crystalline-like shape and Ca/P ratio of 1.63 ± 0.5 as determined by SEM-EDX analysis. By comparison, the synthetic HA particles used as a control had an average size of 372 nm and were more-rounded in shape with a Ca/P ratio of 0.8 by XPS analysis and 1.28 by SEM-EDX analysis. This study shows that Raman spectroscopy can be employed to monitor single U-2 OS cell response to biomaterials that promote cell maturation towards de novo bone thereby offering a label-free in vitro testing method that allows for non-destructive analyses. [Image: see text

The Opportunistic Pathogen Propionibacterium acnes: Insights into Typing, Human Disease, Clonal Diversification and CAMP Factor Evolution

We previously described a Multilocus Sequence Typing (MLST) scheme based on eight genes that facilitates population genetic and evolutionary analysis of P. acnes. While MLST is a portable method for unambiguous typing of bacteria, it is expensive and labour intensive. Against this background, we now describe a refined version of this scheme based on two housekeeping (aroE; guaA) and two putative virulence (tly; camp2) genes (MLST4) that correctly predicted the phylogroup (IA1, IA2, IB, IC, II, III), clonal complex (CC) and sequence type (ST) (novel or described) status for 91% isolates (n = 372) via cross-referencing of the four gene allelic profiles to the full eight gene versions available in the MLST database (http:// pubmlst.org/pacnes/). Even in the small number of cases where specific STs were not completely resolved, the MLST4 method still correctly determined phylogroup and CC membership. Examination of nucleotide changes within all the MLST loci provides evidence that point mutations generate new alleles approximately 1.5 times as frequently as recombination; although the latter still plays an important role in the bacterium’s evolution. The secreted/cell-associated ‘virulence’ factors tly and camp2 show no clear evidence of episodic or pervasive positive selection and have diversified at a rate similar to housekeeping loci. The co-evolution of these genes with the core genome might also indicate a role in commensal/normal existence constraining their diversity and preventing their loss from the P. acnes population. The possibility that members of the expanded CAMP factor protein family, including camp2, may have been lost from other propionibacteria, but not P. acnes, would further argue for a possible role in niche/host adaption leading to their retention within the genome. These evolutionary insights may prove important for discussions surrounding camp2 as an immunotherapy target for acne, and the effect such treatments may have on commensal lineages

Efficacy of intra-articular hyaluronan (Synvisc®) for the treatment of osteoarthritis affecting the first metatarsophalangeal joint of the foot (hallux limitus): study protocol for a randomised placebo controlled trial

<p>Abstract</p> <p>Background</p> <p>Osteoarthritis of the first metatarsophalangeal joint (MPJ) of the foot, termed <it>hallux limitus</it>, is common and painful. Numerous non-surgical interventions have been proposed for this disorder, however there is limited evidence for their efficacy. Intra-articular injections of hyaluronan have shown beneficial effects in case-series and clinical trials for the treatment of osteoarthritis of the first metatarsophalangeal joint. However, no study has evaluated the efficacy of this form of treatment using a randomised placebo controlled trial. This article describes the design of a randomised placebo controlled trial to evaluate the efficacy of intra-articular hyaluronan (Synvisc^®) to reduce pain and improve function in people with hallux limitus.</p> <p>Methods</p> <p>One hundred and fifty community-dwelling men and women aged 18 years and over with hallux limitus (who satisfy inclusion and exclusion criteria) will be recruited.</p> <p>Participants will be randomised, using a computer-generated random number sequence, to receive a single intra-articular injection of up to 1 ml hyaluronan (Synvisc^®) or sterile saline (placebo) into the first MPJ. The injections will be performed by an interventional radiologist using fluoroscopy to ensure accurate deposition of the hyaluronan in the joint. Participants will be given the option of a second and final intra-articular injection (of Synvisc^®or sterile saline according to the treatment group they are in) either 1 or 3 months post-treatment if there is no improvement in pain and the participant has not experienced severe adverse effects after the first injection. The primary outcome measures will be the pain and function subscales of the Foot Health Status Questionnaire. The secondary outcome measures will be pain at the first MPJ (during walking and at rest), stiffness at the first MPJ, passive non-weightbearing dorsiflexion of the first MPJ, plantar flexion strength of the toe-flexors of the hallux, global satisfaction with the treatment, health-related quality of life (assessed using the Short-Form-36 version two questionnaire), magnitude of symptom change, use of pain-relieving medication and changes in dynamic plantar pressure distribution (maximum force and peak pressure) during walking. Data will be collected at baseline, then 1, 3 and 6 months post-treatment. Data will be analysed using the intention to treat principle.</p> <p>Discussion</p> <p>This study is the first randomised placebo controlled trial to evaluate the efficacy of intra-articular hyaluronan (Synvisc^®) for the treatment of osteoarthritis of the first MPJ (hallux limitus). The study has been pragmatically designed to ensure that the study findings can be implemented into clinical practice if this form of treatment is found to be an effective treatment strategy.</p> <p>Trial registration</p> <p>Australian New Zealand Clinical Trials Registry: ACTRN12607000654459</p

Land Rehabilitation and Maintenance Equipment Sources

Military training can often be destructive to the environment. Environmental impacts associated with heavy training include soil compaction, soil erosion, siltation of waterways and wetlands, increased threat of flooding, loss of wildlife habitat, declining biodiversity, and invasion by noxious weeds. Planning and implementing land rehabilitation projects generally involves some soil movement, establishment of vegetation, stabilization and hardening of sites, etc. Procurement of appropriate heavy equipment and other specialized equipment is sometimes a difficult task that involves obtaining multiple vendors, especially when procuring equipment for rental, lease, or purchase. This report and associated database were created to help land managers easily identify and obtain potential vendors for the equipment needed for land rehabilitation projects. This report includes a comprehensive and up-to-date list of heavy equipment vendors within the United States, primarily for rental or leasing purposes, which includes vendors of construction, agriculture, and other equipment needed for erosion control, and land rehabilitation and maintenance. Volume I of this report lists vendors located within 100 miles of Army installations, and National vendors. Volume II lists all vendors state-bystate

Sources of Plant Materials for Land Rehabilitation

Military training often results in environmental degradation that has negative impacts on future training missions. The U.S. Army Construction Engineering Research Laboratory (CERL) conceptualized the Army’s Integrated Training Area Management (ITAM) program in response to the concerns expressed by military land managers and trainers over the declining condition of training and testing lands. ITAM has evolved to include land condition and trend analysis (LCTA), environmental awareness (EA), training requirements integration (TRI), and land rehabilitation and maintenance (LRAM). The need for LRAM has increased dramatically over the past decade. Among the many difficulties faced in planning and implementing a land rehabilitation project is procurement of appropriate plant materials for revegetation of damaged lands. To satisfy government procurement requirements and ensure a fair and reasonable price for materials, it is usually necessary to identify and solicit bids from multiple vendors. Moreover, there is an increasing emphasis on the use of locally endemic or adapted plant species. These factors increase the demand to identify multiple commercial sources of regional or local sources of plant materials. This research compiled a comprehensive, current list of plant material vendors, including vendors of trees, shrubs, grasses, wild-flowers, and wetland plants