Detecting the shape of anisotropic gold nanoparticles in dispersion with single particle extinction and scattering.

The shape and size of nanoparticles are important parameters affecting their biodistribution, bioactivity, and toxicity. The high-throughput characterisation of the nanoparticle shape in dispersion is a fundamental prerequisite for realistic in vitro and in vivo evaluation, however, with routinely available bench-top optical characterisation techniques, it remains a challenging task. Herein, we demonstrate the efficacy of a single particle extinction and scattering (SPES) technique for the in situ detection of the shape of nanoparticles in dispersion, applied to a small library of anisotropic gold particles, with a potential development for in-line detection. The use of SPES paves the way to the routine quantitative analysis of nanoparticles dispersed in biologically relevant fluids, which is of importance for the nanosafety assessment and any in vitro and in vivo administration of nanomaterials.

An environmental route of exposure affects the formation of nanoparticle coronas in blood plasma.

UNLABELLED: Nanoparticles (NPs) in contact with biological fluids become covered by a tightly bound layer of proteins, the "protein corona", and it is largely accepted that this corona gives a new identity to NPs in biological milieu. We here consider the exposing scenario of NPs through an environmental route exemplified by the use of hydrophobins, highly adhesive proteins that are secreted into the environment in large quantities by fungi. HFBII of Trichoderma reesei has been used as a model protein and we have shown strong binding to polystyrene NPs of different sizes and surface groups. Hydrophobin coated NPs are shown to strongly increase the stability and the dispersion when exposed to human plasma compared to pristine ones particles. It is also shown that the presence of hydrophobin on the NPs results in an attenuated protein corona formation, in a different corona composition, and we also show that hydrophobin remained strongly associated to the NPs in competition with plasma proteins. As a conclusion we therefore suggest that the route of exposure of nanoparticles strongly affects their surface properties and their possible physiological behavior. SIGNIFICANCE: This work shows how a self-assembling protein, class II hydrophobin HFBII, with interesting biocompatible coating properties, strongly adsorbs on polystyrene NPs. HFBII is also shown to reduce aggregation of the NPs in human plasma which can increase their bioavailability with potential use in biomedical applications. The results here are also of significance for understanding possible interactions of NPs with living organisms. Hydrophobins are secreted in large quantities into the environment by fungi and this work shows how the biological environment of NPs determines the surface and colloidal properties of the particles by forming a protein corona, and that the history of the particle environment, here simulated with hydrophobin exposure, affects both plasma protein corona formation and dispersion behavior. This work thus simulates how alternative exposure routes affect nanoparticle properties, important in understanding the biological fate of NPs.

Characterization of the bionano interface and mapping extrinsic interactions of the corona of nanomaterials.

Nanoparticles in physiological environments are known to selectively adsorb proteins and other biomolecules forming a tightly bound biomolecular 'corona' on their surface. Where the exchange times of the proteins are sufficiently long, it is believed that the protein corona constitutes the particle identity in biological milieu. Here we show that proteins in the corona retain their functional characteristics and can specifically bind to cognate proteins on arrays of thousands of immobilised human proteins. The biological identity of the nanomaterial is seen to be specific to the blood plasma concentration in which they are exposed. We show that the resulting in situ nanoparticle interactome is dependent on the protein concentration in plasma, with the emergence of a small number of dominant protein-protein interactions. These interactions are those driven by proteins that are adsorbed onto the particle surface and whose binding epitopes are subsequently expressed or presented suitably on the particle surface. We suggest that, since specific tailored protein arrays for target systems and organs can be designed, their use may be an important element in an overall study of the biomolecular corona.

Evidence for immunomodulation and apoptotic processes induced by cationic polystyrene nanoparticles in the hemocytes of the marine bivalve Mytilus.

Polymeric nanoparticles can reach the marine environment from different sources as weathering of plastic debris and nanowaste. Nevertheless, few data are available on their fate and impact on marine biota. Polystyrene nanoparticles (PS NPs) can be considered as a model for studying the effects of nanoplastics in marine organisms: recent data on amino-modified PS NPs (PS-NH2) toxicity in sea urchin embryos underlined that marine invertebrates can be biological targets of nanoplastics. Cationic PS NPs have been shown to be toxic to mammalian cells, where they can induce apoptotic processes; however, no information is available on their effects and mechanisms of action in the cells of marine organisms. In this work, the effects of 50 nm PS-NH2 were investigated in the hemocytes of the marine bivalve Mytilus galloprovincialis. Hemocytes were exposed to different concentrations (1, 5, 50 µg/ml) of PS-NH2 suspension in ASW. Clear signs of cytoxicity were evident only at the highest concentrations (50 µg/ml). On the other hand, a dose dependent decrease in phagocytic activity and increase in lysozyme activity were observed. PS-NH2 NPs also stimulated increase in extracellular ROS (reactive oxygen species) and NO (nitric oxide) production, with maximal effects at lower concentrations. Moreover, at the highest concentration tested, PS-NH2 NPs induced apoptotic process, as evaluated by Flow cytometry (Annexin V binding and mitochondrial parameters). The results demonstrate that in marine invertebrates the immune function can represent a significant target for PS-NPs. Moreover, in Mytilus hemocytes, PS-NH2 NPs can act through mechanisms similar to those observed in mammalian cells. Further research is necessary on specific mechanisms of toxicity and cellular uptake of nanoplastics in order to assess their impact on marine biota.

A longitudinal study of oral ulcerative mucositis in bone marrow transplant recipients.

BACKGROUND: Few longitudinal studies have investigated the onset, duration, and resolution of ulcerative mucositis in bone marrow transplant recipients. This study prospectively followed a group of such patients on a daily basis to obtain data on the incidence of ulcerative mucositis, location and duration of lesions, severity with different conditioning regimens, and the relationship of such mucositis to the absolute neutrophil count. METHODS: Fifty-nine bone marrow transplant recipients on prophylactic acyclovir were examined daily for 26 days after marrow infusion, and all oral ulcerative lesions were recorded. RESULTS: Oral ulcers occurred in 76.3% of patients, began at a mean of 5 days after marrow infusion (day + 5), and lasted for a median of 6 days. More than 90% of patients showed complete resolution of ulcers on or before day + 15, and all showed resolution when the absolute neutrophil count was > 500 cells/ml. Persistence of ulcers was noticed in patients who had oral graft-versus-host disease and in some patients who initially developed more severe ulcerations. Ninety-six percent of ulcers were located on nonkeratinized mucosa. CONCLUSIONS: Ulcerative mucositis occurs in about 75% of bone marrow transplant recipients in the absence of herpes simplex virus infection. Most lesions occur on nonkeratinized mucosae which are vulnerable to trauma, especially if such mucosae are rendered atrophic by conditioning regimens. Oral ulcers may persist beyond day + 15 and after recovery of the neutrophil count in patients who initially develop more severe ulcerations or in patients who develop graft-versus-host disease.

Assessment of the need for treatment of postendodontic asymptomatic periapical radiolucencies in bone marrow transplant recipients.

Oral screening and treatment of existing oral disease before bone marrow transplantation have been reported to decrease the incidence of infectious complications during bone marrow transplantation. Information about the adverse sequelae of specific preexisting oral diseases during bone marrow transplantation is lacking. The presence of postendodontic periapical radiolucencies may suggest recurrent or latent infection. The purpose of this study was to compare the effect of endodontic treatment with nontreatment of asymptomatic postendodontic periapical radiolucencies on the frequency of infectious oral complications during bone marrow transplantation. The records of 276 patients undergoing bone marrow transplantation examined between July 1988 and June 1991 were reviewed retrospectively. Twenty-three postendodontic periapical radiolucencies were identified in 8 women and 15 men. The mean age of patients was 41 years (range, 25 to 58 years). Fourteen of the lesions were untreated, and nine were treated before bone marrow transplantation. When outcomes of transplant complications were compared, neither increased systemic infection as measured by neutropenic days febrile nor local oral infectious complications were significantly different. These results suggest that nontreatment of asymptomatic postendodontic periapical radiolucencies does not increase the incidence of infectious complications during bone marrow transplantation.

Oral diseases in older adults.

In the case presented, a 65-year-old man with multiple dental, medical, and social problems benefited from interdisciplinary assessment and treatment. Despite his poor oral-health status and oral-health behaviors upon admission, patient education and dental therapy resulted in improved daily oral hygiene, elimination of oral diseases, and improved oral function. The overall quality of life of any individual, particularly an older one, can be enhanced through oral-disease prevention, health promotion, and, when indicated, dental therapy. This patient was treated in a hospital environment with a well-established team approach to geriatric care. However, regardless of the care setting, the physician can play a key role in improving the oral health status and quality of life of older adults by including an oral screening examination as part of the periodic comprehensive geriatric assessment, recognizing oral pathology, requesting dental consultations and encouraging appropriate dental service utilization.