The search for understanding the interactions of nanosized materials with living organisms is leading to the rapid development of key applications, including improved drug delivery by targeting nanoparticles, and resolution of the potential threat of nanotechnological devices to organisms and the environment. Unless they are specifically designed to avoid it, nanoparticles in contact with biological fluids are rapidly covered by a selected group of biomolecules to form a corona that interacts with biological systems. Here we review the basic concept of the nanoparticle corona and its structure and composition, and highlight how the properties of the corona may be linked to its biological impacts. We conclude with a critical assessment of the key problems that need to be resolved in the near future.

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Biomolecular coronas provide the biological identity of nanosized materials

We discuss in this review how the roughness of a solid impacts its wettability. We see in particular that both the apparent contact angle and the contact angle hysteresis can be dramatically affected by the presence of roughness. Owing to the development of refined methods for setting very well-controlled micro- or nanotextures on a solid, these effects are being exploited to induce novel wetting properties, such as spontaneous filmification, superhydrophobicity, superoleophobicity, and interfacial slip, that could not be achieved without roughness.

Wetting and Roughness

Bile salt biotransformations by human intestinal bacteria.

Nanomaterials (NMs) have gained prominence in technological advancements due to their tunable physical, chemical and biological properties with enhanced performance over their bulk counterparts. NMs are categorized depending on their size, composition, shape, and origin. The ability to predict the unique properties of NMs increases the value of each classification. Due to increased growth of production of NMs and their industrial applications, issues relating to toxicity are inevitable. The aim of this review is to compare synthetic (engineered) and naturally occurring nanoparticles (NPs) and nanostructured materials (NSMs) to identify their nanoscale properties and to define the specific knowledge gaps related to the risk assessment of NPs and NSMs in the environment. The review presents an overview of the history and classifications of NMs and gives an overview of the various sources of NPs and NSMs, from natural to synthetic, and their toxic effects towards mammalian cells and tissue. Additionally, the types of toxic reactions associated with NPs and NSMs and the regulations implemented by different countries to reduce the associated risks are also discussed.

/pdf/review-on-nanoparticles-and-nanostructured-materials-history-ukc67h8z6q.pdf

Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations.

Recent achievements in the construction of surfaces with special wettabilities, such as superhydrophobicity, superhydrophilicity, superoleophobicity, superoleophilicity, superamphiphilicity, superamphiphobicity, superhydrophobicity/superoleophilicity, and reversible switching between superhydrophobicity and superhydrophilicity, are presented. Particular attention is paid to superhydrophobic surfaces created via various methods and surfaces with reversible superhydrophobicity and superhydrophilicity that are driven by various kinds of external stimuli. The control of the surface micro-/nanostructure and the chemical composition is critical for these special properties. These surfaces with controllable wettability are of great importance for both fundamental research and practical applications.

Design and Creation of Superwetting/Antiwetting Surfaces

Research into extreme water-repellent surfaces began many decades ago, although it was only relatively recently that the term superhydrophobicity appeared in literature Here we review the work on the preparation of superhydrophobic surfaces, with focus on the different techniques used and how they have developed over the years, with particular focus on the last two years We discuss the origins of water-repellent surfaces, examining how size and shape of surface features are used to control surface characteristics, in particular how techniques have progressed to form multi-scaled roughness to mimic the lotus leaf effect There are notable differences in the terminology used to describe the varying properties of water-repellent surfaces, so we suggest some key definitions

Progess in superhydrophobic surface development.

Protein adhesion plays a major role in determining the biocompatibility of materials. The first stage of implant integration is the adhesion of protein followed by cell attachment. Surface modification of implants (surface chemistry and topography) to induce and control protein and cell adhesion is currently of great interest. This communication presents data on protein adsorption (bovine serum albumin and fibrinogen) onto model hydrophobic (CH3) and hydrophilic (OH) surfaces, investigated using a quartz crystal microbalance (QCM) and grazing angle infrared spectroscopy. Our data suggest that albumin undergoes adsorption via a single step whereas fibrinogen adsorption is a more complex, multistage process. Albumin has a stronger affinity toward the CH3 compared to OH terminated surface. In contrast, fibrinogen adheres more rapidly to both surfaces, having a slightly higher affinity toward the hydrophobic surface. Conformational assessment of the adsorbed proteins by grazing angle infrared spectroscopy (GA...

Interpretation of Protein Adsorption: Surface-Induced Conformational Changes

Protein adsorption behavior is at the heart of many of today's research fields including biotechnology and materials science. With understanding of protein-surface interactions, control over the conformation and orientation of immobilized species may ultimately allow tailor-made surfaces to be generated. In this contribution protein-surface interactions have been examined with particular focus on surface curvature with and without surface chemistry effects. Silica spheres with diameters in the range 15-165 nm with both hydrophilic and hydrophobic surface chemistries have been used as model substrates. Two proteins differing in size and shape, bovine serum albumin (BSA) and bovine fibrinogen (Fg), have been used in model studies of protein binding with detailed secondary structure analysis being performed using infrared spectroscopy (IR) on surface-bound proteins. Although trends in binding affinity and saturation values were similar for both proteins, albumin is increasingly less ordered on larger substrates, while fibrinogen, in contrast, loses secondary structure to a greater extent when adsorbing onto particles with high surface curvature. These effects are compounded by surface chemistry, with both proteins becoming more denatured on hydrophobic surfaces. Both surface chemistry and topography play key roles in determining the structure of the bound proteins. A model of the binding characteristics of these two proteins onto surfaces having differing curvature and chemistry is presented. We propose that properties of an adsorbed protein layer may be guided through careful consideration of surface structure, allowing the fabrication of materials/surface coatings with tailored bioactivity.

Surface tailoring for controlled protein adsorption: effect of topography at the nanometer scale and chemistry.

This review concerns the importance of length and time on physicochemical interactions between living tissue and biomaterials that occur on implantation. The review provides information on material host interactions, materials for medical applications and cell surface interactions, and then details the extent of knowledge concerning the role(s) that surface chemistry and topography play during the first stage of implant integration, namely protein adsorption. The key points are illustrated by data from model in vitro studies. Host implant interactions begin nanoseconds after first contact and from then on are in a state of flux due to protein adsorption, cell adhesion and physical and chemical alteration of the implanted material. The many questions concerning the conformational form and control of bound proteins and how this may impact on cell adhesion in the first instance and later on cell signalling and implant integration can be answered by systematic investigations using model materials. Only then we will be in a more informed position to design new materials for use in the body.

Paul D. Roach

Papers

Progess in superhydrophobic surface development.

Interpretation of Protein Adsorption: Surface-Induced Conformational Changes

Surface tailoring for controlled protein adsorption: effect of topography at the nanometer scale and chemistry.

Modern biomaterials: a review - bulk properties and implications of surface modifications.

Effects of spray drying conditions on the physicochemical and antioxidant properties of the Gac (Momordica cochinchinensis) fruit aril powder.