Introduction 4708 2. Peptides and Silver 4709 2.1. Silver Binding to Amino Acids and Peptides 4709 2.1.1. Silver Binding to Amino Acids − Theory 4709 2.1.2. Silver Binding to Amino Acids − Experiment 4711 2.1.3. Silver Binding to Peptides 4711 2.2. Natural Peptides Involved in Metal Detoxification 4714 2.3. Peptides for the Formation of Silver Nanostructures 4716 2.3.1. Biomineralization of Silver by Means of Peptides 4716 2.3.2. Peptides as Structure-Determining Scaffolds in the Synthesis of Silver Nanostructures 4721 3. Bacteria and Silver 4722 3.1. Antimicrobial Properties of Silver-Containing Compounds 4722 3.1.1. Interactions with the Bacterial Cell Wall 4722 3.1.2. Interactions with DNA, Enzymes, and Membrane Proteins 4724 3.1.3. Generation of Reactive Oxygen Species 4725 3.2. Bacterial Resistance Mechanisms against Ag(I) 4726 3.2.1. Accumulation and Storage-Based Mechanism 4726 3.2.2. Efflux Pump-Based Mechanism 4727 3.3. Synthesis of Silver Nanoparticles by Means of Bacteria 4728 4. Silver-Based Biomaterials in the Medical Field 4730 4.1. Types of Silver-Containing Biomaterials 4731 4.1.1. Metallic Silver Coatings and Silver's Antimicrobial Efficiency 4731 4.1.2. Silver-Containing Nanocomposites 4732 4.1.3. Silver-Containing Polymers 4732 4.1.4. Surface Modification with Ionic Silver Compounds 4734 4.1.5. Hybrid Silver Materials − Synergistic Effects 4734 4.2. Deposition Processes 4735 4.3. Mechanical Properties 4736 5. Biocompatibility of Silver 4737 5.1. General Routes of Silver Exposure 4737 5.2. Exposure to Silver-Containing Medical Products 4737 5.2.1. Dermal Contact: Burn Wound Dressings 4737 5.2.2. Bone Contact: Orthopedic and Dental Implants and Bone-Filling Products 4738 5.2.3. Blood Contact: Implants Introduced into the Vascular System 4739 5.3. Effects of Silver Exposure on Tissues and Organs 4739 5.3.1. Acute and Chronic Toxicity of Silver 4740 5.3.2. Tissue and Organ Damages 4740 5.3.3. Cellular Uptake of Silver 4741 5.4. Toxic Effects of Silver Nanoparticles 4741 5.5. Silver Detoxification 4742 5.5.1. Sequestration of Silver Ions 4742 5.5.2. Silver Ion Transport by ATPase P-type Efflux Pumps 4743 6. Conflicting Evidence 4744 7. Conclusions 4744 Author Information 4744 Corresponding Author 4744 Notes 4744 Biographies 4745 Acknowledgments 4746 References 4746

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Nanoceria (cerium oxide nanoparticles) toxicity is currently a concern because of its use in motor vehicles in order to reduce carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons in exhaust gases. In addition, many questions arise with respect to its biomedical applications exploiting its potential to protect cells against irradiation and oxidative stress. Indeed, toxicology studies on nanoceria report results that seem contradictory, demonstrating toxic effects in some studies, protective effects in others, and sometimes little or no effect at all. The variability in the experimental setups and particle characterization makes these studies difficult to compare and the toxicity of newly developed nanoceria materials challenging to predict. This microreview aims to compare the toxicity of nanoceria in terms of preparation method, particle size, concentration, host organism, and exposure method.

A better characterization of nanometer-thick organic layers (monolayers) as used for engineering surface properties, biosensing, nanomedicine, and smart materials will widen their application. The aim of this study was to develop direct analysis in real time high-resolution mass spectrometry (DART-HRMS) into a new and complementary analytical tool for characterizing organic monolayers. To assess the scope and formulate general interpretation rules, DART-HRMS was used to analyze a diverse set of monolayers having different chemistries (amides, esters, amines, acids, alcohols, alkanes, ethers, thioethers, polymers, sugars) on five different substrates (Si, Si3N4, glass, Al2O3, Au). The substrate did not play a major role except in the case of gold, for which breaking of the weak Au-S bond that tethers the monolayer to the surface, was observed. For monolayers with stronger covalent interfacial bonds, fragmentation around terminal groups was found. For ester and amide-terminated monolayers, in situ hydrolysis during DART resulted in the detection of ions characteristic of the terminal groups (alcohol, amine, carboxylic acid). For ether and thioether-terminated layers, scission of C-O or C-S bonds also led to the release of the terminal part of the monolayer in a predictable manner. Only the spectra of alkane monolayers could not be interpreted. DART-HRMS allowed for the analysis of and distinction between monolayers containing biologically relevant mono or disaccharides. Overall, DART-HRMS is a promising surface analysis technique that combines detailed structural information on nanomaterials and ultrathin films with fast analyses under ambient conditions.

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