Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

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Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

This review focuses on the synthesis, protection, functionalization, and application of magnetic nanoparticles, as well as the magnetic properties of nanostructured systems. Substantial progress in the size and shape control of magnetic nanoparticles has been made by developing methods such as co-precipitation, thermal decomposition and/or reduction, micelle synthesis, and hydrothermal synthesis. A major challenge still is protection against corrosion, and therefore suitable protection strategies will be emphasized, for example, surfactant/polymer coating, silica coating and carbon coating of magnetic nanoparticles or embedding them in a matrix/support. Properly protected magnetic nanoparticles can be used as building blocks for the fabrication of various functional systems, and their application in catalysis and biotechnology will be briefly reviewed. Finally, some future trends and perspectives in these research areas will be outlined.

Magnetic nanoparticles: Synthesis, protection, functionalization, and application

1. Introduction 20642. Synthesis of Magnetic Nanoparticles 20662.1. Classical Synthesis by Coprecipitation 20662.2. Reactions in Constrained Environments 20682.3. Hydrothermal and High-TemperatureReactions20692.4. Sol-Gel Reactions 20702.5. Polyol Methods 20712.6. Flow Injection Syntheses 20712.7. Electrochemical Methods 20712.8. Aerosol/Vapor Methods 20712.9. Sonolysis 20723. Stabilization of Magnetic Particles 20723.1. Monomeric Stabilizers 20723.1.1. Carboxylates 20733.1.2. Phosphates 20733.2. Inorganic Materials 20733.2.1. Silica 20733.2.2. Gold 20743.3. Polymer Stabilizers 20743.3.1. Dextran 20743.3.2. Polyethylene Glycol (PEG) 20753.3.3. Polyvinyl Alcohol (PVA) 20753.3.4. Alginate 20753.3.5. Chitosan 20753.3.6. Other Polymers 20753.4. Other Strategies for Stabilization 20764. Methods of Vectorization of the Particles 20765. Structural and Physicochemical Characterization 20785.1. Size, Polydispersity, Shape, and SurfaceCharacterization20795.2. Structure of Ferro- or FerrimagneticNanoparticles20805.2.1. Ferro- and Ferrimagnetic Nanoparticles 20805.3. Use of Nanoparticles as Contrast Agents forMRI20825.3.1. High Anisotropy Model 20845.3.2. Small Crystal and Low Anisotropy EnergyLimit20855.3.3. Practical Interests of Magnetic NuclearRelaxation for the Characterization ofSuperparamagnetic Colloid20855.3.4. Relaxation of Agglomerated Systems 20856. Applications 20866.1. MRI: Cellular Labeling, Molecular Imaging(Inﬂammation, Apoptose, etc.)20866.2.

Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications

Biocompatible and biodegradable polymeric formulations are required in diverse biomedical applications. Among various polymers, polyaspartamide-derivative-based formulations are extensively employe...

Biomedical Applications of Functional Polyaspartamide-Based Materials

The family of carbon nanomaterials such as carbon nanoparticles, carbon nanotubes, graphene (atomically flat carbon), and graphene oxide (and reduced graphene oxide) is rapidly growing. Carbon nanomaterials are widely used in different electronic, optical, and biological applications. In this chapter their synthesis process, functionalization process for different medical and biological applications, and fundamental properties are described.

Different Synthesis Process of Carbon Nanomaterials for Biological Applications

A magnetic quantum dot (MQD) based cellular nanoprobe, composed of a magnetic oxide nanoparticle component and a quantum dot component, has been synthesized and used for both imaging and separation. The successful synthesis is based on a reverse micelle based polyacrylate coating in the presence of component nanoparticles, followed by their functionalization via conjugation chemistry.

Highly fluorescent magnetic quantum dot probe with superior colloidal stability

Nanotechnology is one of the most exciting disciplines that applied to improve the therapeutic indices by the carbon nanomaterials. Their unique physical and chemical properties make them interesting candidates of research in a wide range of areas including biological systems and different diseases. Recent research has been focused on exploring the potential of the carbon nanomaterials as a carrier or vehicle for intracellular transport of drugs, proteins, and targeted genes in vitro and in vivo. Several research groups are actively involved to find out a functional carbon nanomaterial carrier capable of transporting targeted drug molecules in animal models with least toxicity. This chapter is focused on carbon nanotubes, graphene, and carbon quantum dots, which appear to be promising agents for successful delivery of biomolecules in various animal models. But potential clinical implementations of carbon nanomaterials are still hampered by distinctive barriers such as poor bioavailability and intrinsic toxicity, which pose difficulties in tumor targeting and penetration as well as in improving therapeutic outcome. This chapter presents the progresses in the design and evaluation of closely related carbon nanomaterials for experimental cancer therapy and explores their implications in bringing nanomedicines into the clinics.

Application of Carbon-Based Nanomaterials as Drug and Gene Delivery Carrier

Autophagy is a cellular self-clearance process for maintaining regular cytoplasmic function, and modulation of autophagy can influence cytotoxicity, apoptosis, and clearance of toxic amyloid fibril...

Nikhil R. Jana

Papers

Biomedical Applications of Functional Polyaspartamide-Based Materials

Different Synthesis Process of Carbon Nanomaterials for Biological Applications

Highly fluorescent magnetic quantum dot probe with superior colloidal stability

Application of Carbon-Based Nanomaterials as Drug and Gene Delivery Carrier

Surface Chemistry- and Intracellular Trafficking-Dependent Autophagy Induction by Iron Oxide Nanoparticles