Colloids are ubiquitous, present all around us, and they have been of technological importance for centuries. The concept of nanoscale modification of colloid particles is an emerging field in materials science, chemistry, and physics. The impetus is the design and construction of new classes of colloids with tailored properties that can ultimately be exploited to address interests in modern nanoscience and nanotechnology. I assume that the article has drawn considerable attention because it provides a rather comprehensive overview of strategies that permit the modification of colloid particles, highlighting the benefits of each approach, and the current and future applications of the processed particles.

The article describes a number of recent methodologies for coating colloid particles. One of these involves the combination of the layer-by-layer deposition of charged species and colloid templating. This approach is highly versatile—it can be applied to a whole range of core particles and coating materials—and, therefore, is likely to be useful to others.

It permits the coating of a range of particles, such as polymers, inorganic crystals or biological (colloids), with a variety of synthetic polymer or natural protein layers (as well as nanoparticles). Multiple coatings can be applied layer-by-layer, while still maintaining the integrity of the particles as colloids, and they can be given, (for example,) unique magnetic, optical, (mechanical) or catalytic properties. Recent work has shown that it can be applied to encapsulate biomaterials, construct multilayered drug delivery vehicles, prepare novel immunoparticles for diagnostic applications, and to fabricate ordered porous materials with tailored properties. On the whole, the method is of interest in areas ranging from the physical to the life sciences.

  Could you summarize the significance of your paper in layman's terms?

The review is significant because it summarizes a broad range of approaches for preparing coated particles in the nanometer to the micrometer size range. These particles often exhibit enhanced properties compared with their individual component counterparts. An important aspect is that the article highlights the advantages and disadvantages of the different approaches, thereby providing details that are necessary when preparing designer particles. On the whole, the significance lies in the article being likely to inspire multidisciplinary research on the "particle edge" well into the new millennium, thus rapidly expanding the technological application of colloids.

Frank Caruso
Group Leader, Nanostructered Materials,
Max Planck Institute of Colloids and Interfaces,
D-14414 Pottsdam, Germany