One method of delivering drugs is with the use of metal colloids. Often done by using silver and gold ions, this method is favored because of its long history and relative stability. Note here that when I talk about stability in nanoparticles, it doesn’t always mean a positive characteristic, because more stability can mean more toxicity without the body breaking down the particle.
These colloidal gold particles are made by first separating the ions and then supersaturating it, allowing for precipitation to form. Finally it is broken down to uniform particle size for delivery. Of course the steps are not as simple as I described, but it is the general schematic.
One thing that makes using metal ions like this stand out is the simple characteristics of metal. First it allows for conduction of electricity, which many other nanoparticles can’t do… and also it allows for scattering of light, allowing us to take beautiful pictures like the one above without having to use fluorescent tags.