In this last area, gold nanoparticles are being developed to provide sophisticated delivery mechanisms for a range of conventional and novel treatments, from oral insulin administration to targeted cancer drugs and DNA conjugates for advanced gene therapies.Īs with all particulate therapeutics, the pharmacokinetic properties of colloidal gold conjugates, such as bioavailability and clinical efficacy, are strongly influenced by particle size. These unique physical properties are currently being exploited for a variety of biomedical applications, including their use as imaging probes, diagnostic agents, and for advanced drug delivery. Furthermore, gold nanoparticles suspended within aqueous media form negatively charged ions that have a strong affinity for biological macromolecules, such as proteins and antibodies, which form biological ligands around the ion. Its chemical and physical inertness ensure the material is toxicologically safe in vivo, while its fine size allows particles to cross a cell membrane without harming the cell.
Beyond these conventional therapies, modern interest in gold lies in its colloidal form.Ī number of properties of colloidal gold make it well-suited for nanomaterial-based clinical applications. Fast forward another 100 years, and gold salts are now routinely administered for the treatment and management of rheumatic arthritis. However, it wasn’t until the 18th century that the antibacterial properties of gold cyano salts were discovered. Experimental data are presented to illustrate how advanced Dynamic Light Scattering (DLS) techniques deliver these measurements for colloidal gold in the nanosized and sub-nanosized ranges.ĪLL THAT GLITTERS: A BRIEF HISTORY OF GOLD THERAPYīelief in the therapeutic properties of gold can be traced back to ancient times. This article explores the importance of particle size in biomedical nanotechnology. In this way, gold nanoparticles are set to play an important role as a platform for novel intracellular delivery vehicles and controlling nanoparticle size throughout the formulation process, which is crucial to defining this functionality.
Taking drug delivery as an example, manipulation of the unique chemical, physical, and electronic properties of colloidal gold enables researchers to develop drug-nanoparticle conjugates for targeted drug delivery, improving a drug’s biodistribution and pharmacokinetics within specific biological targets, such as diseased tissue or cancerous cells. Nanosized colloidal gold has great potential in multiple therapeutic and biotechnology applications. In commercial terms, the result of this carefully fostered research is that by 2015, the market for biomedical nanotechnology is expected to exceed $70 billion.1 In practical terms, this suggests a potentially transformative shift in the way diseases are targeted and treated. There appears to be very good reproducibility of the colloidal silver particle size and number concentrations between the bottles of the materials tested by Plymouth University.Today, the maturation of a decade’s worth of investment into nanotechnology is seeing nanomedical materials steadily emerge into clinical and medical practice. The particle number concentration was 10-11 x 108 particles/ml almost identical to the previous batch at 11-12 x 108 particles/ml. The mean diameter (35 nm) was also close to the previous bottles (34.5 nm). Particles were detected in the bottle (Table 1), and the median size was around 29 nm (close to the 32 nm measured in the previous batch). “Nanoparticle tracking analysis was used to determine the size distribution of the particles in the bottle, using the same methodology as the previous batch that was analysed. Particle size distribution in the dispersions Cumulative percentage undersize is shown in red (%). The concentration at each size category (nm) in shown as 106 particles/ml.
Size distribution of colloidal silver determined using nanoparticle tracking analysis (Nanosight NTA 2.2). Note the range of sizes with a few percent of particles as small as 10 nm and as large as around 90 nm for the largest aggregates measured in the samples. An example plot of the particle size distribution as hydrodynamic diameter is shown (Figure 2). Mean and median particle sizes (hydrodynamic diameter) determined by NTA.īased on these direct measurements of hydrodynamic diameter, the volume-weighted median for particles of 32 nm diameter would be the particle number concentration (12×108 particles/ml) times the volume of a single particle (i.e., 4/3Pi r3) or approximately (200 nm3/ml).