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. hard sphere, globular, dendrimer, chain stiffness, and degree of branching).Today, the maturation of a decade’s worth of investment into nanotechnology is seeing nanomedical materials steadily emerge into clinical and medical practice. Hydrodynamic sizes are more easily measured than radii of gyration and can be measured over a wider range of sizes. The conversion from hydrodynamic radius to radius of gyration is a function of chain architecture (including questions of random coil vs. The hydrodynamic radius is not the same as the radius of gyration. Radius calculations are the same except for a factor of two.Īlso, a note to those interested in polymer size. That is, the determined particle size is the size of a sphere that diffuses the way as your particle.įor those who work with protein sizing and other areas where hydrodynamic radius is more commonly used, note that the development here is around diameter. Finally, and most importantly, it reminds the analyst that the particle size determined by dynamic light scattering is the hydrodynamic size. Temperature is even more important due to the viscosity term since viscosity is a stiff function of temperature. The first is that sample temperature is important, at it appears directly in the equation. However, the equation does serve as important reminder about a few points. The calculations are handled by instrument software. T is thermodynamic temperature (we control this).k B is Boltzmann’s constant (we know this).D t is the translational diffusion coefficient (we find this by dynamic light scattering).D h is the hydrodynamic diameter (this is the goal: particle size!).
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