The use of nanoparticles in some applications (i.e., nanomedical, nanofiltration or nanoelectronic) requires small-scale samples with well-known purities and composition. In addition, when nanoparticles are introduced into complex environments (e.g., biological fluids), the particle may become coated with matter, such as proteins or lipid layers. Many of todays analytical techniques are not able to address small scale samples of nanoparticles to determine purity and presence of surface coatings and purity. Through the use of an elevated temperature quartz crystal microbalance (QCM) method we call microscale thermogravimetric analysis, or micro-TGA, the nanoparticle purity, as well as the purity of any surface coatings of nanomaterials can be measured. Microscale thermogravimetric analysis is used to determine surface ligand coverage of gold nanoparticles and confirm the presence of a poly(ethylene glycol) coating on SiO2 nanoparticles. Results are compared to traditional analytical techniques to demonstrate reproducibility and validity of micro-TGA for determining the presence of nanoparticle surface coatings. Carbon nanotube samples are also analyzed and compared to conventional TGA. The results demonstrate micro-TGA is a valid method for quantitative determination of the coatings on nanoparticles, and in some cases, can provide purity and compositional data of the nanoparticles themselves.
Citation: Analytical Chemistry
Pub Type: Journals