Rubyred mica sheets

To characterize the morphology of TeNPs, 5 µl aliquots of purified suspensions were diluted (10x) with 45 µl of ultrapure water and left to equilibrate at room temperature for 10 min. 10 µl of the diluted sample were then deposited on freshly cleaved mica (RubyRed Mica Sheets, Electron Microscopy Sciences, Fort Wash-ington, USA) and left to adsorb for 5 min. The sample was then rinsed with 400 µl of ultrapure water and dried with a gentle nitrogen flow. AFM imaging was performed on a Multimode 8 microscope equipped with a Nanoscope V controller and a type J piezoelectric scanner (Bruker, USA). Samples were scanned in air using Peak Force Tapping mode with Scanasyst-Air probes (Bruker, USA). We took special care to obtain images in which the met-alloid nanoparticles appeared well spread and isolated on the surface rather than overlapped and tangled. Raw images were first processed to remove background nonlinearity ( flattening) using Gwyddion v2.40 (http://gwyddion.net/). A threshold mask was then used to exclude the flat, empty areas of the images, singling out the aggregates for successive morphometric analysis. TeNPs lengths were evaluated by simply measuring the distance between the two furthest points in the original mask.