Probing the protein corona around colloidal metal nanoparticles in cellular environments using nanofocused X-ray synchrotron radiation

Metal NPs are organised in metal core, surface coating, and protein corona. Optical microscopy suggests that degradation of these elements in cells occurs at different rates, but fluorescence probes can detach or get degraded. X-ray fluorescence (XRF) using nanofocused X-ray is ideal to study the localisation of metal NPs with subcellular resolution. Recently, we developed a method to label surface coatings of NPs with brominated tags. This allowed performing XRF and XANES that confirmed differential cellular degradation of cores and coatings of Au NPs after long incubations. Yet, we do not know what happen at short incubations, or with the protein corona formed around those NPs. We want to use XRF maps in cells treated with colloidal NPs at ID16A to probe the relative localisation between Au cores, Br coatings and Gd-labelled proteins. This will provide new insight into the cellular degradation process of colloidal NPs, which is important to assess their potential as biomedical tools.