Correlating surface plasmon resonance microscopy of living and fixated cells with electron microscopy allows for investigation of potential preparation artifacts

The investigation of the cell-substrate interface is of great importance for a broad spectrum of areas such as biomedical engineering, brain-chip interfacing and fundamental research. Due to its unique resolution and the prevalence of instruments, electron microscopy (EM) is used as one of the standard techniques for the analysis of the cell-substrate interface. However, possible artifacts that might be introduced by the required sample preparation have been the subject of speculation for decades. Due to recent advances in Surface plasmon resonance microscopy (SPRM), the technique now offers a label-free alternative for the interface characterization with nanometer resolution in axial direction. In contrast to EM, SPRM studies do not require fixation and can therefore be performed on living cells. Here, we present a workflow that allows us to quantify the impact of chemical fixation on the cell-substrate interface. These measurements confirmed that chemical fixation preserved the average cell-substrate distances in the majority of studied cells. Furthermore, we were able to correlate the SPRM measurements with EM images of the cell-substrate interface of the exact same cells allowing us to identify regions with good agreement between the two methods and reveal artifacts introduced during further sample preparation.