Figure 1 (IMAGE) Kanazawa University Caption (a) Explanatory sketch of the plasma membrane anchored nanosensor. The compounds used for gold nanoparticles (AuNP) conjugation are the H<sub>2</sub>O<sub>2</sub>-sensitive 4-mercaptophenylboronic pinacol ester (4MPBE) and Biotin-HPDP. Biotinylation of the plasma membrane protein ectodomains is obtained using NHS-Biotin. The anchoring of the conjugated AuNP and NHS-Biotin is given by Streptavidin reacting with the two biotin moieties. (b) AFM analysis was performed on A549 lung cancer cells after nanosensor anchoring and fixation. High resolution AFM images confirmed the presence of the nanosensor, which is in contact with the cell surface and is capable of detecting endogenous H<sub>2</sub>O<sub>2</sub> in a very shallow region (i.e., 90 nm) of the extracellular fluid in contact with the plasma membrane. Credit Kanazawa University Usage Restrictions The image may only be used with appropriate caption and credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.