Gibco dulbecco s phosphate buffered saline

For detection of cell surface–expressed proteins, isolation via Pierce Cell Surface Protein Isolation Kit (Thermo Fisher Scientific) was performed according to the manufacturer’s instructions with two additional washing steps using Gibco Dulbecco's Phosphate Buffered Saline (Thermo Fisher Scientific) after quenching the biotinylation reaction. Analysis of the cell surface fraction was performed via immunoblot.

Platinum microelectrodes were fabricated by sealing a 50 µm diameter platinum wire (99.99% purity; hard, Goodfellow, UK) inside a quartz glass capillary (L, 150 mm; o.d., 1.0 mm; i.d., 0.3 mm, Sutter Instruments, USA). The capillary was then pulled using a P-2000 Micropipette Puller (Sutter Instrument Company, USA). An Ag/AgCl (saturated KCl) electrode was used as reference. The microelectrodes were electrochemically characterized by recording cyclic voltammograms and approach curves over a silicon wafer in a 5 mmol L⁻¹ [Ru(NH₃)₆]Cl₃ + 0.1 mol L⁻¹ KCl solution. The electrochemically-active radius and the RG values (RG = rg/ r, where rg is the radius of the overall tip, including the active platinum disc and the surrounding insulator; r is the radius of the platinum microdisc) of two different microelectrodes were determined by fitting approach curves^{43 (link)} before the platinization of the surface. Values were found to be 5 µm (RG = 8) and 500 nm (RG = 15). The smaller microelectrode was used in the SECM image experiment. The calibration plot for oxygen was prepared by using steady-state current values obtained from cyclic voltammograms recorded in a Gibco Dulbecco’s phosphate buffered saline (Thermo Fisher Scientific, USA) solution containing oxygen at different concentrations.