This solution exchange is optimal for patch clamp, single-cell microamperometry, and microfluorometry experiments.
The presented microfluidic method would be applicable to biochemical lab-on-a-chips with integrated fluid replacement steps, such as affinity elution and solution exchange during biosensor signaling.
Membrane vesicles, proteoliposomes or membrane fragments containing the transporter are adsorbed to the solid supported membrane and are activated by providing a substrate or a ligand via a rapid solution exchange.
Subsequent experiments were carried out to investigate the effect of solution exchange at low pH (i.e. the decrease of dissolved aluminum) to check to what extent the effects initially observed could be reversed.
Open squares: in absence of added aluminum, full squares: after addition of aluminum (concentration of 3 μM), diamonds and triangles: after replacing the 500 ml solution from the previous experiment by 1 mM NaCl, and subsequent solution exchange.
The solution exchange was done by gravity flow.
The bath solution was completely replaced within 1.5 seconds, allowing a solution exchange time of about 25 ms around the oocyte.
A fast perfusion system was used to exchange extracellular solutions, with complete solution exchange achieved in ∼1 to 3 s [30].
The rate of solution exchange was studied using solutions with different KCl concentrations and found to be about 95% complete within 20 s.
In the case of Cl− concentration jumps, NA contained aspartate− at the same concentration as Cl− to minimize solution exchange artifacts.
Concentration jumps of Br− and I− generate large solution exchange artifacts due to the strong interaction of the anions with the lipid headgroups on the SSM [35].
