TY - JOUR
T1 - Combined scanning electrochemical microscopy-Langmuir trough technique for investigating phase transfer kinetics across liquid/liquid interfaces modified by a molecular monolayer
AU - Zhang, Jie
AU - Strutwolf, Jörg
AU - Cannan, Susan
AU - Unwin, Patrick R.
PY - 2003/2/1
Y1 - 2003/2/1
N2 - The first combination of scanning electrochemical microscopy (SECM) with a Langmuir trough for liquid/liquid interfaces is described. The technique has been examined and demonstrated through investigations of the effect of monolayers of L-α-phosphatidylcholine, distearoyl (DSPC) on the kinetics of oxygen transfer from decane to water. The stability of monolayers, formed in this way, on the timescale of SECM measurements has been identified as a function of compression speed and subphase composition. Monolayers were stable over a wide range of pressures and molecular areas, but at high compression a decrease in surface pressure with time was observed. This effect was attributed to desorption of the lipid from the interface. In this situation, it was possible to perform SECM measurements (tip-interface approach curves) rapidly under surface pressure control, without causing significant disturbance to the monolayer. DSPC had no detectable effect on the oxygen transfer kinetics when the monolayer was in the liquid-expanded phase, but in the liquid-condensed phase a significant decrease in the rate of oxygen transfer was observed.
AB - The first combination of scanning electrochemical microscopy (SECM) with a Langmuir trough for liquid/liquid interfaces is described. The technique has been examined and demonstrated through investigations of the effect of monolayers of L-α-phosphatidylcholine, distearoyl (DSPC) on the kinetics of oxygen transfer from decane to water. The stability of monolayers, formed in this way, on the timescale of SECM measurements has been identified as a function of compression speed and subphase composition. Monolayers were stable over a wide range of pressures and molecular areas, but at high compression a decrease in surface pressure with time was observed. This effect was attributed to desorption of the lipid from the interface. In this situation, it was possible to perform SECM measurements (tip-interface approach curves) rapidly under surface pressure control, without causing significant disturbance to the monolayer. DSPC had no detectable effect on the oxygen transfer kinetics when the monolayer was in the liquid-expanded phase, but in the liquid-condensed phase a significant decrease in the rate of oxygen transfer was observed.
KW - Langmuir monolayer
KW - Phospholipid
KW - SECM
KW - Ultramicroelectrodes
UR - http://www.scopus.com/inward/record.url?scp=0037295071&partnerID=8YFLogxK
U2 - 10.1016/S1388-2481(02)00544-1
DO - 10.1016/S1388-2481(02)00544-1
M3 - Article
AN - SCOPUS:0037295071
SN - 1388-2481
VL - 5
SP - 105
EP - 110
JO - Electrochemistry Communications
JF - Electrochemistry Communications
IS - 2
ER -