TY - JOUR
T1 - Kinetics of insulin adsorption at the oil-water interface and diffusion properties of adsorbed layers monitored using fluorescence correlation spectroscopy
AU - Donsmark, Jesper
AU - Jorgensen, Lene
AU - Mollmann, Susanne
AU - Frokjaer, Sven
AU - Rischel, Christian
PY - 2006/1/1
Y1 - 2006/1/1
N2 - The adsorption of insulin at an oil-water interface was studied with fluorescence correlation spectroscopy (FCS). FCS is able to measure diffusion properties of insulin at nanomolar concentrations, making it possible to detect the very early steps in the adsorption process. Below 20 nM bulk insulin concentration, the insulin molecules adsorbed to the surface diffuse freely at all times during the experiment (a few hours). At higher concentrations, a surprisingly abrupt transition to a slow diffusion phase is observed. Based on the information about both diffusion times and molecular brightness derived from the FCS experiments, we suggest that the transition represents the formation of a fractal network. FCS may be a valuable tool in pharmaceutical formulation science, because it provides information about concentration buildup and phase changes at interfaces formed in drug delivery systems.
AB - The adsorption of insulin at an oil-water interface was studied with fluorescence correlation spectroscopy (FCS). FCS is able to measure diffusion properties of insulin at nanomolar concentrations, making it possible to detect the very early steps in the adsorption process. Below 20 nM bulk insulin concentration, the insulin molecules adsorbed to the surface diffuse freely at all times during the experiment (a few hours). At higher concentrations, a surprisingly abrupt transition to a slow diffusion phase is observed. Based on the information about both diffusion times and molecular brightness derived from the FCS experiments, we suggest that the transition represents the formation of a fractal network. FCS may be a valuable tool in pharmaceutical formulation science, because it provides information about concentration buildup and phase changes at interfaces formed in drug delivery systems.
KW - Adsorption
KW - Fluorescence
KW - Fluorescence correlation spectroscopy
KW - Insulin
KW - Oil-water interface
UR - http://www.scopus.com/inward/record.url?scp=32244435209&partnerID=8YFLogxK
U2 - 10.1007/s11095-005-8636-3
DO - 10.1007/s11095-005-8636-3
M3 - Journal article
C2 - 16307385
AN - SCOPUS:32244435209
SN - 0724-8741
VL - 23
SP - 148
EP - 155
JO - Pharmaceutical Research
JF - Pharmaceutical Research
IS - 1
ER -