Ry. Lin et al., ENTROPY-DRIVEN BINDING PARTITION OF AMINO-ACIDS DIPEPTIDES TO STRATUM-CORNEUM LIPID VESICLES/, Journal of controlled release, 50(1-3), 1998, pp. 51-59
This study employed large unilamillar vesicles composed of purchased s
tratum corneum lipids to investigate the binding/partition of amino ac
ids/dipeptides to stratum corneum lipid vesicles. The partition coeffi
cients of amino acids/dipeptides between the stratum corneum lipid ves
icles and the acetate buffer were determined by HPLC. In addition, the
binding/partition enthalpy of amino acids/dipeptides with the stratum
corneum lipid vesicles was derived by directly measuring the binding/
partition heat with isothermal titration calorimetry. According to the
binding/partition Gibbs free energy and the binding/partition enthalp
y, all the binding/partition of amino acids/dipeptides with the stratu
m corneum lipid vesicles is endothermic, implying an entropy-driven bi
nding/partition. Also, the equilibrium binding/partition results demon
strate that the partition coefficients of amino acids/dipeptides do no
t correlate with the transdermal permeability. This finding suggests t
hat either the interaction between the penetrants and the lipid bilaye
r between corneocytes may not be a determining step or that the parace
llular path is not a dominant route of transdermal penetration. (C) 19
98 Elsevier Science B.V.