We present the data on tests of biologically active composites, which simulate the properties of human skin and allow us to investigate the violations of exchange of lipid substances. The models are constructed by immobilization of some lipids on the matrix of polymeric porous films and in the pores in statics and dynamics. It is shown that a process of formation of bioactive composite, which corresponds to morphofunctional characteristics of skin, depends on the type of matrix structure, the dimensions of pores, and the regime of inputting of lipid-content solutions that provide formation of infinite cluster in pore space. Using the models obtained, we study the factors, which influence the accuracy of the method of detection of cholesterol content on plane surfaces. The latter is important for selection of optimal conditions for diagnostics of some diseases based on the analysis of cholesterol content in skin.