Biological solution interface, examination

A compromise solution for dereplication procedures is to use a combination of ionization modes. In one report (31), electrospray MS in both positive and negative modes was coupled to an HPLC interface and used to obtain information on unknown components of crude biologically active extracts. The authors of this report claimed successful identification of a known natural product in two out of eight biologically active extracts examined, another two compounds were identified as novel, and they assumed that the active components in the remaining four did not ionize or were present at a concentration below the limits of MS detection. 

This indeed is not an easy task to examine because it may well be that it is only at certain sites in a membrane that there is sufficient electronic conductivity for the electrode to function. It may well be that our model of a biological electrode (say a membrane) is a model of an insulating layer in which are insulated a number of wires, and this would mean that the proteins which are part of biomembranes, and which stick through them, may be the source of the transport between the two sides of the membrane and an origin of an electron and proton transfer site at the protein-solution interface (Figure 19). 

Experiments with membranes containing immobilized proteins are more difficult than those in which the proteins are free and dissolved in the solution, later adsorbing temporarily to collect or give electrons to the promoter-modified electrode. In biological cells of living systems, the membranes, some with enzyme layers attached, are extremely thin. It would be difficult to find an experimental arrangement in which such a layer of actual biomaterial could be made into an electrode attached to an outer power source, etc. Because of such difficulties, the examination of electron transfer at the interfaces of biosystems has been a path less traveled. 

Chapter 1 presents an overview of fluorinated surfactants. The synthesis of fluorinated surfactants is discussed in Chapter 2. Since the space limitations precluded a detailed description of processes, patent citations are augmented by references to Chemical Abstracts. Physical and chemical properties are reviewed in Chapter 3. Chapters 4-7 are devoted to the theory of fluorinated surfactants liquid-vapor and liquid-liquid interface (Chapter 4), solid-liquid interface (Chapter 5), solutions of fluorinated surfactants (Chapter 6), and the structure of micelles and mesophases, including mixed surfactant systems, in Chapter 7. The practical application of fluorinated surfactants is the subject of Chapter 8. Various applications are listed in alphabetical order for easy access to information. Chapter 9 reviews the analytical and physical methods for the investigation of fluorinated surfactants. Chapter 10 examines the environmental and toxicological aspects, including the use of fluorinated surfactants in biological systems. 

---