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Immobilizing a protein, that is fully compatible with the patient, on the surface of a biomedical device should make it possible to avoid adverse responses such as inflammation, rejection, or excessive fibrosis. A surface that strongly binds and does not denature the compatible protein is required. Hydrophilic surfaces do not induce denaturation of immobilized protein but exhibit a low binding affinity for protein. Here, we describe an energetic ion-assisted plasma process that can make any surface hydrophilic and at the same time enable it to covalently immobilize functional biological molecules. We show that the modification creates free radicals that migrate to the surface from a reservoir beneath. When they reach the surface, the radicals form covalent bonds with biomolecules. The kinetics and number densities of protein molecules in solution and free radicals in the reservoir control the time required to form a full protein monolayer that is covalently bound. The shelf life of the covalent binding capability is governed by the initial density of free radicals and the depth of the reservoir. We show that the high reactivity of the radicals renders the binding universal across all biological macromolecules. Because the free radical reservoir can be created on any solid material, this approach can be used in medical applications ranging from cardiovascular stents to heart-lung machines.

An electrochemical metal ion sensor has been developed with a detection limit of less than 0.2 ppt by the covalent attachment of the tripeptide Gly-Gly-His as a recognition element to a 3-mercaptopropionic acid modified gold electrode.

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A total of 29 transition metals (all except Tc), all as ions M(+), have been reacted with gaseous S(8). The reactivities and reaction products provide a unique set of comparative data on a fundamental reaction of the elements. The results underlie the interpretation of many other processes and compounds in condensed phases. Series of product ions [MS(y)()](+) are formed, with y generally starting at 4, and increasing with time through 8 up to 10, 12, 16, or 21 (for La(+)). A general mechanism is proposed, in which the first {MS(8)}(+) encounter complex is reactive and undergoes S-S bond scission and rearrangement around the metal, such that [MS(8)](+) is not an early product. The early transition metals react faster than later members of the series, and third row metals react about twice as fast as first row metals. The metals which are more chalcophilic in condensed-phase chemistry are apparently less so as M(+); Hg(+) does not form observable [HgS(y)()](+) (except for a very low yield of [HgS(3)](+)) and is remarkably less reactive with sulfur than most of the other metal ions. Simple electron transfer between M(+) and S(8) does not occur except possibly for Ir(+), but S(8)(+) is sometimes observed and is believed to be formed by electron transfer from S(8) to some [MS(y)()](+) complexes. Interpretation of the rates of reaction of the ions of groups 3, 4, and 5 with S(8) is complicated because they react with adventitious water in the cell forming oxo-species. The results are discussed in the context of condensed-phase metal polysulfide chemistry.