Transition metal carbonyl clusters in biology: A futile or niche research area?

Transition metal carbonyl clusters (TMCCs) have seldom been considered in a biological perspective. Albeit generally flawed with low water-solubility and poor air-stability, drawbacks typical of all the organometallic complexes, selected TMCCs, designed by consolidated synthetic chemical routes, have so far encountered applications in few carefully selected biological fields, thus representing a very niche research area. This paper presents a brief overview of the applications of TMCCs in protein structural characterization, in hormone labelling, in carbonyl metallo-immunoassay (CMIA), as carbon monoxide releasing molecules (CORM) and, finally, as antiproliferative (antitumor) agents.