A method for inhibiting microbial growth comprises administering an effective amount of a silver complex of a N-heterocyclic amine. A method for treating cancer cells or a method for imaging one or more tissues of a patient includes administering an effective amount of a complex of a N-heterocyclic amine and a radioactive metal. N-heterocyclic carbenes of the present invention may be represented by formula (I) wherein Z is a heterocyclic group, and R<；SUB>；1 <；/SUB>；and R<；SUB>；2 <；/SUB>；are, independently or in combination, hydrogen or a C<；SUB>；1<；/SUB>；-C<；SUB>；12 <；/SUB>；organic group selected from the group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, arylalkyl, alkylaryl, heterocyclic, and alkoxy groups and substituted derivatives thereof.
