Inert to bioactive - A multidimensional spectrum.

OBJECTIVE

To clarify the terminology and its application in the context of materials placed in contact with tissues in living systems.

METHODS

Review the nature of both the biological and chemical reactions occurring in such contexts with a view to a classification of types of behaviour and thus types of material.

RESULTS

A range of types of behaviour was identified with clear diagnostic characteristics. Materials could thus be classified accordingly, with the possibility of more than one type of behaviour being exhibited. 'Bioactivity' was concluded to depend solely on the modulation of a natural biological process, but excluding pharmaceutical action.

SIGNIFICANCE

Clarity in the characterisation and labelling of materials and their behaviours in biological systems will benefit the interpretation of the literature, the design of experiments, and future research directions.