Many recent bioanalytical systems based on immunologic and hybridization re
actions in a mono- or bidimensional microarray format require technology th
at can produce arrays of spots containing biospecific molecules. Some micro
array deposition instruments are commercially available, and other devices
have been described in recent papers. We describe a system obtained by adap
ting a commercial ink-jet printer and used to produce mono- and bidimension
al arrays of spots containing horseradish peroxidase on cellulose paper. In
a few minutes, it was possible to obtain bidimensional arrays containing s
everal thousands of spots with a diameter as low as 0.2 mm, with each of wh
ich requiring only a few nanoliters of the enzyme deposition solution. The
quantity of enzyme in each spot was evaluated with a chemiluminescent react
ion and a charge-coupled device-based, low-light imaging luminograph. The c
hemiluminescence measurements revealed that the reproducibility of the enzy
me deposition uas satisfactory for analytical purposes, with the variation
coefficients being lower than 10% in almost all cases.