Protein microdeposition using a conventional ink-jet printer

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.