Printing functional protein microarrays using piezoelectric capillaries.

The use of piezoelectric dispensers for the fabrication of protein biochips has become a popular approach owing to its inherent advantages of noncontact with the printing surface and the opportunity for recovery of unused sample. Despite the inherent advantages of this printing method, little attention has been devoted to the quantitative aspects of dispensing small volumes of dilute protein solutions from the borosilicate glass capillaries employed by piezoelectric dispensers. Here, a method is detailed that demonstrates the benefits of using a low-ionic-strength phosphate printing buffer containing the carrier protein bovine serum albumin (BSA) to deposit capture antibody microspots. When this buffer is used to deposit biotinylated capture antibodies, 3.6- to 44-fold more protein is delivered to an avidin-coated surface compared to when the antibodies are deposited in standard phosphate-buffered saline (PBS) in the absence of BSA. Further, this method results in the deposition of capture antibodies that adopt a more uniform spot morphology.