Open circle probes with intramolecular stem structures

Disclosed are compositions and methods for reducing or eliminating generation of unwanted, undesirable, or non-specific amplification products in nucleic acid amplification reactions, such as rolling circle amplification. One form of composition is an open circle probe that can form an intramolecular stem structure, such as a hairpin structure, at one or both ends. The stem structure allows the open circle probe to be circularized when hybridized to a legitimate target sequence but results in inactivation of uncircularized open circle probes. This inactivation, which preferably involves stabilization of the stem structure, extension of the end of the open circle probe, or both, reduces or eliminates the ability of the open circle probe to prime nucleic acid synthesis or to serve as a template for rolling circle amplification. The disclosed method is useful for detection, quantitation, and/or location of any desired analyte, such as proteins and peptides.