Novel Technology (Amplification based)

Rolling circle amplification

Rolling circle amplification technology is a highly sensitive amplification method for the detection of target molecules in a wide array of testing formats. The technology allows recognition, amplification and detection of targets directly on a solid support, such as within a cell (in situ) or on a microarray/biochip.

Unlike the polymerase chain reaction, RCA is a relatively novel technology that can be utilised for both signal and target amplification (Lizardi et al., 1998). Linear and exponential forms of the technique have been developed.

Linear RCA involves the amplification of circular DNA by polymerase extension of a complementary primer. This process generates concatermerized copies of the circular DNA template. Therefore target amplification is limited to circular nucleic acids such as circular viruses and plasmids.
(Click  for a diagram of the process)

Exponential RCA is similar to the linear process except that it uses a second primer of identical sequence to the DNA circle (*Lizardi et al., 1998). This two-primer system achieves isothermal, exponential amplification. Exponential RCA has been applied to the amplification of non-circular DNA through the use of a linear probe that binds at both of its ends to contiguous regions of a target DNA followed by circularisation using DNA ligase.

In addition, RCA can be employed as a signal amplification technique, thereby allowing multiplexing and direct amplification on a solid phase such as in the case of microarrays.