Rolling Circle Amplification Boosts Ultrasensitive Liquid Biopsy

Liquid biopsy is a minimally invasive and convenient diagnostic and monitoring method for diseases, involving the collection and analysis of samples such as blood, urine, and cerebrospinal fluid. However, due to the intricate matrix composition of biological samples, there remains a need for further enhancement of sensitivity and specificity in current liquid biopsy methods to adequately meet clinical requirements. Rolling circle amplification (RCA) is an efficient isothermal enzymatic reaction capable of rapidly producing numerous ultra-long single-stranded DNA molecules with repetitive sequences. By custom-designing the DNA template sequence, RCA can generate functional products that integrate with various functional groups, achieving signal amplification and output with exceptional specificity and sensitivity in liquid biopsy. In this review, the fundamental principles and classifications of RCA are first introduced. Then, the coupling strategies of RCA with various detection technologies are systematically summarized, along with their prospects and challenges of clinical applications that have not been addressed in previous reviews, and the recent developments of RCA-based biosensors in liquid biopsy are explored. Finally, the challenges associated with the integration of RCA in liquid biopsy are discussed and potential directions for future advancements are proposed.