Amplification-free CRISPR/Cas biosensors for point-of-care nucleic acid detection: recent advances and future perspectives

Nucleic acid biomarkers are critical targets for early diagnosis of disease, public health surveillance and environmental safety. However, their low abundance and the complexity of the sample matrix pose strict requirements for the high sensitivity and portability of detection technologies. Although traditional clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems exhibit advantages such as high specificity, operational simplicity, and compatibility with mild reaction conditions, their reliance on pre-amplification steps elevates the risk of false-positive results and hinders their broader application. To overcome these limitations, amplification-free CRISPR/Cas technologies have emerged and undergone extensive development. These approaches enable highly sensitive nucleic acid detection without the need for pre-amplification and are more amenable to integration with portable devices, thereby offering promising avenues for point-of-care testing (POCT). This review systematically examines the fundamental principles and design strategies underlying amplification-free CRISPR/Cas biosensors and summarizes recent advances in detection platforms based on autocatalytic signal enhancement, nanomaterial-coupled amplification, and integrated high-sensitivity readout systems, while also outlining their practical applications in POCT settings. Furthermore, the key technical challenges and future development directions of amplification-free CRISPR technologies are discussed based on current advances in the field. These insights and perspectives aim to provide a systematic reference for further research and to facilitate the expanded application of amplification-free CRISPR/Cas systems in POCT.