In vivo CRISPR biosensing

In vivo biosensing is essential for real-time monitoring of biological processes and disease progression within living organisms. Leveraging the programmable specificity and multifunctionality of CRISPR effectors, in vivo CRISPR-based biosensing has emerged as a powerful tool for highly sensitive and target-specific detection in complex physiological environments. This review presents the fundamental principles, design strategies, and bioanalytical applications of these advanced sensors, focusing on three key approaches: CRISPR-mediated highly efficient in vivo sequence recognition, CRISPR-driven trans-cleavage activity for signal amplification, and the use of base editors and prime editors for sensing-coupled genetic modulation. Critical design parameters-including delivery strategies, intracellular dynamics, and signal amplification mechanisms-are discussed in detail. We further highlight a broad range of applications, including in vivo DNA/RNA imaging, quantification of proteins and small molecules, gene-controlled drug release, dynamic signal recording, environmental response sensing, and lineage tracing in embryogenesis and tumor progression. The current challenges and outlining future directions are also discussed, underscoring the transformative potential of in vivo CRISPR biosensing in both fundamental biology and clinical translation.