The CRISPR (clustered regularly interspaced short palindromic repeats) system has emerged as a revolutionary gene-editing tool with immense potential in gene therapy, functional genomics, and beyond. However, achieving precise spatiotemporal control of gene editing in specific cells and tissues while effectively mitigating potential risks, such as off-target effects, remains a key challenge for its clinical translation. To overcome these limitations, researchers have developed innovative strategies based on chemical modifications of oligonucleotides to enhance the precision, efficiency, and controllability of CRISPR/Cas9-mediated gene editing. By introducing conditional responsive elements, such as photosensitive groups, small-molecule responsive units, and supramolecular structures, they have successfully achieved precise spatiotemporal and dose-dependent regulation of CRISPR/Cas9 function. This review provides a comprehensive overview of recent advancements in gRNA regulation strategies based on chemical modifications of oligonucleotides, discussing their applications in improving the efficiency, specificity, and controllability of CRISPR/Cas9 editing. We also highlight the challenges associated with the conditional control of gRNA and offer insights into future directions for the chemical regulation of gRNA to further advance CRISPR/Cas9 technology.

Hammerhead ribozymes are a class of small RNA molecules with catalytic activity. Their compact size, high catalytic efficiency, structural simplicity, and modular design flexibility make them ideal tools for RNA manipulation and gene regulation. In recent years, these ribozymes have demonstrated tremendous application potential across diverse fields, including gene regulation, disease therapy, and biosensing, significantly advancing related research. This article provides a comprehensive review of recent progress in hammerhead ribozyme research within synthetic biology, thoroughly examines the current challenges, and outlines future development directions, aiming to offer valuable perspectives and insights for their biomedical applications.