biostudies-literatureUnknownHanff VIn this work, we present several visible-light cleavable crRNAs targeting two different genes for regulating Cas9 activity. The crRNAs contain a total of three different photocleavable linker (PL) which induce a bond break when irradiated with a suitable wavelength. Cleavage of the crRNAs efficiently inhibits Cas9 activity, as demonstrated by the <i>in vitro</i> Cas9 assay developed in this work. By using visible light, our approach will enable precise downregulation of Cas9 activity in terms of location and timing, thereby enabling non-invasive and harm free control over genome editing for safer application.RSC chemical biologyhttps://www.ebi.ac.uk/biostudies/studies/S-EPMC12908655biostudies-literatureOptical control of Cas9 activity through visible-light cleavable crRNAs.PMC12908655Heckel AKaufmann JKlimek RKim JLanger KAJerabek SHanff VEgli DfalseOptical control of Cas9 activity through visible-light cleavable crRNAs.In this work, we present several visible-light cleavable crRNAs targeting two different genes for regulating Cas9 activity. The crRNAs contain a total of three different photocleavable linker (PL) which induce a bond break when irradiated with a suitable wavelength. Cleavage of the crRNAs efficiently inhibits Cas9 activity, as demonstrated by the <i>in vitro</i> Cas9 assay developed in this work. By using visible light, our approach will enable precise downregulation of Cas9 activity in terms of location and timing, thereby enabling non-invasive and harm free control over genome editing for safer application.2026-01-01T00:00:00Z2026 Jan2026-07-16T05:12:48.089Z2026-07-09T10:37:34.625ZS-EPMC129086554170432110.1039/d5cb00294j