Construction and validation of a rapid semen identification system based on SHERLOCK technology

This study developed a rapid detection system for semen-specific mRNA based on CRISPR/Cas13a system to meet the timeliness requirements of forensic on-site body fluid identification. Specific primers and CRISPR RNA (crRNA) short fragments on semen specific mRNA genes were designed and screened, to establish a SHERLOCK detection method based on technology principles of CRISPR/Cas. Furthermore, nucleic acid rapid release agents for treating samples were screend to construct a new detection method in combination with SHERLOCK, and the specificity and sensitivity of the method were tested. The method can rapidly detect the presence of semen from unknown body fluid samples, and the relative fluorescence unit (RFU) value of the semen sample is significantly higher than those of non-semen samples (P < 0.0001), with a sample detection sensitivity of down to 0.25 μL. The construction of the rapid semen detection method using rapid extraction and SHERLOCK reduces operation time, significantly reduces instrument dependence, and provides an innovative solution for forensic on-site rapid body fluid identification.