Direct lysis combined with amplification-free CRISPR/Cas12a-SERS genosensor for ultrafast and on-site identification of meat authenticity

A novel direct lysis method combined with amplification-free CRISPR/Cas12a-SERS genosensor was for the first time developed to rapidly and sensitively identify meat adulteration. Notably, polystyrene (PS) microspheres, with distinct shrinking and swelling properties, were dexterously employed to encapsulate biological-silent Raman reporter 4-mercaptobenzonitrile (4-MBN) and act as a controlled-release signal probe. Target DNA activated the trans-cleavage activity of CRISPR/Cas12a towards ssDNA linked with PS microsphere to liberate the signal probe, which was able to release numerous Raman reporters after treatment with THF solution, resulting in high signal amplification. Through this platform, trace target DNA was deftly transformed into a sensitive Raman signal and could be on-site determined through a portable Raman equipment. Under optimized conditions, this strategy displayed good linearity in the range 1-450 ng/mu L (R2 = 0.9943) and favorable sensitivity with limit of detection as low as 0.23 ng/mu L without any pre-amplification. Moreover, it exhibited good applicability to on-site identification of commercial meat samples in complicated food matrix. In addition, DNA extraction by direct lysis and amplification-free detection realized ultrafast meat adulteration determination within 35 min from sampling to result. This method possessed great potential in rapid and on-site accurate determination of meat authenticity.