From Gold to Polymer: Latex Bead-Assisted CRISPR-Cas12a Platform for Next-Generation Protein Diagnostics

Sensitive and accurate detection of protein biomarkers in clinical samples is crucial for early disease diagnosis and monitoring treatment outcomes. Although gold nanoparticle (AuNP)-assisted CRISPR-Cas12a biosensors have shown promise, their practical applications have been restricted by limitations of AuNPs, such as costly and complex synthesis, tendency to aggregate, and nonspecific adsorption of various unwanted species. To address these limitations, herein, we report a CRISPR-Cas12a-based fluorescence biosensor for the detection of a well-established and clinically significant inflammatory biomarker, interleukin-6 (IL-6), which employs latex beads instead of AuNPs as a transducer and signal amplifier. By the combined use of IL-6 detection antibody-functionalized magnetic beads, dual-functionalized latex beads, which carry both IL-6 detection antibodies and multiple dsDNA strands per antibody molecule, and the Cas12a-crRNA system, our method was able to detect IL-6 with a limit of detection (LOD) reaching as low as 0.76 pg/mL. Moreover, our sensor was highly selective: nontarget proteins such as human serum albumin (HSA), bovine serum albumin (BSA), C-reactive protein (CRP), procalcitonin (PCT), and IL-2β would not interfere with the detection of IL-6. In addition, the practical application of this sensor was assessed by successfully analyzing simulated serum samples. This study shows that latex beads can serve as an alternative to gold nanoparticles for CRISPR-based protein diagnostics. This approach improves stability and specificity while maintaining a high level of sensitivity for early disease diagnosis.