siRNA-targeted modification is a gene silencing method based on RNA interference technology, the basic principle of which is to utilize siRNA molecules with specific sequences to target specific genes, thereby inhibiting the expression of the genes. This technology provides a powerful tool for the treatment of diseases, especially in the treatment of cancer and hereditary diseases, and shows a broad application prospect.

The process of siRNA targeting involves three main steps: synthesis, maturation and targeting. First, the precursor mRNA of siRNA is cleaved into a double-stranded RNA of about 21-23 bases by the enzyme Dicer, and then the double-stranded RNA binds to the RNA-induced gene silencing complex (RISC) to form a functionally mature siRNA, which binds to the complementary sequences of the mRNA to mediate the degradation of the mRNA or translational repression to achieve the effect of gene silencing. The effect of gene silencing is realized.

In terms of choosing a suitable target, scientists usually select the coding region in the mRNA sequence of the target gene and try to avoid sequence similarity with other genes to minimize non-specific targeting effects. In order to increase the targeting effect, targeting at 1/3 of the region of the target gene is usually chosen. When designing siRNA sequences, RNA molecules 21-23 nucleotides long are usually chosen, mainly consisting of antisense and synonymous strands. In order to increase the targeting effect, a LuHu nucleotide can be added in the middle of the antisense and synonymous strands to prevent the formation of a stable secondary structure between the antisense and synonymous strands.

In conclusion, siRNA targeted modification is a gene silencing method based on RNA interference technology, which provides a powerful tool for disease treatment.