EGFP IVT saRNA (m5C modified) is a self-amplifying RNA (saRNA) designed for robust and prolonged expression of enhanced green fluorescent protein (eGFP). This saRNA contains a Cap1 structure, validated 5' and 3' UTRs, and features a 110 nt polyA tail, all of which contribute to its high translation efficiency and stability. The Cap1 structure helps evade the innate immune response and enhances translation, while the optimized UTRs and polyA tail further improve mRNA stability and expression. Additionally, the incorporation of 5-methylcytidine (m5C) reduces immunogenicity and enhances expression levels. This formulation allows for sustained eGFP expression, observable up to 21 days post-transfection. This formulation is suitable for applications in gene expression studies, vaccine development, and delivery system optimization.