Synthesis and evaluation of novel enhanced gene reporter molecules: Detection of β-galactosidase activity using ¹⁹F NMR of trifluoromethylated aryl β-d-galactopyranosides

Gene therapy has emerged as a promising strategy for treatment of various diseases, but there is a pressing need for the development of non-invasive reporter techniques based on appropriate molecules and imaging modalities to assay gene expression. We now report the design, synthesis, and evaluation of novel enhanced reporter molecules, which reveal lacZ gene expression: trifluoromethylated aryl β-d-galactopyranosides. A series of five molecular structures were screened in solution and with stably transfected lacZ expressing human MCF7 breast cancer cells in vitro. p-Trifluoromethyl-o- nitrophenyl β-d-galactopyranoside (PCF₃ONPG) was found to exhibit valuable properties including a single ¹⁹F NMR signal, stability in aqueous solution and with wild type cells, but a chemical shift response to enzyme cleavage (Δδ = 1.14 ppm) in breast cancer cells transfected to stably express lacZ.