Improved method for the preparation of nonyl acridine orange analogues and utilization in detection of cardiolipin†
This study was designed to develop a fast and convenient methodology for the preparation of 10-nonyl acridine orange (NAO) and its silyl analogues to improve their photo-physical properties for the detection and quantification of cardiolipin (CL). Optimized conditions allow the effective synthesis of NAO analogues with good yield and excellent purity. The introduction of a 3-(trimethylsilyl)propyl moiety improves the dye's solubility and stability in buffer solution and increases its emission intensity by ≈30%. The novel dye can be used for the selective quantification of CL in a liposomal inner mitochondrial membrane model with greater fluorescence intensity and linear slope compared to NAO. The novel silicon-containing NAO analogue has lower cytotoxicity, and is a convenient fluorescent dye for cell staining.