New Tb3+–simvastatin optical biosensor for sensitive determination of folic acid, progesterone, testosterone and vitamin D3 in biological fluids

Abstract

An innovative, simple and cost effective Tb³⁺–simvastatin photo probe was designed and used as a core for a spectrofluorometric approach to sensitively determine four vital biological compounds in different matrices. A Tb³⁺–simvastatin complex displays a characteristic electrical band with λ_em at 545 nm with significant luminescence intensity, which is quenched in the presence of folic acid, progesterone, testosterone and vitamin D₃ at four variant sets of pH: 5.0, 6.2, 7.5 and 9.0, respectively. The conditions were optimized and the best solvent for operation was found to be acetonitrile at λ_ex at 340 nm. Folic acid was successfully estimated in tablet dosage form, urine and serum in the concentration range of 2.49 × 10⁻⁹ to 1.28 × 10⁻⁶ mol L⁻¹. Progesterone, testosterone and vitamin D₃ were also assessed in serum samples using the same optimal conditions within concentration ranges of 5 × 10⁻⁹ to 1.9 × 10⁻⁶, 5 × 10⁻⁹ to 2.8 × 10⁻⁶ and 5 × 10⁻⁹ to 4.2 × 10⁻⁶ mol L⁻¹, respectively. The proposed luminescence method was validated in accordance with ICH guidelines and found to be accurate, precise, and specific and free from any interference at the working pH for each analyte. The cost effectiveness and applicability of the method make it a good choice for routine analysis of the four compounds and early diagnosis of chronic diseases associated with abnormalities in their physiological levels.