determination of prostate cancer biomarker, citrate ion, by electrochemiluminescence sensor based on nanopim/n-cqds luminophore

Types of cancer, diagnosis of this disease in early stages is crucial for treatment. studies showed that citrate ion level in men body fluids, especially in urine, could be one of the important signs of this cancer in early stages [1]. citrate has special functions in prostate gland and during the cancer disease its secretion is reduced to lower levels than normal (0.06-0.14 mm) [2]. therefore, determination of citrate as an important biomarker of prostate cancer could help to diagnosis the cancer in early stages. although different methods have been used to determination of citrate, electrochemiluminescence (ecl) has not been studied yet [1, 3]. ecl has become one of the important analytical methods for determination of various analytes because of its high sensitivity and selectivity. classical ecl luminophores like tris(bipyridine)ruthenium(ii), are toxic and expensive. therefore, it is essential to find the new luminophores for preparation of green and cheap ecl sensors. in this study, an ecl sensor for determination of citrate ion was prepared using nanostructure polymer of intrinsic microporosity (nanopim) as ecl enhancer of n-cqds/s2o8-2 system. based on the results of our previous study, ecl of n-cqds was quenched by the citrate ion [4] and this quenching later was observed to be more sensitive and linear using nanopim/n-cqds as luminophore. therefore, it was proposed to develop the mentioned ecl sensor for determination of citrate in human serum and urine. nanopim was synthesized form the bulk pim and characterized by ft-ir, fesem, dls, zeta potential and pl methods. the linear range and lod of determination were 5×10-4 to 10-7 m and 2.23×10-8 m respectively. prepared sensor also was successfully applied for determination of citrate in human serum and patient urine with the recoveries of 97.7% and 86.0% respectively. considering the broad linear range, high sensitivity and selectivity of the sensor in real samples, comparing with previously used methods for determination of citrate, it showed that prepared sensor could be applied for screening of citrate in human biological fluids for diagnosing of prostate cancer in early stages.