Ultrasensitive Fluorescent Biosensor for Creatinine Determination in Human Biofluids Based on Water Soluble Rhodamine B Dye-Au3+ ions Conjugate

Simple, ultrasensitive and selective diagnostic tool is required for the quantification of creatinine in human biofluids. To the best of our knowledge, we are reporting the second fluorescent as well as colorimetric biosensor for creatinine with a very good linear range. We have utilized a simple water soluble Rhodamine B dye as a probe because of its excellent emitting properties and quantum yield. As a colorimetric biosensor, the dye has selectively detected the Au3+ ions in a ratiometric aspect through ICT mechanism among all other interfering metal ions. When the creatinine was introduced, the Au3+ ions were gradually released from the dye and binded with the creatinine which finally enhanced the fluorescent intensity. The Stern Volmer quenching constant K-sv was found to be 2.6 x 10(9) M-1. As a colorimetric biosensor, the limit of detection and linear range for creatinine are found to be 54 nM and 100 nM to 15 mu M, respectively. Under the optimized condition, the fluorescent biosensor has detected the creatinine within the linear range of 10 nM to 1.2X10(-3)M along with the LOD of 5 nM. The linear range of developed biosensor implies that the biosensor can be applied for clinical diagnosis of muscle disorder (creatinine level < 40 mu M), extreme renal problem (creatinine level=1000 mu M). We have extended the application of this developed biosensor for the determination of creatinine in human urine sample and achieved a very good recovery.