A carbon dots based fluorescent probe for selective and sensitive detection of hemoglobin

In this work, we presented a rapid, selective and highly sensitive probe for hemoglobin (HGB) based on the quenched fluorescence of carbon dots (CDs). The CDs were synthesized by microwave irradiation technique in one pot according to our previous report. The fluorescence of CDs was effectively quenched by HGB due to the ground state complex formation between CDs and HGB. A number of key factors including the amount of CDs, pH value of phosphate buffer solution, the concentration of salt solution, and the reaction time those influenced the analytical performance of CDs in HGB determination were investigated thoroughly. Under the experimental conditions, the fluorescence intensity of CDs was inversely proportional to the concentration of HGB ranging from 1 to 4000 nM with a correlation coefficient of 0.9987. The limit of detection for HGB was as low as 0.12 nM. Some common substances, including other heme proteins, did not affect HGB determination significantly. The method was utilized to detect HGB in human urine and human blood samples with satisfactory results. The static quenching mechanism of this system was further investigated by UV-vis absorption spectrometry and time-resolved fluorescence spectrometry. The a-helix content of HGB decreased and the secondary structure of HGB was rearranged after the interaction with CDs. (C) 2015 Elsevier B.V. All rights reserved.