Enhanced fluorescence of chitosan based on size change of micelles and application to directly selective detecting Fe3+ in humanserum

In this paper, we have developed an approach to significantly enhance fluorescence of chitosan by simply heated the inherently low fluorescent chitosan aqueous solution. Enhanced blue fluorescence of chitosan solution was observed as originated from the formation of small size of chitosan micelle after long time heated. The fluorescence of chitosan micelles was quenched and recovered when Fe3+ ions were combined and released from chitosan micelles. Therefore, chitosan without modification of functional groups can recognize Fe3+ with very high selectivity. As a result, a new fluorescence sensor for sensitively detecting Fe3+ ion based on the change of chitosan micelles sizes was subsequently fabricated. This enhanced fluorescence enables the chitosan sensor to be sensitive to low concentrations of Fe3+, and it is linear responsive in the range of 1.96×10−8 to 2.00×10−5 M. Importantly, this novel sensor may be applied in human serum for direct detection of Fe3+ ion without sample pretreatment. Analysis of 5samples of human serum shows that the average concentration of Fe3+ is 26.95 μM, which is consistent with the results determined by other methods. Moreover, the advantage of chitosan-based assay is that Fe3+ rather than Fe2+ in human serum can be directly measured, avoiding costly, time-consuming and complex process.

► A method of significantly enhanced fluorescence of chitosan has been developed.
► A fluorescence sensor for sensitively detecting Fe3+ ion was fabricated.
► This sensor may be applied in human serum for direct detection of Fe3+ without sample pretreatment.