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Development of fluorescent sensor for environmental pollutants from
quenching of novel functional monomers based molecularly
imprinted polymer
Abstract
Nowadays, a large number of environmental pollutants (antibiotics, herbicidses, pesticides, et
al) are wide used in the process of the food cultivation, production and preservation. In order to
detect the trace compounds from complex matrix, determination methods with low sensitivity and
high selectivity remains to be a challenge. In our work, molecular-imprinted polymer sensors were
given fluorescent-responsive feature for rapid and direct sensing of these trace pollutants. Two
novel
fluorescent
compounds,
2-acrylamide-6-methoxybenzothiazole
and
7-acryloxy-4-methylcoumarin were synthesized via a simple one-step reactions, using as both
fluorescent reporter and functional monomer to prepare molecular imprinted polymers for
detecting alachlor and sulfadiazine respectively. Schematic illustration of the process used to
prepare the alachlor-imprinted polymer was shown as a representative in Fig. 1. A particular MIP
can specially bind the target analyte, producing changes in the fluorescence of the sensor (either
quenching or enhancing), with the degree of change correlating exactly to the concentration of the
target analytes. In this manner, binding events on MIPs can be converted into physically detectable
fluorescence signals, and analytes can therefore be measured directly without any additional
treatment or tests. In this way, and the environmental pollutants could therefore be quantified by
converting the physically detectable fluorescence signals. Binding experiments demonstrated that
the fluorescence intensity of the resultant polymer decreased linearly with increases in the
concentration of alachlor in the range of 1–150 μM (Fig. 2) with a detection limit of 0.43 μM and
sulfadiazine in the range 1–40 μM with a detection limit of 0.46 μM respectively. In addition, the
fluorescent sensor exhibited significant selectivity over their potentially competitive molecules.
Finally, the proposed method was successfully applied for the determination of alachlor in corn
seed samples with excellent recoveries ranging from 95.58% to 103.83% (Table 1) and
sulfadiazine in milk samples with excellent recoveries ranging from with excellent recoveries
ranging from 85.73% to 102.11%. The developed method shows that fluorescent MIPs are
expected to be excellent chemosensory materials for the rapid detection of environmental
pollutants.
Fig. 1. Schematic illustration of the process used to prepare the alachlor-imprinted polymer.
Fig. 2. Fluorescent spectra for (a) MIPs, and (b) NIPs, with increasing alachlor concentration in
the acetonitrile. The inset shows the corresponding Stern–Volmer plots.
Table 1. Determination of alachlor in corn seeds.
Concentration taken
( nmol
g-1)
Found (mean, n=3)
( nmol
g-1)
Recovery
%
1
0.96±0.05
96.00±5.00
5
4.81±0.14
96.20±2.80
10
10.34±0.33
103.40±3.30
30
29.98±0.07
99.93±0.23
60
57.35±0.47
95.58±0.78
90
93.45±0.91
103.83±1.01