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. 2016 Oct 14;16(10):1697.
doi: 10.3390/s16101697.

Selectivity Enhancement in Molecularly Imprinted Polymers for Binding of Bisphenol A

Noof A Alenazi  1 , Jeffrey M Manthorpe  2 , Edward P C Lai  3
Affiliations

Selectivity Enhancement in Molecularly Imprinted Polymers for Binding of Bisphenol A

Noof A Alenazi et al. Sensors (Basel). .

Abstract

Bisphenol A (BPA) is an estrogen-mimicking chemical that can be selectively detected in water using a chemical sensor based on molecularly imprinted polymers (MIPs). However, the utility of BPA-MIPs in sensor applications is limited by the presence of non-specific binding sites. This study explored a dual approach to eliminating these sites: optimizing the molar ratio of the template (bisphenol A) to functional monomer (methacrylic acid) to cross-linker (ethylene glycol dimethacrylate), and esterifying the carboxylic acid residues outside of specific binding sites by treatment with diazomethane. The binding selectivity of treated MIPs and non-treated MIPs for BPA and several potential interferents was compared by capillary electrophoresis with ultraviolet detection. Baclofen, diclofenac and metformin were demonstrated to be good model interferents to test all MIPs for selective binding of BPA. Treated MIPs demonstrated a significant decrease in binding of the interferents while offering high selectivity toward BPA. These results demonstrate that conventional optimization of the molar ratio, together with advanced esterification of non-specific binding sites, effectively minimizes the residual binding of interferents with MIPs to facilitate BPA sensing.

Keywords: bisphenol A; diazomethane; non-specific binding sites; site-selective chemical modification; treated molecularly imprinted polymers.

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Conflict of interest statement

The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

Figures

Scheme 1
Scheme 1
Methylation of carboxylic acid functional group with diazomethane. R represents the molecularly imprinted polymer or non-imprinted polymer matrix.
Figure 1
Figure 1
Percent binding results of bisphenol A (BPA), diclofenac (DFC) and metformin (MF) (individually and in mixture) and electrophoretic mobility for each MIP prepared with a different mole % of BPA. For clarity, error bars are represented by the size of symbols.
Figure 2
Figure 2
Percent binding results of BPA, DFC and MF (individually and in mixture) and electrophoretic mobility for each diazomethane-treated molecularly imprinted polymers (TMIP) prepared with a different mole % of BPA. For clarity, error bars are represented by the size of symbols.
Figure 3
Figure 3
Percent binding results of BFN (individually) for each MIP and TMIP prepared with a different mole % BPA. For clarity, error bars are represented by the size of symbols.
Figure 4
Figure 4
HPLC analysis of a mixture of MF (200 ppm) at 2.5 min, DFC (200 ppm) at 3.6 min, BFN (200 ppm) at 4.1 min and BPA (100 ppm) at 6.6 min. Mobile phase: CH3CN/MeOH/DDW (1:1:1 v/v); flow rate, 0.8 mL/min; UV detection at 200 nm.
Figure 5
Figure 5
Scanning electron microscopy images of MIP, NIP, TMIP and TNIP particles.
Figure 6
Figure 6
Dynamic light scattering analysis of MIP, NIP, TMIP and TNIP particles.
See this image and copyright information in PMC

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