Abstract
Surface imprinting used for template recognition in nanocavities can be controlled and improved by surface morphological changes. Generally, the lithographic technique is used for surface patterning concerning sensing signal amplification in molecularly imprinted polymer (MIP) thin films. In this paper, we describe the effects of silanized silica molds on sensing the properties of MIP films. Porous imprinted poly(MAA–co–EGDMA) films were lithographically fabricated using silanized or non-treated normal silica replica molds to detect 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide as the standard template. The silanized mold MIP film (st-MIP) (Δf = −1021 Hz) exhibited a better sensing response than the non-treated normal MIP (n-MIP) (Δf = −978 Hz) because the imprinting effects, which occurred via functional groups on the silica surface, could be reduced through silane modification. Particularly, two non-imprinted (NIP) films (st-NIP and n-NIP) exhibited significantly different sensing responses. The st-NIP (Δfst-NIP = −332 Hz) films exhibited lower Δf values than the n-NIP film (Δfn-NIP = −610 Hz) owing to the remarkably reduced functionality against nonspecific adsorption. This phenomenon led to different imprinting factor (IF) values for the two MIP films (IFst-MIP = 3.38 and IFn-MIP = 1.86), which was calculated from the adsorbed 2,4-D mass per poly(MAA–co–EGDMA) unit weight (i.e., QMIP/QNIP). Moreover, it was found that the st-MIP film had better selectivity than the n-MIP film based on the sensing response of analogous herbicide solutions. As a result, it was revealed that the patterned molds’ chemical surface modification, which controls the surface functionality of imprinted films during photopolymerization, plays a role in fabricating enhanced sensing properties in patterned MIP films.
Highlights
The molecular imprinting technique is extensively used for various applications such as sorbents and sensors
As a favorable sensing approach, molecular imprinting is widely employed as optical sensors [3], electrochemical biosensors [4], and biomimetic sensors [5,6] as well as is used for drug extraction applications [7]
The lithographic approach is an efficient tool for molecularly imprinted polymer (MIP) structuring on sensing surfaces associated with quartz crystal microbalance (QCM) and could be combined with electro-/photochemical polymerization to fabricate designed imprinted films
Summary
The molecular imprinting technique is extensively used for various applications such as sorbents and sensors. The lithographic approach is an efficient tool for MIP structuring on sensing surfaces associated with quartz crystal microbalance (QCM) and could be combined with electro-/photochemical polymerization to fabricate designed imprinted films. Our group focused on increasing the sensing response of QCM-based MIP sensors by controlling the surface area of MIP films, which were fabricated using colloidal/soft lithography and photo-/electropolymerization [17]. Compared to their planar MIP film counterparts, the structured MIP films exhibited enhanced sensing signal response during a limited period owing to the increased surface area into which the specific template diffused in solution
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