Abstract
Self-assembly and molecular imprinting technologies are very attractive technologies for the development of artificial recognition systems and provide chemical recognition based on need and not happenstance. In this paper, we employed a β-cyclodextrin derivative surface acoustic wave (SAW) chemical sensor for detecting the chemical warfare agents (CWAs) sarin (O-Isoprophyl methylphosphonofluoridate, GB). Using sarin acid (isoprophyl hydrogen methylphosphonate) as an imprinting template, mono[6-deoxy-6-[(mercaptodecamethylene)thio]]-β-cyclodextrin was prepared by self-assembled method on one of the SAW oscillators. After templates’ removal, a sensitive and selective molecular imprinting (MIP) monolayer for GB was prepared. Electrochemical impedance spectroscopy and atomic force microscope (AFM) were used to characterize this film. Comparing the detection results to GB by MIP film and non-MIP film, the molecularly imprinting effect was also proved. The resulting SAW sensor could detect sarin as low as 0.10 mg/m3 at room temperature and the frequency shift was about 300 Hz. The response frequency increased linearly with increasing sarin concentration in the range of 0.7 mg/m3~3.0 mg/m3. When sarin was detected under different temperatures, the SAW sensor exhibited outstanding sensitivity and reliability.
Highlights
Chemical warfare agents (CWAs) are powerful weapons and a threat to civil safety
Given the high mass-sensitivity of the surface acoustic wave (SAW) sensor, the thickness of the self-assembled molecular imprinting (MIP) film was estimated by measuring the frequency shift with Sauerbrey formula as follows [7,12]: (1)
When the Au coating area of the SAW oscillator is not coated with mono[6-deoxy-6-[(mercaptodecamethylene)thio]]-β-CD, the RMS[Rq] of Au is 0.498 nm, and its surface is orderly; Upon self-assembly of the MIP film, RMS[Rq] rises to 1.604 nm, which is about 3 times that of Au, so the Au surface becomes much rougher
Summary
Chemical warfare agents (CWAs) are powerful weapons and a threat to civil safety They are extremely hazardous and potentially lethal. As these agents can be dispersed as a gas, liquid, aerosol or powder, developing methods to detect CWAs at very low limits as quickly as possible is very important to ensure civilian safety [1,2,3]. The preparation of a MIP film is based on a cross-linking process using functional monomers that have a specific interaction with templates (print molecules). Functionalized cyclodextrins have been studied for various applications, such as enzyme mimics, separation, and drug delivery [15,16,17], few reports about cyclodextrin as a sensitive film for SAW sensor detection of warfare agents have been published [18]. Sarin acid was selected as a template modifying β-cyclodextrin through upper and lower rim functionalization, and a SAW sensor with high selectivity and sensitivity toward GB was fabricated
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