Development of fluorescent molecularly imprinted nanoparticles for analysis of nitroaromatic compounds and dioxin

Fluorescent molecularly imprinted materials have attracted the interest of researchers in recent years, due to their ability not only to selectively bind target analytes but also to generate detectable optical signals as a result of molecular binding.

Here we report the development of fluorescent nano-molecularly imprinted (F-nanoMIPs) used as plastic antibodies in assays, as material for sensing and as recognition elements in chemosensors for small organic molecules (e.g. toxins, environmental pollutants). Four F-nanoMIPs (A, B, C and D) were synthesised for several different templates 4-nitroaniline (4-NA), 2,4-dinitroaniline (2,4-diNA), 2-aminomethyl-1,4-benzodioxane and 1-aminomethyl-7-8-dichlorodibenzo-p-dioxin (AMDCDD).

These F-nanoMIPs were prepared using a solid phase approach by mixing the fluorophore N-2-propenyl-(5-dimethylamino)-1-naphthalene sulphonamide and methacrylic acid (MAA) as monomers. Both F-nanoMIPs A and B were successfully developed to detect and quantify the concentration of 4-NA and 2,4-diNA respectively (Chapter 2). 2-aminomethyl-1,4-benzodioxane was used as a dummy template for the preparation of F-nanoMIPs C for 2,3,7,8- tetrachlorodibenzodioxin (TCDD) detection (Chapter 3). The selectivity experiments of F-nanoMIPs C showed a good specificity toward the imprinted template, but poor selectivity was also showed for the actual target TCDD. An additional challenge was to modify analogue to improve molecular recognition by the TCDD- targeting fluorescent chemosensor. AMDCDD was synthesised to be used as a dummy template instead of TCDD for development of F-nanoMIPs D. Even though F-nanoMIPs D system offered an unsatisfactory selectivity toward the actual target TCDD, this recognition was better than three other analogues. These initial results could be useful in designing F-nanoMIPs for selective and efficient sensing of TCDD by future optimisation of F-nanoMIPs D composition.

Compared to natural antibodies, nanoMIPs show superior stability, are less expensive and faster to produce, yet have similar specificity and affinity. Consequently, F-nanoMIPs could provide invaluable tools in the development of a new generation of sensors suitable for routine environmental monitoring.