Sequential Assembly Enabled Surface Precise Imprinting on Janus Nanosheets for Highly Specific Separation of Adenosine 5'-Monophosphate

Abstract

Precise control of imprinting processes and reasonable selection of molecularly imprinted polymers’ (MIPs) carriers are essential for realizing highly selective and fast separation. In this work, Janus polymer nanosheets (J-PNs) with different wettabilities on two sides were synthesized by self-polymerizing dopamine based on octadecylamine (ODA) lamellae with a bilayer structure, followed by a sequential imprinting assembly of low pKa boronic acid and pyrimidine base monomers on the hydrophilic side of J-PNs to prepare Janus imprinting sorbents (J-MIPs) for highly specific separation of adenosine 5'-monophosphate (AMP). The sequential assembly strategy integrated two different functional monomers together to simultaneously interact with the surrounding template AMP molecule and to precisely control the imprinting site orientation, enabling the resulting J-MIPs with strong and specific binding toward AMP. Janus amphiphilic J-MIPs can be well fixed at the dodecane/water interface, which was benefit for their fast recycle and simple regeneration, and the uptake amount of the fifth adsorption/elution cycle was 86.08% of the first one. The equilibrium time and maximum adsorption capacity of tailor-made J-MIP were 4.0 h and 13.69 μmol g -1 at 298 K, respectively. Taking the advantage of cooperative multi-point interaction, binding sites with high affinity to AMP accounted for about 76.71% of the total sites, and the high imprinting factor (2.182) of the J-MIP against non-imprinted counterpart was observed. In addition, 61.30% of AMP in spiked human serum sample can be selectively extracted by J-MIPs, due to the highly specific receptor sites from sequential imprinting assembly.

Keywords: Molecularly imprinted polymers (MIPs), Janus nanosheets, Precise imprinting, Sequential assembly, Selective separation adenosine 5'-monophosphate (AMP)