Discontinuous cooperative imprinting idea based on MXene-nanocomposite membrane for high structurally stable recognition and separation of shikimic acid

Ti3C2Tx (MXene) has attracted wide research interest for application in various fields due to its rich surface chemistry and 2D multilayer structure. However, its application remains challenging due to its oxidative fragility. Here, Polydopamine (PDA) act as both the functional monomer and crosslinker, could self-polymerize to form a stable multifunction hybrid coating on MXene surfaces, which enhances the antioxidant properties of the MXene while form the first SA-imprinted sites. During the second imprinting process, the PDA-based first SA-imprinted recognition layer acted as the "anchor" to trigger the second SA-imprinted layer (sol–gel boronate affinity imprinting layer). Benefiting from the above mentioned discontinuous cooperative imprinting strategy, an efficient SA dual-imprinted sites was constructed on the surface of MXene-based molecularly imprinted membrane(P-MBMs). Such cooperative imprinting strategy could generate highly specific and strong binding sites for the template molecule. Adsorption isotherm and dynamics, permeation selectivity, and stability were studied, with ideal rebinding ability for SA (363.29 g m−2) and permselectivity factors (βCatechol/SA = 2.40, βP-HB/SA = 5.50, βP-NP/SA = 7.54), respectively. In-situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) analysis revealed that the high selectivity of P-MBMs for SA was mainly realized by the SA dual-imprinted sites constructed on the membrane. In addition, dynamic penetration test was first used to to verify the stability of the P-MBMs to specifically recognize the target molecule in this work. Compared to one-step imprinting approaches, the proposed discontinuous cooperative imprinting strategy would offer precise recognition sites, multiple strengthening of SA-imprinted sites could improve the selective separation performance of P-MBMs.