Preparation of Controllable Non-covalent Functionalized Carbon Nanotubes with Metalloporphyrin-Sn Network and Application to Protein Adsorption

In order to enhance the adsorption of protein, a one-step metallization of porphyrin and a novel metalloporphyrin-Sn network non-covalently ftmctionalized multi-walled carbon nanotube composite (MMPT), were developed only by a simple one-pot solvothennal method. Under solvothennal conditions, Sn entered the meso-tetralds(4-carboxyphenypporphine (TCPP) macrocycle to metallic the porphyrins and formed SnTCPP. Meanwhile, Sn, as a crosslinker, bridged the SnTCPP molecules around the surface of multi-walled carbon nanotubes (MWCNTs) to form a uniform and continuous SnTCPP-Sn network layer through self-assembly without any pre-modification for TCPP and MWCNTs. Then, through pi-pi stacking, multilayers of SnTCPP-Sn network can be formed via layer-by-layer self-assembly, as well as MMPT with controllable layer thickness. With this synthetic strategy, the sites of porphyrin on the MWCNTs surfaces were found continuous and evenly distributed, which enabled the controllability of layer thickness as well as the site density by adjusting the MWCNTs/TCPP ratio. The morphology, structure and properties of MMPT were characterized comprehensively by scanning electron microscope (SEM), transmission electron microscope (TEM) and its energy-dispersive X-ray spectroscopy (EDS), ultravioletvisible (UV-Vis) spectroscopy, Fourier transform infrared spectrophotometer (FT-IR), and zeta potential. In addition, the effects of various factors on its adsorption properties and the interaction between MMPT and bovine serum albumin (BSA) were investigated. When the mass ratio of MWCNTs was 1.0 and the concentration of BSA was 1.5 mg.g(-1), the effective adsorption sites per unit mass of MMPT reached the maximum, resulting in the maximum adsorption capacity of MMPT to BSA (651.4 mg.g(-1)), and the adsorption equilibrium can be reached in only 5 min. Compared with other adsorbents, MMPT showed high adsorption capacity for BSA under the optimal carbon nanotube ratio and adsorption conditions. In addition, MMPT also exhibited a good adsorption affinity for other proteins like bovine hemoglobin (BHb) and lysozyme (Lyz), which has a wide application prospect in protein adsorption, drug delivery, sensing and so on.