Magnetic Dendritic Halloysite Nanotube for Highly Selective Recovery of Heparin Digested from Porcine Intestinal Mucosa

Heparin, as a sulfated polysaccharide found in animal tissues, is a commonly employed clinical anticoagulant. However, the heparin concentration in digested raw materials is very low and difficult to recover at high concentrations. To address this issue and enrich the heparin content that can be purified, we have fabricated novel polyamidoamine (PAMAM) dendrimers functionalized on halloysite nanotubes (HNTs), which were also decorated and magnetized with iron oxide (Fe3O4) nanoparticles to enable magnetic separation for selective, scalable recovery of heparin. Using absorption spectroscopy, the heparin recovery efficiency of HNTs and PAMAM-Fe3O4/HNTs was evaluated and compared the results to Amberlite FPA98 Cl, a commercially accessible resin used in heparin extraction. Our results showed that the PAMAM-Fe3O4/HNTs demonstrated higher efficiency of heparin recovery, both in terms of the capacity and rate of adsorption. We also studied the adsorption mechanism of heparin onto the functional amino groups of PAMAM-Fe3O4/HNTs using X-ray photoelectron spectroscopy and ζ-potential techniques, and the results confirmed the strong electrostatic interaction between the functional groups on the surface of PAMAM-Fe3O4/HNTs and the sulfate groups of heparin. Additionally, we demonstrated that a saturated NaCl solution could be effectively used for the recovery of the PAMAM-Fe3O4/HNTs and heparin adsorption process could be repeated without considerable loss in adsorption capacity. In addition, PAMAM-Fe3O4/HNTs selectively recovered heparin from a real sample, consisting of heparin digested from porcine intestinal mucosa. These results confirm that PAMAM-Fe3O4/HNTs have the potential to be employed as a low-cost, green, and efficient adsorbent for heparin recovery.