Extraction of crocin from saffron using nanomagnetic molecularly imprinted polymer

Saffron is the dried stigmas of Crocus sativus and the most expensive spice used in industry, with many different uses as drug. The saffron and its coloured carotenoids (crocins) have memory improving properties anti Alzheimer, antidepressant, antioxidant, antitumor and anti-cancer effects. Due to these reasons, introducing and establishing a simple and effective method for extraction of crocins from its natural sources would be necessary and useful [1,2]. In the current study, a new strategy for the extraction of crocin from saffron has been employed by using nanomagnetic molecularly imprinted polymer (MMIP) as sorbent. MMIPs due to the super paramagnetic properties, good chemical and physical stability and simple synthesis methodology. They have the characteristics of the magnetic adsorbents property, high adsorption capacity to template molecule, re-usability, selectivity and high efficiency. These materials have been widely used in the different fields such as chemical, biological and medical science [3,4]. The MMIPs were synthesized as follows: firstly, magnetic Fe3O4 nanoparticles (NPs) were prepared by the co-precipitation of Fe2+and Fe3+ ions in an ammonia solution. The Fe3O4 nanoparticles modify with SiO2 by TEOS shell (Fe3O4@SiO2) was prepared and then surface of magnetic nanoparticles was functionalized with 3-(trimethoxysilyl) propyl methacrylate (MPS). After the well-defined MMIPs for crocin were further fabricated on the surface of Fe3O4@SiO2@MPS using gentiobiose as template molecule, methacrylic acid (MAA) as functional monomer, 2,2-azobisisobutyronitrile (AIBN) as Initiator and ethylene glycol dimethacrylate (EGDMA) as cross-linking agent. The prepared nanomagnetic molecularly imprinted polymer were characterized and confirmed by FT-IR, XRD, TGA, SEM and VSM. For achieving optimal pre-concentration and reducing nonspecific interactions, various parameters affecting the extraction efficiency such as sorbent amount, eluting solvent, sample concentration and contact time have been investigated and established. The resulting MMIP showed high adsorption capacity, proper selectivity and fast kinetic binding for the template molecule. The results of re-binding experiments indicated that the MMIPs had fast adsorption kinetics and could reach binding equilibrium during 45 min and the adsorption capacity of the MMIPs was 9.76 mg/g. This is higher than that of the corresponding non imprinted polymer (MNIP).