Photonic and magnetic dual responsive molecularly imprinted polymers: preparation, recognition characteristics and properties as a novel sorbent for caffeine in complicated samples

We demonstrated the construction and characteristics of photonic and magnetic dual responsive molecularly imprinted polymers (DR-MIPs) prepared by combination of stimuli-responsive polymers and a molecular imprinting technique. The resultant DR-MIPs of Fe3O4@MIPs exhibited specific affinity for caffeine and photoisomerization induced reversible uptake and release of caffeine upon alternate UV and visible light irradiation. With irradiation at 365 nm, 62.5% of the receptor-bound caffeine was released from the DR-MIPs back into solution. Subsequent irradiation with visible light caused 93.6% of the released caffeine to be rebound by the DR-MIPs. The novel DR-MIPs were used as a sorbent for the enrichment of caffeine from real water and beverage samples. Recoveries ranging from 89.5-117.6% were achieved. The magnetic property of DR-MIPs provided fast and simple separation while the photonic responsive property offered simple template elution with the assistance of UV-Vis irradiation. The simple, rapid and reliable DR-MIPs based method proved potentially applicable for trace caffeine analysis in complicated samples.