ABSTRACT
Objective: To achieve multiple target fishing hook by efficiently grafting polymers containing benzophenone (BP) groups and photochemically coupling molecules in medicines onto magnetic nanoparticles (MNPs). Methods: MNPs attached carbonyl groups (Fe3O4-COOH) were prepared through a hydrothermal process. Then they were modified with DMSA, forming MNPs with thiol groups (Fe3O4-SH). Fe3O4-SH nanoparticles were grafted with polymer containing BP groups by surface-initiated condensation polymerization. Effects of monomer feed ratios and contents on the amounts of BP groups were investigated. The molecules in medicines were covalently coupled onto MNPs via photochemical reactions of BP groups. The contents of coupled molecules were determined by FT-IR and UV-Vis spectra analyses. Results: MNPs with average size of 100 nm were produced, modified with DMSA, and decorated by grafting polymer containing photosensitive BP groups. When the content of monomer containing BP groups was increased in grafting polymerizations, more BP groups were incorporated onto MNPs. This was conductive to the subsequent photo- coupling. FT-IR and UV-Vis spectra analyses confirmed the coupling of molecules in medicines. The active H and steric hinderance of the molecules affected their coupling. Conclusion: The resultant magnetic target fishing hook is ready as a probe for targets identification of traditional Chinese medicine (TCM).
ABSTRACT
A molecularly imprinted film ( MIF) was prepared on the surface plasmon resonance ( SPR) sensor chip for the detection of testosterone. The nanometer imprinted film was synthesized by surface grafting approach. First, the gold sensor chip was modified with an iniferter of benzyl diethyldithiocarbamate to create the “grafting from” polymeric surface. Grafting of the MIF onto the SPR chip was subsequently achieved through ultraviolet light-initiated copolymerization of methacrylic acid ( functional monomer ) and ethylene glycol dimethacrylate ( crosslinker ) in the presence of testosterone as a model template. The template molecules were then removed to form a MIF with specific recognition sites for testosterone. With this iniferter technique , self-aggregation in the reaction solution phase was avoided and grafting polymerization was confined to the exterior of the chip surface. The grafting process was implemented by in situ monitoring with SPR, which permitted the thickness of the film to be easily and strictly controlled. The chip surface modified with a testosterone-imprinted film was characterized by the methods of polarization modulation infrared reflection absorption spectroscopy ( PM-IRRAS ) and atomic force microscopy ( AFM ) . According to the results, testosterone-imprinted film modification of the SPR chip was achieved by the distribution of numerous homogeneous, nanoscale holes on the surface. The testosterone-imprinted film was applied on a SPR sensor chip for the detection of testosterone in the range of 2 . 5 í 10-16 to 2 . 5 í 10-6 mol/L in acetonitrile with the lowest determining concentration of 2. 5 í 10-16 mol/L. Adsorption experiments showed that there were two kinds of binding sites in the MIF, and the linear correlations between the changes in reflectivity and the concentration of testosterone were y=19. 69 + 1. 21x(R2=0. 9913) and y=11. 5 + 0. 45x(R2=0. 9895), respectively. Control experiments utilizing estradiol, estriol, and progesterone as analogues showed impressive selectivity and specificity for testosterone determination. The testosterone-imprinted film reproducibility was evaluated with five cycles of rinsing-rebinding and the RSD was 16 . 8% and 11 . 2% for the SPR angle changes in rinsing and rebinding respectively, demonstrating that the MIF-modified SPR sensor had good reproducibility and repeatability. Finally, the SPR sensor was successfully used to determine testosterone in artificial urine samples with recoveries from 85 . 2% to 92 . 8%.