ABSTRACT
This study reports the construction of a novel SPME fiber based on chitosan and glutaraldehyde as coating material composites combined with high-performance liquid chromatography with an ultraviolet detector (HPLC-UV) for extraction and detection of phenobarbital. In this technique, the chitosan biopolymer, as a new coating of SPME fiber, was produced on the stainless-steel wire, using glutaraldehyde and phenobarbital as cross-linker and template, respectively. For comparison, a nonimprinted polymer was created using the same procedure to evaluate fiber selectivity (but without the addition of phenobarbital). The SPME-MIP fiber coating was characterized by field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermal gravimetric analysis. The efficiency of fiber was then improved by adjusting the impact of numerous factors such as pH, extraction time, desorption time, desorption solvent, and stirring rate. The results showed that the proposed fiber has a linear range of 0.01-4 µg·mL-1, and detection limit of 7.5 ng·mL-1. The average recoveries in the four concentration levels for the spiked river and well water samples were 95.7 and 95.3%, with relative standard deviations of 3.8 and 5.9% for single fiber and between fibers, respectively.
ABSTRACT
This article describes the synthesis and properties of novel imidazole-based aromatic polyimides (PIs) containing bulky groups from direct polycondensation of two diamines with 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) and (hexafluoroisopropylidene)diphthalic anhydride (6FDA). The structure-property relationship of the prepared samples was fully determined via FT-IR, 1H and 13C NMR and elemental analysis (CHN) techniques. The inherent viscosity values of the polyimides ranged from 0.51 to 0.73 dL g-1. These PIs showed glass transition temperatures ranging from 273 to 306 °C, and 10% mass loss temperatures within the range of 478-504 °C in a N2 atmosphere. High transparency with a UV-visible absorption cut-off wavelength was found to range between 285 and 300 nm. Good antimicrobial activity can be correlated with the presence of xanthene and imidazole units into the main structure of PIs. Next, SiO2 nanoparticles as inorganic nanoparticles were added to one of the synthesized polyimides (BTDA-PIb), causing changes in the attributes of both the nanoparticles and PI. The data obtained from examining the properties of the prepared BTDA-PIb/HBP@SiO2 demonstrated increased heat resistance, photoluminescence intensity, and antimicrobial inhibition compared to pure PI. Also, in this article, the polymeric samples as adsorbents were evaluated for extraction of heavy metal ions (Hg2+ and Co2+) from water sources.
ABSTRACT
Electrochemiluminescence resonance energy transfer (ECL-RET) assay as an efficient analytical technique has aroused considerable interest in recognition and biosensing. In the present study, a novel self-enhanced ECL-RET of Ru(bpy)2(phen-NH2)2+ as an efficient luminophore to the MoS2 nanosheets as effective quencher was designed for CA19-9 antigen analysis. Herein, the graphene oxide grafted hyperbranched aromatic polyamide (GO-HBP) with high loading ability for Ru-complex was used as the sensing platform, while amine-rich nitrogen-doped carbon nanodots (NCNDs) which covalently linked to Ru(bpy)2(phen-NH2)2+ applied as co-reactant for enhancing of anodic ECL signal response. In this approach GO-HBP-Ru-complex-NCND-anti-CA19-9 Ab exhibited amplified ECL emissions ("on" state) and with formation of sandwiched immunocomplex between, immobilized CA19-9 Ab, CA19-9 antigen and MoS2 nanosheets modified with CA19 9 antibody, the ECL response of luminophore was efficiently quenched ("off" state). The signal response was doubly amplified by covalent attachment of more luminophore, co-reactant and CA19-9 antibody with hyperbranched aromatic polyamide. On the basis of all above features, the ECL intensity of Ru-NCND decreased with the increase of the concentration of CA19-9 antigen in a wide linear range of 2 mU mL-1- 50 U mL-1 with the detection limit of 0.25 mU mL-1 (S/N = 3). The application of the fabricated ECL-RET immunosensor for determination of CA19-9 antigen in human serum samples was appraised that the satisfactory results were found to be in admissible accord with those gained with the reference method (ELISA assay).The suggested method opens up a novel avenue for expanding high-performance ECL-RET immunosensors cancer markers detection in clinical monitoring.
