Fabrication And Performance Of The Alizarin Red S (ARS)/Layered Double Hydroxide (LDH) Ultrathin Films

In this study, based on the layer-by-layer (LBL) assembly technique, new facile, economical ultrathin films (UTFs) are developed. The UTFs have been fabricated by combining the alizarin red S (ARS) with layered double hydroxide (LDH) nanoparticles. In the experiment, we used the phenylboronic acid (PBA) and boric acid (BA) to modified the UTFs, respectively and studied their structures and morphologies. In this paper, we also study the UTFs as probes in the applications of the electrochemical sensor and fluorescent sensor. The mainly results are as follows:1. In this study, new facile, economical and electrochemical ultrathin films (UTFs) for detection of glucose are developed through the layer-by-layer (LBL) assembly technique. The UTFs have been fabricated by combining CoAl layered double hydroxide (LDH) nanoparticles with the ARS and the ARS-PBA adduct, respectively, to getting the (ARS/LDH)n UTFs and the(ARS-PBA/LDH)n UTFs. The UTFs display a uniform morphology and a periodic layered structure. When n=10, the UTFs show the best electro-chemical activities. Compared with (ARS/LDH)n UTFs, (ARS-PBA/LDH)n shows better electro-chemical activities, stability, and repeatability. The UTFs as an electrochemical sensors detect the concentration of the glucose. The two sensors show different electro-catalytic activities. The results reveal that (ARS/LDH)n show lower detection limit (0.5 nM) and higher sensitivity (80?A/nM); (ARS-PBA/LDH)n show wider detection range (0?1.00?M) and higher accuracy (R2=0.9936). Meanwhile, the possible interfering substances also were measured, the results demonstrated that the sensor has a good selectivity.2. In this study, new facile, economical and fluorescent ultrathin films (UTFs) for detection of tiopronin are developed. The UTFs have been fabricated by combining the alizarin red S-boric acid adduct (ARS-BA) with MgAl layered double hydroxide (LDH) nanoparticles through the layer-by-layer (LBL) assembly technique. The UTFs display a uniform morphology and a periodic layered structure. Using ARS as a probe, which does not emit fluorescence by itself but displays fluorescence when complexed with boron, the assembled ARS-BA/LDH UTFs display a high luminescence response to tiopronin. In the presence of Cu2+, the fluorescence of UTFs was quenched, which is attributed to the complexation between Cu2+ and ARS. Upon adding tiopronin to the UTF-Cu2+ system, tiopronin would form a complex with Cu2+ preferentially, leading to the increased fluorescence of UTFs. Based on the above mechanism, a turn-on fluorescent ensemble for tiopronin is developed. A linear response was obtained in the range of 0-80 ng/mL, with a detection limit of 0.47 ng/mL. Compared with ARS and other analytes, the tighter binding of tiopronin to Cu2+ led to an assay with high specificity. Therefore, this work provides a facile LBL strategy for the fabrication of a solid state sensor based on ARS dye for detection of tiopronin.