Yan RY, Lin WH, Lu TL, Chen JL. Conjugated hypercrosslinked polymers imprinted with 3,5-dinitrosalicylic acid for the fluorescent determination of α-amylase activity.
SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023;
291:122383. [PMID:
36682253 DOI:
10.1016/j.saa.2023.122383]
[Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/12/2023] [Accepted: 01/14/2023] [Indexed: 06/17/2023]
Abstract
The discovery of a series of coupling reactions between various building blocks has driven the development of porous organic polymers, but the common usage of expensive and air-sensitive organometallic catalysts and complex procedures in harsh syntheses has limited their expansion. A microporous hypercrosslinked polymer (HCP) was synthesized by polymerizing a naphthalene monomer and a 1,4-dimethoxybenzene crosslinker using Friedel-Crafts alkylation over an FeCl3 catalyst and imprinted with 3,5-dinitrosalicylic acid (DNS). The DNS-molecularly-imprinted HCPs (MIHCPs) were characterized as having IUPAC Type I mesoporosity, a specific surface area of 1134 m2 g-1, a monolayer adsorption capacity of 116 cm2 g-1, pore sizes ranging from 5 to 8.5 Å, amorphous frameworks, and distinctive absorption and emission bands by N2 adsorption/desorption analyses, scanning and transmission electron microscopies, and FTIR, UV-Vis, and fluorescence spectrometries. The π-conjugated imprinted framework endowed the MIHCPs with 405-nm fluorescent emission at a 330-nm excitation and dynamic quenching, which was confirmed by changes in fluorescence lifetime and followed a linear Stern-Volmer plot against 1.0-200 μM DNS template molecules under optimized conditions of a pH 7.0 buffer, an MIHCP concentration of 125 μg mL-1, and a 3.0-min equilibration time. The MIHCPs exhibited a high imprinted factor of 8.7 against nonimprinted HCP and a selectivity of 8.63 against reduced DNS, which enabled fluorometric detection of DNS molecules produced by the hydrolysis of starch with microbial, salivary, and pancreatic α-amylases and the subsequent redox incubation with the DNS oxidant. The fluorometric measurement of α-amylase activity was higher in accuracy and precision (RSD: 2.6-2.8% vs. 3.9-4.0%) than conventional UV-Vis spectrometry because the excellent fluorescent sensitivity and imprinting selectivity of the MIHCP probes enabled the use of higher dilution factors with weaker matrix effects.
Collapse