Post-Synthetic Modification of a Fluorescent Covalent Organic Framework as a Multifunctional Sensor for Efficient Detection of 5-Hydroxytryptamine and Its Metabolite and Latent Fingerprint Identification

Abstract

In this study, a functionalized vinyl-linked 2D fluorescent covalent organic framework (COF) (TMT-TA-COOH) is constructed by post-synthetic modification (PSM) of a TMT-TA COF, which is composed of trimethyltriazine (TMT) and terephthalaldehyde (TA). The fluorescent COF (TMT-TA) has the characteristics of good crystallization and stability, but the dispersibility in water is poor, which requires further PSM. After PSM, the obtained TMT-TA-COOH not only exhibits good dispersibility in water but also displays stronger binding ability to analytes, which presents high sensitivity for quantitative identification of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindole-3-acetic acid (5-HIAA) in water. Moreover, TMT-TA-COOH can specifically recognize 5-HT in serum and 5-HIAA in urine with a fast response, good anti-interference performance, and real-time visualization, which enables the TMT-TA-COOH to be a tool for early detection of neurological diseases and biomarkers for carcinoid tumors. In addition, TMT-TA-COOH is also a good candidate for latent fingerprint (LFP) identification, which has the characteristics of high contrast and low background interference. This work not only provides a promising platform for the sensing application of fluorescent COFs in aqueous solution but also opens up a new way for the detection of LFP information.

Post-synthetic modification of a covalent organic framework via a thiol–ene reaction for improving fluorescence detection and removal of cationic crystal violet carcinogenic dye

“…55 In addition, COF-S-COOH showed better dispersion in water due to the introduction of the hydrophilic carboxyl group, which greatly enhanced its potential for fluorescence detection and removal applications in aqueous solutions. 30…”

“…With the deepening research on covalent organic frameworks (COFs) in recent years, COFs have been applied in the fields of adsorption, 28,29 sensing, 30,31 catalysis, 32 separation, 33 drug transport, 34 batteries, 35 desalination of seawater, 36 and photovoltaics 37 due to their stable covalent structures, abundant multifunctional sites, and large specific surface area. 38,39 Of these, research in sensing and adsorption is relatively well established.…”

Fluorescent covalent organic frameworks for environmental pollutant detection sensors and enrichment sorbents: a mini-review

“…The strategy of post-synthetic modification is now widely used to introduce some hydrophilic groups into COFs, which has the potential to obtain fluorescent COFs with good fluorescence properties and water dispersion. 25,102,103…”

Multifunctional Eu(iii)-modified HOFs: roxarsone and aristolochic acid carcinogen monitoring and latent fingerprint identification based on artificial intelligence

“…28 (iii) Carboxylic acid HOFs contain free carboxyl groups, which can interact with the residual fatty compounds and amino acids in LFPs. 29 In addition, there are massive unpaired and residual hydrogen-bonding donor and acceptor groups in the HOF structures, which enables the incorporation of lanthanide ions (Ln 3+ ) into their frameworks through facile post-synthetic modification (PSM) to prepare Ln@HOFs. 30,31 Ln@HOFs show the advantages of high luminous quantum yield, narrow emission bands, long excitation life, and large Stokes shifts of luminescence.…”