Facile Fluorescence Monitoring of Gut Microbial Metabolite Trimethylamine N-oxide via Molecular Recognition of Guanidinium-Modified Calixarene

Abstract

Detection and quantification of trimethylamine N -oxide (TMAO), a metabolite from gut microbial, is important for the disease diagnosis such as atherosclerosis, thrombosis and colorectal cancer. In this study, a novel method was established for the sensing and quantitative detection of TMAO via molecular recognition of guanidinium-modified calixarene from complex matrix. Methods : Various macrocycles were tested for their abilities to serve as an artificial TMAO receptor. Using the optimized receptor, we developed an indicator displacement assay (IDA) for the facile fluorescence detection of TMAO. The quantification of TMAO was accomplished by the established calibration line after excluding the interference from the various interfering substances in artificial urine. Results : Among various macrocycles, water-soluble guanidinium-modified calix[5]arene (GC5A), which binds TMAO in submicromolar-level, was identified as the optimal artificial receptor for TMAO. With the aid of the GC5A•Fl (fluorescein) reporter pair, TMAO fluorescence “switch-on” sensing was achieved by IDA. The fluorescence intensity increased linearly with the elevated TMAO concentration. The detection was not significantly interfered by the various interfering substances. TMAO concentration in artificial urine was quantified using a calibration line with a detection limit of 28.88 ± 1.59 µM, within the biologically relevant low µM range. Furthermore, the GC5A•Fl reporter pair was successfully applied in analyzing human urine samples, by which a significant difference in fluorescence response was observed between the [normal + TMAO] and normal group. Conclusion: The proposed supramolecular approach provides a facile, low-cost and sensitive method for TMAO detection, which shows promise for tracking TMAO excretion in urine and studying chronic disease progression in humans.

Noninvasive and Individual‐Centered Monitoring of Uric Acid for Precaution of Hyperuricemia via Optical Supramolecular Sensing

“…On account of the screening results for UA artificial receptor from macrocyclic library, the GC5A·Fl reporter pair was selected in fluorescence “switch‐on” mode, which was validated to possess a desirable association constant ( K a = (5.0 ± 1.0) × 10 6 m −1 ) by the fluorescence titration and UV–vis titration. [ 33,35 ] Moreover, UA did not interfere with the fluorescence intensity of Fl in the range of 0–447.08 × 10 −6 m (Figure S13A, Supporting Information). As shown in Figure A, UA can competitively associate with GC5A against Fl in a concentration‐dependent manner, indicating the observation of a relatively strong binding affinity ((2.87 ± 0.23) × 10 5 m −1 ) between UA and GC5A (Figure 1B).…”

Metal ion-responsive nanocarrier derived from phosphonated calix[4]arenes for delivering dauricine specifically to sites of brain injury in a mouse model of intracerebral hemorrhage

“…Among the macromolecules, calixarene is considered to represent the third-generation of host-guest supramolecular chemistry [51]. Calixarene and its derivatives have been reported to have antiviral, antibacterial, antifungal, antitubercular, and anticancer activity [52].…”

Rapid Detection of Gut Microbial Metabolite Trimethylamine N-Oxide for Chronic Kidney Disease Prevention

“…An artificial urine solution was prepared according to previous reports [ 14 , 17 ], namely, by dissolving urea (9.1 g), sodium chloride (3.7 g), sodium phosphate (monobasic, 2.4 g), potassium chloride (2.2 g), creatinine (1.0 g) and BSA (25 mg) in 500 mL DI-H 2 O. The pH of the artificial urine solution was adjusted to pH 6.0 with HCl and stored at 4 °C.…”

“…However, its practical application has been limited due to the need to separate amine analytes and the lack of simplicity, efficiency, and portability of these reductions. Wang and coworkers explored a facile fluorescence assay for TMAO quantification on the basis of an indicator displacement assay (IDA) using water-soluble guanidinium-modified calix [ 5 ] arene (GC5A) as an artificial receptor [ 14 ]. However, its practical application has been limited because the indicator displacement may be affected by other substances in real urine samples.…”