Efficient visual detection and adsorption of tetracyclines using zinc porphyrin-based microporous organic networks

In the present work, a novel zinc-porphyrin-based microporous organic networks (Zn-MONs) were synthesized via facile solvothermal for the detection of tetracyclines (TCs). Zn-MONs, with their well-designed network structure featuring a significant specific surface area and appropriately sized pores, effectively facilitated the enrichment of TCs, resulting in a notable enhancement in sensitivity. Also, in the presence of TCs, Zn-MONs with TCs induced emission of yellow-green fluorescence located at 522 nm due to aggregation. Under the optimal conditions (excitation wavelength of 370 nm, pH = 7.0 in the HEPES-NaOH buffer solution, 0.2 g·L-1 Zn-MONs, and reaction time of 10 min), the Zn-MONs sensing system exhibited good sensitivity with limits of detection (LOD) of 10.6 and 35.5 nmol·L-1 towards tetracycline (TC) and chlortetracycline (CTC), respectively. Moreover, Zn-MONs demonstrated robust selectivity towards TC and CTC, even in the presence of diverse interfering analytes (e.g., ions, antibiotics and proteins). In addition, the good spiked recoveries for TCs detection (96.35 ∼ 99.85 %/0.47 ∼ 2.48 % for TC and 87.20 ∼ 101.11 %/0.53 ∼ 2.70 % for CTC, respectively) indicated the great potential of Zn-MONs in real-world condition (tap water and lake water). Furthermore, the feasibility of test paper embedded with Zn-MONs for sensing TC was explored. The increase in TCs concentration deepened the yellow-green color of test paper. As such, the constructed test paper can semi-quantitatively detect TC and CTC in water samples. Meanwhile, Zn-MONs had good adsorption capacity for TC through monolayer adsorption with the experimental maximum adsorption capacity of 69.62 mg·g−1. Zn-MONs had good reusability toward TC at least five adsorption–desorption consecutive cycles. The outcomes collectively showcase the successful fluorescence detection and removal of TCs using Zn-MONs, highlighting the broader potential of MONs in fluorescent sensor applications.