Green mechanochemical synthesis of porphyrin-based covalent organic frameworks for electrochemical aptasensing of oxytetracycline

Green synthesis: Mechanochemical synthesis of porphyrin COF with tunable crystallinity, low cost. • Ultra-trace detection: OTC detection limit 0.0138 ng·mL −1 , linear range 0.001–1 ng·mL −1 . • High stability & selectivity: Resists 100× interferences; >92% signal retention after 10 days. • Real-world reliable: River water spike recovery 97–103%, RSD < 3.4%. This study devised a green and cost-effective mechanical grinding approach to successfully synthesize porphyrin-based covalent organic framework (COF) materials with adjustable crystallinity and specific surface area under near-solvent-free conditions. 5,10,15,20-tetra(4-aminophenyl)porphyrin (TAPP) and 2,5-dihydroxyterephthalaldehyde (DTA) were employed as monomers. Through the optimization of experimental conditions, precise control over the ordered structure and pore characteristics of the materials was attained, leading to the formation of a crystalline COF with a high specific surface area and abundant pores. The electrochemical aptamer sensor constructed based on this optimized material demonstrated remarkable detection performance for oxytetracycline. The sensor response current exhibited a favorable linear relationship with the oxytetracycline concentration, characterized by a low detection limit, high selectivity, and excellent stability and reproducibility. In the spiked recovery experiments of actual samples, this sensor also showed extremely high reliability. This research not only offers an efficient sensing platform for the rapid detection of trace oxytetracycline but also paves a new way for the rational design of green-synthesized functional COF materials and their application in the field of electrochemical sensing.