Investigation into the antibacterial activity of covalent organic frameworks as a delivery system of trimethoprim against Escherichia coli and Staphylococcus aureus

Covalent organic framework (COF) materials are one of porous sorbents with the capability to improve bioavailability and solubility of drugs, while also controlling the drug release for profound long-term implications in drug delivery systems. Here, using a facile self-assembly method, COF with high ability to modify the customary formulation of antibiotic drugs including trimethoprim (TMP) is synthesized. The resulting nanoporous COF characterized by different techniques such as field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, BET/BJH, and zeta potential, can be prescribed as an antibiotic against most of bacteria. Antibacterial properties of the TMP encapsulated by COF (TMP@COF) is investigated, leading to significantly lower minimum inhibitory concentrations (1.25 and 2.5 μg/mL) compared to pure TMP (10 μg/mL), which can propose it as a highly efficient nanocarrier against both gram-negative and gram-positive bacteria. The release kinetics of TMP@COF is also studied using zero-order, first-order, Higuchi, and Korsmeyer-Peppas models. Our results indicate that the diffusion kinetics of the COF nanodrug carrier is consistent with the Higuchi model, thus evidencing the possibility of stable TMP diffusion from the porous material.Graphical abstract