Glutathione-responsive PEGylated florfenicol via disulfide linkage enhances antibacterial activity, pharmacokinetics, and biosafety

The introduction of disulfide bond enhanced the bacteriostatic and pharmacokinetics and reduced the side effects of PEGyl- florfenicol. • The glutathione responsive mPEG-SS-florfenicol conjugate is prepared using disulfide bonds as linkers. • The introduction of disulfide bond enhances the self-assembly and antibacterial ability of the conjugate. • Molecular dynamics simulations reveal that responsive conjugate exhibits a stronger interaction with the cell membrane. • The responsive conjugate exhibits superior pharmacokinetic and histopathological characteristics. Developing intelligent and responsive antimicrobial materials is critically important for the sustainable advancement of livestock production. This study prepares a glutathione-responsive mPEG–SS–florfenicol conjugate using disulfide bonds as a linker. A non-responsive conjugate is also synthesized using an alkyl carbon chain as a linker. The structures of both conjugates are characterized through various analytical techniques, including MALDI-TOF MS. The self-assembled microstructures of the responsive and non-responsive conjugates are spherical and lamellar, respectively. At a DTT concentration of 10 mM, 90 % of florfenicol is released from the responsive conjugate within 10 h. The antibacterial activity of the responsive conjugate is 1.6 times greater than that of pure florfenicol at a concentration of 64 μg/mL. At the same concentration, the uptake of the responsive conjugate by E. coli is ten times higher than that of the non-responsive conjugate. Compared with the non-responsive conjugate, the responsive conjugate induces more pronounced damage to the bacterial cell membrane. Molecular dynamics simulations confirm that the responsive conjugate binds to bacterial membranes more rapidly and with lower binding energy. The elimination half-life, maximum concentration (C max ), and area under the curve of the responsive conjugate are 1.3, 1.7, and 2.4 times higher than those of commercial trimethoprim tablets, respectively.