Development of a new simple spectroscopic determination coupled acid-motivated delivery system based on fluorescence turn-off MSNs@MPA-ZnS QDs for infection

Abstract

A pH-sensitive quantum dots (QDs) gatekeeper drug delivery system was proposed for gentamicin (GEN). Mesoporous silica nanoparticles (MSNs), as a biocompatible and popular vehicle with unique loading efficiency in drug delivery systems, were used as GEN nanocarriers. Acid-decomposable 3-mercaptopropionic acid capped-ZnS QDs (MPA-ZnS QDs), biocompatible and water-soluble nanoparticles, have been employed to sealed the nanopores to obstruct premature drug (GEN) release. Encapsulation efficiency (EE = 73.5% ± 1.3) and drug loading (DL = 22.8% ± 0.33) of GEN loaded MSNs was estimated. The release process was investigated in phosphate buffer saline (PBS) (pH = 7.4) and a citrate buffer solution (pH = 5.4) by using a simple spectroscopy (purple GEN-ninhydrin complex) technique for 20 days. At stimulated natural pH in PBS, pores were sealed with MPA-ZnS QDs, in return, under acidic conditions like bacteria grows environment, dissociation of MPA-ZnS QDs occurred, the pores open and the drug molecules diffuse to the environment. The release of the drug was studied in the presence of Escherichia coli (strain 0157:H7) and Staphylococcus aureus (strain ATCC:25923) bacteria. The amounts of minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) parameters were measured. Calculated microbial parameters for GEN loaded MSNs in the presence of the two spices were less than these of GEN loaded MSNs@MPA-ZnS QDs. So, MPA-ZnS QDs as the pH-sensitive gatekeepers can control the drug-releasing. • Nano-mesoporous silica and MPA- ZnS QDs synthesized by green methods. • MPA-ZnS QDs acted as gatekeepers for GEN loaded MSNs. • Well, burst and sustained release were observed for 20 days. • In vitro amount of MIC and MBC surveyed for Escherichia coli and Staphylococcus aureus bacteria.