Fluoroquinolone antibiotic encapsulation in Calcium Phosphate-Nanoliposome for bacteria treatment

MIÑAN, A; RODRIGUEZ, C; DELL ARCIPRETE, ML; GONZALEZ, MÓNICA C.

Carlos Paz

Encuentro; XIII Encuentro Latinoamericano de Fotoquímica y Fotobiología; 2017

Liposomes are self-assembly structures of natural phospholipids which have been under study as drug delivery systems mainly due to their high biocompatibility in terms of composition, size and physicochemical properties [1]. Despite of the fact liposomes are promising for biomedical applications; one of the drawbacks inherent to their structural assembling is the leaking of entrapped molecules before reaching their destiny. Moreover, the liposomes tendency to coalesce, results in a diminution of the efficiency and poorly stable suspensions [2]. As well, the membranes and biological fluids interaction provoke mechanical stress on liposomes designed for drug delivery. The coating of liposomes with biocompatible and biodegradable materials as calcium phosphates (CaP) [3,4] brings stability, rigidity and biocompatibility prolonging the circulation time in biological media. Fluoroquinolones (FQ) are synthetic antibiotics with a broad action against pathogens like Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Escherichia coli, etc [5]. The search for a nanostructured system that protects the FQ from external effects and delivers antibiotics in vicinity of pathogens is fundamental to diminish the problems associated with their susceptibility in biological media.In this work we developed a nanovehicle based on 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) liposomes with a CaP-coating which encapsulate fluoroquinolone drugs, levofloxacin (LX) or ciprofloxacin (CX) (named CaPLiLX and CaPLiCX, respectively), for their use as antibiotic controlled delivery devices. The size and shape of the nanoliposomes and effect of CaP-coating on the stability was evaluated through electronic microscopy techniques and electrophoretic mobility measurements. The incorporation of FQ in the nanovehicles was investigated using the characteristic emission peaks and emission lifetimes of the drugs. The growth inhibition of bacterials smears of S. aureus was studied in the presence of nanovehicles.Coated- liposomes with diameters bellow 100 nm were succesfully obtaneid (see inset in the figure). The emission maxima of the antibiotics encapsulated in coated nanoliposomes (see main figure) present a blue shift compared to the corresponding drugs in phosphate buffer solution (PBS, pH 7.4). The result supports the incorporation of LX and CX in the nanoliposomes. The fluorescence decay of LX and CX 6µM PBS solutions was well fitted to a monoexponential function with fluorescence lifetime  = 1.30 ns for CX and  = 6.23 ns for LX which is in agreement with the previous reported data. On the other hand, CaPLiLX and CaPLiCX traces were well-fitted to a tri-exponential decays which include a < 1 ns lifetime attributed to the light scattering of the CaP-coated nanoliposomes. The second fluorescence lifetimes were assigned to drugs aggregation and protonation in liposomes environment, which was also suggested from absorption spectra for both drugs. The third values were consistent with the increased lifetime for drugs molecules confined in hydrophobic environments.