Background: Previously, glycopeptides antibiotics such as vancomycin, ramoplanin and
an antifungal antibiotic nystatin have been studied for their diagnostic and therapeutic potential.
Objective: To further explore the diagnostic and chemotherapeutic potential of other antibiotics we
have now employed daptomycin, a lipopetide antibiotic and bacitracin, a polypeptide antibiotic in
uptake and vitality tests on human cell lines.
Method: Fluorescent conjugates of bacitracin and daptomycin were synthesized using fluorescein
isothiocynate (FITC) for confocal laser scanning microscopy (CLSM) and fluorescence activated cell
sorting (FACS). The cellular uptake of the synthesized daptomycin and bacitracin conjugates was
studied on seven human cell lines, two healthy and five malignant using CLSM and FACS. To examine
the cell membrane damage caused by the conjugates FACS experiments were carried out using
Results: The uptake pattern was different for both antibiotics for all the cell lines. The cytoplasmic
uptake of daptomycin conjugate was lower than the bacitracin conjugate, resulting in decreased cell
Conclusion: No preferential uptake into malignant or healthy cells was found for the two different
antibiotic conjugates and the uptake patterns were also different between the two antibiotics. However,
the lower cytotoxicity and different uptake mechanism makes daptomycin conjugate a prospective
candidate for further study as a diagnostic agent for various intracellular infections.