Synthesis of calcium-aluminium-ciprofloxacin layered double hydroxide – physicochemical properties and evaluation on antibacterial activity and cytotoxicity / Monica Limau Jadam

Layered double hydroxides (LDHs) have been proposed as drug delivery systems of
fluoroquinolones including ciprofloxacin (CPX) to overcome their low bioavailability
and prevent the emergence of resistant bacteria. CPX is used in the treatment of various
bacterial infections. However, there are cases of side effects associated with CPX such
as gastrointestinal irritation, tendon problem and skin cancer. Since these issues have
become a major concern in the pharmaceutical industry, more studies on the alteration
of drug behaviour were carried out to avoid these harmful side effects. In this study,
calcium-aluminium-layered double hydroxide (CAL) carrier with a molar ratio of 3:1
(Ca:Al) was initially synthesized by hydrothermal technique. Subsequently, a
fluoroquinolone antibacterial drug, CPX was incorporated into the interlayer of the
CAL host by anion exchange method to produce calcium-aluminium-ciprofloxacinlayered
double hydroxide (CAC). The successful intercalation was confirmed by
powder X-ray diffraction (PXRD) pattern analysis, Fourier transform infrared
spectroscopy (FTIR), carbon, hydrogen, and nitrogen analysis (CHN),
thermogravimetric and differential thermogravimetic analysis (TGA/DTG), and
inductively coupled plasma-atomic emission spectrometry (ICP-AES). The material
was also characterized by using field emission scanning electron microscope (FESEM),
transmission electron microscopy (TEM), and accelerated surface area and porosity
(ASAP) analysis. Well crystallized nanohybrid was obtained at the concentration of 0.2
M CPX. The basal spacing of CAC (0.2 M CPX) synthesized in this study is 17.3 Å,
which resulted from the expansion of CAL due to the inclusion of CPX in the interlayer
space of the CAL carrier with a loading percentage of 75.9% (w/w). The FTIR spectra
of CAC show resemblance to the peaks of CAL and CPX, indicating the inclusion of
the drug into the CAL interlayers. The release percentages of the drug into phosphatebuffered
saline (PBS) at pH 1.2, pH 4.8, pH 6.8 and 7.4 are 65%, 67%, 58% and 60%,
respectively, and are best described by the pseudo-second order kinetic model.
Cytotoxicity studies of CPX, CAL and CAC on human lung fibroblast (MRC5) cells
and normal mouse embryonic (3T3) cells showed no significant toxicity until 100
μg/mL. The antimicrobial activity of CPX, CAL, and CAC were investigated against
Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus by disc diffusion
method. All tested treatments were found effective against all tested strains and there is
no significant difference between the CPX and CAC as it was similar in their
antibacterial activities. The MICs of the synthesized nanocomposite, CAC against
Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus were found to be
50, 40, and 60 μg/mL, respectively and the MBCs of the nanocomposite against all the
pathogenic bacteria is similar at 5 mg/mL. Therefore, this study proved that CAL
nanocarrier can successfully serve as a controlled release and drug delivery system for
the antibacterial drug, CPX.