perparamagnetic Nanoparticles for Thermoresponsive Delivery of Camptothec
‫يم جزي ئات دق ي قة عال ية ال م غ ناط ي س ية ت س تج يب ل لحرارة ل تو ص يل ك ام ب توث ي س ين ل‬
Ayat Ahmed Allam
‫آي ات أحمد ع الم‬
Fawzia Sayed Ahmed, Giovanni Pauletti, Dina Fathallah Mohamed
‫ دي نا ف تح هللا محمد‬،‫ جوف ان ى ب ول ي تى‬،‫ف وزي ة س يد أحمد‬
nown to be effective against various cancer types, through targeting the nuclear enzyme topoisomeraseand severe side effects, many efforts have been made to improve these drawbacks, with retaining its an
and irinotecan. But, in spite of the solubility improvement, these CPT derivatives still contain a terminal
ation strategies have been designed for CPT to stabilize and deliver the drug effectively for clinical use.
mprovement of the pharmacological effect by passively delivering chemotherapeutic agents to tumor sit
re toxic effects. The ability to absorb and convert electromagnetic energy into heat has made MIOPs a
ermosensitive materials as an outer shell have resulted in bioresponsive multifunctional nanosystem su
om its carrier can be regulated via the wireless, externally applied alternative magnetic fields. Later, a s
gatively affecting magnetically induced heating properties. However, limited colloidal stability was obtain
dispersed in physiological buffer systems. Particle sizes of 200-300 nm is required to avoid the clearanc
um level of the drug and achieving the passive targeting properties based on the enhanced permeability
e can’t be measured accurately. In the light of the above, the aim of the present study was to modify bot
ication parameters during the lipid coating process on colloidal stability of these prepared nanoparticles.
cles for magnetically induced hyperthermial application in order to effectively facilitate clinical developme
within the outer thermoresponsive phospholipid bilayer. So, the drug will be protected from the rapid hyd
m, those drug-loaded MIOPs have exhibited a prolonged circulation time in-vivo by avoiding the reticuloe
lipid layer as a result of the hyperthermia effect, upon the exposure to external alternative magnetic field
tentially decreased severe toxic effects on healthy tissues. For this, the work of this thesis was divided in
ls with the preparation and characterization of electrostatically stabilized colloidal dispersion of uncoated
hesized MIOPs in order to determine the most stable obtained colloidal dispersion. The factors that poss
l dispersion. These include the ionic concentration of the vehicle in which the particles are dispersed, th
ent concentrations (0.2, 0.1 and 0.02 mg/mL) of MIOPs colloidal dispersions using the commercially av
S, HEPES and different pH values of citrate buffer. The colloidal stability were detected by measuring th
d the dissolution of FeCl3 and FeCl2 in deionized water at a molar ratio of 1:2 under elevated temperatu
nt concentrations (0.2, 0.1 and 0.02 mg/mL) of the synthesized MIOPs colloidal dispersion in citrate buf
cterization of the selected uncoated MIOPs colloidal dispersion: characterizations of the selected uncoa
cles from the synthesis process using both X-ray diffraction (XRD) and selected area diffraction (SAD), d
ated particles over time. Results of this part revealed the following: 1- Citrate buffer at pH 7.4 was prove
e inefficient for further lipid coating process, because of the corresponding large particle size and low ze
rated magnetic behavior hindered their use for further lipid coating process. 4- The most stable colloida
ncentration of 0.02 mg/mL and was found to have small particle size (79.95 ± 1.7 nm), large negative ze
O4 MIOPs: This part includes the preparation and characterization of sterically stabilized colloidal dispe
o the flocculation of the lipid coated nanoparticles were studied. These factors included the phospholipid
comprises the following: 1- Fabrication of sterically stabilized lipid-coated Fe3O4 MIOPs: Phospholipid b
her the cationic DPAB lipid or the anioinc DPPG one, were used for the formation of the outer lipid doub
ere assessed by DSC. The particle morphology and size were investigated using (TEM). The magnetiza
by DLS, the magnetic induced hyperthermia behavior of these lipid coated MIOPs was also monitored f
was studied and compared with the uncoated particles. 3- Effect of plasma on the colloidal stability of th
m plasma from different species (mouse, rat, and human). The particles were first separated magnetically
his part showed that: 1- There was a slight enhancement of the colloidal stability of the lipid coated MIO
selected most stabilized lipid coated MIOPs was obtained by mixing the neutral DPPC with the anionic D
otential value (-19.1 ± 1.3 mv) of those lipid coated nanoparticles when dispersed at the concentration o
retain their colloidal stability as indicated by having the same particle size. However, there was a signific
, the stability of these lipid coated particles can be attributed to the steric stabilizing effect of the branche
particles when dispersed in HBSS (5 months) compared to their dispersion in citrate buffer (6 months), H
tion of serum components, in addition to its known safety for the cell experiments if compared to citrate
f the iron particles and hide them from the immune system resulting in more consistent prolonged biodis
Cell culture study): Drug loading and stimulus induced release studies using the medicated lipid coated
aim of confirming the anticancer efficacy of these nanoparticles. The work in this part included the follow
phospholipid mixture prepared in chloroform. Quantification of the drug loading efficiency was performe
nanosystems were quantified by fluorescence spectroscopy. For the thermal induced release, CPT-loa
water bath. While, the colloidal dispersion containing the medicated particles was exposed for 30 minute
at T-cells, a lymphoblastoid free-floating blood cancer used for leukemic cell line research, have been se
s on the properties of its thermostable luciferase reagent that generates a stable “glow-type” luminescen
sessed to determine the maximum temperature and magnetic field duration that Jurkat cells can be expo
dicated particles (control). The cell viability was ascertained following 72 hour incubation. Dose-depend
ent time exposure to alternative magnetic field on the viability of Jurkat cells treated with CPT-loaded M
cement (p < 0.05) of the percentage of the drug loading efficiency by decreasing the concentration of the
within the first hour, which can be attributed to the softening and consequent melting of the phospholipid
ntage by increasing the time of exposure to a 7.0 mT magnetic field alternating at a frequency of 1.0 MH
alues of the physicochemical parameters of the lipid coated MIOPs after the drug incorporation (p > 0.0
4) for 6 months and for 5 months when dispersed in HBSS (pH 7.4) with non-significant differences obta
oxic effect of the medicated MIOPs by 2.2 folds than that of the free drug. Here the cytotoxic effect is due
lls viability in comparison to 12 minutes exposure. Here the cytotoxic effect is due to the combination of
ost effective condition for killing cancer cells. These results underline the feasibility of using these bioco
ntions in cancer therapy to improve inadequate response to conventional therapeutic regimens.