Moxifloxacin Liposomes:Effect of Liposome Preparation Method on Physicochemical Properties and Antimicrobial Activity against Staphylococcus epidermidis

The aim of this study was the development of optimal sustained-release moxifloxacin (MOX)-loaded liposomes as intraocular therapeutics of endophthalmitis. Two methods were compared for the preparation of MOX liposomes; the dehydration–rehydration (DRV) method and the active loading method (AL). Numerous lipid-membrane compositions were studied to determine the potential effect on MOX loading and retention in liposomes. MOX and phospholipid contents were measured by HPLC and a colorimetric assay for phospholipids, respectively. Vesicle size distribution and surface charge were measured by DLS, and morphology was evaluated by cryo-TEM. The AL method conferred liposomes with higher MOX encapsulation compared to the DRV method for all the lipid compositions used. Cryo-TEM showed that both liposome types had round vesicular structure and size around 100–150 nm, while a granular texture was evident in the entrapped aqueous compartments of most AL liposomes, but substantially less in DRV liposomes; X-ray diffraction analysis demonstrated slight crystallinity in AL liposomes, especially the ones with highest MOX encapsulation. AL liposomes retained MOX for significantly longer time periods compared to DRVs. Lipid composition did not affect MOX release from DRV liposomes but significantly altered drug loading/release in AL liposomes. Interestingly, AL liposomes demonstrated substantially higher antimicrobial potential towards S. epidermidis growth and biofilm susceptibility compared to corresponding DRV liposomes, indicating the importance of MOX retention in liposomes on their activity. In conclusion, the liposome preparation method/type determines the rate of MOX release from liposomes and modulates their antimicrobial potential, a finding that deserves further in vitro and in vivo exploitation

Inkjet printing of transdermal microneedles for the delivery of anticancer agents

A novel inkjet printing technology is introduced as a process to coat metal microneedle arrays with three anticancer agents 5-fluororacil, curcumin and cisplatin for transdermal delivery. The hydrophilic graft copolymer Soluplus® was used as a drug carrier and the coating formulations consisted of drug–polymer solutions at various ratios. A piezoelectric dispenser jetted microdroplets on the microneedle surface to develop uniform, accurate and reproducible coating layers without any material losses. Inkjet printing was found to depend on the nozzle size, the applied voltage (mV) and the duration of the pulse (μs). The drug release rates were determined in vitro using Franz type diffusion cells with dermatomed porcine skin. The drug release rates depended on the drug–polymer ratio, the drug lipophilicity and the skin thickness. All drugs presented increased release profiles (750 μm skin thickness), which were retarded for 900 μm skin thickness. Soluplus assisted the drug release especially for the water insoluble curcumin and cisplatin due to its solubilizing capacity. Inkjet printing was proved an effective technology for coating of metal microneedles which can then be used for further transdermal drug delivery applications

FORMATION OF CALCIUM SULFATE IN AQUENEOUS SOLUTIONS

IN THIS THESIS, WE STUDY THE PRECIPITATION OF CALCIUM SULFATE FROM AQUEOUS SOLUTIONS AT SUPERSATURATIONS SUFFICIENT FOR SPONTANEOUS PRECIPITATION AND IN THE TEMPERATURE RANGE BETWEEN 20 -80 C. AT THESE CONDITIONS, THE ONLY PHASE FORMING WAS CALCIUM SULFATE DIHYDRATE. THE INDUCTION PERIODS AND THE SUBSEQUENT RATES OF PRECIPITATION WERE FOUND TO STRONGLY DEPEND ON THE SOLUTION SUPERSATURATION AND TEMPERATURE. DECREASE OF SUPERSATURATION RESULTED IN CHANGE OF THE CRYSTAL GROWTH-MECHANISM FROM SURFACE NUCLEATION TO A STEP DISLOCATION MECHANISM. THE PRESENCE OF ORGANOPHOSPHORUS COMPOUNDS HEDP, ENTMP AND NTMP) EVEN AT VERY LOW CONCENTRATIONS (A FEW PPM) DECREASED THE RATES OF CALCIUM SULFATE DIHYDRATE PRECIPITATION IN THE ORDER (ENTMP>NTMP>>HEDP) AT CONDITIONS OF SUSTAINED SUPERSATURATION. MOREOVER, WE HAVE STUDIED THE INFLUENCE OF DIVALENT METAL-IONS (CD, MG, ZNAND SR) AT SUSTAINED SUPERSATURATION. THE EFFECT OF THESE METAL-IONS WAS LIMITED IN THE DECREASE OF SOLUTION SUPERSATURATION. FINALLY, THE PRESENCE OF CRYSTALS OF CALCIUM SULFATE DIHYDRATE FAVOURED THE FORMATION OF CALCIUM CARBONATE POLYMORPHS AT HIGH TEMPERATURES.ΣΤΗΝ ΠΑΡΟΥΣΑ ΕΡΓΑΣΙΑ ΜΕΛΕΤΗΘΗΚΕ Ο ΣΧΗΜΑΤΙΣΜΟΣ ΤΟΥ ΘΕΙΙΚΟΥ ΑΣΒΕΣΤΙΟΥ ΣΕ ΣΥΝΘΗΚΕΣΠΟΥ ΕΥΝΝΟΕΙΤΑΙ Η ΑΥΘΟΡΜΗΤΗ ΚΑΤΑΒΥΘΙΣΗ ΤΟΥ ΚΑΙ ΣΤΗΝ ΠΕΡΙΟΧΗ ΘΕΡΜΟΚΡΑΣΙΩΝ 20-80 C. ΣΤΙΣ ΣΥΝΘΗΚΕΣ ΑΥΤΕΣ ΒΡΕΘΗΚΕ ΟΤΙ ΚΑΤΑΒΥΘΙΖΕΤΑΙ ΑΠΟΚΛΕΙΣΤΙΚΑ ΔΙΕΝΥΔΡΟ ΘΕΙΙΚΟ ΑΣΒΕΣΤΙΟ. Ο ΜΗΧΑΝΙΣΜΟΣ ΚΑΤΑΒΥΘΙΣΗΣ ΕΞΑΡΤΑΤΑΙ ΑΜΕΣΑ ΑΠΟ ΤΟΝ ΥΠΕΡΚΟΡΕΣΜΟ ΤΟΥ ΔΙΑΛΥΜΑΤΟΣ ΕΡΓΑΣΙΑΣ. ΣΕ ΥΨΗΛΟΥΣ ΥΠΕΡΚΟΡΕΣΜΟΥΣ ΟΙ ΚΡΥΣΤΑΛΛΟΙ ΑΝΑΠΤΥΣΣΟΝΤΑΙ ΜΕ ΜΗΧΑΝΙΣΜΟ ΕΠΙΦΑΝΕΙΑΚΗΣ ΠΥΡΗΝΟΠΟΙΗΣΗΣ, ΕΝΩ ΣΕ ΧΑΜΗΛΟΥΣ ΥΠΕΡΚΟΡΕΣΜΟΥΣ ΑΝΑΠΤΥΣΣΟΝΤΑΙ ΜΕ ΜΗΧΑΝΙΣΜΟ ΕΛΙΚΟΕΙΔΟΥΣ ΜΕΤΑΤΟΠΙΣΗΣ ΒΗΜΑΤΟΣ. Η ΠΑΡΟΥΣΙΑ ΟΡΓΑΝΟΦΩΣΦΟΡΙΚΩΝ ΕΝΩΣΕΩΝ (HEDP, ENTMP KAI NTMP) ΜΕΙΩΝΕΙ ΤΗΝ ΤΑΣΗ ΣΧΗΜΑΤΙΣΜΟΥ ΤΟΥ ΔΙΕΝΥΔΡΟΥ ΘΕΙΙΚΟΥ ΑΣΒΕΣΤΙΟΥ ΜΕ ΤΗΝ ΑΚΟΛΟΥΘΗ ΣΕΙΡΑ (ΕΝΤΜΡ>ΝΤΜΠ>>HEDP) ΣΕ ΣΥΓΚΕΝΤΡΩΣΕΙΣ ΤΗΣ ΤΑΞΗΣ ΜΕΡΙΚΩΝΡΡΜ. Η ΠΑΡΟΥΣΙΑ ΔΙΣΘΕΝΩΝ ΜΕΤΑΛΛΟΙΟΝΤΩΝ (CD, ZN, MG ΚΑΙ SR) ΕΠΗΡΕΑΖΕΙ ΤΗΝ ΚΑΤΑΒΥΘΙΣΗ ΤΟΥ ΘΕΙΙΚΟΥ ΑΣΒΕΣΤΙΟΥ ΛΟΓΩ ΜΕΙΩΣΗΣ ΤΟΥ ΥΠΕΡΚΟΡΕΣΜΟΥ ΤΟΥ ΔΙΑΛΥΜΑΤΟΣ ΕΡΓΑΣΙΑΣ. ΕΠΙΣΗΣ ΒΡΕΘΗΚΕ ΟΤΙ Η ΠΑΡΟΥΣΙΑ ΔΙΕΝΥΔΡΟΥ ΘΕΙΙΚΟΥ ΑΣΒΕΣΤΙΟΥ ΕΥΝΝΟΕΙ ΤΟΝ ΣΧΗΜΑΤΙΣΜΟ ΑΝΘΡΑΚΙΚΟΥ ΑΣΒΕΣΤΙΟΥ ΣΕ ΥΨΗΛΕΣ ΘΕΡΜΟΚΡΑΣΙΕΣ

Arsenic trioxide liposomes: Encapsulation efficiency and in vitro stability

The use of arsenic-containing compounds in cancer therapy is currently being reconsidered, after the recent approval of arsenic trioxide (Trisenox(R)) for the treatment of relapsed promyelocytic leukemia (PML). In an attempt to prepare a carrier system to minimize the toxicity of this drug, the aim of this study is to prepare and characterize liposomes encapsulating arsenic trioxide (ATO). For this, we prepared different types of liposomes entrapping ATO: large multilamellar (MLV), sonicated (SUV) and dried reconstituted vesicles (DRV). The techniques used were: thin film hydration, sonication and the DRV method, respectively. Two lipid compositions were studied for each liposome type, EggPC/Chol (1: 1) and DSPC/Chol (1: 1). After liposome preparation, drug encapsulation was evaluated, by measuring arsenic in liposomes. For this, energy-dispersive X-ray fluorescence spectroscopy or atomic absorption was used. In addition, the retention of the drug in the liposomes was evaluated after incubating the liposomes in buffer at 37degreesC. The experimental results reveal that encapsulation of ATO in liposomes ranges between 0.003 and 0.506 mol/ mol of lipid, and is highest in the DRV vesicles and lowest in the small unilamellar vesicles, as anticipated. Considering the in vitro stability of ATO-encapsulating liposomes: 1) For the PC/Chol liposomes (DRV and MLV), after 24 hours of incubation, more than 70% (or 90% in some cases) of the initially encapsulated amount of ATO was released. 2) The liposomes composed of DSPC/Chol could retain substantially higher amounts of ATO, especially the DRV liposomes (54% retained after 24 h). 3) In the case of PC/Chol, temperature of incubation has no effect on the ATO release after 24 hours, but affects the rate of ATO release in the MLV liposomes, while for the DSPC/Chol liposomes there is a slight increase (statistically insignificant) of ATO release at higher temperature

Preparation of Benzothiazolyl-Decorated Nanoliposomes

Amyloid β (Aβ) species are considered as potential targets for the development of diagnostics/therapeutics towards Alzheimer’s disease (AD). Nanoliposomes which are decorated with molecules having high affinity for Aβ species may be considered as potential carriers for AD theragnostics. Herein, benzothiazolyl (BTH) decorated nanoliposomes were prepared for the first time, after synthesis of a lipidic BTH derivative (lipid-BTH). The synthetic pathway included acylation of bis(2-aminophenyl) disulfide with palmitic acid or palmitoyl chloride and subsequent reduction of the oxidized dithiol derivative. The liberated thiols were able to cyclize to the corresponding benzothiazolyl derivatives only after acidification of the reaction mixture. Each step of the procedure was monitored by HPLC analysis in order to identify all the important parameters for the formation of the BTH-group. Finally, the optimal methodology was identified, and was applied for the synthesis of the lipid-BTH derivative. BTH-decorated nanoliposomes were then prepared and characterized for physicochemical properties (size distribution, surface charge, physical stability, and membrane integrity during incubation in presence of buffer and plasma proteins). Pegylated BTH-nanoliposomes were demonstrated to have high integrity in the presence of proteins (in comparison to non-peglated ones) justifying their further exploitation as potential theragnostic systems for AD

Development and Comparative In Vitro and In Vivo Study of BNN27 Mucoadhesive Liposomes and Nanoemulsions for Nose-to-Brain Delivery

Intranasal administration offers an alternative and promising approach for direct nose-to-brain delivery. Herein, we developed two chitosan (CHT)-coated (and uncoated) nanoformulations of BNN27 (a synthetic C-17-spiro-dehydroepiandrosterone analogue), liposomes (LIPs), and nanoemulsions (NEs), and compared their properties and brain disposition (in vitro and in vivo). LIPs were formulated by thin film hydration and coated with CHT by dropwise addition. BNN27-loaded NEs (BNEs) were developed by spontaneous emulsification and optimized for stability and mucoadhesive properties. Mucoadhesive properties were evaluated by mucin adherence. Negatively charged CHT-coated LIPs (with 0.1% CHT/lipid) demonstrated the highest coating efficiency and mucoadhesion. BNEs containing 10% w/w Capmul-MCM and 0.3% w/w CHT demonstrated the optimal properties. Transport of LIP or NE-associated rhodamine-lipid across the blood–brain barrier (in vitro) was significantly higher for NEs compared to LIPs, and the CHT coating demonstrated a negative effect on transport. However, the CHT-coated BNEs demonstrated higher and faster in vivo brain disposition following intranasal administration compared to CHT-LIPs. For both BNEs and LIPs, CHT-coating resulted in the increased (in vivo) brain disposition of BNN27. Current results prove that CHT-coated NEs consisting of compatible nasal administration ingredients succeeded in to delivering more BNN27 to the brain (and faster) compared to the CHT-coated LIPs

Development and Comparative In Vitro and In Vivo Study of BNN27 Mucoadhesive Liposomes and Nanoemulsions for Nose-to-Brain Delivery

Intranasal administration offers an alternative and promising approach for direct nose-to-brain delivery. Herein, we developed two chitosan (CHT)-coated (and uncoated) nanoformulations of BNN27 (a synthetic C-17-spiro-dehydroepiandrosterone analogue), liposomes (LIPs), and nanoemulsions (NEs), and compared their properties and brain disposition (in vitro and in vivo). LIPs were formulated by thin film hydration and coated with CHT by dropwise addition. BNN27-loaded NEs (BNEs) were developed by spontaneous emulsification and optimized for stability and mucoadhesive properties. Mucoadhesive properties were evaluated by mucin adherence. Negatively charged CHT-coated LIPs (with 0.1% CHT/lipid) demonstrated the highest coating efficiency and mucoadhesion. BNEs containing 10% w/w Capmul-MCM and 0.3% w/w CHT demonstrated the optimal properties. Transport of LIP or NE-associated rhodamine-lipid across the blood–brain barrier (in vitro) was significantly higher for NEs compared to LIPs, and the CHT coating demonstrated a negative effect on transport. However, the CHT-coated BNEs demonstrated higher and faster in vivo brain disposition following intranasal administration compared to CHT-LIPs. For both BNEs and LIPs, CHT-coating resulted in the increased (in vivo) brain disposition of BNN27. Current results prove that CHT-coated NEs consisting of compatible nasal administration ingredients succeeded in to delivering more BNN27 to the brain (and faster) compared to the CHT-coated LIPs