Preparation and characterization of polymeric pH-sensitive STEALTH® nanoparticles for tumor delivery of a lipophilic prodrug of paclitaxel

Paclitaxel is an effective and widely used anti-cancer agent. However, the drug is difficult to formulate for parenteral administration because of its low water solubility and Cremophor EL, the expient used for its formulation, has been shown to cause serious side effects. The present study reports an alternative administration vehicle involving a lipophilic paclitaxel prodrug, paclitaxel oleate, incorporated in the core of a nanoparticle-based dosage form. A hydrophobic poly (β-amino ester) (PbAE) was used to formulate the nanoparticles, which were stabilized with a mixture of phosphatidylcholine, Synperonic? F 108, and poly(ethylene glycol)-dipalmitoyl phosphatidyl ethanolamine. PbAE undergoes rapid dissolution when the pH of the medium is less than 6.5 and is expected to rapidly release its content within the acidic tumor microenvironment and endo/lysosome compartments of cancer cells. PbAE nanoparticles were prepared by an ultrasonication method and characterized for particle size and physical stability. The nanoparticles obtained had a diameter of about 70 nm and a good physical stability when stored at 4 °C. In vitro cellular uptake and release of paclitaxel oleate PbAE nanoparticles were studied in Jurkat acute lymphoblastic leukemia cells. The results were compared with pclitaxel oleate in poly(?-caprolactone) (PCL) particles, that do not display pH-sensitive release behavior, and paclitaxel in PbAE particles. Both uptake and release of the prodrug were faster when administered in PbAE than in PCL, but much slower than those of the free drug in PbAE. Cytotoxicity assay was performed on the formulations at different doses. Paclitaxel and paclitaxel oleate showed almost identical activity, IC50 123 and 128 nM, respectively, while that of the prodrug in PCL was much lower with IC50 at 2.5 μM. Thus, PbAE nanoparticles with the incorporated paclitaxel prodrug paclitaxel oleate may prove useful for replacement of the toxic Cremophor EL and also by improving the distribution of the drug to the tumor.     

Construction and application of biotin–poloxamer conjugate micelles for chemotherapeutics

Biotin was conjugated on poloxamer to prepare biotin–poloxamer (BP) conjugate micelles for chemotherapeutics. Epirubicin (EPI) was encapsulated in BP micelles. The EPI-loaded BP micelles were characterized in terms of size, ζ-potential, morphology, drug loading, drug encapsulation and drug release. Marrow leukemic HL-60 cells were used for evaluating the in vitro cytotoxicity of EPI-loaded BP micelles. Nude mice were axillainoculated subcutaneously HL-60 cells to establish tumour model for investigating the inhibition effects of EPI-loaded BP micelles. From the results, the sizes of these nanoparticles were about 100?nm. Fluorescence microscope observation supported the enhanced cellular uptake of the micelles. The order of the inhibition on tumour volume growth was: EPI-loaded BP micelles >EPI-loaded MATP micelles >EPI-loaded poloxamer micelles >EPI. BP micelles showed significant antitumour activity and low toxicity, compared with the non-targeted micelles. With the advantage of EPR effect and tumour-targeting potential, BP conjugate micelles might be developed as a new system for chemotherapeutics.     

Novel oral dosage regimen based on self-nanoemulsifying drug delivery systems for codelivery of phytochemicals – Curcumin and thymoquinone

BackgroundCurcumin and Thymoquinone are very well-known phytochemicals for their potent anti-inflammatory and anticancer properties. The major challenges for curcumin is its poor aqueous solubility and erratic oral bioavailability.ObjectiveTo develop a novel liquid self-nanoemulsifying drug delivery system (SNEDDS) containing curcumin and thymoquinone and further converted into a solid dosage form using adsorbents Syloid® and Neusilin® as the solid carrier.MethodsThe characterization of the liquid and solid SNEDDS was performed by particle size & zeta potential analysis, scanning electron microscopy, differential scanning calorimetry, fourier transform infrared spectroscopy and X-ray powder diffraction. The drug loading, and in vitro release studies were carried out to investigate the efficiency of curcumin release from SNEDDS.ResultsThe liquid SNEDDS containing black seed oil showed excellent self-emulsification performance with transparent appearance. The results of characterization studies showed that solidification using 50% (w/w) Syloid® and Neusilin® in the liquid formulation yield free flowing powder with no agglomeration but Neusilin® produced smooth granules than Syloid® and kept the drugs stable in amorphous state. In vitro dissolution studies indicated that liquid SNEDDS formulations of F4 and its solid SNEDDS using Neusilin® provided high dissolution efficiency and reproducibility for curcumin and thymoquinone. However, Neusilin® showed higher rate of dissolution (more than 65%, p < 0.05) compared to Syloid® for curcumin.ConclusionsCurcumin loaded-SNEDDS formulation containing thymoquinone in liquid & solid dosage forms were successfully developed with an increased drug loading and dissolution rate, which could be the potential combined delivery system for various anti-inflammatory and anti-cancer treatments.     

Novel vaginal delivery systems for calcitonin: II. Preparation and characterization of HYAFF® microspheres containing calcitonin

Microspheres prepared from hyaluronan esters (HYAFF®) have been evaluated as a novel delivery system for the vaginal administration of salmon calcitonin (sCT). HYAFF® microspheres containing sCT were prepared by a solvent extraction method. Spherical microspheres of about 10 mm in diameter with smooth surfaces were obtained. An HPLC method was developed for the determination of sCT incorporated into the microspheres. The efficiency of incorporation was high, with approximately 80 to 90% of the peptide recovered by extraction from the microspheres. Quantification of the extracted peptide in vivo confirmed that the biological activity of sCT was unaffected by the microsphere preparation process.     

Novel co-axial prilling technique for the development of core–shell particles as delayed drug delivery systems

In this study, biocompatible double layered beads consisting of pectin core and alginate shell were prepared through a single step manufacturing process based on prilling apparatus equipped with co-axial nozzles. The core was loaded with piroxicam (PRX) as model non-steroidal anti-inflammatory drug (NSAID). Morphology, size distribution and shape of the double layered beads varied depending on the operative conditions and polymer concentrations. Co-axial nozzles size, applied vibration frequency, gelling conditions and, mainly, polymers mass ratio were identified as critical variables. Particularly, the relative viscosity of polymeric feed solutions inside the nozzle was the key parameter to obtain homogeneous and well-formed coated particles. The produced beads were investigated for the release kinetic in different media. Once PRX was encapsulated within the pectin core, a controlled release pattern was observed. Particularly, beads produced with 4:1 core/shell ratio (F4) released less than 30% of PRX in simulated gastric fluid (SGF) while total liberation of the drug was achieved during the next 3 h in simulated intestinal fluid (SIF). More interesting, F4 tested in SIF was able to release drug in a delayed and sustained manner at established time points (2h_8.2%, 3h_32.2%, 4h_70.1% and 5h_about 100%). Based on the above results, co-axial prilling approach is expected to provide success in manufacturing systems with delayed drug release profiles. Such systems may be potentially useful in targeting diseases which are affected by the circadian rhythm, such as chronic inflammation.     

Preparation and in vitro–in vivo evaluation of surface-modified poly(lactide-co-glycolide) nanoparticles as controlled release carriers for flutamide delivery

Abstract

This investigation explores the use of methoxy polyethylene glycol (mPEG) functionalised poly(d,l-lactide-co-glycolide) (PLGA) nanocrystals of flutamide (FLT) with enhanced solubility, bioavailability and blood circulation time for targeting prostate cancer. FLT had Log P 3.27, short half life 5–6?h, low water solubility, permeability and bioavailability with extensive first-pass metabolism. FLT-loaded nanocrystals were prepared using nanoprecipitation method with surface coating by mPEG and characterised through differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electronic microscopy, particle size, zeta potential, percent entrapment efficiency (% EE), in vitro dissolution, haemolysis, sterility, bioavailability and stability studies. The percent cumulative drug release and % EE of optimised formulation was found to be 95.21?±?1.18 and 88.36?±?1.20, respectively, for 48?h. In addition, FLT-loaded PEGylated PLGA nanocrystals exhibited significantly delayed blood clearance with drug level of about 766.71?ng/mL at 48?h. In conclusion, PEGylated PLGA FLT nanocrystals could be demonstrated as a novel approach to enhance solubility, bioavailability and blood circulation time.     

Preparation and evaluation of PLGA microparticles as carrier for the pulmonary delivery of rhIL-2 : I. Effects of some formulation parameters on microparticle characteristics

In this study, recombinant human interleukin-2 (rhIL-2) containing poly(lactic-co-glycolic acid) (PLGA) microparticles were prepared for pulmonary administration by modified w/o/w double emulsion solvent extraction method and the effects of various formulation parameters on the physicochemical properties of the microparticles were investigated. Microparticles in suitable size for pulmonary administration (4.02?µm) were obtained by increasing dichloromethane volume used in the organic phase. Also, a very high encapsulation efficiency (99.22%) value could be reached in these microparticles. In the sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis, rhIL-2 extracted from microparticles having a similar band with native rhIL-2 showed that the protein was not affected by the encapsulation process. The release curves of microparticles exhibited a biphasic fashion, characterized by a fast release phase at initial 1 day, followed by a slower one on the remaining days. Bioactivity investigations using T cells show that rhIL-2 encapsulated in PLGA microparticles retain their biological activity.     

Preparation and evaluation of PLGA microparticles as carrier for the pulmonary delivery of rhIL-2 : I. Effects of some formulation parameters on microparticle characteristics

In this study, recombinant human interleukin-2 (rhIL-2) containing poly(lactic-co-glycolic acid) (PLGA) microparticles were prepared for pulmonary administration by modified w/o/w double emulsion solvent extraction method and the effects of various formulation parameters on the physicochemical properties of the microparticles were investigated. Microparticles in suitable size for pulmonary administration (4.02?μm) were obtained by increasing dichloromethane volume used in the organic phase. Also, a very high encapsulation efficiency (99.22%) value could be reached in these microparticles. In the sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis, rhIL-2 extracted from microparticles having a similar band with native rhIL-2 showed that the protein was not affected by the encapsulation process. The release curves of microparticles exhibited a biphasic fashion, characterized by a fast release phase at initial 1 day, followed by a slower one on the remaining days. Bioactivity investigations using T cells show that rhIL-2 encapsulated in PLGA microparticles retain their biological activity.     

Preparation and characterization of HA–PEG–PCL intelligent core–corona nanoparticles for delivery of doxorubicin

The objective of the present study was to synthesize core–corona nanoparticles of doxorubicin (DOX) using hyaluronic acid–polyethyleneglycol–polycaprolactone (HA–PEG–PCL) copolymer for tumor targeting. Targeting efficiency of HA–PEG–PCL nanoparticles was compared with non-HA-containing nanoparticles (methoxy poly ethylene glycol (MPEG)–PCL). The copolymers were chemically synthesized and characterized by IR and NMR spectroscopies. The nanoparticles were characterized for shape and morphology by transmission electron microscopy, particle size, percentage of drug entrapment, and in vitro drug release profile. Differential scanning calorimetry and X-ray diffraction studies were also performed to appraise the crystalline or amorphous nature of DOX inside the polymer matrix. Formulations were prepared using different DOX:polymer ratios (1:1–1:3 w/w) and the optimum formulation with the drug:polymer ratio of 1:1 showed the mean particle size of 95 ± 5 nm and entrapment efficiency of 95.56% in the case of HA–PEG–PCL nanoparticles, while the values were 115 nm and 95.50%, respectively, in the case of MPEG–PCL nanoparticles. The HA–PEG–PCL nanoparticles could release DOX for up to 17 days, whereas the MPEG–PCL nanoparticles could release it for up to 14 days. The hemolytic toxicity and hematological studies confirmed that both DOX-loaded HA–PEG–PCL and MPEG–PCL nanoparticles were safe and suitable for sustained and targeted drug delivery. The tissue distribution study and tumor growth inhibition were performed after intravenous injection of nanoparticles in Ehrlich ascites tumor (EAT)-bearing mice. The nanoparticles of HA–PEG–PCL copolymer accomplishes efficient delivery of DOX in EAT tumor when compared with the MPEG–PCL nanoparticles by the process of receptor-mediated endocytosis, as well as enhanced permeability and retention effect.     

Binding and uptake of novel RGD micelles to the αvβ3 integrin receptor for targeted drug delivery

Abstract

Purpose: To understand the binding and internalization of novel RGD micelles in tumor cells that overexpress the α_vβ₃ integrin receptor.

Methods: Peptide amphiphiles containing a C16 or C18 fatty-acid chain with one or two ADA units linked to an RGD motif were prepared, characterized, and assessed for their binding specificity to the α_vβ₃ receptor. The internalization of the amphiphiles was evaluated by confocal microscopy and cytotoxicity studies in A2058 cells that overexpress the α_vβ₃ integrin receptor.

Results: The CMC and size and of RGD micelles ranged from 9 to 30?μM and 130 to 300?nm, respectively. Micelles showed good in vitro stability by retaining their micellar integrity and good specificity by binding to the α_vβ₃ integrin receptor in an RGD-dependent manner. Confocal studies showed higher intracellular fluorescence when FITC was delivered through the micelles compared with its free form and showed significantly higher FITC uptake at 37?°C versus 4?°C (p?<?0.05). The lower IC50 values were obtained when paclitaxel was delivered to A2058 cells via the RGD-loaded carriers (3.6–4.87?nM) compared with unencapsulated drug (7.86?nM), further demonstrated micelle specificity to the α_vβ₃ receptor.

Conclusion: RGD micelles bound specifically to the α_vβ₃ receptor and their uptake was mediated by an endocytic process.     

β-Lactoglobulin tablets as a suitable vehicle for protection and intestinal delivery of probiotic bacteria

The use of succinylated β-lactoglobulin as a novel functional tablet excipient for the protection of probiotic bacteria against the adverse gastric conditions and their delivery in the intestine was studied. Tablets were produced by direct compression of a dry mixture of Bifidobacterium longum HA-135 and the tested excipient. The results showed that tablets made of native β-lg did not ensure cell survival while grafting carboxylic acid groups on the protein revealed to be an innovative method to create a gastroresistant matrix that could allow the survival of up to 10(8)CFU and 10(7)CFU after 1h and 2h gastric incubation, respectively. When compared to other polymers, succinylated β-lg promoted the best survival both upon compression and after simulated gastric passage. The proportion of succinylated β-lg in the formulation could be lowered to 60% without modifying the protective ability of the matrix. Additionally, the tablets proved to be stable over a period of 3 months when refrigerated. Succinylated β-lg tablets are an interesting vehicle for the protection of acid-sensitive bacteria during transit in the upper gastro-intestinal tract.     

α-Tocopherol succinate-modified chitosan as a micellar delivery system for paclitaxel: preparation, characterization and in vitro/in vivo evaluations

α-Tocopherol succinate hydrophobically modified chitosan (CS-TOS) containing 17 α-tocopherol groups per 100 anhydroglucose units was synthesized by coupling reaction. The formation of CS-TOS was confirmed by ¹H NMR and FT-IR analysis. In aqueous medium, the polymer could self-aggregate to form micelles, and the critical micelle concentration (CMC) was determined to be 5.8 × 10⁻³ mg/ml. Transmission electron microscopy (TEM) observation revealed that both bare and paclitaxel-loaded micelles were near spherical in shape. The mean particle size and zeta potential of drug-loaded micelles were about 78 nm and +25.7 mV, respectively. The results of DSC and XRD analysis indicated that paclitaxel was entrapped in the micelles in molecular or amorphous state. In vitro cytotoxicity and hemolysis study revealed the effectiveness and safety of this delivery system, which was further confirmed by the in vivo antitumor evaluations. It can be concluded that the CS-TOS was a potential micellar carrier for paclitaxel.     

Solid lipid nanoparticles for transdermal delivery of diclofenac sodium: preparation, characterization and in vitro studies

The aim of this study was to prepare diclofenac sodium (DNa) solid lipid nanoparticles (SLNs) by a modified emulsion/solvent evaporation method for transdermal delivery. Five independent processing parameters including the lipid matrix, emulsifiers, co-emulsifiers, water-dispersed phase and organic phase were assessed systematically to enhance the entrapment of DNa. The SLNs produced by optimal formulation were submicrometre size with low polydispersity index, the entrapment efficiency was about 89% and the drug loading was about 9.5%. Shape and surface morphology were determined by transmission electron microscopy, which revealed the fairly spherical and core-shell shapes of the SLNs. The in?vitro release of SLNs showed a two-step release pattern: one initial burst release followed by a second slow-release phase. In the in?vitro cutaneous permeation studies, value of flux obtained for DNa solution was higher than that of SLNs suspension. SLNs had also been shown to improve the dermal localization of DNa.     

Preparation and evaluation of injectable Rasagiline mesylate dual-controlled drug delivery system for the treatment of Parkinson’s disease

A microsphere–gel in situ forming implant (MS–Gel ISFI) dual-controlled drug delivery system was applied to a high water-soluble small-molecule compound Rasagiline mesylate (RM) for effective treatment of Parkinson’s disease. This injectable complex depot system combined an in situ phase transition gel with high drug-loading and encapsulation efficiency RM–MS prepared by a modified emulsion-phase separation method and optimized by Box–Behnken design. It was evaluated for in vitro drug release, in vivo pharmacokinetics, and in vivo pharmacodynamics. We found that the RM-MS-Gel ISFI system showed no initial burst release and had a long period of in vitro drug release (60?days). An in vivo pharmacokinetic study indicated a significant reduction (p?in situ gel systems after intramuscular injection to rats. A pharmacodynamic study demonstrated a significant reduction (p?p?in situ phase transition gel is superior for use as a biodegradable and injectable sustained drug delivery system with a low initial burst and long period of drug release for highly hydrophilic small molecule drugs.     

The Diels–Alder reaction: A powerful tool for the design of drug delivery systems and biomaterials

Click reactions have the potential to greatly facilitate the development of drug delivery systems and biomaterials. These reactions proceed under mild conditions, give high yields, and form only inoffensive by-products. The Diels–Alder cycloaddition is one of the click reactions that do not require any metal catalyst; it is one of the most useful reactions in synthetic organic chemistry and material design. Herein, we highlight possible applications of the Diels–Alder reaction in pharmaceutics and biomedical engineering. Particular focus is placed on the synthesis of polymers and dendrimers for drug delivery, the preparation of functionalized surfaces, bioconjugation techniques, and applications of the Diels–Alder reaction in nanotechnology. Moreover, applications of the reaction for the preparation of hydrogels for drug delivery and tissue engineering are reviewed. A general introduction to the Diels–Alder reaction is presented, along with a discussion of potential pitfalls and challenges. At the end of the article, we provide a set of tools that may facilitate the application of the Diels–Alder reaction to solve important pharmaceutical or biomedical problems.     

Preparation and in vitro evaluation of anti-VCAM-1-Fab'-conjugated liposomes for the targeted delivery of the poorly water-soluble drug celecoxib

When an inflammatory stimulus is given, vascular endothelial cells express various cell adhesion molecules including the vascular cell adhesion molecule (VCAM)-1. In this study, the possibility of specifically delivering anti-inflammatory drugs to activated endothelial cells by utilizing VCAM-1 as a target receptor was explored by loading celecoxib, a selective cyclooxygenase-2 inhibitor, into liposomes coupled to the Fab' fragment against VCAM-1. Anti-VCAM-1-Fab'-conjugated liposomes were prepared by forming an amide linkage between amino groups of Fab' and the carboxylic group of glutaryl-N-phosphatidylethanolamine in liposomes using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a cross-linker in the presence of sulpho-N-hydroxysuccinimide. The coupling of Fab' to phospholipids constituting liposomes was confirmed by SDS-PAGE analysis. Under our optimized conjugation conditions, 130.0?μg Fab' was coupled to 1?μmol liposomes. Immunoblotting analysis showed that VCAM-1 protein expression could be induced by incubating human umbilical vein endothelial cells (HUVEC) with TNF-α. Confocal laser microsopy analysis revealed that Fab' conjugation to liposomes selectively increased liposomal uptake in TNF-α-pre-stimulated (VCAM-1-expressed) HUVECs, but not in cells without VCAM-1 expression. The concentration of celecoxib loaded in Fab'-conjugated liposomes was 281.1?±?29?μg/mL, suggesting that liposomal loading also helped to overcome the limitations in celecoxib administration caused by its poor water solubility. Celecoxib loaded in Fab'-conjugated liposomes inhibited prostaglandin E? (PGE?) production induced by TNF-α-pre-stimulation more efficiently than when loaded in conventional liposomes. Therefore, Fab'-conjugated liposomes served as a drug delivery system with dual functions: targeted delivery and solubilizing capacity.     

Preparation and evaluation of luteolin–phospholipid complex as an effective drug delivery tool against GalN/LPS induced liver damage

Context: The phyto-phospholipid complexation technique is a promising approach to improve the bioavailability and efficacy of flavonoids.

Objective: The objective of this study was to improve the bioavailability and efficacy of luteolin by phospholipid complexation against inflammatory liver damage.

Materials and methods: The phospholipid complex of luteolin (LPC) was prepared by solvent evaporation accompanied by freeze drying. The physicochemical properties of LPC were investigated by means of spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Pharmacokinetic parameters in rats were determined and the hepatoprotective potential was assessed against d-galctosamine and lipopolysaccharide (GalN/LPS) induced hepatic damage.

Results: LPC showed drug loading of 74.14% and average particle size 147.4?nm. The results of FTIR, thermal and diffraction studies confirmed the formation of complex. The aqueous/n-octanol solubility showed improvements. LPC showed an increase in relative in vivo bioavailability to 535.31% of pure luteolin. The histological and biochemical changes induced by GalN/LPS were significantly ameliorated by LPC.

Discussion: Hepatoprotective effect of LPC was more profound than luteolin with a particle size suitable for passive targeting of inflammatory sites.

Conclusion: LPC was successfully formulated under optimized conditions and is an efficient drug delivery system for oral administration of luteolin with enhanced bioavailability and hepatoprotective potential.     

Thermosensitive PEG–PCL–PEG (PECE) hydrogel as an in situ gelling system for ocular drug delivery of diclofenac sodium

Development of efficient ocular drug delivery systems was still a challenging task. The objective of this article was to develop a thermosensitive PEG–PCL–PEG (PECE) hydrogel and investigate its potential application for ocular drug delivery of diclofenac sodium (DIC). PECE block polymers were synthesized by coupling MPEG-PCL co-polymer using IPDI reagent, and then its sol–gel transition as a function with temperature was investigated by a rheometer. The results showed that 30% (w/v) PECE aqueous solution exhibited sol–gel transition at approximately 35?°C. In vitro release profiles showed the entrapped DIC was sustained release from PECE hydrogels up to 7 days and the initial drug loading greatly effect on release behavior of DIC from PECE hydrogels. MTT assay results indicated that no matter PECE or 0.1% (w/v) DIC-loaded PECE hydrogels were nontoxic to HCEC and L929 cells after 24?h culturing. In vivo eye irritation test showed that the instillation of either 30% (w/v) PECE hydrogels or 0.1% (w/v) DIC-loaded PECE hydrogels to rabbit eye did not result in eye irritation within 72?h. In vivo results showed that the AUC_0–48?h of 0.1% (w/v) DIC-loaded PECE hydrogels exhibited 1.6-fold increment as compared with that of commercial 0.1% (w/v) DIC eye drops, suggesting the better ophthalmic bioavailability could be obtained by the instillation of 0.1% (w/v) DIC-loaded PECE hydrogels.     

β-Casein nanoparticle-based oral drug delivery system for potential treatment of gastric carcinoma: Stability, target-activated release and cytotoxicity

We studied a potential drug delivery system comprising the hydrophobic anticancer drug paclitaxel entrapped within β-casein (β-CN) nanoparticles and its cytotoxicity to human gastric carcinoma cells. Paclitaxel was entrapped by stirring its dimethyl sulfoxide (DMSO) solution into PBS containing β-CN. Cryo-TEM analysis revealed drug nanocrystals, the growth of which was blocked by β-CN. Entrapment efficiency was nearly 100%, and the nanovehicles formed were colloidally stable. Following encapsulation and simulated digestion with pepsin (2 hours at pH = 2, 37 °C), paclitaxel retained its cytotoxic activity to human N-87 gastric cancer cells; the IC₅₀ value (32.5 ± 6.2 nM) was similar to that of non-encapsulated paclitaxel (25.4 ± 2.6 nM). Without prior simulated gastric digestion, β-CN-paclitaxel nanoparticles were non-cytotoxic, suggesting the lack of untoward toxicity to bucal and esophageal epithelia. We conclude that β-CN shows promise to be useful for target-activated oral delivery of hydrophobic chemotherapeutics in the treatment of gastric carcinoma, one of the leading causes of cancer mortality worldwide.     

Preparation and in vitro evaluation of anti-VCAM-1-Fab′-conjugated liposomes for the targeted delivery of the poorly water-soluble drug celecoxib

When an inflammatory stimulus is given, vascular endothelial cells express various cell adhesion molecules including the vascular cell adhesion molecule (VCAM)-1. In this study, the possibility of specifically delivering anti-inflammatory drugs to activated endothelial cells by utilizing VCAM-1 as a target receptor was explored by loading celecoxib, a selective cyclooxygenase-2 inhibitor, into liposomes coupled to the Fab′ fragment against VCAM-1. Anti-VCAM-1-Fab′-conjugated liposomes were prepared by forming an amide linkage between amino groups of Fab′ and the carboxylic group of glutaryl-N-phosphatidylethanolamine in liposomes using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a cross-linker in the presence of sulpho-N-hydroxysuccinimide. The coupling of Fab′ to phospholipids constituting liposomes was confirmed by SDS-PAGE analysis. Under our optimized conjugation conditions, 130.0?µg Fab′ was coupled to 1?µmol liposomes. Immunoblotting analysis showed that VCAM-1 protein expression could be induced by incubating human umbilical vein endothelial cells (HUVEC) with TNF-α. Confocal laser microsopy analysis revealed that Fab′ conjugation to liposomes selectively increased liposomal uptake in TNF-α-pre-stimulated (VCAM-1-expressed) HUVECs, but not in cells without VCAM-1 expression. The concentration of celecoxib loaded in Fab′-conjugated liposomes was 281.1?±?29?µg/mL, suggesting that liposomal loading also helped to overcome the limitations in celecoxib administration caused by its poor water solubility. Celecoxib loaded in Fab′-conjugated liposomes inhibited prostaglandin E₂ (PGE₂) production induced by TNF-α-pre-stimulation more efficiently than when loaded in conventional liposomes. Therefore, Fab′-conjugated liposomes served as a drug delivery system with dual functions: targeted delivery and solubilizing capacity.