Hongjie Mu

Preparation and characterization of puerarin–dendrimer complexes as an ocular drug delivery system

Objective: The aim of this study was to prepare and characterize the complex of puerarin and poly(amidoamine) (PAMAM) dendrimers and to evaluate the complex as an ocular drug delivery system. Methods: The complexes of puerarin and PAMAM dendrimers were prepared at various puerarin-to-dendrimer ratios. The physicochemical properties of the complexes were characterized by differential scanning calorimetry and Fourier transform infrared spectroscopy. The in vitro release studies were performed by dialysis. Corneal permeation was evaluated by Valia-Chien diffusion cell with excised corneas and ocular residence time in rabbits. Results: The results showed that puerarin-dendrimer complexes formed primarily by hydrogen-bonding interactions. Typically, 43, 56, 125, and 170 molecules of puerarin could be incorporated into G3.5, G4, G4.5, and G5 PAMAM dendrimer molecule. Puerarin was released more slowly from puerarin-dendrimer complexes than free puerarin in deionized water and phosphate buffer solution (pH 6.8). The in vitro release rate of puerarin complexed with full generation dendrimers was lower than that with half generation dendrimers. Furthermore, puerarin-dendrimer complexes produced longer ocular residence times in rabbits compared with puerarin eye drops. No damages to the epithelium or endothelium were observed after the PAMAM dendrimer administration in this corneal permeation study. Conclusions: Puerarin-dendrimer complexes represent a potential ocular drug delivery system to improve the efficacy of drug treatment.

Effects of a novel pH-sensitive liposome with cleavable esterase-catalyzed and pH-responsive double smart mPEG lipid derivative on ABC phenomenon

Background The ABC phenomenon is described as a syndrome of accelerated clearance of polyethylene glycol (PEG)-modified liposomes from the bloodstream when repeatedly injected, with their increased accumulation in the liver and spleen. Methods To clarify this immune response phenomenon, we evaluated a novel modified pH-sensitive liposome with a cleavable double smart PEG-lipid derivative (mPEG-Hz-CHEMS). Results The ABC phenomenon in mice was brought about by repeated injection of conventional PEG-PE liposomes and was accompanied by a greatly increased uptake in the liver. However, a slight ABC phenomenon was brought about by repeated injection of mPEG-CHEMS liposomes and was accompanied by only a slightly increased uptake in the liver, and repeated injection of mPEG-Hz-CHEMS liposomes did not induce the ABC phenomenon and there was no increase in liver accumulation. This finding indicates that the cleavable mPEG-Hz-CHEMS derivative could lessen or eliminate the ABC phenomenon induced by repeated injection of PEGylated liposomes. Conclusion This research has shed some light on a solution to the ABC phenomenon using a cleavable PEG-Hz-CHEMS derivative encapsulated in nanoparticles.

pH and temperature dual-sensitive liposome gel based on novel cleavable mPEG-Hz-CHEMS polymeric vaginal delivery system

Background In this study, a pH and temperature dual-sensitive liposome gel based on a novel cleavable hydrazone-based pH-sensitive methoxy polyethylene glycol 2000-hydrazone-cholesteryl hemisuccinate (mPEG-Hz-CHEMS) polymer was used for vaginal administration. Methods The pH-sensitive, cleavable mPEG-Hz-CHEMS was designed as a modified pH-sensitive liposome that would selectively degrade under locally acidic vaginal conditions. The novel pH-sensitive liposome was engineered to form a thermogel at body temperature and to degrade in an acidic environment. Results A dual-sensitive liposome gel with a high encapsulation efficiency of arctigenin was formed and improved the solubility of arctigenin characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. The dual-sensitive liposome gel with a sol-gel transition at body temperature was degraded in a pH-dependent manner, and was stable for a long period of time at neutral and basic pH, but cleavable under acidic conditions (pH 5.0). Arctigenin encapsulated in a dual-sensitive liposome gel was more stable and less toxic than arctigenin loaded into pH-sensitive liposomes. In vitro drug release results indicated that dual-sensitive liposome gels showed constant release of arctigenin over 3 days, but showed sustained release of arctigenin in buffers at pH 7.4 and pH 9.0. Conclusion This research has shed some light on a pH and temperature dual-sensitive liposome gel using a cleavable mPEG-Hz-CHEMS polymer for vaginal delivery.

Intranasal delivery of rotigotine to the brain with lactoferrin-modified PEG-PLGA nanoparticles for Parkinson’s disease treatment

Sustainable and safe delivery of brain-targeted drugs is highly important for successful therapy in Parkinson’s disease (PD). This study was designed to formulate biodegradable poly(ethylene glycol)–poly(lactic-co-glycolic acid) (PEG-PLGA) nanoparticles (NPs), which were surface-modified with lactoferrin (Lf), for efficient intranasal delivery of rotigotine to the brain for the treatment of PD. Rotigotine NPs were prepared by nanoprecipitation, and the effect of various independent process variables on the resulting properties of NPs was investigated by a Box–Behnken experimental design. The physicochemical and pharmaceutical properties of the NPs and Lf-NPs were characterized, and the release kinetics suggested that both NPs and Lf-NPs provided continuous, slow release of rotigotine for 48 h. Neither rotigotine NPs nor Lf-NPs reduced the viability of 16HBE and SH-SY5Y cells; in contrast, free rotigotine was cytotoxic. Qualitative and quantitative cellular uptake studies demonstrated that accumulation of Lf-NPs was greater than that of NPs in 16HBE and SH-SY5Y cells. Following intranasal administration, brain delivery of rotigotine was much more effective with Lf-NPs than with NPs. The brain distribution of rotigotine was heterogeneous, with a higher concentration in the striatum, the primary region affected in PD. This strongly suggested that Lf-NPs enable the targeted delivery of rotigotine for the treatment of PD. Taken together, these results demonstrated that Lf-NPs have potential as a carrier for nose-to-brain delivery of rotigotine for the treatment of PD.

Magnetically and pH dual responsive dendrosomes for tumor accumulation enhanced folate-targeted hybrid drug delivery.

Dendrosomes are new tumor targeted drug delivery systems to improve safety and therapeutic effects of antitumor agents. In this study we designed and synthesized magnetically and pH dual responsive dendrosomes with magnetic nanoparticles and folate-targeted dendrimers encapsulated in long-circulating pH sensitive liposomes. Cellular uptake and tissue penetration were assessed on cell lines and tumor spheroids respectively. Xenograft mice were used to study tumor accumulation. The dendrosomes were stable at pH7.4, but responsively released their content at acidic pH. In slightly acid environments, the hybrid vectors showed similar cytotoxicity and cellular uptake to the free folate-dendrimers conjugate due to rapid release. The dendrosomes showed a greater cellular uptake by HeLa cells (FA receptor positive) due to the conjugation with folic acid (FA). In multicellular tumor spheroid tests, a slightly acidic environment and the application of magnet both promoted the permeation efficiency of the hybrid vectors. In the xenograft mice model both in vivo images and tissue distribution assessment indicated that the dendrosomes had higher peak intensity and a longer residence time. Through the synergistic effects of magnetic responsiveness and both passive and active targeting properties, the multi-functional dendrosomes were demonstrated to have great potential as a promising anticancer drug delivery platform.

Determination of puerarin in rabbit aqueous humor by liquid chromatography tandem mass spectrometry using microdialysis sampling after topical administration of puerarin PAMAM dendrimer complex.

To study pharmacokinetic properties of puerarin poly(amido amine) (PAMAM) dendrimer complex, a sensitive liquid chromatography tandem mass spectrometry method (LC-MS/MS) was developed and validated to determine puerarin in rabbit aqueous humor using microdialysis sampling. Astilbin was used as the internal standard. The linear range for puerarin was from 2 to 1000ng/mL (r=0.9986) based on 20μL of aqueous humor. The coefficients of variations for intra-day and inter-day precisions were less than 10.0%, and the relative error of accuracy was within ±6.3%. The mean extraction recovery of puerarin varied from 80.4% to 85.5%. Microdialysis provides a complete concentration versus time profile. A significant difference was observed in main pharmacokinetic parameters of C(max), AUC and t(1/2) between puerarin solution and puerarin PAMAM dendrimer complex. Complex formation resulted in an obvious increase in bioavailability of puerarin after topical administration to rabbit according to the above LC-MS/MS assay method.

Synthesis of a bi-functional dendrimer-based nanovehicle co-modified with RGDyC and TAT peptides for neovascular targeting and penetration

The dual-ligand dendritic polyamidoamine-(polyethylene glycol)n-cyclic RGDyC peptide-(TAT peptide) (PPnR(T)) with various supplied molar ratios of polyethylene glycol (PEG) to polyamidoamine (PAMAM) (n=5, 15, 30) were designed as drug-carriers for the treatment of neovascular diseases; their targeting and penetrating effects were subsequently evaluated. (1)H NMR demonstrated PPnR(T) was successfully synthesized. Compared with the unmodified PAMAM, in vitro cytotoxicity of PPnR(T) to αvβ3 negative cells (αvβ3-) was significantly reduced, whereas the lethality to pathologic neovascular endothelial cells (αvβ3+) was efficiently increased compared to PPn. Compared to PP5R(T) and PP15R(T), PP30R(T) exhibited the most selective and efficient cellular uptake by human umbilical vein endothelial cells (HUVECs, αvβ3+). Membrane interaction study indicated the cellular uptake process of PP30R(T) of HUVECs mainly involved specific RGD-αvβ3 recognition as well as electrostatic interactions. Intracellular localization results confirmed PP30R(T) was distributed in the cytoplasm in HUVECs. 3D tumor spheroids penetration studies demonstrated that PP30R(T) penetrated the A549 cells to reach the depths of the avascular tumor spheroids. In vivo imaging further demonstrated that PP30R(T) achieved profoundly improved distribution in tumor tissues where angiogenesis existed. Therefore, the bi-functional dendrimer PP30R(T) displayed great potential as a nano-carrier for targeted drug delivery both in vitro and in vivo, and had broad prospects as nanocarriers for the targeted treatment of neovascular diseases.

lower irritation microemulsion-based rotigotine gel: formulation optimization and in vitro and in vivo studies

Background Rotigotine is a potent and selective D1, D2, and D3 dopaminergic receptor agonist. Due to an extensive first-pass effect, it has a very low oral bioavailability (approximately 0.5% in rats). Purpose The present investigation aimed to develop a microemulsion-based hydrogel for transdermal rotigotine delivery with lower application site reactions. Methods Pseudoternary phase diagrams were constructed to determine the region of oil in water (o/w)-type microemulsion. Central composite design was used to support the pseudoternary phase diagrams and to select homogeneous and stable microemulsions with an optimal amount of rotigotine permeation within 24 hours. In vitro skin permeation experiments were performed, using Franz diffusion cells, to compare rotigotine-loaded microemulsions with rotigotine solutions in oil. The optimized formulation was used to prepare a microemulsion-based hydrogel, which was subjected to bioavailability and skin irritancy studies. Results The selected formulations of rotigotine-loaded microemulsions had enhanced flux and permeation coefficients compared with rotigotine in oil. The optimum microemulsion contained 68% water, 6.8% Labrafil®, 13.44% Cremophor® RH40, 6.72% Labrasol®, and 5.04% Transcutol® HP; the drug-loading rate was 2%. To form a microemulsion gel, 1% Carbomer 1342 was added to the microemulsion. The bioavailability of the rotigotine-loaded microemulsion gel was 105.76%±20.52% with respect to the marketed rotigotine patch (Neupro®). The microemulsion gel irritated the skin less than Neupro. Conclusion A rotigotine microemulsion-based hydrogel was successfully developed, and an optimal formulation for drug delivery was identified. This product could improve patient compliance and have broad marketability.

Topical ocular delivery to laser-induced choroidal neovascularization by dual internalizing RGD and TAT peptide-modified nanoparticles

A nanoparticle (NP) was developed to target choroidal neovascularization (CNV) via topical ocular administration. The NPs were prepared through conjugation of internalizing arginine-glycine-aspartic acid RGD (iRGD; Ac-CCRGDKGPDC) and transactivated transcription (TAT) (RKKRRQRRRC) peptide to polymerized ethylene glycol and lactic-co-glycolic acid. The iRGD sequence can specifically bind with integrin αvβ3, while TAT facilitates penetration through the ocular barrier. 1H nuclear magnetic resonance and high-performance liquid chromatography demonstrated that up to 80% of iRGD and TAT were conjugated to poly(ethylene glycol)– poly(lactic-co-glycolic acid). The resulting particle size was 67.0±1.7 nm, and the zeta potential of the particles was −6.63±0.43 mV. The corneal permeation of iRGD and TAT NPs increased by 5.50- and 4.56-fold compared to that of bare and iRGD-modified NPs, respectively. Cellular uptake showed that the red fluorescence intensity of iRGD and TAT NPs was highest among primary NPs and iRGD- or TAT-modified NPs. CNV was fully formed 14 days after photocoagulation in Brown Norway (BN) rats as shown by optical coherence tomography and fundus fluorescein angiography analyses. Choroidal flat mounts in BN rats showed that the red fluorescence intensity of NPs followed the order of iRGD and TAT NPs > TAT-modified NPs > iRGD-modified NPs > primary NPs. iRGD and TAT dual-modified NPs thus displayed significant targeting and penetration ability both in vitro and in vivo, indicating that it is a promising drug delivery system for managing CNV via topical ocular administration.

Novel multicore niosomes based on double pH-sensitive mixed micelles for Ginsenoside Rh2 delivery

Abstract In this study, we report the novel double pH-sensitive mixed micelles to fabricate multicore niosomes for drug delivery. The double pH-sensitive mixed micelles (PMM) were prepared with different pH-sensitive polymers, mPEG2000-Hz-CHEMS and mPEG2000-IS (2:1 w/w). Ginsenoside Rh2-loaded DPMM was mixed with Pluronic F-68, in the aqueous medium, and multicore niosomes were fabricated. The size of multicore niosomes were around 100–300 nm with a high encapsulation efficiency of G-Rh2. The G-Rh2-MCN could release encapsulated G-Rh2 with an accelerated rate under lower pH conditions with lower cytotoxicity and good antitumor efficacy.