Yan-Yan Xu

Selection of high efficient transdermal lipid vesicle for curcumin skin delivery

Curcumin shows effective anti-inflammatory activities but is seldom used in clinic because of its poor solubility in water and vulnerablity to sunshine ultraviolet effect. Novel lipid vesicles have been developed as carriers for skin delivery. In this paper, lipid vesicles-propylene glycol liposomes (PGL), Ethosomes and traditional liposomes, were prepared as curcumin carriers respectively. Their morphology, particle size and encapsulation efficiency and drug release behavior in vitro were evaluated. Transdermal efficiency and deposition quantity in abdominal skin were also measured with Franz diffusion device. Carrageenan-induced paw edema was established to evaluate the anti-inflammatory effect. From the result, the particle size order of lipid vesicles was: PGL (182.4 ± 89.2 nm)<Ethosomes (289 ± 132.1 nm)<traditional liposomes (632.9 ± 184.1 nm). The order of particle dispersion coefficient was as the same as that of particle size. The sequence of encapsulation efficiency was: PGL>Ethosomes>traditional liposomes. PGL had the best encapsulation efficiency of 92.74 ± 3.44%. From anti-inflammatory experiment, PGL showed the highest and longest inhibition on the development of paw edema, followed by Ethosomes and Traditional liposomes. With the elevated entrapment efficiency, good transdermic ability and sustained-release behavior, PGL may represent an efficient transdermal lipid vesicle for skin delivery.

Enhancing chemotherapeutic drug inhibition on tumor growth by ultrasound: an in vivo experiment

An in vivo study on enhancing epirubicin hydrochloride (EPI) inhibition on tumor growth by ultrasound (US) was reported. Five-week-old male nude mice were used and HL-60 cells were s.c. (subcutaneous injection) inoculated in axilla of these mice. Six groups were designed and five consecutive treatments were applied to investigate the inhibition on tumor growth and body weight growth. US applied locally to the tumor resulted in a substantially increased drug uptake in tumor cells. The inhibition on tumor growth depended on the position of drug injection and phospholipid-based microbubble (PMB) application. Tumor growth rate under group 1 (PMB+US) was similar to that of blank control. The order of the inhibition on tumor volume growth was: group 4 (s.c. EPI+PMB+US) > group 5 intraperitoneal (i.p. EPI+PMB+US) > group 2 (i.p. EPI) > group 3 (s.c. EPI+US) > group 1 (PMB+US). Similar conclusion was obtained from experimental measurements of tumor weight change. The order of animal survival status for EPI administration groups was: group 4 > group 5 > group 2 > group 3. Chemotherapeutic drug inhibition on tumor growth could be enhanced by local US combined with PMB, which might provide a potential application for US-mediated chemotherapy.

Synthesis and characterization of Poloxamer 188-grafted heparin copolymer

Background: Poloxamer 188 is a safe biocompatible polymer that can be used in protein drug delivery system. Aim: In this study, a new heparin–poloxamer 188 conjugate (HP) was synthesized and its physicochemical properties were investigated. HP structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and Hydrogen-1 nuclear magnetic resonance spectroscopy (1H-NMR). Content of the conjugated heparin was analyzed using Toluidine Blue. The critical micelle concentration (CMC) of the copolymer was determined by a fluorescence probe technique. The effect of HP on the gelation of poloxamer 188 was characterized by the rheological properties of the HP–poloxamer hydrogels. Solubility and viscosity of HP were also evaluated compared with poloxamer 188. Results: From the results, the solubility of the conjugated heparin was increased compared with free heparin. The content of heparin in HP copolymer was 62.9%. The CMC of HP and poloxamer 188 were 0.483 and 0.743 mg/mL, respectively. The gelation temperature of 0.4 g/mL HP was 43.5°C, whereas that of the same concentration of poloxamer 188 was 37.3°C. With HP content in poloxamer 188 solution increasing, a V-shape change of gelation temperature was observed. Conclusion: Considering the importance of poloxamer 188 in functional material, HP may prove to be a facile temperature-sensitive material for protein drug-targeted therapy.

Experiment on the factors for enhancing the susceptibility of cancer cells to chemotherapeutic drug by ultrasound microbubbles.

The objective of this study was to investigate the factors for enhancing the susceptibility of cancer cells to chemotherapeutic drug by ultrasound microbubbles. Ultrasound (US) combined with phospholipid-based microbubbles (MB) was used to enhance the susceptibility of colon cancer cell line SWD-620 to anticancer drugs Topotecan hydrochloride (TOP). Experiments were designed to investigate the influence of main factors on cell viability and cell inhibition, such as US intensity, MB concentration, drug combination with MB, asynchronous action between US triggered cavitation and drug entering cell, MB particle size. US exposure for 10 sec with US probe power at 0.6 W/cm2 had satisfied cell viability. Treated with US combined with 15% MB, cell viability maintained more than 85% and cell inhibition 86.16%. Under optimal US combined with MB, TOP showed much higher cell inhibition than that of only TOP group. Cell inhibition under short delayed time (<2 h) for TOP addition did not show obvious difference. In terms of MB particle size, the order of cell inhibition was: Mixture > Micron bubble part > Nanometer bubble part. US combined with MB can enhance the susceptibility of cancer cells to chemotherapeutic drug, which may provide a potential method for US-mediated tumor chemotherapy.

Comparing encapsulation efficiency and ultrasound-triggered release for protein between phospholipid-based microbubbles and liposomes

This work was to compare the encapsulation efficiency and ultrasound-triggered release for protein between microbubbles and liposomes. Bovine serum albumin (BSA) was used as a model. Final ratios between BSA and HPC in microbubbles and liposomes were 1:5, 1:7 and 1:10, respectively. Morphologic characteristics and contrast enhancement of loaded microbubbles and liposomes were measured. Encapsulation efficiency and ultrasound-stimulated release profile were detected. The mean size of loaded microbubbles and liposomes was 3.4 microm and 1.7 microm, respectively. Encapsulation efficiency of microbubbles had an inverse relationship with the ratio between BSA and HPC, while loaded liposomes remained nearly unchanged in the designed range of the ratio between BSA and HPC. Microbubbles resulted in significant enhancement of CnTi images. After ultrasound, more than 90% of the entrapped BSA was released from microbubbles, but less than 5% of BSA released from liposomes. Microbubbles are a promising delivery system for proteins.

Experiment on formulation and drug release behavior of porosity asymmetric membrane capsules in vitro

Porosity asymmetric membrane capsules were prepared to study the relationship between the capsule formulation and drug release. Cellulose acetate (CA) and pore formers were used in the capsule shell formulation as the main semipermeable membrane material. The capsules were permeable to both water and dissolved solutes. Using sparingly soluble drug acetaminophen as a model, cumulative release was calculated. The slope of the release profile from the distilled water had good relationship with the concentration of the pore formers F68. The release of acetaminophen was independent to the pH, osmotic pressure of dissolution medium, but influenced by intensity of agitation. When the concentration of pore former was low, zero-order release behavior was observed within 24 h which was consistent with Fickian diffusion model. When the concentration of pore former was high, however, Higuchi model release was found which is caused by Fickian diffusion and osmotic pressure release. With scanning electron microscope (SEM), the surface structure and cross-section of the capsule shell were also studied before and after drug delivery. With simple preparation and broad scope of drug application, porosity asymmetric membrane capsules can give desired drug extended release and show more convenience than controlled tablets with laser drilling.

Comparing the Enhancement Efficiency Between Liposomes and Microbubbles for Insulin Pulmonary Absorption

BACKGROUND The present study investigated the enhancement efficiency between liposomes and microbubbles for insulin pulmonary absorption. METHODS Two types of phospholipid-based vesicle-liposomes and microbubbles-were prepared, and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cytotoxicity test was used to evaluate their in vitro toxicity in A549 cells. Cellular uptake of insulin combined with liposomes or microbubbles was determined using A549 cells. With intratracheal insufflation of Sprague-Dawley rats, an insulin mixture with liposomes or microbubbles was administered to assess its potential for promoting drug pulmonary absorption. RESULTS Both liposomes and microbubbles had a narrow and monodispersed size distribution with average diameter of 3.1 μm and 1.0 μm, respectively. From the MTT cytotoxicity test, a phospholipid-based vesicle concentration of <25% (vol/vol) in the final volume was the safe dosage range that could avoid severe cytotoxic effects. The intracellular uptake amount of insulin in the insulin-microbubble mixture was significantly higher than that in the insulin-liposome mixture. The minimum reductions of the blood glucose concentration produced by insulin-microbubble and insulin-liposome mixtures were 60.8% and 35.0% of the initial glucose levels, respectively, and their bioavailabilities relative to subcutaneous injection were 48.6% and 30.8%, respectively. CONCLUSIONS Microbubbles have much better efficiency than liposomes in the rate and extent of insulin pulmonary absorption. Microbubbles might be recommended as a potential agent for enhancing protein intrapulmonary absorption.

Preparation and microscopy examination of alginate-poly-l-lysine-alginate microcapsules

Abstract Ca-alginate-poly-l-lysine-alginate (APA-Ca) and Ba-alginate-poly-l-lysine-alginate (APA-Ba) microcapsules were prepared and their thickness and surface were examined by light microscopy and scanning electron microscopy. Specifically, light microscopy with frozen section was used to visualize and quantify the thickness of APA membrane, and monitor temporal changes in the thickness of microcapsules during a month long culture in vitro. The section graph of APA microcapsule represents the accurate measurement of layer thickness of APA-Ca with diameter 900 ± 100 and 500 ± 100 μm at 6.01 ± 1.02 and 9.54 ± 2.42 μm (p < 0.05), and layer thickness of APA-Ba with diameter 900 ± 100 and 500 ± 100 μm at 5.47 ± 0.90 and 8.21 ± 1.97 μm (p < 0.05), regardless of the alginate composition used to generate the microcapsules. The microcapsule was stable during the culture for 30 days in vitro. Field emission scanning electron microscopy with freeze drying method was used to detect the surface and thickness of dried microcapsules. From the results, the outer surface of APA-Ca and APA-Ba membrane were smooth and dense, the film thickness of the APA-Ca was about 450–690 nm, while the APA-Ba was approximately 335 nm. In vivo experiment, little significant difference was seen in the change of film thickness of microcapsules in intrapertioneal site for 30 days after transplantation (p > 0.05), except that the recovery of APA-Ba was higher than the APA-Ca microcapsules. The paper showed an easy method to prepare APA-Ca and APA-Ba, and examine their thickness and surface, which could be utilized to study other types of microcapsules.

An In Vivo Experiment to Improve Pulmonary Absorption of Insulin Using Microbubbles

BACKGROUND Gas-filled phospholipid-based ultrasonic microbubbles (PUMs) are widely used in diagnostic imaging. The micro- or nanoparticle size and the physiochemical nature of shell provide the potential for a new way to improve pulmonary absorption for peptides and proteins. METHODS Male Sprague-Dawley rats were fasted for 12 h. Then insulin solution and insulin-PUM mixture solution were administered by intratracheal instillation. The hypoglycemic effect was observed to evaluate insulin absorption after lung administration. Fluorescein isothiocyanate-dextran (molecular mass, 4 kDa) was used as the index of evaluating drug alveolar deposition and absorption by visualization techniques. RESULTS Administration of insulin solution containing PUMs significantly reduced the blood glucose levels of Sprague-Dawley rats, compared with administration of insulin-only solution. The minimum reductions of the blood glucose concentration produced by insulin solution containing PUMs and by an insulin-only solution reached 60.81% and 34.60% of the initial glucose levels, respectively, and their bioavailabilities relative to subcutaneous injection were 48.58% and 29.09%, respectively. Histopathological study of the lung showed no changes in the morphology of the pulmonary alveoli after administration to these drugs. Only a slight inflammatory cell infiltration in the alveoli could be found in some rats. CONCLUSION These results suggested that PUMs might be used as an effective way to improve pulmonary absorption for peptides and proteins.