Wang et al. Nanoscale Research Letters (2017) 12:66 DOI 10.1186/s11671-017-1826-1 NANO EXPRESS Open Access Effect of Paclitaxel-Mesoporous Silica Nanoparticles with a Core-Shell Structure on the Human Lung Cancer Cell Line A549 Tieliang Wang1, Ying Liu2 and Chao Wu2* Abstract A nanodrug delivery system of paclitaxel-mesoporous silica nanoparticles with a core-shell structure (PAC-csMSN) was used to increase the dissolution of paclitaxel (PAC) and improve its treatment of lung cancer. PAC was loaded into the core-shell mesoporous silica nanoparticles (csMSN) by the adsorption equilibrium method and was in an amorphous state in terms of its mesoporous structure. In vitro and in vivo studies showed that csMSN increased the dissolution rate of PAC and improved its lung absorption. The area under concentration-time curve (AUC) value of PAC-csMSN used for pulmonary delivery in rabbits was 2.678-fold higher than that obtained with the PAC. After continuous administration for 3 days, a lung biopsy showed no signs of inflammation. Cell apoptosis results obtained by flow cytometry indicated that PAC-csMSN was more potent than pure PAC in promoting cell apoptosis. An absorption investigation of PAC-csMSN in A549 cells was carried out by transmission electron microscopy (TEM) and laser scanning confocal microscopy (LSCM). The obtained results indicated that the cellular uptake was time-dependent and csMSN was uptaken into the cytoplasm. All these results demonstrate that csMSN have the potential to achieve pulmonary inhalation administration of poorly water-soluble drugs for the treatment of lung cancer. Keywords: Mesoporous silica nanoparticles, Paclitaxel, A549 cells, Dissolution, Pulmonary delivery Background to improve the solubility of PAC has become an import- Most anticancer drugs are water-insoluble, and the poor ant challenge. Currently, some methods are available for solubility seriously restricts their absorption. Classical improving PAC solubility, such as the use of micelles, treatment for lung cancer involves oral or intravenous liposomes, and nanoparticles [7–9]. With the develop- administration of antifungal drug formulations [1–3]. ment of nanotechnology, the application of mesoporous However, these compounds have many side effects and materials for improving the solubility of poorly water- are not very effective [4]. For these common routes of soluble drugs is attracting wide attention. Zongzhe zhao administration, a stable and efficient lung drug concen- et al. have reported the development of mesoporous tration is not always guaranteed due to low solubility silica materials in improving the solubility of fenofibrate and/or poor tissue penetration, which may also lead to a and regulating its release rate [10]. Peng zhao et al. apply poor survival prognosis. Pulmonary delivery is an inter- mesoporous carbon materials to increase the dissolution esting choice because it delivers anticancer drugs rate of poorly water-soluble drugs [11]. Porous hydroxy- directly to the cancerous tissue while maintaining high apatite, porous alumina, and porous titanium dioxide lung drug concentrations and reducing systemic side materials have also been used to improve the water solu- effects [5, 6]. bility of insoluble drugs [12–14]. PAC, an effective anticancer drug, is poorly water- In our research, we have developed a csMSN-based soluble (solubility in water is 6 ng/ml). Therefore, how PAC nanodrug delivery system for improving the treat- ment of lung cancer. There are two reasons for choosing * Correspondence: [email protected] csMSN as carrier for improving PAC solubility. Firstly, 2Pharmacy School, Jinzhou Medical University, 40 Songpo Road, Linghe District, the spatial confinement effect of the mesoporous struc- Jinzhou, Liaoning Province 121000, China ture can reduce the drug particle size and increase the Full list of author information is available at the end of the article © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Wang et al. Nanoscale Research Letters (2017) 12:66 Page 2 of 8 specific surface area of the drug particles. According to in a vacuum. The drug content was determined by high- the Noyes-Whitney and Ostwald-Freundlich equations, performance liquid chromatography (HPLC) (L-2400, this would increase the dissolution rate of PAC. HITACHI, Japan). The drug loading (DD) of csMSN was Secondly, csMSN has a regular shape, low density, calculated by the formula: and good flowability which make them suitable as a carrier for pulmonary delivery. In the work, we DD ¼ the amount of drug in PAC−csMSN= wished to investigate whether csMSN could be used the amount of PAC−csMSN: as a pulmonary delivery carrier using a lung absorp- tion study at a cellular level. Characterization of csMSN and PAC-csMSN Methods The structure and morphology of csMSN was observed Materials by transmission electron microscopy (TEM; Tecnai PAC was provided by the Dalian Meilun Company with a G2F30) and scanning electron microscopy (SEM; JEOL purity >99%. Acetonitrile, anhydrous ethanol, butylpara- JSM-7001F). The adsorption analyzer (SA3100, Beckman ben, Tween 80, tetraethylorthosilicate (TEOS), aminopro- Coulter Inc., Brea, CA, USA) was used to detect the spe- pyltriethoxysilane (APTES), glutaraldehyde, hypromellose, cific surface area and pore size of csMSN. The phase hexadecyl trimethyl ammonium bromide (CTAB), ammo- transition process of PAC in all samples was performed nia, methyl tert-butyl ether, and dichloromethane were using differential scanning calorimetry (DSC; Shimadzu obtained from the Jin Zhou Xing Bei reagent company. DSC-60, Japan) at a heating rate of 10 °C/min from 25 Fluorescein isothiocyanate (FITC), Hoechst 33342, to 350 °C under a nitrogen flow of 150 ml/min. X-ray rhodamine phalloidin and 3-(4,5-Dimethylthiazol-2-yl)- diffraction analysis (XRD; Rigaku Geigerflex XRD, Co., 2,5-diphenyltetrazolium (MTT) were purchased from Japan,) was used to further investigate the physical state Beijing Dingguo Changsheng Biotechnology Co., Ltd. of PAC in csMSN. The step length was 0.02° and the Deionized water was used in all experiments. scanning rate was 4°/min from 3° (2θ) to 60°. FTIR spec- tra were recorded for analyzing the interaction PAC and Synthesis of csMSN csMSN using an FT-IR spectrometer (Bruker IFS 55, − csMSN was prepared according to the process reported Switzerland) over 400 to 4000 cm 1 using the KBr pellet by Wu et al. [15]. Firstly, ethanol, deionized water, and technique. ammonia (180:65:4.5, v/v/v) were mixed in a glass con- tainer under stirring. Then, TEOS (15 ml) was slowly In Vitro Drug Dissolution dripped into the solution. The reaction was carried out Dissolution testing was performed using a USP dissol- for 4 h and then solid silica nanoparticles (SSN) were ution apparatus type II (RC-8D, Tianjin Guoming obtained by centrifugation at 9500 rpm for 200 min. The Medical Equipment Co., Ltd.). The dissolution medium product was then dried at 40 °C. Secondly, ethanol, de- was pH 7.4 phosphate buffer with 1% Tween 80. For ionized water, CTAB, and the dried SSN (13:30:150:100, this, 10 mg PAC and PAC-csMSN powder containing an v/v/m/m) were mixed in a glass container and stirred for equivalent of 10 mg PAC were respectively put in 30 min under ultrasonication. Ammonia (0.45 ml) and 1000 ml dissolution medium at a temperature of 37 ± TEOS (0.3 ml) were then added to the system and 0.5 °C and the paddle speed was 100 rpm/min. Then, stirred at room temperature for 6 h. The precipitate ob- 5 ml samples of dissolution medium were withdrawn at tained by centrifugation was washed repeatedly with 5, 10, 15, 20, 30, 45, and 60 min and passed through a ethanol and water, and then dried at 40 °C. csMSN was 0.22 μm microporous membrane filter for HPLC ana- obtained by calcination at 550 °C. lysis. The detection wavelength was 227 nm, and the mobile phase was acetonitrile and water with a volume Drug-Loading Procedure ratio of 50:50 [17]. PAC, an anticancer drug, is used clinically to treat ovar- ian cancer, breast cancer, lung cancer, and colorectal In Vivo Pharmacokinetic Study cancer. It was chosen as a model drug and was loaded Animals and Dosing onto csMSN by the adsorption equilibrium method [16]. The animal experiment was approved by the Jinzhou The drug loading of csMSN was concentration- Medical University Laboratory Animal Ethics Committee. dependent. The same amount of csMSN was soaked in Twelve rabbits (2.5 ± 0.5 kg) were randomly assigned to different concentrations of PAC dichloromethane solution two groups for evaluating the pharmacokinetics of PAC- and then the suspension was stirred for 5 h. The super- csMSN powder and PAC powder after pulmonary natant was removed by centrifugation at 10,000 rpm and, administration. After fasting for 12 h, one group was given finally, the drug-loaded sample (PAC-csMSN) was dried a suspension of PAC-csMSN powder containing 2% Wang et al. Nanoscale Research Letters (2017) 12:66 Page 3 of 8 hypromellose (equivalent to 10 mg PAC) while the other 40, 80, 160, and 320 μg/ml of PAC concentration. MTT group was given an aqueous suspension of PAC powder solution (20 μl/well) was added and incubated for 4 h. (10 mg) containing 2% hypromellose by the trachea Next, DMSO (200 μl) was added and the cytotoxicity cannula-instillation method [18, 19]. All rabbits had free was determined by a Plate Reader (DNM-9606) at access to drinking water throughout the study. Blood sam- 492 nm (Tecan, Germany) [20]. ples (3.0 ml) were collected from the ear vein at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 h and centrifuged at The Flow Cytometry Assays 5000 rpm for 10 min.