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1.
Zhou H  Yu W  Guo X  Liu X  Li N  Zhang Y  Ma X 《Biomacromolecules》2010,11(12):3480-3486
Novel amphiphilic chitosan derivatives (glycidol-chitosan-deoxycholic acid, G-CS-DCA) were synthesized by grafting hydrophobic moieties, deoxycholic acid (DCA), and hydrophilic moieties, glycidol, with the purpose of preparing carriers for poorly soluble drugs. Based on self-assembly, G-CS-DCA can form nanoparticles with size ranging from 160 to 210 nm, and G-CS-DCA nanoparticles maintained stable structure for about 3 months when stored in PBS (pH 7.4) at room temperature. The critical aggregation concentration decreased from 0.043 mg/mL to 0.013 mg/mL with the increase of degree of substitution (DS) of DCA. Doxorubicin (DOX) could be easily encapsulated into G-CS-DCA nanoparticles and keep a sustained release manner without burst release when exposed to PBS (pH 7.4) at 37 °C. Antitumor efficacy results showed that DOX-G-CS-DCA have significant antitumor activity when MCF-7 cells were incubated with different concentration of DOX-G-CS-DCA nanoparticles. The fluorescence imaging results indicated DOX-G-CS-DCA nanoparticles could easily be uptaken by MCF-7 cells. These results suggested that G-CS-DCA nanoparticles may be a promising carrier for DOX delivery in cancer therapy.  相似文献   

2.
In this investigation, new biodegradable brush-like amphiphilic copolymers were synthesized by ring opening polymerization. Poly(L-lactide) (PLLA) was grafted onto chondroitin sulfate (CS), which is one of the physiologically significant specific glycosaminoglycans (GAGs), using a tin octanoate [Sn(Oct)2] catalyst in DMSO. The hydroxyl groups of the chondroitin sulfate were used as initiating groups. These functional groups enable specific mucoadhesion or receptor recognition. The degree of substitution (DS), the degree of polymerization (DP) and the chondroitin sulfate content (from 1.1 to 15.4%) were analyzed by 1H NMR. The characteristics of these grafted copolymers, including the structure, the thermal properties and biodegradability, etc., were examined with respect to CS content. Meanwhile, the amphiphilic core (PLLA)-corona (CS) nanoparticles, with size smaller than 200 nm, was examined by dynamic light scattering (DLS). Zeta potential analysis exhibited the value in the range -18.3 to -49.4 mV. The morphologies of the nanoparticles were observed by field-emission scanning electron microscopy (FE-SEM). The nanoparticles with lower cytotoxicity were examined by MTT assay. Furthermore, the in vitro BSA release kinetics of those CSn-PLLA nanoparticles was also determined in this study.  相似文献   

3.
Dextran is widely exploited in medical products and as a component of drug-delivering nanoparticles (NPs). Here, we tested whether dextran can serve as the main substrate of NPs and form a stable backbone. We tested dextrans with several molecular masses under several synthesis conditions to optimize NP stability. The analysis of the obtained nanoparticles showed that dextran NPs that were synthesized from 70 kDa dextran with a 5% degree of oxidation of the polysaccharide chain and 50% substitution with dodecylamine formed a NP backbone composed of modified dextran subunits, the mean diameter of which in an aqueous environment was around 100 nm. Dextran NPs could be stored in a dry state and reassembled in water. Moreover, we found that different chemical moieties (e.g., drugs such as doxorubicin) can be attached to the dextran NPs via a pH-dependent bond that allows release of the drug with lowering pH. We conclude that dextran NPs are a promising nano drug carrier.  相似文献   

4.
H Kuang  S Wu  Z Xie  F Meng  X Jing  Y Huang 《Biomacromolecules》2012,13(9):3004-3012
Biodegradable nucleobase-grafted amphiphilic copolymer, the methoxyl poly (ethylene glycol)-b-poly (L-lactide-co-2-methyl-2(3-(2,3-dihydroxylpropylthio) propyloxycarbonyl)-propylene carbonate/1-carboxymethylthymine) (mPEG-b- P(LA-co-MPT)), was synthesized. (1)H NMR titration and FT-IR spectroscopy indicated that the hydrogen-bonding could be formed between mPEG-b-P(LA-co-MPT) and 9-hexadecyladenine (A-C16). The hydrophobic microenvironment of the amphiphilic copolymer can protect the complementary multiple hydrogen bonds between mPEG-b-P(LA-co-MPT) and A-C16 from water effectively. The addition of A-C16 not only lowered the critical aggregation concentration (CAC) of mPEG-b-P(LA-co-MPT)/A-C16 nanoparticles (NPs) in aqueous solution but also induced different morphologies, which can be observed by transmission electron microscopy (TEM). Meanwhile, dynamic light scattering (DLS) and turbidometry was utilized to evaluate the effect of temperature and pH change on the stability of mPEG-b-P(LA-co-MPT)/A-C16 NPs. Cytotoxicity evaluation showed good biocompatibility of the mPEG-b-P(LA-co-MPT)/A-C16 NPs. The in vitro drug release profile showed that with the increase of A-C16 content, the doxorubiucin (DOX) release at pH 7.4 decreased, while the faster release rate was observed with the addition of A-C16 with a pH of 5.0. Importantly, DOX-loaded NPs exerted comparable cytotoxicity against MDA-MB-231 cells. This work provided a new method to stabilize NP structure using hydrogen-bonds and would have the potential to be applied in controlled drug delivery.  相似文献   

5.
Yao Y  Zhao L  Yang J  Yang J 《Biomacromolecules》2012,13(6):1837-1844
This study is devoted to developing amphiphilic block polymers based on phenylborate ester, which can self-assemble to form nanoparticles, as a glucose-sensitive drug carrier. Poly(ethylene glycol)-block-poly[(2-phenylboronic esters-1,3-dioxane-5-ethyl) methylacrylate] (MPEG5000-block-PBDEMA) was fabricated with MPEG5000-Br as a macroinitiator via atom transfer radical polymerization (ATRP). Using the solvent evaporation method, these block polymers can disperse in aqueous milieu to self-assemble into micellar aggregates with a spherical core-shell structure. Zeta potential and fluorescence techniques analysis showed a good purification effect, high encapsulation efficiency, and loading capacity of fluorescein isothiocyanate (FITC)-insulin-loaded polymeric micelles under optimal conditions. The in vitro insulin release profiles revealed definite glucose-responsive behavior of the polymeric micelles at pH 7.4 and 37 °C, depending on the environmental glucose concentration and the chemical composition of the block polymers. Further, circular dichroism spectroscopy demonstrated that the overall tertiary structure of the released insulin was in great agreement with standard insulin. (1)H NMR results of the polymeric micelles during glucose-responsive process supposed one possible insulin release mechanism via the polymer polarity transition from amphiphilic to double hydrophilic. The analysis of L929 mouse fibroblast cells viability suggested that the polymeric micelles from MPEG5000-block-PPBDEMA had low cell toxicity. The block polymers containing phenylborate ester that responded to changes in the glucose concentration at neutral pH are being aimed for use in self-regulated insulin delivery.  相似文献   

6.
The amphiphilic molecule dextrin-VA-SC16 (dexC16) was synthesized and studied in this work. DexC16 has a hydrophilic dextrin backbone with grafted acrylate groups (VA) substituted with hydrophobic 1-hexadecanethiol (C16). A versatile synthetic method was developed allowing control of the dextrin degree of substitution with the hydrophobic chains (DSC16, number of alkyl chains per 100 dextrin glucopyranoside residues). Materials with different DSC16 were prepared and characterized using 1H NMR. DexC16 self-assembles in water through association of the hydrophobic alkyl chains, originating nanoparticles. The nanoparticles properties were studied by dynamic light scattering (DLS), fluorescence spectroscopy, and atomic force microscopy (AFM).  相似文献   

7.
Small interfering RNA (siRNA) is a promising new therapeutic modality that can specifically silence disease-related genes. The main challenge for successful clinical development of therapeutic siRNA is the lack of efficient delivery systems. In this study, we have designed and synthesized a small library of novel multifunctional siRNA carriers, polymerizable surfactants with pH-sensitive amphiphilicity based on the hypothesis that pH-sensitive amphiphilicity and environmentally sensitive siRNA release can result in efficient siRNA delivery. The polymerizable surfactants comprise a protonatable amino head group, two cysteine residues, and two lipophilic tails. The surfactants demonstrated pH-sensitive amphiphilic hemolytic activity or cell membrane disruption with rat red blood cells. Most of the surfactants resulted in low hemolysis at pH 7.4 and high hemolysis at reduced pH (6.5 and 5.4). The pH-sensitive cell membrane disruption can facilitate endosomal-lysosomal escape of siRNA delivery systems at the endosomal-lysosomal pH. The surfactants formed compact nanoparticles (160-260 nm) with siRNA at N/P ratios of 8 and 10 via charge complexation with the amino head group, lipophilic condensation, and autoxidative polymerization of dithiols. The siRNA complexes with the surfactants demonstrated low cytotoxicity. The cellular siRNA delivery efficiency and RNAi activity of the surfactants correlated well with their pH-sensitive amphiphilic cell membrane disruption. The surfactants mediated 40-88% silencing of luciferase expression with 100 nM siRNA and 35-75% with 20 nM siRNA in U87-luc cells. Some of the surfactants resulted in similar or higher gene silencing efficiency than TransFast. EHCO with no hemolytic activity at pH 7.4 and 6.5 and high hemolytic activity at pH 5.4 resulted in the best siRNA delivery efficiency. The polymerizable surfactants with pH-sensitive amphiphilicity are promising for efficient siRNA delivery.  相似文献   

8.
The aim of the present research was to evaluate the potential of galactosylated low molecular weight chitosan (Gal-LMWC) nanoparticles bearing positively charged anticancer, doxorubicin (DOX) for hepatocyte targeting. The chitosan from crab shell was depolymerized, and the lactobionic acid was coupled with LMWC using carbodiimide chemistry. The depolymerized and galactosylated polymers were characterized. Two types of Gal-LMWC(s) with variable degree of substitution were employed to prepare the nanoparticles using ionotropic gelation with pentasodium tripolyphosphate anions. Factors affecting nanoparticles formation were discussed. The nanoparticles were characterized by transmission electron microscopy and photon correlation spectroscopy and found to be spherical in the size range 106–320 nm. Relatively higher percent DOX entrapment was obtained for Gal-LMWC(s) nanoparticles than for LMWC nanoparticles. A further increase in drug entrapment was found with nanoparticles prepared by Gal-LMWC with higher degree of substitution. A hypothesis which correlates the ionic concentration of DOX in nanoparticles preparation medium and percent DOX entrapment in cationic polymer has been proposed to explain the enhanced DOX entrapment. In-vitro drug release study demonstrated an initial burst release followed by a sustained release. The targeting potential of the prepared nanoparticles was assessed by in vitro cytotoxicity study using the human hepatocellular carcinoma cell line (HepG2) expressing the ASGP receptors on their surfaces. The enthusiastic results showed the feasibility of Gal-LMWC(s) to entrap the cationic DOX and targeting potential of developed Gal-LMWC(s) nanoparticles to HepG2 cell line.  相似文献   

9.
用醇类从酵母菌中释放超氧化物歧化酶   总被引:4,自引:0,他引:4  
研究了一种用醇类有机溶剂处理法从酵母菌中选择性地释放超氧化物歧化酶(SOD)的方法。当采用异丙醇浓度为90%,浸泡120min,抽提缓冲液为50mmol/L磷酸盐缓冲液(Ph7.0)时,抽提20h,SOD释放的活力为300u/ml,杂蛋白释放量最少,SOD比活达300u/mg。SOD释放率可达90%,和传统的超声波法和机械法相比,而比活提高了25倍。这种方法不需要任何复要设备,操作简单,成本低廉,在释放SOD同时,可达到初步纯化SOD的效果。  相似文献   

10.
Reactive Oxygen Species (ROS) are quintessential inflammatory compounds with oxidizing behavior. We have successfully developed a micellar system with responsiveness at the same time to two of the most important ROS: superoxide and hydrogen peroxide. This allows for an effective and selective capture of the two compounds and, in perspective, for inflammation-responsive drug release. The system is composed of superoxide dismutase (SOD) conjugated to oxidation-sensitive amphiphilic polysulfide/PEG block copolymers; the conjugate combines the SOD reactivity toward superoxide with that of hydrophobic thioethers toward hydrogen peroxide. Specifically, here we have demonstrated how this hybrid system can efficiently convert superoxide into hydrogen peroxide, which is then "mopped-up" by the polysulfides: this modus operandi is functionally analogous to the SOD/catalase combination, with the advantages of (a) being based on a single and more stable system, and (b) a higher overall efficiency due the physical proximity of the two ROS-reactive centers (SOD and polysulfides).  相似文献   

11.
Chen S  Zhang XZ  Cheng SX  Zhuo RX  Gu ZW 《Biomacromolecules》2008,9(10):2578-2585
Amphiphilic hyperbranched core-shell polymers with folate moieties as the targeting groups were synthesized and characterized. The core of the amphiphilic polymers was hyperbranched aliphatic polyester Boltorn H40. The inner part and the outer shell of the amphiphilic polymers were composed of hydrophobic poly(epsilon-caprolactone) segments and hydrophilic poly(ethylene glycol) (PEG) segments, respectively. To achieve tumor cell targeting property, folic acid was further incorporated to the surface of the amphiphilic polymers via a coupling reaction between the hydroxyl group of the PEG segment and the carboxyl group of folic acid. The polymers were characterized by (1)H NMR, (13)C NMR, and combined size-exclusion chromatography and multiangle laser light scattering analysis. The nanoparticles of the amphiphilic polymers prepared by dialysis method were characterized by transmission electron microscopy and particle size analysis. Two antineoplastic drugs, 5-fluorouracil and paclitaxel, were encapsulated into the nanoparticles. The drug release property and the targeting of the drug-loaded nanoparticles to different cells were evaluated in vitro. The results showed the drug-loaded nanoparticles exhibited enhanced cell inhibition because folate targeting increased the cytotoxicity of drug-loaded nanoparticles against folate receptor expressing tumor cells.  相似文献   

12.
Deoxyfluorocellulose acetates were prepared from cellulose acetate (CA, degree of substitution by acetyl groups: 2.2 and 1.7) by using diethylaminosulfur trifluoride (DAST) in 1,4-dioxane or diglyme. The maximum degree of substitution of fluorine of the products was approximately 0.60, and depolymerization was not significant during fluorination. The replacement of hydroxyl groups by fluorine atoms occurred exclusively at C-6, as confirmed by carbon-13 NMR spectroscopy. In the presence of pyridine, an N-pyridinium derivative of CA was obtained instead of a deoxyfluoro derivative of cellulose.  相似文献   

13.
Carboxymethyl Assam Bora rice starch (CM-ABRS) was chemically synthesized in non-aqueous medium with the optimum degree of substitution (DS) of 1.23, and physicochemically characterized by FT-IR, DSC, XRD, and SEM analysis. Comparative evaluation of CM-ABRS with native starch (ABRS) for powder flow characteristics, swelling index, apparent solubility, rheological properties, textural properties, and mucoadhesive studies were carried out. The aim of the current work was to investigate the potential of CM-ABRS as a novel carrier for the water-soluble chemotherapeutic, doxorubicin hydrochloride (DOX). Formation of drug/polymer complex (DOX-CM-ABRS) via electrostatic interaction has been evaluated for the controlled release of DOX in three different pH media (phosphate-buffered saline (PBS), pH 7.4, 6.8, and 5.5). In vitro drug release studies illustrated faster release of drug in PBS at pH 5.5 as compared to pH 6.8 and pH 7.4, respectively, indicating the importance of pH-sensitive drug release from the DOX-CM-ABRS complex in malignant tissues.  相似文献   

14.
In the present study, carboxymethyl chitosan was prepared from chitosan, crosslinked with glutaraldehyde and evaluated in vitro as a potential carrier for colon targeted drug delivery of ornidazole. Ornidazole was incorporated at the time of crosslinking of carboxymethyl chitosan. The chitosan was evaluated for its degree of deacetylation (DD) and average molecular weight; which were found to be 84.6% and 3.5×10(4) Da, respectively. The degree of substitution on prepared carboxymethyl chitosan was found to be 0.68. All hydrogel formulations showed more than 85% and 74% yield and drug loading, respectively. The swelling behaviour of prepared hydrogels checked in different pH values, 1.2, 6.8 and 7.4, indicated pH responsive swelling characteristic with very less swelling at pH 1.2 and quick swelling at pH 6.8 followed by linear swelling at pH 7.4 with slight increase. In vitro release profile was carried out at the same conditions as in swelling and drug release was found to be dependant on swelling of hydrogels and showed biphasic release pattern with non-fickian diffusion kinetics at higher pH. The carboxymethylation of chitosan, entrapment of drug and its interaction in prepared hydrogels were checked by FTIR, (1)H NMR, DSC and p-XRD studies, which confirmed formation of carboxymethyl chitosan from chitosan and absence of any significant chemical change in ornidazole after being entrapped in crosslinked hydrogel formulations. The surface morphology of formulation S6 checked before and after dissolution, revealed open channel like pores formation after dissolution.  相似文献   

15.
Amphiphilic graft copolymers consisting of poly(gamma-glutamic acid) (gamma-PGA) as the hydrophilic backbone and L-phenylalanine ethylester (L-PAE) as the hydrophobic side chain were synthesized by grafting L-PAE to gamma-PGA. The nanoparticles were prepared by a precipitation method, and about 200 nm-sized nanoparticles were obtained due to their amphiphilic properties. The hydrolytic and enzymatic degradation of these gamma-PGA nanoparticles was studied by gel permeation chromatography (GPC), scanning electron microscopy (SEM), dynamic light scattering (DLS) and (1)H NMR measurements. The hydrolysis ratio of gamma-PGA and these hydrophobic derivatives was found to decrease upon increasing the hydrophobicity of the gamma-PGA derivates. The pH had an effect on the hydrolytic degradation of the polymer. The hydrolysis of the polymer could be accelerated by alkaline conditions. The degradation of the gamma-PGA backbone by gamma-glutamyl transpeptidase (gamma-GTP) resulted in a dramatic change in nanoparticle morphology. With increasing time, the gamma-PGA nanoparticles began to decrease in size and finally disappeared completely. Moreover, the gamma-PGA nanoparticles were degraded by four different enzymes (Pronase E, protease, cathepsin B and lipase) with different degradation patterns. The enzymatic degradation of the nanoparticles occurred via the hydrolysis of gamma-PGA as the main chain and L-PAE as the side chain. In the case of the enzymatic degradation of gamma-PGA nanoparticles with Pronase E, the size of the nanoparticles increased during the initial degradation stage and decreased gradually when the degradation time was extended. Nanoparticles composed of biodegradable amphiphilic gamma-PGA with reactive function groups can undergo further modification and are expected to have a variety of potential pharmaceutical and biomedical applications, such as drug and vaccine carriers.  相似文献   

16.
Various deoxycholic acid (DOCA)-modified-carboxymethylated (CM)-curdlan (DCMC) were synthesized and characterized by FTIR, 1H NMR and XRD. The degree of DOCA substitution (DS), as spectrophotometrically determined, was 2.1, 3.2, 4.1, or 6.3 DOCA groups per hundred sugar residues of CM-curdlan. The physicochemical properties of the self-assembled nanoparticals in aqueous media were investigated using 1H NMR, dynamic light scattering, zeta potential, transmission electron microscopy (TEM) and fluorescence spectroscopy. DCMC conjugates provided monodispersed self-assembled nanoparticles in water, with mean diameter decreasing from 192 to 347 nm with DOCA DS increasing. Moreover, the mean diameter also increased with decreasing pH in PBS. Zeta potential of DCMC self-assembled nanoparticles exhibited near −60 mV in distilled water and −26 to −36 mV in PBS, indicating these nanoparticles were covered with negatively charged CM-curdlan shells. The critical aggregation concentration (cac) of the DCMC were dependent on the degree of substitution (DS) of DOCA and were slightly lower in PBS than in distilled water. The TEM images demonstrated that these self-assembled nanoparticles were of spherical shape.  相似文献   

17.
The main objective of the present work was to prepare warfarin-β-cyclodextrin (WAF-β-CD) loaded chitosan (CS) nanoparticles for transdermal delivery. CS is a hydrophilic carrier therefore, to overcome the hydrophobic nature of WAF and allow its incorporation into CS nanoparticles, WAF was first complexed with β-cyclodextrin (β-CD). CS nanoparticles were prepared by ionotropic pre-gelation using tripolyphosphate (TPP). Morphology, size and structure characterization of nanoparticles were carried out using SEM, TEM and FTIR, respectively. Nanoparticles prepared with 3:1 CS:TPP weight ratio and 2mg/ml final CS concentration were found optimum. They possessed spherical particles (35±12nm diameter) with narrow size distribution (PDI=0.364) and 94% entrapment efficiency. The in vitro release as well as the ex vivo permeation profiles of WAF-β-CD from the selected nanoparticle formulation were studied at different time intervals up to 8h. In vitro release of WAF-β-CD from CS nanoparticles followed a Higuchi release profile whereas its ex vivo permeation (at pH 7.4) followed a zero order permeation profile. Results suggested that the developed WAF-β-CD loaded CS carrier could offer a controlled and constant delivery of WAF transdermally.  相似文献   

18.
The aim of the present study was to design amphiphilic oligopeptides that can self-assemble into vesicular structures. The ratio of hydrophilic to hydrophobic block length was varied, and peptides were designed to have a hydrophobic tail in which the bulkiness of the amino acid side groups increases toward the hydrophilic domain (Ac-Ala-Ala-Val-Val-Leu-Leu-Leu-Trp-Glu(2/7)-COOH). These peptides were recombinantly produced in bacteria as an alternative to solid-phase synthesis. We demonstrate with different complementary techniques (dynamic and static light scattering, tryptophan fluorescence anisotropy, and electron microscopy) that these amphiphilic peptides spontaneously form vesicles with a radius of approximately 60 nm and a low polydispersity when dispersed in aqueous solution at neutral pH. Morphology and size of the vesicles were relatively insensitive to the variations in hydrophilic block length. Exposure to acidic pH resulted in formation of visible aggregates, which could be fully reversed to vesicles upon pH neutralization. In addition, it was demonstrated that water-soluble molecules can be entrapped inside these peptide vesicles. Such peptide vesicles may find applications as biodegradable drug delivery systems with a pH-dependent release profile.  相似文献   

19.
Peptide III is a 20-residue synthetic model peptide based on the fusion peptide of influenza virus A/PR/8/34 strain and takes a secondary structure similar to the original peptide. While conserving the amphiphilic helical nature, 20 peptides to modify the bulkiness of side chains of peptide III were synthesized, and acid-induced membrane destabilization was assessed by aqueous content leakage from large unilamellar vesicles. Substitutions on the hydrophobic side decreased activity but showed less effect on the hydrophilic side, which confirmed the importance of the hydrophobic side for interaction with the membrane. Interestingly, substitution at the 13th Gly residue enhanced the amphiphilic helical nature but severely reduced activity. Correlation between alpha-helical content at acidic pH and the activity was not recognized, suggesting rather that the importance of this site was due to helix termination by glycine which allows N-terminal and C-terminal halves to behave as different secondary structural units.  相似文献   

20.
In recent years, nanotechnology in merging with biotechnology has been employed in the area of cancer management to overcome the challenges of chemopreventive strategies in order to gain promising results. Since most biological processes occur in nano scale, nanoparticles can act as carriers of certain drugs or agents to deliver it to specific cells or targets. In this study, we intercalated Epigallocatechin-3-Gallate (EGCG), the most abundant polyphenol in green tea, into Ca/Al-NO3 Layered double hydroxide (LDH) nanoparticles, and evaluated its efficacy compared to EGCG alone on PC3 cell line. The EGCG loaded LDH nanohybrids were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM) and nanosizer analyses. The anticancer activity of the EGCG-loaded LDH was investigated in prostate cancer cell line (PC3) while the release behavior of EGCG from LDH was observed at pH 7.45 and 4.25. Besides enhancing of apoptotic activity of EGCG, the results showed that intercalation of EGCG into LDH can improve the anti- tumor activity of EGCG over 5-fold dose advantages in in-vitro system. Subsequently, the in-vitro release data showed that EGCG-loaded LDH had longer release duration compared to physical mixture, and the mechanism of diffusion through the particle was rate-limiting step. Acidic attack was responsible for faster release of EGCG molecules from LDH at pH of 4.25 compared to pH of 7.4. The results showed that Ca/Al-LDH nanoparticles could be considered as an effective inorganic host matrix for the delivery of EGCG to PC3 cells with controlled release properties.  相似文献   

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