• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Enhanced hyperthermia performance in hard-soft magnetic mixed Zn0.5CoxFe2.5?xO4/SiO2 composite magnetic nanoparticles?

    2021-03-19 03:21:04XiangYu俞翔LiChenWang王利晨ZhengRuiLi李崢睿YanMi米巖DiAnWu吳迪安andShuLiHe賀淑莉
    Chinese Physics B 2021年3期
    關(guān)鍵詞:迪安

    Xiang Yu(俞翔), Li-Chen Wang(王利晨), Zheng-Rui Li(李崢睿),Yan Mi(米巖), Di-An Wu(吳迪安), and Shu-Li He(賀淑莉)

    Department of Physics,Capital Normal University,Beijing 100048,China

    Keywords: magnetic nanoparticles,magnetic anisotropy,Zn0.5CoxFe2.5?xO4/SiO2,magnetic hyperthermia

    1. Introduction

    Iron oxide magnetic nanoparticles (NPs) have wide application prospects in biomedical field, for its advantage of stable chemical properties, excellent biocompatibility, appropriate magnetic properties, simplicity of preparation and tunable nature. The composite nanostructure is made by modifying SiO2, polyethylene glycol or polydopamine on the surface of the as-obtained NPs. The composite nanostructure displays extremely rich diagnostic and therapeutic functions in the fields of targeted drug release, magnetic resonance imaging, biological magnetic separation and magnetic hyperthermia.[1-8]Magnetic hyperthermia is a new kind of local tumor hyperthermia. Compared with the photohyperthermia which mainly uses near infrared laser with lower penetration depth,the alternating current(AC)magnetic field can penetrate into the body tissue to 15 cm and 99% of the electromagnetic energy is not absorbed by the human body.[9]Therefore, magnetic hyperthermia has unique superiorities in the treatment of deep tumors. The hyperthermia performance of traditional Fe3O4magnetic NPs is not very ideal, due to their certain limitations of magnetic properties.[10-12]Therefore,in an actual application process,we have to enhance the dosage of nano materials or the energy of AC field to meet the needs of hyperthermia, which certainly introduces a hidden danger to the safety of magnetic hyperthermia applications.

    In order to enhance the magnetic hyperthermia properties of Fe3O4-based magnetic NPs, Lee et al.prepared magnetic NPs with a core-shell structure(Zn0.4Co0.6Fe2O4@Zn0.4Mn0.6Fe2O4) in 2011. The saturation magnetization and magnetic anisotropy of the samples were effectively adjusted, a maximum specific power loss(SLP) value of 3886 W/g was successfully developed. This can be attributed to the soft and hard magnetic exchange coupling, based on theoretical calculations as a guide. The core-shell NPs can eliminate the tumor tissue of nude mice thoroughly, which is significantly better than the commercial Feridex control group and adriamycin chemotherapy control group.[12]However, because the core-shell NPs need to be grown by seed mediated method repeatedly and the size of the core and shell needs to be precisely controlled, these make the practical application of the samples difficult. In 2018, it was reported that the soft and hard magnetic coupling ferrite NPs were successfully prepared by doping Mn2+and Co2+directly to Fe3O4. The preparation of the NPs is easy to achieve, and the SLP value can approach the theoretical limit of 3417 W/gmetal. In vitro cell hyperthermia experiment,the use of low-dose magnetic NPs can effectively kill tumor cells in a very short time.[13]However, its biocompatibility is significantly lower than Fe3O4, which restricts its application in vivo. In recent research results,Zn0.5Fe2.5O4magnetic NPs were reported as typical soft ferrite NPs, which have excellent biocompatibility and good magnetic hyperthermia properties.[14]On the other hand, the theoretical simulation results indicated that the magnetic hyperthermia properties of soft ferrite NPs can be further improved significantly by properly increasing the magnetic anisotropy of the sample.[12]

    In this paper,Zn0.5CoxFe2.5?xO4(x=0,0.05, 0.1, 0.15)serial magnetic NPs were synthesized by doping Zn2+and Co2+ions to Fe3O4, to improve the saturation magnetization and magnetic anisotropy of the samples. The SiO2shell was modified on the surface of the series of NPs by reverse microemulsion method, to enhance the biocompatibility and water solubility of the NPs. The results show that the magnetic hyperthermia properties of the samples increase first and then decrease with the increase of Co2+doping amount. The peak SLP value of Zn0.5CoxFe2.5?xO4/SiO2samples can reach 1974 W/gmetalwith x=0.1.

    2. Experiments and methods

    2.1. Materials

    Fe(acac)3, Zn(acac)2·nH2O, Co(acac)2and ammonia(29%) were purchased from Alfa aesar; sodium oleate was purchased from TCI; tetraethyl orthosilicate (TEOS), igepal CO-520 and cyclohexane were purchased from Aldrich;oleic acid and benzyl ether were purchased from Acros.

    2.2. Synthesis of Zn0.5CoxFe2.5?xO4 magnetic nanoparticles

    Zn0.5CoxFe2.5?xO4magnetic NPs were prepared by the modified thermal decomposition method.[15]Firstly,2.5 mmol Fe(acac)3,0.5 mmol Zn(acac)2·nH2O and Co(acac)2,2 mmol sodium oleate,4.5 mL oleic acid and 20 mL benzyl ether were added to the four neck flask. Under the protection of argon,the mixture was heated to 120?C,and kept for 30 min to remove impurities with low boiling point. Then the mixture was heated to 295?C with the rate of 10?C/min, and maintained for 2 h. Finally, the heating device is removed so that the reaction system can be cooled to room temperature,and ethanol is added and centrifuged to separate the NPs.

    2.3. Silica coating of Zn0.5CoxFe2.5?xO4 magnetic nanoparticles

    SiO2was coated on the surface of NPs via reverse microemulsion method.[16]First, 20 mL cyclohexane and 1.15 mL CO-520 were added to the flask, and mixed thoroughly with sonication bath for 10 min. Then 20 mg Zn0.5CoxFe2.5?xO4magnetic NPs and 1 mL cyclohexane were added into an eppendorf tube,thoroughly mixed by sonication bath, and then transferred into the flask. After the mixture was sonicated for 20 min,0.15 mL ammonia was added dropwise and magnetically stirred for 10 min. Finally, 0.1 mL of TEOS was added and reacted for 24 hours.The as-synthesized Zn0.5CoxFe2.5?xO4/SiO2composite NPs are separated by centrifugation by adding ethanol and hexane.

    2.4. Characterization

    The morphology of NPs was observed with a transmission electron microscope (TEM, Hitachi H-7650); the highresolution TEM images were obtained by an FEI Tecnai G2 F30 TEM;the crystal structure was characterized by an x-ray diffractometer(XRD,Bruker D8 advance);the magnetic properties were measured by a commercial superconducting quantum interference device magnetometer (SQUID-VSM). The field-dependent magnetization curves (M-H) were recorded from 0 to ±5 T at 300 K and 10 K. Temperature-dependent magnetization curves(M-T)were measured under zero-fieldcooled/field-cooled (ZFC/FC) mode from 10 K to 300 K under a magnetic field of 500 Oe;and the magnetic hyperthermia properties were measured by MSI HYPER 5 machine.

    2.5. Calculation of SLP and ILP values

    The specific loss power (SLP) is introduced to evaluate the magnetic hyperthermia properties of the samples,which is expressed as

    where C is the volume specific heat capacity,Vsis the volume of the sample, m is the mass of the metallic elements of the NPs in the sample, dT/dt is the initial slope of the temperature rise curve.

    According to the research,the hyperthermia properties of materials can be more essentially reflected by deducting the amplitude and frequency of AC field from SLP values. Therefore,the intrinsic loss power(ILP)is introduced for evaluation,which is expressed as

    where H is the amplitude of the AC field and f is the frequency of the AC field.

    2.6. In vitro experiments

    The cytotoxicity of the Zn0.5CoxFe2.5?xO4/SiO2composite NPs was assessed using in vitro cell toxicity assay. Mouse fibroblast cells (MEF) purchased from the American Type Culture Collection were seeded in 96-well plates at a density of 5000 cells per well. Then, different concentrations of the Zn0.5CoxFe2.5?xO4/SiO2composite NPs were added to the wells and incubated for 24 h further. The cell viabilities were determined by the standard Cell Counting Kit-8(CCK-8,Dojindo,Japan)assay.

    3. Results and discussion

    Our approach is schematically shown in Fig.1.Zn0.5CoxFe2.5?xO4NPs were synthesized using sodium oleate instead of oleamine and 1,2-hexadecanediol in the classic formulation. This modified thermal decomposition method can save material and time cost more effectively.[15,17-20]Silica coating of Zn0.5CoxFe2.5?xO4NPs was performed via the reverse microemulsion method.[16]The hyperthermia properties of Zn0.5CoxFe2.5?xO4/SiO2composite NPs were systematically studied under AC field.

    Fig.1. Scheme of the synthetic route and research method of Zn0.5CoxFe2.5?xO4/SiO2 NPs.

    As shown in Fig.2,XRD patterns of Zn0.5CoxFe2.5?xO4(x = 0, 0.05, 0.1, 0.15) serial NPs and the standard patterns of Zn0.54Fe2.46O4(PDF card #86-0509, Fdˉ3m) match so well. All the peaks can be indexed, which indicates that the Zn0.5CoxFe2.5?xO4(x=0,0.05,0.1,0.15)serial NPs have single spinel cubic phase structures.

    Fig.2. XRD patterns of Zn0.5CoxFe2.5?xO4 (x=0, 0.05, 0.1, 0.15)serial NPs.

    Using the modified thermal decomposition method, we have synthesized magnetic NPs with controllable size and morphology using sodium oleate instead of oleamine and 1,2-hexadecanediol in the classical formula.[15]It can be seen from Fig.3 that Zn0.5CoxFe2.5?xO4(x=0, 0.05, 0.1, 0.15) serial NPs with stable morphology at 21 nm and good monodispersity were synthesized using the ratio of 3 mmol metal precursor,2 mmol sodium oleate,4 mL oleic acid and 20 mL benzyl ether.

    The surface of the NPs was coated with SiO2via the reverse microemulsion method, as shown in Fig.4. It can be seen that Zn0.5CoxFe2.5?xO4/SiO2(x=0,0.05,0.1,0.15)serial samples have uniform size,uniform coating of SiO2shell,no defect, thickness of about 6 nm, and no formation of free SiO2shell. In addition,it can be seen from the high-resolution TEM images that the SiO2shell can fully and uniformly coat the magnetic nanoparticle. This can be attribute to the precise control of the volume ratio of ammonia and TEOS in the reaction(0.15 mL:0.1 mL),in which the concentration of hydrolyzed TEOS monomer is always controlled in the range of heterogeneous nucleation, and the unexpected homogeneous nucleation will be avoided.[16]

    Fig.3. TEM images of Zn0.5CoxFe2.5?xO4: (a)x=0,(b)x=0.05,(c)x=0.1,(d)x=0.15 NPs.

    Fig.4. TEM images of Zn0.5CoxFe2.5?xO4/SiO2: (a) x=0, (b) x=0.05,(c)x=0.1,(d)x=0.15 composite NPs.The insets show the highresolution TEM images of the corresponding Zn0.5CoxFe2.5?xO4/SiO2 composite NPs.

    The magnetic properties of Zn0.5CoxFe2.5?xO4(x = 0,0.05, 0.1, 0.15) serial samples were measured by SQUIDVSM. In earlier research, the saturation magnetization of Zn0.5Fe2.5O4with Zn2+ion partially replaces Fe2+ions in Fe3O4was effectively enhanced.[21]We further measured the M-H curves of Zn0.5CoxFe2.5?xO4serial samples at 300 K and 10 K, as shown in Fig.5. From the saturation magnetization on the data measured at 300 K, the saturation magnetization decreases monotonously with the increase of the doping amount of Co2+ions. From the doping amount of 0 to 0.15,the saturation magnetization decreases from 85.5 emu/g to 79.3 emu/g. This can be due to the fact that the magnetic moment of original Fe2+ions(4μB)is bigger than Co2+ions(3μB).In addition,the M-H data measured at 10 K also shows a consistent trend of change,in which the saturation magnetization decreases from 94.2 emu/g to 87.5 emu/g with doping amount from 0 to 0.15. The coercivity (Hc) of the samples increases from 262 Oe to 3500 Oe with the increase of the amount of Co2+ions in the data measured at 10 K, which shows that the doping of traditional hard magnetic Co2+ions can effectively increase the magnetic anisotropy of the samples. The law of coercivity change at 300 K is different from that at 10 K, showing a magnetic phase transition process.The coercivity of the samples remains about 5 Oe with the increase of Co2+ion content from 0 to 0.05,showing a plateau region where the coercivity does not increase with the doping amount. This is normally contributed to superparamagnetism in samples. From the M-T curves shown in Figs.5(e)and 5(f), it can be seen that the blocking temperature (TB)of Zn0.5Fe2.5O4and Zn0.5Co0.05Fe2.45O4is less than 300 K.Therefore,the results also confirm that the samples have superparamagnetism at room temperature. On the other hand, the coercivity increases to about 11 Oe when the doping amount of Co2+ion is 0.1,and reaches 17 Oe with doping amount of 0.15.

    Fig.5. M-H curves of Zn0.5CoxFe2.5?xO4 (x=0, 0.05, 0.1, 0.15) NPs at (a) 300 K and (b) 10 K; Co content dependence of (c) saturation magnetization Ms and(d)coercivity Hc for Zn0.5CoxFe2.5?xO4 NPs,measured at 300 K and 10 K;M-T curves of(e)Zn0.5Fe2.5O4 NPs and(f)Zn0.5Co0.05Fe2.45O4NPs. The curves are normalized to the values at T =10 K.

    According to the above phenomenon, the change of the whole magnetic phase can be divided into two sections. It can be inferred that the transition point from superparamagnetism to ferrimagnetism is x ~0.1 in this study. In addition,we can clearly see from the M-H curves that there is obvious magnetic phase separation when doping amount is 0.15, which is normally classify as the co-existence of soft and hard magnetic phases. According to the experimental results in the literature,this may be related to the large amount of ion doping in the sample.[15]

    The magnetic hyperthermia properties of Zn0.5CoxFe2.5?xO4/SiO2(x=0,0.05,0.1,0.15)serial samples were measured at a concentration of 1 mg/mL,as shown in Fig.6. The heating performance of the four samples increases monotonously with the increase of AC field amplitude, when the frequency of AC field is maintained at 430 kHz. This is consistent with the description of Rosensweig’s theoretical equation[22]

    where μ0is the the vacuum permeability, χ0is the equilibrium susceptibility, H is the amplitude of the AC field, f is the frequency of the AC field (f =ω/2π), and τ is the total relaxation time of the magnetic NPs in the AC field.

    Fig.6. Heating curves of Zn0.5CoxFe2.5?xO4/SiO2 under different magnetic field amplitudes, with the AC field of 430 kHz: (a) x=0, (b)x=0.05,(c)x=0.1,(d)x=0.15.

    Using the heating curves of each sample under the highest AC field(31 kA/m,430 kHz),the corresponding SLP value can be calculated. It can be seen from Fig.7(a) that the SLP value shows a trend of first increasing and then decreasing with the increase of Co2+ion doping, and reaches the peak value with 1974 W/gmetalwhen x=0.1. It can be concluded that the magnetic hyperthermia properties of Zn0.5Fe2.5O4samples can be improved by Co2+doping. The earlier literature reported that SLP value does not always monotonously rise,and the best position is near the transition point of magnetic NPs from superparamagnetism to ferrimagnetism.[23-25]In our research,the peak SLP value emerges at x=0.1,consistent with the magnetic measurement data and the explanation in the earlier report.

    The magnetic anisotropy continues to increase and the magnetic NPs enter the ferrimagnetic region when the Co2+ions are further increased (x=0.15), which makes the magnetic moment of the sample unable to be effectively reversed by the AC field. On the other hand,the saturation magnetization of the sample has dropped to 79.3 emu/g when the doping amount is x=0.15. According to the research results of the literature,the loss power will also be significantly reduced.[12]Finally,it can be seen from the change diagram of SLP value with Co2+doping amount that the SLP value will be significantly decreased at this time.

    On the other hand,the total relaxation time,which is composed of Brown relaxation time and N′eel relaxation time,will affect the loss power,from the formula of linear response theory. In this paper, the N′eel relaxation time will be mainly affected by adjusting the magnetic anisotropy of the sample,which is expressed as

    where τ0is the time constant(τ0~10?9s),K is the anisotropy constant,V is the volume of nanoparticle,and kBis the Boltzmann constant. In the literature, a theoretical simulation is made based on the linear response theory. From the simulation results,it can be clearly seen that there is a non-monotonic response relationship between the anisotropy constant K and the SLP value of the magnetic NPs. That is,with the increase of the anisotropy constant, the SLP value presents a process of increasing first and then decreasing. This means that under a certain AC field,magnetic NPs need to have an appropriate K value to obtain the maximum SLP value. In our work, the variation of SLP with the anisotropic constant K is in good agreement with the theoretical simulation in the literature. An optimal K value under the AC field is achieved when the Co2+ion doping amount is 0.1. Therefore, it has the highest SLP value in the series of samples.[12,22,26,27]

    The change chart of ILP with the amount of Co2+ion doping is obtained by removing the influence of AC field amplitude and frequency from the SLP value. As shown in Fig.7(b), it can be seen from the chart that the trend of ILP values is consistent with the change of SLP values with the amount of Co2+ion doping, with a peak value of 4.77 nHm2/kgmetalwith Co2+ion doping amount is 0.1.

    Fig.7.(a)SLP and(b)ILP for Zn0.5CoxFe2.5?xO4/SiO2 composite NPs under the AC field of 430 kHz and 31 kA/m.

    Cytotoxicity of Zn0.5CoxFe2.5?xO4/SiO2composite NPs to MEF cells was measured and studied. The different concentrations of Zn0.5CoxFe2.5?xO4/SiO2composite NPs ranging from 25 to 1000μg/mL were incubated with the cells for 24 h. After the incubation period, the viability of the MEF cells was assessed by CCK-8. Cells without NPs were used as control groups. Compared to the group without NPs, as shown in Fig.8,the group containing different concentrations of Zn0.5CoxFe2.5?xO4/SiO2composite NPs shows no significant difference in cell viability at the incubation time of up to 24 h. Though at 1000μg/mL after incubation for 24 h,viability of MEF cells with NPs is nearly 100%,which suggests that the materials are biocompatible.

    Fig.8. The viability of the MEF cells determined by CCK-8 assay after incubation in NP solutions with various concentrations for 24 h.

    4. Conclusion

    In summary, a series of high-quality Zn0.5CoxFe2.5?xO4(x = 0, 0.05, 0.1, 0.15) samples were synthesized by the modified thermal decomposition method. The saturation magnetization of the sample is improved and the magnetic anisotropy of the sample is controlled by doping Zn2+and Co2+ions into Fe3O4. A transition point from superparamagnetism to ferrimagnetism is found with Co2+content of 0.1. A peak SLP value of 1974 W/gmetalhas been found in Zn0.5Co0.1Fe2.4O4/SiO2, which corresponds to the magnetic properties. In addition, the NPs show excellent biocompatibility in vitro. The composite NPs are expected to be a good candidate material in applications of magnetic hyperthermia.

    猜你喜歡
    迪安
    Inversion techniques to obtain local rotation velocity and ion temperature profiles for the x-ray crystal spectrometer on EAST
    助瀾冷戰(zhàn)——迪安·艾奇遜與戰(zhàn)后美蘇原子能合作的破產(chǎn)
    公交站里的背影
    中外文摘(2021年22期)2021-12-30 02:17:18
    Effects of dipolar interactions on the magnetic hyperthermia of Zn0.3Fe2.7O4 nanoparticles with different sizes*
    阿維迪安黃金公司簡(jiǎn)介
    “彗星”成明星,拯救兩條人命的竟是一條小金魚
    朝鮮戰(zhàn)爭(zhēng)中頭號(hào)美軍戰(zhàn)俘迪安少將
    對(duì)不起,我愛(ài)你
    新青年(2017年11期)2017-11-23 18:30:47
    光榮的神槍手
    他鄉(xiāng)
    文學(xué)港(2016年3期)2016-03-17 15:28:41
    国产黄片视频在线免费观看| 国产极品天堂在线| 亚洲av成人精品一区久久| 成人鲁丝片一二三区免费| 丰满少妇做爰视频| 久久韩国三级中文字幕| 99九九线精品视频在线观看视频| 亚州av有码| 亚洲国产精品sss在线观看| 亚洲av日韩在线播放| 两性午夜刺激爽爽歪歪视频在线观看| 成年av动漫网址| 久久久久久久国产电影| 国产乱人偷精品视频| 亚洲成人久久爱视频| 一本久久精品| 午夜亚洲福利在线播放| 日韩三级伦理在线观看| 成人国产麻豆网| h日本视频在线播放| 少妇人妻精品综合一区二区| 少妇被粗大猛烈的视频| 91午夜精品亚洲一区二区三区| 国产老妇女一区| 国产精品精品国产色婷婷| 国产三级中文精品| 夫妻性生交免费视频一级片| 联通29元200g的流量卡| 天天躁日日操中文字幕| 美女xxoo啪啪120秒动态图| 欧美日韩在线观看h| 亚洲国产精品sss在线观看| 国产成年人精品一区二区| 亚洲aⅴ乱码一区二区在线播放| 午夜激情福利司机影院| 国产成人a区在线观看| 人人妻人人看人人澡| 秋霞伦理黄片| 夜夜爽夜夜爽视频| 黄色欧美视频在线观看| 亚洲国产精品久久男人天堂| 一卡2卡三卡四卡精品乱码亚洲| 国产69精品久久久久777片| 午夜福利在线观看吧| 久久99热这里只频精品6学生 | 午夜福利在线观看免费完整高清在| 赤兔流量卡办理| 国产精品麻豆人妻色哟哟久久 | 国内揄拍国产精品人妻在线| 性插视频无遮挡在线免费观看| 麻豆乱淫一区二区| 国产精品国产三级国产专区5o | 欧美日韩综合久久久久久| 伦理电影大哥的女人| 97人妻精品一区二区三区麻豆| 久久精品综合一区二区三区| 99热6这里只有精品| 成人午夜精彩视频在线观看| 在线观看av片永久免费下载| 18禁在线播放成人免费| 一卡2卡三卡四卡精品乱码亚洲| 日韩,欧美,国产一区二区三区 | 精品人妻一区二区三区麻豆| 欧美高清成人免费视频www| 亚洲在线自拍视频| 18禁动态无遮挡网站| 久久精品国产亚洲网站| 久久99热6这里只有精品| 免费一级毛片在线播放高清视频| 亚洲成色77777| 国产av码专区亚洲av| 国产乱人视频| 汤姆久久久久久久影院中文字幕 | 午夜精品国产一区二区电影 | 男女那种视频在线观看| 晚上一个人看的免费电影| 亚洲天堂国产精品一区在线| 亚洲欧美精品自产自拍| 久久久精品欧美日韩精品| 美女内射精品一级片tv| 亚洲综合精品二区| 免费观看的影片在线观看| 国产真实乱freesex| 午夜精品国产一区二区电影 | 亚洲一区高清亚洲精品| 网址你懂的国产日韩在线| 最新中文字幕久久久久| 久久精品久久精品一区二区三区| 亚洲av电影不卡..在线观看| 精品不卡国产一区二区三区| 国产精品,欧美在线| 日韩,欧美,国产一区二区三区 | 九九热线精品视视频播放| 男女边吃奶边做爰视频| or卡值多少钱| 岛国在线免费视频观看| 久久国内精品自在自线图片| 国产亚洲精品久久久com| 国模一区二区三区四区视频| 欧美极品一区二区三区四区| 久久精品91蜜桃| 亚洲国产欧美在线一区| 少妇熟女欧美另类| 99久久九九国产精品国产免费| 国产 一区精品| 免费不卡的大黄色大毛片视频在线观看 | 精品久久久久久成人av| 99视频精品全部免费 在线| 爱豆传媒免费全集在线观看| 国产中年淑女户外野战色| 亚洲国产日韩欧美精品在线观看| 26uuu在线亚洲综合色| 六月丁香七月| 国产在线男女| www日本黄色视频网| 日韩av在线大香蕉| 亚洲av电影不卡..在线观看| 尤物成人国产欧美一区二区三区| 欧美高清性xxxxhd video| 久久久a久久爽久久v久久| 中文字幕制服av| 国产亚洲午夜精品一区二区久久 | 热99re8久久精品国产| 国产一区二区三区av在线| 天天躁夜夜躁狠狠久久av| 久久久午夜欧美精品| av国产免费在线观看| АⅤ资源中文在线天堂| 国产高清国产精品国产三级 | 免费观看性生交大片5| av卡一久久| 亚洲欧美精品综合久久99| 看十八女毛片水多多多| 国产精品国产三级国产av玫瑰| 国内精品宾馆在线| 麻豆成人av视频| 国产一区二区在线观看日韩| 国产精品熟女久久久久浪| 可以在线观看毛片的网站| 国产亚洲5aaaaa淫片| 观看美女的网站| 18禁动态无遮挡网站| 亚洲国产精品合色在线| 三级国产精品欧美在线观看| 国产精品一区二区性色av| 国产精品av视频在线免费观看| 日韩高清综合在线| kizo精华| 免费av毛片视频| 麻豆成人午夜福利视频| 国产探花在线观看一区二区| 国产伦一二天堂av在线观看| 欧美变态另类bdsm刘玥| 女人久久www免费人成看片 | 少妇熟女欧美另类| 国产69精品久久久久777片| 日韩欧美国产在线观看| 国产精品综合久久久久久久免费| 一区二区三区四区激情视频| 99久久成人亚洲精品观看| 欧美激情国产日韩精品一区| 天天一区二区日本电影三级| 国产熟女欧美一区二区| 又粗又爽又猛毛片免费看| 色吧在线观看| 99在线人妻在线中文字幕| 观看美女的网站| av线在线观看网站| 亚洲精品乱码久久久久久按摩| 视频中文字幕在线观看| 天堂网av新在线| 婷婷色麻豆天堂久久 | 尾随美女入室| 日韩欧美 国产精品| 看非洲黑人一级黄片| 日韩av不卡免费在线播放| 精品人妻偷拍中文字幕| 国产伦精品一区二区三区视频9| 国产精品熟女久久久久浪| 欧美日本视频| 亚洲精品乱久久久久久| 最近的中文字幕免费完整| 成人高潮视频无遮挡免费网站| 国产一区二区在线观看日韩| 最近最新中文字幕免费大全7| 成人国产麻豆网| 国产亚洲精品久久久com| 欧美潮喷喷水| 边亲边吃奶的免费视频| 亚洲怡红院男人天堂| 亚洲精品色激情综合| 国产黄a三级三级三级人| 成人无遮挡网站| 亚洲国产精品国产精品| 22中文网久久字幕| 国产精品精品国产色婷婷| 大香蕉97超碰在线| 国产乱来视频区| 亚洲精品一区蜜桃| 亚洲丝袜综合中文字幕| 国产精品久久久久久久电影| 国产一区二区在线观看日韩| 淫秽高清视频在线观看| 国产高清国产精品国产三级 | 精品人妻一区二区三区麻豆| 黄色欧美视频在线观看| 精品酒店卫生间| 91aial.com中文字幕在线观看| 国产亚洲午夜精品一区二区久久 | 寂寞人妻少妇视频99o| 亚洲国产精品sss在线观看| 国产精品人妻久久久影院| 日日干狠狠操夜夜爽| 成年免费大片在线观看| 亚洲中文字幕一区二区三区有码在线看| 亚洲最大成人av| 国产av一区在线观看免费| 久久久午夜欧美精品| videossex国产| 国产午夜精品一二区理论片| 国产精品一及| 国产一级毛片在线| 又粗又爽又猛毛片免费看| 亚洲精品影视一区二区三区av| 国产精品野战在线观看| av在线观看视频网站免费| 爱豆传媒免费全集在线观看| 两个人视频免费观看高清| 99久国产av精品| 亚洲精华国产精华液的使用体验| 在线天堂最新版资源| 亚洲成人中文字幕在线播放| 日韩强制内射视频| 成人性生交大片免费视频hd| 欧美极品一区二区三区四区| 成人毛片60女人毛片免费| 国产男人的电影天堂91| 亚洲aⅴ乱码一区二区在线播放| 国产片特级美女逼逼视频| 99久久成人亚洲精品观看| 欧美不卡视频在线免费观看| av国产免费在线观看| 国产成人免费观看mmmm| 超碰av人人做人人爽久久| 精品无人区乱码1区二区| 亚洲成av人片在线播放无| 免费av毛片视频| 桃色一区二区三区在线观看| 99视频精品全部免费 在线| 超碰av人人做人人爽久久| 晚上一个人看的免费电影| 亚洲,欧美,日韩| 日韩精品青青久久久久久| 搡女人真爽免费视频火全软件| 精品久久国产蜜桃| 国产精品熟女久久久久浪| 亚洲在线观看片| 身体一侧抽搐| 国产成年人精品一区二区| 能在线免费看毛片的网站| 天堂网av新在线| 少妇被粗大猛烈的视频| 国产乱来视频区| 国产免费福利视频在线观看| 18禁裸乳无遮挡免费网站照片| 熟妇人妻久久中文字幕3abv| 一边亲一边摸免费视频| 久久久久久久久久久丰满| 国产精品国产三级专区第一集| 插阴视频在线观看视频| 老司机影院毛片| 久久综合国产亚洲精品| 成人一区二区视频在线观看| 国产私拍福利视频在线观看| 如何舔出高潮| 少妇人妻一区二区三区视频| 能在线免费观看的黄片| av.在线天堂| 91在线精品国自产拍蜜月| 啦啦啦韩国在线观看视频| 国产av在哪里看| 国产精品女同一区二区软件| 一区二区三区乱码不卡18| 亚洲不卡免费看| 黄色日韩在线| 亚洲精品,欧美精品| 国产黄a三级三级三级人| 久久久久网色| 国产老妇女一区| 日本爱情动作片www.在线观看| 麻豆一二三区av精品| 高清日韩中文字幕在线| 欧美成人午夜免费资源| 日本色播在线视频| 成人二区视频| 欧美日本亚洲视频在线播放| 久久人人爽人人片av| 日本-黄色视频高清免费观看| 69av精品久久久久久| 国产亚洲精品av在线| 26uuu在线亚洲综合色| 亚洲av一区综合| 五月伊人婷婷丁香| 国产亚洲91精品色在线| 日日摸夜夜添夜夜爱| 日韩制服骚丝袜av| 视频中文字幕在线观看| 老司机福利观看| av天堂中文字幕网| 日韩欧美三级三区| 国产av一区在线观看免费| eeuss影院久久| 丰满少妇做爰视频| 亚洲不卡免费看| 三级经典国产精品| 美女国产视频在线观看| 日韩高清综合在线| 国产精品麻豆人妻色哟哟久久 | 国产亚洲精品av在线| 日本午夜av视频| 春色校园在线视频观看| 国产亚洲av片在线观看秒播厂 | 天堂网av新在线| 又粗又爽又猛毛片免费看| 美女xxoo啪啪120秒动态图| 久久久久性生活片| 亚洲性久久影院| 少妇被粗大猛烈的视频| 91在线精品国自产拍蜜月| 亚洲国产成人一精品久久久| 欧美高清成人免费视频www| 久久久亚洲精品成人影院| 精品国产三级普通话版| 日本av手机在线免费观看| 人妻少妇偷人精品九色| 老司机影院成人| 日韩一区二区视频免费看| 欧美日韩在线观看h| 狠狠狠狠99中文字幕| 女的被弄到高潮叫床怎么办| av.在线天堂| 丰满乱子伦码专区| 在线免费观看不下载黄p国产| 免费av观看视频| 精品久久久久久久久亚洲| 一本久久精品| 小蜜桃在线观看免费完整版高清| 国产精品国产三级专区第一集| 狠狠狠狠99中文字幕| 欧美极品一区二区三区四区| 欧美日韩综合久久久久久| 日韩制服骚丝袜av| 亚洲欧美中文字幕日韩二区| 国产亚洲精品av在线| 色吧在线观看| 国产精品伦人一区二区| 国产一级毛片七仙女欲春2| 国产精品日韩av在线免费观看| 老司机福利观看| 美女脱内裤让男人舔精品视频| 亚洲av.av天堂| 久久精品夜色国产| 人人妻人人澡人人爽人人夜夜 | 亚洲最大成人中文| 亚洲综合色惰| 国产精品国产三级国产专区5o | av在线天堂中文字幕| 午夜福利成人在线免费观看| 一区二区三区高清视频在线| 欧美zozozo另类| 亚洲欧美日韩东京热| 综合色丁香网| 女人久久www免费人成看片 | 天天躁夜夜躁狠狠久久av| 午夜爱爱视频在线播放| 神马国产精品三级电影在线观看| 日本黄色片子视频| 哪个播放器可以免费观看大片| 色视频www国产| 日韩一本色道免费dvd| 国模一区二区三区四区视频| 日韩欧美在线乱码| 色噜噜av男人的天堂激情| 好男人在线观看高清免费视频| 日韩欧美在线乱码| 亚洲怡红院男人天堂| 建设人人有责人人尽责人人享有的 | 日韩一区二区三区影片| 色综合色国产| 亚洲av一区综合| 亚洲,欧美,日韩| 校园人妻丝袜中文字幕| 伦理电影大哥的女人| 毛片一级片免费看久久久久| 高清午夜精品一区二区三区| 亚洲国产色片| 国产极品天堂在线| 91精品国产九色| 色噜噜av男人的天堂激情| 九九爱精品视频在线观看| 国产精品人妻久久久影院| 国产成人a区在线观看| 欧美精品国产亚洲| 赤兔流量卡办理| 嫩草影院精品99| 尾随美女入室| 日日摸夜夜添夜夜爱| h日本视频在线播放| 欧美成人a在线观看| 精品国产一区二区三区久久久樱花 | 久热久热在线精品观看| 久久这里只有精品中国| 国产一区有黄有色的免费视频 | 99九九线精品视频在线观看视频| 日本熟妇午夜| 亚洲高清免费不卡视频| 亚洲第一区二区三区不卡| 国产淫片久久久久久久久| 男的添女的下面高潮视频| 中文字幕精品亚洲无线码一区| 汤姆久久久久久久影院中文字幕 | 中文字幕人妻熟人妻熟丝袜美| 国产精品,欧美在线| 国产高清三级在线| 精品国产三级普通话版| 成人鲁丝片一二三区免费| 亚洲欧美清纯卡通| 真实男女啪啪啪动态图| 亚洲自拍偷在线| 好男人在线观看高清免费视频| 两性午夜刺激爽爽歪歪视频在线观看| 日本免费a在线| 白带黄色成豆腐渣| 亚洲最大成人手机在线| 亚洲精品乱码久久久久久按摩| 欧美xxxx性猛交bbbb| 最近中文字幕2019免费版| 成人三级黄色视频| 亚洲伊人久久精品综合 | 日本熟妇午夜| 黄片无遮挡物在线观看| 一级毛片我不卡| 麻豆一二三区av精品| 国产伦精品一区二区三区视频9| 久久精品夜色国产| 国产真实伦视频高清在线观看| 中文字幕免费在线视频6| 免费av毛片视频| 午夜精品一区二区三区免费看| 亚洲av男天堂| 亚洲国产成人一精品久久久| 国产乱人视频| 18禁裸乳无遮挡免费网站照片| 国产精品人妻久久久久久| 少妇被粗大猛烈的视频| 久久久国产成人免费| 少妇高潮的动态图| av免费在线看不卡| 人妻少妇偷人精品九色| 我的老师免费观看完整版| 51国产日韩欧美| 亚洲自拍偷在线| 欧美高清性xxxxhd video| 爱豆传媒免费全集在线观看| 黄色欧美视频在线观看| 日韩制服骚丝袜av| 午夜激情欧美在线| 成年版毛片免费区| 综合色av麻豆| 亚洲国产精品合色在线| 一个人观看的视频www高清免费观看| 夜夜看夜夜爽夜夜摸| 国产成人aa在线观看| 午夜福利在线在线| 内地一区二区视频在线| 国产精品一区二区三区四区久久| 国产伦理片在线播放av一区| 性插视频无遮挡在线免费观看| 大话2 男鬼变身卡| 美女高潮的动态| 日本wwww免费看| 大又大粗又爽又黄少妇毛片口| 国产精品一区二区三区四区久久| 日韩 亚洲 欧美在线| 国产探花极品一区二区| 欧美xxxx黑人xx丫x性爽| 边亲边吃奶的免费视频| 免费看日本二区| 免费av毛片视频| 国产伦精品一区二区三区四那| 日本猛色少妇xxxxx猛交久久| 日本一本二区三区精品| 久久99精品国语久久久| 亚洲综合精品二区| 91狼人影院| 五月玫瑰六月丁香| 99久久人妻综合| 男女下面进入的视频免费午夜| 中文在线观看免费www的网站| 亚洲国产欧美人成| 黄色一级大片看看| 精品一区二区三区视频在线| 91aial.com中文字幕在线观看| 在线播放国产精品三级| 男女国产视频网站| 国产精品一区二区在线观看99 | 国产老妇伦熟女老妇高清| av播播在线观看一区| 高清在线视频一区二区三区 | 一本一本综合久久| 欧美激情久久久久久爽电影| 丰满乱子伦码专区| 可以在线观看毛片的网站| АⅤ资源中文在线天堂| 99热这里只有是精品50| 99热网站在线观看| 老司机福利观看| 久久精品国产自在天天线| 一卡2卡三卡四卡精品乱码亚洲| 国产成年人精品一区二区| 国产伦理片在线播放av一区| 18禁裸乳无遮挡免费网站照片| 神马国产精品三级电影在线观看| 久久久久久久久久久丰满| 一级毛片电影观看 | 亚洲av电影在线观看一区二区三区 | 久久久久久久久久黄片| 午夜激情欧美在线| 精品一区二区三区人妻视频| 一二三四中文在线观看免费高清| 久久久a久久爽久久v久久| 色综合亚洲欧美另类图片| 亚洲人成网站高清观看| 美女国产视频在线观看| av线在线观看网站| 久久久成人免费电影| 国产精品野战在线观看| 91精品伊人久久大香线蕉| 人妻夜夜爽99麻豆av| 欧美成人精品欧美一级黄| 亚洲熟妇中文字幕五十中出| 亚洲最大成人中文| 国产真实乱freesex| 久久精品国产自在天天线| 免费人成在线观看视频色| 嫩草影院新地址| 人妻夜夜爽99麻豆av| 特大巨黑吊av在线直播| 国产成人福利小说| 亚洲av二区三区四区| 午夜激情福利司机影院| 久久久久久伊人网av| 中国美白少妇内射xxxbb| 亚洲欧美清纯卡通| 国产 一区精品| 啦啦啦观看免费观看视频高清| av在线播放精品| 欧美一区二区精品小视频在线| 成年av动漫网址| 色综合站精品国产| 18+在线观看网站| 日本av手机在线免费观看| 国内精品一区二区在线观看| 能在线免费看毛片的网站| 边亲边吃奶的免费视频| 色视频www国产| 免费播放大片免费观看视频在线观看 | 国产乱来视频区| 午夜a级毛片| 亚洲丝袜综合中文字幕| 亚洲五月天丁香| 午夜福利在线在线| 丝袜喷水一区| 日日干狠狠操夜夜爽| ponron亚洲| 亚洲精品一区蜜桃| 欧美一区二区亚洲| 亚洲av日韩在线播放| 精品久久久久久成人av| 国产精品爽爽va在线观看网站| 在线天堂最新版资源| 国产精品伦人一区二区| 有码 亚洲区| 网址你懂的国产日韩在线| 久久久久性生活片| 亚洲18禁久久av| 色综合色国产| 日韩高清综合在线| 亚洲精品aⅴ在线观看| 在线免费观看不下载黄p国产| 国产极品天堂在线| 免费看av在线观看网站| 国产一区二区在线观看日韩| 九九爱精品视频在线观看| 国产私拍福利视频在线观看| 最近最新中文字幕大全电影3| 国产精品人妻久久久影院| 成人午夜精彩视频在线观看| 亚洲国产精品成人综合色| 午夜日本视频在线| 真实男女啪啪啪动态图| 国产高清有码在线观看视频| 中文字幕av成人在线电影| 国产综合懂色| av视频在线观看入口| 日韩av在线免费看完整版不卡| 精品人妻一区二区三区麻豆| 日本av手机在线免费观看| 日韩一本色道免费dvd| 观看免费一级毛片| 99国产精品一区二区蜜桃av| 久久久久久九九精品二区国产| 欧美3d第一页| 美女国产视频在线观看| 久久午夜福利片|