氧化钆纳米粒子对A549肺癌细胞的辐射增敏效应研究

采用氧化钆纳米粒子（GON）,研究钆基纳米粒子对X射线和碳离子束的辐射增敏效应。首先,通过透射电镜观察材料粒径,使用DLS检测材料的水合半径及Zeta电位,并用紫外吸收谱证实GON在培养基中稳定性较好;研究发现钆（Gd）浓度为10.0 μg/mL的GON对30 keV/μm碳离子束辐照水溶液产生的羟自由基的增强系数为1.13;GON对A549肺癌细胞和正常MRC-5肺细胞没有明显的毒性,且在人肺癌A549细胞中的摄取量随共培养浓度的增加而增加,在10.0 μg/mL共培养浓度下,细胞摄入Gd的量为0.73 pg/cell;进一步采用克隆存活实验证明,GON的加入对X射线和碳离子辐照A549细胞所产生的损伤具有明显的增强,在10%的细胞存活水平下,GON对A549细胞在X射线及碳离子辐照下的辐射增敏分别达15.5%和10.1%。鉴于钆材料常被用于磁共振成像（MRI）,所获得的GON有望作为X射线和碳离子的诊疗一体化材料。     

基于NASIC程序的纳米金辐射增敏效应模拟研究

纳米金粒子（GNP）应用为放疗辐射增敏剂是目前国际上的一个研究热点。使用自主研发的纳剂量生物物理蒙特卡罗程序(NASIC),模拟研究了光子照射下细胞环境中GNP的物理增敏效应和生物增敏效应。通过建立单个GNP位于细胞核中心以及多个GNP在细胞内四种理想分布的GNP-细胞模型,分析光子能量、GNP粒子尺寸和分布对能量沉积、DNA辐射损伤和细胞存活的影响。结果表明,GNP附近约2 m的范围内具有能量沉积的增强效应,这主要是因为GNP内光电效应作用数目的显著增加。不同条件下细胞核内能量沉积、DSB数目和细胞存活分数增强效应的变化规律基本一致,但增强因子呈递减趋势,三种评价指标增强因子的最大值分别为1.55,1.32 和1.14。光子能量为40 keV、GNP直径为100 nm并分布在细胞核表面时,相比其他参数组合具有较高的物理和生物辐射增敏效应。     

替拉扎明-金纳米粒子复合物对人肝癌HepG2细胞的辐射增敏效应研究

将替拉扎明(TPZ) 与聚乙二醇包被的金纳米粒子(PEG-GNP) 偶联,形成新型替拉扎明-金纳米粒子复合物(TPZ-PEG-GNP)。利用酶标仪获得TPZ-PEG-GNP 在200  800 nm范围内的紫外-可见光吸收光谱;采用电感耦合等离子体质谱(ICP-MS) 检测TPZ-PEG-GNP 在人肝癌HepG2 细胞中的摄取量;MTT法检测TPZ-PEG-GNP 对HepG2 细胞增殖活力的影响;香豆素-3-羧酸(3-CCA) 羟自由基探针检测X 射线和碳离子辐照下TPZ-PEG-GNP 在水中的羟自由基辐射增强效应;克隆形成法检测X 射线及碳离子辐照下TPZ-PEG-GNP 对HepG2 细胞的辐射增敏效应。实验结果表明:TPZ偶联到PEG-GNP 上形成的TPZPEG-GNP 对HepG2 细胞基本无毒;在有氧条件下,TPZ-PEG-GNP 在水中显著增加X射线和碳离子辐照下的羟自由基产额,对HepG2 细胞具有明显的辐射增敏效应;在X 射线及碳离子辐照下10% 存活水平时,TPZ-PEG-GNP 对HepG2 细胞的辐射增敏比分别为1.23 和1.47。

Tirapazamine (TPZ) was conjugated with polyethylene-glycol-coated gold nanoparticles (PEGGNP) to form new tirapazamine-gold nanoparticle compounds (TPZ-PEG-GNP). UV-vis absorption spectrum of TPZ-PEG-GNP at wavelengths from 200 to 800 nm was measured with a microplate reader. The kinetics
of TPZ-PEG-GNP uptake by human hepatoma  HepG2 cells was determined using inductively coupled plasma mass spectrometry (ICP-MS). To evaluate the cellular toxicity of TPZ-PEG-GNP, the effect of TPZ-PEG-GNP on HepG2 cell viability was examined by means of the MTT method. Moreover, the radiation enhancement effect of hydroxide radical production in ultra-pure water with TPZ-PEG-GNP exposed to X-rays and carbon ions was investigated using coumarin-3-carboxylic acid (3-CCA) as the free radical probe. More importantly, the radiosensitizing effect of TPZ-PEG-GNP on HepG2 cells irradiated with X-rays and carbon ions was assessed with the clonogenic survival assay. Our experimental results indicate that TPZ-PEG-GNP had nearly no toxicity to HepG2 cells. The yield of hydroxide radicals in ultra-pure water in the presence of TPZ-PEG-GNP after exposure to X-rays and carbon ions increased obviously and an obvious radiosensitizing effect of TPZ-PEG-GNP on HepG2 cells was observed under aerobic conditions. The radiation enhancement ratio of TPZ-PEG-GNP on HepG2 cells exposed to X-rays and carbon ions was 1.23 and 1.47 at 10% survival level.     

硫醇衍生化的纳米金与癌胚抗原相互作用的光学分析

纳米金已在在药物靶向传输体系、疾病检测、分子识别、生物标签等领域有着广泛的应用,但是,由于纳米金的表面效应,大量的表面原子具有巨大剩余成键能力,使得纳米金粒子较容易团聚、沉聚,影响了其稳定性。为了实现对肿瘤靶标之一-癌胚抗原的痕量检测,需要制备出对癌胚抗原检测具有良好的增色效应与荧光增敏效应的纳米材料。该工作采用纳米金的硫醇衍生法制备了一种新型的硫醇衍生化的纳米金材料,并对此新型硫醇衍生化的纳米金材料的特性用透射电子显微镜,紫外-可见吸收光谱,荧光发射光谱和红外光谱等方法进行了研究。紫外-可见吸收光谱,荧光发射光谱的实验结果表明,在新的配体乙二硫醇存在下,有更多的电子从配体的轨道跃迁到与中心离子相关的轨道上,导致荧光增强。这种新型硫醇衍生化的纳米金与癌胚抗原作用时表现出增色效应与荧光增敏效应,而纳米金与癌胚抗原作用时看不到这种增色效应与荧光增敏效应。红外方法的研究结果表明,这种材料的蛋白增色机理为当硫醇衍生化纳米金与癌胚抗原蛋白作用时,体系中蛋白的—OH表现出更多的面外弯曲振动,有利于电子从硫醇衍生化纳米金配合物向蛋白转移而导致其增色和荧光增敏效应。因而这种新的硫醇衍生化纳米金材料比纳米金将具有更好的生物检测应用价值。     

银纳米粒子的SERS效应和SEF效应在微流控芯片光学检测中的应用

银纳米离子的SERS技术和SEF技术的信号检测灵敏度非常高,可以用在微流控芯片的定量分析中。为了提高微流控芯片光学检测技术的检测精度,提出一种在微通道中添加银纳米粒子来增强SYBR GreenⅠ拉曼和荧光信号的方法,并对该方法的原理和增强效果进行了研究。首先,利用准分子激光器在PMMA基板上直写刻蚀出宽200 μm、深68 μm的微通道,接着将制备的银前体溶液加入微通道,通过加热制备出表面增强拉曼（SERS）和表面增强荧光（SEF）基板,接下来对添加银纳米粒子前后的拉曼和荧光信号分别进行对比,进一步研究了微通道中不同浓度银纳米粒子对SYBR GREEN I的拉曼和荧光信号增强效果。添加银纳米粒子后,表面增强拉曼（SERS）实验的增强因子为3.5×10³,添加银纳米粒子的样品的荧光信号强度与不含银纳米粒子样品的荧光信号强度相比,约增加了1倍。结果表明,在微通道中检测SYBR Green I时通过增加银纳米粒子显著地增强了拉曼和荧光信号,这种方法可以用在以SYBR GreenⅠ做染料的微流控芯片检测技术中。     

大蒜素在重离子放射治疗中的潜在用途

综述了大蒜素对正常细胞的保护机制和对肿瘤细胞的抑制机制, 并将其与辐射保护剂和辐射增敏剂的作用机制进行了比较, 提出大蒜素在放射治疗中对正常细胞具有辐射保护效应, 而对肿瘤细胞具有辐射增敏效应。 设想大蒜素的辐射保护和辐射增敏这种双重效应及其他优点在肿瘤放射治疗中能提高辐射生物学效应, 进一步改善治疗效果, 在临床应用中具有潜在的价值。 Garlic has beneficial effects to protect against many diseases. It can not only protect normal cells from lesion, but also prevent tumorigenesis, proliferation, adhesion, invasion and metastasis. In this paper, the mechanisms of these functions of garlic were summarized and compared with radioprotector and radiosensitizer. We presented that garlic has both radioprotective effect on normal cells and radiosensitive effect on tumor cells. By right of its superiority, garlic can improve biological effect in the therapy of heavy ion. Therefore, it has potential value in clinical practice. That is worth for us to explore whether garlic has radioprotective and radiosensitive effect or not.     

基于光热效应实现金纳米粒子的聚集及其SERS应用

为了实现金纳米粒子的高效聚集,获得高灵敏度的表面增强拉曼散射(SERS)基底,并研究激光对金纳米粒子的光热效应,搭建了一套集成像、SERS探测、光捕获为一体的光操控-显微拉曼系统,通过实验研究了光热效应对溶液中金纳米粒子的作用以及对待测物芘的SERS信号增强效应。此外,利用时域有限差分(FDTD)法从理论上计算了金纳米粒子聚集体与单个金纳米粒子的电场增强效果。结果表明:溶液中的金纳米粒子在热泳力及对流的共同作用下在石英衬底表面聚集,聚集速度受外界环境温度的影响;随着聚集时间延长,待测物芘的SERS信号强度增加,且其稳定后的SERS信号强度比金纳米溶胶基底增强了15倍;FDTD模拟结果表明金纳米粒子聚集体会产生比单个金纳米粒子更高的SERS增强因子,增强因子为1.30×10⁷。本研究利用光热效应实现了大范围、高效率捕获金纳米粒子的光操控,该方法可显著提高金纳米粒子的SERS效应,在化学和生物等领域的物质检测分析方面具有较大的应用潜力。     

和厚朴酚对非小细胞肺癌细胞的辐射增敏效应

研究了和厚朴酚（HNK）对非小细胞肺癌（NSCLC）细胞系A549和H1299对低线性能量转移（LET） X射线和高LET碳离子的辐射增敏效应。首先用CCK-8检测了HNK对A549和H1299细胞的生长抑制情况,发现20 μmol/L的HNK处理对细胞的生长抑制作用较弱。用该浓度HNK预处理细胞2 h后给予不同剂量X射线或碳离子的照射,克隆存活法检测细胞的辐射敏感性,Annexin-PI双染法检测细胞凋亡,γH2AX焦点法检测DNA的双链断裂（DSB）损伤。实验结果显示:与X射线相比,NSCLC细胞对碳离子更敏感,HNK预处理仅对碳离子照射有辐射增敏作用;与碳离子单独照射相比,HNK预处理联合碳离子照射诱导了更明显的细胞凋亡;在照射后24 h,HNK预处理联合碳离子照射引起的细胞γH2AX焦点阳性率维持在较高水平,而X射线照射没有这些效应。实验结果表明,HNK预处理抑制了NSCLC细胞DNA的DSB修复,诱导了细胞凋亡的发生,从而提高了细胞对碳离子的辐射敏感性。The radiosensitizing effect of Honokiol (HNK) on non-small cell lung carcinoma (NSCLC) cell lines A549 and H1299 to low-linear energy transfer (LET) X-rays and high-LET carbon ions was investigated in this study. First, the inhibitory effects of HNK on the growth of A549 and H1299 cells were detected by CCK-8 assay, and 20 μmol/L HNK treatment was found to induce a growth inhibitory effect slightly in these two cell lines. Cells were pre-treated with HNK and then irradiated with X-rays and carbon ions of different doses. Cellular radiosensitivity, apoptosis and DNA damage were analyzed by clonogenic survival, Annexin-PI staining and γH2AX foci, respectively. The results showed the cells were more sensitive to carbon ion irradiation compared to X-rays and the radiosensitization of HNK was only observed after carbon ion irradiation. Furthermore, the co-treatment led to higher apoptosis rate 48 h after irradiation and increased the positive rate of γH2AX foci 24 h after irradiation in A549 and H1299 cells compared with those in the groups treated with carbon ion irradiation alone. These phenomena were not observed after X-ray irradiation. Our data suggest that the pre-treatment with HNK inhibited DNA DSB repair, induced apoptosis and then enhanced the cellular radiosensitivity to carbon ions in NSCLC cells.     

纳米增强激光诱导击穿光谱的苹果表面农药残留检测

水果表面的农药残留严重危害身体健康,而常规检测方法需要采样处理,耗时、费力。激光诱导击穿光谱技术具有多元素分析和原位测量的能力,在水果表面农药残留检测方面潜力巨大。但是较差的检测灵敏度,限制了此技术在水果表面微量有害元素检测方面的应用。提高激光诱导击穿光谱系统的检测能力是目前的研究热点领域,研究了纳米粒子表面增强技术对苹果表面残留的毒死蜱农药的激光诱导击穿光谱信号的增强效果。通过在被测样品表面涂抹币族金属纳米粒子,然后利用激光诱导击穿光谱激发样品表面,对诱导出的原子发射光谱信号进行测量,实验结果表明,苹果表面涂抹金属纳米粒子后毒死蜱农药中磷元素的特征峰有4倍的增强。此方法的应用对提高果蔬表面微量有害元素的检测能力具有重要意义。然后我们对币族金属纳米粒子的增强效果进行了优化。研究了金纳米粒子和银纳米粒子的增强能力,同时对纳米粒子的粒径的增强效果进行了比较,通过对20 nm的金纳米粒子、20 nm的银纳米粒子和80 nm的银纳米粒子的增强效果比较,发现80 nm的银纳米粒子对苹果表面毒死蜱农药光谱的增强效果最好。研究了信号采集延时时间对光谱信噪比的影响,确定了0.2 μs的延时时间可以获得较为理想的信噪比。在以上研究的基础上,采用最优的实验参数(80 nm银粒子增强、0.2 μs的延时时间),以毒死蜱中磷元素在213.62,214.91,253.56和255.33 nm处的特征峰峰强作为依据,对苹果表面残留的毒死蜱农药进行了定量化分析。分别采集了毒死蜱残留浓度分别为30,20,15,12,10和6 μg·cm-2的苹果表面的LIBS光谱,然后分别利用磷元素的四个特征峰峰强进行了定量化曲线拟合,结果发现LIBS对残留的毒死蜱具有很好的定量化预测能力,R2在0.89以上。根据定量化拟合曲线,探讨了纳米增强LIBS的检测限,计算得到,利用纳米增强LIBS技术测量苹果表面的毒死蜱农药最低可以做到1.61 μg·cm-2的检测限。研究证明了金属纳米粒显著提高了LIBS对苹果表面农药残留的检测灵敏度。     

新型冠状病毒S蛋白在金纳米粒子中的表面增强拉曼效应

表面增强拉曼光谱技术因其高灵敏度、操作简单、快速检测等优点,被广泛用于病毒检测方面。国内外的病毒拉曼检测研究主要集中在检测病毒核酸以及组成核酸的各种碱基的表面增强拉曼光谱(SERS),但少见对病毒蛋白的SERS检测。以新型冠状病毒（SARS-CoV-2）的S蛋白为检测对象,采用无标记SERS检测方法,对比SARS-CoV-2固态、饱和液态S蛋白的普通拉曼光谱和选用40 nm金纳米粒子为基底的SARS-CoV-2低浓度S蛋白SERS光谱。结果表明,以40 nm金纳米粒子为基底,采用SERS技术检测SARS-CoV-2的S蛋白是完全可行的。SARS-CoV-2的S蛋白分子中的羧基与金纳米粒子发生了分子增强,氨基与金纳米粒子发生了电磁增强,从而使得SARS-CoV-2的S蛋白拉曼效应得到了增强,并使得峰位发生一定移动。实验获得了较好的SARS-CoV-2低浓度S蛋白SERS光谱,为建立敏感、特异、快速的SARS-CoV-2检测新技术提供了一种方法。     

羧甲基-β-1,3-葡聚糖对人肝癌HepG2细胞的放射增敏作用

本研究旨在探讨羧甲基-β-1,3葡聚糖（CMG）对人肝癌HepG2细胞X射线或12C6+离子束辐射敏感性的影响。首先用CCK-8法检测CMG对HepG2细胞的生长抑制情况,得到半数抑制浓度（IC50）为120.6μg/mL。用浓度为0.1×IC50的CMG预处理HepG2细胞24 h,再给予2 Gy X射线或12C6+离子束辐照（CMG+辐照组）;CMG未处理组直接接受2 Gy X射线或12C6+离子束辐照（辐照组）。对比分析辐照组和CMG+辐照组细胞的克隆存活、DNA损伤、凋亡与周期分布、细胞内活性氧（ROS）水平。发现:与X射线辐照组相比,相同剂量的12C6+离子辐照组克隆存活率更小,DNA损伤和周期阻滞更加严重,细胞凋亡率和细胞内ROS水平也更高。与单独X射线或12C6+离子束辐照组相比,CMG+辐照组克隆存活率明显降低,细胞凋亡率随辐照后CMG作用时间的延长而明显增加,CMG使辐照后细胞内ROS维持在一个较高的水平,同时CMG明显加重了单独辐照诱导的DNA损伤和周期阻滞。结果表明,与X射线相比,HepG2细胞对相同剂量的12C6+离子辐射更敏感;CMG可增加HepG2细胞对X射线或12C6+离子辐射的敏感性;CMG可能通过增加受照HepG2细胞内的ROS水平,加剧辐照诱导的DNA损伤,促进辐射诱导细胞凋亡而起到辐射增敏作用。This study aims to investigate the effect of carboxymethy-β-1, 3-glucan (CMG) on the sensitivity of human hepatoma HepG2 cells to X-rays or 12C6+ ions irradiation. First, the inhibitory effect of CMG on the growth of HepG2 cells was detected by CCK-8 assay, and the half maximal inhibitory concentration (IC50) was 120.6 μg/mL. HepG2 cells were pretreated with CMG at a concentration of 0.1×IC50 for 24 h and then irradiated with 2 Gy X-ray or 12C6+ ion beams (CMG + irradiation group). CMG untreated group was directly irradiated by 2 Gy X-rays or 12C6+ ions beam (irradiation group). The clone survival, DNA damage, cell apoptosis, cell cycle distribution, and intracellular reactive oxygen species (ROS) levels in irradiation group and CMG + irradiation group were comparatively analyzed. The results showed that the clone survival rate was lower, DNA damage and cycle arrest were more serious, and the rate of apoptosis and intracellular ROS levels were higher in 12C6+ ions irradiation group than those in the same dose of X-rays irradiation group. Compared with X-rays or 12C6+ ions irradiation group, the clone survival rate of CMG + irradiation group was significantly decreased, and the apoptosis rate significantly increased with the prolongation of CMG treatment post-irradiation; CMG maintained intracellular ROS at a higher level after irradiation, CMG also significantly aggravated radiation-induced DNA damage and cycle arrest. These results indicated that HepG2 cells were more sensitive to 12C6+ ions radiation than those at the same dose of X-rays. CMG increased the sensitivity of HepG2 cells to X-rays or 12C6+ ions irradiation by increasing intracellular ROS level, exacerbating radiation-induced DNA damage and promoting radiation-induced apoptosis in irradiated HepG2 cells.     

Fluorescence imaging of reactive oxygen species by confocal laser scanning microscopy for track analysis of synchrotron X‐ray photoelectric nanoradiator dose: X‐ray pump–optical probe

Bursts of emissions of low‐energy electrons, including interatomic Coulomb decay electrons and Auger electrons (0–1000 eV), as well as X‐ray fluorescence produced by irradiation of large‐Z element nanoparticles by either X‐ray photons or high‐energy ion beams, is referred to as the nanoradiator effect. In therapeutic applications, this effect can damage pathological tissues that selectively take up the nanoparticles. Herein, a new nanoradiator dosimetry method is presented that uses probes for reactive oxygen species (ROS) incorporated into three‐dimensional gels, on which macrophages containing iron oxide nanoparticles (IONs) are attached. This method, together with site‐specific irradiation of the intracellular nanoparticles from a microbeam of polychromatic synchrotron X‐rays (5–14 keV), measures the range and distribution of OH radicals produced by X‐ray emission or superoxide anions () produced by low‐energy electrons. The measurements are based on confocal laser scanning of the fluorescence of the hydroxyl radical probe 2‐[6‐(4′‐amino)phenoxy‐3H‐xanthen‐3‐on‐9‐yl] benzoic acid (APF) or the superoxide probe hydroethidine‐dihydroethidium (DHE) that was oxidized by each ROS, enabling tracking of the radiation dose emitted by the nanoradiator. In the range 70 µm below the irradiated cell, radicals derived mostly from either incident X‐ray or X‐ray fluorescence of ION nanoradiators are distributed along the line of depth direction in ROS gel. In contrast, derived from secondary electron or low‐energy electron emission by ION nanoradiators are scattered over the ROS gel. ROS fluorescence due to the ION nanoradiators was observed continuously to a depth of 1.5 mm for both oxidized APF and oxidized DHE with relatively large intensity compared with the fluorescence caused by the ROS produced solely by incident primary X‐rays, which was limited to a depth of 600 µm, suggesting dose enhancement as well as more penetration by nanoradiators. In conclusion, the combined use of a synchrotron X‐ray microbeam‐irradiated three‐dimensional ROS gel and confocal laser scanning fluorescence microscopy provides a simple dosimetry method for track analysis of X‐ray photoelectric nanoradiator radiation, suggesting extensive cellular damage with dose‐enhancement beyond a single cell containing IONs.     

重离子辐射提高腺病毒介导小鼠黑色素瘤细胞转染率的研究

探讨12C6+ 离子束辐射对用带有绿色荧光蛋白基因的缺陷性腺病毒（AdCMV GFP）转染小鼠黑色素瘤细胞(B16细胞系)的影响。 采用不同剂量的12C6+ 重离子束辐射经AdCMV GFP 转染的B16细胞， 利用流式细胞仪检测腺病毒的转染率。 结果表明， 12C6＋重离子束辐射能提高腺病毒对B16细胞的转染率， 且具有量效关系。 此外， 先转染后辐射法比起先辐射后转染法能更显著地提高转染率。The effect of 12C6+ beam irradiation on AdCMV GFP (a replication deficient recombinant adenoviral vector containing CMV promoter and green fluorescent protein) gene transfection efficiency for murine melanoma cell B16 has been investigated. B16 cells infected with AdCMV GFP were irradiated by different doses of 12C6+ beam. The transfection efficiency was assessed by flow cytometry (FCM). Results show that 12C6+ beam irradiation can improve tansfection efficiency of AdCMV GFP on murine melanoma cell B16 in a dose dependent manner. In addition， the tansfection efficiency in pre tranfection plus irradiation group is higher than that in pre irradiation plus tranfection group at the same dose irradiation dose.     

ROS enhancement by silicon nanoparticles in X-ray irradiated aqueous suspensions and in glioma C6 cells

The capability of silicon nanoparticles to increase the yield of reactive species upon 4 MeV X-ray irradiation of aqueous suspensions and C6 glioma cell cultures was investigated. ROS generation was detected and quantified using several specific probes. The particles were characterized by FTIR, XPS, TEM, DLS, luminescence, and adsorption spectroscopy before and after irradiation to evaluate the effect of high energy radiation on their structure. The total concentration of O₂ ^•−/HO₂ ^•, HO^•, and H₂O₂ generated upon 4-MeV X-ray irradiation of 6.4 μM silicon nanoparticle aqueous suspensions were on the order of 10 μM per Gy, ten times higher than that obtained in similar experiments but in the absence of particles. Cytotoxic ¹O₂ was generated only in irradiation experiments containing the particles. The particle surface became oxidized to SiO₂ and the luminescence yield reduced with the irradiation dose. Changes in the surface morphology did not affect, within the experimental error, the yields of ROS generated per Gy. X-ray irradiation of glioma C6 cell cultures with incorporated silicon nanoparticles showed a marked production of ROS proportional to the radiation dose received. In the absence of nanoparticles, the cells showed no irradiation-enhanced ROS generation. The obtained results indicate that silicon nanoparticles of <5 nm size have the potential to be used as radiosensitizers for improving the outcomes of cancer radiotherapy. Their capability of producing ¹O₂ upon X-ray irradiation opens novel approaches in the design of therapy strategies.     

Photoinduced toxicity of PrF<Subscript>3</Subscript> and LaF<Subscript>3</Subscript> nanoparticles

PrF₃ and LaF₃ nanoparticles were synthesized by the hydrothermal method. The size distribution of these nanoparticles in the colloidal solution produced was studied by photon correlation spectroscopy. The mean diameter of the nanoparticles was 42 ± 1 nm. During the study of the toxicity of the nanoparticles, the mixture of a colloidal solution of the nanoparticles with cells to be studied was irradiated by 30-mW continuous lasers at wavelengths of 532 and 473 nm. The concentration of salmonella cells in normal saline was 10⁶ cell/mL, while that of nanoparticles was 0.1 g/L. The cell survival percentage was 39, 34, and 20% for the irradiation times of 5, 10, and 15 min, respectively, at an optimal laser radiation power density of 0.4 W/cm at a wavelength of 532 nm. It was ascertained that LaF₃ nanoparticles do not possess the property of photoinduced toxicity and the apoptosing effect. Moreover, the property of photoinduced toxicity is not shared by microparticles, in contrast to nanoparticles.     

Paramagnetic centers in tumor cells

Free radical properties of different types of tumor cells were compared. Electron paramagnetic resonance (EPR) studies were performed for human (BM, IGR and SK) and mouse (B16 and S91) melanoma cells. In contrast to melanotic melanoma IGR, BM and B16 cells, amelanotic S91 cells contained only a trace amount of melanin. No EPR signals were detected for Caco2 cells and only a very weak EPR line was measured for fibroblast cells. Melanin does not exist in these cells. The aim of this work was the application of EPR spectroscopy to the determination of the kind of melanin (eu- or pheomelanin) in melanotic tumor cells. Microwave saturation of EPR spectra of tumor cells with high and low melanin content was compared. Eumelanin was identified in human BM, IGR, SK, and B16 melanoma cells. Single asymmetrical EPR lines were detected for these samples. The EPR spectra of human BM melanoma cells had the highest intensity. Paramagnetic centers in amelanotic S91 melanoma cells were also found. Trace amounts of eumelanin free radicals and the other free radicals in cells were responsible for their very weak EPR lines. The obtained results indicate that EPR spectroscopy is a very useful technique for the identification of melanin in tumor cells. Strong differences of microwave saturation of EPR lines for cells with high and low melanin content were observed. EPR lines of tumor cells with a low melanin content did not saturate at the used range of microwave power. Saturation was observed for melanotic BM melanoma cells.     

Sensitizer localization and immune response in photodynamic therapy of B16 cells

This paper proposes to extend the exploration of mouse melanoma B16 cells death by photodynamic therapy (PDT), under irradiation with different light sources and in the presence of 5,10,15,20-tetrap-sulphonato-phenyl-porphyrin (TSPP). The viability studies showed that B16 mouse melanoma is sensitive to photodynamic damage induced by TSPP 1 mM for either one, two, three or four hours. The control had TSPP added immediately prior to timelapse imaging (no incubation). They were then irradiated with red light He-Ne laser (λ = 632.8 nm, energy 180 J/cm² for 20 min). Also, it has been used a laser diode GaInAs 25 mW/cm², λ = 650 nm. The cells demonstrated clear morphological changes associated with apoptosis by mitochondrial pathway. There were changes in texture, as expected. Changes appeared to occur more quickly at lamp irradiation than at HeNe and GaInAs diode laser. Addition of TSPP just prior to exposure and observation, with no incubation, did not result in changes in cell morphology or cell death. Also, the proteins changes have been observed, because those with high molecular weights have been scissored under irradiation and this could be reason of the proteins concentrating in the area of low molecular weights, and the dissapearing of the proteic band of 75 kDa in the electrophoregramm. The immunized animals with B16-TSPP had the highest survival rate (40 days) by comparison with the control (death at 20 days) or with immunized animals with supernatants B16 (death at 25 days).     

Silica nanoparticles induce multinucleation through activation of PI3K/Akt/GSK-3β pathway and downregulation of chromosomal passenger proteins in L-02 cells

Silica nanoparticles (SNPs) are applicable in various fields due to their unique physicochemical characteristics. However, concerns over their potential adverse effects have been raised. In our previous studies, we reported that SNPs could induce abnormal high incidence of multinucleation. The aim of this study is to further investigate the mechanisms of multinucleation induced by SNPs (68 nm) in human normal liver L-02 cells (L-02 cells). In order to determine the cytotoxicity of SNPs, MTT assay was performed, and the cell viability was decreased in a dose-dependent manner. The intracellular reactive oxygen species (ROS) detected by flow cytometry and multinucleation observed by Giemsa stain showed that ROS generation and rate of multinucleated cells increased after SNPs exposure. N-acetyl-cysteine (NAC), a glutathione precursor against SNP-induced toxicity, was used as a ROS inhibitor to elucidate the relationship between ROS and multinucleation. The presence of NAC resulted in inhibition of both ROS generation and rate of multinucleation. Moreover, Western blot analysis showed that the protein levels of Cdc20, Aurora B, and Survivin were down-regulated, and the PI3K/Akt/GSK-3β pathway was activated by SNPs. In conclusion, our findings strongly suggested that multinucleation induced by SNPs was related to PI3K/Akt/GSK-3β signal pathway activation and downregulation of G2/M phase-related protein and chromosomal passenger proteins.     

Cytotoxic and radiosensitizing effects of nano-C<Subscript>60 </Subscript>on tumor cells in vitro

There is growing evidence in recent years that the pristine fullerene may be endowed with strong pro-oxidant capacity to biological samples. In this investigation we tested the hypothesis that water-soluble fullerene-C₆₀ (nano-C₆₀) may interact with ionizing radiation enhancing its antiproliferative effects. The two tumor cell lines with different radiosensitivity B16 and SMMU-7721 were treated by a combination of pristine fullerene and ⁶⁰Co γ irradiation. We measured cell survival rates, apoptotic characteristics, reactive oxygen species (ROS) production and alteration of cell diameter with or without γ-irradiation. There was reduced survival with B16 and SMMU-7721 cells exposed to nano-C₆₀, with the inhibitory concentrations reducing the viability by 50% to 65 part per billion (ppb) and 150 ppb respectively. For cells exposed to nano-C₆₀ prior to γ-irradiation, damage to cell membranes and increased numbers of apoptotic cells were detected by morphologic Hoechst-staining analysis and Annexin V/propidium iodide double-staining. In cells exposed to nano-C₆₀, there were increased levels of ROS, as measured by fluorescence detection under laser confocal microscopy. Preincubation with non-toxic pristine C₆₀ before γ-ray caused enlargement of cells with increased diameter. The results show that nano-C₆₀ inhibits the growth of tumor cells at certain concentrations and increases the effects of ⁶⁰Co γ-irradiation, possibly through the elevated production of cellular ROS and the membrane disruption. Data in this study indicates a possible consideration of using C₆₀ as a candidate of sensitization modifier in tumor radiation biology.