 |
 |
 |
 |
 |
 |
||
 |
 |
 |
 |
 |
| 3 | 1/1 | 返回列表 |
| 查看: 1386 | 回復: 2 | ||
| 本帖產(chǎn)生 1 個 翻譯EPI ，點擊這里進行查看 | ||
wo357026239銅蟲 (正式寫手)
|
[求助]
論文discussion翻譯
|
|
|
The strong two-photon luminescence of gold nanorods makes them suitable to 3D imaging. Although autofluorescence of cell provides the most convenient way for cell imaging, the high laser power of 35 mW needed to induce the autofluorescence is a potential safety hazard. As shown in Fig. 4A, cells can be killed after 30 raster scans at even a lower power of 30 mW. Obvious perforation of cells was observed when the power was increased to 35 mW (Fig. 6A). A laser operating at such a high power will thus cause clinical safety concerns. The enhanced imaging in the presence of gold nanorods is due to the high two-photon excitation cross section of gold nanorods, which is about ~3 ×104 GM for a nanorod with an aspect ration of 4 [31]. This is three orders of magnitude higher than that of a fluoresceine molecule [32,33]. Therefore, compared with the conventional fluorescent molecules, gold nanorod is a superior contrast agent. It was observed that membrane blebbing occurred on both necrotic and apoptotic cells. The initiation of cell membrane blebbing has been generally regarded as the sign of apoptosis [34]. During apoptosis, the cell’s cytoskeleton breaks up causing the membrane to bulge outward [35]. The intense femtosecond laser pulses particularly the localized photothermal effects of gold nanorods produced by the femtosecond laser pulses can destroy the intracellular actin network which provides mechanical support to maintain cell shape [7]. It was observed that the staining of the necrotic cells took only a few minutes. While for apoptotic cells to get sufficient staining with Annexin V-Cy3.18, the treated cells have to be incubated for at least 2 h. The short time required for PI staining of the necrotic cells indicates that the membrane of the cells was compromised. It was observed that when the laser power is 2mW(55.6 W/cm2) and above, perforation of cell membranewas induced after only one raster scan (Fig. 6B). The sharp decrease in irradiation duration can significantly reduce the energy fluence. However, a laser operating at this power presents a potential safetyhazard. This critical power/power density should be the upper limit that can be applied. With the eduction in the power density, the thermal effect becomes dominant and thermally induced cell damage controls the death of cells. Perforation of cell membrane enhanced in the presence of gold nanorods at high energy fluence was also reported in a real-time observation of a recent work. In terms of cancer therapy, significant reduction in the energy fluence can be achieved by inducing cell apoptosis rather than necrosis. For example, at 0.5 mW, apoptosis of HeLa cells was induced after being scanned 20 times, less than 1/7 of that needed to kill the cells (150 scans). When the laser power was increased to 1.5 mW, apoptosis of cells was induced after only 2 scans, which is only 1/5 of that required to induce necrosis. As a result, at a laser power ranging from 0.5 mW to 1.5 mW, the energy fluence for apoptosis is only about 1/7 to 1/5 (less than 20%) of that for necrosis, which is also two orders of magnitude lower than the medical safety level (100 mJ/cm2) [37]. The thresholds of energy fluence that cause cells necrosis and apoptosis at different laser powers are shown in Fig. 5. Increasing the laser power, the energy fluence for both necrosis and apoptosis was reduced. This can be attributable to the more intense heat production from the gold nanorods at a higher laser power. Apoptosis induction is important to medical applications since proliferation of cancer cells can be inhibited with low energy fluence. This will lead to the destruction of tumors in a safer and less aggressive manner, similar to drug-induced cell apoptosis and tumor damage in chemotherapy and radiotherapy. However, photothermally induced apoptosis can offer a more localized treatment and avoid the harsh side effects that are caused by anticancer drugs and radioactive isotopes. Interestingly, it was observed in a recent work that the photothermal effects of gold nanorods could induce apoptosis of macrophages by damaging the mitochondria [38], which regulates the apoptosis of cells. Whether this mechanism also governs the apoptosis of the cancer cells in this work is an interesting topic. |
回復此樓» 猜你喜歡
085600材料與化工調(diào)劑 324分
已經(jīng)有5人回復
-
344求調(diào)劑
已經(jīng)有6人回復
-
266求調(diào)劑
已經(jīng)有9人回復
-
化學工程321分求調(diào)劑
已經(jīng)有18人回復
-
314求調(diào)劑
已經(jīng)有8人回復
-
08工科 320總分 求調(diào)劑
已經(jīng)有5人回復
-
085601專碩，總分342求調(diào)劑，地區(qū)不限
已經(jīng)有5人回復
-
311求調(diào)劑
已經(jīng)有6人回復
-
化工學碩306求調(diào)劑
已經(jīng)有10人回復
-
286求調(diào)劑
已經(jīng)有8人回復
【答案】應(yīng)助回帖
wo357026239(金幣+120, 翻譯EPI+1): 2012-01-05 19:47:33
|
因其雙光子發(fā)光，金納米棒適用于三維成像。 盡管細胞的自發(fā)螢光提供了細胞成像的最簡單方法，其所需的用來激發(fā)自發(fā)光的高達35 毫瓦的激光能量為安全性帶來了潛在的威脅。如圖4A所示，即使激光能量低于30 毫瓦，30次光柵掃描后，細胞即可死亡。當能量被提高到35毫瓦時，可見明顯細胞穿孔 （圖6A）。 在如此高能量下的激光操作，將引起人們對醫(yī)療安全的擔憂。 加入金納米棒可改進成像，這是因為對一個長寬比為4的金納米棒來說，在其橫截面的雙光子激發(fā)可達約 ~3 ×104 GM，這比熒光素分子高出三個數(shù)量級［32，33］。因此，和傳統(tǒng)的熒光分子相比，金納米棒是優(yōu)秀的對比度提升劑。 在壞死的細胞和凋亡的細胞上皆可觀察到細胞膜起泡。細胞膜開始氣泡通常被認為是細胞凋亡的前兆［34］。 在細胞凋亡過程中，細胞骨架的破壞導致細胞膜向外鼓出。高強度的飛秒級激光脈沖，尤其是它所產(chǎn)生的金納米棒區(qū)域光熱效應(yīng)，可破壞提供支撐以維持細胞形狀的細胞間肌動蛋白網(wǎng)絡(luò)［7］�？梢杂^察到，壞死細胞的染色幾分鐘內(nèi)即可完成。使用Annexin V-cy3.18染色凋亡細胞，充分的染色需要至少2小時的培養(yǎng)。PI染色短時間內(nèi)即可完成，說明壞死細胞的膜已經(jīng)受到了損壞。當激光功率為2毫瓦或更高時，一次光柵掃描后即可觀察到細胞膜穿孔 （圖6B）。大幅度縮短輻照時間可明顯減少能量的注入。 然而，如此大功率的激光應(yīng)用，可帶來潛在的安全隱患。此功率／功率比應(yīng)為應(yīng)用中的最上限。當功率值下降時，熱效應(yīng)占據(jù)了主導地位，高溫導致的細胞損傷成為了細胞死亡的主要因素。在近期的工作中也有報導，實時觀測中可見在金納米棒的參與下，高功率輻照引起了更多的細胞穿孔。 在癌癥治療中，與細胞壞死相比，引發(fā)細胞凋亡可明顯降低所需的能量輸入。比如，在0.5毫瓦下，20次掃描即導致hela細胞凋亡，少于殺死細胞所需劑量的1/7 （150次掃描）。當激光功率提高到1.5毫伏，2次掃描即可導致細胞凋亡，這是導致細胞壞死所需的1/5。因此，當激光功率處于0.5 -1.5毫伏之間時，致使細胞凋亡所需的能量只是導致細胞壞死所需能量的1/7 到1/5（少于20％），同時也比醫(yī)療安全值 (100 mJ/cm2)低兩個數(shù)量級［37］。在不同激光功率下導致細胞壞死和凋亡的能量起始值如圖5所示。提高激光功率，致細胞壞死或凋亡的能量即隨之降低。這可歸因于更高激光功率下，金納米棒產(chǎn)生的熱量更高。 因為低能量的注入即可阻止癌細胞的繁殖，誘使細胞凋亡對醫(yī)療中的應(yīng)用非常重要。就像化學療法和和放射療法中，藥物所導致的細胞凋亡和腫瘤破壞一樣，這可以獲得一種更安全和平和的方式來破壞腫瘤。然而，光熱法治療所致的細胞凋亡可更精確的控于局部，避免了抗癌藥及用于輻照治療的同位素所帶來的強烈的副作用［38］。有趣的是，在近期的研究中，科學家們觀察到金納米棒的光熱效應(yīng)可通過破壞線粒體 （其控制細胞凋亡），導致巨噬細胞凋亡［38］。在本實驗中，是否這也是控制癌細胞凋亡的機理，仍是一個有趣的研究題目。 |
2樓2012-01-05 17:01:35
terry_well
榮譽版主 (知名作家)
笑熬漿糊——滿腦漿糊
- 翻譯EPI: 160
- 應(yīng)助: 207 (大學生)
- 貴賓: 1.508
- 金幣: 3769.8
- 散金: 9654
- 紅花: 229
- 沙發(fā): 11
- 帖子: 5857
- 在線: 601.1小時
- 蟲號: 352600
- 注冊: 2007-04-22
- 性別: GG
- 專業(yè): 燃燒學
- 管轄: 留學生活
【答案】應(yīng)助回帖
wo357026239(金幣+30): 2012-01-05 19:47:39
|
據(jù)觀察，膜出泡一般發(fā)生在壞死性和凋亡性細胞內(nèi)，并且細胞膜出泡已普遍被視為細胞凋亡的先兆[34]。在細胞凋亡過程中，細胞骨架的破壞造成了細胞膜向外凸出[35]。劇烈的飛秒激光脈沖作用下，尤其是金納米棒產(chǎn)生的局部飛秒激光脈沖導致的光熱效應(yīng)可以破壞細胞內(nèi)的肌動蛋白網(wǎng)絡(luò)，而該網(wǎng)絡(luò)它可以為維持細胞的形狀提供機械支持[7]。研究發(fā)現(xiàn)，只用幾分鐘即可破壞細胞的染色體。對凋亡的細胞來說，要采用Annexin V Cy3.18獲得足夠的染色處理，所處理的細胞至少需要培養(yǎng)2小時。若PI壞死細胞染色所需時間短則表明其細胞膜遭到了破壞。據(jù)觀察，當激光功率為2MW（55.6 W/cm2時）及以上時，一個光柵掃描誘導后細胞膜發(fā)生穿孔（如圖6B所示）。輻照持續(xù)時間大幅減少可以顯著降低能量密度。 然而，有人提出用這個功率的激光工作存在潛在的安全隱患。這個2MW的關(guān)鍵電源/功率密度可視為使用上限。隨著在功率密度降低，熱效應(yīng)成為主導，且熱誘導細胞損傷成為控制細胞死亡的只要因素。最新實時檢索表明，高能量通量的金納米棒可增強細胞膜穿孔的研究已經(jīng)報道。 在癌癥治療方面，顯著減少能源能量密度時，可通過誘導細胞凋亡而非使其壞死。例如，在0.5毫瓦時，掃描20次后可使HeLa癌細胞發(fā)生誘導凋亡，需要殺死的細胞不到1/7（150掃描）。當激光功率的增加1.5兆瓦，只有2掃描即可誘導癌細胞凋亡，此時誘發(fā)壞死的只有1 / 5。因此，激光功率范圍從0.5毫瓦到1.5兆瓦，為細胞凋亡的能源能量密度大約只有1 / 7至1 / 5（低于20％）為壞死，這也比醫(yī)療安全水平低兩個數(shù)量級（安全水平為100 mJ/cm2）[37]。圖5給出了在不同的激光功率下導致細胞壞死和凋亡的能量密度閾值。激光功率的增加會導致細胞壞死和凋亡的能量通量減少，這可以歸因于更高功率激光金納米棒所產(chǎn)生的更劇烈的熱效應(yīng)。 因為可以用低能量通量抑制癌細胞的擴散，誘導凋亡在醫(yī)療領(lǐng)域具有很重要的作用。這將獲得一個更安全、更有效地破壞腫瘤的治療方法。而類似的藥物誘導癌細胞凋亡可導致腫瘤化療和放療損傷。然而，輻照熱誘導細胞凋亡，可以提供更局部化處理并避免由抗癌藥物和放射性同位素引起的附帶影響。有趣的是，通過最近的工作觀察，金納米棒的光熱效應(yīng)通過破壞其線粒體可誘導巨噬細胞凋亡，從而調(diào)節(jié)細胞凋亡[38]。在這個作用機制是否也可以用來控制癌細胞凋亡將是一個有趣的課題。 太長了，僅供參考。  |
3樓2012-01-05 17:38:41
相關(guān)版塊跳轉(zhuǎn)
我要訂閱樓主 wo357026239 的主題更新
| 3 | 1/1 | 返回列表 |
| 最具人氣熱帖推薦 [查看全部] | 作者 | 回/看 | 最后發(fā)表 | |
|---|---|---|---|---|
|
[考研] 材料與化工一志愿南昌大學327求調(diào)劑推薦 +8 | Ncdx123456 2026-03-13 | 9/450 |
|
|---|---|---|---|---|
|
[考研] 298-一志愿中國農(nóng)業(yè)大學-求調(diào)劑 +7 | 手機用戶 2026-03-17 | 7/350 |
|
|
|
[考研] 0817 化學工程 299分求調(diào)劑 有科研經(jīng)歷 有二區(qū)文章 +7 | rare12345 2026-03-18 | 7/350 |
|
|
|
[考研] 0703化學調(diào)劑 ，六級已過，有科研經(jīng)歷 +10 | 曦熙兮 2026-03-15 | 10/500 |
|
|
|
[考研] 331求調(diào)劑（0703有機化學 +7 | ZY-05 2026-03-13 | 8/400 |
|
|
|
[考研] 307求調(diào)劑 +3 | 冷笙123 2026-03-17 | 3/150 |
|
|
|
[考研] 301求調(diào)劑 +9 | yy要上岸呀 2026-03-17 | 9/450 |
|
|
|
[考研] 293求調(diào)劑 +11 | zjl的號 2026-03-16 | 16/800 |
|
|
|
[考博] 26博士申請 +3 | 1042136743 2026-03-17 | 3/150 |
|
|
|
[考研] 267一志愿南京工業(yè)大學0817化工求調(diào)劑 +6 | SUICHILD 2026-03-12 | 6/300 |
|
|
|
[考研] 333求調(diào)劑 +3 | 文思客 2026-03-16 | 7/350 |
|
|
|
[考研] 304求調(diào)劑 +4 | ahbd 2026-03-14 | 4/200 |
|
|
|
[考研] 304求調(diào)劑 +3 | 曼殊2266 2026-03-14 | 3/150 |
|
|
|
[考研] 085600材料與化工 求調(diào)劑 +13 | enenenhui 2026-03-13 | 14/700 |
|
|
|
[考研] 0856專碩279求調(diào)劑 +5 | 加油加油！? 2026-03-15 | 5/250 |
|
|
|
[考研] 070305求調(diào)劑 +3 | mlpqaz03 2026-03-14 | 4/200 |
|
|
|
[考研] 297一志愿上交085600求調(diào)劑 +5 | 指尖八千里 2026-03-14 | 5/250 |
|
|
|
[考研] 招收0805（材料）調(diào)劑 +3 | 18595523086 2026-03-13 | 3/150 |
|
|
|
[考研] 求材料調(diào)劑 +5 | 隔壁陳先生 2026-03-12 | 5/250 |
|
|
|
[考研] 26調(diào)劑/材料科學與工程/總分295/求收留 +9 | 2026調(diào)劑俠 2026-03-12 | 9/450 |
|