根據一群德國科學家的最新研究指出，暴露在只有人類頭髮千分之一寬的奈米粒子下，會導致心跳速率改變，並且出現一般典型心臟疾病才會有的心律。
德國赫蒙霍玆慕尼黑衛生與環境研究中心(Helmholtz Zentrum München)和德國慕尼黑工業大學(Technische Universitaet München)的科學家們，利用稱為Langendorff心臟的系統，首次得以顯示奈米粒子對心臟會產生明顯可量測的效應。Langendorff心臟指的是一顆隔離體外的齧齒類動物心臟，以營養液沖灌來代替血液流動。
當暴露於一系列在藥品與工業常用的人造奈米粒子下的時候，這顆心臟對某些類型的粒子有了心跳速率增加、心律不整的症狀，經判讀心電圖的結果也與心臟疾病的指數相似。
德國慕尼黑工業大學水化學研究所主任涅斯納教授(Reinhard Niessner)解釋道，「我們把這顆心臟當成一種偵測器。這樣一來我們就可以測試某種特定的奈米粒子對心臟功能是否會產生效應。到目前為止還沒有任何人選擇用這樣的方式進行研究。」
這份研究在美國化學會(American Chemical Society)的期刊《ACS Nano》刊出， 研究的主筆史坦普(Andreas Stamfl)表示，「心臟作為測試目標的效果特別好。」
他表示，「心臟有自己的時間規律，有竇房結(sinus node，心跳週期的起始點)，所以心臟可以在體外持續以器官的形式運作長達數小時之久。」
史坦普跟他的團隊利用這個心臟模型系統測試碳黑(carbon black)，二氧化鈦(titamium dioxide)奈米粒子，以及引擎點火產生的碳(spark -generated carbon,用來代表從引擎燃燒柴油衍生的空氣汙染物)。
此外，二氧化矽(silicon dioxide)，在化粧品中作為增稠劑的各種不同氣膠二氧化矽，還有聚苯乙烯(polystyrene)也被用來測試。
碳黑、引擎點火產生的碳、二氧化鈦，以及二氧化矽都讓心跳速率增加了15%，並且導致心電圖呈現不正常的結果，即使停止奈米粒子暴露之後，還是無法恢復正常。
氣膠二氧化矽以及聚苯乙烯在實驗中對心臟功能並沒有產生任何效應。
涅斯納解釋道，「我們現在有一個絕佳的器官模式，可以用來測試人造奈米物質可能造成的影響。我們想要進行的下一步就是找出為什麼有些物質會影響心臟功能，有些卻完全不會。」
人造的奈米粒子在許多工業產品中受到廣泛的運用。舉例來說，二氧化鈦奈米粒子的表面積比較大，因此折射率比較高，可以讓這個物質看起來極度潔白。二氧化鈦奈米粒子常常被用在塗佈的白色漆料上，或用在防曬油中來阻擋紫外線。
碳黑是另一種受到廣泛使用的奈米粒子，主要是用在汽車輪胎以及塑膠製品中。每年全球的產量超過8百萬公噸。這些奈米粒子因為尺寸小，所以很適合用來作為印表機以及影印機的色料。
根據史坦普以及涅斯納指出，作為神經傳導物質的正腎上腺素(noradrenaline)很有可能是導致暴露在奈米粒子下心跳速率增加的因素。
正腎上腺素由心臟內壁的神經末梢釋出，它會增加心跳速率並且對中樞神經系統扮演重要的角色，這也指出奈米粒子可能也會對該處有損壞的效應。
藉助改良過的Langendorff心臟系統，研究人員終於首次開發出一套測量系統，用來分析奈米粒子對一個完整無缺的器官可能產生的效應，而不受其他器官的反應影響。
這套新的心臟模式也許可以對於醫學研究特別有用，在許多醫學研究中，人造奈米粒子越來越常被用來作為載體，運送活性藥劑(active agent)到人體內目的地，像是腫瘤。
大部分「奈米容器」的原型皆以碳或矽酸鹽作為基材。到目前為止，這些物質對人體可能會產生的效應仍多屬未知。研究人員表示他們的新型心臟模式也許可以作為選擇這些粒子種類的參考依據，避免這些用來進行醫療行為的物質對心臟有負面影響。
美國研究人員在2008年於美國心臟協會(American Heart Association)期刊《循環研究(Circulation Research)》發表的一份研究顯示，由車輛產生的奈米尺寸污染物可能會導致血小板在動脈堆積，造成人們心血管問題的風險。
這份研究的主筆，洛杉磯加州大學的環境心臟病學主任阿勞霍(Jesus Araujo)表示，這些污染物可能會藉由損害俗稱「好膽固醇」的保護機制，引起動脈硬化，阿勞霍表示，具有心臟疾病病史的人，應該對暴露在高濃度的污染物下特別小心。美國環保署並沒有針對環境中的奈米粒子進行管理規範，這些奈米粒子無法利用現有的科技捕捉收集。
Exposure to nanoparticles about one-thousandth the width of a human hair produces changes in heart rate and rhythm typical of heart disease, according to new research from a team of German scientists.
Using a so-called Langendorff heart - an isolated rodent heart flushed with a nutrient solution in place of blood - scientists from the Helmholtz Zentrum München and the Technische Universitaet München have, for the first time, been able to show that nanoparticles have a clearly measurable effect on the heart.
When exposed to a series of artificial nanoparticles commonly used in industry and medicine, the heart reacted to certain types of particles with an increased heart rate, cardiac arrhythmia and modified electrocardiogram values that are associated with heart disease.
"We use the heart as a detector," explained Professor Reinhard Niessner, director of the Institute of Hydrochemistry at the TU Muenchen. "In this way we can test whether specific nanoparticles have an effect on the heart function. Such an option did not exist hitherto."
"The heart is especially good as a test object," said Andreas Stampfl, first author of the study, reported in the journal "ACS Nano," a publication of the American Chemical Society.
"It has its own clock, the sinus node, and can therefore continue to work as an organ outside the body for several hours," he said.
Stampfl and his team used their heart model to test carbon black and titanium dioxide nanoparticles, as well as spark-generated carbon, which serves as a model for airborne pollutants stemming from diesel combustion.
In addition, silicon dioxide, different Aerosil silicas used as thickening agents in cosmetics, and polystyrene were tested.
Carbon black, spark-generated carbon, titanium dioxide and silicon dioxide led to an increase in the heart rate of up to 15 percent with altered electrocardiogram values that did not normalize, even after the nanoparticle exposure was ended.
The Aerosil silicas and polystyrene did not show any effect on the heart function.
"We now have a model for a superior organ that can be used to test the influence of artificial nanoparticles," Niessner explained. "The next thing we want to do is to find out why some nanoparticles influence the heart function, while others do not influence the heart at all."
Artificial nanoparticles are used in many industrial products. The relatively large surface area of titanium dioxide nanoparticles, for example, leads to a large refractive index that makes the substance appear brilliant white. It is often used in white coating paints or as a UV blocker in sunscreens.
Carbon black is another widely used nanoparticle, mainly in car tires and plastics, with over eight million tons produced annually. The small size of these nanoparticles makes them well suited for use as dyes in printers and copying machines.
According to Stampfl and Niessner, it is likely that the neurotransmitter noradrenaline is responsible for the increased heart rate brought on by nanoparticles.
Noradrenaline is released by nerve endings in the inner wall of the heart. It increases the heart rate and also plays an important role in the central nervous system - a tip-off that nanoparticles might also have a damaging effect there.
With their enhanced Langendorff heart, the researchers have now for the first time developed a measurement setup that can be used to analyze the effects of nanoparticles on a complete, intact organ without being influenced by the reactions of other organs.
This new heart model may prove to be particularly useful in medical research where artificial nanoparticles are increasingly deployed as transportation vehicles for active agents to a destination in the human body such as a tumor.
Most of the initial prototypes of such "nano containers" are carbon or silicate based. So far, the effect of these substances on the human body is largely unknown. The researchers say their new heart model could serve as a test organ to help select those particles types that do not affect the heart in a negative way.
Nano-size pollutants from vehicles can lead to plaque buildup in the arteries, putting people at risk of cardiovascular problems, American researchers said in a study published in 2008 in "Circulation Research," a journal of the American Heart Association.
The pollutants may cause arteries to harden by impairing the protective qualities of so-called good cholesterol, said Jesus Araujo, the study's lead author and director of environmental cardiology at University of California, Los Angeles.
Araujo said people with a history of heart disease should be especially cautious about being exposed to high levels of pollution. The U.S. Environmental Protection Agency does not regulate nanoparticles, which cannot be captured using current technology.
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