A Pill to Find Diseases

Scientists have developed a small pill for patients to swallow. It mixes synthetic biology and electronics to find bleeding in the stomach and other parts of the digestive tract.

The biological part of the pill uses bacteria engineered to light up when it comes in contact with heme， the iron-containing molecule in blood. The electronic side includes a small light detector， computer and computer chip. It also has a battery to provide power and a transmitter that sends information to a cellphone or computer.

“A major challenge for sensing in the gastrointestinal tract is， the space available for a device is very limited，”said electrical engineer Phillip Nadeau. Nadeau and other engineers using very low-power electronics to make the pill. It measures about 3 centimeters long by 1 centimeter wide. The pill is still too big to swallow， but Nadeau says it likely can be engineered to a third that size.

The engineered bacteria are in areas covered by a membrane. This thin， soft material lets small molecules in， but does not let the organisms out. The researchers say the bacteria can be engineered to die if they accidentally leak from the pill. Future models may just use the most important enzymes instead of whole bacteria.

In lab tests， the pill successfully identified pigs fed small amounts of blood from those not given blood. The pill has not been tested on human beings， but the team hopes to do so in the next year or two.

Researchers believe that， once ready， the final product would sell for tens to hundreds of dollars. And they say the same method could be used to identify markers for disease or to find chemicals in the environment.

科學家開發出了一種讓病人吞服的小藥片。這種藥片是將合成生物學和電子學相結合而研制出來的，目的是發現胃內及消化道其他部位的出血。

藥片的生物學部分使用了一種基因工程菌，這種細菌接觸血液中含鐵的血紅素時會發光。藥片中的電子學部分包括一個小型光探測儀、計算機和計算機芯片，還有一塊電池提供動力，以及一個發送信息至手機或計算機的發射機。

“胃腸道傳感所面臨的主要挑戰是能夠容納一個設備的空間極其有限。”電氣工程師菲利普·納多說。納多和其他工程師使用非常小功率的電子設備來做這種藥片。藥片的尺寸大約三厘米長，一厘米寬。這藥片還是太大了，無法吞下。但是納多說有可能把藥片的尺寸縮小到原來的三分之一。

這種基因工程菌處于被一層薄膜覆蓋的區域。這種柔軟的薄材料可以讓小分子進來，卻不能讓生物體出去。研究者說，這種細菌可以通過基因工程而被改造為：如果它們意外地從藥片里逃出來，那么只有死路一條。未來的模型可能會僅使用重要的酶來代替完整的細菌。

實驗測試表明：這藥片能夠成功區分被喂過少量血液的豬和沒有被喂過血液的豬。目前，對藥片還沒有進行過人體試驗，但研究小組希望在未來的一兩年內用人體做試驗。

研究者認為，一旦一切就緒，最終產品的價格將在幾十美金到幾百美金。他們還說，可以使用同樣的辦法來識別疾病標記物或者發現環境中的化學物質。

（注意斜體句子的譯法）