專題：Nature報導
以非常低的濃度檢測一個特定DNA序列的能力，在遺傳研究及診斷工作等應用中非常有價值。目前最好的技術需要對樣品進行放大和/或標記。在這項研究中，研究人員所採用的一個新方法能夠避免這樣的樣品準備步驟。該方法利用的是雜合型DNA和RNA分子的一個獨特機械性能，這種性能使它們能夠充當一種內在的分子標籤，從而在純樣品中能夠實現渺摩爾(10-18 M)級的檢測靈敏度。為了演示這種雜合方法在更偏向於生理研究方面的應用，研究人員用它來根據對腫瘤特異性微RNA的檢測進行腫瘤分類。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 462, 1075-1078 (24 December 2009) | doi:10.1038/nature08626
DNA nanomechanics allows direct digital detection of complementary DNA and microRNA targets
Sudhir Husale1, Henrik H. J. Persson2 & Ozgur Sahin1
1 The Rowland Institute at Harvard, Harvard University, Cambridge, Massachusetts 02142, USA
2 Stanford Genome Technology Center, 855 California Avenue, Palo Alto, California 94304, USA
Correspondence to: Ozgur Sahin1 Correspondence and requests for materials should be addressed to O.S.
Techniques to detect and quantify DNA and RNA molecules in biological samples have had a central role in genomics research1, 2, 3. Over the past decade, several techniques have been developed to improve detection performance and reduce the cost of genetic analysis4, 5, 6, 7, 8, 9, 10. In particular, significant advances in label-free methods have been reported11, 12, 13, 14, 15, 16, 17. Yet detection of DNA molecules at concentrations below the femtomolar level requires amplified detection schemes1, 8. Here we report a unique nanomechanical response of hybridized DNA and RNA molecules that serves as an intrinsic molecular label. Nanomechanical measurements on a microarray surface have sufficient background signal rejection to allow direct detection and counting of hybridized molecules. The digital response of the sensor provides a large dynamic range that is critical for gene expression profiling. We have measured differential expressions of microRNAs in tumour samples; such measurements have been shown to help discriminate between the tissue origins of metastatic tumours18. Two hundred picograms of total RNA is found to be sufficient for this analysis. In addition, the limit of detection in pure samples is found to be one attomolar. These results suggest that nanomechanical read-out of microarrays promises attomolar-level sensitivity and large dynamic range for the analysis of gene expression, while eliminating biochemical manipulations, amplification and labelling.