Monday, August 31, 2009

Gold nanoparticles for lung cancer detection

Nature Nano published an article yesterday by Peng et al. (from Hossam Haick's group at Technion) claiming lung cancer detection by a breathe analyzer based on gold nanoparticles and the resistivity change upon contact with the patient's breathe.

Thin film of thiols with a monolayer of gold particles are wrapped into compartments that are called chemiresistors. The difference in the resistance to the applied current gives away if you have some of the characteristic volatile organic compounds (VOCs).

Truly a fascinating study. I hope it makes through the clinical trials.

For those who want to learn more here is the abstract:
Nature Nanotechnology
Published online: 30 August 2009 | doi:10.1038/nnano.2009.235

Diagnosing lung cancer in exhaled breath using gold nanoparticles

Gang Peng1,2, Ulrike Tisch1,2, Orna Adams1, Meggie Hakim1, Nisrean Shehada1, Yoav Y. Broza1, Salem Billan3, Roxolyana Abdah-Bortnyak3, Abraham Kuten3,4 & Hossam Haick1,2


Conventional diagnostic methods for lung cancer1, 2 are unsuitable for widespread screening2, 3 because they are expensive and occasionally miss tumours. Gas chromatography/mass spectrometry studies have shown that several volatile organic compounds, which normally appear at levels of 1–20 ppb in healthy human breath, are elevated to levels between 10 and 100 ppb in lung cancer patients4, 5, 6. Here we show that an array of sensors based on gold nanoparticles can rapidly distinguish the breath of lung cancer patients from the breath of healthy individuals in an atmosphere of high humidity. In combination with solid-phase microextraction7, gas chromatography/mass spectrometry was used to identify 42 volatile organic compounds that represent lung cancer biomarkers. Four of these were used to train and optimize the sensors, demonstrating good agreement between patient and simulated breath samples. Our results show that sensors based on gold nanoparticles could form the basis of an inexpensive and non-invasive diagnostic tool for lung cancer.

Lung cancer accounts for 28% of cancer-related deaths. Approximately 1.3 million people die worldwide every year1, 2. Breath testing is a fast, non-invasive diagnostic method that links specific volatile organic compounds (VOCs) in exhaled breath to medical conditions8, 9. Gas chromatography/mass spectrometry (GC-MS)4, 6, ion flow tube mass spectrometry10, laser absorption spectrometry11, infrared spectroscopy12, polymer-coated surface acoustic wave sensors5 and coated quartz crystal microbalance13 sensors have been used for this purpose. However, these techniques are expensive, slow, require complex instruments and, furthermore, require pre-concentration of the biomarkers (that is, treating the biomarkers by a process to increase the relative concentration of the biomarkers to a level that can be detected by the specific technique) to improve detection.

Here, we report a simple, inexpensive, portable sensing technology to distinguish the breath of lung cancer patients from healthy subjects without the need to pre-treat the exhaled breath in any way (see also refs 14–16 for the diagnosis of lung cancer by sensing technology that is based on arrays of polymer/carbon black sensors). Our study consisted of four phases and included volunteers aged 28–60 years. Samples were collected from 56 healthy controls and 40 lung cancer patients after clinical diagnosis using conventional methods and before chemotherapy or other treatment. The clinical characteristics of the volunteers are listed in Supplementary Tables S1 and S2.

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