Olfactory Detection of Toluene by Detection Rats for Potential Screening of Lung Cancer

Abstract

Early detection is critical to successfully eradicating a variety of cancers, so the development of a new cancer primary screening system is essential. Herein, we report an animal nose sensor system for the potential primary screening of lung cancer. To establish this, we developed an odor discrimination training device based on operant conditioning paradigms for detection of toluene, an odor indicator component of lung cancer. The rats (N = 15) were trained to jump onto a floating ledge in response to toluene-spiked breath samples. Twelve rats among 15 trained rats reached performance criterion in 12 consecutive successful tests within a given set, or over 12 sets, with a success rate of over 90%. Through a total of 1934 tests, the trained rats (N = 3) showed excellent performance for toluene detection with 82% accuracy, 83% sensitivity, 81% specificity, 80% positive predictive value (PPV) and 83% negative predictive value (NPV). The animals also acquired considerable performance for odor discrimination even in rigorous tests, validating odor specificity. Since environmental and long-term stability are important factors that can influence the sensing results, the performance of the trained rats was studied under specified temperature (20, 25, and 30 °C) and humidity (30%, 45%, and 60% RH) conditions, and monitored over a period of 45 days. At given conditions of temperature and humidity, the animal sensors showed an average accuracy within a deviation range of ±10%, indicating the excellent environmental stability of the detection rats. Surprisingly, the trained rats did not differ in retention of last odor discrimination when tested 45 days after training, denoting that the rats’ memory for trained odor is still available over a long period of time. When taken together, these results indicate that our odor discrimination training system can be useful for non-invasive breath testing and potential primary screening of lung cancer.

Disease Diagnosis with Chemosensing, Artificial Intelligence, and Prospective Contributions of Nanoarchitectonics

“…Consequently, the downstream products, including VOC profiles, are putatively distinguishable by more advanced olfactory systems. In the past decade, attempts have been made to harness fruit fly [109,110], canine [111,112], and murine [113] olfactory systems for cancer detection. In the absence of comparable artificial gas sensors, biological sensors have demonstrated the potential for chemosensing in the detection of cancer, but they also demonstrate inherent flaws such as ethical controversy, investment into training and sustaining animals, errors in interpreting animal behavior, lacking robustness and quantifiability, and being unsuitable for storage.…”

Hydrogen Biosensing: Prospects, Parallels, and Challenges

“…Sensitive detection of up to 20 ppb of acetone was achieved using a fiber-optic biochemical gas-sensing system by the reversible action of the enzyme NADH-dependent secondary alcohol dehydrogenase through the utilization of an ultraviolet light-emitting diode (UV-LED) lamp of a specific wavelength (335 nm) (Table , entry 4). Similarly, the levels of hydrogen sulfide, ammonia, nitric oxide, and toluene aid in the diagnosis of halitosis, kidney malfunction, − asthma, and lung cancer respectively. The biosensor for halitosis was based on monoamine oxidase type-A enzyme being immobilized on the tip of the electrode.…”

Pancreatic Cancer and Detection Methods

“…While e-nose sensors aim to mimic the animal olfactory system and have limitations in odor selectivity and development time. Actual animal sensors have an advantage due to their natural olfactory networks, capable of discerning various metabolic profiles of normal and abnormal cells thereby yielding different metabolites [ 199 ]. Living organisms, particularly dogs known for their remarkable olfactory acuity, have been used to detect diseases, including cancer [ 200 ].…”