Sugar‑Coated Nanotube Sensor Distinguishes Mirror‑Image Molecules — A Step Toward Breath-Based Diagnostics

Researchers at the Hebrew University of Jerusalem have developed a gas sensor that can tell apart mirror‑image (chiral) molecules in air — a capability that could enable non‑invasive breath tests for diseases, improve food and fragrance quality control, and verify pharmaceutical purity.

The device combines carbon nanotubes with specially engineered sugar‑based receptor units that act like a molecular lock-and-key. The sugar receptors are chemically attached to the nanotubes so that when airborne molecules bind, tiny changes in electron flow through the nanotubes produce measurable electrical signals.

How the sensor works

The team designed a two‑part system: adjustable sugar frameworks linked to carbon nanomaterials. Each sugar receptor is tuned to favor one enantiomer (one “handed” form) of a target volatile compound. Even very weakly binding scent molecules produce distinct electrical responses because each mirror image interacts slightly differently with the receptor architecture.

Experimental results

Led by Ariel Shitrit and Yonatan Sukhran, under the supervision of Prof. Shlomo Yitzchaik and Prof. Mattan Hurevich, the researchers demonstrated clear discrimination between the two enantiomers of limonene and carvone, while the sensors showed no response to similar enantiomers of α‑pinene. The device detected (–)‑limonene down to about 1.5 parts per million, roughly ten times more sensitive than many standard techniques.

Electrical measurements were supported by computational simulations carried out in collaboration with the Technical University of Dresden and Friedrich Schiller University Jena. Those simulations helped explain how small differences in binding geometry change electron movement along the nanotubes and translate into distinct signals.

Challenges and engineering solutions

Converting water‑soluble sugar molecules into functional, stable gas‑phase receptors required overcoming chemical and engineering hurdles. The team solved this by chemically anchoring modular sugar units to carbon nanomaterials and tuning selectivity by modifying the sugar frame or the substituent groups attached to it.

Applications and next steps

Potential applications include:

• Non‑invasive breath diagnostics for conditions such as lung cancer or metabolic diseases
• Quality control in food, fragrance and beverage industries to ensure consistent aroma and detect spoilage
• Environmental monitoring for trace pollutants or chemical leaks
• Pharmaceutical verification of enantiomeric purity, where one mirror form may have different biological effects

The researchers expect that advanced physics simulations and machine learning will accelerate the design of new receptor chemistries and broaden the range of detectable chiral volatiles.

“By adding a sugar coating, we created a precise chemical architecture around the sensor that can even interact with very weakly binding scent molecules,” said Prof. Shlomo Yitzchaik. Prof. Mattan Hurevich added that the results provide “a blueprint for designing better artificial smell receptors.”

As the work progresses, miniaturization, arrayed sensors and computational pattern recognition could turn this approach into practical electronic ‘noses’ for medical, industrial and environmental use.