# Istanbul Technical University creates NIR-2 sensor that detects mercury(II) ions in 10 seconds, tested in the lab

- Published: 2026-11-12 19:24 UTC
- Section: Science › Instruments & experiments
- Tags: mercury sensor, mercury(II) detection, near-infrared fluorescent probe, selenium chemosensor, smartphone colorimetric detection, heavy metal pollution, Istanbul Technical University, NIR-2
- URL: https://realtech.media/news/rt-00450b3396d3ef4d815e4955_istanbul_technical_university/

**The NIR-2 molecule changes color and emits near-infrared light in the presence of mercury(II). In laboratory tests a smartphone camera read the signal, but the sensor is not yet a ready-to-use detector.**

![Istanbul Technical University creates NIR-2 sensor that detects mercury(II) ions in 10 seconds, tested in the lab](https://realtech.media/media/2026/11/9687260df12b2a6f.jpg)
*NASA Johnson Space Center, Wikimedia Commons, Public domain*

Researchers at Istanbul Technical University (ITU) have created a molecular sensor, NIR-2, that responds to mercury(II) ions by changing color and emitting near-infrared light, according to a release published by EurekAlert on 10 November 2026 [1]. The study appeared in Talanta and was carried out by researchers from ITU and Recep Tayyip Erdoğan University [1]. The sensor responded in about 10 seconds, and the signal remained stable for at least 20 minutes [1].

## How the selenium switch works

At the core of NIR-2 is a selenium-based molecule that is normally in a closed form and emits minimal light. Mercury(II) ions strongly attract selenium, and on contact they open the structure [1]. The solution then changes from yellow to green and emits intense near-infrared light [1]. The same reaction therefore produces both a visible color change and a fluorescent signal. The color can be seen directly or captured with a camera, while the near-infrared signal can be read with laboratory instruments and used for cellular imaging [1].

UV–visible spectroscopy detected mercury(II) at concentrations as low as 3.77 × 10⁻¹⁰ M, and fluorescence measurements reached 4.54 × 10⁻⁹ M [1].

## Smartphone readout and test samples

The team also photographed samples with a Redmi Note 10S and analyzed the red and green color components. Using the ratio of these colors reduced the effect of lighting variations [1]. The smartphone method detected Hg²⁺ from 1.66 × 10⁻⁹ to 7.50 × 10⁻⁶ M, which the authors consider the most sensitive smartphone-based Hg²⁺ detection range reported so far [1]. The U.S. EPA maximum contaminant level for inorganic mercury in drinking water is 2 parts per billion, or 0.002 mg/L, and the lower limit of the smartphone approach falls below it under controlled experimental conditions [1].

The researchers tested drinking, tap and lake water, as well as strawberries, watermelon and cherries, all intentionally spiked with known amounts of mercury [1]. In rice, corn, beans and lentils the sensor gave semi-quantitative color responses in several cases, but its effectiveness varied with the food matrix [1]. In three human lung cell lines, cell viability stayed above 90%, and fluorescence imaging showed a mercury-dependent signal inside the cells [1].

The authors note that the results do not yet make NIR-2 a ready-to-use consumer detector. Sample preparation was still required, measurements were taken under controlled lighting, and most experiments used samples with mercury added by the researchers [1]. Testing with naturally contaminated samples, varied environmental conditions and field measurement systems is still needed [1]. The researchers also propose that the molecular design could serve as a basis for sensors for other substances [1].

## Sources

1. [EurekAlert](https://www.eurekalert.org/news-releases/1151211)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-00450b3396d3ef4d815e4955_istanbul_technical_university/