Aloe vera carbon dots detect temperature, pH, and iron levels

Greg Howard
23rd January, 2026

Aloe vera carbon dots detect temperature, pH, and iron levels

Higher synthesis temperatures yield smaller, more spherical carbon dots derived from Aloe vera (a–c), while longer reaction times at 240°C initially increase particle size (d, e) before a reduction occurs (f), illustrating the precise morphological control that is key to optimizing the nanoparticles' sensing capabilities.

Image adapted from: Rezk et al. / CC BY (Source)

Key Findings

  • Researchers developed a sustainable method to create carbon dots (CDs) from Aloe vera gel using a simple hydrothermal process
  • CDs synthesized at 240°C for 12 hours exhibited the brightest fluorescence and were selected for further testing as sensors
  • These optimized CDs effectively detect temperature changes and iron(III) ions (Fe³⁺) with high sensitivity, showing potential for environmental monitoring and biomedical applications
Carbon dots (CDs) are emerging as versatile materials with applications in sensing and bioimaging due to their unique optical properties and biocompatibility. Recent research from Tanta University and Kafrelsheikh University[1] details a new method for creating these CDs using Aloe vera gel as a sustainable starting material, offering a ‘green’ alternative to traditional synthesis routes. This work focuses on optimizing the production process to achieve the brightest and most sensitive CDs possible. The challenge in utilizing CDs effectively lies in controlling their properties. The size, shape, and surface chemistry of CDs significantly impact their ability to fluoresce – emit light when exposed to a specific wavelength. The research team addressed this by carefully adjusting the conditions during the hydrothermal synthesis, a process involving heating a solution in a sealed container. Specifically, they varied the reaction temperature (180-240°C) and duration (4-16 hours) to determine the ideal combination for CD production. Hydrothermal synthesis is already known as an effective method for creating CDs, particularly when incorporating heteroatoms like nitrogen and sulphur to enhance their properties[2]. The team used cysteine and urea in a similar process to create biocompatible, photoluminescent carbon dots, demonstrating their potential for cancer cell imaging. The current study builds on this by utilizing a completely natural precursor – Aloe vera gel – and systematically optimizing the synthesis parameters. Characterizing the resulting CDs involved several techniques. UV-Vis spectroscopy confirmed the absorption properties of the dots, while photoluminescence spectroscopy measured their emission characteristics. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to determine the structure and shape of the CDs, revealing they were uniformly dispersed and amorphous. Fourier transform infrared (FTIR) spectroscopy identified the functional groups present on the surface, which are crucial for their sensing capabilities. The optimization process revealed that CDs synthesized at 240°C for 12 hours exhibited the highest photoluminescence quantum yield (PLQY). PLQY is a measure of how efficiently the CDs convert absorbed light into emitted light – a higher PLQY means brighter fluorescence. These optimized CDs also had a specific carbon-to-oxygen ratio (Rc/o ≈ 2.37) which contributed to their superior performance. Beyond basic characterization, the researchers explored the CDs’ potential as sensors. They found the CDs were sensitive to temperature changes, exhibiting a measurable decrease in fluorescence intensity between 298 and 393 Kelvin. This makes them a potential candidate for powder-state temperature probes. Moreover, the CDs responded to pH levels, with changes in emission intensity observed across a pH range of 3-12. Perhaps most significantly, the CDs demonstrated remarkable selectivity towards iron(III) ions (Fe³⁺). They showed a near-complete quenching of fluorescence – a significant decrease in light emission – in the presence of Fe³⁺, with a detection limit of just 16.15 nanomolar. This is the lowest detection limit reported for hydrothermally synthesized CDs derived from natural precursors. This selectivity is important as it means the CDs can detect Fe³⁺ ions even in complex mixtures without interference from other metal ions. The ability to selectively detect specific ions is a key feature of advanced theranostic nanoagents[3]. Studies have shown that folate-conjugated carbon dots can encapsulate siRNA and target lung cancer cells, releasing them in a reductive environment for gene silencing. While the current study doesn’t focus on therapeutic applications, the high sensitivity and selectivity of these Aloe vera-derived CDs could be integrated into similar systems for real-time monitoring of metal ion concentrations within a biological environment. Similarly, the pH sensitivity demonstrated here aligns with the need for precise pH tracking in targeted drug delivery systems[4], where drug release is often pH-dependent. The research highlights a sustainable and efficient route to produce high-performance carbon dots from a readily available natural source. The optimized synthesis parameters and the resulting CDs’ exceptional sensing capabilities open up possibilities for a wide range of applications in environmental monitoring, biomedical diagnostics, and beyond.

MedicineBiochemPlant Science

References

Main Study

1) Aloe vera derived carbon dots as multifunctional fluorescent probe for temperature, pH, and ferric ion sensing

Published 20th January, 2026

https://doi.org/10.1038/s41598-025-34499-x

Related Studies

2) Nitrogen and sulphur doped carbon dot: An excellent biocompatible candidate for in-vitro cancer cell imaging and beyond.

https://doi.org/10.1016/j.envres.2022.114922

3) Multi-functionalized carbon dots as theranostic nanoagent for gene delivery in lung cancer therapy.

https://doi.org/10.1038/srep21170

4) Fabrication of Folic Acid-Derived Carbon Dot-Conjugated Chitosan Nanospheres as Theragnostic Agents for pH-Responsive Anticancer Drug Delivery.

https://doi.org/10.1021/acsabm.4c01962


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