A recent study published in Small explores how nano-phase separation influences analyte binding in aptasensors, using advanced nano-infrared (nano-IR) spectroscopy.
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Aptasensors, which use aptamers as recognition elements, are gaining traction in medical diagnostics, environmental monitoring, and food safety. Understanding how these sensors function at the nanoscale can help improve their performance.
This research examines the physical and chemical changes that occur when aptasensors interact with target molecules, offering valuable insights for refining biosensing technologies.
Why Nano-Phase Separation Matters
The effectiveness of an aptasensor comes down to how well its surface materials interact with target molecules. At the nanoscale, phase separation—where different materials naturally separate into distinct regions—can impact how well a sensor detects and binds to an analyte. The study highlights how understanding these small-scale structural changes can help improve sensor design and function.
Gold substrates, particularly those with well-ordered Au(111) facets, are commonly used in aptasensors because of their excellent electronic properties and ease of modification. Incorporating polymers like polyethylene glycol (PEG) into these systems introduces phase separation effects that can influence binding behavior. By studying these material interactions, researchers aim to fine-tune sensor surfaces to improve detection accuracy and reliability.
How the Study Was Conducted
The researchers used a combination of nano-infrared spectroscopy and atomic force microscopy (AFM-IR) to examine nano-phase separation and analyte binding in detail. These techniques provided high-resolution images and spectral data, helping the team analyze material composition at the nanoscale.
To ensure accuracy, they normalized spectral data, accounting for variations in tip-surface interactions and laser power fluctuations. By focusing on specific vibrational modes, such as the symmetric phosphate stretch (νs(PO2)-), they could track how surface modifications—like PEG attachment—affected molecular binding.
Additional techniques, including Infrared Reflection Absorption Spectroscopy (IRRAS) and Attenuated Total Reflection Infrared Spectroscopy (ATR-IR), provided further insights into the surface chemistry and molecular behavior of the sensors. The team also carefully controlled measurement conditions to reduce interference and ensure consistent results.
Key Findings
Nano-IR spectroscopy revealed noticeable shifts in spectral patterns when analytes bound to the aptasensor surface, indicating structural changes in the aptamers. These shifts provided clues about how aptamers adapt their shape when interacting with target proteins.
One of the most important takeaways was that phase separation improved the sensors' sensitivity. The findings suggest that optimizing polymeric interfaces can enhance selectivity and binding efficiency. The researchers also used tapping-mode atomic force microscopy (TM AFM) to study the surface topography, confirming that structural variations directly affected sensor performance.
The study emphasizes that understanding nanoscale material behavior can lead to better sensor designs with greater specificity and less interference from non-target molecules. By analyzing the physical changes that occur during binding, researchers can refine sensor surfaces to improve detection reliability.
Beyond these findings, the work opens opportunities for further research into how nano-phase separation can be used to refine sensor technologies for different applications, from disease detection to environmental analysis.
Journal Reference
Samiseresht N., et al. (2025). Nano-Phase Separation and Analyte Binding in Aptasensors Investigated by Nano-IR Spectroscopy. Small. DOI: 10.1002/smll.202409369, https://onlinelibrary.wiley.com/doi/10.1002/smll.202409369