Recent advances in single-molecule biosensing are reshaping how scientists approach the detection and analysis of biomolecules. In a newly released Nature Communications article, Vu, Janssen, de Jong and Prins present a powerful method to monitor low concentration biomarkers in real-time, using reversible nanoswitches combined with single-molecule detection. Their work represents an important step forward in the field of continuous biosensing, where both sensitivity and speed are critical.
Detecting biomolecules at extremely low concentrations, often in the picomolar range, remains a major challenge in biological science, biomedical research, and industrial monitoring. Traditional biosensors typically rely on ensemble measurements, where the signal comes from the average behavior of millions of molecules. While effective in many cases, these approaches can limit sensitivity, mask sample heterogeneity, and slow down the detection process.
This shift changes the paradigm. Instead of measuring an averaged signal, it enables the detection of individual molecular interactions, one event at a time. It opens the door to highly sensitive detection, improved data analysis, and deeper insights into biological systems at the molecular level. Techniques such as optical detection, fluorescence microscopy, plasmonic sensing, and label-free approaches are driving this evolution, offering new ways to capture weak signals with high precision.
In this context, the ability to combine single-molecule sensitivity with continuous, integrated monitoring platforms is particularly valuable. Applications range from biomarker detection in clinical environments to process monitoring in biopharma, where fast and reliable data can directly impact decision-making. However, achieving both high sensitivity and rapid response remains a complex engineering and scientific challenge.
The publication highlighted here addresses this exact problem. By leveraging single-molecule detection and innovative sensing principles, it demonstrates how continuous monitoring of low concentration biomarkers can become both feasible and practical. Beyond the scientific breakthrough, it also shows how advances in biosensing, fluidic control, and system integration are converging to unlock new possibilities.
At its core, this technique is about pushing detection to the ultimate limit, the individual molecule level. Instead of relying on averaged signals from large populations, these approaches detect and analyze events such as the binding of a protein, a DNA sequence interaction, or a chemical reaction occurring at a surface. This shift in perspective has a major impact on how biological systems are understood and measured.
Comparison between ensemble-based biosensing and single-molecule detection. While traditional methods rely on averaged signals from large populations, single-molecule approaches capture discrete binding events, enabling higher sensitivity and access to molecular heterogeneity. From Single Molecule Spectroscopy (SMS). 2010/6/9 Miyasaka Lab. Iida Atsushi. Contents. Introduction -History of Single Molecule Spectroscopy (SMS) -Difference between ensemble and single-molecule measurement
Traditional biosensing methods, including many optical or electrochemical assays, generate a signal that reflects the collective behavior of millions of molecules. While robust, this approach can hide important details. Variations between molecules, transient interactions, or rare events are often lost in the averaged signal. In contrast, single-molecule detection captures these individual interactions directly, providing access to sample heterogeneity, binding dynamics, and stochastic processes that are otherwise invisible.
A key advantage is single-molecule sensitivity. Because each event is counted or tracked independently, even extremely low concentrations of biomolecules can be detected with high precision. This is particularly relevant for biomarker detection, where early-stage signals may be present at very low levels. By improving both sensitivity and specificity, single-molecule biosensors enable more accurate analysis in complex biological environments.
Several technologies support this capability. Optical detection methods, such as fluorescence microscopy or interferometric scattering, can monitor changes in light at the nanoscale. Plasmonic biosensors, often based on gold nanostructures, enhance local electromagnetic fields to amplify weak signals. Other methods, such as nanopore sensing or particle-based systems, rely on changes in electrical or mechanical properties. Whether label-based or label-free, these techniques are designed to detect and quantify interactions with minimal signal loss.
Another important benefit is the ability to study molecular interactions in real-time. Instead of waiting for equilibrium or endpoint measurements, researchers can follow binding kinetics, observe association and dissociation events, and extract dynamic information from the signal. This is essential for understanding biological processes, screening drug candidates, or optimizing biochemical reactions.
In short, single-molecule biosensing is not just about detecting smaller quantities. It fundamentally improves how data is generated and interpreted. By enabling high-resolution, real-time analysis of individual molecular events, it provides deeper insights into biological systems and opens new possibilities for continuous monitoring, advanced diagnostics, and precision-driven applications.
Achieving continuous biosensing at such levels is not just a detection problem, it is a balance between competing constraints. On one side, detecting biomolecules at the picomolar level requires high sensitivity, meaning the system must be able to capture and measure extremely weak signals. On the other side, continuous monitoring demands fast response times, so that changes in concentration can be tracked in real-time.
In many conventional biosensors, improving sensitivity often comes at the cost of speed. High-affinity binding is typically used to capture rare biomolecules, but this also slows down the system. Once a molecule binds, it tends to stay attached for longer, which delays signal refresh and limits the ability to follow dynamic changes. This creates a fundamental limitation for continuous monitoring.
Under these conditions, molecular interactions become rare and stochastic. The signal generated by binding events is weak and often buried in noise. In ensemble-based systems, this results in slow signal accumulation and reduced accuracy. Even in advanced optical or plasmonic biosensors, detecting such low levels requires either long acquisition times or signal amplification strategies.
Another challenge comes from binding kinetics. When the concentration of analytes are very low, the rate at which molecules interact with the sensor surface is also low. This leads to delayed responses and makes it difficult to obtain reliable measurement data within a short time window.
Continuous biosensing introduces additional constraints beyond simple detection. The system must operate over time without interruption, which means:
This is especially challenging when working with biological samples, as conditions can change over time and non-specific interactions may affect the signal.
Most traditional biosensing platforms were not designed for continuous, real-time detection at low concentrations. They often rely on endpoint measurements, washing steps, or signal accumulation over time. While effective for many assays, these approaches are not well suited for applications that require:
As a result, there is a growing need for new biosensing technologies that can combine single-molecule sensitivity, fast response, and stable operation over time.
Addressing these challenges requires rethinking how signals are generated and measured. Instead of relying solely on signal intensity or equilibrium states, newer approaches focus on event-based detection, where individual binding and unbinding events are tracked over time. This opens the door to continuous single-molecule monitoring, where information is extracted from the dynamics of the system rather than from a static signal.
Illustration of the trade-off in biosensing systems. At low analyte concentrations, achieving high sensitivity often requires strong binding interactions, which can slow down response time and limit real-time monitoring capabilities. From : https://doi.org/10.3390/bios13040428
This is precisely the direction explored in the publication, where a novel strategy enables both high sensitivity and real-time detection, even at very low biomarker concentrations.
This publication introduces a new strategy in single-molecule biosensing that directly addresses the limitations of traditional approaches. Instead of relying on stronger binding or signal amplification, it rethinks how detection is performed at the molecular level.
Different types of nanoswtiches from the study
The approach is based on a combination of:
Small engineered systems that can switch between states when a molecule binds and unbinds
Each binding event is detected individually, instead of measuring an averaged signal
The signal is not the intensity, but the frequency of molecular interactions over time
This means the system counts how often molecules bind and unbind, rather than how many are bound at equilibrium.
This design brings several key advantages:
The signal reacts immediately to concentration changes because it depends on event frequency, not equilibrium
Even rare molecular events can be detected and quantified
Unlike traditional biosensors, strong binding is not required to achieve sensitivity
The system can track dynamic changes without stopping or resetting
This challenges the conventional assumption that detecting low concentrations requires strong, slow-binding interactions.
Using this approach, the authors show that:
In simple terms, the more molecular events are detected, the more accurate the measurement becomes.
This work highlights an important evolution in the field:
This shift opens new possibilities for continuous biosensing, where both speed and sensitivity are required, and where understanding molecular interactions in real-time becomes essential.
To demonstrate this new approach in single-molecule biosensing, the authors combine experimental setup, optical detection, and modeling. The goal is not only to show that the concept works, but also to understand how the signal is generated and controlled at the molecular level.
The sensing principle relies on sandwich-type nanoswitches. Two binding elements interact with the target molecule, creating a reversible connection between a probe and a surface. When this interaction occurs, the system switches between two states, which can be detected and analyzed over time.
To capture these events, the study uses a particle-based optical detection method. Microscopic particles are tracked in real-time using video microscopy. Their motion changes depending on whether a molecular bond is formed or not. This allows the system to detect individual binding and unbinding events, providing a direct readout of molecular interactions.
The experiments are performed in a controlled fluidic environment, where samples are introduced and transported using an automated setup. Measurements are recorded continuously, enabling the extraction of binding kinetics, switching activity, and event frequency. This real-time data is essential to quantify low concentration biomarkers.
In parallel, the authors develop a rate-based model and Monte Carlo simulations to describe the system. These models help explain how parameters such as binding rates, number of binding sites, and measurement time influence the performance of the biosensor. They also show how signal variability and measurement precision are linked to the stochastic nature of single-molecule events.
Overall, the methodology combines optical sensing, controlled fluidics, and data-driven modeling to provide a complete understanding of how continuous single-molecule detection can be achieved in practice.
A critical aspect of this work lies in the fluidic architecture, which enables stable and reproducible single-molecule biosensing under continuous operation. While the sensing principle is based on nanoswitches and optical detection, the quality of the measurement signal strongly depends on how samples are handled, transported, and refreshed in the system.
The experiments are performed in a flow-based configuration, where analyte solutions are introduced into a microfluidic chamber and maintained under controlled conditions. This requires:
In this study, fluid handling is achieved using an automated setup combining a programmable syringe pump and a multi-port rotary valve. This configuration allows sequential injection of samples, buffer solutions, and air segments, while maintaining a controlled environment for continuous measurements.
At picomolar concentrations, even small volumes of residual liquid can significantly impact measurement accuracy. The system must therefore minimize:
The use of air gaps between samples, combined with controlled routing through the valve, helps isolate fluids and reduce cross-contamination. This is essential for maintaining the integrity of single-molecule detection, where signal variations are directly linked to molecular events.
Continuous biosensing requires the system to operate over extended periods without drift. This imposes constraints on:
In this setup, measurements are performed in no-flow conditions after sample injection, allowing the system to observe binding and unbinding events without perturbation. This hybrid approach, combining controlled flow and static measurement phases, is key to achieving reliable real-time monitoring.
Fluidic automation is tightly coupled with the sensing and acquisition system. The timing of injections, incubation phases, and measurements must be synchronized with:
This level of integration ensures that the recorded signal accurately reflects molecular interactions at the surface, without artifacts introduced by fluidic disturbances.
Overall, fluidic automation plays a central role in transforming a sensitive detection principle into a reliable experimental platform. By ensuring:
It enables reliable extraction of data from inherently stochastic single-molecule events, and supports the transition toward continuous, real-time biosensing systems.
Experiments like the one presented in this publication rely heavily on precision fluid handling and system integration. While the sensing principle is based on single-molecule biosensing, its performance depends on how well the fluidic environment is controlled.
Solutions such as AMF’s laboratory programmable syringe pumps, LSPone (used in the study) and microfluidic rotary valves are designed for this type of application. They enable:
In setups where single-molecule detection is combined with continuous monitoring, this level of control is essential. It ensures that the measured signal reflects true molecular interactions, not artifacts from fluid instability or sample handling.
The ability to detect and analyze single molecular events in real-time opens up a wide range of applications, especially when combined with dynamic monitoring and high sensitivity.
In biomedical and clinical settings, single-molecule biosensing enables early biomarker detection at very low concentrations. This is particularly important for diseases where signals appear at the early stage, such as cancer or inflammatory conditions. By providing real-time data on protein levels or molecular interactions, these technologies support more responsive and precise approaches in personalized medicine.
In life science research, single-molecule detection offers a powerful way to study DNA, nucleic acids, and protein interactions. Researchers can observe binding kinetics, transient states, and molecular behavior that are not accessible with ensemble measurements. This leads to deeper insights into biological processes, from gene expression to molecular signaling pathways. In drug development, these techniques are used to analyze how compounds interact with their targets at the molecular level. Monitoring binding and dissociation events in real-time helps evaluate drug candidates more accurately, improving both screening and optimization phases.
Beyond healthcare, industrial and environmental applications are also emerging. In bioprocess monitoring, continuous biosensing can provide real-time information on key molecules, enabling better process control and optimization. In areas such as food safety or environmental monitoring, detecting trace levels of contaminants or biomolecules can improve reliability and response time.
Overall, single-molecule biosensing is evolving from a research tool into a versatile platform for detection, monitoring, and analysis across multiple domains. Its ability to combine high sensitivity, real-time measurement, and detailed molecular insight makes it a key technology for next-generation sensing applications.
What’s next for single-molecule biosensing
The future of single-molecule biosensing lies in turning highly sensitive laboratory methods into robust, integrated real-time monitoring platforms. While recent advances show strong potential, several challenges remain, including signal stability, noise control, and system integration.
At the same time, new opportunities are emerging. The combination of advanced optical detection, improved materials, and smarter data processing, including machine learning, will enhance both sensitivity and accuracy. Integration with microfluidic automation will also play a key role in enabling scalable and reliable systems.
As the field evolves, single-molecule biosensing is expected to move beyond research applications toward clinical diagnostics, industrial monitoring, and continuous biological analysis, unlocking new possibilities for understanding and controlling complex systems.
This publication provides a detailed view of how single-molecule biosensing can enable continuous, real-time detection of low concentration biomarkers, combining experimental validation with modeling and system design.
To explore the full study, including the sensing principles, simulation models, and experimental setup, you can access the original article here :
Single-molecule readout of reversible nanoswitches enables continuous monitoring of low biomarker concentrations – Chris Vu, Selina A. J. Janssen, Arthur M. de Jong & Menno W. J. Prins – Nature Communications – March 2026 – https://doi.org/10.1038/s41467-026-71690-8
It’s a valuable resource for anyone working on biosensing technologies, microfluidic systems, or real-time molecular analysis, and looking to understand the next generation of high-sensitivity detection platforms.
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