The core argument of the perspective is a reframing of what modern pathogen monitoring needs to achieve. For decades, the dominant measure of progress in detection technology has been analytical sensitivity, the ability to find ever smaller quantities of a target organism in a sample. The authors contend that sensitivity, while still important, is no longer the decisive bottleneck. In their view, the key challenge is no longer simply detecting pathogens with greater sensitivity, but increasing monitoring frequency and expanding surveillance from individual targets to multiple priority pathogens in near real time. In other words, a system that detects one pathogen exquisitely well, once a week, after samples have been shipped to a central laboratory, offers far less protective value than a system that watches many pathogens continuously at the point of concern.

The limitations the authors describe are rooted in the architecture of established microbiological methods rather than in any single technical weakness. Traditional culture-based methods, in which microorganisms are grown on or in nutrient media and identified by their growth characteristics, remain valuable in one crucial respect: they determine whether the microorganisms found in a sample are viable, or alive and capable of reproduction. That information matters enormously for risk assessment, because genetic material from dead organisms does not necessarily indicate an active threat. However, culture methods are slow, often requiring days of incubation, and they are poorly suited to organisms that are difficult to cultivate. They also demand trained personnel, laboratory infrastructure and physical sample transport.

Molecular approaches have transformed pathogen detection over the past several decades. Polymerase chain reaction, or PCR, amplifies specific genetic sequences so that tiny amounts of pathogen DNA or RNA can be detected with high sensitivity. Sequencing technologies go further, allowing detailed characterization of the organisms present in a sample, including the identification of strains, virulence factors and antimicrobial resistance genes. Yet the authors point out that even these powerful molecular tools commonly depend on sample collection, laboratory processing, specialized instruments and subsequent analysis. Each of those steps introduces delay, cost and logistical complexity, which together limit their usefulness for continuous, in situ monitoring, meaning monitoring performed directly at the site of the water body or water system being watched.

To bridge the gap between laboratory-grade analysis and real-time field surveillance, the perspective highlights several emerging technologies that the authors believe could serve as complementary layers in a redesigned monitoring architecture. The first is nanobody-based recognition coupled with fiberoptic sensors. Nanobodies are small, single-domain antibody fragments derived from camelid antibodies that retain antigen-binding capacity while being far smaller, more stable and easier to produce than conventional antibodies. When deployed on the surface of fiberoptic sensors, which convert biological binding events into measurable optical signals, they could enable rapid first-line screening of several predefined pathogens at once, acting as a broad biological tripwire that flags when any of a panel of priority organisms appears in the water.

A second technological layer involves functional nucleic acids, a class of synthetic molecules that includes aptamers and deoxyribozymes. Aptamers are short, single-stranded DNA or RNA sequences that fold into specific three-dimensional shapes capable of binding target molecules with antibody-like affinity and specificity. Deoxyribozymes, or DNA enzymes, are catalytic DNA sequences that can perform chemical reactions, including the sequence-specific cleavage of nucleic acid targets. In the surveillance framework proposed by the authors, these probes could provide a more specific secondary analysis, refining or confirming the preliminary signal generated by the first-line screening step. Because functional nucleic acids are chemically synthesized, they can be selected in the laboratory for virtually any target, are relatively stable, and can be regenerated or integrated into amplification schemes, characteristics that make them attractive for repeated-use sensing surfaces.

The third enabling technology is microfluidics, the engineering discipline concerned with manipulating small volumes of fluids through channels measured in tens or hundreds of micrometers. Microfluidic platforms could automate the sample handling steps that currently consume much of the time and labor in pathogen testing, and they could run many detection reactions in parallel on a single chip. By miniaturizing and integrating filtration, reagent mixing, splitting into multiple channels and signal readout, microfluidics offers a path toward devices that continuously process water samples and test them against an entire panel of pathogen targets without human intervention between sampling and result.

Bringing these components together, the authors sketch an end-to-end framework illustrated in the paper. Automated sampling draws water at regular intervals without an operator on site. Pathogen concentration steps overcome the fundamental dilution problem of environmental monitoring, in which even contaminated water may contain vanishingly few target organisms per liter. Multiplex recognition, the simultaneous interrogation of many targets, is then performed by the nanobody-fiberoptic and functional nucleic acid layers, followed by rapid signal detection, computational data analysis and, crucially, early warning: the automated flagging of results that meet predefined risk thresholds. Importantly, the framework does not discard the classical toolkit. Culture, PCR and sequencing remain available within the system for confirmation and deeper characterization whenever the rapid screening layer raises a flag, preserving the viability information and strain-level detail that only those methods can provide.

The authors are careful to emphasize that practical deployment will require far more than highly sensitive sensors, and this candor is one of the most valuable aspects of the perspective. Environmental water is a hostile medium for analytical instruments. Pathogen concentrations in real water bodies are typically very low, demanding extreme analytical performance. Water matrices are chemically and biologically complex, containing sediments, organic matter, salts and competing microorganisms that can interfere with recognition and signal transduction. Biofouling, the accumulation of microbial films on sensor surfaces, can degrade performance within days. Sensor drift, the gradual change in a device’s response over time, undermines the long-term comparability of measurements. Cross-reactivity, in which a probe binds unintended targets, threatens the specificity that multiplex panels depend on. Calibration across seasons and sites, and simply keeping instruments operating stably over months or years in the field, remain unsolved engineering problems that no amount of laboratory sensitivity can compensate for.

The vision that emerges is therefore not one of replacement but of complementarity. Rather than displacing established laboratory methods, the authors envision biosensors as tools that could shorten response times and strengthen early warning systems, forming a rapid outer ring around the slower but more definitive core of conventional analysis. If the engineering challenges they identify can be met, integrating these technologies into reliable multipathogen surveillance networks may materially improve aquatic biosafety, supporting faster management of waterborne biological risks and, ultimately, safer water for the communities that depend on it. The perspective, published as Li and colleagues’ article in Biocontaminant, offers researchers and water managers a candid map of both the promise and the unfinished work on the road to continuous, multipathogen monitoring.

Subject of Research: Real-time multipathogen biosensing for waterborne pathogen surveillance and aquatic biosafety

Article Title: From single-target tests to real-time multipathogen surveillance for safer water

Article References: From single-target tests to real-time multipathogen surveillance for safer water. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: waterborne pathogens, biosensors, nanobodies, fiberoptic sensors, aptamers, deoxyribozymes, microfluidics, PCR, sequencing, early warning systems, aquatic biosafety, water quality monitoring