Fluorescent Sensing Techniques for Analytes in Biological Samples

Fluorescent sensing has emerged as a versatile and powerful approach for the detection of small molecules, ions and biomacromolecules in complex biological matrices. By harnessing the unique optical properties of fluorophores—ranging from organic dyes and fluorescent proteins to semiconductor quantum dots and carbon-based nanodots—researchers can achieve high sensitivity, rapid response times and the potential for real-time monitoring. Key strategies include turn-on or turn-off probes, ratiometric sensors with built-in referencing, and multiplexed platforms capable of simultaneous detection of multiple targets. Advances in nanomaterial synthesis and surface engineering have endowed such sensors with improved water solubility, biocompatibility and selectivity, enabling applications in point-of-care diagnostics, metabolic profiling, drug monitoring and environmental biomonitoring. Typical analytes include vitamins, neurotransmitters, pharmaceuticals, metal ions and enzymatic substrates. Critical challenges remain in overcoming background autofluorescence, ensuring quantitative readouts in heterogeneous samples and translating laboratory prototypes into practical devices for clinical and field use.

Research from Nature Portfolio

Recent studies have demonstrated the efficacy of dual-emission ratiometric fluorescence systems for precise drug quantification in biological fluids. One example employs amine-functionalised carbon quantum dots coupled with rhodamine B to create a two-channel sensor that internally corrects for environmental fluctuations. Binding of the target drug selectively quenches the quantum-dot emission at one wavelength while leaving the reference dye unchanged, yielding a concentration-dependent fluorescence ratio. Optimisation of pH, probe composition and interaction time afforded a low nanomolar detection limit and excellent repeatability, and successful measurements were reported in spiked serum and urine samples.

Fluorescent Sensing Techniques for Analytes in Biological Samples publication trend

The graph below shows the total number of articles in fluorescent sensing techniques for analytes in biological samples across all publications each year (not limited to Nature Index journals).

Technical terms

Quantum dots: Nanometre-scale semiconductor particles that exhibit size-tunable fluorescence emission and high photostability.

Ratiometric fluorescence probe: A sensor design featuring dual emission wavelengths to provide built-in self-referencing and mitigate environmental interferences.

Inner filter effect: A phenomenon in which absorption of excitation or emission light by an analyte or matrix reduces observed fluorescence intensity, often exploited for sensing metal ions.

Host–guest chemistry: A supramolecular approach in which a macrocyclic host molecule selectively binds an analyte guest, leading to measurable optical changes.

Nanozyme: A nanomaterial with enzyme-like catalytic activity, used to generate or enhance fluorescence signals for analyte detection.

References

1. Sensitive detection of tamsulosin hydrochloride based on dual-emission ratiometric fluorescence probe consisting of amine-carbon quantum dots and rhodamine B. Scientific Reports (2021).
2. Cucurbit[6]uril-based carbon dots for recognizing l -tryptophan and capecitabine. Materials Chemistry Frontiers (2022).
3. Fluorometric Detection of Thiamine Based on Hemoglobin–Cu3(PO4)2 Nanoflowers (NFs) with Peroxidase Mimetic Activity. Sensors (2020).