Colorimetric Detection of Biothiols Using Nanoparticle Probes

Biothiols such as cysteine, homocysteine and glutathione play pivotal roles in cellular redox balance, metabolic regulation and signalling pathways. Aberrant levels of these low-molecular-weight thiols are implicated in neurodegenerative disorders, cardiovascular disease and cancer. Colourimetric assays employing nanoparticle probes harness the unique optical properties of noble metal nanostructures—principally gold and silver—to translate molecular recognition events into visible colour changes. Surface plasmon resonance and nanoparticle aggregation or etching modulate absorption spectra in response to thiol binding, enabling rapid, low-cost and often naked-eye detection. Such assays marry high sensitivity and selectivity with minimal instrumentation, offering promise for point-of-care diagnostics, environmental monitoring of sulphur compounds and quality control in food and pharmaceutical contexts. Key advances have refined assay kinetics, enhanced discrimination among individual biothiols and extended applications to complex matrices such as serum, urine and industrial effluents.

Research from Nature Portfolio

Recent studies have demonstrated dual-function silver nanoprisms as rapid colourimetric platforms for individual biothiol discrimination. In this approach, biothiols bind covalently to the silver surface, protecting nanoprisms from chloride-induced etching and preserving a characteristic blue–purple hue. Simultaneously, controlled pH adjustments trigger thiol-mediated aggregation of the prisms, yielding distinctive spectral shifts for cysteine, homocysteine and glutathione. The method achieves high sensitivity with detection limits in the sub-micromolar range and completes analysis in under ten minutes, successfully quantifying each thiol in human serum. This work exemplifies how finely tuned nanoparticle surface chemistry and morphology can resolve closely related analytes in biological fluids with minimal sample preparation.

Colorimetric Detection of Biothiols Using Nanoparticle Probes publication trend

The graph below shows the total number of articles in colorimetric detection of biothiols using nanoparticle probes across all publications each year (not limited to Nature Index journals).

Technical terms

Biothiols: Low-molecular-weight thiol-containing compounds (e.g. cysteine, homocysteine, glutathione) involved in redox regulation and signalling.

Nanoparticle probe: A colloidal nanostructure, often metallic, designed to transduce molecular interactions into measurable optical changes.

Surface plasmon resonance (SPR): Collective oscillation of conduction electrons at a metal–dielectric interface that produces strong, tunable absorbance bands.

Aggregation: Process by which nanoparticles cluster, leading to shifts in SPR and visible colour changes.

Etching: Chemical dissolution or morphological transformation of nanoparticles induced by reactive species, affecting their optical signature.

References

1. Spectrophotometric determination of glutathione and cysteine based on aggregation of colloidal gold nanoparticles. Scientia Iranica (2012).
2. Colorimetric detection of individual biothiols by tailor made reactions with silver nanoprisms. Scientific Reports (2021).
3. Gold-Modified Micellar Composites as Colorimetric Probes for the Determination of Low Molecular Weight Thiols in Biological Fluids Using Consumer Electronic Devices. Applied Sciences (2021).
4. A Naked-Eye Colorimetric Ratio Method for the Selective and Sensitive Detection of L-Cys Based on a Silver Nanoflakes–Chromium (III) Ion System. Chemosensors (2024).