Color-Coded Single-Particle Pyrophosphate Assay with Dark-Field Optical Microscopy

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Biomolecular Detection

Background:

• Pyrophosphate (PPi) is a crucial biomarker in various biological processes.
• Accurate quantification of PPi is essential for disease diagnosis and monitoring.
• Existing detection methods often lack sensitivity or require complex sample preparation.

Purpose of the Study:

• To develop a sensitive and convenient color-coded single-particle detection method for pyrophosphate (PPi).
• To utilize single gold nanoparticles (GNPs) as probes for PPi quantification.
• To establish a method with a low limit of detection for PPi in biological samples.

Main Methods:

• Employed single gold nanoparticles (GNPs) as probes for PPi detection.
• Utilized GNP-dependent catalytic deposition of copper (Cu) using reduced nicotinamide adenine dinucleotide (NADH).
• Quantified PPi by counting color-coded yellow particles via dark-field optical microscopy, observing localized surface plasmon resonance shifts.

Main Results:

• Achieved a limit of detection as low as 1.49 nM for PPi.
• Established a linear dynamic range of 0-4.29 μM for PPi quantification.
• Demonstrated good recovery efficiency in artificial urine samples, indicating applicability in biological milieu.

Conclusions:

• The developed color-coded single-particle method offers a highly sensitive and convenient approach for PPi quantification.
• This technique surpasses the sensitivity of traditional spectroscopic measurements in bulk solutions.
• The method shows promise for future ultrasensitive detection of various target biomolecules in complex biological environments.