Laser-induced breakdown spectroscopy as a novel readout method for nanoparticle-based immunoassays

Area of Science:

• Analytical Chemistry
• Biotechnology
• Spectroscopy

Background:

• Microtiter plate immunoassays are crucial for biomarker detection.
• Nanoparticle (NP) labels enhance immunoassay sensitivity but require effective readout methods.
• Existing readout techniques may have limitations in terms of label compatibility or complexity.

Purpose of the Study:

• To investigate Laser-induced breakdown spectroscopy (LIBS) as a novel readout method for nanoparticle-based microtiter plate immunoassays.
• To develop and validate the Tag-LIBS technique for quantifying nanoparticle labels.
• To assess the sensitivity, scope, and potential for automation and multiplexing of the LIBS approach.

Main Methods:

• Application of nanosecond ablation sampling for nanoparticle determination from the bottom of 96-well microtiter plates.
• Utilizing collinear plasma emission collection and focusing optics arrangements for LIBS measurements.
• Development of a sandwich immunoassay for human serum albumin using streptavidin-coated silver nanoparticle (AgNP) labels.

Main Results:

• Successful quantification of silver and gold nanoparticles directly from the microtiter plate bottom.
• A sandwich immunoassay for human serum albumin achieved a detection limit of 10 ng·mL⁻¹, comparable to fluorometric methods.
• Demonstrated the ability to detect various NP labels irrespective of fluorescence or catalytic properties.

Conclusions:

• Tag-LIBS is a sensitive and versatile readout technique for nanoparticle-based immunoassays in microtiter plates.
• The method offers advantages such as broad NP label compatibility, potential for automation, and multi-elemental analysis capabilities.
• LIBS presents a promising, fast alternative to conventional readout techniques, particularly for multiplexed biomarker detection.