# Aptamer modified magnetic nanoparticles for the determination of the allergenic protein α-lactalbumin in food samples

## TL;DR

Scientists developed a new method using magnetic nanoparticles modified with aptamers to detect a milk allergen in food samples.

## Contribution

Aptamer-modified magnetic nanoparticles were developed for efficient and affordable allergen detection in food.

## Key findings

- The method achieved high recovery rates (80.0–96.9%) and good precision (RSD < 5.5%) for α-lactalbumin detection.
- The detection limit was as low as 0.04 μg·mL⁻¹, making it suitable for trace allergen analysis.
- The sorbent cost less than 4.2 € per unit, making it affordable for routine use.

## Abstract

Aptamer-modified magnetic nanoparticles (Apt-MNPs) were synthetized and used as a magnetic solid-phase extraction (MSPE) sorbent for the selective isolation of α-lactalbumin (α-LA), an allergenic protein from cow’s milk. For this purpose, a thiol-terminated Apt was immobilized onto the surface of vinyl-functionalized MNPs via "thiol-ene" click chemistry reaction. The resulting Apt-modified MNPs were characterized and several parameters that affect the Apt-based MSPE efficiency were investigated. Under the optimal conditions, the developed Apt-based MSPE protocol was applied to the determination of α-LA in different foodstuffs (dairy-free products and those with declared milk content), yielding satisfactory recoveries (80.0–96.9%), good precision (RSD < 5.5%), and a low limit of detection (0.04 μg·mL⁻1). Moreover, the Apt-based sorbent proved to be highly affordable, with a cost of less than 4.2 € per sorbent, further supporting its suitability for routine analysis.

The online version contains supplementary material available at 10.1007/s00604-026-07936-5.