Exploring
new functions of nanomaterials can help facilitate the
development of biosensors for the detection of antibiotics. Herein,
a new detection modality based on monovalent antigen-induced aggregation
(MAA) of immunomagnetic beads (IMBs) was proposed for rapid and label-free
detection of enrofloxacin (ENR), which endowed IMBs with the abilities
of both sample separation and signal generation. In the presence of
ENR, the initially well-dispersed IMBs were aggregated and the degree
of aggregation was in a concentration-dependent manner. After exploring
the mechanism underlying IMB aggregation and investigating the key
parameters affecting it, a label-free biosensing platform was developed
for rapid and sensitive detection of ENR. Based on the significant
differences in the magnetic separation speed and size between the
aggregated and well-dispersed IMBs, two methods were proposed for
quantitatively determining ENR, i.e., measuring the turbidity of the
IMB supernatant after magnetic separation for a given time and visualizing
and calculating the grayscale value of the aggregated IMBs trapped
on the surface of a nitrocellulose membrane. A three-dimensional (3D)-printed
syringe was designed and fabricated for automatic filtration of IMBs.
This immunosensor allowed for sensitive detection of ENR in less than
15 min without any labels. It exhibited a satisfactory limit of detection
of 0.79 ng mL–1 and showed the feasibility for ENR
detection of spiked chicken meat with recovery rates ranging from
74.8 to 98.3%. The MAA immunosensor can act as a promising tool to
detect trace levels of ENR and has the potential to be applied to
complex food samples.
HighlightsA practical magnetic separation device was designed, fabricated, and evaluated for enrofloxacin detection.Coupled with a fluorescent biosensor, the device could automatically process a sample in 50 min.The device performed incubation and magnetic separation using a pipette method.The device has the advantages of low-cost and feasibility for on-site detection.Abstract. Antibiotic residues have been a continuing concern in food safety, raising a great issue in human health. For rapid detection of antibiotics, an automated device was developed that can capture and separate a target analyte based on immunomagnetic beads. This automated separation device is suitable for separating the magnetic beads in a preprocessing step, with liquid transfer and magnetic enrichment functions. The device was combined with a fluorescent biosensor to simplify the cumbersome pretreatment of enrofloxacin. In our experiments, enrofloxacin in water samples was used as the detection object, and the entire process could be completed in less than 50 min with automated operation. The lower limit of detection reached 54 ng mL-1 (S/N = 3). The fluorescent biosensor has been enhanced with this automated separation device for more sensitive rapid detection of antibiotic residues in the food supply chain and environment. Keywords: Antibiotic detection, Automation, Fluorescent biosensor, Immunomagnetic separation, Sample pretreatment.
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