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Point-of-care impedimetric aptasensor to detect the luteinizing hormone
Pankaj Kumar1,2, Arumugam Anitha1, Ankita Das1,2
1Animal Biotechnology Laboratory, National Institute of Animal Biotechnology, near Gowlidoddi Extended Q City Road, Gachibowli, Hyderabad, 500032, Telangana, India.
Insights
A new aptasensor detects Luteinizing Hormone (LH) using a smartphone, offering a fast, affordable, and field-applicable method for ovulation prediction in cows. This innovation bypasses expensive lab tests for improved artificial insemination success rates.
Area of Science:
- Biosensors
- Veterinary Diagnostics
- Molecular Recognition
Background:
- Luteinizing Hormone (LH) is crucial for predicting ovulation in cattle, enhancing artificial insemination success.
- Current LH detection methods (RIA, ELISA) are costly, time-consuming, and require specialized facilities, limiting field application.
- A need exists for a practical, affordable, and user-friendly LH detection method suitable for on-farm use.
Purpose of the Study:
- To develop a specific, quantitative, and inexpensive aptasensor for field-applicable LH detection.
- To utilize aptamers as stable, cost-effective biorecognition elements instead of antibodies.
- To integrate the aptasensor with a smartphone for easy data acquisition and analysis.
Main Methods:
- Fabrication of a screen-printed gold electrode aptasensor using aptamers for LH recognition.
- Label-free detection of LH via Electrochemical Impedance Spectroscopy (EIS) using a smartphone-enabled device.
- Quantification of LH in biological fluids within 20 minutes using a small sample volume (~20 μL).
Main Results:
- The aptasensor demonstrated a low limit of detection (0.80 ng/mL in buffer, 0.61 ng/mL in serum) and a wide dynamic range (0.01-50 ng/mL).
- High correlation (κ > 0.87) was observed between aptasensor results and standard LH-ELISA in dairy animal serum samples.
- The aptasensor maintained electrochemical sensing ability after 30 days of storage at room temperature.
Conclusions:
- The developed aptasensor provides a rapid, sensitive, and cost-effective alternative for LH detection in veterinary applications.
- Smartphone integration enables field-deployable LH monitoring, facilitating timely ovulation prediction and improving cattle breeding efficiency.
- The aptamer-based approach offers a stable and accessible platform for developing point-of-care diagnostic tools.
Abstract:
Luteinizing hormone (LH) is a useful biomarker for identifying ovulation events in the cows to predict the time of ovulation to achieve a high success rate of conception following artificial insemination. Although antibody-based radioimmunoassay and enzyme-linked immunosorbent assay are being used for LH measurement, these techniques are expensive, time-consuming, and require expertise and sophisticated laboratory facilities. So, there is a need for a field-applicable, affordable, easy-to-use method for LH detection. For developing such a specific, quantitative, and inexpensive system, an aptamer-based smartphone-enabled aptasensor has been investigated. The aptamer was used instead of the antibody as a biorecognition element due to its comparative stability at ambient temperature, ease of synthesis, and cost-effectiveness. Electrochemical impedance spectroscopy has been used to obtain label-free detection of LH within 20 min in ~ 20 μL sample volume. The screen-printed gold electrode is compatible with a smartphone-enabled miniaturized device (Sensit Smart; Palmsens BV, The Netherlands) and was fabricated with the aptamer to detect LH in biological fluids (limit of detection 0.80 and 0.61 ng/mL in buffer and undiluted/unprocessed serum, respectively, with the dynamic range of detection of 0.01 to 50 ng/mL). All the data were obtained in the 10 kHz to 0.10 Hz frequency range at a bias potential of 0.30 V with an alternating potential of 10 mV. The clinical relevance of the sensor was evaluated in 10 serum samples collected from dairy animals which established a high correlation with standard LH-ELISA (κ > 0.87). The aptasensor can be stored at room temperature for 30 days without any significant loss in electrochemical sensing ability.
