An electrochemical immunosensor designed for the simultaneous detection and quantification of acid α-glucosidase (GAA), β-glucocerebrosidase (GBA), and galactocerebrosidase (GALC) has been developed for early testing of lysosomal storage diseases (LSDs) including Pompe, Gaucher, and Krabbe diseases, respectively, as published in Scientific Reports.
The device was able to detect the molecules down to the femtomolar level with GAA detected as low as 0.12 pg/mL (1.5 fM), GBA at 0.31 pg/mL (5.19 fM), and GALC at 0.18 pg/mL (2.25 fM).
The sensors also displayed high selectivity when tested with 0.5 ng/mL solutions of each individual molecule with very low levels of response observed for the other 2 molecules which were not contained in the samples. When tested with a mixture of both 0.5 ng/mL GAA and GBA, the sensor was able to detect significant signals for each specific molecule.
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The electrodes also exhibited good recovery when exposed to spiked human serum with recovery values ranging from 90.5% for GBA to 105.2% for GAA. The good recovery in human serum suggests high precision of the sensors and their applicability in different biological specimens, the authors said.
“The immunosensor showed good selectivity, sensitivity and good recovery when spiked in human serum, which confirms its possible applicability in point-of-care testing for the early diagnosis of LSDs,” they said.
The immunosensor was developed using carbon microarray disposable chips that have been electroplated with gold nanoparticles. The gold nanoparticles allow for high conductivity and high surface area for the immobilization of antibodies to GAA, GBA, and GALC. The antibodies adhered via functionalization with cysteamine and glutaraldehyde.
Nonspecific binding of the electrodes was blocked using ethanolamine to prevent false signals. Stability testing of the sensors revealed that storage in a humid container at 4 °C for a month resulted in only a 2.3%-3% decrease in signal amplitudes.
Abdulkarim H, Siaj M. Label-free multiplex electrochemical immunosensor for early diagnosis of lysosomal storage disorders. Sci Rep. 2022;12(1):1-8. doi:10.1038/s41598-022-13259-1