Abstract
Sensitive, reliable detection of molecular biomarkers in complex clinical samples through portable biosensors remains a central challenge for early cancer diagnostics. Field-effect transistor (FET) biosensors offer strong potential for miniaturized, low power sensing, yet their clinical translation is often constrained by probe instability, non-specific adsorption and Debye screening-limited signal transduction in serum. Here we present a site-specific anchored FET platform (SNAP-FET) that integrates genetic code expansion and click chemistry to immobilize nanobodies with a controlled, uniform, site-specific orientation in serum, within the Debye length for efficient signal transduction. This strategy yields attomolar-level sensitivity and stable electronic readout of endometrial cancer biomarkers directly in serum, overcoming longstanding limitations of biofluid FET sensing by coupling compact affinity probes with precision interface design. More broadly, the SNAP-FET and its portable implementation, ENDOCARE, provide a generalizable framework for next-generation biochemical sensing in point-of-care settings for early diagnostics in oncology.
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The data that support the findings of this study are available within this article and its Supplementary Information. Source data are provided with this paper.
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Acknowledgements
This work was supported by the National Key R&D Program of China (grant nos. 2020YFA0211200 and 2021YFA1200403), the National Natural Science Foundation of China (grant nos. 22090050, 22474131, U24A20502, 22522402, 22325701 and U22A20332). X.L. was supported by the Natural Science Foundation of Hubei Province (grant no. 2024AFA001) and the Natural Science Foundation of Shenzhen (grant nos. JCYJ20230807113706013). J.D. was supported by the Natural Science Foundation of Hubei Province (grant no. 2025AFA075). We thank the High-Performance Computing Cluster of the AI for Drug Discovery Platform at Peking University for providing computational resources. We also thank the Faculty of Materials Science and Chemistry at China University of Geosciences (CUG) for access to TEM facilities (Talos F200X) and M. Gong for his assistance with data acquisition and analysis. We also thank T. Zhai from the School of Materials Science and Engineering, Huazhong University of Science and Technology, for his technical guidance and support in the fabrication of In2O3 FET.
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Z.Z. and Y.L. contributed equally to this paper. X.L. supervised the project. X.L., Z.Z., J.D., F.X., T.L. and Y.L. conceived and designed the study. Z.Z. fabricated and characterized transistors and devices. Z.Z., Y.L. and Y.J. synthesized probes. Y.L. performed theoretical modelling of orthogonal-1G8-linker complexes. Z.Z., Q.W. and G.L. performed cell and animal experiments. D.Y., J.D. and G.L. provided clinical samples. Z.Z., Y.L. and Q.W. analysed the data and prepared figures. Z.Z., Y.L., T.L. and X.L. drafted the paper. Z.Z., Y.L., Q.W., Y.J., T.L. and X.L. revised the paper. All authors contributed to the writing of the paper.
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Extended data
Extended Data Fig. 1 Schematic diagram of the functionalization process of SNAP-FET.
Schematic diagram of the functionalization process of SNAP-FET.
Extended Data Fig. 2 GCE engineering modification of the 1G8-S85Tet nanobody and its application in HE4 detection.
GCE engineering modification of the 1G8-S85Tet nanobody and its application in HE4 detection. (a) Schematic illustration of the introduction of Tet-v-3.0 at the S85 site via GCE technology. (b) Deconvoluted ESI-MS spectra confirm the precise molecular mass. (c) SDS-PAGE image of the 1G8-S85Tet nanobody. (d-e) Kinetic comparison of orthogonal conjugation efficiency for 1G8-S85AzF and 1G8-S85Tet probes. (d) Time-dependent responses of SNAP-FETs functionalized with 1G8-S85AzF and 1G8-S85Tet probes at different modification durations to 1×10-11 M HE4. Error bars indicate mean ± standard deviation (n = 3). (e) Quantitative kinetics comparison.
Extended Data Fig. 3 Selection of the insertion site for Orthogonal-NT2 and validation of its CA125 detection capability.
Selection of the insertion site for Orthogonal-NT2 and validation of its CA125 detection capability. (a) Schematic illustration of the insertion site for the non-natural amino acid N6-[(2-azidoethoxy)carbonyl]-L-lysine introduced into the nanobody NT2 via GCE technology. (b) Normalized current response (ΔI/I0) of SNAP-FET functionalized with Orthogonal-NT2 compared with four random immobilization strategies (via carboxyl and amino) upon exposure to 100 U/mL CA125. Dots represent individual independent samples, and bars indicate mean ± standard deviation (n = 3). (c) Normalized current response ΔI/I0 of NT2-Q13AzK-modified SNAP-FET and bare In2O3 at different CA125 concentrations. Error bars indicate mean ± standard deviation (n = 3).
Extended Data Fig. 4 Preparation and performance verification of SNAP-FET with Ag/AgCl side gates.
Preparation and performance verification of SNAP-FET with Ag/AgCl side gates. (a) Fabrication of In2O3 FET with integrated Ag/AgCl side-gate electrodes. Starting from conventional In2O3 FET devices, electron-beam lithography (EBL) was used to define a patterned area between the source and drain electrodes. A Cr/Au layer (3 nm / 40 nm) was deposited by thermal evaporation to form a gold pad for Ag/AgCl deposition. Subsequently, 0.1 μL of Ag/AgCl paste was drop-cast onto the distal end of the gold pad to create a prototype Ag/AgCl gate electrode, yielding In2O3 FET devices with integrated side-gate configuration. (b) Schematic diagram of the working principle of SNAP-FET with Ag/AgCl side gate. (c) Normalized signal response (ΔI/I0) measured at VGS = 215 mV (Ag/AgCl side gate) and VGS = 200 mV (Ag/AgCl external gate) of In2O3 FET biosensors. The biosensors were tested in PBS upon exposure to HE4 (1× 10-14 M) and CA125 (3.75 × 10-2 U/mL). Dots represent individual independent samples, and bars indicate mean ± standard deviation (n = 8). Statistical significance was assessed using a two-sided unpaired t-test. No significant difference was observed between the two gating configurations for either biomarker (HE4, P = 0.7718; CA125, P = 0.0808); ns indicates not significant.
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EC biomarker detection by ENDOCARE POCT device.
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Zhang, Z., Li, Y., Jing, Y. et al. Oriented nanobody–field-effect transistor interfaces enable ultrasensitive cancer biomarker detection. Nat. Sens. (2026). https://doi.org/10.1038/s44460-026-00040-4
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DOI: https://doi.org/10.1038/s44460-026-00040-4


