Data Repository: A gFET-based Aptasensor for Specific Quantification of the Hormone-like Anti-Aging Protein Klotho in Human Serum

The Klotho (KL) gene encodes a single-pass transmembrane protein that functions as a potent suppressor of aging. In humans, reduced Klotho expression is associated with aging, diabetes, Alzheimer’s disease and other age-related disorders, correlating with increased all-cause mortality. The full-length α-Klotho protein consists of two extracellular domains, KL1 and KL2, which are proteolytically cleaved to generate the soluble form – the predominant species in circulation, which is difficult to detect in plasma. Among these, KL1 is the key functional domain, mediating most of Klotho’s enzymatic and signaling activities, including the modulation of fibroblast growth factor (FGF) pathways and glycan processing, making it a critical target for biomarker development. In this study, using FluMag-SELEX we selected an aptamer library specifically recognizing α-Klotho and its KL1 domain in human serum. After nine rounds of enrichment, followed by qPCR, fluorescence microscopy and fluorometric microtiter plate assays, the aptamer pool exhibited high affinity and specificity towards α-Klotho. We then developed an Aptamer-Linked Fluorescence Assay (ALFA) that enabled selective detection of α-Klotho in human serum, effectively distinguishing it from β-Klotho and homologous proteins. Finally, integration of the aptamers into a graphene field-effect transistor (gFET) achieved label-free, specific and fast quantification with high sensitivity in complex biological matrices. Together, these complementary aptamer-based technologies establish a stable, antibody-free strategy for quantifying Klotho isoforms and particularly KL1, providing a promising platform for longevity and age-related biomarker detection.