Electrostatic attraction-based “signal-on” mode immunosensor with a label-free format for sensitive electrochemical detection of thyroid-stimulating hormone in serum
Journal of Electroanalytical Chemistry, cilt.1020, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 1020
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jelechem.2026.120508
- Dergi Adı: Journal of Electroanalytical Chemistry
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC
- Anahtar Kelimeler: Electrochemical thyroid-stimulating hormone sensor, Electrostatic interaction, Hyperthyroidism, Hypothyroidism, Thyroid-stimulating hormone
- Yıldız Teknik Üniversitesi Adresli: Evet
Özet
Thyroid-stimulating hormone (TSH) is a critical biomarker for the early diagnosis of congenital hypothyroidism (CHT), particularly in neonatal screening programs. This study presents a label-free electrochemical immunosensor that employs a “signal-on” detection mechanism for highly sensitive quantification of TSH in artificial serum. The sensing platform is based on a screen-printed graphene electrode (SPGE) modified with a chitosan/glutaraldehyde mixture to enable stable covalent immobilization of anti-TSH antibodies (AbTSH) due to the formation of a Schiff base. Unlike conventional sandwich immunoassays, the system operates in a simplified half-sandwich format, eliminating the need for secondary antibodies, enzymes, or fluorescent tags. TSH detection is achieved through electrostatic interaction between the positively charged redox probe, hexaammineruthenium(III) chloride (Ru(III)), and the negatively charged TSH protein. This interaction leads to signal amplification by increasing the redox current through electrostatic attraction between the positively charged Ru(III) complex and the negatively charged TSH molecules. Electrochemical measurements performed using square wave voltammetry (SWV) exhibited a linear response over a concentration range of 0.01–40 mIU/L, with a correlation coefficient (R2) of 0.9966. The sensor achieved the empirical limit of detection (LOD) of 0.01 mIU/L. The proposed immunosensor demonstrated high specificity, minimal cross-reactivity, and excellent reproducibility. This platform provides strong signal amplification, label-free simplicity, and operational portability that make it a promising tool for point-of-care CHT screening in decentralized or low-resource clinical settings.