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Sains Malaysiana 55(9)(2026): 1462-1475
http://doi.org/10.17576/jsm-2026-5509-05
A Dicysteinyl Tripeptide-Based Electrochemical Sensor for
Highly Selective and Stable Detection of Mercury(II) Ions
(Sensor Elektrokimia Berasaskan Dicysteinyl Tripeptide untuk Pengesanan Ion Merkuri(II) yang Sangat Selektif dan Stabil)
NURULHAIDAH DAUD1,2,*, NURUL IZZATY HASSAN3 & CHIN SIEW XIAN1
1National PERMATA@pintar Centre, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor,
Malaysia
2Nano Semiconductor Technology, Mimos Berhad, Technology Park
Malaysia, 57000
Kuala Lumpur, Malaysia
3Chemistry Department, Faculty
of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
Received: 24 February 2026/Accepted: 18 August 2026
*Corresponding author; email: nurulhaidah@ukm.edu.my
Abstract
Global
industrialization has made it necessary to create cheap, quick ways to measure mercury(II) ions (Hg2+) in water systems. This
study presents a dicysteinyl tripeptide of NH2-Cysteine-Alanine-Cysteine-COOH
(CAC)- based electrochemical sensor designed for the highly selective and
stable detection of Hg2+ ions. The modified electrode was fabricated
by the immobilization of the CAC-tripeptide and multi-walled carbon nanotubes (MWNTs)
within a Nafion polymer matrix onto a platinum
electrode (Pt). Molecular dynamics (MD) simulations confirmed that Hg2+ chelation via dicysteinyl thiol groups rigidifies the
CAC tripeptide matrix into a structurally stable, low-flexibility conformation.
This CAC/MWNTs/Nafion/Pt electrode modification
provided a high surface area and superior charge transport capacity, resulting
in good sensitivity. Analytical validation demonstrated a linear response range
of 10 to 100 nM, with a limit of detection (LOD) of
7.9 nM, effectively exceeding the World Health
Organization (WHO) safety criterion of 10 nM. With a
relative standard deviation (RSD) of 3.1% (n = 7) at 100 nM Hg2+, the modified electrode demonstrated great precision.
Moreover, the biosensor exhibited excellent reproducibility and substantial
long-term stability, maintaining 85% of its initial electrochemical response
after a three-week duration. Selectivity studies showed that most species were
quite resistant to competing metal ions, with only Cu2+ and Ag+ causing modest problems. Based on this result, the immobilization of the
CAC-tripeptide and multi-walled carbon nanotubes (MWNTs) within a Nafion polymer matrix onto a platinum electrode development
seems like a promising early, easily accessible option for environmental water
quality monitoring in real time.
Keywords: Dicysteinyl tripeptide; electrochemical sensor; mercury(II) ion; MWNTs
Abstrak
Perindustrian global telah menjadikan pembangunan kaedah pengukuran ion merkuri(II) (Hg2+) yang murah dan pantas di dalam sistem air sebagai satu keperluan. Kajian ini membentangkan penderia elektrokimia berasaskan tripeptida disisteinilNH2-Sisteina-Alanina-Sisteina-COOH (CAC)
yang direka untuk pengesanan ion Hg2+ yang sangat selektif dan stabil. Elektrod terubah suai telah difabrikasi melalui imobilisasi tripeptida CAC dan tiub nano karbon berdinding pelbagai (MWNTs) di dalam matriks polimer Nafion ke atas elektrod platinum (Pt). Simulasi dinamik molekul (MD) mengesahkan bahawa pengkelatan Hg2+ melalui kumpulan tiol disistenil menegarkan matriks tripeptide CAC menjadi konformasi fleksibel rendah yang stabil dari segi struktur. Pengubahsuaian CAC/MWNTs/Nafion/Pt elektrod ini menyediakan luas permukaan yang tinggi dan kapasiti pengangkutan cas yang unggul, yang menghasilkan kepekaan yang baik. Pengesahan analitikal menunjukkan julat tindak balas linear antara 10 hingga 100 nM dengan had pengesanan (LOD) sebanyak 7.9 nM, sekali gus berjaya melepasi kriteria keselamatan Pertubuhan Kesihatan Sedunia (WHO) iaitu 10 nM. Dengan sisihan piawai relatif (RSD) sebanyak 3.1% (n = 7) pada 100 nM Hg2+, elektrod terubah suai tersebut menunjukkan kejituan yang tinggi. Selain itu, penderia kimia ini menunjukkan kebolehulangan yang cemerlang dan kestabilan jangka panjang yang teguh, dengan mengekalkan 85% daripada tindak balas elektrokimia asalnya selepas tempoh tiga minggu.
Kajian selektiviti menunjukkan bahawa kebanyakan spesies adalah agak rintang terhadap gangguan ion logam pesaing dengan hanya Cu2+ dan Ag+ yang menyebabkan gangguan sederhana. Berdasarkan keputusan ini, pembangunan elektrod terubah suai melalui imobilisasi tripeptida CAC
dan tiub nano karbon berbilang dinding (MWNTs) di dalam matriks polimer Nafion ke atas elektrod platinum dilihat sebagai satu pilihan awal yang berpotensi dan mudah dicapai bagi pemantauan kualiti air alam sekitar secara masa nyata.
Kata kunci:
Ion merkuri (II); MWNTs; penderia elektrokimia; tripeptida disisteinil
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