An electrochemical H₂O₂ sensor was developed using an alginate/water-soluble prussian blue/reduced graphene oxide (A/s-PB/rGO) composite on carbon screen printed electrodes for use in bioapplications. Carbon screenprinted working electrodes were modified with A/s-PB, A/rGO, and A/s-PB/rGO composite solutions by in situ gelation. The composites were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The cyclic voltammetric measurements made using the electrode modified by A/s-PB/rGOs showed improved electrochemical reaction and stability over the A/s-PB and A/rGO modified electrodes. A two-electron transfer process is indicated at the modified electrode surface. The oxidation current showed a detection limit of 4 mM (S/N = 3) and linear range of 4–28 mM. The A/s-PB/rGO modified electrode provides a tool for high-sensitivity (2.7 μA·mM^-1·cm^-2) and stable H₂O₂ analyses with a low limit of detection. Development of biosensor-based modified electrodes is important for biomedical and environmental applications.

다양한 바이오 응용에서 중요한 측정 인자인 과산화 수소(H₂O₂) 센서를 개발하기 위하여, 알지네이트(A) 용액에 수용성 프러시안 블루(s-PB), 그리고 환원된 그래핀 옥사이드(rGO)를 분산시켜 전극 소재를 만들었고 탄소 스크린 프린트 전극에 복합 용액을 젤화 과정을 통해 전극에 고정시켰다. 젤화 과정에서 전극 소재에 남아 있는 염을 제거하기 위하여 충분히 수세를 한 후 실온에서 건조하였다. 전극 소재의 특성은 푸리에 변환 적외선 (FTIR), 전계방출 주사 전자 현미경(FE-SEM)으로 조사하였다. A/s-PB/rGO 전극을 이용한 순환 전류(CV) 측정 결과를 통해 전극으로써 우수한 전기 화학 반응, 안정성, 재현성을 확인하였고, 미분 펄스 볼타 그램(DPV)으로 측정한 산화 전류는 4 mM(S/N = 3)의 검출 한계와 높은 감도(2.7 μA · mM^-1· cm^-2)를 나타내었다. 전기화학적 센서 기반의 전극 개발은 의학 및 환경 응용 분야에서 매우 중요하게 활용될 것으로 판단된다.

Keywords: A/s-PB/rGO modified electrode, A/s-PB modified electrode, A/rGO modified electrode, electrochemical sensor, hydrogen peroxide

Hydrogen peroxide (H₂O₂), as a kind of reactive oxygen species, is an important signaling molecule in the biological processes associated with many diseases,¹ as well as in food manufacturing,² pharmaceutical,³ and environmental applications. ⁴ Electrochemical biosensors have been used for medical, biological and biotechnological applications such as real-time electrochemical neurotransmission monitoring, H₂O₂ and cellbased biosensing, and antibody fragments or antigens used to monitor binding.⁵ Development of electrochemical sensors for H₂O₂ detection has focused on the enhanced electrochemical sensitivity of electrodes modified by nanomaterials such as one-dimensional carbon nanotubes (CNTs), two-dimensional graphene, or reduced graphene oxide (rGO) and prussian blue (PB) on bare gold and glassy carbon electrodes.^6-8 In recent years, electrodes modified using two-dimensional graphene or rGO have also been investigated because of their unique properties such as fast electron transport, good biocompatibility, high thermal conductivity, and electro-activity for redox reactions. ⁹ Two-dimensional graphene modified electrodes used as electrochemical sensors have enhanced ability to detect the electrocatalytic activity of small biomolecules such as enzymes, dopamine, H₂O₂ and nicotinamide adenine dinucleotide (NADH).¹⁰ The physical and electrochemical properties of rGO, such as carbon structures, defects, and functional groups on the surface have been used in electrochemical applications.¹¹ Studies have shown electrochemically rGO modified electrodes used for electrochemical sensing of nitric oxide¹² and detection of tyrosine¹³ and H₂O₂.¹⁴
Researchers have reported high sensitivity and detection limits using electrodes modified by rGO/PB composites for glucose, ¹⁵ dopamine, and H₂O₂ sensing,¹⁶ spontaneous deposition of PB on rGO-gold nanoparticle composites,⁷ and other compounds. ¹⁷ PB or ferric ferrocyanide (Fe4[Fe(CN)₆]₃) has been investigated for use in electrochromic applications,¹⁸ secondary batteries,¹⁹ chemical and biological sensors,²⁰ and hydrogen storage.²¹ The electroactive layers of PB deposited onto the surface of an electrode has been improved by forming composites of PB with different nanomaterials.²⁰ However, PB is insoluble in most common solvents and dispersion of PB into a solvent is needed to make composites with various nanomaterials or polymers. A water-soluble form of PB (s-PB; C₆Fe₂KN_6·xH₂O) is known as an inorganic pigment containing ferric ferrocyanide and has been used to track transplanted cells such as mesenchymal stem cells²² and monitor iron oxide particle labeling dilution through cell division.²³ Alginate/CNT composite modified electrodes formed by in situ gelation have been used to monitor caffeic acid derivatives. The alginate forms an interconnected CNT network on a modified electrode. ²⁴ Sodium alginate (SA) is a natural polysaccharide used for the removal of pollutants from water and is an excellent natural adsorbent.²⁵ SA as immobilized agent was formatted the water-insoluble alginate hydrogel with hydrophobicity by binding of Na+ ions dissociated from the polysaccharides and divalent cations such as Ca²⁺.²⁶ The sodium alginate was converted to calcium alginate gel and the alginate composite was obtained by washing. Other researchers have reported that alginate and rGO composites become hydrophilic and the rGO can be well dispersed.²⁵
In this study, we develop A/s-PB/rGO composite modification of a carbon screen printed electrode (SPE) for the electrochemical sensing of H₂O₂. The A/s-PB/rGO modified electrode is used in cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies as a H₂O₂ biosensor and its suitability as an electrode material was assessed.