Aptamer-functionalized plasmonic hot- carrier biosensors for 17β-estradiol

다국어 초록 (Multilingual Abstract)

The development of highly sensitive and reliable biosensing platforms is essential for the detection of trace-level biomarkers in clinical and environmental applications. In this study, we present a solid-state plasmonic hot-carrier biosensor for the ultrasensitive detection of 17β-estradiol （E2）, a potent endogenous estrogen hormone involved in the regulation of the endocrine system. The proposed device is based on an Au/Si/Au optoelectronic architecture integrated with gold nanoparticles （GNPs） functionalized through a biorecognition interface involving antibody and aptamer components. Under resonant optical excitation, localized surface plasmon resonance （LSPR） in the GNPs generates energetic charge carriers via non-radiative decay processes, which can be injected across the Au/Si interface to produce a measurable photocurrent. The presence of E2 modulates the interfacial electronic environment and influences carrier transport, resulting in a concentration-dependent photocurrent response. The effects of nanoparticle distribution, plasmonic field enhancement, and interfacial energetics on device performance are systematically investigated. The proposed biosensor demonstrates ultrasensitive detection with a limit of detection of approximately 13 aM, indicating its capability for trace-level hormone sensing. These results indicate that plasmonic hot-carrier injection can serve as an effective transduction mechanism for label-free biosensing, enabling the development of miniaturized optoelectronic sensing platforms.

목차 (Table of Contents)

• CHAPTER 1. INTRODUCTION 1
• CHAPTER 2. BACKGROUND THEORIES 4
• 2.1. Localized Surface Plasmon Resonance 4
• 2.1.1. Theory of LSPR 4
• 2.1.2. Electromagnetic Field Enhancement Near Metal Nanostructures 5
• 2.1.3. Hotspot Formation at All-metallic Nanoparticle-Film Interfaces 6
• 2.2. Hot Carrier Generation 8
• 2.2.1. Non-radiative Decay and Hot-carrier Generation 8
• 2.2.2. Energy Distribution of Hot Electrons and Hot Holes 9
• 2.2.3. Relaxation and Recombination Processes 9
• 2.3. Metal–Semiconductor Contact 12
• 2.3.1. Schottky Barrier 12
• 2.3.2. Fermi Level Pinning 14
• 2.3.3. Internal Photoemission Mechanism 15
• 2.4. Optoelectronic biosensor 16
• CHAPTER 3. MATERIALS, DEVICES AND EXPERIMENTAL TECHNIQUES 19
• 3.1. Overview of Experiment 19
• 3.2. Chemicals and Reagents 20
• 3.3. Experimental Apparatus and Instrumentation 20
• 3.4. Experimental Processes 21
• 3.4.1. Fabrication of Electrodes 21
• 3.4.2. Immobilization of Thiol-Modified Aptamers 21
• 3.4.3. Synthesis of Gold Nanoparticles 22
• 3.4.4. Preparation of E2-Antibody-Conjugated GNPs 23
• 3.4.5. Protocols for 17β-Estradiol Detection 23
• CHAPTER 4. RESULTS AND DISCUSSION 25
• 4.1. Formation of GNP-Ab-E2 Complex and Its Characterization 25
• 4.2. Photocurrent Response to E2 Concentration 27
• 4.3. Reproducibility and Selectivity Analysis 30
• 4.4. Real Sample Analysis 31
• CONCLUSION AND OUTLOOK 34
• REFERENCES 35
• ACKNOWLEDGEMENT 39