Cyclic electron flows and the initial reaction process of the photoinhibition in the photosystem II

略語 / p1 要旨 / p4 序論 / p9 第I章 PSII内環状電子移動の解析 / p21 　緒言 / p21 　I-1.実験材料及び実験方法 / p25 　I-2.実験結果 / p42 　I-3.考察 / p69 第II章 PSII光阻害反応初期過程の解析 / p77 　緒言 / p77 　II-1.実験方法 / p83 　II-2.実験結果 / p89 　II-3.考察 / p110 　本研究の総括 / p121 参考論文 / p123 付録 / p129 　1.PSII粒子の調製方法 / p129 　2.集光性蛋白質の除去法 / p131 　3.水分解系の除去 / p132 　4.非ヘム鉄の除去 / p133 　5.非ヘム鉄のZn²⁺への置換 / p134 　6.325nmに見られる吸光度変化モデル / p135 　7.レーザーフラッシュフォトリシス法で測定された緩和過程の解析プログラム / p137 謝辞 / p147 参考文献 / p148広島大学(Hiroshima University)博士(学術)Sciencedoctora

Signal amplification in electrochemical detection of buckwheat allergenic protein using field effect transistor biosensor by introduction of anionic surfactant

AbstractFood allergens, especially buckwheat proteins, sometimes induce anaphylactic shock in patients after ingestion. Development of a simple and rapid screening method based on a field effect transistor (FET) biosensor for food allergens in food facilities or products is in demand. In this study, we achieved the FET detection of a buckwheat allergenic protein (BWp16), which is not charged enough to be electrically detected by FET biosensors, by introducing additional negative charges from anionic surfactants to the target proteins. A change in the FET characteristics reflecting surface potential caused by the adsorption of target charged proteins was observed when the target sample was coupled with the anionic surfactant (sodium dodecyl sulfate; SDS), while no significant response was detected without any surfactant treatment. It was suggested that the surfactant conjugated with the protein could be useful for the charge amplification of the target proteins. The surface plasmon resonance analysis revealed that the SDS-coupled proteins were successfully captured by the receptors immobilized on the sensing surface. Additionally, we obtained the FET responses at various concentrations of BWp16 ranging from 1ng/mL to 10μg/mL. These results suggest that a signal amplification method for FET biosensing is useful for allergen detection in the food industry

光合成光化学系IIにおける環状電子移動と光阻害反応初期過程

略語 / p1 要旨 / p4 序論 / p9 第I章 PSII内環状電子移動の解析 / p21 　緒言 / p21 　I-1.実験材料及び実験方法 / p25 　I-2.実験結果 / p42 　I-3.考察 / p69 第II章 PSII光阻害反応初期過程の解析 / p77 　緒言 / p77 　II-1.実験方法 / p83 　II-2.実験結果 / p89 　II-3.考察 / p110 　本研究の総括 / p121 参考論文 / p123 付録 / p129 　1.PSII粒子の調製方法 / p129 　2.集光性蛋白質の除去法 / p131 　3.水分解系の除去 / p132 　4.非ヘム鉄の除去 / p133 　5.非ヘム鉄のZn²⁺への置換 / p134 　6.325nmに見られる吸光度変化モデル / p135 　7.レーザーフラッシュフォトリシス法で測定された緩和過程の解析プログラム / p137 謝辞 / p147 参考文献 / p148広島大学(Hiroshima University)博士(学術)Sciencedoctora

光合成光化学系IIにおける環状電子移動と光阻害反応初期過程

略語 / p1 要旨 / p4 序論 / p9 第I章 PSII内環状電子移動の解析 / p21 　緒言 / p21 　I-1.実験材料及び実験方法 / p25 　I-2.実験結果 / p42 　I-3.考察 / p69 第II章 PSII光阻害反応初期過程の解析 / p77 　緒言 / p77 　II-1.実験方法 / p83 　II-2.実験結果 / p89 　II-3.考察 / p110 　本研究の総括 / p121 参考論文 / p123 付録 / p129 　1.PSII粒子の調製方法 / p129 　2.集光性蛋白質の除去法 / p131 　3.水分解系の除去 / p132 　4.非ヘム鉄の除去 / p133 　5.非ヘム鉄のZn²⁺への置換 / p134 　6.325nmに見られる吸光度変化モデル / p135 　7.レーザーフラッシュフォトリシス法で測定された緩和過程の解析プログラム / p137 謝辞 / p147 参考文献 / p148博士(学術)博士(学術)広島大

Effect of human serum on the electrical detection of amyloid-β fibrils in biological environments using azo-dye immobilized field effect transistor (FET) biosensor

As amyloid-β peptide 1–42 (Aβ42) was found to be an emerging and important biomarker for Alzheimer's disease, the detection of this peptide in biological samples such as human serum (HS) has become very important for evaluating the potential disease state and determining the appropriate treatment. In this study, we developed an electrical analysis strategy based on a field effect transistor (FET) biosensor as a simple and reliable technique for confirming the presence of Aβ42 aggregates (fibrils) in biological samples. By utilizing Congo red immobilized on the FET gate surface as a biorecognition element, we observed remarkable sensitivity and specificity for detecting Aβ42 fibrils. Furthermore, we optimized the procedure to minimize the interference of abundant human serum albumin for the detection system using HS samples. The optimized system of Congo red-immobilized FET enables measurement of Aβ42 fibrils in the 100-pM level in HS samples, which is lower than its clinical concentration. The FET device can be applied as a biosensing system for mass and routine screening of peptide biomarkers related to Alzheimer's disease. Keywords: Field effect transistor biosensor, Amyloid beta fibrils, Alzheimer's disease, Human serum albumin, Albumin-amyloid beta complexe

Field Effect Transistor Biosensor Using Antigen Binding Fragment for Detecting Tumor Marker in Human Serum

Detection of tumor markers is important for cancer diagnosis. Field-effect transistors (FETs) are a promising method for the label-free detection of trace amounts of biomolecules. However, detection of electrically charged proteins using antibody-immobilized FETs is limited by ionic screening by the large probe molecules adsorbed to the transistor gate surface, reducing sensor responsiveness. Here, we investigated the effect of probe molecule size on the detection of a tumor marker, α-fetoprotein (AFP) using a FET biosensor. We demonstrated that the small receptor antigen binding fragment (Fab), immobilized on a sensing surface as small as 2–3 nm, offers a higher degree of sensitivity and a wider concentration range (100 pg/mL–1 μg/mL) for the FET detection of AFP in buffer solution, compared to the whole antibody. Therefore, the use of a small Fab probe molecule instead of a whole antibody is shown to be effective for improving the sensitivity of AFP detection in FET biosensors. Furthermore, we also demonstrated that a Fab-immobilized FET subjected to a blocking treatment, to avoid non-specific interactions, could sensitively and selectively detect AFP in human serum

Immobilization of Target-Bound Aptamer on Field Effect Transistor Biosensor to Improve Sensitivity for Detection of Uncharged Cortisol

Field effect transistor (FET) biosensors are capable of detecting various biomolecules, although challenges remain in the detection of uncharged molecules. In this study, the detection of uncharged cortisol was demonstrated by interfacial design using a technique to immobilize target-bound aptamers. The target-bound aptamers, which formed a higher-order structure than target-unbound aptamers, expanded the distance between adjacent aptamers and reduced the steric hindrance to the conformational change. The density-controlled aptamers efficiently induced their conformational changes with the cortisol binding, which resulted in the improvement of the sensitivity of FET biosensors