Comparison of treatment outcomes and complications of coil embolization in elderly and very elderly patients with cerebral aneurysms: a propensity score matching analysis.

PURPOSE: This single center study aims to compare the treatment outcomes and procedure-related complications of coil embolization in elderly patients (60-79 years) and very elderly patients (aged 80 years or older) with cerebral aneurysms. METHODS: Data was collected from 504 elderly patients aged 60 years or older who underwent coil embolization for intracranial aneurysms from 2018 to 2021. The study evaluated patient-related and anatomical factors and assessed various outcomes, comparing results between groups using statistical analysis and propensity score matching. RESULTS: A total of 503 cerebral aneurysms were analyzed from individuals aged 60-79 years (n = 472) and those aged 80 years or older (n = 31). The majority of the aneurysms were unruptured with an average size of 3.5 mm in height and 3.4 mm in width. The patients were compared using 1:1 propensity score matching, and no significant differences were found in factors other than age and aortic elongation. Logistic analysis revealed that being over 80 years old and having a severe aortic arch elongation were identified as risk factors for procedure-related events in both total and unruptured cases. CONCLUSIONS: The study compared coil embolization treatment for cerebral aneurysms in patients aged 60-79 and over 80, finding no significant difference in treatment outcomes except for procedure-related events. Procedure-related events were associated with severe aortic arch elongation and being over 80 years old. Coil embolization can be considered safe and effective for patients over 80, but further trials are needed for accurate conclusions.

Epidemiological Study of Malignant Gliomas in Korea Using Nationwide Dataset from 2007 to 2017.

BACKGROUND: The purpose of the study was to investigate the incidence, prevalence, and survival of malignant gliomas (MGs) using population-based Korean National Health Insurance Database (NHID) data. METHODS: Using the Korean NHID, we identified patients with MG as C71 codes in KCD 5-7 according to ICD-10 from January 1, 2007 to December 31, 2017. Epidemiological characteristics of MG, including annual incidence, prevalence, mortality rates, and survival rates, were collected and analyzed according to socioeconomic state (SES) and treatments received. RESULTS: We identified 45,066 newly diagnosed-MG patients from 2007 to 2017, for an age-adjusted incidence of 7.47 per 100,000 people. The mean age at diagnosis was 54 years. The male to female ratio was 1.11. Mortality and survival probability were analyzed among total subjects and in subgroups. The mortality rates were lower in female than that of male patients (hazard ratio, 0.69; 95% confidence interval, 0.67-0.71), and in younger age population and in higher income group. Patients operated had a slightly higher survival rate. The 1-, 3-, 5-, and 10-year survival rates were estimated at 63.4%, 46.2%, 39.4%, and 34.8%, respectively. This is the first population-based study to determine the incidence and prevalence of MG according to epidemiological characteristics in Korea using NHID. CONCLUSION: Our study found that female sex and high SES were factors that significantly lowered the mortality rate in MG, and younger groups and operated patients showed significantly higher survival rates.

Effective use of balloon guide catheters in reducing incidence of mechanical thrombectomy related distal embolization.

BACKGROUND AND PURPOSE: The clinical benefit of endovascular stroke therapy has been demonstrated in several prospective randomized trials. However, in a relevant percentage of patients, mechanical thrombectomy bears the risk of causing new infarction in initially unaffected vascular territories through thrombus fragmentation and migration of clot debris. The goal of this study was to evaluate the use of the balloon guide catheter (BGC) to effectively achieve flow arrest and thrombus aspiration during the intervention to avoid distal embolization. METHODS: A retrospective study was performed in 139 patients between October 2010 and May 2016 to analyze occlusions in the middle cerebral artery (MCA) or internal carotid artery (ICA) by using a stent retriever with a BGC (n = 73) or a non-BGC (n = 66). The following data were collected: patient age and gender, along with history of diabetes mellitus, hypertension, atrial fibrillation, smoking, obesity, dyslipidemia, and previous ischemic stroke. Data on procedure time, number of passes, and angiographic findings were also collected. The final reperfusion score was rated based on the Thrombolysis in Cerebral Infarction (TICI) grading scale. Successful recanalization was defined as TICI 3 or 2b. RESULTS: A total of 139 patients underwent mechanical thrombectomy with the stent retriever. Of the 139 patients, 73 (52.5%) underwent placement of a BGC. The mean age was 65.8 ± 13.5 years, and the median National Institutes of Health Stroke Scale (NIHSS) score was 11. The average initial NIHSS score was lower in the BGC group compared with the non-BGC group (mean, 11.2 ± 5.6 vs. 13.2 ± 5.6; P = 0.03). Patients with BGC had fewer incidences of previous ischemic stroke (12.3% vs. 28.8%; P = 0.01). The numbers of passes were similar between the two groups. The procedure time (99 ± 49.4 min vs. 124 ± 72.2 min; P = 0.02) and the time from onset of symptoms to procedure end (302 ± 102 min vs. 357.2 ± 136.1 min; P = 0.009) were shorter in the BGC group. TICI 3 or 2b recanalization scores were higher in the BGC group compared to the non-BGC group [63/73, 86.3% vs. 48/66, 72.7%; odds ratio (OR), 0.6; 95% confidence interval (CI), 0.2-1.4; P = 0.04]. Importantly, distal embolization was less frequent in the BGC group (5/73, 6.8% vs. 21/66, 31.8%; OR, 6.3; 95% CI, 2.2-18.0; P < 0.001). CONCLUSIONS: The risk of distal embolization was significantly decreased with the use of a BGC.

Risk factors for cerebral infarction and cerebrovascular stenosis in antiphospholipid antibody-positive patients: A retrospective single-center study with propensity score matching analysis.

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by the presence of antiphospholipid antibodies (aPLA), such as anticardiolipin (aCL), anti-ß2-glycoprotein I (aß2GPI), or lupus anticoagulant (LA). Although cerebrovascular events are commonly associated with APS, comprehensive studies on risk factors for cerebral infarction in aPLA-positive patients remain sparse. In this retrospective single-center study, data from 9844 patients tested for aPLA between January 2017 and March 2023 were analyzed. A total of 647 aPLA-positive patients were included, with assessments of various factors including age, gender, hypertension, diabetes, dyslipidemia, smoking history, and cardiac disease. Propensity score matching was employed to create 2 matched groups of 202 patients each, comparing those with and without cerebral infarction. Logistic regression analyses were conducted to identify risk factors for cerebral infarction and progression of cerebrovascular stenosis. The mean age of the study cohort was 65.8 years, with 60% being male. LA was positive in 95.2% of the cases, aCL in 8.8%, and aß2GPI in 5.3%. High-risk aPLA profiles were identified in 7.1% of the cases. In the cerebral infarction group, both smoking history and aCL positivity were significantly associated with an increased risk (OR = 1.543; 95% CI: 1.020-2.334; P = .040 and OR = 3.043; 95% CI: 1.426-6.491; P = .040, respectively). Male gender and posterior circulation involvement were significant risk factors for exacerbation of cerebrovascular stenosis (OR = 3.73; 95% CI: 1.16-16.69; P = .046 and OR = 5.41; 95% CI: 1.80-16.05; P = .002, respectively). Smoking history and aCL positivity are prominent risk factors for cerebral infarction in aPLA-positive patients, while male gender and involvement of the posterior circulation emerge as significant risk factors for the progression of cerebrovascular stenosis. Further comprehensive prospective studies are necessary to deepen understanding of aPLA-related cerebrovascular diseases.

A novel role for Gadd45α in base excision repair: modulation of APE1 activity by the direct interaction of Gadd45α with PCNA.

The growth arrest and DNA damage inducible, alpha (Gadd45α) protein regulates DNA repair by interacting with proliferating cell nuclear antigen (PCNA). Our previous study suggested a potential role for Gadd45α in the base excision repair (BER) pathway by affecting apurinic/apyrimidinic endonuclease 1 (APE1) protein in addition to its accepted role in nucleotide excision repair (NER). Here, we investigated whether the interaction of Gadd45α with PCNA affects APE1 activity. To address this issue, we used a siRNA directed to Gadd45α and a form of Gadd45α with a mutation to the predicted site of PCNA binding. There was a reduction of APE1 activity in cells transfected with the Gadd45α siRNA. Furthermore, the interaction of Gadd45α with PCNA and APE1 was lower in cells transfected with mutant Gadd45α compared with cells transfected with wild-type Gadd45α. Indeed, we observed that the APE1 activity in the Gadd45α-interacting complex was significantly lower in cells that overexpress mutant Gadd45α compared with cells that overexpress wild-type Gadd45α. We conclude that the PCNA binding site on Gadd45α plays a critical role in modulating the interaction with PCNA and APE1, affecting BER activity. These results provide novel insights into the mechanisms by which BER activity is modulated, although the interaction of Gadd45α with APE1 needs to be clarified.

Analysis of Factors Affecting Good Neovascularization After Indirect Bypass Surgery: A Two-center Retrospective Study.

OBJECTIVE: The purpose of this study was to analyze factors affecting good neovascularization after indirect bypass surgery. METHODS: From August 2000 to July 2020, postoperative image results and medical records of 132 patients (159 hemispheres) who underwent EDAS of indirect bypass surgery at two institutions were reviewed retrospectively. Based on DSA results, angiogenesis after indirect bypass was divided into "good" or "poor" according to the Matsushima criteria. STA flap length affecting GPN were analyzed in the entire group (n = 159) and a MMD group (n = 134). RESULTS: In the entire group, GPN after EDAS was observed in 94 (59.1%) hemispheres. Age, MMD, hypertension, and bone flap size were identified as significant factors in univariate analysis. Also, in the MMD group, 86 (64.2%) hemispheres showed GPN. Hypertension and bone flap size were significant factors in both univariate and multivariate analyses. Cutoff values of bone flap size and GPN were 47.91 cm2 in the entire group and the MMD group. CONCLUSIONS: In all patients who received EDAS, good postoperative neovascularization was significant in those with a young age, MMD, without hypertension, and large bone flap size. No hypertension and large bone flap size were meaningful factors in the MMD group. AUROC showed that an appropriate bone flap size was 47.91 cm2. However, a further controlled prospective study is needed.

A Comparison of Clinical and Radiological Outcomes Between Target 360 Nano and Microplex Hypersoft 3D Used as Finishing Coil.

AIM: To compare the clinical outcomes of Target 360 nano (TG) and Microplex hypersoft 3D (MH) used as a finishing coil (FC). MATERIAL AND METHODS: From January 2018 to December 2020, we retrospectively reviewed 243 coil embolization procedures performed using TG (n=152) and MH (n=91) coils of 1mm x 2 cm the same size as FC. Further, the clinical and radiographic results were compared by matching the propensity score between the two groups. RESULTS: There were no statistically significant differences in the clinical and angiographic results of the two coils after the propensity score matching. Successful occlusion was 89% and 86.8% and FC insertion failure was 20.9% and 28.6%. There were no differences in procedure-related complications and recurrence between the groups during the eight months follow-up period (3.3% versus 4.4% and 4.4% versus 3.3%, respectively). We also compared two subgroups of failed FC insertion (19 of TG and 26 of MH). The number of angled catheters was significantly higher in the failed TG group than in the failed MH group. CONCLUSION: There was no statistically significant difference between the clinical and radiological outcomes of TG and MH used as FC. However, in the FC insertion failure subgroups, the number of angled catheters was significantly higher in the TG failed group than in the MH failed. It was experimentally confirmed that the angle change of microcatheter tip with a large angle was large; however, further studies are required.

Is a small coil more effective as a finishing coil for the embolization of intracranial aneurysms? Outcomes using GALAXY G3™ MINI micro-coils as finishing coils in a single center.

OBJECTIVE: The purpose of this study was to compare the outcomes of coil embolization using a 0.009 inches primary outer diameter coil as finishing coil (FC) to that of 0.01 inches. METHODS: From February and August 2020, 131 aneurysms that performed coil embolization using FC with a second loop diameter of 1 mm, were reviewed retrospectively, conducting propensity score matching and logistic regression analysis. Angiographic results such as, occlusion grade, packing density, failure and event were compared between 0.009 inches coil of GALAXY G3™ MINI microcoil (n = 54) and 0.01 inches coils (n = 77). RESULTS: There were no statistically significant differences between two groups, but more events occurred in the 0.009 group. (Odds ratio, 3.65; 95% CI, 1.06-12.55; P = 0.031) In the results of coil embolization, successful occlusion occlusion (complete occlusion and residual neck) was identified more in the 0.01 group. After propensity score matching, the variables in each group were similar, but the successful occlusion was higher in the 0.01 group as in the total population. Events tended to occur more frequently in the 0.009 inch group, and logistic regression analysis showed slightly higher events in the angled microcatheter. (48.3% versus 76.9%., P = 0.075), Also, the 0.009 inch FC is an independent risk factor. (Odds ratio, 3.84; 95% CI, 1.07-13.80; P = 0.039). CONCLUSIONS: Using 0.01 inches coils as FC increased the packing density after the procedure, and showed more successful occlusion than using a 0.009 inches coil. The probability of unexpected events was observed more than three times in the 0.009 inch group.

Resistance profiling and molecular characterization of Staphylococcus aureus isolated from goats in Korea.

Staphylococcus aureus is among the most common zoonotic pathogens that cause foodborne illnesses worldwide. The main objectives of the current study were therefore to determine the antimicrobial susceptibility profiles of S. aureus isolated from goats in Korea and to investigate the molecular characteristics of identified methicillin-resistant S. aureus (MRSA). In the study, 481 S. aureus isolates (431 from the nasal cavity and 50 from carcass) were recovered from 1146 carcasses and nasal swabs between July 2018 and January 2019. Approximately 82% and 72.6% of nasal and carcass isolates, respectively, were resistant to at least one antimicrobial agent, with the highest rate of resistance to penicillin, followed by resistance to chloramphenicol and tetracycline. Relatively small proportions of the isolates were resistant to cefoxitin, clindamycin, and erythromycin. However, all S. aureus isolates were sensitive to linezolid, rifampin, and vancomycin. Six MRSA isolates were obtained, three each from the nasal cavity and carcass. MRSA isolates were of two sequence types (ST) (ST72 and ST398), three spa types (t664, t324, and t571), and two SCCmec types (IV and V). The ST72 MRSA isolates had identical PFGE profiles. In addition, ST72 MRSA-SCCmec IV isolates carried at least six staphylococcal leukotoxin- and enterotoxin-encoding genes (lukED, seg, sei, sem, sen, seo, and seq). The remaining ST398 isolate carried only the lukED gene and was additionally resistant to eight non-ß-lactam antibiotics. To the best of our knowledge, this is the first report of MRSA from goats in Korea. There is a possibility of transmission of MRSA from goat to human or contamination of food products. Therefore, regular microbiological investigation in goats, farms, and slaughterhouses is critical to determine the existence of virulent and multi-drug resistant (MDR) S. aureus and to implement preventive strategies.

Ferredoxin molecular thin film with intrinsic switching mechanism for biomemory application.

A biomemory device consisting of cysteine modified ferredoxin molecules which possess a memory effect via a charge transfer mechanism was developed. For achieving an efficient bioelectronic device, cysteine modified ferredoxin was developed by embodying cysteine residues in ferredoxin by site--directed mutagenesis method to directly coordinate with the gold (Au) surface without use of any additional linkers. The thin film formation of ferredoxin molecules on Au electrode is confirmed by surface plasmon resonance (SPR) spectroscopy and scanning tunneling microscope (STM). Cyclic voltammetry (CV) and open circuit potential amperometry (OCPA) methods were used to verify the memory switching characteristics of the fabricated device. The charge transfer between ferredoxin protein molecules and Au electrode enables a bi-stable electrical conductivity allowing the system to be used as a digital memory device. Data storage is achieved by applying redox voltages which are within the range of -500 mV. These results suggest that the proposed device has a function of memory and can be used for the construction of a nano-scale bioelectronic device.

Nanoscale film formation of recombinant azurin variants with various cysteine residues on gold substrate for bioelectronic device.

Nanoscale film fabrication of recombinant azurin variants with various cysteine residues on gold substrate was developed without any surface modification for bioelectronic device. We have modified azurin with different number of cysteine residues at its amino acid chain based on site-directed mutagenesis. The resulting recombinant protein, azurin, retained its original redox property in the same manner as native azurin. Recombinant azurin was immobilized on Au substrate by strong affinity between thiol of cysteine and gold. The orientations of recombinant azurin with various cysteine residues immobilized on the Au substrate were analyzed by fluorescence microscope, scanning tunneling microscope, and surface plasmon resonance. Our data revealed that binding activity of recombinant azurin with three cysteine residues on the Au substrate significantly increased in comparison to single residue azurin. Immobilization method of highly oriented recombinant azurin based on cysteine-modification could be useful for the nanoscale film fabrication of nanobiochip.

Cigarette Smoking Is Associated with Increased Risk of Malignant Gliomas: A Nationwide Population-Based Cohort Study.

The association between cigarette smoking and the risk of developing malignant glioma (MG) remains unclear. We aimed to evaluate this potential association in a large general population, using a well-established and validated longitudinal nationwide database. Using data from the Korean National Health Insurance System cohort, 9,811,768 people over 20 years old without any cancer history in 2009 were followed until the end of 2017. We documented 6100 MG cases (ICD-10 code C71) during the median follow-up period of 7.31 years. Current smokers had a higher risk of developing MG (HR = 1.22, CI: 1.13-1.32) compared with never-smokers, after adjusting for confounders. This association was stronger for those who smoked ≥ 20 cigarettes daily (HR = 1.50, CI: 1.36-1.64). Furthermore, having 30 or more pack-years of smoking over the course of one's lifetime was associated with an increased risk of developing MG in a dose-dependent manner, compared with never-smokers (HR = 1.31, CI: 1.16-1.48 for 30-39 pack-years of smoking; HR = 1.36, CI: 1.17-1.59 for 40-49 pack-years of smoking; HR = 1.68; CI: 1.44-1.95 for ≥ 50 pack-years of smoking). These results suggest that cigarette smoking may be associated with developing MG. Further prospective studies could help elucidate this association.

Fabrication of nano scaled protein monolayer consisting of cytochrome c on self-assembled 11-MUA layer for bioelectronic device.

The biomolecular/organic hetero-structure films (cytochrome c/11-mercapto-undecanoic acid) on gold substrates were controlled and fabricated with molecular level for developing valuable molecular electronic devices. Cytochrome c is a metalloprotein having redox property, which can be directly applicable to biomemory device as a active element. For efficient immobilization of the protein on the gold substrate, 11-mercapto-undecanoic acid (11-MUA) was used as a linker material between protein and inorganic substrate. The proposed nano scaled biomolecular/organic hetero-structure layer (cytochrome c/11-MUA) on gold surface was investigated by using surface plasmon resonance technique. The molecular morphology of the fabricated protein layer was confirmed by scanning tunneling microscopy. Electrochemical properties of fabricated biomolecular/organic hetero layer were verified using cyclic voltammetry. Their redox properties was sustained over 1000 cycles of cyclic voltametry. It proved that the fabricated film was a suitable platform for the bioelectronic device application.

Charge retention of self-assembled ferredoxin monolayer by the reduction-oxidation control for biomemory device.

The oxidation-reduction control to store charges in self-assembled ferredoxin layer was investigated by scanning electrochemical method. Micro sized spot arrays consisting of ferredoxin proteins which used as the storage element were formed on chemically modified gold coated glass by micro contanct printing method. The formation of ferredoxin array was confirmed by the atomic force microscopy. The charge store was investigated by external applied reduction potential to ferredoxin as a write function, and the stored reducing charge was measured as a read function of storage applications. In the reduction state, the stored charge was maintained for around 90 sec. This ferredoxin layer can be used as the molecular size information storage by applying the reducing potential and measuring the current flow when achieving the current of individual ferredoxin molecule.

Signal enhancement of surface plasmon resonance based immunosensor using gold nanoparticle-antibody complex for beta-amyloid (1-40) detection.

Numerous studies have indentified that beta-amyloid (1-40) in cerebrospinal fluid as a potential biomarker for Alzheimer's disease. In order for early detection of the Alzheimer's disease, an ultrasensitive diagnostic tool is required. In this study, an ultrasensitive surface plasmon resonance (SPR) based immunosensor for beta3-amyloid (1-40) was developed and its signal enhanced (1-40) with a gold (Au) nanoparticle-antibody complex. Antibodies to beta3-amyloid (1-40) were immobilized on the Au surface leading to a highly efficient immunoreaction due to the fact the paratope of the antibody faced in the opposite direction to the solid surface. The surface morphology of the bio-surface was investigated by using scanning tunneling microscopy (STM). The binding process of antibody fragments to the Au surface, target analytes, and Au nanoparticle-antibody complexes were monitored using SPR. The plot of SPR angle difference versus beta3-amyloid (1-40) concentration shows a linear correlation over a concentration range of nine orders of magnitude, having a detetion limit up to 1 fg/ml.

The Role of digital subtraction angiography in the ventricular spot sign on the computed tomography angiography.

OBJECTIVE: The spot sign on computed tomography angiography is little known about the relationship between the spot sign and the results of cerebral angiography We retrospectively analyzed the spot sign, digital subtraction angiography results, and other factors. MATERIAL AND METHODS: From December 2009 to May 2014, DSA was performed in 52 ICH patients with non-specific location or abnormalities on CTA findings. 26 of those patients, whose initial CTA showed the spot sign, were analyzed. Two groups, one with the spot sign in the ventricle (Group A) and others with the spot sign in another location (Group B) were statistically compared. RESULTS: The mean age of the study subjects was 46.9 years (range, 15 to 80 years) and the percentage of males was 53.8%. Thirteen of 26 patients had ICH without intraventricular hemorrhage, and 6 patients had co-existing IVH. In 17 cases, the DSA results were negative. Seven patients were diagnosed with pseudoaneurysms, and two cases showed developmental venous anomalies. Group A consisted of the 8 patients (30.8%) who showed the spot sign in a ventricle. The number of pseudoaneurysms was statistically significantly higher in Group A than in Group B (71.4% versus 28.6%; OR, 13.3; 95% CI, 1.7-103.8 P = 0.014). All three patients who underwent endovascular treatment were members of Group A (P = 0.022), whereas most (92.3%) of those in Group B underwent surgical evacuation. (P = 0.030). CONCLUSION: When CTA shows the spot sign in a ventricle, it is a clue that an existing underlying vascular lesion requires endovascular treatment.

Successful Mechanical Thrombectomy Using Solumbra Technique In a 35-year-old Man With Achondroplasia: a case report.

BACKGROUND: Achondroplasia is one of the most common types of dwarfism and is inherited as an autosomal dominant disease. The patients with achondroplasia suffer from various complications such as craniofacial, central nervous system, spinal, respiratory and cardiac anomalies. CASE DESCRIPTION: We report a case of a 35-year-old man with achondroplasia who visited the emergency room with right hemiplegia and aphasia within 6 hours after onset. An Initial CT angiography showed the total occlusion of a left internal cerebral artery due to the thrombus. We treated the patient with endovascular thrombectomy using "Solumbra technique" with balloon guiding catheter. The procedure was successful and result was completely recanalized with Thrombolysis in Cerebral Infarction (TICI) scale 3 and the weakness also improved from grade II to grade IV. CONCLUSION: Acute ischemic stroke patients with achondroplasia could be treated with mechanical thrombectomy.

Feasibility of Using Neck Extension to Overcome a Difficult Aortic Arch and Gain Access to the Carotid Artery.

OBJECTIVE: The purpose of this study was to investigate neck movement and various conditions of the aortic arch that may hinder access to the carotid artery during neurointerventional procedures. METHODS: We reviewed 230 patients who underwent internal carotid artery angiography between February 2016 and October 2016. Use of a Davis catheter (DC) was first attempted and if not possible, movement (right, left, flexion, and extension) of the patient's head was tried before catheter exchange. We analyzed the success rate after neck motion in relation to various aortic arch factors. RESULTS: Only extension of the patient's neck was effective. Of the 209 patients with right side angiography, 23 had failed access with a DC, but neck extension was effective in 3 patients (13%). Failure to insert a DC was significantly correlated with age, male sex, acute angle, arch elongation, aortic calcification, and carotid artery angulation on the right side, whereas access was not gained in 24 out of 208 patients who underwent left side angiography, and neck extension was successful in 7 patients (29.2%). Also, significant factors determining the catheter exchange were age, male sex, acute angle, arch elongation, and aortic calcification.In the DC access failure group, neck extension was significantly more effective for younger aged patients (P = 0.011). CONCLUSIONS: Factors such as older age, acute arch angle, higher elongation type, arch calcification, and carotid artery angulation were verified as factors affecting access by a simple catheter; however, neck extension was shown to facilitate access in about 10%-30% of patents.

The fabrication of functional biosurface composed of iron storage protein, ferritin.

A functional biosurface applicable to a biomemory device was fabricated using ferritin, which is one of the globular protein complexes consisting of 24 protein subunits, which can be classified as metalloproteins. For the fabrication of uniform ferritin layer, 11-MUA(11-mercaptoundecanoic acid) was used as a linker material. The formation of the ferritin layer was confirmed by surface plasmon resonance (SPR) spectroscopy, and the morphology of the immobilized ferritin was analyzed by scanning tunneling microscopy (STM). The electrochemical redox property investigation was accomplished by the cyclic voltammetry (CV) technique. These results of adsorbed ferritin on the modified electrode can be used for the fabrication of bioelectronics.

Direct immobilization of cupredoxin azurin modified by site-directed mutagenesis on gold surface.

For making efficient bioelectronic device, we have developed novel immobilization method of cupredoxin azurin modified on gold (Au) surface. A recombinant protein with cysteine residue by using site-directed mutagenesis was designed and then directly immobilized on Au surface without any chemical linker. The immobilization of the functionalized protein is confirmed by surface plasmon resonance (SPR) and its surface morphology is analyzed by scanning tunneling microscopy (STM). The immobilization efficiency has been increased about 75.6%, as compared to that of wild-type azurin. The electrochemical property of the fabricated thin film was investigated by the cyclic voltammetry (CV). As a result, cysteine-modified azurin can be used for making high-quality protein film, and applied to the fabrication of nano-scale bioelectronics.