CNT Binding Peptides Selected by the Phage Display Method.

Using the M13 phage display method, 236 amino acid sequences (peptide aptamers) that could specifically adsorb to CNTs were selected. These peptide aptamers had abundant hydrophobic amino acids and evenly dispersed charged amino acids. The hydrophobic amino acids were postulated to contribute to CNT adsorption, while the charged amino acids contribute to their aqueous solubility. The frequency of proline amino acids, which causes the amino acid main chain bending, was slightly higher than in nature, suggesting that some conformational constraint might be required. Four peptide aptamers with a high frequency of occurrence in the selected sequences were further studied. Hydrophobicity scores were periodic along the amino acid sequence. 3D structure predictions by PEP-FOLD3 indicated that these aptamers would take a helical structure with hydrophobic amino acid residues on one side, suggesting that the aptamers bind hydrophobically to the CNT. The adsorption of these four aptamers to the carbon electrode was confirmed by electrochemical impedance spectroscopy, which demonstrated the effectiveness of the phage display method. At the same time, it was shown that even for selected peptides, the adsorption performance varied, and verification was needed.

Influence of halogen elements in organic salts on n-type doping of CNT yarn for thermoelectric applications.

Doping control of carbon nanotube (CNT) is crucial for thermoelectric (TE) application to maximize the power conversion efficiency. Despite the recent achievement of good air stability by organic salts for n-type carrier doping, their doping mechanism has not been systematically investigated so far. Here, we demonstrate doping of CNT yarn using ammonium salts with different halogen elements (tetra-butylammonium salts, TBAX where X = Cl, Br, or I) through the dipping technique. By changing the halogen element, we specifically investigated the halogen effect in the n-type doping process of CNT. The introduction of each material into the CNT yarn and its doping reaction were then studied by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Halogen element was found to affect the excess amount of TBA+ cation in the CNT yarn. The largest amount of excess TBA+ is found in the TBAI-doped yarn, which stabilizes the most amount of negative charge in CNT, enhancing the TE performance and its stability over one month in air. This study discovers the importance of the halogen element in the doping process of CNT-based TE materials by organic salts, simultaneously offering an efficient and stable n-type doping strategy.

Treatment strategies for recurrent dislocation following total hip arthroplasty: relationship between cause of dislocation and type of revision surgery.

BACKGROUND: There are many therapeutic options for dislocation following total hip arthroplasty (THA). The aim of this study was to evaluate the results of revision surgery for dislocated hips. METHODS: Between November 2001 and December 2020, 71 consecutive revision hip surgeries were performed at our institution for recurrent dislocation following THA. We conducted a retrospective study of all 65 patients (71 hips), who were followed for a mean of 4.7 ± 3.2 years (range, 1-14). The cohort included 48 women and 17 men, with a mean age of 71 ± 12.3 years (range, 34-92). The mean number of previous surgeries was 1.6 ± 1.1 (range, 1-5). From intraoperative findings, we created six categories of revision hip surgery for recurrent dislocation following THA: open reduction and internal fixation (2 hips); head change or liner change only (6 hips); cup change with increased head size only (14 hips); stem change only (7 hips); cup and stem change (24 hips); and conversion to constrained cup (18 hips). Prosthesis survival was analyzed by the Kaplan-Meier method, with repeat revision surgery for re-dislocation or implant failure as the endpoint. A cox proportional hazards model was used for risk factors of re-revision surgery. RESULTS: Re-dislocation occurred in 5 hips (7.0%) and implant failure in 1 hip (1.4%). The 10-year survival rate was 81.1% (95% confidence interval, 65.5-96.8). A Dorr classification of "positional" was a risk factor for re-revision surgery due to re-dislocation. CONCLUSION: Clear understanding of the cause of dislocation is essential for optimizing revision procedures and improving the rate of successful outcomes.

The Role of Structural Order in the Mechanism of Charge Transport across Tunnel Junctions with Various Iron-Storing Proteins.

In biomolecular electronics, the role of structural order in charge transport (CT) is poorly understood. It has been reported that the metal oxide cores of protein cages (e.g., iron oxide and ferrihydrite nanoparticles (NPs) present in ferritin and E2-LFtn, which is E2 protein engineered with an iron-binding sequence) play an important role in the mechanism of CT. At the same time, the NP core also plays a major role in the structural integrity of the proteins. This paper describes the role of structural order in CT across tunnel junctions by comparing three iron-storing proteins. They are (1) DNA binding protein from starved cells (Dps, diameter (∅) = 9 nm); (2) engineered archaeal ferritin (AfFtn-AA, ∅ = 12 nm); and (3) engineered E2 of pyruvate dehydrogenase enzyme complex (E2-LFtn, ∅ = 25 nm). Both holo-Dps and apo-Dps proteins undergo CT by coherent tunneling because their globular architecture and relative structural stability provide a coherent conduction pathway. In contrast, apo-AfFtn-AA forms a disordered structure across which charges have to tunnel incoherently, but holo-AfFtn-AA retains its globular structure and supports coherent tunneling. The large E2-LFtn always forms disordered structures across which charges incoherently tunnel regardless of the presence of the NP core. These findings highlight the importance of structural order in the mechanism of CT across biomolecular tunnel junctions.

Endofemoral Shooting Technique for Removing Well-fixed Cementless Stems.

Background: The removal of a well-fixed cementless stem poses technical challenges. The aim of this study was to evaluate the outcomes of our endofemoral extraction technique established in 2001. Methods: Between January 2001 and December 2016, 118 consecutive revisions following bipolar or total hip arthroplasty, which required cementless femoral stem removal, were performed at our institution. This retrospective study evaluated 106 patients (108 hips) who were followed up for a mean of 9.2 years (range, 5-20 years). The patients included 15 men and 91 women with a mean age of 65 years (range, 33-87 years). Endofemoral extracted stem removal was performed as follows. Multiple Kirschner wires were sequentially inserted into the interface between the implant and cortical bone, after which the implant was detached using a thin chisel. After the cementless stem was removed, it was replaced with a cemented stem using an autograft, as needed. Radiological loosening of the femoral stem was defined as definite or probable loosening, based on the criteria of Harris et al. Prosthesis survival was analyzed using the Kaplan-Meier method, with the endpoint set as repeat revision surgery for stem loosening or femoral fracture. Results: Re-revision surgery was performed in 7 hips. Stem loosening was observed in 4 hips, and the mean subsidence was 0.3 mm (0-3 mm). The 10-year survival rate was 97.7% (95% confidence interval, 93.2-100). Conclusions: Our technique for removing well-fixed cementless stems yielded successful results.

One-step construction of ferritin encapsulation drugs for cancer chemotherapy.

Conventionally, a disassembly and reassembly method has been used for encapsulation of drug molecules in ferritin protein nano-cages. However, clinical applications of ferritin have been greatly restricted by its limited drug-loading capacity and process complexity. Here, we establish a simple high yield process for preparing high drug-loaded ferritin nanomedicine for industrial production. A complex of ferritin and a target drug was obtained by incubating the mixture at an appropriate pH. An electrostatic charge potential and small ferritin cavity facilitates the passage of drug molecules through the pores, traversing the ferritin shell and enabling deposition of the drug in the ferritin cavity. Compared to the disassembly/reassembly method, the loading capacity of a doxorubicin-loaded ferritin heavy chain (DOX-FTH), constructed by our novel method, was over 3-fold higher, while doxorubicin recovery was 10-fold higher. Results of transmission electron microscopy, size exclusion chromatography, dynamic light scattering, and zeta potential indicate that DOX-FTH exhibits the same physicochemical characteristics of natural apo-ferritin. Moreover, DOX-FTH can be taken up and induce apoptosis of cancer cells overexpressing TfR1. Here, we have demonstrated the successful introduction of more than ten drug molecule types into ferritin nano-cages using a novel method. These results demonstrate that this one-step method is a powerful production process to construct a drug-loading ferritin drug delivery system carrier.

Reattachment of an osteotomized greater trochanter in total hip arthroplasty using an ultra-high molecular weight polyethylene fiber cable.

BACKGROUND: The optimum approach in total hip arthroplasty (THA) should reduce the risk of postoperative dislocation or limping, be applicable in every case, and be reusable in the future. The purpose of this study was to introduce our transgluteal approach for THA and to evaluate the type and frequency of complications around the greater trochanter. METHODS: This study retrospectively evaluated 892 THA cases between January 2010 and March 2015 performed using our transgluteal approach that osteotomized only the lateral anteroinferior greater trochanter. The trochanteric fragment was reattached using one of three different protocols: Group A, three non-absorbable polyester sutures; Group B, two non-absorbable polyester sutures and one ultra-high molecular weight polyethylene (UHMWPE) fiber cable; or Group C, two UHMWPE fiber cables. Postoperative complications were assessed and recorded, and univariate logistic regression analyses were performed to determine whether risk factors and radiological complications around the greater trochanter were correlated. RESULTS: None of the hips required revision for infection, dislocation, or limping. The rate of radiological complications around the greater trochanter at 1 year was 19.2% in Group A, 16.3% in Group B, and 7.9% in Group C (p < 0.001). Risk factors for radiological complications included the patient's disease or the surgeon's experience in Group A and the patient's age or the surgeon's experience in Group C. In the relationship between postoperative pain around the greater trochanter and radiological complications, there were no significant differences in all groups; no group interaction was observed (p= 0.3875). CONCLUSION: The UHMWPE fiber cable was effective to reduce complications of the reattached osteotomized greater trochanter in THA.

Easy and green preparation of a graphene-TiO2 nanohybrid using a supramolecular biomaterial consisting of artificially bifunctionalized proteins and its application for a perovskite solar cell.

We report a novel preparation method for a graphene/TiO2 nanohybrid using a supramolecular biomaterial (CDT1). CDT1 can offer an increase in the dispersibility of graphene in water and subsequent complexation of graphene and TiO2. This nanohybrid was applied to a perovskite solar cell and success was achieved in improving its photoelectric conversion efficiency.

In vivo serum concentration of vancomycin in antibiotic-loaded acrylic cement for the treatment and prevention of periprosthetic hip infection.

BACKGROUND: Although antibiotic-loaded acrylic cement (ALAC) is used to prevent and treat periprosthetic hip infection, it is unknown how much antibiotic is deposited in the body in vivo, how high the serum concentration rises, or how long its effects last. The aim of this study was firstly to determine the amount of vancomycin (VCM) deposited as ALAC in the body, and secondly to assess the safety and drug elution profile of VCM in ALAC. METHODS: We administered VCM to prevent infection after total hip arthroplasty (THA) or to treat patients with methicillin-resistant Staphylococcus aureus. Patients were classified into two groups: a low-dose group (21 hips) that received primary THA for high-risk cases, revision THA without infection, or one-staged revision THA for infection; and a high-dose group (6 hips) that received cement beads during a two-staged revision THA. The amount of VCM placed as ALAC into the hip was calculated using the remaining ALAC. The serum concentrations of VCM and creatinine were evaluated at postoperative days 1, 4, 7, 14, and 28, and at 3 and 6 months. RESULTS: The mean amount of VCM placed as ALAC into the hip was 0.9 g and 3.4 g for cemented THA and cement beads, respectively (P < 0.0001). The mean serum concentration of VCM from ALAC in the high-dose group was significantly increased compared with that in the low-dose group on postoperative days 1, 4, 7, 14, and 28 (P < 0.0001), but it remained within a clinically safe range. No significant differences were observed between the preoperative and postoperative serum creatinine levels of either group. CONCLUSION: The average serum concentrations of VCM from ALAC were always less than the effective blood concentration, and were detectable until 6 months after surgery.

Dispersed Gold Nanoparticle Array Produced by Apoferritins Utilizing Biomineralization and Chemical Conversion.

A new method for producing a dispersed gold nanoparticle (Au NP) array to anchor probe DNAs onto a DNA-sensing electrode has been developed. A homogenous gold sulfide (Au2S) core (precursor of Au NP) was biomineralized in the cavity of a mutant apoferritin (K98E) with enhanced negative outer-surface charges. We employed a slow chemical reaction system utilizing a stable cationic gold complex. K98E could attract the gold complex, and Au2S NPs were synthesized. K98E enabled dispersed placement of the synthesized Au2S core onto a cationic 3-aminopropyltriethoxysilane (APTES) layer on a substrate. UV-ozone treatment eliminated the protein shells and APTES layer. X-ray photoelectron spectroscopy confirmed that the Au2S core was reduced to Au NPs under the same treatment. Atomic force microscopy (AFM) clearly showed that the combination of apoferritin versatility, chemical system design, and UV-ozone treatment successfully produced a dispersed Au NP array on the substrate.

Bone Remodeling in Acetabular Reconstruction Using a Kerboull-Type Reinforcement Device and Structural Bone-Grafting in Total Hip Arthroplasty.

BACKGROUND: The purpose of this study was to identify the long-term durability of the Kerboull-type reinforcement device (KT plate) in acetabular reconstruction for massive bone defects, assessing the remodeling of structural bone grafts. METHODS: This study retrospectively evaluated 106 hips that underwent acetabular reconstruction using a KT plate between November 2000 and December 2010. Thirty-eight primary total hip arthoplasties (THAs) and 68 revised THAs were performed, and the mean duration of clinical follow-up was 8 years (5-14 years). Regarding reconstructing the acetabular bone defects, autografts were used in 37 hips, allografts in 68 hips, and A-W glass ceramics in 2 hips. RESULTS: One hip exhibited radiological migration and no revision for aseptic loosening. The mean Merle d'Aubigné Clinical Score improved from 7.5 points (4-12 points) preoperatively to 10.9 points (9-18 points) at the last follow-up. The Kaplan-Meier survival rate for radiological migration of primary and revised THAs at 10 years was 100% and 97% (95% confidence interval: 96%-100%), respectively. Bone remodeling was evaluated using the radiological demarcation at the bone-to-bone interface, and an improvement of 100% in primary THAs and 94% in revised THAs was observed. CONCLUSION: For massive bone defects, acetabular reconstruction using the KT plate with a structural bone grafting can yield successful results.

Creating Reversible p-n Junction on Graphene through Ferritin Adsorption.

An alternative way to construct a stable p-n junction on graphene-based field effect transistor (G-FET) through physical adsorption of ferritin (spherical protein shell) is presented. The produced p-n junction on G-FET could also operate through water-gate. Native ferritins are known to be negatively charged in wet condition; however, we found that native negatively charged ferritins became positively charged after performing electron beam (EB)-irradiation. We utilized this property to construct p-n junction on G-FET. We found also that EB-irradiation could remove the effect of charged impurity adsorbed on graphene layer, thus the Dirac point was adjusted to gate voltage Vg = 0.

Long-term results of acetabular reconstruction using three bulk bone graft techniques in cemented total hip arthroplasty for developmental dysplasia.

PURPOSE: The aims of this retrospective study were to firstly introduce three practical bulk bone graft techniques based on acetabular morphology for dysplasia and secondly evaluate the long-term durability of acetabular reconstruction using those techniques combined with cemented total hip arthroplasty (THA). METHODS: The study comprised 101 consecutive THAs with a minimum follow-up of ten years; these procedures were categorised as being L shape (n = 58), Wall (n = 33) and D shape (n = 10) types. RESULTS: At the last follow-up, all bone grafts acquired trabecular reorientation, and no evidence of revision for aseptic or radiological loosening was noted. CONCLUSIONS: These bone graft techniques will be effective for improving the management of dysplasia in cemented THA by providing both acetabular reconstruction and cement containment.

Thermo-stable carbon nanotube-TiO2 nanocompsite as electron highways in dye-sensitized solar cell produced by bio-nano-process.

We produced a thermostable TiO2-(anatase)-coated multi-walled-carbon-nanotube (MWNT) nanocomposite for use in dye-sensitized solar cells (DSSCs) using biological supuramolecules as catalysts. We synthesized two different sizes of iron oxide nanoparticles (NPs) and arrayed the NPs on a silicon substrate utilizing two kinds of genetically modified cage-shaped proteins with silicon-binding peptide aptamers on their outer surfaces. Chemical vapor deposition (CVD) with the vapor-liquid-solid phase (VLS) method was applied to the substrate, and thermostable MWNTs with a diameter of 6 ± 1 nm were produced. Using a genetically modified cage-shaped protein with carbon-nanomaterials binding and Ti-mineralizing peptides as a catalyst, we were able to mineralize a titanium compound around the surface of the MWNT. The products were sintered, and thin TiO2-layer-coated MWNTs nanocomoposites were successfully produced. Addition of a 0.2 wt% TiO2-coated MWNT nanocomposite to a DSSC photoelectrode improved current density by 11% and decreased electric resistance by 20% compared to MWNT-free reference DSSCs. These results indicate that a nanoscale TiO2-layer-coated thermostable MWNT structure produced by our mutant proteins works as a superior electron transfer highway within TiO2 photoelectrodes.

Floating gate memory with charge storage dots array formed by Dps protein modified with site-specific binding peptides.

We report a nanodot (ND) floating gate memory (NFGM) with a high-density ND array formed by a biological nano process. We utilized two kinds of cage-shaped proteins displaying SiO2 binding peptide (minTBP-1) on their outer surfaces: ferritin and Dps, which accommodate cobalt oxide NDs in their cavities. The diameters of the cobalt NDs were regulated by the cavity sizes of the proteins. Because minTBP-1 is strongly adsorbed on the SiO2 surface, high-density cobalt oxide ND arrays were obtained by a simple spin coating process. The densities of cobalt oxide ND arrays based on ferritin and Dps were 6.8 × 10(11) dots cm(-2) and 1.2 × 10(12) dots cm(-2), respectively. After selective protein elimination and embedding in a metal-oxide-semiconductor (MOS) capacitor, the charge capacities of both ND arrays were evaluated by measuring their C-V characteristics. The MOS capacitor embedded with the Dps ND array showed a wider memory window than the device embedded with the ferritin ND array. Finally, we fabricated an NFGM with a high-density ND array based on Dps, and confirmed its competent writing/erasing characteristics and long retention time.

Pre-operative scoring system to determine the surgical strategy for periprosthetic hip infection.

PURPOSE: The aim of this study was to evaluate the results of one- and two-stage revision total hip arthroplasties (THAs) and to determine a rational surgical treatment strategy for periprosthetic hip infections. METHODS: We constructed a 12-point preoperative scoring system to suggest either one- or two-stage revision THAs, based on a retrospective analysis of 55 operative procedures. Prosthesis survival was analysed using the Kaplan-Meier method, and the validity of the scoring system was evaluated using receiver-operating characteristic curves. RESULTS: At the end point of implant removal due to recurrent infection, the ten year survival rates were 94 and 87% for one- and two-stage revision THAs, respectively. One-stage revision THA was recommended for patients scoring >9 points. The risk of recurrent infection in patients scoring 4 points was 83%. The sensitivity and specificity of a cut-off value of 4 points, determined by the scoring system, were 83 and 100%, respectively. CONCLUSIONS: The novel pre-operative scoring system was useful for the management of periprosthetic hip infections.

Induction of autoimmune arthritis after direct injection of bone marrow cells from arthritis-prone SKG/Jcl mice into bone cavity of normal mice.

SKG/Jcl (SKG) mice spontaneously develop T cell-mediated autoimmune arthritis and may be an effective model for studying human rheumatoid arthritis. We sought to confirm that arthritis in SKG mice was caused by stem cell disorders. We induced systemic arthritis in normal C57/BL6 (B6) mice (H-2(b) type) by injecting lineage-negative (lin(-)) immature cells isolated from bone marrow cells (BMCs) of SKG mice (H-2(d) type) directly into bone cavities. Twenty weeks later, we analyzed arthritis scores, hematoxylin-eosin (H-E) staining and tartrate-resistant acid phosphatase (TRAP) staining in ankle joints, H-2 type of hematolymphoid and osteoblast-like cells, serum levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) and percentages of CD4(+) T cells and osteoblast-like cells expressing receptor activator of nuclear factor kappa-B ligand (RANKL) in recipient mice. Donor-derived hematolymphoid cells and osteoblast-like cells had completely replaced donor-derived cells in the recipients (H-2(b) to H-2(d)). All recipients showed severe joint swelling with hyperemia and developed hypertrophic synovitis with lymphocytes accumulated around joints. All recipients also had higher TNF-α and IL-6 levels than untreated B6 controls. Furthermore, the percentages of CD4(+) T cells and osteoblast-like cells expressing RANKL and the number of TRAP(+) cells were greater in treated animals. Donor-derived hematolymphoid cells and osteoblast-like cells persisted in these recipients and promoted autoimmune arthritis and an increase in osteoclasts. Because autoimmune arthritis may be associated with abnormal lin(-) immature cells, patients with intractable autoimmune arthritis may be treated by replacing these cells with direct injection of lin(-) immature cells isolated from normal BMCs.

Controlled charged amino acids of Ti-binding peptide for surfactant-free selective adsorption.

The adsorption mechanism of titanium-binding peptide (TBP) on metal oxide substrates was investigated by evaluating the adsorption behavior of ferritins with various alanine-substituted TBPs. Results revealed that (a) a positively charged amino acid, lysine (K) or arginine (R), in TBP can anchor ferritin to negative zeta-potential substrates, (b) the adsorption force of K is stronger than R, and (c) local electrostatic interactions and flexibility of TBP directly affect adsorption. Based on these findings, selective ferritin adsorption on SiO2 with TiOX patterned surfaces in a surfactant-free condition was demonstrated. Alanine-substituted TBP with one positively charged amino acid (K) and one negatively charged amino acid (D), achieved ferritin-selective adsorption without a surfactant. The importance of controlled electrostatic forces between TBP and a substrate for selective adsorption without a surfactant was clearly demonstrated.

Subtrochanteric shortening osteotomy combined with cemented total hip arthroplasty for Crowe group IV hips.

BACKGROUND: Total hip arthroplasty (THA) is a challenging surgical procedure that can be used to treat severely dislocated hips. There are few reports regarding cemented THAs involving subtrochanteric shortening osteotomy (SSO), even though cemented THAs provide great advantages because the femur is generally hypoplastic with a narrow, deformed canal. PURPOSES: We evaluated the utility of cemented THA with SSO for Crowe group IV hips, and assessed the relationship between leg lengthening and nerve injury. Our goal was to describe surgical techniques for optimizing surgical outcomes while minimizing the risk of nerve injury. METHODS: We retrospectively reviewed 34 cases of cemented THAs with transverse SSO for Crowe group IV. Prior to surgery, mean hip flexion was 93.1° (40°-130°). The mean follow-up period was 5.2 years (3-10 years). RESULTS: Bone union took an average of 7.7 months (3-24 months). Mean leg lengthening was 40.5 mm (15-70 mm) and was greater in patients without hip flexion contracture. None of the patients experienced any nerve injuries associated with leg lengthening, and radiographic evidence of loosening was not observed at the final follow-up. CONCLUSIONS: SSO combined with cemented THA is an effective treatment for severely dislocated hips. Leg lengthening is not necessarily associated with nerve injuries, and the likelihood of this surgical complication may be related to the presence of hip flexion contracture.