Rational Design of a Bifunctional Peptide Exhibiting Lithium Titanate Oxide and Carbon Nanotube Affinities for Lithium-Ion Battery Applications.

Phage display is employed as a method for identifying polypeptides that bind to lithium-ion battery materials, specifically lithium titanate oxide (LTO) and multiwalled carbon nanotubes (MWCNTs). Output/input assays are used as a quantitative measure to narrow down the strongest binding polypeptides from several peptides selected through biopanning. Negatively stained transmission electron microscopy is used to verify that a phage presenting a particular LTO or MWCNT binding peptide sequence colocalizes with the respective material. Heterologous expression allows for ample polypeptides to be grown and purified using a peptide expression vector. Isothermal titration calorimetry in conjunction with alanine scanning enables determination of the pertinent residues involved in LTO binding and yields a dissociation constant of 3.41 µM. A rationally designed bifunctional peptide exhibiting LTO and MWCNT binding domains is subsequently validated to exhibit both LTO and MWCNT affinities and is incorporated as a binding agent in LTO coin-type electrochemical cells where the bifunctional peptide demonstrates stability at high cycle rates and potential as an alternative to non-specific binding agents for aqueous slurry processing of lithium-ion battery electrodes.

Prophylactic Bronchial Stump Support With Intrathoracic Muscle Flap Transposition.

BACKGROUND: Bronchopleural fistula (BPF) is a dreaded complication of pulmonary resection. For high-risk patients, bronchial stump coverage with vascularized tissue has been recommended. The goal of this study was to report our experience with intrathoracic muscle transposition for bronchial stump coverage. METHODS: A retrospective review of all patients who underwent intrathoracic muscle flap transposition as a prophylactic measure at our institution between 1990 and 2010 was conducted. Demographics, surgical characteristics, and complication rates were abstracted and analyzed. RESULTS: A total of 160 patients were identified. The most common lung resections performed were pneumonectomy (n = 69, 43%) and lobectomy (n = 60, 38%). A total of 168 flaps were used where serratus anterior was the most common flap (n = 136, 81%), followed by intercostal (n = 14, 8%), and latissimus dorsi (n = 12, 7%). Ten patients (6%) developed BPF, and empyema occurred in 13 patients (8%). Median survival was 20 months, and operative mortality occurred in 7 patients (4%). CONCLUSIONS: Reinforcement of the bronchial closure with vascularized muscle is a viable option for potentially decreasing the incidence of BPF in high-risk patients. Further randomized studies are needed to determine the efficacy of this technique for BPF prevention.

Intrathoracic Muscle Flap Transposition for the Management of Chronic Pulmonary Aspergillosis.

BACKGROUND: The management of chronic pulmonary aspergillosis remains a challenge for thoracic and reconstructive surgeons. Different management options have been proposed with no consensus regarding the best treatment modality. The goal of this study is to report our experience with the use of intrathoracic muscle flaps for the management of pulmonary aspergillosis. METHODS: We retrospectively reviewed all patients who underwent intrathoracic muscle flap transposition for the management of pulmonary aspergillosis between 1990 and 2010. Demographics, surgical characteristics, and treatment outcomes were collected and analyzed. RESULTS: A total of 39 patients who underwent 48 muscle flaps were identified. The majority were classified as ASA 3 (n=30, 77%) or ASA 4 (n=8, 21%). Serratus anterior was the most common flap used (n=34), followed by latissimus dorsi (n=6) and pectoralis major (n=5). Flap loss was encountered in three (8%) patients (2 partial, 1 total). Bronchopleural fistula and empyema comprised the two most common intrathoracic complications (26%, 29% respectively). Median follow-up was 33 months (range, 0-216). Successful treatment was achieved in 77% of patients, while operative mortality was 23%. CONCLUSION: The use of intrathoracic muscle flaps can be a helpful adjunct to surgical resection in the treatment of chronic pulmonary aspergillosis with low rates of flap loss.

Muscle Flap Transposition for the Management of Intrathoracic Fistulas.

BACKGROUND: Intrathoracic fistulas pose unique challenges for thoracic and reconstructive surgeons. To decrease the incidence of fistula recurrence, pedicled flaps have been suggested to buttress the repair site. The authors aimed to report their experience with muscle flap transposition for the management of intrathoracic fistulas. METHODS: A retrospective review of all patients who underwent intrathoracic muscle flap transposition for the management of intrathoracic fistulas from 1990 to 2010 was conducted. Patient demographics, surgical characteristics, and complication rates were abstracted and analyzed. RESULTS: A total of 198 patients were identified. Bronchopleural fistula was present in 156 of the patients (79 percent), and 48 had esophageal fistula (24 percent). A total of 238 flaps were used, constituting an average of 1.2 flaps per patient. After the initial fistula repair, bronchopleural fistula complicated the course of 34 patients (17 percent), and esophageal fistula occurred in 13 patients (7 percent). Partial flap loss was identified in 11 flaps (6 percent), and total flap loss occurred in four flaps (2 percent). Median follow-up was 27 months. At the last follow-up, 182 of the patients (92 percent) had no evidence of fistula, 175 (89 percent) achieved successful chest closure, and 164 (83 percent) had successful treatment. Preoperative radiation therapy and American Society of Anesthesiologists score of 4 or greater were identified as risk factors for unsuccessful treatment. CONCLUSIONS: Intrathoracic fistulas remain a source of major morbidity and mortality. Reinforcement of the fistula closure with vascularized muscle flaps is a viable option for preventing dehiscence of the repair site and can be potentially life-saving. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Bioprospecting solid binding polypeptides for lithium ion battery cathode materials.

Biotemplating presents a promising approach to improve the performance of inorganic materials via specific control over morphology, crystal structure, and the size of particles during synthesis and assembly. Among other biotemplates, solid binding polypeptides (SBPs) isolated for the material of interest provide high binding affinity and selectivity due to distinct combinations of functional groups found in amino acids. Nanomaterials assembled and synthesized with SBPs have found widespread applications from drug delivery to catalysis and energy storage due to their improved properties. In this study, the authors describe the identification of SBPs for binding to Li-ion battery cathode materials LiCoPO4, LiMn1.5Ni0.5O4, and LiMn2O4, which all have potential for improvement toward their theoretical values. The binding affinity of isolated peptides was assessed via phage binding assays and confirmed with electron microscopy in order to select for potential biotemplates. The authors demonstrate ten binding peptides for each material and analyze the sequences for enrichment in specific amino acids toward each structure (olivine and spinel oxide), as well as the test for specificity of selected sequences. In further studies, the authors believe that the isolated SBPs will serve as a template for synthesis and aid in assembly of cathode materials resulting in improved electrochemical properties for Li-ion batteries.

A versatile expression vector for the growth and amplification of unmodified phage display polypeptides.

Proteins and polypeptides represent nature's most complex and versatile polymer. They provide complicated shapes, diverse chemical functionalities, and tightly regulated and controlled sizes. Several disease states are related to the misfolding or overproduction of polypeptides and yet polypeptides are present in several therapeutic molecules. In addition to biological roles; short chain polypeptides have been shown to interact with and drive the bio-inspired synthesis or modification of inorganic materials. This paper outlines the development of a versatile cloning vector which allows for the expression of a short polypeptide by controlling the incorporation of a desired DNA coding insert. As a demonstration of the efficacy of the expression system, a solid binding polypeptide identified from M13 phage display was expressed and purified. The solid binding polypeptide was expressed as a soluble 6xHis-SUMO tagged construct. Expression was performed in E. coli using auto-induction followed by Ni-NTA affinity chromatography and ULP1 protease cleavage. Methodology demonstrates the production of greater than 8 mg of purified polypeptide per liter of E. coli culture. Isotopic labeling of the peptide is also demonstrated. The versatility of the designed cloning vector, use of the 6xHis-SUMO solubility partner, bacterial expression in auto-inducing media and the purification methodology make this expressionun vector a readily scalable and user-friendly system for the creation of desired peptide domains.

Temperature dependence of electron magnetic resonance spectra of iron oxide nanoparticles mineralized in Listeria innocua protein cages.

Electron magnetic resonance (EMR) spectroscopy was used to determine the magnetic properties of maghemite (γ-Fe(2)O(3)) nanoparticles formed within size-constraining Listeria innocua (LDps)-(DNA-binding protein from starved cells) protein cages that have an inner diameter of 5 nm. Variable-temperature X-band EMR spectra exhibited broad asymmetric resonances with a superimposed narrow peak at a gyromagnetic factor of g ≈ 2. The resonance structure, which depends on both superparamagnetic fluctuations and inhomogeneous broadening, changes dramatically as a function of temperature, and the overall linewidth becomes narrower with increasing temperature. Here, we compare two different models to simulate temperature-dependent lineshape trends. The temperature dependence for both models is derived from a Langevin behavior of the linewidth resulting from "anisotropy melting." The first uses either a truncated log-normal distribution of particle sizes or a bi-modal distribution and then a Landau-Liftshitz lineshape to describe the nanoparticle resonances. The essential feature of this model is that small particles have narrow linewidths and account for the g ≈ 2 feature with a constant resonance field, whereas larger particles have broad linewidths and undergo a shift in resonance field. The second model assumes uniform particles with a diameter around 4 nm and a random distribution of uniaxial anisotropy axes. This model uses a more precise calculation of the linewidth due to superparamagnetic fluctuations and a random distribution of anisotropies. Sharp features in the spectrum near g ≈ 2 are qualitatively predicted at high temperatures. Both models can account for many features of the observed spectra, although each has deficiencies. The first model leads to a nonphysical increase in magnetic moment as the temperature is increased if a log normal distribution of particles sizes is used. Introducing a bi-modal distribution of particle sizes resolves the unphysical increase in moment with temperature. The second model predicts low-temperature spectra that differ significantly from the observed spectra. The anisotropy energy density K(1), determined by fitting the temperature-dependent linewidths, was ∼50 kJ/m(3), which is considerably larger than that of bulk maghemite. The work presented here indicates that the magnetic properties of these size-constrained nanoparticles and more generally metal oxide nanoparticles with diameters d < 5 nm are complex and that currently existing models are not sufficient for determining their magnetic resonance signatures.

M13 bacteriophage display framework that allows sortase-mediated modification of surface-accessible phage proteins.

We exploit bacterial sortases to attach a variety of moieties to the capsid proteins of M13 bacteriophage. We show that pIII, pIX, and pVIII can be functionalized with entities ranging from small molecules (e.g., fluorophores, biotin) to correctly folded proteins (e.g., GFP, antibodies, streptavidin) in a site-specific manner, and with yields that surpass those of any reported using phage display technology. A case in point is modification of pVIII. While a phage vector limits the size of the insert into pVIII to a few amino acids, a phagemid system limits the number of copies actually displayed at the surface of M13. Using sortase-based reactions, a 100-fold increase in the efficiency of display of GFP onto pVIII is achieved. Taking advantage of orthogonal sortases, we can simultaneously target two distinct capsid proteins in the same phage particle and maintain excellent specificity of labeling. As demonstrated in this work, this is a simple and effective method for creating a variety of structures, thus expanding the use of M13 for materials science applications and as a biological tool.

Analyses of soft tissue from Tyrannosaurus rex suggest the presence of protein.

We performed multiple analyses of Tyrannosaurus rex (specimen MOR 1125) fibrous cortical and medullary tissues remaining after demineralization. The results indicate that collagen I, the main organic component of bone, has been preserved in low concentrations in these tissues. The findings were independently confirmed by mass spectrometry. We propose a possible chemical pathway that may contribute to this preservation. The presence of endogenous protein in dinosaur bone may validate hypotheses about evolutionary relationships, rates, and patterns of molecular change and degradation, as well as the chemical stability of molecules over time.