Melanin: Nature's 4th bioorganic polymer.

The pigments known as the melanins are widely recognized for their responsibility in the coloration of human skin, eyes, hair, and minimising the harmful effects of solar ultraviolet radiation. But specialists are aware that the melanins are present in all living kingdoms, barring viruses, and have functionality that extends beyond neutralizing ionising radiation. The ubiquitous presence of melanin in almost all human organs, recognized in recent years, as well as the presence of melanin in organisms that are evolutionarily distant from each other, indicate the fundamental importance of this class of material for all life forms.

Validity and reliability of the adapted Dutch version of the Brace Questionnaire (BrQ).

Background And Purpose: The Brace Questionnaire (BrQ) is a disease-specific health-related quality of life (HRQOL) instrument for measuring perceived health status of scoliosis patients undergoing brace treatment. The purpose of this study is to evaluate the validity and reliability of a translated and culturally adapted Dutch version of the BrQ.

Patients And Methods: The original Greek BrQ was translated into Dutch and a cross-cultural adaptation and validation processes were conducted.

Signatures of pancake bonding in hydrated eumelanin.

Pancake bonding phenomenology is applied for the first time in a bioorganic system, the pigment eumelanin, a hydration-induced decrease of the interplanar distance down to 3.19 Å. The observation explains the long-term inconsistency between electron paramagnetic resonance and muon spin relaxation data for eumelanin.

The influence of copper ions on the transport and relaxation properties of hydrated eumelanin.

Eumelanin, the human skin pigment, is a poly-indolequinone material possessing a unique combination of physical and chemical properties. For numerous applications, the conductivity of eumelanin is of paramount importance. However, its hydration dependent conductivity is not well studied using transport-relaxation methods.

The risk of delayed spinal cord injury in pediatric spinal deformity surgery.

Delayed spinal cord injury (SCI) hours or days after surgery, with uneventful monitoring and initial normal postoperative neurological examination, is a rare complication. Based on anecdotal evidence, the risk of delayed spinal cord injury might be higher than previously assumed. Therefore the aim of this study was to determine the risk of delayed SCI after pediatric spinal deformity surgery between 2013-2019 in the Netherlands.

Systematic hydration neutron reflectometry study on Nafion thin films.

Reported herein is a neutron reflectometry (NR) study on hydrated Nafion thin films (∼30 nm) on a silicon substrate with native oxide. The Nafion morphology is investigated systematically across the whole relative humidity range using both HO and DO vapours to enable a comparative study. By utilising this systematic approach two key results have been obtained.

The importance of water content on the conductivity of biomaterials and bioelectronic devices.

Conductive biocompatible-, bioinspired- and biomaterials are increasing in importance, especially in bioelectronic applications where these materials are used in a variety of devices. Given the intended purpose of many of these devices is to interface with the human body, a pertinent issue is the effect of water from the environment on the electrical properties of the materials and devices. A researcher on biomaterials may currently not be aware, but the conductivity of these materials and device performances can be significantly altered with the presence of hydration in the environment.

Water-Activated Semiquinone Formation and Carboxylic Acid Dissociation in Melanin Revealed by Infrared Spectroscopy.

Eumelanin is a widespread biomacromolecule pigment in the biosphere and has been widely investigated for numerous bioelectronics and energetic applications. Many of these applications depend on eumelanin's ability to conduct proton current at various levels of hydration. The origin of this behavior is connected to a comproportionation reaction between oxidized and reduced monomer moieties and water.

Integrated bioelectronic proton-gated logic elements utilizing nanoscale patterned Nafion.

A central endeavour in bioelectronics is the development of logic elements to transduce and process ionic to electronic signals. Motivated by this challenge, we report fully monolithic, nanoscale logic elements featuring n- and p-type nanowires as electronic channels that are proton-gated by electron-beam patterned Nafion. We demonstrate inverter circuits with state-of-the-art ion-to-electron transduction performance giving DC gain exceeding 5 and frequency response up to 2 kHz.

Interfacial water morphology in hydrated melanin.

The importance of electrically functional biomaterials is increasing as researchers explore ways to utilise them in novel sensing capacities. It has been recognised that for many of these materials the state of hydration is a key parameter that can heavily affect the conductivity, particularly those that rely upon ionic or proton transport as a key mechanism. However, thus far little attention has been paid to the nature of the water morphology in the hydrated state and the concomitant ionic conductivity.

Melanin, the What, the Why and the How: An Introductory Review for Materials Scientists Interested in Flexible and Versatile Polymers.

Today, western society is facing challenges to create new medical technologies to service an aging population as well as the ever-increasing e-waste of electronic devices and sensors. A key solution to these challenges will be the use of biomaterials and biomimetic systems. One material that has been receiving serious attention for its biomedical and device applications is eumelanin.

Shedding Light on the Free Radical Nature of Sulfonated Melanins.

Melanin, an important class of natural pigment found in the human body, has stood out as a promising bioelectronic material due to its rather unique collection of electrical properties and biocompatibility. Among the available melanin derivatives, the sulfonated form has proven to not only be able to produce homogeneous device quality thin films with excellent adhesion, even on hydrophobic surfaces, but also to act as an ion to electron transducing element. It has recently been shown that the transport physics (and dominant carrier generation) may be related to a semiquinone free radical species in these materials.

Engineering proton conductivity in melanin using metal doping.

Long range electrical conduction in biomaterials is an increasingly active area of research, which includes systems such as the conductive pili, proteins, biomacromolecules, biocompatible conductive polymers and their derivatives. One material of particular interest, the human skin pigment melanin, is a long range proton conductor and recently demonstrated as capable of proton-to-electron transduction in a solid-state electrochemical transistor platform. In this work, a novel "doping strategy" is proposed to enhance and control melanin's proton conductivity, potentially enhancing its utility as a transducing material.

Abduction treatment in stable hip dysplasia does not alter the acetabular growth: results of a randomized clinical trial.

Background The effect of bracing over natural history of stable dysplastic hips is not well known. This multicenter randomized trial aimed at objectifying the effect of abduction treatment versus active surveillance in infants of 3 to 4 months of age. Methods Patients were randomized to either Pavlik harness or active surveillance group.

Redox chemistry in the pigment eumelanin as a function of temperature using broadband dielectric spectroscopy.

Conductive biomolecular systems are investigated for their promise of new technologies. One biomolecular material that has garnered interest for device applications is eumelanin. Its unusual properties have led to its incorporation in a wide set of platforms including transistor devices and batteries.

A Prospective, Randomized, Multicenter Study Comparing Silicated Calcium Phosphate versus BMP-2 Synthetic Bone Graft in Posterolateral Instrumented Lumbar Fusion for Degenerative Spinal Disorders.

Study Design: A prospective, Phase IV, multicenter, randomized study.

Objective: The aim of this study was to compare vertebral fusion success rates following posterolateral fusion [(PLF)/posterolateral intertransverse fusion (PITF)] surgery. The surgical procedure combined posterior lumbar interbody fusion (PLIF) and PLF with internal fixation over one or two levels using silicated calcium phosphate (SiCaP) or bone morphogenetic protein (BMP)-2 as graft material in patients with a degenerative disorder of the lumbar spine.

The photoreactive free radical in eumelanin.

Melanin is the primary photoprotecting pigment in humans as well as being implicated in the development of deadly melanoma. The material also conducts electricity and has thus become a bioelectronic model for proton-to-electron transduction. Central to these phenomena are its spin properties-notably two linked species derived from carbon-centered and semiquinone radicals.

Microbial nanowires - Electron transport and the role of synthetic analogues.

Unlabelled: Electron transfer is central to cellular life, from photosynthesis to respiration. In the case of anaerobic respiration, some microbes have extracellular appendages that can be utilised to transport electrons over great distances. Two model organisms heavily studied in this arena are Shewanella oneidensis and Geobacter sulfurreducens.

[Distal femur fracture in a woman with a lower limb prosthesis.].

Background: People who use a lower limb prosthesis can fracture their distal femur after a trivial fall; however, this kind of fracture is uncommon.

Case Description: A 53-year-old woman with a trans-tibial prosthesis fell in her kitchen. She felt pain just above the socket of the prosthesis, was unable to get up and her knee and leg were swollen.

The structural impact of water sorption on device-quality melanin thin films.

The melanins are a class of pigmentary bio-macromolecules ubiquitous in the biosphere. They possess an intriguing set of physico-chemical properties and have been shown to exhibit hybrid protonic-electronic electrical conductivity, a feature derived from a process termed chemical self-doping driven by the sorption of water. Although the mechanism underlying the electrical conduction has been established, how the sorbed water interacts with the melanin structure at the physical level has not.

Formation of Two-Dimensional Micelles on Graphene: Multi-Scale Theoretical and Experimental Study.

Graphene and related two-dimensional (2D) materials possess outstanding electronic and mechanical properties, chemical stability, and high surface area. However, to realize graphene's potential for a range of applications in materials science and nanotechnology there is a need to understand and control the interaction of graphene with tailored high-performance surfactants designed to facilitate the preparation, manipulation, and functionalization of new graphene systems. Here we report a combined experimental and theoretical study of the surface structure and dynamics on graphene of pyrene-oligoethylene glycol (OEG) -based surfactants, which have previously been shown to disperse carbon nanotubes in water.

Hybrid Nanowire Ion-to-Electron Transducers for Integrated Bioelectronic Circuitry.

A key task in the emerging field of bioelectronics is the transduction between ionic/protonic and electronic signals at high fidelity. This is a considerable challenge since the two carrier types exhibit intrinsically different physics and are best supported by very different materials types-electronic signals in inorganic semiconductors and ionic/protonic signals in organic or bio-organic polymers, gels, or electrolytes. Here we demonstrate a new class of organic-inorganic transducing interface featuring semiconducting nanowires electrostatically gated using a solid proton-transporting hygroscopic polymer.

A cohort study of elderly people in Bloemfontein, South Africa, to determine health-related quality of life and functional abilities.

Background: An ageing population has become an issue of global importance. According to statistics, the number of people aged ≥60 years will outnumber children <5 years by 2020.

Objective: To identify chronic and comorbid diseases that contribute to reduced quality of life (QoL) and functional ability in elderly people living in nursing homes in Bloemfontein, Free State, South Africa (SA).

Heavy Water as a Probe of the Free Radical Nature and Electrical Conductivity of Melanin.

Melanins are pigmentary macromolecules found in many locations throughout nature including plants and vertebrate animals. It was recently proposed that the predominant brown-black pigment eumelanin is a mixed ionic-electronic conductor which has led to renewed interest in its basic properties as a model bioelectronic material. This exotic hybrid electrical behavior is strongly dependent upon hydration and is closely related to the free radical content of melanin which is believed to be a mixed population of two species: the semiquinone (SQ) and a carbon-centered radical (CCR).

Hydration-controlled X-band EPR spectroscopy: a tool for unravelling the complexities of the solid-state free radical in eumelanin.

Melanin, the human skin pigment, is found everywhere in nature. Recently it has gained significant attention for its potential bioelectronic properties. However, there remain significant obstacles in realizing its electronic potential, in particular, the identity of the solid-state free radical in eumelanin, which has been implicated in charge transport.