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Materials, Volume 5, Issue 12 (December 2012), Pages 2439-3005

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Open AccessArticle Comparison of Fatigue Properties and Fatigue Crack Growth Rates of Various Implantable Metals
Materials 2012, 5(12), 2981-3005; https://doi.org/10.3390/ma5122981
Received: 24 October 2012 / Revised: 3 December 2012 / Accepted: 14 December 2012 / Published: 19 December 2012
Cited by 13 | PDF Full-text (1396 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The fatigue strength, effects of a notch on the fatigue strength, and fatigue crack growth rate of Ti-15Zr-4Nb-4Ta alloy were compared with those of other implantable metals. Zr, Nb, and Ta are important alloying elements for Ti alloys for attaining superior long-term corrosion
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The fatigue strength, effects of a notch on the fatigue strength, and fatigue crack growth rate of Ti-15Zr-4Nb-4Ta alloy were compared with those of other implantable metals. Zr, Nb, and Ta are important alloying elements for Ti alloys for attaining superior long-term corrosion resistance and biocompatibility. The highly biocompatible Ti-15Zr-4Nb-4Ta alloy exhibited an excellent balance between strength and ductility. Its notched tensile strength was much higher than that of a smooth specimen. The strength of 20% cold-worked commercially pure (C.P.) grade 4 Ti was close to that of Ti alloy. The tension-to-tension fatigue strength of an annealed Ti-15Zr-4Nb-4Ta rod at 107 cycles was approximately 740 MPa. The fatigue strength of this alloy was much improved by aging treatment after solution treatment. The fatigue strengths of C.P. grade 4 Ti and stainless steel were markedly improved by 20% cold working. The fatigue strength of Co-Cr-Mo alloy was markedly increased by hot forging. The notch fatigue strengths of 20% cold-worked C.P. grade 4 Ti, and annealed and aged Ti-15Zr-4Nb-4Ta, and annealed Ti-6Al-4V alloys were less than those of the smooth specimens. The fatigue crack growth rate of Ti-15Zr-4Nb-4Ta was the same as that of Ti-6Al-4V. The fatigue crack growth rate in 0.9% NaCl was the same as that in air. Stainless steel and Co-Cr-Mo-Ni-Fe alloy had a larger stress-intensity factor range (ΔK) than Ti alloy. Full article
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Open AccessReview Characterization of Nanocomposites by Thermal Analysis
Materials 2012, 5(12), 2960-2980; https://doi.org/10.3390/ma5122960
Received: 10 September 2012 / Revised: 3 December 2012 / Accepted: 10 December 2012 / Published: 19 December 2012
Cited by 59 | PDF Full-text (305 KB) | HTML Full-text | XML Full-text
Abstract
In materials research, the development of polymer nanocomposites (PN) is rapidly emerging as a multidisciplinary research field with results that could broaden the applications of polymers to many different industries. PN are polymer matrices (thermoplastics, thermosets or elastomers) that have been reinforced with
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In materials research, the development of polymer nanocomposites (PN) is rapidly emerging as a multidisciplinary research field with results that could broaden the applications of polymers to many different industries. PN are polymer matrices (thermoplastics, thermosets or elastomers) that have been reinforced with small quantities of nano-sized particles, preferably characterized by high aspect ratios, such as layered silicates and carbon nanotubes. Thermal analysis (TA) is a useful tool to investigate a wide variety of properties of polymers and it can be also applied to PN in order to gain further insight into their structure. This review illustrates the versatile applications of TA methods in the emerging field of polymer nanomaterial research, presenting some examples of applications of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA) and thermal mechanical analysis (TMA) for the characterization of nanocomposite materials. Full article
(This article belongs to the Special Issue Advances in Multifunctional Materials)
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Open AccessReview Recent Progress in Surface Modification of Polyvinyl Chloride
Materials 2012, 5(12), 2937-2959; https://doi.org/10.3390/ma5122937
Received: 26 September 2012 / Revised: 11 December 2012 / Accepted: 11 December 2012 / Published: 18 December 2012
Cited by 23 | PDF Full-text (1072 KB) | HTML Full-text | XML Full-text
Abstract
Surface modification of polymers has become a vibrant field of research on account of a myriad of rationales which stimulated numerous efforts. The current paper serves as a condensed survey of the advances made through different approaches adopted for tuning the surface properties
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Surface modification of polymers has become a vibrant field of research on account of a myriad of rationales which stimulated numerous efforts. The current paper serves as a condensed survey of the advances made through different approaches adopted for tuning the surface properties of polyvinyl chloride as a homopolymer extensively used on a large scale. Though it does not address all challenges involved, this paper communicates and highlights, through concise discussion, the findings of the efforts undertaken in recent decades. It is ultimately concluded with a perspective of the huge capacities and promising future directions. Full article
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Open AccessArticle Dispersion of Pt Nanoparticle-Doped Reduced Graphene Oxide Using Aniline as a Stabilizer
Materials 2012, 5(12), 2927-2936; https://doi.org/10.3390/ma5122927
Received: 17 September 2012 / Revised: 22 November 2012 / Accepted: 7 December 2012 / Published: 18 December 2012
Cited by 15 | PDF Full-text (2456 KB) | HTML Full-text | XML Full-text
Abstract
In this study, a simple one-step method was developed to load small-sized Pt nanoparticles (3.1 ± 0.3 nm) in large quantities (50 wt %) on aniline-functionalized and reduced graphene oxide (r-fGO). In the process, an ethylene glycol solution and aniline-functionalized moiety play the
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In this study, a simple one-step method was developed to load small-sized Pt nanoparticles (3.1 ± 0.3 nm) in large quantities (50 wt %) on aniline-functionalized and reduced graphene oxide (r-fGO). In the process, an ethylene glycol solution and aniline-functionalized moiety play the roles of reducing agent and stabilizer for the Pt nanoparticles, respectively, without damaging the graphite structures of the r-fGO. The Pt nanoparticles loading on the surface of r-fGO with uniform dispersion have a great effect on the electrical conductivity. Full article
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Open AccessArticle Preparation, Characterization and Release of Urea from Wheat Gluten Electrospun Membranes
Materials 2012, 5(12), 2903-2916; https://doi.org/10.3390/ma5122903
Received: 6 November 2012 / Revised: 11 December 2012 / Accepted: 11 December 2012 / Published: 18 December 2012
Cited by 16 | PDF Full-text (839 KB) | HTML Full-text | XML Full-text
Abstract
Homogeneous and thin porous membranes composed of oriented fibers were obtained from wheat gluten (WG) using the electrospinning technique. SEM micrographs showed an asymmetric structure and some porosity, which, in addition to a small thickness of 40 mm, are desirable characteristics for the
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Homogeneous and thin porous membranes composed of oriented fibers were obtained from wheat gluten (WG) using the electrospinning technique. SEM micrographs showed an asymmetric structure and some porosity, which, in addition to a small thickness of 40 mm, are desirable characteristics for the membranes’ potential application in release systems. The membranes were loaded with urea to obtain pastilles. FT-IR and DSC studies confirmed the existence of interactions via hydrogen bonding between urea and WG proteins. The pastilles were studied as prolonged-released systems of urea in water. The release of urea during the first 10 min was very fast; then, the rate of release decreased as it reached equilibrium at 300 min, with a total of »98% urea released. TGA analysis showed that the release system obtained is thermally stable up to a temperature of 117 °C. It was concluded that a prolonged-release system of urea could be satisfactorily produced using WG fibers obtained by electrospinning for potential application in agricultural crops. Full article
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Open AccessArticle Optimization of the GaAs-on-Si Substrate for Microelectromechanical Systems (MEMS) Sensor Application
Materials 2012, 5(12), 2917-2926; https://doi.org/10.3390/ma5122917
Received: 24 October 2012 / Revised: 4 December 2012 / Accepted: 10 December 2012 / Published: 17 December 2012
Cited by 7 | PDF Full-text (1260 KB) | HTML Full-text | XML Full-text
Abstract
Resonant Tunneling Diodes (RTD) and High Electron Mobility Transistor (HEMT) based on GaAs, as the piezoresistive sensing element, exhibit extremely high sensitivity in the MEMS sensors based on GaAs. To further expand their applications to the fields of MEMS sensors based on Si,
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Resonant Tunneling Diodes (RTD) and High Electron Mobility Transistor (HEMT) based on GaAs, as the piezoresistive sensing element, exhibit extremely high sensitivity in the MEMS sensors based on GaAs. To further expand their applications to the fields of MEMS sensors based on Si, we have studied the optimization of the GaAs epitaxy layers on Si wafers. Matching superlattice and strain superlattice were used, and the surface defect density can be improved by two orders of magnitude. Combing with the Raman spectrum, the residual stress was characterized, and it can be concluded from the experimental results that the residual stress can be reduced by 50%, in comparison with the original substrate. This method gives us a solution to optimize the epitaxy GaAs layers on Si substrate, which will also optimize our future process of integration RTD and HEMT based on GaAs on Si substrate for the MEMS sensor applications. Full article
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Open AccessReview A Review: Fundamental Aspects of Silicate Mesoporous Materials
Materials 2012, 5(12), 2874-2902; https://doi.org/10.3390/ma5122874
Received: 15 October 2012 / Revised: 23 November 2012 / Accepted: 29 November 2012 / Published: 17 December 2012
Cited by 179 | PDF Full-text (1985 KB) | HTML Full-text | XML Full-text
Abstract
Silicate mesoporous materials have received widespread interest because of their potential applications as supports for catalysis, separation, selective adsorption, novel functional materials, and use as hosts to confine guest molecules, due to their extremely high surface areas combined with large and uniform pore
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Silicate mesoporous materials have received widespread interest because of their potential applications as supports for catalysis, separation, selective adsorption, novel functional materials, and use as hosts to confine guest molecules, due to their extremely high surface areas combined with large and uniform pore sizes. Over time a constant demand has developed for larger pores with well-defined pore structures. Silicate materials, with well-defined pore sizes of about 2.0–10.0 nm, surpass the pore-size constraint (<2.0 nm) of microporous zeolites. They also possess extremely high surface areas (>700 m2 g−1) and narrow pore size distributions. Instead of using small organic molecules as templating compounds, as in the case of zeolites, long chain surfactant molecules were employed as the structure-directing agent during the synthesis of these highly ordered materials. The structure, composition, and pore size of these materials can be tailored during synthesis by variation of the reactant stoichiometry, the nature of the surfactant molecule, the auxiliary chemicals, the reaction conditions, or by post-synthesis functionalization techniques. This review focuses mainly on a concise overview of silicate mesoporous materials together with their applications. Perusal of the review will enable researchers to obtain succinct information about microporous and mesoporous materials. Full article
(This article belongs to the Special Issue Advances in Mesoporous Materials)
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Open AccessCorrection Correction: Effect of AlF3 on the Density and Elastic Properties of Zinc Tellurite Glass Systems. Materials 2012, 5, 1361-1372.
Materials 2012, 5(12), 2872-2873; https://doi.org/10.3390/ma5122872
Received: 13 December 2012 / Accepted: 13 December 2012 / Published: 13 December 2012
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Abstract
Due to an oversight, the data of the last column “Vs” in Table 1 was missing in the original version of this article [1]. [...] Full article
Open AccessReview The Toxic Effects and Mechanisms of CuO and ZnO Nanoparticles
Materials 2012, 5(12), 2850-2871; https://doi.org/10.3390/ma5122850
Received: 1 August 2012 / Revised: 24 September 2012 / Accepted: 3 December 2012 / Published: 13 December 2012
Cited by 193 | PDF Full-text (898 KB) | HTML Full-text | XML Full-text
Abstract
Recent nanotechnological advances suggest that metal oxide nanoparticles (NPs) have been expected to be used in various fields, ranging from catalysis and opto-electronic materials to sensors, environmental remediation, and biomedicine. However, the growing use of NPs has led to their release into environment
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Recent nanotechnological advances suggest that metal oxide nanoparticles (NPs) have been expected to be used in various fields, ranging from catalysis and opto-electronic materials to sensors, environmental remediation, and biomedicine. However, the growing use of NPs has led to their release into environment and the toxicity of metal oxide NPs on organisms has become a concern to both the public and scientists. Unfortunately, there are still widespread controversies and ambiguities with respect to the toxic effects and mechanisms of metal oxide NPs. Comprehensive understanding of their toxic effect is necessary to safely expand their use. In this review, we use CuO and ZnO NPs as examples to discuss how key factors such as size, surface characteristics, dissolution, and exposure routes mediate toxic effects, and we describe corresponding mechanisms, including oxidative stress, coordination effects and non-homeostasis effects. Full article
(This article belongs to the Special Issue Nanotoxicology)
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Open AccessArticle Pulmonary Inflammation of Well-Dispersed Multi-Wall Carbon Nanotubes Following Intratracheal Instillation: Toxicity by Fiber of 1–5 µm in Length
Materials 2012, 5(12), 2833-2849; https://doi.org/10.3390/ma5122833
Received: 3 September 2012 / Revised: 9 November 2012 / Accepted: 11 December 2012 / Published: 13 December 2012
Cited by 4 | PDF Full-text (1330 KB) | HTML Full-text | XML Full-text
Abstract
The pulmonary toxicity of multi-wall carbon nanotubes (MWCNT) were examined by intratracheal instillation. We prepared a well-dispersed MWCNT dispersion including MWCNTs of 3.71 µm geometric average length. The fiber length of most of the MWCNTs in the dispersion was 10 µm or less.
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The pulmonary toxicity of multi-wall carbon nanotubes (MWCNT) were examined by intratracheal instillation. We prepared a well-dispersed MWCNT dispersion including MWCNTs of 3.71 µm geometric average length. The fiber length of most of the MWCNTs in the dispersion was 10 µm or less. The MWCNT dispersion was administered to rat lung by single intratracheal instillation at doses of 0.2 mg and 0.6 mg/rat. Bronchoalveolar lavage fluid (BALF) was collected at 3 days, 1 week, 1 month, 3 months, and 6 months after instillation. The influences of the longer MWCNTs on the induction of inflammation and oxidative stress were examined by the number of neutrophils, cytokine induced neutrophil chemoattractant-1 (CINC-1), CINC-2, CINC-3 and HO-1 in the BALF. Additionally, ho-1 gene expression in the lung was examined. The intratracheal instillation of MWCNT induced transient inflammation dose dependently in the lung. The number of neutrophils was highest at 3 days after instillation and then decreased. However, the neutrophils in the MWCNT administered animals tended to be higher than in the control group until 3 months after instillation. The CINC-1 and CINC-2 concentrations in the BALF increased at 1 month after instillation. There were no significant differences in CINC-3 and HO-1 between the MWCNT administered animals and the control animals. These results revealed that the MWCNTs of 1–10 µm in length induced persistent inflammation in rat lung. There were no remarkable differences between the MWCNTs in the present study and previously reported, shorter MWCNTs prepared from “the same” raw MWCNT material. Full article
(This article belongs to the Special Issue Nanotoxicology)
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Open AccessArticle Growth of High-Density Zinc Oxide Nanorods on Porous Silicon by Thermal Evaporation
Materials 2012, 5(12), 2817-2832; https://doi.org/10.3390/ma5122817
Received: 29 October 2012 / Revised: 28 November 2012 / Accepted: 6 December 2012 / Published: 13 December 2012
Cited by 31 | PDF Full-text (1563 KB) | HTML Full-text | XML Full-text
Abstract
The formation of high-density zinc oxide (ZnO) nanorods on porous silicon (PS) substrates at growth temperatures of 600–1000 °C by a simple thermal evaporation of zinc (Zn) powder in the presence of oxygen (O2) gas was systematically investigated. The high-density growth
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The formation of high-density zinc oxide (ZnO) nanorods on porous silicon (PS) substrates at growth temperatures of 600–1000 °C by a simple thermal evaporation of zinc (Zn) powder in the presence of oxygen (O2) gas was systematically investigated. The high-density growth of ZnO nanorods with (0002) orientation over a large area was attributed to the rough surface of PS, which provides appropriate planes to promote deposition of Zn or ZnOx seeds as nucleation sites for the subsequent growth of ZnO nanorods. The geometrical morphologies of ZnO nanorods are determined by the ZnOx seed structures, i.e., cluster or layer structures. The flower-like hexagonal-faceted ZnO nanorods grown at 600 °C seem to be generated from the sparsely distributed ZnOx nanoclusters. Vertically aligned hexagonal-faceted ZnO nanorods grown at 800 °C may be inferred from the formation of dense arrays of ZnOx clusters. The formation of disordered ZnO nanorods formed at 1000 °C may due to the formation of a ZnOx seed layer. The growth mechanism involved has been described by a combination of self-catalyzed vapor-liquid-solid (VLS) and vapor-solid (VS) mechanism. The results suggest that for a more precise study on the growth of ZnO nanostructures involving the introduction of seeds, the initial seed structures must be taken into account given their significant effects. Full article
(This article belongs to the Special Issue Compound Semiconductor Materials)
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Open AccessRetraction Retraction: Heidari, A.; Vedad, S.; Heidari, N.; Ghorbani, M. Flux Dynamics in Y358 Superconductors. Materials 2012, 5, 882-888.
Materials 2012, 5(12), 2816; https://doi.org/10.3390/ma5122816
Received: 11 December 2012 / Accepted: 11 December 2012 / Published: 12 December 2012
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Abstract
It has been brought to our attention by a reader of Materials that substantial portions of this article [1] have been translated from another publication [2] without credit. After confirming this to be the case with the authors, we have determined that indeed
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It has been brought to our attention by a reader of Materials that substantial portions of this article [1] have been translated from another publication [2] without credit. After confirming this to be the case with the authors, we have determined that indeed this manuscript clearly violates our policy of originality of all material submitted for publication and the generally accepted ethics of scientific publication. Consequently, the Editorial Team and Publisher have determined that it should be retracted. We apologize for any inconvenience this may cause. [...] Full article
Open AccessReview Holographic Gratings for Slow-Neutron Optics
Materials 2012, 5(12), 2788-2815; https://doi.org/10.3390/ma5122788
Received: 22 August 2012 / Revised: 27 September 2012 / Accepted: 4 December 2012 / Published: 12 December 2012
Cited by 9 | PDF Full-text (3968 KB) | HTML Full-text | XML Full-text
Abstract
Recent progress in the development of holographic gratings for neutron-optics applications is reviewed. We summarize the properties of gratings recorded in deuterated (poly)methylmethacrylate, holographic polymer-dispersed liquid crystals and nanoparticle-polymer composites revealed by diffraction experiments with slow neutrons. Existing and anticipated neutron-optical instrumentations based
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Recent progress in the development of holographic gratings for neutron-optics applications is reviewed. We summarize the properties of gratings recorded in deuterated (poly)methylmethacrylate, holographic polymer-dispersed liquid crystals and nanoparticle-polymer composites revealed by diffraction experiments with slow neutrons. Existing and anticipated neutron-optical instrumentations based on holographic gratings are discussed. Full article
(This article belongs to the Special Issue Advanced Materials for Modern Holographic Applications)
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Open AccessArticle Topographical Anisotropy and Wetting of Ground Stainless Steel Surfaces
Materials 2012, 5(12), 2773-2787; https://doi.org/10.3390/ma5122773
Received: 27 September 2012 / Revised: 14 November 2012 / Accepted: 4 December 2012 / Published: 12 December 2012
Cited by 4 | PDF Full-text (1338 KB) | HTML Full-text | XML Full-text
Abstract
Microscopic and physico-chemical methods were used for a comprehensive surface characterization of different mechanically modified stainless steel surfaces. The surfaces were analyzed using high-resolution confocal microscopy, resulting in detailed information about the topographic properties. In addition, static water contact angle measurements were carried
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Microscopic and physico-chemical methods were used for a comprehensive surface characterization of different mechanically modified stainless steel surfaces. The surfaces were analyzed using high-resolution confocal microscopy, resulting in detailed information about the topographic properties. In addition, static water contact angle measurements were carried out to characterize the surface heterogeneity of the samples. The effect of morphological anisotropy on water contact angle anisotropy was investigated. The correlation between topography and wetting was studied by means of a model of wetting proposed in the present work, that allows quantifying the air volume of the interface water drop-stainless steel surface. Full article
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Open AccessArticle An Ultrasensitive Electrochemical Immunosensor for Alpha-Fetoprotein Using an Envision Complex-Antibody Copolymer as a Sensitive Label
Materials 2012, 5(12), 2757-2772; https://doi.org/10.3390/ma5122757
Received: 21 August 2012 / Revised: 15 November 2012 / Accepted: 6 December 2012 / Published: 11 December 2012
Cited by 21 | PDF Full-text (902 KB) | HTML Full-text | XML Full-text
Abstract
A novel strategy is presented for sensitive detection of alfa-fetoprotein (AFP), using a horseradish peroxidase (HRP)-functionalized Envision antibody complex (EVC) as the label. The Envision-AFP signal antibody copolymer (EVC-AFP Ab2) was composed of a dextran amine skeleton anchoring more than 100 molecules of
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A novel strategy is presented for sensitive detection of alfa-fetoprotein (AFP), using a horseradish peroxidase (HRP)-functionalized Envision antibody complex (EVC) as the label. The Envision-AFP signal antibody copolymer (EVC-AFP Ab2) was composed of a dextran amine skeleton anchoring more than 100 molecules of HRP and 15 molecules of secondary antibody, and acted as a signal tag in the immunosensor. The sensor was constructed using the following steps: First, gold electrode (GE) was modified with nano-gold (AuNPs) by electro-deposition in HAuCl4 solution. The high affinity of the AuNPs surface facilitates direct formation of a self-assembled thiolated protein G layer. Next, the coated GE was incubated in a solution of AFP capture antibody (AFP Ab1); these antibodies attach to the thiolated protein G layer through their non-antigenic regions, leaving the antigen binding sites for binding of target analyte. Following a sandwich immunoreaction, an EVC-AFP Ab2-AFP-AFP Ab1 immunocomplex was formed on the electrode surface, allowing large amounts of HRP on the complex to produce an amplified electrocatalytic current of hydroquinone (HQ) in the presence of hydrogen peroxide (H2O2). Highly amplified detection was achieved, with a detection limit of 2 pg/mL and a linear range of 0.005–0.2 ng/mL for AFP in 10 μL undiluted serum; this is near or below the normal levels of most cancer biomarker proteins in human serum. Measurements of AFP in the serum of cancer patients correlated strongly with standard enzyme-linked immunosorbent assays. These easily fabricated EVC-modified immunosensors show excellent promise for future fabrication of bioelectronic arrays. By varying the target biomolecules, this technique may be easily extended for use with other immunoassays, and thus represents a versatile design route. Full article
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