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1.
J Health Commun ; 28(sup2): 49-60, 2023 10 31.
Artículo en Inglés | MEDLINE | ID: mdl-38146161

RESUMEN

Misinformation can decrease public confidence in vaccines, and reduce vaccination intent and uptake. One strategy for countering these negative impacts comes from inoculation theory. Similar to biological vaccination, inoculation theory posits that exposure to a weakened form of misinformation can develop cognitive immunity, reducing the likelihood of being misled. Online games offer an interactive, technology-driven, and scalable solution using an active form of inoculation that engages and incentivizes players to build resilience against misinformation. We document the development of the critical thinking game Cranky Uncle Vaccine. The game applies research findings from inoculation theory, critical thinking, humor in science communication, and serious games. The game content was iterated through a series of co-design workshops in Kampala (Uganda), Kitale (Kenya), and Kigali (Rwanda). Workshop participants offered feedback on cartoon character design, gameplay experience, and the game's content, helping to make the game more culturally relevant and avoid unintended consequences in East African countries. Our co-design methodology offers an approach for further adaptation of the Cranky Uncle Vaccine game to other regions, as well as a template for developing locally relevant interventions to counter future infodemics.


Asunto(s)
Comunicación , Vacunas , Humanos , Kenia , Uganda , Rwanda
2.
FASEB J ; 35(1): e21194, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33337553

RESUMEN

Synapses are the fundamental structural unit by which neurons communicate. An orchestra of proteins regulates diverse synaptic functions, including synapse formation, maintenance, and elimination-synapse homeostasis. Some proteins of the larger C1q super-family are synaptic organizers involved in crucial neuronal processes in various brain regions. C1Q-like (C1QL) proteins bind to the adhesion G protein-coupled receptor B3 (ADGRB3) and act at synapses in a subset of circuits. To investigate the hypothesis that the secreted C1QL proteins mediate tripartite trans-synaptic adhesion complexes, we conducted an in vivo interactome study and identified new binding candidates. We demonstrate that C1QL3 mediates a novel cell-cell adhesion complex involving ADGRB3 and two neuronal pentraxins, NPTX1 and NPTXR. Analysis of single-cell RNA-Seq data from the cerebral cortex shows that C1ql3, Nptx1, and Nptxr are highly co-expressed in the same excitatory neurons. Thus, our results suggest the possibility that in vivo the three co-expressed proteins are presynaptically secreted and form a complex capable of binding to postsynaptically localized ADGRB3, thereby creating a novel trans-synaptic adhesion complex. Identifying new binding partners for C1QL proteins and deciphering their underlying molecular principles will accelerate our understanding of their role in synapse organization.


Asunto(s)
Proteína C-Reactiva/metabolismo , Complemento C1q/metabolismo , Proteínas de la Membrana/metabolismo , Complejos Multiproteicos/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Neuronas/metabolismo , Sinapsis/metabolismo , Animales , Proteína C-Reactiva/genética , Adhesión Celular/genética , Complemento C1q/genética , Masculino , Proteínas de la Membrana/genética , Ratones , Complejos Multiproteicos/genética , Proteínas del Tejido Nervioso/genética , Sinapsis/genética
3.
Anal Chem ; 85(7): 3521-5, 2013 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-23461486

RESUMEN

We describe a solid state electrode structure based on a biologically derived proton-active redox center, riboflavin (RFN). The redox reaction of RFN is a pH-dependent process that requires no water. The electrode was fabricated using our previously described 'stuffing' method to entrap RFN into vapor phase polymerized poly(3,4-ethylenedioxythiophene). The electrode is shown to be capable of measuring the proton activity in the form of an effective pH over a range of different water contents including nonaqueous systems and ionic liquids (ILs). This demonstrates that the entrapment of the redox center facilitates direct electron communication with the polymer. This work provides a miniaturizable system to determine pH (effective) in nonaqueous systems as well as in ionic liquids. The ability to measure pH (effective) is an important step toward the ability to customize ILs with suitable pH (effective) for catalytic reactions and biotechnology applications such as protein preservation.

4.
ACS Nano ; 17(18): 18470-18480, 2023 09 26.
Artículo en Inglés | MEDLINE | ID: mdl-37669408

RESUMEN

Self-assembling virus-like particles (VLPs) can tolerate a wide degree of genetic and chemical manipulation to their capsid protein to display a foreign molecule polyvalently. We previously reported the successful incorporation of foreign peptide sequences in the junction loop and onto the C-terminus of PP7 dimer VLPs, as these regions are accessible for surface display on assembled capsids. Here, we report the implementation of a library-based approach to test the assembly tolerance of PP7 dimer capsid proteins to insertions or terminal extensions of randomized 15-mer peptide sequences. By performing two iterative rounds of assembly-based selection, we evaluated the degree of favorability of all 20 amino acids at each of the 15 randomized positions. Deep sequencing analysis revealed a distinct preference for the inclusion of hydrophilic peptides and negatively charged amino acids (Asp and Glu) and the exclusion of positively charged peptides and bulky and hydrophobic amino acid residues (Trp, Phe, Tyr, and Cys). Within the libraries tested here, we identified 4000 to 22,000 unique 15-mer peptide sequences that can successfully be displayed on the surface of the PP7 dimer capsid. Overall, the use of small initial libraries consisting of no more than a few million members yielded a significantly larger number of unique and assembly-competent VLP sequences than have been previously characterized for this class of nucleoprotein particle.


Asunto(s)
Aminoácidos , Péptidos , Secuencia de Aminoácidos , Cápside , Proteínas de la Cápside/genética , Polímeros
5.
PLoS One ; 16(5): e0251412, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33979385

RESUMEN

Hearing depends on the transduction of sounds into neural signals by the inner hair cells of the cochlea. Cochleae also have outer hair cells with unique electromotile properties that increase auditory sensitivity, but they are particularly susceptible to damage by intense noise exposure, ototoxic drugs, and aging. Although the outer hair cells have synapses on afferent neurons that project to the brain, the function of this neuronal circuit is unclear. Here, we created a novel mouse allele that inserts a fluorescent reporter at the C1ql1 locus which revealed gene expression in the outer hair cells and allowed creation of outer hair cell-specific C1ql1 knockout mice. We found that C1ql1 expression in outer hair cells corresponds to areas with the most sensitive frequencies of the mouse audiogram, and that it has an unexpected adolescence-onset developmental timing. No expression was observed in the inner hair cells. Since C1QL1 in the brain is made by neurons, transported anterogradely in axons, and functions in the synaptic cleft, C1QL1 may serve a similar function at the outer hair cell afferent synapse. Histological analyses revealed that C1ql1 conditional knockout cochleae may have reduced outer hair cell afferent synapse maintenance. However, auditory behavioral and physiological assays did not reveal a compelling phenotype. Nonetheless, this study identifies a potentially useful gene expressed in the cochlea and opens the door for future studies aimed at elucidating the function of C1QL1 and the function of the outer hair cell and its afferent neurons.


Asunto(s)
Cóclea/metabolismo , Complemento C1q/metabolismo , Células Ciliadas Auditivas Externas/metabolismo , Alelos , Animales , Complemento C1q/genética , Ratones , Ratones Noqueados , Sinapsis/metabolismo
6.
Emerg Med Australas ; 33(3): 534-540, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33586331

RESUMEN

OBJECTIVE: To assess changes in presentations to EDs during the COVID-19 pandemic lockdown in the Southern Region of New Zealand. METHODS: We conducted a retrospective audit of patients attending EDs in the Southern District Health Board (SDHB), from 1 March to 13 May 2020. We made comparisons with attendances during the same period in 2019. The 2020 study period included 'pre-lockdown' (1 March-25 March), 'level 4 (strict) lockdown' (26 March-27 April) and 'level 3 (eased) lockdown' (28 April-13 May). RESULTS: Patient volumes reduced in all SDHB EDs during levels 4 and 3, mostly representing a loss of low acuity patients (Australasian Triage Scale 3, 4 and 5), although high-acuity presentations also declined. Average patient age increased by 5 years; however, the proportions of sexes and ethnicities did not change. Presentations of cerebrovascular accidents and appendicitis did not change significantly. Trauma, mental health, acute coronary syndrome and infectious respiratory presentations decreased significantly during level 4, and infectious respiratory presentations decreased further in level 3. CONCLUSIONS: Within the SDHB, patient volumes reduced during levels 4 and 3 of our lockdown, with reduced low-acuity presentations. High-acuity patient numbers also declined. Trauma, mental health, alcohol-related, infectious respiratory and acute coronary syndrome presentations declined while cerebrovascular accident and appendicitis numbers showed little to no change.

7.
Macromol Rapid Commun ; 31(14): 1293-7, 2010 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-21567527

RESUMEN

Glucose oxidase (GOx) is an important enzyme with great potential application for enzymatic sensing of glucose, in implantable biofuel cells for powering of medical devices in vivo and for large-scale biofuel cells for distributed energy generation. For these applications, immobilisation of GOx and direct transfer of electrons from the enzyme to an electrode material is required. This paper describes synthesis of conducting polymer (CP) structures in which GOx has been entrained such that direct electron transfer is possible between GOx and the CP. CP/enzyme composites prepared by other means show no evidence of such "wiring". These materials therefore show promise for mediator-less electronic connection of GOx into easily produced electrodes for biosensing or biofuel cell applications.

8.
Adv Mater ; 21(43): 4393-7, 2009 Nov 20.
Artículo en Inglés | MEDLINE | ID: mdl-26042951

RESUMEN

A biosynthetic platform composed of a conducting polypyrrole sheet embedded with unidirectional biodegradable polymer fibers is described (see image; scale bar = 50 µm). Such hybrid systems can promote rapid directional nerve growth for neuro-regenerative scaffolds and act as interfaces between the electronic circuitry of medical bionic devices and the nervous system.

9.
Adv Mater ; 21(43)2009 Nov 20.
Artículo en Inglés | MEDLINE | ID: mdl-26042954

RESUMEN

Effective functional innervation of medical bionic devices, as well as re-innervation of target tissue in nerve and spinal cord injuries, requires a platform that can stimulate and orientate neural growth. Gordon Wallace and co-workers report on p. 4393 that conducting and nonconducting biodegradable polymers show excellent potential as suitable hybrid substrata for neural regeneration and may form the basis of electrically active conduits designed to accelerate nerve repair.

10.
Acta Biomater ; 94: 585-596, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31129362

RESUMEN

An artificial cornea or keratoprosthesis requires high mechanical strength, good biocompatibility, and sufficient wear and corrosion resistance to withstand the hostile environment. We report a reduced graphene oxide-reinforced titania-based composite for this application. Graphene oxide nanoparticles (GO) and liquid crystalline graphene oxide (LCGO) were the graphene precursors and mixed with titanium dioxide (TiO2) powder. The composites reinforced with reduced GO or LCGO were produced through spark plasma sintering (SPS). The mechanical properties (Young's modulus and hardness), wear behaviour and corrosion resistance were studied using nanoindentation, anoidic polarization, long-term corrosion assay in artificial tear fluid and tribology assay in corroboration with atomic force microscopy and scanning electron microscopy. Biocompatibility was assessed by human corneal stromal cell attachment, survival and proliferation, and DNA damages. Sintered composites were implanted into rabbit corneas to assess for in vivo stability and host tissue responses. We showed that reduced graphene/TiO2 hybrids were safe and biocompatible. In particular, the 1% reduced LCGO/TiO2 (1rLCGO/TiO2) composite was mechanically strong, chemically stable, and showed better wear and corrosion resistance than pure titania and other combinations of graphene-reinforced titania. Hence the 1rLCGO/ TiO2 bioceramics can be a potential skirt biomaterial for keratoprosthesis to treat end-stage corneal blindness. STATEMENT OF SIGNIFICANCE: The osteo-odonto-keratoprosthesis (OOKP) is an artificial cornea procedure used to restore vision in end-stage corneal diseases, however it is contraindicated in young subjects, patients with advanced imflammatory diseases and posterior segment complications. Hence, there is a need of an improved keratoprosthesisskirt material with high mechanical and chemical stability, wear resistance and tissue integration ability. Our study characterized a reduced graphene oxide-reinforced titania-based biomaterial, which demonstrated strong mechanical strength, wear and corrosion resistance, and was safe and biocompatible to human corneal stromal cells. In vivo implantation to rabbit corneas did not cause any immune and inflammation outcomes. In conclusion, this invention is a potential keratoprosthesis skirt biomaterial to withstand the hostile environment in treating end-stage corneal blindness.


Asunto(s)
Córnea , Enfermedades de la Córnea , Grafito/química , Implantes Experimentales , Ensayo de Materiales , Titanio/química , Animales , Córnea/metabolismo , Córnea/patología , Enfermedades de la Córnea/metabolismo , Enfermedades de la Córnea/patología , Enfermedades de la Córnea/cirugía , Humanos , Conejos , Células del Estroma/metabolismo , Células del Estroma/patología
11.
FASEB J ; 21(10): 2312-22, 2007 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-17412999

RESUMEN

Clusterin is an extracellular chaperone present in all disease-associated extracellular amyloid deposits, but its roles in amyloid formation and protein deposition in vivo are poorly understood. The current study initially aimed to characterize the effects of clusterin on amyloid formation in vitro by a panel of eight protein substrates. Two of the substrates (Alzheimer's beta peptide and a PI3-SH3 domain) were then used in further experiments to examine the effects of clusterin on amyloid cytotoxicity and to probe the mechanism of clusterin action. We show that clusterin exerts potent effects on amyloid formation, the nature and extent of which vary greatly with the clusterin:substrate ratio, and provide evidence that these effects are exerted via interactions with prefibrillar species that share common structural features. Proamyloidogenic effects of clusterin appear to be restricted to conditions in which the substrate protein is present at a very large molar excess; under these same conditions, clusterin coincorporates with substrate protein into insoluble aggregates. However, when clusterin is present at much higher but still substoichiometric levels (e.g., a molar ratio of clusterin:substrate=1:10), it potently inhibits amyloid formation and provides substantial cytoprotection. These findings suggest that clusterin is an important element in the control of extracellular protein misfolding.


Asunto(s)
Clusterina/sangre , Ovillos Neurofibrilares/patología , Amiloide/efectos de los fármacos , Amiloide/metabolismo , Animales , Bovinos , Línea Celular Tumoral , Clusterina/aislamiento & purificación , Clusterina/farmacología , Humanos , Microscopía Fluorescente , Neuroblastoma , Ovillos Neurofibrilares/efectos de los fármacos , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Recombinantes de Fusión/farmacología
12.
Biomaterials ; 28(3): 513-23, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17007922

RESUMEN

This research aims to improve the nerve-electrode interface of the cochlear implant using polymer technology to encourage neuron survival, elongation and adhesion to the electrodes. Polypyrrole (Ppy) doped with p-toluene sulphonate (pTS) is an electroactive polymer into which neurotrophin-3 (NT3) can be incorporated. Ppy/pTS+/-NT3 was synthesised over gold electrodes and used as a surface for auditory neuron explant culture. Neurite outgrowth from explants grown on Ppy/pTS was equivalent to tissue culture plastic but improved with the incorporation of NT3 (Ppy/pTS/NT3). Electrical stimulation of Ppy/pTS/NT3 with a biphasic current pulse, as used in cochlear implants, significantly improved neurite outgrowth from explants. Using (125)I-NT3, it was shown that low levels of NT3 passively diffused from Ppy/pTS/NT3 during normal incubation and that electrical stimulation enhanced the release of biologically active NT3 in quantities adequate for neuron survival. Furthermore, Ppy/pTS/NT3 and its constituents were not toxic to auditory neurons and the Ppy/pTS/NT3 coating on gold electrodes did not alter impedance. If applied to the cochlear implant, Ppy/pTS/NT3 will provide a biocompatible, low-impedance substrate for storage and release of NT3 to help protect auditory neurons from degradation after sensorineural hearing loss and encourage neurite outgrowth towards the electrodes.


Asunto(s)
Materiales Biocompatibles/química , Regeneración Nerviosa , Neuritas/metabolismo , Neuronas Aferentes/metabolismo , Neuronas/metabolismo , Neurotrofina 3/química , Polímeros/química , Pirroles/química , Animales , Bencenosulfonatos/química , Impedancia Eléctrica , Electrodos , Femenino , Masculino , Ratas , Ratas Wistar
13.
J Biomed Mater Res A ; 105(12): 3502-3513, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28869708

RESUMEN

The manufacture of mechanically strong and biocompatible titania (TiO2 ) materials is of vital importance for their application as corneal implant skirts. This study was aimed at optimizing the selection of raw powder and sintering conditions for TiO2 ceramics. TiO2 compacts were synthesized from five raw powders, denoted as Altair, Inframat, Alfa, Materion, and Amperit, respectively, by spark plasma sintering using different sintering parameters. The XRD and Raman results confirmed that the anatase TiO2 phase in the Inframat powder had converted completely to rutile TiO2 phase after sintering at 900°C and above. The nanoindentation results indicated that among the five types of TiO2 samples sintered at 1100°C, the Inframat pellets possessed the highest Young's modulus and hardness. Additionally, when Materion samples were employed to study the effects of SPS parameters, a higher sintering temperature in the range of 1100-1300°C decreased the mechanical properties of sintered pellets probably due to the generation of more structural defects. Culture of human corneal stromal fibroblasts on the sintered sample surfaces showed that comparably high cell viability and proliferation were observed on all TiO2 samples except Amperit compared to positive control. Furthermore, cells cultured on Inframat TiO2 sintered in the temperature range of 900-1300°C exhibited viability and formation of focal adhesion complex similar to those on control, and those prepared at 1100°C had significantly higher cell proliferation indices than control. In conclusion, Inframat TiO2 consolidated at 1100°C by SPS was the best formulation for the preparation of mechanically strong and biocompatible Keratoprosthesis skirt. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3502-3513, 2017.


Asunto(s)
Materiales Biocompatibles/química , Córnea/citología , Titanio/química , Proliferación Celular , Supervivencia Celular , Células Cultivadas , Cerámica/química , Módulo de Elasticidad , Femenino , Dureza , Humanos , Ensayo de Materiales , Persona de Mediana Edad , Prótesis e Implantes
14.
J Control Release ; 116(3): 285-94, 2006 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-17112619

RESUMEN

In this study, a neurotrophin delivery system based on an inherently conducting polymer (ICP) has been developed. Direct incorporation of neurotrophin-3 (NT-3) was investigated and controlled release was tested under various electrochemical conditions. The loading capacity and amount of NT-3 released from the polymer was determined using (125)I-labelled NT-3. Electrochemical stimulation of polypyrrole by pulsed voltage, pulsed current or cyclic voltammetry promoted the release of NT-3 at a greater rate than natural diffusion of NT-3. NT-3 was released from polypyrrole as an initial burst in the first 24 h followed by prolonged release over a subsequent 6 days of sampling. The amount of NT-3 incorporated into the polymer could be controlled by varying the polymerisation time, with longer growth periods incorporating more NT-3. The NT-3 release results indicated that the polymers grown for longer released a lower percentage of the incorporated NT-3 compared to the polymers grown for shorter times. Polymer-based neurotrophin delivery systems have the potential to be incorporated into future treatments for nerve injuries to prevent nerve degradation and promote nerve protection.


Asunto(s)
Portadores de Fármacos/química , Neurotrofina 3/administración & dosificación , Neurotrofina 3/química , Polímeros/química , Pirroles/química , Preparaciones de Acción Retardada , Composición de Medicamentos , Electroquímica , Radioisótopos de Yodo , Microscopía Electrónica de Transmisión , Estructura Molecular , Solubilidad , Propiedades de Superficie , Factores de Tiempo
15.
Mater Sci Eng C Mater Biol Appl ; 69: 956-66, 2016 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-27612791

RESUMEN

Transparent bioceramics have attracted a large amount of research interest as they facilitate direct observation of biointerfacial reactions. Thus far, attempts to achieve transparent hydroxyapatite have been focused on augmenting the sintering pressure and/or extending the sintering duration. This study aims at fabricating transparent HA using a direct and fast spark plasma sintering process with appropriate starting powder and moderate sintering pressure. Three types of raw powder, namely micro-spheres, nano-rods and nano-spheres, were sintered to investigate the optical and biological properties of the compacted pellets. It was found that in terms of transparency, the micro-sphere pellet sintered at 1000°C stood out with an in-line transmittance as high as 84% achieved at 1300nm for a 2mm thick sample. In addition, pellets fabricated from micro-spheres demonstrated the highest cell viability in in vitro biological tests with L929 cells. Living cells cultured on a transparent micro-sphere pellet could be directly and clearly observed by light microscopy. It is thus concluded that the micro-sphere powder is the most desirable raw material to manufacture transparent hydroxyapatite because it could enable dense pellets with notably high transparency and outstanding in vitro biocompatibility to be readily obtained.


Asunto(s)
Durapatita/farmacología , Ensayo de Materiales/métodos , Nanopartículas/química , Fenómenos Ópticos , Animales , Recuento de Células , Diferenciación Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Durapatita/química , Humanos , Ratones , Nanopartículas/ultraestructura , Imagen Óptica , Espectroscopía de Fotoelectrones , Dispersión de Radiación , Temperatura , Difracción de Rayos X
16.
Biomed Mater ; 11(6): 065006, 2016 10 27.
Artículo en Inglés | MEDLINE | ID: mdl-27786167

RESUMEN

It is challenging to obtain dense 45S5 Bioglass® (45S5) with controlled crystallinity and satisfactory mechanical properties by conventional sintering processes due to its fast crystallization above the first glass transition temperature. Spark plasma sintering (SPS) has stood out in this respect by virtue of its capability to provide fast heating and densification rates. However, there have been insufficient investigations into the in vitro biological properties of 45S5 compacts obtained by SPS. In this study, we report the fabrication of fully densified 45S5 pellets in the temperature range of 500 °C-600 °C through a rapid SPS process (sintering for 3 min) as well as the assessment of the influence of sintering temperature and aqueous aging on the biological properties of sintered pellets with L929 and MG63 cells. The cell culture results showed that both extended ageing and a lower SPS temperature in the 500-600 °C range could generally lead to faster cell proliferation and higher cell viability. The former was possibly caused by the slower alkalization of the media during cell culture, and the latter may have resulted from the release of more Ca and Si ions. The pellet sintered at 550 °C without aqueous aging led to the highest ALP activity in MG63 cells, which may be attributed to the high interfacial pH at the pellet surface and the leaching of more Si ions. Therefore, dense 45S5 compacts with mild crystallinity consolidated by SPS at 550 °C is a promising candidate for orthopedic implants in loading bearing applications.


Asunto(s)
Cerámica/química , Vidrio/química , Ensayo de Materiales , Propiedades de Superficie , Ingeniería de Tejidos/métodos , Envejecimiento , Animales , Materiales Biocompatibles/química , Calcio/química , Línea Celular , Proliferación Celular , Supervivencia Celular , Cristalización/métodos , Durapatita/química , Humanos , Concentración de Iones de Hidrógeno , Ratones , Ortopedia , Osteoblastos/metabolismo , Polvos , Silicio/química , Temperatura , Difracción de Rayos X
17.
ACS Appl Mater Interfaces ; 8(17): 10985-94, 2016 05 04.
Artículo en Inglés | MEDLINE | ID: mdl-27064825

RESUMEN

We report the first use of spark plasma sintering (SPS) as a single-step process to achieve superhydrophobic reduced graphene oxide (rGO). It was found that SPS was capable of converting smooth and electrically insulating graphene oxide (GO) sheets into highly electrically conductive rGO with minimum residual oxygen and hierarchical roughness which could be well retained after prolonged ultrasonication. At a temperature of 500 °C, which is lower than the conventional critical temperature for GO exfoliation, GO was successfully exfoliated, reduced, and hierarchically roughened. rGO fabricated by only 1 min of treatment at 1050 °C was superhydrophobic with a surface roughness (Ra) 10 times as large as that of GO as well as an extraordinarily high C:O ratio of 83.03 (atom %) and water contact angle of 153°. This demonstrates that SPS is a superior GO reduction technique, which enabled superhydrophobic rGO to be quickly and effectively achieved in one single step. Moreover, the superhydrophobic rGO fabricated by SPS showed an impressive bacterial antifouling and inactivation effect against Escherichia coli in both aqueous solution and the solid state. It is envisioned that the superhydrophobic rGO obtained in this study can be potentially used for a wide range of industrial and biomedical applications, such as the fabrication of self-cleaning and antibacterial surfaces.


Asunto(s)
Grafito/química , Antibacterianos , Óxidos , Temperatura , Agua
18.
Biofabrication ; 8(2): 025013, 2016 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-27213861

RESUMEN

Tissue engineering scaffolds for nerve regeneration, or artificial nerve conduits, are particularly challenging due to the high level of complexity the structure of the nerve presents. The list of requirements for artificial nerve conduits is long and includes the ability to physically guide nerve growth using physical and chemical cues as well as electrical stimulation. Combining these characteristics into a conduit, while maintaining biocompatibility and biodegradability, has not been satisfactorily achieved by currently employed fabrication techniques. Here we present a method combining pultrusion and wet-spinning techniques facilitating incorporation of pre-formed filaments into ionically crosslinkable hydrogels. This new biofabrication technique allows the incorporation of conducting or drug-laden filaments, controlled guidance channels and living cells into hydrogels, creating new improved conduit designs.


Asunto(s)
Hidrogeles/química , Neuronas/citología , Ingeniería de Tejidos/instrumentación , Andamios del Tejido/química , Alginatos/química , Animales , Materiales Biocompatibles/química , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Regeneración Nerviosa , Células PC12 , Ratas
19.
Acta Biomater ; 45: 328-339, 2016 11.
Artículo en Inglés | MEDLINE | ID: mdl-27554016

RESUMEN

Neuromuscular junctions (NMJ) are specialized synapses that link motor neurons with muscle fibers. These sites are fundamental to human muscle activity, controlling swallowing and breathing amongst many other vital functions. Study of this synapse formation is an essential area in neuroscience; the understanding of how neurons interact and control their targets during development and regeneration are fundamental questions. Existing data reveals that during initial stages of development neurons target and form synapses driven by biophysical and biochemical cues, and during later stages they require electrical activity to develop their functional interactions. The aim of this study was to investigate the effect of exogenous electrical stimulation (ES) electrodes directly in contact with cells, on the number and size of acetylcholine receptor (AChR) clusters available for NMJ formation. We used a novel in vitro model that utilizes a flexible electrical stimulation system and allows the systematic testing of several stimulation parameters simultaneously as well as the use of alternative electrode materials such as conductive polymers to deliver the stimulation. Functionality of NMJs under our co-culture conditions was demonstrated by monitoring changes in the responses of primary myoblasts to chemical stimulants that specifically target neuronal signaling. Our results suggest that biphasic electrical stimulation at 250Hz, 100µs pulse width and current density of 1mA/cm2 for 8h, applied via either gold-coated mylar or the conductive polymer PPy, significantly increased the number and size of AChRs clusters available for NMJ formation. This study supports the beneficial use of direct electrical stimulation as a strategic therapy for neuromuscular disorders. STATEMENT OF SIGNIFICANCE: The beneficial effects of electrical stimulation (ES) on human cells in vitro and in vivo have long been known. Although the effects of stimulation are clear and the therapeutic benefits are known, no uniform parameters exist with regard to the duration, frequency and amplitude of the ES. To this end, we are answering several important questions on the parameters for ES of nerve and muscle monocultures and co-cultures by probing the effects on the enhancement of acetylcholine receptors (AChR) clustering available for neuromuscular junction formation using a conductive platform. This work opens the possibility to combine electrical stimulus delivered via conductive polymer substrates, from which biomolecules could also be delivered, providing opportunities to further enhance the therapeutic effect.


Asunto(s)
Unión Neuromuscular/metabolismo , Receptores Colinérgicos/metabolismo , Animales , Calcio/metabolismo , Línea Celular , Técnicas de Cocultivo , Estimulación Eléctrica , Electrodos , Ensayo de Materiales , Ratones Endogámicos C57BL , Microscopía de Fuerza Atómica , Músculos/metabolismo , Tejido Nervioso/metabolismo
20.
Adv Mater ; 27(46): 7563-82, 2015 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-25914294

RESUMEN

The advent of implantable biomaterials has revolutionized medical treatment, allowing the development of the fields of tissue engineering and medical bionic devices (e.g., cochlea implants to restore hearing, vagus nerve stimulators to control Parkinson's disease, and cardiac pace makers). Similarly, future materials developments are likely to continue to drive development in treatment of disease and disability, or even enhancing human potential. The material requirements for implantable devices are stringent. In all cases they must be nontoxic and provide appropriate mechanical integrity for the application at hand. In the case of scaffolds for tissue regeneration, biodegradability in an appropriate time frame may be required, and for medical bionics electronic conductivity is essential. The emergence of graphene and graphene-family composites has resulted in materials and structures highly relevant to the expansion of the biomaterials inventory available for implantable medical devices. The rich chemistries available are able to ensure properties uncovered in the nanodomain are conveyed into the world of macroscopic devices. Here, the inherent properties of graphene, along with how graphene or structures containing it interface with living cells and the effect of electrical stimulation on nerves and cells, are reviewed.


Asunto(s)
Materiales Biocompatibles/química , Grafito/química , Estimulación Eléctrica , Humanos , Óxidos/química , Células Madre/citología , Ingeniería de Tejidos , Andamios del Tejido/química
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