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1.
Nat Commun ; 12(1): 5008, 2021 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-34429436

RESUMO

Capabilities for continuous monitoring of pressures and temperatures at critical skin interfaces can help to guide care strategies that minimize the potential for pressure injuries in hospitalized patients or in individuals confined to the bed. This paper introduces a soft, skin-mountable class of sensor system for this purpose. The design includes a pressure-responsive element based on membrane deflection and a battery-free, wireless mode of operation capable of multi-site measurements at strategic locations across the body. Such devices yield continuous, simultaneous readings of pressure and temperature in a sequential readout scheme from a pair of primary antennas mounted under the bedding and connected to a wireless reader and a multiplexer located at the bedside. Experimental evaluation of the sensor and the complete system includes benchtop measurements and numerical simulations of the key features. Clinical trials involving two hemiplegic patients and a tetraplegic patient demonstrate the feasibility, functionality and long-term stability of this technology in operating hospital settings.


Assuntos
Técnicas Biossensoriais/métodos , Fontes de Energia Elétrica , Pressão , Temperatura , Tecnologia sem Fio , Adulto , Idoso , Idoso de 80 Anos ou mais , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Pele , Termografia/instrumentação , Termografia/métodos
2.
Nat Mater ; 2021 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-34326506

RESUMO

Flexible electronic/optoelectronic systems that can intimately integrate onto the surfaces of vital organ systems have the potential to offer revolutionary diagnostic and therapeutic capabilities relevant to a wide spectrum of diseases and disorders. The critical interfaces between such technologies and living tissues must provide soft mechanical coupling and efficient optical/electrical/chemical exchange. Here, we introduce a functional adhesive bioelectronic-tissue interface material, in the forms of mechanically compliant, electrically conductive, and optically transparent encapsulating coatings, interfacial layers or supporting matrices. These materials strongly bond both to the surfaces of the devices and to those of different internal organs, with stable adhesion for several days to months, in chemistries that can be tailored to bioresorb at controlled rates. Experimental demonstrations in live animal models include device applications that range from battery-free optoelectronic systems for deep-brain optogenetics and subdermal phototherapy to wireless millimetre-scale pacemakers and flexible multielectrode epicardial arrays. These advances have immediate applicability across nearly all types of bioelectronic/optoelectronic system currently used in animal model studies, and they also have the potential for future treatment of life-threatening diseases and disorders in humans.

3.
Nat Biotechnol ; 39(10): 1228-1238, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34183859

RESUMO

Temporary cardiac pacemakers used in periods of need during surgical recovery involve percutaneous leads and externalized hardware that carry risks of infection, constrain patient mobility and may damage the heart during lead removal. Here we report a leadless, battery-free, fully implantable cardiac pacemaker for postoperative control of cardiac rate and rhythm that undergoes complete dissolution and clearance by natural biological processes after a defined operating timeframe. We show that these devices provide effective pacing of hearts of various sizes in mouse, rat, rabbit, canine and human cardiac models, with tailored geometries and operation timescales, powered by wireless energy transfer. This approach overcomes key disadvantages of traditional temporary pacing devices and may serve as the basis for the next generation of postoperative temporary pacing technology.

4.
Materials (Basel) ; 14(7)2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33805202

RESUMO

This research work deals with the comparative study of C6F12O + Ar and CF4 + Ar gas chemistries in respect to Si and SiO2 reactive-ion etching processes in a low power regime. Despite uncertain applicability of C6F12O as the fluorine-containing etchant gas, it is interesting because of the liquid (at room temperature) nature and weaker environmental impact (lower global warming potential). The combination of several experimental techniques (double Langmuir probe, optical emission spectroscopy, X-ray photoelectron spectroscopy) allowed one (a) to compare performances of given gas systems in respect to the reactive-ion etching of Si and SiO2; and (b) to associate the features of corresponding etching kinetics with those for gas-phase plasma parameters. It was found that both gas systems exhibit (a) similar changes in ion energy flux and F atom flux with variations on input RF power and gas pressure; (b) quite close polymerization abilities; and (c) identical behaviors of Si and SiO2 etching rates, as determined by the neutral-flux-limited regime of ion-assisted chemical reaction. Principal features of C6F12O + Ar plasma are only lower absolute etching rates (mainly due to the lower density and flux of F atoms) as well as some limitations in SiO2/Si etching selectivity.

5.
Nat Commun ; 11(1): 5990, 2020 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-33239608

RESUMO

Bioresorbable electronic stimulators are of rapidly growing interest as unusual therapeutic platforms, i.e., bioelectronic medicines, for treating disease states, accelerating wound healing processes and eliminating infections. Here, we present advanced materials that support operation in these systems over clinically relevant timeframes, ultimately bioresorbing harmlessly to benign products without residues, to eliminate the need for surgical extraction. Our findings overcome key challenges of bioresorbable electronic devices by realizing lifetimes that match clinical needs. The devices exploit a bioresorbable dynamic covalent polymer that facilitates tight bonding to itself and other surfaces, as a soft, elastic substrate and encapsulation coating for wireless electronic components. We describe the underlying features and chemical design considerations for this polymer, and the biocompatibility of its constituent materials. In devices with optimized, wireless designs, these polymers enable stable, long-lived operation as distal stimulators in a rat model of peripheral nerve injuries, thereby demonstrating the potential of programmable long-term electrical stimulation for maintaining muscle receptivity and enhancing functional recovery.


Assuntos
Implantes Absorvíveis , Terapia por Estimulação Elétrica/instrumentação , Traumatismos dos Nervos Periféricos/terapia , Poliuretanos/química , Tecnologia sem Fio/instrumentação , Animais , Modelos Animais de Doenças , Terapia por Estimulação Elétrica/métodos , Feminino , Humanos , Teste de Materiais , Músculo Esquelético/inervação , Músculo Esquelético/fisiologia , Ratos , Regeneração , Nervo Isquiático/lesões , Nervo Isquiático/fisiologia
6.
Sci Adv ; 6(35): eabb1093, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32923633

RESUMO

Implantable drug release platforms that offer wirelessly programmable control over pharmacokinetics have potential in advanced treatment protocols for hormone imbalances, malignant cancers, diabetic conditions, and others. We present a system with this type of functionality in which the constituent materials undergo complete bioresorption to eliminate device load from the patient after completing the final stage of the release process. Here, bioresorbable polyanhydride reservoirs store drugs in defined reservoirs without leakage until wirelessly triggered valve structures open to allow release. These valves operate through an electrochemical mechanism of geometrically accelerated corrosion induced by passage of electrical current from a wireless, bioresorbable power-harvesting unit. Evaluations in cell cultures demonstrate the efficacy of this technology for the treatment of cancerous tissues by release of the drug doxorubicin. Complete in vivo studies of platforms with multiple, independently controlled release events in live-animal models illustrate capabilities for control of blood glucose levels by timed delivery of insulin.

7.
Sci Adv ; 6(24): eaay5065, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32577503

RESUMO

Dipole alignment in ferroelectric polymers is routinely exploited for applications in charge-based applications. Here, we present the first experimental realization of ideally ordered dipole alignment in α-phase nylon-11 nanowires. This is an unprecedented discovery as dipole alignment is typically only ever achieved in ferroelectric polymers using an applied electric field, whereas here, we achieve dipole alignment in as-fabricated nanowires of 'non-ferroelectric' α-phase nylon-11, an overlooked polymorph of nylon proposed 30 years ago but never practically realized. We show that the strong hydrogen bonding in α-phase nylon-11 serves to enhance the molecular ordering, resulting in exceptional intensity and thermal stability of surface potential. This discovery has profound implications for the field of triboelectric energy harvesting, as the presence of an enhanced surface potential leads to higher mechanical energy harvesting performance. Our approach therefore paves the way towards achieving robust, high-performance mechanical energy harvesters based on this unusual ordered phase of nylon-11.

8.
Chem Commun (Camb) ; 54(50): 6863-6866, 2018 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-29855641

RESUMO

Crystal structure is crucial in determining the properties of piezoelectric polymers, particularly at the nanoscale where precise control of the crystalline phase is possible. Here, we investigate the electromechanical properties of three distinct crystalline phases of Nylon-11 nanowires using advanced scanning probe microscopy techniques. Stiff α-phase nanowires exhibited a low piezoelectric response, while relatively soft δ'-phase nanowires displayed an enhanced piezoelectric response.

9.
Interface Focus ; 6(4): 20160026, 2016 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-27499846

RESUMO

Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer-metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units.

10.
Small ; 10(4): 653-9, 2014 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-24106040

RESUMO

Efficient room temperature NIR detection with sufficient current gain is made with a solution-processed networked SWNT FET. The high performance NIR-FET with significantly enhanced photocurrent by more than two orders of magnitude compared to dark current in the depleted state is attributed to multiple Schottky barriers in the network, each of which absorb NIR and effectively separate photocarriers to corresponding electrodes.

11.
J Lifestyle Med ; 3(1): 62-7, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26064839

RESUMO

BACKGROUND: Leptin, angiopoietin-related growth factor (AGF), adiponectin (ADP), and retinol-binding protein 4 (RBP4) are cytokines associated with the development of metabolic disorders, such as type 2 diabetes and cardio vascular disease. However, the levels of these cytokines have not extensively studied in non-diabetic subjects. Therefore, we analyzed the differences in these cytokine levels according to sex and age in non-diabetic Korean population. METHODS: Blood samples were collected from 59 non-diabetic Korean adults (male, 32; female, 27). The anthropometric and biochemical data were measured at the health examination center. Serum adipokines and hepatokines were measured by enzyme linked immunosorbent assay (ELISA). The data were analyzed according to sex and age-based quartiles. RESULTS: Serum leptin values were higher in females (8.60 ± 3 µg/ml) compared with males (2.99 ± 2.9 µg/ml). However, RBP4 was higher in males (84.05 ± 47.04 µg/ml) than in females (61.25 ± 45.42 µg/ml). The AGF and ADP values were not significantly different between males and females. RBP4 level was inversely correlated with age quartile in males, while leptin was significantly associated with body mass index and insulin resistance. CONCLUSION: RBP4 and AGF levels showed age-associated change, and leptin was consistently higher in females. Therefore, a large-scale analysis to determine the normal range of adipokines and hepatokines concentration in healthy Korean population is necessary. When interpreting adipokine and hepatokine levels, the difference in age and sex needs to be taken into account.

12.
Exp Mol Med ; 44(10): 578-85, 2012 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-22824914

RESUMO

Although peroxisome proliferator receptor (PPAR)-α and PPAR-γ agonist have been developed as chemical tools to uncover biological roles for the PPARs such as lipid and carbohydrate metabolism, PPAR-δ has not been fully investigated. In this study, we examined the effects of the PPAR-δ agonist GW0742 on fatty liver changes and inflammatory markers. We investigated the effects of PPAR-δ agonist GW0742 on fatty liver changes in OLETF rats. Intrahepatic triglyceride contents and expression of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and monocyte chemo-attractant protein-1 (MCP-1) and also, PPAR-γ coactivator (PGC)-1α gene were evaluated in liver tissues of OLETF rats and HepG2 cells after GW0742 treatment. The level of TNF-α and MCP-1 was also examined in supernatant of Raw264. 7 cell culture. To address the effects of GW0742 on insulin signaling, we performed in vitro study with AML12 mouse hepatocytes. Rats treated with GW0742 (10 mg/kg/day) from 26 to 36 weeks showed improvement in fatty infiltration of the liver. In liver tissues, mRNA expressions of TNF-α, MCP-1, and PGC-1α were significantly decreased in diabetic rats treated with GW0742 compared to diabetic control rats. We also observed that GW0742 had inhibitory effects on palmitic acid-induced fatty accumulation and inflammatory markers in HepG2 and Raw264.7 cells. The expression level of Akt and IRS-1 was significantly increased by treatment with GW0742. The PPAR-δ agonist may attenuate hepatic fat accumulation through anti-inflammatory mechanism, reducing hepatic PGC-1α gene expression, and improvement of insulin signaling.


Assuntos
Anti-Inflamatórios/farmacologia , Fígado Gorduroso/tratamento farmacológico , PPAR delta/agonistas , Tiazóis/farmacologia , Animais , Anti-Inflamatórios/uso terapêutico , Glicemia , Citocinas/genética , Citocinas/metabolismo , Diabetes Mellitus/sangue , Diabetes Mellitus/imunologia , Diabetes Mellitus/metabolismo , Fígado Gorduroso/sangue , Fígado Gorduroso/imunologia , Teste de Tolerância a Glucose , Células Hep G2 , Humanos , Resistência à Insulina , Fígado/metabolismo , Masculino , PPAR delta/metabolismo , Ratos , Ratos Long-Evans , Tiazóis/uso terapêutico , Triglicerídeos/metabolismo
13.
Adv Mater ; 24(33): 4540-6, 2012 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-22786699

RESUMO

High performance field-induced AC electroluminescence (EL) in a simple ITO/insulator/hybrid emitter/Au structure was demonstrated with efficient control of the brightness and colors based on solution-processed nanohybrids of CdSe-ZnS core-shell colloidal quantum dots and fluorescent polymers.


Assuntos
Condutividade Elétrica , Medições Luminescentes , Pontos Quânticos , Compostos de Cádmio/química , Coloides , Eletroquímica , Corantes Fluorescentes/química , Ouro/química , Polímeros/química , Compostos de Selênio/química , Sulfetos/química , Compostos de Zinco/química
14.
Lab Anim Res ; 27(3): 259-63, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21998617

RESUMO

Recently, loss of endogenous glutathione during N-methyl-D-aspartate (NMDA) receptor-mediated excitotoxic injury, and the resultant overproduction of reactive oxygen species (ROS) through an arachidonic acid cascade process in brain, have been implicated in neuronal damage in various neurodegenerative diseases. Glutathione depletion induced by L-buthionine-(S,R)-sulfoximine (BSO), an inhibitor of glutathione synthesis, is known to cause arachidonic acid-mediated excitotoxicity in primary mixed cortical cultures. The aim of this study was to investigate whether esculetin (6,7-dihydroxycoumarin), an inhibitor of lipoxygenase, protects against neurotoxicity induced by NMDA or BSO. We observed that neurotoxicity induced by NMDA but not kainic acid was attenuated by esculetin. At the same concentration (100 µM), esculetin attenuated the (45)Ca(2+) uptake elevation induced by NMDA. Free radical-mediated neuronal injury induced by H(2)O(2) and xanthine/xanthine oxidase was concentration-dependently blocked by esculetin. Esculetin (1-30 µM) dose-dependently inhibited BSO-induced neuronal injury. In addition, arachidonate-induced neurotoxicity was completely blocked by esculetin. BSO also reduced glutathione peroxidase (GPx) activity, but did not change glutathione reductase (GR) activity 24 h after treatment. Esculetin dose-dependently increased GR activity, but did not alter GPx activity. These findings suggest that esculetin can contribute to the rescue of neuronal cells from NMDA neurotoxicity and that this protective effect occurs partly through NMDA receptor modulation and the sparing of glutathione depletion.

15.
Nano Lett ; 11(3): 966-72, 2011 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-21280640

RESUMO

We developed a high-performance field-induced polymer electroluminescence (FPEL) device consisting of four stacked layers: a top metal electrode/thin solution-processed nanocomposite film of single wall carbon nanotubes (SWNTs) and a fluorescent polymer/insulator/transparent bottom electrode working under an alternating current (AC) electric field. A small amount of SWNTs that were highly dispersed in the fluorescent polymer matrix by a conjugate block copolymer dispersant significantly enhanced EL, and we were able to realize an SWNT-FPEL device with a light emission of approximately 350 cd/m(2) at an applied voltage of ±25 V and an AC frequency of 300 kHz. The brightness of the SWNT-FPEL device is much greater than those of other AC-based organic or even inorganic ELs that generally require at least a few hundred volts. Light is emitted from our SWNT-FPEL device because of the sequential injection of field-induced holes and then electron carriers through ambipolar carbon nanotubes under an AC field, followed by exciton formation in the conjugated organic layer. Field-induced bipolar charge injection provides great material design freedom for our devices; the energy level does not have to be aligned between the electrode and the emission layer, and the balance of the carrier injected and transported can be altered in contrast to that in conventional organic light-emitting diodes, leading to an extremely cost-effective and unified device architecture that is applicable to all red-green-blue fluorescent polymers.

16.
Biol Pharm Bull ; 27(5): 723-6, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15133254

RESUMO

Oxidative stress caused by an elevation in reactive oxygen species (ROS) plays an important role in Alzheimer's disease and other neurodegenerative diseases. In this study, we examined the neuroprotective effect of danthron (1,8-dihydroxyanthraquinone) against neurotoxicities induced by beta-amyloid (25-35), excitotoxins, apoptosis, and oxidative stress in primary cortical cultures. Danthron dose-dependently reduced neuronal injury induced by 30 microM beta-amyloid (25-35). Danthron significantly inhibited oxidative injury induced by 100 microM Fe(3+) and decreased membrane lipid peroxidation induced by 100 microM Fe(3+) as measured by thiobarbituric-acid-reactive substance (TBARS). Danthron (0.5-50 microM) ameliorated the effects of buthionine sulfoximine (BSO, 1 mM), which depletes endogenous glutathione by 10-73%. Danthron also dose-dependently inhibited neuronal injury mediated by nitric oxide (NO) radicals, but failed to inhibit injury due to superoxide radicals (O(2-)). These results suggest danthron treatment may, in part, reduce neurotoxicity related to beta-amyloid protein by both dominant inhibitory effects on membrane lipid peroxidation and glutathione deprivation.


Assuntos
Peptídeos beta-Amiloides/toxicidade , Antraquinonas/farmacologia , Córtex Cerebral/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Fragmentos de Peptídeos/toxicidade , Peptídeos beta-Amiloides/antagonistas & inibidores , Animais , Células Cultivadas , Córtex Cerebral/metabolismo , Relação Dose-Resposta a Droga , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/fisiologia , Camundongos , Camundongos Endogâmicos ICR , Estresse Oxidativo/fisiologia , Fragmentos de Peptídeos/antagonistas & inibidores
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