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1.
Adv Healthc Mater ; 9(1): e1901342, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31794161

RESUMO

Implanted pacemakers are usually bulky and rigid electronics that are constraint by limited battery lifetimes, and need to be installed and repaired via surgeries that risk secondary infection and injury. In this work, a flexible self-powered photoelectric cardiac stimulator is demonstrated based on hydrogenated amorphous Si (a-Si:H) radial p-i-n junctions (RJs), constructed upon standing Si nanowires grown directly on aluminum thin foils. The flexible RJ stimulators, with an open-circuit voltage of 0.67 V and short-circuit current density of 12.7 mA cm-2 under standard AM1.5G illumination, can be conformally attached to the uneven tissue surface to pace heart-beating under modulated 650 nm laser illumination. In vivo pacing evaluations on porcine hearts show that the heart rate can be effectively controlled by the external photoelectric stimulations, to increase from the normal rate of 101-128 beating min-1 . Importantly, the a-Si:H RJ units are highly biofriendly and biodegradable, with tunable lifetimes in phosphate-buffered saline environment controlled by surface coating and passivation, catering to the needs of short term or lasting cardiac pacing applications. This implantable a-Si:H RJ photoelectric stimulation strategy has the potential to establish eventually a self-powered, biocompatible, and conformable cardiac pacing technology for clinical therapy.

2.
Opt Express ; 27(26): 37248-37256, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31878508

RESUMO

Geometry and doping control in silicon nanowires (SiNWs) are both crucial aspects in fabricating three-dimensional (3D) radial junction thin film solar cells, while the coupling between them remains a peculiar aspect to be better understood. In this work, we focus on the geometry evolution and the doping effects realized in tin-catalyzed SiNWs grown via a plasma-enhanced vapor-liquid-solid procedure by using different diborane (B2H6) dopant flows. It is shown that with the increase of B2H6 flow rate from 0.3 to 2.1 SCCM, the radial growth of SiNWs is greatly accelerated by more than 30%, while the length is shortened to 50%. This can be related to the enhanced chemisorption probability of SiHx radicals, with the addition of B2H6, on the SiNW sidewall during silane (SiH4) plasma deposition in PECVD system, which leads to easier nucleation directly on the sidewalls and faster radial expansion of the SiNWs. A trade-off has to be sought between seeking a strong light trapping and ensuring a sufficient doping for high-quality PIN junction with the increase of B2H6 doping flow. These new understandings lay a critical basis for understanding and searching for an optimal growth control for constructing high-performance 3D radial junction thin-film solar cells.

3.
ACS Appl Mater Interfaces ; 11(28): 25457-25464, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31282143

RESUMO

A facile strategy is needed for accurate time-space supply of suitable growth factors or drugs. Polypyrrole (PPy) was able to carry almost all kinds of negatively charged biomolecules through anodizing method, which made it an appropriate way for codeposition of multiple molecules. The difference in the conjugation between different molecules and PPy makes it possible for selective release when the redox state of PPy changes. In this work, bovine serum albumin (BSA) and heparin (Hep) were chosen to be the model molecules in view of their differences in the level of electronegativity and molecular weight. Double-layer deposition method was used to improve the biocompatibility of PPy/BSA/Hep film. It was found the content of BSA and Hep in the film can be controlled by regulating deposition current and time. BSA release was facilitated under positive voltage and then promote the proliferation of preosteoblasts, while Hep release was promoted under negative voltage and enhance cell differentiation. Our work provides a dual-molecule model in PPy for selective release and further explores the mechanism of release selectivity, this discovery has potential applications in tissue engineering and regenerative medicine.


Assuntos
Adesão Celular , Condutividade Elétrica , Heparina/química , Membranas Artificiais , Osteoblastos/metabolismo , Polímeros/química , Pirróis/química , Soroalbumina Bovina/química , Animais , Bovinos , Linhagem Celular , Camundongos , Osteoblastos/citologia
4.
Colloids Surf B Biointerfaces ; 167: 213-219, 2018 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-29656204

RESUMO

Titanium and tantalum have been widely used for orthopedic and dental implant applications. However, how their inherent surface features regulate cellular osteogeneses still remains elusive. In this study, we engineered two distinct TiO2 and Ta2O5 nanorod films as the two model oxidized surfaces to investigate their intrinsic osteogenic behaviors. The results indicated that the distinctive gradient on zeta potential against pH, corresponding to the deprotonation rate, but not the hydroxyl amount or hydroxylation polarity played a critical role on the cellular osteogenic performance. TiO2 nanorod film with a higher deprotonation rate significantly upregulated the expression of osteogeneses-related gene and protein, comparing to that of Ta2O5 nanorod film. These results might be attributed to that surface with higher deprotonation rateprovided more Bronsted acid-base surface sites to react with protein residues, leading to a mild change in conformation of the absorbed proteins, and subsequently facilitating to trigger the integrin-focal adhesion cytoskeleton actin transduction pathway. This study, therefore, provides a new insight into the understanding the role of material surface hydroxylation on cellular osteogenic responses.


Assuntos
Nanotubos/química , Osteogênese/efeitos dos fármacos , Titânio/química , Células 3T3 , Animais , Células Cultivadas , Hidroxilação , Camundongos , Tamanho da Partícula , Propriedades de Superfície
5.
Sci Rep ; 7(1): 17926, 2017 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-29263335

RESUMO

In electrical stimulation (ES), daily stimulation time means the interacting duration with cells per day, and is a vital factor for mediating cellular function. In the present study, the effect of stimulation time on osteogenic differentiation of MC3T3-E1 cells was investigated under ES on polypyrrole (Ppy) planar interdigitated electrodes (IDE). The results demonstrated that only a suitable daily stimulation time supported to obviously upregulate the expression of ALP protein and osteogenesis-related genes (ALP, Col-I, Runx2 and OCN), while a short or long daily stimulation time showed no significant outcomes. These might be attributed to the mechanism that an ES induced transient change in intracellular calcium ion concentration, which was responsible for activating calcium ion signaling pathway to enhance cellular osteogenic differentiation. A shorter daily time could lead to insufficient duration for the transient change in intracellular calcium ion concentration, and a longer daily time could give rise to cellular fatigue with no transient change. This work therefore provides new insights into the fundamental understanding of cell responses to ES and will have an impact on further designing materials to mediate cell behaviors.


Assuntos
Diferenciação Celular , Estimulação Elétrica , Osteoblastos/citologia , Osteogênese , Polímeros/química , Pirróis/química , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Cálcio/metabolismo , Proliferação de Células , Células Cultivadas , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Eletrodos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Osteoblastos/metabolismo , Osteocalcina/genética , Osteocalcina/metabolismo , Crânio/citologia , Crânio/metabolismo
6.
J Inequal Appl ; 2017(1): 48, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28280292

RESUMO

In this paper, the authors study the boundedness of multilinear Calderón-Zygmund singular integral operators and their commutators in generalized Morrey spaces.

7.
Macromol Biosci ; 16(9): 1368-80, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27276339

RESUMO

Electrospun fibers of hydrophilic polymers meet challenges in a rapid degradation of fiber matrices and discharge of antibiotics to comply with requirements of infection control as a dermal regeneration template. In the current study, a pH conversion process is initially developed to ensure fluent electrospinning, an efficient in situ cross-linking of electrospun gelatin fibers with oxidized alginate and simultaneous loading of gentamicin sulfate (GS) and hydrophobic ciprofloxacin into fibers. The dual drug-loaded fibers indicate a complete release of GS during 6 d and a sustained release of ciprofloxacin for over three weeks, and the antibiotics release indicates significant growth inhibitions on Pseudomonas aeruginosa and Staphylococcus epidermidis. The wound healing efficacy is evaluated on a deep burn model infected with 10(8) CFU of P. aeruginosa. Compared with fibers with loaded individual drugs, the concomitant release of GS and ciprofloxacin significantly reduces the bacteria numbers in wound and livers, at around 2.30 × 10(5) and 1.25 × 10(3) CFU after 3 d, respectively. The wound re-epithelization, blood vessel formation, collagen deposition, and tissue remodeling process are accelerated with a complete healing observed after 21 d. This study provides a feasible strategy to design cross-linked hydrophilic fibers with an extended drug release for biomedical applications.


Assuntos
Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Queimaduras/tratamento farmacológico , Queimaduras/microbiologia , Derme/patologia , Gelatina/química , Regeneração/efeitos dos fármacos , Engenharia Tecidual/métodos , Alginatos/química , Animais , Queimaduras/patologia , Contagem de Colônia Microbiana , Reagentes para Ligações Cruzadas/química , Liberação Controlada de Fármacos , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Imuno-Histoquímica , Camundongos , Células NIH 3T3 , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus epidermidis/efeitos dos fármacos , Cicatrização/efeitos dos fármacos
8.
Mater Sci Eng C Mater Biol Appl ; 44: 44-51, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25280678

RESUMO

Inspired by the excellent adhesive property of mussel adhesive protein, we added polydopamine (PDA) to calcium phosphate cement (PDA-CPC) to enhance its compressive strength previously. The mineralization and mechanism on PDA-CPC were investigated by soaking it in simulated body fluid in this study. The results indicated that PDA promoted the conversion of dicalcium phosphate dihydrate and α-tricalcium phosphate to hydroxyapatite (HA) in the early stage but inhibited this conversion subsequently. PDA promoted the rapid mineralization on PDA-CPC to form a layer of nanoscale calcium phosphate (CaP) whereas there was no CaP formation on the control-CPC after 1d of soaking. This layer of nanoscale CaP was similar to that of natural bone, which was always observed during soaking. X-ray photoelectron spectroscopy showed that the peak of CO of PDA existed in the newly formed CaP on PDA-CPC, indicating the co-precipitation of CaP with PDA. Furthermore, the newly formed CaP on PDA-CPC was HA confirmed by transmission electron microscopy, which the newly formed HA was in association with PDA. Therefore, PDA increased the capacity of mineralization of CPC and induced the formation of nanoscale bone-like apatite on PDA-CPC. Thus, this provides the feasible route for surface modification on CPC.


Assuntos
Materiais Biomiméticos/química , Cimentos para Ossos/química , Fosfatos de Cálcio/química , Indóis/química , Polímeros/química , Animais , Bivalves , Cimentos para Ossos/síntese química , Fosfatos de Cálcio/síntese química , Força Compressiva , Durapatita/química , Indóis/síntese química , Microscopia Eletrônica de Transmissão , Nanoestruturas/química , Espectroscopia Fotoeletrônica , Polímeros/síntese química , Espectroscopia de Infravermelho com Transformada de Fourier , Raios X
9.
Huan Jing Ke Xue ; 35(2): 547-54, 2014 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-24812946

RESUMO

Antimony has been ubiquitously present in the aquatic environment as a toxic and rare metalloid element. The contamination of antimony and its compounds in the environment is increasingly severe, so it has been received extensive attention by the international scientific community. The cruise was carried out in the coastal area of Zhejiang and Fujian provinces in the East China Sea (ECS) in May 2008. The concentrations of total dissolved inorganic antimony (TDISb) were measured by Hydride Generation-Atomic Fluorescence (HG-AFS). The concentration ranges of TDISb in the surface and bottom layer were 0.68-5.64 nmol x L(-1) and 0.71-5.25 nmol x L(-1) with averages of 2.25 and 1.79 nmol x L(-1), respectively. The concentration of TDISb in the study area was lower than the environmental quality standards for surface water of China and drinking water standards of World Health Organization (about 41.08 nmol x L(-1)), indicating that it remained at the pristine level. The concentration of TDISb decreased gradually from the coastal area to the central ECS shelf with higher concentration in the surface layer than the bottom. Water mass mixing, adsorption/desorption behavior on the surface of the suspended particulate matters (SPM) and biological activities were the main influence factors of TDISb biogeochemistry in the study area.


Assuntos
Antimônio/análise , Monitoramento Ambiental , Poluentes Ambientais/análise , Adsorção , China , Poluentes Ambientais/normas
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