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1.
Mater Sci Eng C Mater Biol Appl ; 62: 338-49, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26952432

RESUMO

The magnetic electrospun mats were lately established as an innovative biomaterial for hyperthermic cancer treatment. Unlike those surface-modified magnetic nanoparticles that may not firmly adhere onto the tumor for long-term duration, the magnetic mats with nanofibrous structure can promote cell adhesion and kill the tumor directly within an alternating magnetic field. However, most magnetic electrospun mats were fabricated using non-biodegradable polymers and organic solvents, causing the problems of removal after therapy and the suspected biotoxicity associated with residual solvent. Alginate (SA) was utilized in this investigation as the main material for electrospinning because of being biodegradable and water-soluble. The alginate-based electrospun mats were then treated by an ionic or a covalent crosslinking method, and then followed by chelation with Fe(2+)/Fe(3+) for chemical coprecipitation of Fe3O4 magnetic nanoparticles. Significant less cytotoxicity was noted on both liquid extracts from the ionic-crosslinked (Fe3O4-SA/PEO) and covalent-crosslinked (Fe3O4-SA/PVA) magnetic electrospun mats as well as the surface of Fe3O4-SA/PVA. In vitro hyperthermia assay indicated that the covalent-crosslinked magnetic alginate-based mats reduced tumor cell viability greater than Fe3O4 nanoparticles. Such magnetic electrospun mats are of potential for hyperthermia treatment by endoscopic/surgical delivery as well as serving as a supplementary debridement treatment after surgical tumor removal.


Assuntos
Alginatos/química , Hipertermia Induzida , Nanopartículas de Magnetita/química , Teste de Materiais , Animais , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Camundongos , Células NIH 3T3
2.
IEEE Trans Biomed Circuits Syst ; 8(2): 165-76, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24860041

RESUMO

Brain activity associated with attention sustained on the task of safe driving has received considerable attention recently in many neurophysiological studies. Those investigations have also accurately estimated shifts in drivers' levels of arousal, fatigue, and vigilance, as evidenced by variations in their task performance, by evaluating electroencephalographic (EEG) changes. However, monitoring the neurophysiological activities of automobile drivers poses a major measurement challenge when using a laboratory-oriented biosensor technology. This work presents a novel dry EEG sensor based mobile wireless EEG system (referred to herein as Mindo) to monitor in real time a driver's vigilance status in order to link the fluctuation of driving performance with changes in brain activities. The proposed Mindo system incorporates the use of a wireless and wearable EEG device to record EEG signals from hairy regions of the driver conveniently. Additionally, the proposed system can process EEG recordings and translate them into the vigilance level. The study compares the system performance between different regression models. Moreover, the proposed system is implemented using JAVA programming language as a mobile application for online analysis. A case study involving 15 study participants assigned a 90 min sustained-attention driving task in an immersive virtual driving environment demonstrates the reliability of the proposed system. Consistent with previous studies, power spectral analysis results confirm that the EEG activities correlate well with the variations in vigilance. Furthermore, the proposed system demonstrated the feasibility of predicting the driver's vigilance in real time.


Assuntos
Condução de Veículo , Eletroencefalografia/instrumentação , Tecnologia sem Fio/instrumentação , Atenção/fisiologia , Interfaces Cérebro-Computador , Vestuário , Eletroencefalografia/métodos , Humanos , Processamento de Sinais Assistido por Computador , Fases do Sono
3.
Anal Chim Acta ; 792: 101-9, 2013 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-23910974

RESUMO

A colloidal suspension of nanostructured poly(N-butyl benzimidazole)-graphene sheets (PBBIns-Gs) was used to modify a gold electrode to form a three-dimensional PBBIns-Gs/Au electrode that was sensitive to hydrogen peroxide (H2O2) in the presence of acetic acid (AcOH). The positively charged nanostructured poly(N-butyl benzimidazole) (PBBIns) separated the graphene sheets (Gs) and kept them suspended in an aqueous solution. Additionally, graphene sheets (Gs) formed "diaphragms" that intercalated Gs, which separated PBBIns to prevent tight packing and enhanced the surface area. The PBBIns-Gs/Au electrode exhibited superior sensitivity toward H2O2 relative to the PBBIns-modified Au (PBBIns/Au) electrode. Furthermore, a high yield of glucose oxidase (GOD) on the PBBIns-Gs of 52.3mg GOD per 1mg PBBIns-Gs was obtained from the electrostatic attraction between the positively charged PBBIns-Gs and negatively charged GOD. The non-destructive immobilization of GOD on the surface of the PBBIns-Gs (GOD-PBBIns-Gs) retained 91.5% and 39.2% of bioactivity, respectively, relative to free GOD for the colloidal suspension of the GOD-PBBIns-Gs and its modified Au (GOD-PBBIns-Gs/Au) electrode. Based on advantages including a negative working potential, high sensitivity toward H2O2, and non-destructive immobilization, the proposed glucose biosensor based on an GOD-PBBIns-Gs/Au electrode exhibited a fast response time (5.6s), broad detection range (10µM to 10mM), high sensitivity (143.5µAmM(-1)cm(-2)) and selectivity, and excellent stability. Finally, a choline biosensor was developed by dipping a PBBIns-Gs/Au electrode into a choline oxidase (ChOx) solution for enzyme loading. The choline biosensor had a linear range of 0.1µM to 0.83mM, sensitivity of 494.9µAmM(-1)cm(-2), and detection limit of 0.02µM. The results of glucose and choline measurement indicate that the PBBIns-Gs/Au electrode provides a useful platform for the development of oxidase-based biosensors.


Assuntos
Benzimidazóis/química , Técnicas de Química Analítica/métodos , Colina/análise , Coloides/química , Glucose/análise , Grafite/química , Nanoestruturas/química , Peroxidase/química , Eletrodos , Estrutura Molecular , Tamanho da Partícula , Polímeros/química , Reprodutibilidade dos Testes
4.
Biosens Bioelectron ; 46: 84-90, 2013 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-23517822

RESUMO

To break through the long time and complex procedures for the preparation of highly conjugated reduced graphene oxide (r-GO) in developing electrochemical sensor, a time-saving and simple method is investigated in this study. One novel step of the exfoliated accompanying carboxylated graphene sheet from pristine is achieved via Friedel-Crafts acylation. By electrophilic aromatic substitution, the succinic anhydride ring is opened and attaches covalently to the graphene sheet (Gs) to form exfoliated graphene with grafted 1-one-butyric acid (Gs-BA). The grafting chain converts anions in aqueous solution to maintain Gs-BA in a stable dispersion and noticeably decreases the π-π stacking of the exfoliated Gs during the drying process. The analytical results of the absorption spectroscopy demonstrate that the conjugation of Gs-BA is not significantly destroyed by this chemical modification; Gs-BA retains the Gs electrical properties favorable for developing electrochemical sensors. When polyamic acid-benzoxazole (PAA-BO), a hydrogen peroxide (H2O2)-sensitive probe, hybridizes with Gs-BA to form Gs-BA-PAA-BO, the electron transfer rate relating to the response time improves markedly from 1.09 s(-1) to 38.8 s(-1). Additionally, it offers a high performance for H2O2 sensing in terms of sensitivity and response time, making this method applicable for developing glucose and choline biosensors.


Assuntos
Derivados de Benzeno/química , Benzoxazóis/química , Ácido Butírico/química , Técnicas Eletroquímicas/métodos , Grafite/química , Peróxido de Hidrogênio/análise , Polímeros/química , Técnicas Biossensoriais/métodos , Catálise , Colina/análise , Eletrodos , Transporte de Elétrons , Elétrons , Glucose/análise , Ouro/química , Sensibilidade e Especificidade
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