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1.
Carbohydr Polym ; 240: 116164, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32475540

RESUMO

Chitosan is suggested as no or low toxicity and biocompatible biomaterial. Digestion of chitosan to reduce molecular weight and formulate nanoparticle was generally used to improve efficiency for DNA or protein delivery. However, the toxicity of low-molecular-weight chitosan (LMWCS) towards freshwater fishes has not been well evaluated. Here, we reported the toxic mechanism of LMWCS using zebrafish (Danio rerio) liver (ZFL) cell line, zebrafish larvae, and adult fish. LMWCS rapidly induced cytotoxicity of ZFL cells and death of zebrafish. Cell membrane damaged by LMWCS reduced cell viability. Damaged membrane of epithelial cell in zebrafish larvae induced breakage of the yolk. Adult fish exhibited hypoxia before death due to multiple damages induced by LMWCS. Although the toxicity of LMWCS was revealed in zebrafish model, the toxicity was only present in pH < 7 and easy be neutralized by other negative ions. Collectively, these data improved a new understanding of LMWCS properties.


Assuntos
Materiais Biocompatíveis/toxicidade , Quitosana/toxicidade , Larva/efeitos dos fármacos , Fígado/efeitos dos fármacos , Peixe-Zebra/metabolismo , Animais , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Quitosana/análogos & derivados , Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Peso Molecular , Testes de Toxicidade
2.
Sci Rep ; 10(1): 6777, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-32303691

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

3.
Nanoscale Res Lett ; 14(1): 276, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31414236

RESUMO

We have studied the characteristics of frequency response at 850-nm GaAs high-speed vertical-cavity surface-emitting lasers (VCSELs) with different kinds of oxide aperture sizes and cavity length using the PICS3D simulation program. Using 5-µm oxide aperture sizes, the frequency response behavior can be improved from 18.4 GHz and 15.5 GHz to 21.2 GHz and 19 GHz in a maximum of 3 dB at 25 °C and 85 °C, respectively. Numerical simulation results also suggest that the frequency response performances improved from 21.2 GHz and 19 GHz to 30.5 GHz and 24.5 GHz in a maximum of 3 dB at 25 °C and 85 °C due to the reduction of cavity length from 3λ/2 to λ/2. Consequently, the high-speed VCSEL devices were fabricated on a modified structure and exhibited 50-Gb/s data rate at 85 °C.

4.
Sci Rep ; 7(1): 7185, 2017 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-28775264

RESUMO

Magnesium oxide (MgO) sensing membranes in pH-sensitive electrolyte-insulator-semiconductor structures were fabricated on silicon substrate. To optimize the sensing capability of the membrane, CF4 plasma was incorporated to improve the material quality of MgO films. Multiple material analyses including FESEM, XRD, AFM, and SIMS indicate that plasma treatment might enhance the crystallization and increase the grain size. Therefore, the sensing behaviors in terms of sensitivity, linearity, hysteresis effects, and drift rates might be improved. MgO-based EIS membranes with CF4 plasma treatment show promise for future industrial biosensing applications.

5.
Biomed Microdevices ; 17(3): 9954, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25926017

RESUMO

We developed a simple method to achieve semiquantitative detection of an amphiphilic biosample through measuring the length of flow on a microfluidic analytical device (µPAD) based on paper. When an amphiphilic sample was dripped into a straight microchannel defined with a printed wax barrier (hydrophobic) on filter paper (hydrophilic), the length of flow was affected by the reciprocal effect between the sample, the filter-paper channel and the wax barrier. The flow length decreased with increasing concentration of an amphiphilic sample because of adsorption of the sample on the hydrophobic barrier. Measurement of the flow length enabled a determination of the concentration of the amphiphilic sample. The several tested samples included surfactants (Tween 20 and Triton X-100), oligonucleotides (DNA), bovine serum albumin (BSA), human albumin, nitrite, glucose and low-density lipoprotein (LDL). The results show that the measurement of the flow length determined directly the concentration of an amphiphilic sample, whereas a non-amphiphilic sample was not amenable to this method. The proposed method features the advantages of small cost, simplicity, convenience, directness, rapidity (<5 min) and requirement of only a small volume (5 µL) of sample, with prospective applications in developing areas and sites near patients for testing at a point of care (POCT).


Assuntos
Biopolímeros/análise , Dispositivos Lab-On-A-Chip , Papel , Fitas Reagentes , Tensoativos/análise , Adsorção , Biopolímeros/química , Difusão , Desenho de Equipamento , Análise de Falha de Equipamento , Filtração/instrumentação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Tensoativos/química
6.
Biosens Bioelectron ; 50: 8-13, 2013 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-23827371

RESUMO

A novel aggregation-based biosensing method to achieve detection of oligonucleotides in a pinched-flow fractionation (PFF) microseparator was developed. Employing functionalized polystyrene microspheres, this method is capable of the direct detection of the concentration of a specific DNA sequence. The label-free target DNA hybridizes with probe DNA of two kinds on the surface of the microspheres and causes the formation of an aggregate, thus increasing the average size of the aggregate particles. On introducing the sample into a PFF microseparator, the aggregate particles locate at a specific position depending on the size of the aggregate. Through a multi-outlet asymmetric PFF microseparator, the aggregate particles become separated according to outlets. Because the size of the aggregate particles is proportional to the concentration of the target DNA, a rapid quantitative analysis is achievable with an optical microscope. A biological dose-response curve with concentration in a dynamic range 0.33-10nM has been achieved; the limit of detection is between 33 and 330 pM. The specificity of the method and the potential to detect single-nucleotide polymorphism (SNP) of known concentration were examined. The method features simple, direct and cheap detection, with a prospect of detecting other biochemical samples with distinct aggregation behavior, such as heavy-metal ions, bacteria and proteins.


Assuntos
Técnicas Biossensoriais/instrumentação , Fracionamento Químico/instrumentação , DNA/análise , DNA/genética , Polimorfismo de Nucleotídeo Único , Sequência de Bases , Microesferas , Poliestirenos/química , Sensibilidade e Especificidade
7.
Acta Biomater ; 9(5): 6606-15, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23376237

RESUMO

Nerve regeneration remains a difficult challenge due to the lack of safe and efficient matrix support. We designed a laminin (LN)-modified chitosan multi-walled nerve conduit combined with bone marrow stem cell (BMSC) grating to bridge a 10 mm long gap in the sciatic nerve of Sprague-Dawley rats. The repair outcome was monitored during 16 weeks after surgery. Successful grafting of LN onto the chitosan film, confirmed by immunolocalization, significantly improved cell adhesion. In vivo study showed that newly formed nerve cells covered the interior of the conduit to connect the nerve gap successfully in all groups. The rats implanted with the conduit combined with BMSCs showed the best results, in terms of nerve regrowth, muscle mass of gastrocnemius, function recovery and tract tracing. Neuroanatomical horseradish peroxidase tracer analysis of motor neurons in the lumbar spinal cord indicated that the amount and signal intensity were significantly improved. Furthermore, BMSCs suppressed neuronal cell death and promoted regeneration by suppressing the inflammatory and fibrotic response induced by chitosan after long-term implantation. In summary, this study suggests that LN-modified chitosan multi-walled nerve conduit combined with BMSCs is an efficient and safe conduit matrix for nerve regeneration.


Assuntos
Quitosana/administração & dosagem , Laminina/administração & dosagem , Regeneração Nervosa , Transplante de Células-Tronco , Animais , Feminino , Masculino , Células PC12 , Ratos , Ratos Sprague-Dawley , Engenharia Tecidual
8.
Org Lett ; 14(13): 3442-5, 2012 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-22697378

RESUMO

We have used a simple molecular recognition system to study substituent effects in aromatic interactions. A series of substituted benzoylleucine diethyl amides with aromatic rings of varying electronic character were crystallized. All of the substituted dimers organized into homochiral dimers in the solid state but with pronounced differences in regard to the orientation of the aromatic rings with respect to each other. However, no homochiral dimerization was observed in the unsubstituted case.

9.
Lab Chip ; 12(5): 923-31, 2012 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-22240904

RESUMO

We propose a novel technique that allows oligonucleotides with specific end-modification within a plug in a plug-based microfluidic device to undergo a locally enhanced concentration at the rear of the plug as the plug moves downstream. DNA was enriched and detected in situ upon exploiting a combined effect underlain by an entropic force induced through fluid shear (i.e. a hydrodynamic-repellent effect) and the interfacial adsorption (aqueous/oil interface) attributed to affinity. Flow fields within a plug were visualized quantitatively using micro-particle image velocimetry (micro-PIV); the distribution of the fluid shear strain rate explains how the hydrodynamic-repellent effect engenders a dumbbell-like region with an increased concentration of DNA. The concentration of FAM (6-carboxy-fluorescein)-labeled DNA (FC-DNA) and of TAMRA (tetramethyl-6-carboxyrhodamine)-labeled DNA (TC-DNA), respectively, and the hybridization of probe DNA (modified with FAM) with target DNA (modified with TAMRA) were investigated in devices; a confocal fluorescence microscope (CFM) was utilized to monitor the processes and to resolve the corresponding 2D patterns and 3D reconstruction of the DNA distribution in a plug. TC-DNA, but not FC-DNA, concentrating within a plug was affected by the combined effect so as to achieve a concentration factor (C(r)) twice that of FC-DNA because of the lipophilicity of TAMRA. Using fluorescence resonance-energy transfer (FRET), we characterized the hybridization of the DNA in a plug; the detection limit of a system, improved by virtue of the proposed technique (the locally enhanced concentration), for DNA detection was estimated to be 20-50 nM. This technique enables DNA to concentrate locally in a nL-pL free-solution plug, the locally enhanced concentration to profit the hybridization efficiency and the detection of DNA, prospectively serving as a versatile means to accomplish a rapid DNA detection in a small volume for a Lab-on-a-Chip (LOC) system.


Assuntos
Técnicas Analíticas Microfluídicas , Oligonucleotídeos/química , Animais , Humanos , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos
10.
Biomicrofluidics ; 5: 14111, 2011 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-21503162

RESUMO

For the diagnosis of biochemical reactions, the investigation of microflow behavior, and the confirmation of simulation results in microfluidics, experimentally quantitative measurements are indispensable. To characterize the mixing and reaction of fluids in microchannel devices, we propose a mixing quality index (M(qi)) to quantify the cross-sectional patterns (also called mixing patterns) of fluids, captured with a confocal-fluorescence microscope (CFM). The operating parameters of the CFM for quantification were carefully tested. We analyzed mixing patterns, flow advection, and mass exchange of fluids in the devices with overlapping channels of two kinds. The mixing length of the two devices derived from the analysis of M(qi) is demonstrated to be more precise than that estimated with a commonly applied method of blending dye liquors. By means of fluorescence resonance-energy transfer (FRET), we monitored the hybridization of two complementary oligonucleotides (a FRET pair) in the devices. The captured patterns reveal that hybridization is a progressive process along the downstream channel. The FRET reaction and the hybridization period were characterized through quantification of the reaction patterns. This analytical approach is a promising diagnostic tool that is applicable to the real-time analysis of biochemical and chemical reactions such as polymerase chain reaction (PCR), catalytic, or synthetic processes in microfluidic devices.

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