Size-selective immunofluorescence of Mycobacterium tuberculosis cells by capillary- and viscous forces

Yeo, Woon‐Hong; Chou, Fong Li; Fotouhi, Gareth; Oh, Kieseok; Stevens, Blake T.; Tseng, Hsiu Yang; Gao, Dayong; Shen, Amy Q.; Chung, Jae Hyun; Lee, Kyong Hoon

doi:10.1039/c0lc00077a

Cited by 15 publications

(10 citation statements)

References 7 publications

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“…A nanostructured tip is advantageous for electrical detection because the capacitance due to an electrical double layer can be minimized by the confined geometry. [13][14][15][16][17][18][19] To reduce the capacitance with electric insulation, the nanotip area except for the terminal end has been sealed with polymeror other dielectric layers. 1,19 However, insulated nanotips have proved challenging for fabrication in a reproducible fashion.…”

Section: Introductionmentioning

confidence: 99%

Electrolyte-free amperometric immunosensor using a dendritic nanotip

et al. 2013

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Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. Sensors composed of nanotips or nanodots have been described for highly sensitive amperometry enabled by confined geometry. However, both fabrication and use of nanostructured sensors remain challenging. This paper describes a dendritic nanotip used as an amperometric biosensor for highly sensitive detection of target bacteria. A dendritic nanotip is structured by Si nanowires coated with single-walled carbon nanotubes (SWCNTs) for generation of a high electric field. For reliable measurement using the dendritic structure, Si nanowires were uniformly fabricated by ultraviolet (UV) lithography and etching. The dendritic structure effectively increased the electric current density near the terminal end of the nanotip according to numerical computation. The electrical characteristics of a dendritic nanotip with additional protein layers was studied by cyclic voltammetry and I–V measurement in deionized (DI) water. When the target bacteria dielectrophoretically captured onto a nanotip were bound with fluorescence antibodies, the electric current through DI water decreased. Measurement results were consistent with fluorescence- and electron microscopy. The sensitivity of the amperometry was 10 cfu/sample volume (103 cfu/mL), which was equivalent to the more laborious fluorescence measurement method. The simple configuration of a dendritic nanotip can potentially offer an electrolyte-free detection platform for sensitive and rapid biosensors.

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Section: Introductionmentioning

confidence: 99%

Electrolyte-free amperometric immunosensor using a dendritic nanotip

et al. 2013

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“…In our previous work, microtip or nanotip sensors were used to concentrate target bacteria and DNA by using an alternating current (AC) electric field. [8][9][10] However, the approach was not specific to target analytes and the small sample volume (<10 mL) limited sensitivity. This paper describes a microtip-based immunosensor that overcomes these limitations.…”

Section: Introductionmentioning

confidence: 99%

Immunosensor towards low-cost, rapid diagnosis of tuberculosis

et al. 2012

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A rapid, accurate tuberculosis diagnostic tool that is compatible with the needs of tuberculosis-endemic settings is a long-sought goal. An immunofluorescence microtip sensor is described that detects Mycobacterium tuberculosis complex cells in sputum in 25 minutes. Concentration mechanisms based on flow circulation and electric field are combined at different scales to concentrate target bacteria in 1 mL samples onto the surfaces of microscale tips. Specificity is conferred by genus-specific antibodies on the microtip surface. Immunofluorescence is then used to detect the captured cells on the microtip. The detection limit in sputum is 200 CFU mL(-1) with a success rate of 96%, which is comparable to PCR.

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“…However, the value is maybe sufficient for a biosensor designed to detect large molecules with micron-size (2∼4 μm) such as those used to diagnose Mycobacterium tuberculosis (MTB) cells in blood serum [18]. …”

Section: Resultsmentioning

confidence: 99%

Organic Plasmon-Emitting Diodes for Detecting Refractive Index Variation

Chiu¹,

Cheng²,

Huang³

2013

Sensors

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A photo-excited organic layer on a metal thin film with a corrugated substrate was used to generate surface plasmon grating coupled emissions (SPGCEs). Directional emissions corresponded to the resonant condition of surface plasmon modes on the Au/air interface. In experimental comparisons of the effects of different pitch sizes on the plasmonic band-gap, the obtained SPGCEs were highly directional, with intensity increases as large as 10.38-fold. The FWHM emission spectrum was less than 70 nm. This method is easily applicable to detecting refractive index changes by using SP-coupled fluorophores in which wavelength emissions vary by viewing angle. The measurements and calculations in this study confirmed that the color wavelength of the SPGCE changed from 545.3 nm to 615.4 nm at certain viewing angles, while the concentration of contacting glucose increased from 10 to 40 wt%, which corresponded to a refractive index increase from 1.3484 to 1.3968. The organic plasmon-emitting diode exhibits a wider linearity range and a resolution of the experimental is 1.056 × 10−3 RIU. The sensitivity of the detection limit for naked eye of the experimental is 0.6 wt%. At a certain viewing angle, a large spectral shift is clearly distinguishable by the naked eye unaided by optoelectronic devices. These experimental results confirm the potential applications of the organic plasmon-emitting diodes in a low-cost, integrated, and disposable refractive-index sensor.

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Size-selective immunofluorescence of Mycobacterium tuberculosis cells by capillary- and viscous forces

Cited by 15 publications

References 7 publications

Electrolyte-free amperometric immunosensor using a dendritic nanotip

Electrolyte-free amperometric immunosensor using a dendritic nanotip

Immunosensor towards low-cost, rapid diagnosis of tuberculosis

Organic Plasmon-Emitting Diodes for Detecting Refractive Index Variation

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