Porous Silicon Photonic Crystals as Encoded Microcarriers

Meade, Shawn O.; Yoon, Myeong Sik; Ahn, Kyo Han; Sailor, Michael J.

doi:10.1002/adma.200400713

Cited by 85 publications

(94 citation statements)

References 19 publications

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“…The variation in refractive index resulting from the modulated etch produces sharp resonance features in the optical reflectivity spectrum of the film, whose wavelengths are determined by the characteristic frequency components of the modulated current waveform. 33 The film is then thermally hydrosilylated with 1-dodecene, following published procedures, 25,34 to generate a chemically stable hydrophobic layer. A second porous layer, to act as a host for magnetite nanoparticles, is etched into the substrate immediately beneath the encoding layer.…”

Section: Preparation and Characterization Of Magnetized Amphiphilic Pmentioning

confidence: 99%

Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals

et al. 2006

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This paper describes a method for local heating of discrete micro-liter scale liquid droplets. The droplets are covered with magnetic porous Si microparticles, and heating is achieved by application of an external alternating electromagnetic field. The magnetic porous Si microparticles consist of two layers: the top layer contains a photonic code and it is hydrophobic, with surfacegrafted dodecyl moieties. The bottom layer consists of a hydrophilic Si oxide host layer that is infused with Fe 3 O 4 nanoparticles. The amphiphilic microparticles spontaneously align at the interface of a water droplet immersed in mineral oil, allowing manipulation of the droplets by application of a magnetic field. Application of an oscillating magnetic field (338 kHz, 18A RMS current in a coil surrounding the experiment) generates heat in the superparamagnetic particles that can raise the temperature of the enclosed water droplet to >80 °C within 5 min.A simple microfluidics application is demonstrated: combining complementary DNA strands contained in separate droplets and then thermally inducing dehybridization of the conjugate. The complementary oligonucleotides were conjugated with the cyanine dye fluorophores Cy3 and Cy5 to quantify the melting/re-binding reaction by fluorescence resonance energy transfer (FRET). The magnetic porous Si microparticles were prepared as photonic crystals, containing spectral codes that allowed the identification of the droplets by reflectivity spectroscopy. The technique demonstrates the feasibility of tagging, manipulating, and heating small volumes of liquids without the use of conventional microfluidic channel and heating systems.

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Section: Preparation and Characterization Of Magnetized Amphiphilic Pmentioning

confidence: 99%

Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals

et al. 2006

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“…Because they can concentrate molecules within their nanostructure and protect them from the body's natural immunological responses, the particles can potentially carry a much higher dose than could be allowed with a free drug injection. The particles can also be manufactured with well-defined shapes and dimensions, allowing the reproducible loading and release of precise quantities [44][45][46].…”

Section: Particle Formulationsmentioning

confidence: 99%

“…The film can then be converted into microparticles by ultrasonic fracture. Conventional lithography [44,45] or microdroplet patterning [46,47] methods can also be used if particles with more uniform shapes are desired.…”

Section: Electrochemical Etchingmentioning

confidence: 99%

Porous silicon in drug delivery devices and materials☆

Anglin

Cheng

Freeman

et al. 2008

Advanced Drug Delivery Reviews

801

618

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Porous Si exhibits a number of properties that make it an attractive material for controlled drug delivery applications: The electrochemical synthesis allows construction of tailored pore sizes and volumes that are controllable from the scale of microns to nanometers; a number of convenient chemistries exist for the modification of porous Si surfaces that can be used to control the amount, identity, and in vivo release rate of drug payloads and the resorption rate of the porous host matrix; the material can be used as a template for organic and biopolymers, to prepare composites with a designed nanostructure; and finally, the optical properties of photonic structures prepared from this material provide a self-reporting feature that can be monitored in vivo. This paper reviews the preparation, chemistry, and properties of electrochemically prepared porous Si or SiO 2 hosts relevant to drug delivery applications.

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“…Depending on several parameters such as Si wafer dopant type and resistivity, current density, and electrolyte composition, a wie range of pore sizes and morphologies can be obtained. 14,15 In addition, the pore diameters can be systematically varied in either horizontal or vertical directions (relative to the wafer surface), leading to pore gradient 11-13 and multilayer [16][17][18] structures.…”

mentioning

confidence: 99%

Biosensing Using Porous Silicon Double-Layer Interferometers: Reflective Interferometric Fourier Transform Spectroscopy

et al. 2005

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A simple, chip-based implementation of a double-beam interferometer that can separate biomolecules based on size and that can compensate for changes in matrix composition is introduced. The interferometric biosensor uses a double-layer of porous Si comprised of a top layer with large pores and a bottom layer with smaller pores. The structure is shown to provide an on-chip reference channel analogous to a double-beam spectrometer, but where the reference and sample compartments are stacked one on top of the other. The reflectivity spectrum of this structure displays a complicated interference spectrum whose individual components can be resolved by fitting of the reflectivity data to a simple interference model or by fast Fourier transform (FFT). Shifts of the FFT peaks indicate biomolecule penetration into the different layers. The small molecule sucrose penetrates into both porous Si layers, whereas the large protein bovine serum albumin (BSA) only enters the large pores. BSA can be detected even in a large (100-fold by mass) excess of sucrose from the FFT spectrum. Detection can be accomplished either by computing the weighted difference in the frequencies of two peaks or by computing the ratio of the intensities of two peaks in the FFT spectrum.

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Porous Silicon Photonic Crystals as Encoded Microcarriers

Cited by 85 publications

References 19 publications

Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals

Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals

Porous silicon in drug delivery devices and materials☆

Biosensing Using Porous Silicon Double-Layer Interferometers: Reflective Interferometric Fourier Transform Spectroscopy

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