Diffusion dynamics of small molecules from mesoporous silicon films by real-time optical interferometry

Mares, Jeremy W.; Weiss, Sharon M.

doi:10.1364/ao.50.005329

Cited by 11 publications

(8 citation statements)

References 35 publications

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“…The transport of large molecules within porous materials is slower than in bulk solution due to hindered diffusion in nanoscale pores. As a result, molecular diffusivities in nanopores depend not only on the nature of the molecules themselves but also on the geometry and morphology of the porous materials [ 53 , 54 ]. The equilibrium times for porous sensors having closed-ended pores in the flow-over scheme and open-ended pores in the flow-through scheme was investigated for analytes with different diffusivities and adsorption kinetics.…”

Section: Resultsmentioning

confidence: 99%

Comparative Kinetic Analysis of Closed-Ended and Open-Ended Porous Sensors

et al. 2016

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Efficient mass transport through porous networks is essential for achieving rapid response times in sensing applications utilizing porous materials. In this work, we show that open-ended porous membranes can overcome diffusion challenges experienced by closed-ended porous materials in a microfluidic environment. A theoretical model including both transport and reaction kinetics is employed to study the influence of flow velocity, bulk analyte concentration, analyte diffusivity, and adsorption rate on the performance of open-ended and closed-ended porous sensors integrated with flow cells. The analysis shows that open-ended pores enable analyte flow through the pores and greatly reduce the response time and analyte consumption for detecting large molecules with slow diffusivities compared with closed-ended pores for which analytes largely flow over the pores. Experimental confirmation of the results was carried out with open- and closed-ended porous silicon (PSi) microcavities fabricated in flow-through and flow-over sensor configurations, respectively. The adsorption behavior of small analytes onto the inner surfaces of closed-ended and open-ended PSi membrane microcavities was similar. However, for large analytes, PSi membranes in a flow-through scheme showed significant improvement in response times due to more efficient convective transport of analytes. The experimental results and theoretical analysis provide quantitative estimates of the benefits offered by open-ended porous membranes for different analyte systems.

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Section: Resultsmentioning

confidence: 99%

Comparative Kinetic Analysis of Closed-Ended and Open-Ended Porous Sensors

et al. 2016

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“…Accordingly, different salt water solutions are placed on PSi rings of 10 μm and 25 μm radius to determine their bulk sensitivity. The diffusion of the NaCl solution into the pores is nearly instantaneous due to the small size of NaCl [19,20]. Transmission measurements are conducted immediately after the 7.5 μL aliquot is placed on each ring.…”

Section: Bulk Sensitivity Measurementsmentioning

confidence: 99%

Porous silicon ring resonator for compact, high sensitivity biosensing applications

Rodriguez¹,

Hu²,

Weiss³

2015

Opt. Express

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A ring resonator is patterned on a porous silicon slab waveguide to produce a compact, high quality factor biosensor with a large internal surface area available for enhanced recognition of biological and chemical molecules. The porous nature of the ring resonator allows molecules to directly interact with the guided mode. Quality factors near 10,000 were measured for porous silicon ring resonators with a radius of 25 μm. A bulk detection sensitivity of 380 nm/RIU was measured upon exposure to salt water solutions. Specific detection of nucleic acid molecules was demonstrated with a surface detection sensitivity of 4 pm/nM.

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“… 44 , 47 − 50 The structural properties of the porous nanostructure, such as the pore diameter and porous layer thickness, have also a tremendous effect, as the deviation from the bulk diffusion coefficient is more pronounced for smaller pores and a thicker layer. 51 The motion of the diffusing molecule is also highly dependent on structural defects, as revealed by single-molecule diffusion analysis in mesoporous silica. 52 , 53 Molecule transport and adsorption in porous materials have been investigated, and models describing the hindered diffusion effect have been empirically derived.…”

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confidence: 99%

Mass Transfer Limitations of Porous Silicon-Based Biosensors for Protein Detection

et al. 2020

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Porous silicon (PSi) thin films have been widely studied for biosensing applications, enabling label-free optical detection of numerous targets. The large surface area of these biosensors has been commonly recognized as one of the main advantages of the PSi nanostructure. However, in practice, without application of signal amplification strategies, PSi-based biosensors suffer from limited sensitivity, compared to planar counterparts. Using a theoretical model, which describes the complex mass transport phenomena and reaction kinetics in these porous nanomaterials, we reveal that the interrelated effect of bulk and hindered diffusion is the main limiting factor of PSi-based biosensors. Thus, without significantly accelerating the mass transport to and within the nanostructure, the target capture performance of these biosensors would be comparable, regardless of the nature of the capture probe–target pair. We use our model to investigate the effect of various structural and biosensor characteristics on the capture performance of such biosensors and suggest rules of thumb for their optimization.

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Diffusion dynamics of small molecules from mesoporous silicon films by real-time optical interferometry

Cited by 11 publications

References 35 publications

Comparative Kinetic Analysis of Closed-Ended and Open-Ended Porous Sensors

Comparative Kinetic Analysis of Closed-Ended and Open-Ended Porous Sensors

Porous silicon ring resonator for compact, high sensitivity biosensing applications

Mass Transfer Limitations of Porous Silicon-Based Biosensors for Protein Detection

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