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DNA Optical Detection Based on Porous Silicon Technology: from Biosensors to Biochips

View Article: PubMed Central

ABSTRACT

A photochemical functionalization process which passivates the porous silicon surface of optical biosensors has been optimized as a function of the thickness and the porosity of the devices. The surface modification has been characterized by contact angle measurements. Fluorescence measurements have been used to investigate the stability of the DNA single strands bound to the nanostructured material. A dose-response curve for an optical label-free biosensor in the 6-80 mM range has been realized.

No MeSH data available.


A) Fluorescence of the chip surface after the binding of the labelled ssDNA; B) after the overnight dialysis in HEPES solution; C) after the overnight dialysis in deionised water.
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f3-sensors-07-00214: A) Fluorescence of the chip surface after the binding of the labelled ssDNA; B) after the overnight dialysis in HEPES solution; C) after the overnight dialysis in deionised water.

Mentions: To test the stability of the covalent bonding between the organic linker layers, which homogeneously cover the PSi surface, and the biological probes we have used a fluorescent DNA single strand as an optical tracer. After the chemical bonding of the labelled ssDNA, the chip was observed by the fluorescence macroscopy system. Under the light of the 100W high-pressure mercury source, we have found a high and homogeneous fluorescence on the whole chip surface which still remains bright even after two overnight dialysis washings in a HEPES solution and in deionised water, as it can be seen in Figures 3 A, B, and C. We have also studied the yield of the chemical functionalization by spotting different concentrations of the fluorescent ssDNA and measuring the fluorescence intensities of the images before and after the washings. The results reported in Figure 4 confirm the qualitative findings of Figure 3: the fluorescent intensities decrease but remain of the same order of magnitude. From this graph we can also estimate the concentration of the DNA probe which saturates the binding sites available.


DNA Optical Detection Based on Porous Silicon Technology: from Biosensors to Biochips
A) Fluorescence of the chip surface after the binding of the labelled ssDNA; B) after the overnight dialysis in HEPES solution; C) after the overnight dialysis in deionised water.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756702&req=5

f3-sensors-07-00214: A) Fluorescence of the chip surface after the binding of the labelled ssDNA; B) after the overnight dialysis in HEPES solution; C) after the overnight dialysis in deionised water.
Mentions: To test the stability of the covalent bonding between the organic linker layers, which homogeneously cover the PSi surface, and the biological probes we have used a fluorescent DNA single strand as an optical tracer. After the chemical bonding of the labelled ssDNA, the chip was observed by the fluorescence macroscopy system. Under the light of the 100W high-pressure mercury source, we have found a high and homogeneous fluorescence on the whole chip surface which still remains bright even after two overnight dialysis washings in a HEPES solution and in deionised water, as it can be seen in Figures 3 A, B, and C. We have also studied the yield of the chemical functionalization by spotting different concentrations of the fluorescent ssDNA and measuring the fluorescence intensities of the images before and after the washings. The results reported in Figure 4 confirm the qualitative findings of Figure 3: the fluorescent intensities decrease but remain of the same order of magnitude. From this graph we can also estimate the concentration of the DNA probe which saturates the binding sites available.

View Article: PubMed Central

ABSTRACT

A photochemical functionalization process which passivates the porous silicon surface of optical biosensors has been optimized as a function of the thickness and the porosity of the devices. The surface modification has been characterized by contact angle measurements. Fluorescence measurements have been used to investigate the stability of the DNA single strands bound to the nanostructured material. A dose-response curve for an optical label-free biosensor in the 6-80 mM range has been realized.

No MeSH data available.