Macro-/Nanoporous Silicon as a Support for High-Performance Protein Microarrays

Abstract

The present work demonstrates the possibilities of using macroporous silicon as a substrate for highly sensitive protein chip applications. The formation of 3D porous silicon structures was performed by electrochemical dissolution of monocrystalline silicon. The fabricated macroporous silicon network has a rigid spongelike structure showing high uniformity and mechanical stability. The microfluidic properties of the substrates were found to be essential for a good bioassay performance. Small spot area, good spot reproducibility, and homogeneous spot profiles were demonstrated on the substrates for immobilized aRIgG. Water contact angles were measured on the porous surface and compared to that of planar silicon, silanized glass, and ordinary microscope glass slides. The effect of the porous surface on the performance of a model IgG-binding immunoassay is presented. aRIgG was microdispensed onto the chip surface forming a microarray of spots with high affinity for the target analyte. The dispensing was performed using an in-house-developed piezoelectric flow-through dispenser. Each spot was formed by a single droplet (100 pL) at each position. The macroporous silicon allowed a high-density microarraying with spot densities up to 4400 spots/cm2 in human plasma samples without cross-talk and consumption of only 0.6 pmol of antibodies/1-cm2 array. Antigen levels down to 70 pM were detected.

Hybrid ZnO Nanorod‐Polymer Brush Hierarchically Nanostructured Substrate for Sensitive Antibody Microarrays

“…Some of such substrates are featured of surface-confi ned nanostructures such as macro-/nanoporous silicon, polymers, and porous alumina with huge surface areas for loading of highly dense antibody to capture more targets over a plain surface. [16][17][18][19] Further attempts exploit fl uorescence-enhancing nanomaterials such as photonic crystals, metals, and metal oxides, [20][21][22][23][24][25][26][27] which are able to intrinsically intensify the emission signal of proximal fl uorophores, besides high surface areas for antibody immobilization, to further improve the signal to noise ratio for sensitive microarray detection. We recently reported a zinc oxide (ZnO) nanorod substrate-enhanced fl uorescence microarray with a detection limit as low as 1 pg mL −1 for cancer biomarkers without additional signal amplifi er.…”

The Quest for High-Speed and Low-Volume Bioanalysis

“…Densities up to 10,000 spots/cm 2 have recently been reported (43). Advantageous wetting properties combined with the higher surface density of the immobilized affinity probe have resulted in considerably improved detection limits for fluorescence microscopy (44). Porous silicon is also known to be compatible with MALDI TOFMS.…”

New directions of miniaturization within the proteomics research area

“…The improved performance is dependent on the morphology of the specific surface. A more detailed report on these protein chip surfaces is given in [67].…”