A novel approach for osteocalcin detection by competitive ELISA using porous silicon as a substrate

Abstract

In this study, porous silicon (PSi) was utilized instead of prevalent polystyrene platforms, and its capability in biomolecule screening was examined. Here, two types of porous structure, macroporous silicon (Macro-PSi) and mesoporous silicon (Meso-PSi), were produced on silicon wafers by electrochemical etching using different electrolytes. Moreover, both kinds of fresh and oxidized PSi samples were investigated. Next, osteocalcin as a biomarker of the bone formation process was used as a model biomarker, and the colorimetric detection was performed by competitive enzyme-linked immunosorbent assay (ELISA). Both Macro-PSi and Meso-PSi substrates in the oxidized state, specifically the Meso-porous structure, were reported to have higher surface area to volume ratio, more capacitance of surface-antigen interaction, and more ability to capture antigen in comparison with the prevalent platforms. Moreover, the optical density signal of osteocalcin detected by the ELISA technique was notably higher than the common platforms. Based on the findings of this study, PSi can potentially be used in the ELISA to achieve better results and consequently more sensitivity. A further asset of incorporating such a nanometer structure in the ELISA technique is that the system response to analyte concentration could be maintained by consuming lower monoclonal antibody (or antigen) and consequently reduces the cost of the experiment.

Nanosilicon-Based Composites for (Bio)sensing Applications: Current Status, Advantages, and Perspectives

“…As mentioned below, biofunctionalization plays a very important role in bioselective layer evolution and allows for the binding of organic molecules to a non-organic nano-Si surface without unspecific interaction. Currently, a number of biofunctionalization protocols have been proposed: silanization [3,19,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67], aminosilanization [68,69,70], direct immobilization [16,22,71,72], enzyme [18] or peptide [73] treatment, phospholipid bilayers formation [74], hydrosilylation treated by N-Hydroxysuccinimide and 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (NHS/EDC) [75,76,77] or resazurin [78], and polymer synthesis [79]. However, the most common technique is silanization, due to the possibility of controlling the thickness of the(3-Aminopropyl)triethoxysilane (APTES) layer as well as using different cross-linking agents (glutaraldehyde, NHS/EDS) [18,80].…”

“…Another nano-Si optical response suitable for (bio)molecule detection is reflectance or other optical parameters related to reflectance [22,48,53,55,56,57,58,62,65,67,68,70,71,74,76,85,86,87,88,89,90,91,92,93,94,95,96]. Generally, the (bio)sensor technique based on reflectance response can be performed via reflective index (RI) [71] or optical density [16] (OD) measurements in the initial state and after the addition of the analyte. The changes in RI and OD caused by analyte-transducer surface interaction can be processed and used as the effective (bio)sensor signal.…”

“…Nowadays, sensors and biosensors based on nano-Si have been successfully applied to molecules [15], biomolecules [16] and light [17] detection using different responses (PL [18,19], SERS [20], I–V [21], reflectance [22,23], resistance [24], capacitance [25], fluorescence [26]) and material modifications (PSi, SiNWs, SiNPs). Such strong interest in (bio)sensors based on nano-Si can be explained by their enhanced surface to volume ratio, biocompatibility, and low-cost.…”