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

Abstract

This review highlights the application of different types of nanosilicon (nano-Si) materials and nano-Si-based composites for (bio)sensing applications. Different detection approaches and (bio)functionalization protocols were found for certain types of transducers suitable for the detection of biological compounds and gas molecules. The importance of the immobilization process that is responsible for biosensor performance (biomolecule adsorption, surface properties, surface functionalization, etc.) along with the interaction mechanism between biomolecules and nano-Si are disclosed. Current trends in the fabrication of nano-Si-based composites, basic gas detection mechanisms, and the advantages of nano-Si/metal nanoparticles for surface enhanced Raman spectroscopy (SERS)-based detection are proposed.

Keywords: (bio)sensors; nanocomposites; nanomaterials; silicon.

Figure 1

(a–d) Schematic illustrations of the formation mechanism for synthesizing porous Si films using the MACE process [50]. (e) Electrochemical energy diagram of corresponding reaction. The illustration of the Si NPAs fabrication process [50]. (f) Schematic illustration of the fabrication of SiNP arrays. Close-packed monolayer of polystyrene (PS) nanospheres on a clean Si reduced diameter of PS by reactive ion etching, Au deposition, metal-assisted chemical etching, and the removal of Au/PSi [51].

Figure 2

Scanning electron microscopy images of PSi (a) [4], SiNPs (b) [10], and SiNWs (c) [52].

Figure 3

(a) Bright field (BF) and (b) fluorescence images of J774 macrophage cells on pattern before and after lysis. The dye for cells staining was calcein AM. When the cells were lysed, pores were created on the cell membrane, thus causing the leakage of calcein from the cells. Thus, the fluorescence intensity started to decrease due to the leakage of calcein. Cells were still on the micropatterns after lysis, as can be seen from the BF images. Scale bar 100 μm [75].

Figure 4

(a) The sequence of the 21-mer Si-specific peptide conjugated with the H2 B antigen (the site of acetylation is annotated); (b) Schematic representation of the H2 B glass sensor; (c) The measuring scheme, (d) the red-green-blue (RGB) layers of the obtained colored product; (e) Generation of colored solution by TMB-HRP reaction after capture of H2 B antibody on PSi. Color intensity depends on the concentration of the captured Anti-H₂ B antibody [73].

Figure 5

Scanning electron microscopy (SEM) images of some nano-Si/MOx nanocomposites: (a) SEM images of the PSi/ZnO nanocomposite [125]; (b) SEM images of the SiNWs/WO₃ nanocomposite [126]; (c) SEM image of the SiNPs/TiO₂ nanocomposite [136]; (d) SEM images of the PSi/V₂O₅ nanocomposite [37].

Figure 6

Band diagram of the TiO₂ decorated PSi heterojunction (a) before contact, (b) after contact (in air) [120].

Figure 7

Mechanism diagram of PSi/WO₃/Pd to NH₃: (a) Before Pd loading, (b) After Pd loading [139].

Figure 8

(a) The handheld Raman instrument. (b) SERS spectrum of 0.75 nmol VX and normal Raman spectrum of >98% VX solution [12]; (c) pathways for the in situ detection of pesticide residues on lemon peels using flexible SiNPs/Au [184].

Figure 9

Schematic illustration showing (a) initial state of PSi/graphene substrate and formation of the depletion layer, (b) the adsorption-desorption process of H₂ [194].