Investigation of Silicon-Based Nanostructure Morphology and Chemical Termination on Laser Desorption Ionization Mass Spectrometry Performance

Abstract

We have evaluated the laser desorption ionization mass spectrometry (LDI-MS) performance of six nanostructured silicon surfaces of different morphologies and chemical functionalizations. The substrates have been synthesized either by metal-assisted etching method or by vapor-liquid-solid (VLS) growth technique. In addition to the commercial nanostructured silicon-based surface (NALDI) target plates, serving as reference, the homemade surfaces have been evaluated in mass spectrometry experiments conducted with peptide solutions mimicking tryptic digests. LDI surfaces synthesized by metal-assisted etching method were the most efficient in terms of signal intensities and number of detected peptides. The surface providing the best LDI-MS performance was composed of two nanostructured layers. Interestingly, we also observed a significant influence of the type of organic coating (hydrocarbon vs fluorocarbon) on peptide ionization discrimination.

Bio-Inspired Extreme Wetting Surfaces for Biomedical Applications

“…These findings suggested that lotus leaf-like highly water-repellent superhydrophobic surfaces can be fabricated using micro/nano hierarchical structures coated with low-surface-energy materials. Inspired by the lotus leaves, various methods such as wet chemical etching [33,34,35,36,37,38], electrochemical reaction [39,40,41], lithography [42,43,44], electrodynamics [45,46,47], sol-gel methods [48,49,50,51,52], layer-by-layer deposition [53,54,55], and plasma treatment [56,57,58,59] have been developed to produce these surfaces. Jiang et al reported an electrohydrodynamics technique as a versatile and effective method to fabricate polystyrene (PS) composite film combining porous microspheres and inter-woven nanofibers [60].…”

Vertical SiNWAs for biomedical and biotechnology applications

“…65 Due to the non-adhesiveness of PEG hydrogels toward proteins, proteins were selectively immobilized on the pre-modied SiNWAs regions to create protein micropatterns. 67,68 Compared with other conventional LDI-MS substrates, the SiNWAs exhibit several advantages, such as excellent light trapping ability over a broad wavelength range, high efficiency of light-to-heat conversion to desorb/ionize analytes (such as proteins and peptides), large surface area to allow for the retention of analytes, and an open interwire space to allow the ionized analytes to leave, making them good substrates for the LDI-MS analysis of small biomolecules. Immunobinding assays between IgG and anti-IgG and between IgM and anti-IgM that were performed on the micropatterned SiNWAs emitted stronger uorescent signals and exhibited higher sensitivities compared with those performed on smooth silicon substrates.…”

Mechanisms of Nanophase-Induced Desorption in LDI-MS. A Short Review

“…Pd nanostructured materials, such as PdNPs deposited onto porous silicon, showed low reflectivity, which corresponded to good LDI performance [79]. Such parameter has also been considered for Si-based materials in several works [76,80,81,82]. …”

“…In particular, the role of different shapes (spheres, rods, and stars) of AuNPs [75] as well as the role of morphology of Pd [79] (Figure 9) and Pt nanostructured materials [87,88] were investigated. Several groups also carried out similar works on Si-based materials [81,82,89]. It is generally accepted that sub-micrometer roughness (or porosity) and high surface area are essential to achieve acceptable ion desorption efficiencies [80,90,91].…”