Surface-assisted laser desorption/ionization mass spectrometry using ordered silicon nanopillar arrays

Abstract

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is ideally suited for the high-throughput analysis of small molecules in bodily fluids (e.g. saliva, urine, and blood plasma). A key application for this technique is the testing of drug consumption in the context of workplace, roadside, athlete sports and anti-addictive drug compliance. Here, we show that vertically-aligned ordered silicon nanopillar (SiNP) arrays fabricated using nanosphere lithography followed by metal-assisted chemical etching (MACE) are suitable substrates for the SALDI-MS detection of methadone and small peptides. Porosity, length and diameter are fabrication parameters that we have explored here in order to optimize analytical performance. We demonstrate the quantitative analysis of methadone in MilliQ water down to 32 ng mL(-1). Finally, the capability of SiNP arrays to facilitate the detection of methadone in clinical samples is also demonstrated.

Pyrylium Salts as Reactive Matrices for MALDI-MS Imaging of Biologically Active Primary Amines

“…However, different MALDI matrices have different ionization/desorption characteristics and may not enable adequate ionization of the target analyte. More complex techniques and tools have, therefore, been developed, which include nanostructure initiator mass spectrometry (NIMS) [11,12], ionic matrices [13,14], desorption ionization from porous silicon (DIOS) [15,16], and surface-assisted laser desorption ionization [17][18][19]. Despite some successes, these methods have never been as widely used as conventional MALDI because of technical and practical limitations, some of which are particularly problematic in imaging applications.…”

Versatile Particle-Based Route to Engineer Vertically Aligned Silicon Nanowire Arrays and Nanoscale Pores

“…Among the range of explored nanomaterial structures, VA-SiNW arrays constitute a prime example, where the presence of controlled nanoscale topography holds the key to a large range of diverse applications, from multi-spectral imaging 3 to the development of nanobio-cellular interfaces 4 . In all cases, control on the geometrical parameters of the nanowires (NWs) holds the key to their successful application and integration in devices [5][6][7] . For the specific case of cellnanotopography interactions, VA-SiNW arrays have proven to play a central role in controlling cellular function and behavior based on the geometry of the NWs 8 .…”

Nanoneedle-Based Sensing in Biological Systems

“…Peptides and small molecules desorb from these substrates efficiently, enabling their detection with a performance comparable to regular MALDI approaches, but without the interfering signal from the matrix. Parameters such as the length of the needles, their spacing, their porosity, and their surface tension have strong effect on the performance of the substrate 83,84 . With this approach, nanoneedle arrays can detect the presence and concentration of illicit drugs in body fluid samples with a limit of detection as low as 32 ng/ml 84 .…”

“…Parameters such as the length of the needles, their spacing, their porosity, and their surface tension have strong effect on the performance of the substrate 83,84 . With this approach, nanoneedle arrays can detect the presence and concentration of illicit drugs in body fluid samples with a limit of detection as low as 32 ng/ml 84 . With the sandwich assay approach 7 , it is possible to detect the addition and removal of phosphate groups from the peptides immobilized to the nanoneedles by mass spectrometry.…”