Protein‐enabled detection of ibuprofen and sulfamethoxazole using solid‐state nanopores

Abstract

Enabled by proteins, we present an all-electrical method for rapid detection of small pharmaceuticals (ibuprofen and sulfamethoxazole [SMZ]) in aqueous media using silicon nitride pores. Specifically, we use carrier proteins, bovine serum albumin (BSA), and take advantage of their interactions with two small drug molecules to form BSAdrug complexes which can be detected by nm-diameter pores, thereby confirming the presence of small pharmaceuticals. We demonstrate detection of ibuprofen and SMZ at concentrations down to 100 nM (∼21 μg/L) and 48.5 nM (12 μg/L), respectively. We observe changes in electrical signal characteristics (reflected in event durations, rates, current magnitudes, and estimated particle diameters) of BSA-drug complexes compared to BSA-only, and differences between these two small pharmaceuticals, possibly paving a path toward developing selective sensors by identifying "electrical fingerprints" of these molecules in the future. These distinct electrical signals are likely a combined result of diffusion, electrophoretic and electroosmotic effects, interactions between the pore and particles, which depend on pore diameters, pH, and the resulting surface charges. The use of single-molecule-counting nanopores allows sensing of small pharmaceuticals, studies of protein conformational changes, and may aid in efforts to evaluate the impact of small drug molecules on aquatic and human life.

Silicon Nitride Nanopores Formed by Simple Chemical Etching: DNA Translocations and TEM Imaging

“…(a) Current vs time trace (3.6 s long) after addition of 1 kbp dsDNA at V = 300 mV, all-points histogram, and zoom-in view on one section of the trace. The trace was recorded using a portable nanopore reader from Elements SRL, at 20 kHz bandwidth. ,, The calculated pore diameter from the open pore current is 4.8 nm assuming a thickness of 20 nm. Control measurements with no DNA showed no detectable translocations.…”

“…Nanopores were fabricated in 20 nm and 100 nm thick low-stress SiN x membrane suspended on 250 μm thick, 5 × 5 mm 2 low-noise glass chips (Goeppert LLC, PA). ,, The pores are fabricated following the procedure illustrated in Figure . Briefly, 0.5 μL of 49% HF was administered to individual chips in a consecutive way for 5 s and then aspirated with a pipette.…”

“…We show statistics of effective pore diameters as derived from ionic conductance and total porous area, from zero and sub-nm up to >100 nm. The pores are formed in 20 and 100 nm thick, ∼50 μm diameter SiN x membranes on low-noise glass chips. − We analyzed 26 chips with TEM to further correlate ionic data and TEM. We prove that pore formation is induced by SiN x exposure to μL amounts of HF followed by water rinsing and drying.…”

Advances in miniaturized nanosensing platforms for analysis of pathogenic bacteria and viruses

“…For instance, Drndić and co-workers developed a solid-state nanopore sensor for analysis of ibuprofen and sulfamethoxazole drugs. 64 The analysis is based on interaction of the studied analytes with bovine serum albumin (BSA) protein to form drug–protein complexes that can be detected by a silicon nitride (SiN x ) nanopore chip.…”

Highlights on the current state of proteomic detection and characterization with nanopore sensors

“…Xia et al. [6] offer a similar protein mediated nanopore sensor, but with a major change. They employ custom electronics and a nanofabricated solid‐state pore to detect bovine serum albumin (BSA).…”