Assembling Surface Linker Chemistry with Minimization of Non-Specific Adsorption on Biosensor Materials

Abstract

The operation of biosensors requires surfaces that are both highly specific towards the target analyte and that are minimally subject to fouling by species present in a biological fluid. In this work, we further examined the thiosulfonate-based linker in order to construct robust and durable self-assembling monolayers (SAMs) onto hydroxylated surfaces such as silica. These SAMs are capable of the chemoselective immobilization of thiol-containing probes (for analytes) under aqueous conditions in a single, straightforward, reliable, and coupling-free manner. The efficacy of the method was assessed through implementation as a biosensing interface for an ultra-high frequency acoustic wave device dedicated to the detection of avidin via attached biotin. Fouling was assessed via introduction of interfering bovine serum albumin (BSA), IgG antibody, or goat serum. Improvements were investigated systematically through the incorporation of an oligoethylene glycol backbone employed together with a self-assembling diluent without a functional distal group. This work demonstrates that the incorporation of a diluent of relatively short length is crucial for the reduction of fouling. Included in this work is a comparison of the surface attachment of the linker to Si3N4 and AlN, both materials used in sensor technology.

Synthesis of Aminopropyltriethoxysilyl-Substituted Imines and Amides

“…Earlier we had reported that a 4-cyanophenyl aminopropyltriethoxysilyl imine could be prepared and incorporated into a molecular rectifier so we wanted to use this method prepare a number of different imines from benzaldehydes with strong electron withdrawing groups (7) (Scheme 2) [2]. As expected, these reactions proceeded well to produce imines (8)(9)(10)(11) that can be isolated in high yield. As with all of these imines, they are best stored for long periods of time under nitrogen in a refrigerator.…”

“…A series of small molecules containing aminopropyltriethoxysilane (APTES) linkers were synthesized so that they could potentially be incorporated into self-assembled monolayers (SAMS) on metal oxide surfaces. Trialkoxysilanes are widely used to modify metal oxide surfaces since they readily react with surface hydroxyl groups to release the alkanol and provide a piano stool trialkoxysilane linkage to the surface [1][2][3][4][5][6][7][8][9][10][11]. Two main structural aspects of the small molecules to be synthesized were considered: (1) ease of synthesis of the small molecule, i.e., where possible, one-pot reactions from inexpensive, commercially available starting materials, and (2) presentation of a variety of aromatic functional groups that would be of interest to others working to use SAMS as components of materials for molecular electronics or sensing applications.…”

Transparent and Highly Flexible Hierarchically Structured Polydimethylsiloxane Surfaces Suppress Bacterial Attachment and Thrombosis Under Static and Dynamic Conditions

“…[1][2][3] On a larger scale, the presence of pathogens on surfaces within clinical settings often leads to hospitalacquired infections with poor prognoses and high treatment costs. [4] Surface modifications aiming to prevent unwanted biological adhesion have been explored extensively. [5][6][7] In the context of reducing pathogen-related fouling, antibiotic coatings, [8][9][10] nanoparticlebased nanocomposite films, [11,12] and biosurfactant impregnation [13,14] have all been shown to provide varying degrees of suppression of bacterial adhesion.…”

“…[ 1–3 ] On a larger scale, the presence of pathogens on surfaces within clinical settings often leads to hospital‐acquired infections with poor prognoses and high treatment costs. [ 4 ]…”

Detecting Antibody–Antigen Interactions with Chiral Plasmons: Factors Influencing Chiral Plasmonic Sensing

“…Streptavidin specifically binds to these SAMs adopting a well-defined orientation. [43] It should be noted that biotin is also chiral, thus the SAMs will also be chiral. In addition to studying specifically and nonspecifically bound streptavidin, we have also made measurements from complexes formed by them and an antibody.…”