Alkanethiol Self-assembled Monolayers Research Articles

Optimization of Fc-Thiolate SAMs for Electrochemically Mediated Bacterial Biosensors

Alkanethiol Self-Assembled Monolayers (SAMs), typically deposited on Au substrates, have been commonly utilized to immobilize receptor biomolecules in the construction of a variety of biosensors, such as the detection of glucose oxidase by the immobilization of calixarenes thiols 1. The appeal of using SAMs derives from their ease of fabrication and component flexibility, allowing for more than one alkanethiol to be deposited in a single monolayer. This results in the formation of SAMs in which each thiol component adds a different property or role, thus introducing versatility to the construction and operation of resulting sensors 2.In our recent work, alkanethiol SAMs, composed of three different thiol molecules, were constructed for use as an electrochemical Toll-Like Receptor 4 (TLR4)-based sensor that can detect Gram-negative bacteria. TLRs are a family of immunoproteins in the innate immune system, which are able to detect a broad category of pathogens, rather than specific targets, as is the case with the adaptive system (e.g., antibodies). In our published work 3, SAMs consisted of a carboxylic acid terminated thiol that allowed for the conversion to a nitrilotriacetic (NTA) group. This moiety could then chelate a Ni2+ cation, followed by attachment of the TLR4 immunoprotein via its His-tag. The second thiol in the SAM contained a terminal ferrocene (Fc) group, where the Fc group was bound to the C11 chain via an amide group. Here, the Fc group serves as a mediator for charge transfer between ferrocyanide in solution and the Au substrate, resulting in relatively high current signals, thus making the sensor potentially field deployable. The third thiol in these SAMs was a hydroxy-terminated thiol, added as a diluent between the immobilized TLR4 receptors. SAMs were prepared by co-deposition on sputter Au on glass.Electrochemical testing involved cyclic voltammetry (CV) studies in pH 7 buffer solution in order to determine the amount of Fc-thiol present, as well as CV and electrochemical impedance spectroscopy (EIS) studies in ferrocyanide solutions to examine its redox-mediation response and to obtain a measure of the charge transfer rate. In the presence of lysed bacteria, the immobilized TLR4 dimerizes, which blocks electrochemical mediation between ferrocyanide and the surface bound Fc. This results in an increase in RCT which is our biosensor signal. However, a key problem with these sensors is that their RCT increased with electrochemical testing in the absence of lysed bacteria, producing signal drift. Thus, in the present work, the reasons for sensor signal drift and methods to overcome it were explored.It was found in recent work that the drift of the full TLR4 sensor was correlated with the loss in the Fc redox signal, although it was not clear if underlying SAM was at the root of the problem. If so, then it was necessary to determine if the loss in the Fc redox activity was caused by the physical loss of the Fc thiol from the Au surface or deactivation of the Fc surface complex and/or its electrochemistry. To determine which of these options was responsible for signal drift, the relative % v/v fraction of the three thiols was varied, and in later work, based on chemical considerations, the Fc molecule containing an amide group was replaced with a C11 chain bonded directly to the Fc. It was found that this latter strategy led to a very stable SAM, showing negligible drift in the Fc CV charges and in the RCT values in ferrocyanide solutions, with or without the TLR4 receptor attached on the outer surface of the SAM.This presentation will focus on presenting the electrochemistry of the various binary and ternary thiol SAMs investigated in this work and examining the Fc CV peak charges, potential, and kinetics, as well as the double layer capacitance, to better understand how and why the Fc redox response was stabilized. This is important because this correlates directly with the stability of the TLR4/Gram-negative bacteria sensor, as will be demonstrated for a TLR2 biosensor tested against Gram-positive bacteria cell wall ligands.

Self-assembly of octanethiol on oxide-free cobalt electrode from aqueous solution under electrochemical control

Self-assembly of alkanethiols on Co surface from organic solution has met with limited success due to the presence of the native oxides. A way needs to be found to remove any oxide and form perfect self-assembled monolayers (SAMs). We report the development of electrochemical approach for formation of alkanethiol self-assembled monolayers on base metals in aqueous solutions. For formation of octanethiol (OT) SAMs on oxide-free cobalt surfaces, we combine the surface renewal technique with in situ electrochemical procedure of removing the native oxide, thiol adsorption, and electrochemical control of SAMs properties in one aqueous solution. The use of aqueous thiol-containing media results in removing any oxide by electrochemical reduction, accelerated monolayer formation under electrochemical control, and investigating SAMs surface coverage and monolayer integrity by voltammetry. In this work, we study the influence of different factors on self-assembly process such as the surface pretreatment, adsorption time, the presence of dissolved oxygen, solution pH, and potential cycling on polycrystalline cobalt microelectrode from aqueous 0.1 M NaClO4 solutions of 0.1 mM OT. We obtain the high-quality self-assembled monolayers which are stable in wide range of potentials and show blocking characteristics toward the following Faradaic processes: Co surface oxidation and O2 and H+ reduction.

Force Field Parameter Development for the Thiolate/Defective Au(111) Interface.

A molecular-level understanding of the interplay between self-assembled monolayers (SAMs) of thiolates and gold surface is of great importance to a wide range of applications in surface science and nanotechnology. Despite theoretical research progress of the past decade, an atomistic model, capable of describing key features of SAMs at reconstructed gold surfaces, is still missing. In this work, periodic ab initio density functional theory (DFT) calculations were utilized to develop a new atomistic force field model for alkanethiolate (AT) SAMs on a reconstructed Au(111) surface. The new force field parameters were carefully trained to reproduce the key features, including vibrational spectra and torsion energy profiles of ethylthiolate (C2S) in the bridge or staple motif model on the Au(111) surface, wherein, the force constants of the bond and angle terms were trained by matching the vibrational spectra, while the torsion parameters of the dihedral angles were trained via fitting the torsion energy profiles from DFT calculations. To validate the developed force field parameters, we performed classical molecular dynamics (MD) simulations for both pristine and reconstructed Au-S interface models with a (2√3 × 3) unit cell, which includes four dodecanethiolate (C10S) molecules on the Au(111) surface. The simulation results showed that the geometrical features of the investigated Au-S interface models and structural properties of the C10S SAMs are in good agreement with the ab initio MD studies. The newly developed atomistic force field model provides new fundamental insights into AT SAMs on the reconstructed Au(111) surface and adds advancement to the existing interface research knowledge.

Simulation of Subnanometer Contrast in Dynamic Atomic Force Microscopy of Hydrophilic Alkanethiol Self-Assembled Monolayers in Water

Atomic resolution imaging of surfaces in liquid environments using atomic force microscopy (AFM) is challenging in terms of both reproducibility and measurement interpretation. To understand the origins of these challenges, we used molecular dynamics simulations of AFM on hydrophilic self-assembled monolayers (SAMs) in water. The force on the model AFM tip was calculated as a function of lateral and vertical position relative to the SAM surface. The contributions of the water and SAMs to the overall force were analyzed, and the former was correlated to the water density distribution. Then, dynamic AFM was modeled by oscillating the tip at a driving amplitude. It was found that the contrast between amplitudes at different lateral positions on the surface was dependent on the vertical position of the tip. Lastly, amplitude maps were produced for two vertical positions at constant height, and the ability to capture atomic resolution was related to the force on the tip. These results offer an explanation for the observed instability in atomic scale imaging using AFM and more generally provide insight into the contrast mechanisms of surface images obtained in liquid environments.

Scalable Fabrication of Quasi-One-Dimensional Gold Nanoribbons for Plasmonic Sensing.

Plasmonic nanostructures have a wide range of applications, including chemical and biological sensing. However, the development of techniques to fabricate submicrometer-sized plasmonic structures over large scales remains challenging. We demonstrate a high-throughput, cost-effective approach to fabricate Au nanoribbons via chemical lift-off lithography (CLL). Commercial HD-DVDs were used as large-area templates for CLL. Transparent glass slides were coated with Au/Ti films and functionalized with self-assembled alkanethiolate monolayers. Monolayers were patterned with lines via CLL. The lifted-off, exposed regions of underlying Au were selectively etched into large-area grating-like patterns (200 nm line width; 400 nm pitch; 60 nm height). After removal of the remaining monolayers, a thin In2O3 layer was deposited and the resulting gratings were used as plasmonic sensors. Distinct features in the extinction spectra varied in their responses to refractive index changes in the solution environment with a maximum bulk sensitivity of ∼510 nm/refractive index unit. Sensitivity to local refractive index changes in the near-field was also achieved, as evidenced by real-time tracking of lipid vesicle or protein adsorption. These findings show how CLL provides a simple and economical means to pattern large-area plasmonic nanostructures for applications in optoelectronics and sensing.

Structural Phases of Alkanethiolate Self-Assembled Monolayers (C1–12) on Cu[100] by Density Functional Theory

The structure and as such the properties of alkanethiolate self-assembled monolayers (SAMs) on metal surfaces depend on the surface structure, thiolate coverage, and chain length. The chain length ...

Modulating the Electronic Properties of Au–MoS2 Interfaces Using Functionalized Self-Assembled Monolayers

Molybdenum disulfide (MoS2) is a transition-metal dichalcogenide with many applications including in electronic devices and sensors. A critical issue in the development of these devices is the high resistance between the metal contact and the molybdenum disulfide layer. In this study, we employ Raman spectroscopy and X-ray photoelectron spectroscopy to investigate the modification of Au-MoS2 contact properties using functionalized alkanethiolate self-assembled monolayers (SAMs). We demonstrate that both 2H and 1T MoS2 strongly interact with the underlying Au substrate. The electronic properties of the interface are mediated by the dipole moment of the alkanethiolate SAM, which have a -CH3, -CO2C6F5, -OH, or -COOH terminal group. Finally, we demonstrate the site-selective deposition of 2H and 1T MoS2 on micropatterned SAMs to form conducting-semiconducting patterned MoS2 films.

A Tribute to Richard M. Crooks on the Occasion of His 65th Birthday

A Tribute to Richard M. Crooks on the Occasion of His 65th Birthday

Homogeneous functional self-assembled monolayers: Faradaic impedance baseline signal drift suppression for high-sensitivity immunosensing of C-reactive protein

The limit of detection (LOD) of affinity sensors based on alkanethiol self-assembled monolayers (SAMs) system can be improved by either signal amplification and/or noise reduction. The latter includes baseline signal drift arising, in part, from, monolayer imperfections (and variations in this through repeats) as well as electrical noise of both the sensor and transducer. In reagentless “label free” assays signal drift carries with it the possibility of assay false-positive results (if signal drift is positive) or false-negatives (if specific signal is swamped by downward drift). Faradaic electrochemical impedance spectroscopy (FEIS) sensors based on SAM interfaces have been shown to exhibit considerable baseline signal drift, which consequently affects their assaying capabilities. This study reports on the development of a simple two-step pre-treatment method for generating functional SAMs of 11-mercaptoundecanoic acid (MUA) on Au with a highly suppressed baseline signal drift. For electrochemical characterisation of the SAMs, the charge-transfer resistance (Rct), defect presence (pinhole radius and separation), capacitance, and dielectric constant were evaluated. The interface pre-treatment generates films of substantially improved homogeneity that are subsequently functionalised with anti-human C-reactive protein. CRP, an acute-phase protein, is detectable down to femtomolar levels without any amplification; this is a 2–3 order of magnitude lower detection limit than that typically accessible for analyses of this type. The developed protocols thus present a convenient and general route to suppress baseline signal drifts and improve the limits of detection of affinity sensors based on Faradaic impedance.

Modification of Self-Assembled Monolayers by Electron Irradiation: The Effect of Primary Energy (10–500 eV)

Well-defined alkanethiolate self-assembled monolayers (SAMs) represent a useful model system for a variety of thin organic films on solid supports, in particular in the context of their modificatio...

Chain-Length-Dependent Reactivity of Alkanethiolate Self-Assembled Monolayers with Atomic Hydrogen

Gas–surface interactions are some of the most important yet complex chemical processes to occur, as they intrinsically involve many-body phenomena across a wide spectrum of energies and length scales. To understand these complicated interfacial interactions, we often use model systems such as thiolate self-assembled monolayers (SAMs) to study phenomena like reactivity and passivation, as these systems afford fine control over the surface parameters governing the events in question. In this study, we examine the effect of chain length on the reactivity of alkanethiolate SAMs with atomic hydrogen by monitoring morphological surface evolution throughout the reaction. These spatiotemporal data were obtained using ultrahigh vacuum scanning tunneling microscopy (UHV-STM) with directed in situ atomic hydrogen dosing. For a series of alkanethiolate SAMs 8- to 11-carbons long, we find that small increases in chain length cause disproportionately large decreases in reactivity. These reaction trends led us to develop a kinetic model characterized by two rate constants: a slow rate for hydrogen reactivity with close-packed domains, which is chain-length dependent, and a fast rate for reactivity with low-density regions, which is the same for all samples examined. In addition to reaction rates, we also tracked chain-length-dependent changes in surface morphology, notably how the size and shape of the SAMs’ etch pits evolved following hydrogen exposure. Few differences were observed in the 10C and 11C samples, while there was a significant increase in the mean etch pit area of the 8C and 9C SAMs. Overall, this study provides important quantitative insights into how surface packing and dynamic disorder of organic thin films can influence their passivation capabilities.

Adsorption of Amyloidogenic Peptides to Functionalized Surfaces Is Biased by Charge and Hydrophilicity.

Surfaces are abundant in living systems, such as in the form of cellular membranes, and govern many biological processes. In this study, the adsorption of the amyloidogenic model peptides GNNQQNY, NNFGAIL, and VQIVYK as well as the amyloid-forming antimicrobial peptide uperin 3.5 (U3.5) were studied at low concentrations (100 μM) to different surfaces. The technique of a quartz crystal microbalance with dissipation monitoring (QCM-D) was applied as it enables the monitoring of mass binding to sensors at nanogram sensitivity. Gold-coated quartz sensors were used as unmodified gold surfaces or functionalized with self-assembled monolayers (SAMs) of alkanethiols (terminated as methyl, amino, carboxyl, and hydroxyl) resulting in different adsorption affinities of the peptides. Our objective was to evaluate the underlying role of the nature and feature of interfaces in biological systems which could concentrate peptides and impact or trigger peptide aggregation processes. In overall, the largely hydrophobic peptides adsorbed with preference to hydrophobic or countercharged surfaces. Further, the glycoprotein lubricin (LUB) was tested as an antiadhesive coating. Despite its hydrophilicity, the adsorption of peptides to LUB coated sensors was similar to the adsorption to unmodified gold surfaces, which indicates that some peptides diffused through the LUB layer to reach the underlying gold sensor surface. The LUB protein-antiadhesive is thus more effective as a biomaterial coating against larger biomolecules than small peptides under the conditions used here. This study provides directions toward a better understanding of amyloid peptide adsorption to biologically relevant interfaces, such as cellular membranes.

Probing the Redox-Dependent Electronic and Interfacial Structures in Ferrocene-Terminated Self-Assembled Monolayers with Photoelectron Spectroscopy

Central to electrochemistry is the electric double layer (EDL) at the electrode-electrolyte interface where important interfacial phenomena including adsorption and charge transfer occur.1 Understanding the nature of the electric double layer regarding the electronic and structural characteristics has implications relating to bio(chemical) sensors, micro-mechanical actuators and energy storage/conversion devices. Amongst model systems, ferrocene-terminated alkanethiol self-assembled monolayers (Fc SAM) on Au are an attractive model electrochemical interface due to their practical applicability and versatility with structural modifications.2 Within the Fc SAM, a change in the ferrocene/ferrocenium (Fc/Fc+) redox state leads to notable changes to the interfacial structure with respect to the EDL, interactions with the electrolyte, and work function. While existing studies exist on probing the redox-induced Fc SAM structural changes using techniques such as surface plasmon resonance (SPR), Raman, IR and quartz crystal microbalance (EQCM),2 experimental efforts aimed at probing the changes in electronic structure are still limited. Here, we employ X-ray and ultraviolet photoelectron spectroscopy combined with an electrochemical cell (EC-XPS/UPS) which allows us to electrochemically control the Fc SAM redox state and spectroscopically probe the redox-induced electronic and structural changes.3 To perform our experiments, electrochemical (EC) measurements are performed in a separate EC chamber in Ar atmosphere followed by evacuation and then transfer to the XPS/UPS analysis chamber.4 The EC chamber contains a retractable PTFE (polytetrafluorethylene) cell where electrochemical measurements are performed under Ar atmosphere. The cell utilizes a hanging meniscus setup connected via PFA (perfluoroalkoxy alkane) tubing to a syringe containing the electrolyte. This controlled setup permits us to reliably probe the oxidized Fc+ moieties and prevent its decomposition upon exposure to the ambient. Using this approach, following EC and electrode immersion, we can probe changes to the ferrocene/ferrocenium (Fc/Fc+) redox center (Fe oxidation state), deduce the occurrence of ion-pairing, changes in molecular orientation and monolayer thickness (Figure 1). Oxidation to Fc+ is corroborated by UPS, which shows that a shift of the highest occupied molecular orbital (HOMO) towards higher binding energy along with an increase in work function. The reversibility of our observations is confirmed by reproducibly switching between the Fc/Fc+ states. More broadly, our approach is potentially applicable to a variety of electrochemically active systems to assist in the elucidation of redox-related structure-function relationships. Specific details will be provided during the presentation. Figure 1. (a) Schematic and photographs of hanging meniscus inside the EC chamber during EC measurements and following removal from the electrolyte. (b) Molecular structure of Fc SAM used in study and cyclic voltammagram performed in 0.1 M NaClO4. (c) Corresponding XPS Fe 2p, Cl 2p and O 1s spectra of the pristine, oxidized Fc+ and neutral Fc states. Kolb, D. M. Angew. Chem. Int. Ed. 2001, 40, 1162.K. Uosaki, Electrochemistry 1999, 12, 1105.R. A. Wong, Y. Yokota, M. Wakisaka, J. Inukai, Y. Kim, J. Am. Chem Soc. 2018, 140, 13672.M. Wakisaka, S. Mitsui, Y. Hirose, K. Kawashima, H. Uchida, M. Watanabe, J. Phys. Chem. B 2006 , 46, 23489. Figure 1

Low energy electron interactions with 1-decanethiol self-assembled monolayers on Au(111)

Understanding the interaction of low energy electrons with organic thin films is important for the development of a wide range of technological applications. In this study, the interaction of 80 eV electrons with self-assembled monolayers (SAMs) of 1-decanethiol grown on Au(111) via vapor phase deposition was explored for both the lying down (striped) phase and the standing up phase. Low-energy electron diffraction measurements performed at 100 K show that the SAM loses its crystalline structure within about 3 min for the lying down phase and approximately 30 s for the standing up phase. For the standing up phase, temperature programed desorption measurements reveal two desorption features for the hydrocarbon fragments of the SAM, one centered around 130 °C and a second near 220 °C. For the lying down phase, only the higher temperature desorption feature is observed. For both phases, desorption peaks for S and H2S that are centered around 250 °C were observed, suggesting that there is a high probability for the alkane chain of the 1-decanethiol molecule to detach from the sulfur head group before desorbing from the surface. For the standing up phase, exposing the SAM to the electron beam results in a near complete attenuation of the two peaks associated with the cracking fragments of the alkane chain. However, for the lying down phase, the intensities and positions of all of the desorption peaks were similar to the unexposed SAMs, which indicates that the cross section for electron beam damage for the lying down phase is much lower than that for the standing up phase. Ex situ x-ray photoelectron spectroscopy reveals a chemical shift of almost 0.5 eV for the C-1s emission after electron exposure for the standing up phase, whereas the shift for the lying down phase was less than 0.1 eV. These results indicate that exposure of alkanethiol SAMs to 80 eV electrons results in both disordering of the SAM and decomposition of the alkanethiol molecule SAMs. For the standing up phase, the rate of decomposition is much higher than the lying down phase. The lower decomposition rate for the lying down phase is primarily attributed to the quenching of excess charge in this phase since the entire molecule is in direct contact with the metallic substrate.

Elektrokimyasal Biyosensörlerin Geliştirilmesinde Alkanetiol Kendiliğinden Oluşan Tek Katmanlar ile Peptid Nükleik Asit (PNA) Probu

Alkanethiol self-assembled monolayers (SAMs) with Peptide Nucleic Acid (PNA) were proposed as a novel probe design in electrochemical biosensors. This paper investigates the optimization of PNA probe by using two different concentrations of SAMs, immobilization temperature, and two-stage immobilization process. Alkanethiol self-assembled monolayers with PNA probe immobilization and cDNA (complementary DNA) hybridization were measured via AC voltammetry method. The small negative shift in formal potential (-17 mV) was occurred after cDNA hybridization at high ionic strength concentration.

Comparison of Inorganic and Organic Acid Etching Processes on Germanium(100)

Ge(100) surfaces were cleaned in aqueous hydrochloric and citric acids. X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry were used to measure the surface composition and film thickness, respectively. Alkanethiolate self-assembled monolayers were formed after each acid treatment to assess oxide removal since sulfur only bonds with elemental Ge. XPS showed that sonication is required to remove citric acid species which remain on the surface after etching. The residual citric acid on the surface inhibits the liquid phase deposition of the alkanethiol layer likely by physically blocking surface sites. Aqueous hydrochloric acid etching removed more oxides from the surface, and the alkanethiol formed a dense monolayer.

Deviation from Point Dipole Analysis for Exciton Quenching in Quaterthiophene-Terminated Self-Assembled Monolayers on Au(111)

A geometry-specific analysis of exciton quenching in the quaterthiophene (4T)-terminated alkanethiolate self-assembled monolayers (4TCnS-SAMs, where n is the number of methylene units; n = 3, 5, 6,...

Self-Assembled Monolayers of Alkanethiol as Inhibitors against Copper Corrosion in Synthetic Acid Rain

Self-Assembled Monolayers of Alkanethiol as Inhibitors against Copper Corrosion in Synthetic Acid Rain

Precise control of nanoscale spacing between electrodes using different natured self-assembled monolayers

Herein, we introduce an interdigitated horizontal electrode (IHE) structure with a metal-based electron-collecting (or -injecting) electrode and a hole-collecting (or -injecting) electrode composed of a conductive polymeric material that has a nanoscale distance and is horizontally separated. In the IHE, a metal electrode is fabricated on a silicon-oxide substrate, and a self-assembled monolayer (SAM) is selectively bonded to the metal and the oxide to form a conductive polymer electrode by dip coating. Each of the SAM materials is composed of a head part bonded to the substrate surface and a tail part that is hydrophilic or hydrophobic. This inherent property makes the metal electrode hydrophobic and the oxide substrate hydrophilic. Ag is used as a metal electrode material and is combined with alkanethiol SAMs. The alkylsilane SAMs are combined with the silicon oxide substrate to make them hydrophilic, using poly (3, 4-ethylenedioxythiophene)-poly (PEDOT: PSS) as the conductive polymer material. In this study, we have found that there is a difference in the spacing between the two electrodes that depends on the combination of SAM materials. Each interval was spaced from a minimum of 140 nm to a maximum of 385 nm.

Wastewater biofilm formation on self-assembled monolayer surfaces using elastomeric flow cells

In anaerobic wastewater treatment, microbial biofilm is beneficial for efficient substrate utilization and for preventing the wash-out of key microorganisms. By providing solid supports, biofilm formation can be accelerated due to the early initial adhesion of residing microbes. Alteration in surface properties is therefore one such approach that helps us understand microbial interfacial interaction. Here, self-assembled monolayers of alkanethiols with carboxyl (-COOH), hydroxyl (-OH), and amine (-NH2) terminal moieties on gold (Au) substrates were employed to study the initial adhesion of wastewater microbes. An elastomeric flow cell was also utilized to simulate the environment of wastewater bioreactor. Results from fluorescence in situ hybridization (FISH) portrayed more enhanced microbial adhesion after 2 h on -NH2 functional group with the calculated surface coverage of 12.8 ± 2.4% as compared to 7.7 ± 1.6% on -COOH, 11.0 ± 2.0% on -OH, and 1.2% on unmodified Au surfaces. This might be because of concomitant electrostatic attraction between negatively-charged bacteria and positively-charged (-NH3+) functional groups. Nevertheless, the average surface coverage by individual biofilm clusters was 28.0 ± 5.0 μm2 and 32.0 ± 9.0 μm2 on -NH2 and -OH surfaces, respectively, while -COOH surfaces resulted in higher value (60.0 ± 5.0 μm2) and no significant cluster formation was observed on Au surfaces. Accordingly, the average inter-cluster distance observed on -NH2 surfaces was relatively smaller (3.0 ± 0.6 μm) as compared to that on other surfaces. Overall, these data suggest favorable initial biofilm growth on more hydrophilic and positively-charged surfaces. Furthermore, the analysis of the mean fluorescence intensity revealed preferred initial adhesion of key microbes (archaea) on -OH and -NH2 surfaces. Indeed, results obtained from this study would be beneficial in designing selective biointerfaces for certain biofilm carriers in a typical wastewater bioreactor. Importantly, our elastomeric flow cell integrated with SAM-modified surfaces demonstrated an ideal platform for high-throughput investigation of wastewater biofilm under controlled environments.