Self-assembled Monolayers Research Articles

Self-Assembled Monolayer Transporters Enable Reagentless Analysis of Small Molecule Analytes.

The detection of small molecules beyond glucose remains an ongoing challenge in the field of biomolecular sensing owing to their small size, diverse structures, and lack of alternative non-enzymatic sensing methods. Here, we present a new reagentless electrochemical approach for small molecule detection that involves directed movement of electroactive analytes through a self-assembled monolayer to an electrode surface. Using this method, we demonstrate detection of several physiologically relevant small molecules as well as the capacity for the system to operate in several biological fluids. We anticipate that this mechanism will further improve our capacity for small molecule measurement and provide a new generalizable monolayer-based technique for electrochemical assessment of various electroactive analytes.

Investigation of G-Quadruplex DNA-Mediated Charge Transport for Exploring DNA Oxidative Damage in Telomeres.

The human telomeric DNA 3' single-stranded overhang comprises tandem repeats of the sequence d(TTAGGG), which can fold into the stable secondary structure G-quadruplex (G4) and is susceptible to oxidative damage due to the enrichment of G bases. 8-Oxoguanine (8-oxoG) formed in telomeric DNA destabilizes G4 secondary structures and then inhibits telomere functions such as the binding of G4 proteins and the regulation of the length of telomeres. In this work, we developed a G4-DNA self-assembled monolayer electrochemical sensing interface using copper-free click chemistry based on the reaction of dibenzocyclooctyl with azide, resulting in a high yield of DNA tethers with order and homogeneity surfaces, that is more suitable for G-quadruplex DNA charge transport (CT) research. At high DNA coverage density surfaces, G-quadruplex DNA is 4 times more conductive than double-stranded DNA owing to the well-stacked aromatic rings of G-quartets acting as good charge transfer channels. The effect of telomeric oxidative damage on G-quadruplex-mediated CT is investigated. The accommodation of 8-oxoG at G sites originally in the syn or anti conformation around the glycosyl bond in the nonsubstituted hTel G-quadruplex causes structural perturbation and a conformational shift, which disrupts the π-stack, affecting the charge transfer and attenuating the electrochemical signal. The current intensity was found to correlate with the amount of 8-oxodG, and the detection limit was estimated to be approximately one lesion in 286 DNA bases, which can be converted into 64.7 fmol on the basis of the total surface DNA coverage. The improved G4-DNA order and homogeneity sensing interface represent a major step forward in this regard, providing a reliable and controlled electrochemical platform for the accurate measurement and diagnosis of G4-DNA oxidative damage.

Real-time monitoring of voltage-responsive biomolecular binding onto electro-switchable surfaces.

Voltage-responsive biosensors capable of monitoring real-time adsorption behavior of biological analytes onto electroactive surfaces offer attractive strategies for disease detection, separations, and other adsorption-dependent analytical techniques. Adsorption of biological analytes onto electrically switchable surfaces can be modelled using neutravidin and biotin. Here, we report self-assembled monolayers formed from voltage-switchable biotinylated molecules on gold surfaces with tunable sensitivity to neutravidin in response to applied voltages. By using electrochemical quartz crystal microbalance (EQCM), we demonstrated real-time switchable behavior of these bio-surfaces and investigate the range of sensitivity by varying the potential of the same surfaces from -400 mV to open circuit potential (+155 mV) to +300 mV. We compared the tunability of the mixed surfaces to bare Au surfaces, voltage inert surfaces, and switchable biotinylated surfaces. Our results indicate that quartz crystal microbalance allows real-time changes in analyte binding behavior, which enabled observing the evolution of neutravidin sensitivity as the applied voltage was shifted. EQCM could in principle be used in kinetic studies or to optimize voltage-switchable surfaces in adsorption-based diagnostics.

Electrically Stable Self-Assembled Monolayers Achieved through Repeated Surface Exchange of Molecules

Electrically Stable Self-Assembled Monolayers Achieved through Repeated Surface Exchange of Molecules

Use of tyrosinase nanobiosensor for detection of atrazine and simazine and its application in real water samples

ABSTRACT This study presents the development and characterization of cantilever nanobiosensors functionalized with the tyrosinase enzyme (0.05–0.001%) for the detection of atrazine and simazine in water. The optimization of tyrosinase activity through precise immobilization and sensitive layer adjustments was evaluated. Topographical analysis revealed the successful immobilization of the tyrosinase enzyme using the self-assembled monolayer technique, enhancing sensor sensitivity. Upon comparing the enzyme concentrations, it was found that the 0.006% exhibited remarkable results, including a limit of detection (LOD = 0.0080 ppb) and a limit of quantification (LOQ = 0.0267 ppb), along with enhanced storage stability for 15 days for atrazine detection. For simazine, the nanobiosensor exhibited high sensitivity (8.1532 nm/ppb) and LOD (0.0117 ppb). They demonstrated excellent reversibility (99%) over six cycles and selectivity against interfering pesticides commonly found in agricultural environments, indicating their suitability for complex sample matrices. Real water samples met regulatory standards for atrazine levels, further validating the efficacy of the nanobiosensors in detecting pesticide contamination. The enzymatic nanobiosensor achieved recoveries ranging from 97 to 101%, indicating high reproducibility. These findings demonstrate the potential of the developed nanobiosensors for sensitive and reliable pesticide detection in environmental monitoring, with implications for future applications.

Electron-Beam-Induced Modification of N-Heterocyclic Carbenes: Carbon Nanomembrane Formation.

Electron irradiation of self-assembled monolayers (SAMs) is a versatile tool for lithographic methods and the formation of new 2D materials such as carbon nanomembranes (CNMs). While the interaction between the electron beam and standard thiolate SAMs has been well studied, the effect of electron irradiation for chemically and thermally ultrastable N-heterocyclic carbenes (NHCs) remains unknown. Here we analyze electron irradiation of NHC SAMs featuring different numbers of benzene moieties and different sizes of the nitrogen side groups to modify their structure. Our results provide design rules to optimize NHC SAMs for effective electron-beam modification that includes the formation of sulfur-free CNMs, which are more suitable for ultrafiltration applications. Considering that NHC monolayers exhibit up to 100 times higher stability of their bonding with the metal substrate toward electron-irradiation compared to standard SAMs, they offer a new alternative for chemical lithography where structural modification of SAMs should be limited to the functional group.

Novel mixed self-assembled monolayers of L-cysteine and methanol on gold surfaces under ambient conditions.

In this work, we carried out an experimental and theoretical study on the formation of self-assembled monolayers of L-cysteine molecules on gold surfaces in the presence of methanol as a solvent. We report for the first time L-cysteine and methanol ordered structures forming a mixed self-assembled mono-layer on Au(100) surfaces under ambient conditions. Finger-like ordered structures with a relative height of 0.10-0.20 nm, average width of 2.0 nm and variable lengths were observed using scanning tunneling microscopy under room temperature and ambient pressure conditions. Using X-ray photoemission spectroscopy, it was determined that L-cysteine molecules bind to the gold surface through the sulfur atom of their thiol group in two molecular configurations: neutral and zwitterionic. We found that the finger-like structures are the result of complex interactions of L-cysteine molecules with gold surfaces and L-cysteine molecules with methanol molecules and among all three components of the system (L-cysteine + methanol + gold surfaces). These interactions were detected through attenuated total reflectance-Fourier transform infrared spectroscopy. Furthermore, adsorbate/substrate interactions were studied by employing ab initio calculations using density functional theory, resulting in molecular arrangements formed by chains of L-cysteine pairs surrounded by physisorbed methanol molecules.

Determining the stopping power of low kinetic energy Ne+ projectiles in self-Assembled monolayers

Neutral impact collision ion scattering spectroscopy (NICISS) is used to measure the energy loss in organic self-assembled monolayers (SAMs) on Au using Ne+ with low kinetic energies from 3 to 5 keV. With increasing film thickness, the energy loss of the projectiles increases because the projectile experiences more collisions with target atoms.Through comparing Monte-Carlo simulations with the NICISS experiments, it was found that contributions from nuclear stopping for Ne+ were significantly larger than for He+ mainly due to the stronger contribution of small-angle scattering of Ne+ making Ne NICISS unsuitable for depth profiling at energies of 5 keV or lower. The measured Ne+ electronic stopping in SAMs is small despite the large atomic number of Ne. Comparing experiments and DFT calculations shows that the latter accurately reproduce stopping powers for Ne+, while SRIM overestimates the stopping power. This contrasts He+ ions, where DFT and SRIM align closely with experiments.

Rapid Identification of Drug Mechanisms with Deep Learning-Based Multichannel Surface-Enhanced Raman Spectroscopy.

Rapid identification of drug mechanisms is vital to the development and effective use of chemotherapeutics. Herein, we develop a multichannel surface-enhanced Raman scattering (SERS) sensor array and apply deep learning approaches to realize the rapid identification of the mechanisms of various chemotherapeutic drugs. By implementing a series of self-assembled monolayers (SAMs) with varied molecular characteristics to promote heterogeneous physicochemical interactions at the interfaces, the sensor can generate diversified SERS signatures for directly high-dimensionality fingerprinting drug-induced molecular changes in cells. We further train the convolutional neural network model on the multidimensional SAM-modulated SERS data set and achieve a discriminatory accuracy toward 99%. We expect that such a platform will contribute to expanding the toolbox for drug screening and characterization and facilitate the drug development process.

Electrochemical Charge Transfer Kinetics of Ferrocene in the Light of Different Working Electrodes.

Ferrocene is an accidentally discovered organometallic compound that serves as a crucial redox probe in investigating electrochemical charge transfer dynamics. Besides solution phase studies, ferrocene derivatives are well-explored in molecular thin films, including self-assembled monolayers on various electrodes for understanding on-surface redox behavior, molecular electronics, and charge storage applications. Heterogeneous charge transfer is an imperative parameter for efficient charge transport in spin-dependent electrochemistry, photoelectrochemistry, and molecular electronic devices. In this work, we aim to study the electrochemical charge transfer of ferrocene on various electrodes such as commercially obtained glassy carbon, graphite rod, indium tin oxide (ITO), and as-prepared gold, and nickel to determine the impact of the nature of the working electrode on the electron transfer rate, diffusion coefficient, and reversibility of the redox process. Both the direct current and alternating current-based electrochemical experiments are performed, followed by digitization of the experimental results. The kinetics of electron transfer and electrochemical reversibility reveal a strong dependence on the nature of the working electrode, as the electrochemically driven oxidation and reduction of the material of interest are directly related to the Fermi energy and electronic structure of the working electrode.

Functional Materials of 2D Self-Assembled Nanoparticle Monolayers: Preparation and Application

Functional Materials of 2D Self-Assembled Nanoparticle Monolayers: Preparation and Application

Bio-inspired Cu2O cathode for O2 capturing and oxidation boosting in electro-Fenton for sulfathiazole decay

A hydrophobic Cu2O cathode (CuxO-L) was designed to solve the challenge of low oxidation ability in electro-Fenton (EF) for treating emerging pollutants. This fabrication process involved forming Cu(OH)2 nanorods by oxidizing copper foam (Cu-F) with (NH4)2S2O8, followed by coating them with glucose via hydrothermal treatment. Finally, a self-assembled monolayer of 1-octadecanethiol was introduced to create a low-surface-energy, functionalized CuxO-L cathode. Results exhibited an approximately 7.9-fold increase in hydroxyl radical (·OH) generation compared to the initial Cu-F. This enhancement was attributed to two key factors: (Ⅰ) the superior O2-capturing ability of CuxO-L cathode, which led to high H2O2 production due to a 2 nm thick hydrophobic gas layer facilitated O2-capturing; (Ⅱ) a relative high concentration of Cu+ at the CuxO-L cathode promoted the activation of H2O2 into·OH. In addition, the performance of EF with the CuxO-L cathode using sulfathiazole (STZ) as a model pollutant was evaluated. This study offers valuable insights into the design of O2-capturing cathodes in EF processes, particularly for treating emerging organic pollutants.

Over-Time Stability Evaluation of Fluorinated Self-Assembled Monolayer on Commercial Indium Tin Oxide Electrode on PET Substrate

Motivation: Self-Assembled Monolayer (SAM) modified electrode has a key role in electrochemical biosensor applications to achieve desired sensing properties such as selective interaction with target protein and anti-fouling properties of non-specific protein. However, the degradation of SAM layer on the electrode can cause the electrochemical response to drift over time. This causes adversary effect on the designed biosensor such as limited shelf life and inconsistent electrochemical signal reading between electrodes. For that matter, it is important to understand the signal drift behaviour and ultimately obtain a SAM-modified electrode with good stability over time. In this study, we observed the signal drift of SAM-modified indium tin oxide electrode on PET substrate (ITO-PET). Three-electrode electrochemical impedance spectroscopy (EIS) measurement was carried to evaluate the electrochemical properties of the ITO-PET substrate over time. Materials and Methods: Commercial ITO-PET (Adafruit, NY, USA) was used as electrode and was modified using Perfluoro-octyltriethoxysilane (Sigma Aldrich, St. Louis, MO, USA) self-assembled monolayer. The ITO-PET substrate was modified by using room temperature RCA-1 silanization process as shown in Figure 1. The modified electrode was rinsed in ethanol and DI water and stored in dark condition with temperature of 5oC. The Electrochemical Impedance Spectroscopy measurements were carried by using Solartron SI1260 impedance analyser tandem with SI1287 potentiostat. with saturated KCl Ag/AgCl (RRPEAGCL2, Pine Research, NC, USA) electrode and Pt wire counter electrode (MW-1032; BASi, West Lafayette, IN, USA). Potassium Ferricyanide (K3Fe(CN)6) (Fischer Scientific, Fair Lawn, NJ, USA) with concentration of 10 mM in 1x PBS was used as redox probe. The EIS run was set at 0.31 Vdc and 10 mV Vac amplitude with frequency ranging from 0.1 – 10000 Hz. Results: We observed significant increase charge transfer resistance (Rct)increase of SAM-ITO sample (4498 ± 460 Ω.cm2) compared to the bare ITO sample (1348 ± 68 Ω.cm2). The signal also maintains its consistency after one week of storage in enclosed dry and dark environment at 5oC with 3% change in average Rct value (133 Ω.cm2). Ongoing work in this study includes the electrochemical signal evaluation of the ITO-SAM electrode exposed to protein such as casein and BSA. Figure 1

In-Situ Investigation of Surface Modifiers Dithiocarbamates on Au Electrodes for Electrochemical CO2 Reduction

Molecular functionalization of metal electrodes via self-assembled monolayers (SAMs) can introduce synthetically tunable properties to metal surfaces and has exhibited great potential in electrocatalysis. Alkanethiols are commonly used organic ligands because of their strong affinity to Au but they are prone to desorption at negative potentials. Alternatively, dithiocarbamates (DTC) show superior electrochemical stability. In this study, a series of DTCs, differing in hydrophobicity, size, and steric bulk, were synthesized to prepare SAM-functionalized Au electrodes. The properties of the resulting surfaces (e.g. wettability, surface coverage, and reductive stability) were investigated by analytical and electrochemical techniques. Particularly, in-situ approaches such as surface-enhanced infrared absorption spectroscopy (SEIRAS) are employed to characterize the molecularly modified interface. The novel catalyst platforms were explored for electrochemical CO2 reduction.

A Zwitterionic Anti-Fouling Coating Promotes Electrochemical Biosensing in Complex Media

Biofoulants present in complex media, such as blood, plasma, saliva, etc., can cause an increase in the background of the signal or a reduction in signal-to-noise ratio, due to which most biosensors require a sample processing step. One of the major interactions for biofouling in biosensing platforms is non-specific hydrophobic interactions, which can be prevented using hydrophilic polymeric coatings [1], [2]. However, most hydrophilic polymers are not conductive enough to provide a strong electrochemical current signal, whereas the existing conductive polymers are often hydrophobic. To avoid this, zwitterionic polymers that are both ionically conductive [3] and hydrophilic [3] can be used as anti-fouling polymers for electrochemical biosensing. Additionally, these polymers are highly effective at preventing fouling by electrostatically-induced water structuring [4]. Herein, we report a zwitterionic polymer (bearing thiols, aldehydes and carboxylic acid groups) that forms a thin conductive and hydrophilic layer on the electrodes, while also housing biorecognition layers for capturing target analytes of interest.The polymer was synthesized by free radical copolymerization and coated on gold electrodes to form a thin coating (16 nm when dry), which upon hydration results in a hydrophilic interface (contact angle <15 degrees). Anti-fouling properties were validated by determining the adsorption of radiolabeled human serum albumin (HSA) protein (spiked in plasma) on polymer-coated electrodes. The polymer-coated electrodes showed a ~67% reduction in protein adsorption relative to bare gold electrodes. Additionally, no significant change in anodic current was observed when 1% HSA was incubated on polymer-coated electrodes for 1 hour; whereas an 83% decrease in anodic current was observed on bare-gold electrodes under the same conditions. The polymer-modified electrode was used in detecting redox-labeled DNA sequences with a LOD of 11 nM in buffer and unprocessed plasma. The coating was also utilized to detect COVID-19, where the prepared setup detected 104 cp/mL of SARS-CoV-2 pseudovirus spiked in 50% unprocessed saliva. Similar coatings created from poly(ethylene glycol) (PEG) were unresponsive toward SARS-CoV-2 spiked in 50% saliva [5]. The anti-fouling polymer coatings developed herein show enhanced performance compared to previously reported strategies, based on self-assembled monolayers, in detecting target analytes in complex media, demonstrating the potential for use in clinical diagnostics.

Nanobiosensors based on tyrosinase with alkanethiols for detection commercial formulation of atrazine in artesian water samples applied in agriculture crop

This study aims to develop cantilever nanobiosensors functionalized with commercial tyrosinase enzymes and alkanethiols for the detection of a commercial formulation of atrazine in artesian water samples used in agricultural crops. Functionalization was carried out using the self-assembled monolayer (SAM) technique with different alkanethiols, namely, 16-mercaptohexadecanoic acid (16-MHDA) and 11-mercaptoundecanoic acid (11-MUA), in conjunction with commercial tyrosinase enzymes. Surface characterization techniques confirm the successful deposition of the sensing layer. The nanobiosensors exhibited the capability to detect various concentrations of atrazine in water, achieving high sensitivity with detection and quantification limits in the µg/L range, while maintaining 100 % reversibility. The enzyme retained 87 % and 80 % of its activity when immobilized on 16-MHDA and 11-MUA linkages, respectively. The response of cantilever nanobiosensors was stable after 13 min, with deflection values showing a direct proportional relationship with atrazine concentrations ranging from 0.001 to 100 µg/L. Both cantilever nanobiosensors demonstrated promising responses, with 11-MUA differing statistically (P<0.05) from 16-MHDA. The rapid detection of commercial atrazine was successfully conducted in real water samples collected directly during its application in crop fields. Consequently, the developed devices hold significant potential for practical use in the detection of atrazine in water, contributing to assessments of environmental quality.

( General Student Poster Award Winner, 2nd Place) Template-Assisted Fabrication of Transparent SERS Sensor with Uniform Au-Ag Nanoparticle Electrodeposition

Surface-enhanced Raman spectroscopy (SERS) is a very powerful tool for analyzing molecular interactions and provides unique spectral fingerprint information about chemical bondings.[1] SERS enhances weak Raman scattering signals through surface-localized plasmon resonance (LSPR) of the plasmonic metal nanoparticles. Arbitrarily distribution of plasmonic metal nanoparticles can result in a non-uniform SERS enhancement effect (EF) and low reproducibility, which hinders the practical application of this ultra-sensitive analysis technology.[2] The development of a cost-effective, highly reliable, and highly reproducible SERS sensor with precisely controlled nanoparticle size and distribution is still a challenge.[3] Electron beam lithography (EBL) is commonly used to achieve well-controlled nanoscale patterns, which can be used as a top-down SERS sensor fabrication technique.[2] However, the time-consuming and extremely costly method makes the SERS sensor not easily accessible.In this research, we propose a template-assisted fabrication process by electrodepositing nanoparticles into nanoarrays on a transparent ITO surface. This method precisely controls the surface morphology and provides high reproducibility without relying on EBL techniques. For the fabrication process, first, a layer of sol-gel SiO2 solution was spin-coated onto the ITO surface, and an array of nano-pillars was used to imprint the nanopattern to the sol-gel solution layer, to realize the nano-ordered uniformly distributed nanoarrays. (Fig.1) For the plasmonic material, Au-Ag alloy was deposited into the nanoarray due to its high durability and high SERS EF.[4] The use of a pulse current deposition, additives, and self-assembled monolayer (SAM) was also discussed from the perspective of altering the surface property of the ITO surface, to achieve dense and smooth filling of deposits in the nanoarray. The SERS sensor fabricated was tested with Janus Green B (JGB) and demonstrated a good SERS EF and good signal uniformity. We believe this sensor is widely applicable for different systems, further optimization and application of this sensor can bring us one step closer to the quantitative analysis by SERS. The fabricated sensor should be especially useful in electrochemical reaction analysis and biomolecular sensing.[1] Fleishmann et al., Phys. Lett., 26, 163(1974)[2] Lee et al., Chemical Society reviews., 48, 731(2019)[3] Shi et al., 66, 6525(2018)[4] B. Liu et al., 55 , 117104(2016) Figure 1

Interactions of Alkali Ions and Phospholipid Monolayers at Organic-Water Interfaces

The self-assembled phospholipids monolayers at interfaces between two immiscible electrolyte solutions (ITIES) are commonly used to study the interactions between cell membranes and species passing in and out through membrains such as ions, drugs, and other nutrients. In this study, we utilized electrochemical techniques such as open circuit potential (OCP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) to study the pure phospholipd monolayer formed by 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) and its mixture with 1,2-dioleoyl-sn-glycero-3-phospho-(1'-racglycerol) (sodium salt) (DOPG) at 1,2-dichloroethane-water interfaces. Our study has shown that at higher applied electric potentials, there seems to be no change in the facilitation of cation transfers by DOPC/DOPG monolayer compared to DOPC monolayer. However, at lower applied potentials, the DOPGs in the mixed monolayer seemed to leave the interface under the influence of the applied electric field, indicated by both the higher capacitance obtained throught the EIS measurements and the higher currents from the CV measurements compared to results obtained from the sample consisted of the pure DOPC monolayer. Furthermore, our study also showed a general rise in capacitance when incorporating heavier alkali ions in the aqueous phase for the sample with the mixture of DOPC/DOPG at higher applied electric potentials.

Antimicrobial Peptide-Based Sensor for the Electrochemical Detection of Methicillin-Resistant Staphylococcus Aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a gram-positive bacterium that colonizes on the skin and nasal track of humans, which can lead to serious illnesses such as skin and soft tissue infections, pneumonia, and septicemia.MRSA is resistant to an entire class of antibiotics called beta-lactams, including penicillin, amoxicillin, and oxacillin, making it more difficult to treat. Culture based methods and molecular based methods like PCR are currently being used for the detection of MRSA, but these methods possess the drawbacks of being slow and expensive, respectively. Thus, we focused on developing a reagentless, cost-effective, near real-time detection method for intact MRSA cells.Antimicrobial peptides (AMPs) possess the ability to interact with bacterial cells by inhibiting their growth or by lysing them.However, this initial interaction between the cationic AMPs and the negatively charged bacterial cells can be used for the detection of pathogens like MRSA. Here, we used a MRSA-specific antimicrobial peptide, DP7, to fabricate an electrochemical peptide-based (E-PB) sensor. The DP7 probe was further modified with a methylene blue redox label and an alkanethiol chain which allows for the formation of a thiol-gold self-assembled monolayer. The sensor surface was passivated with both 6-mercapto-1-hexanol and a thiolated tetra-thymine sequence to prevent surface fouling. Electrochemical detection of MRSA was accomplished using alternating current voltammetry. Control experiments were performed using two gram-positive bacteria, Bacillus subtilis and Staphylococcus epidermidis, and two gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa. The DP7 sensor responded to MRSA in a concentration-dependent manner and was proven to be selective for MRSA over the other four microbes. Specifically, the % signal suppression obtained for MRSA was much larger when compared to those obtained for the other microbes. The same behavior was observed in pure buffer and 5% synthetic wound fluid. In addition, the detection time was relatively short, with signal saturation in less than 60 min. Overall, the DP7 sensor has demonstrated to possess attributes similar to other E-PB sensors. It has the potential to be developed as a rapid, reliable, and cost-effective diagnostic tool for MRSA, which will be useful in preventing the spread of the pathogen in the community. Furthermore, this sensing platform is versatile and can be redesigned for detection of other pathogenic bacteria.

On-Surface Photopolymerization - What Does the Surface Do?

We attained the synthesis of mesoscale-ordered 2D polymers by the topochemical on-surface photopolymerization of fluorinated anthracene triptycene (fantrip) monomers. The underlying protocol is two-staged: (1) Self-assembly of the monomers into a photopolymerizable monolayer structure, where the photoactive anthracene moieties are face-to-face stacked; (2) cross-linking of the self-assembled monolayer into a covalent 2D polymer by photochemically excited [4+4] cycloadditions between the antiparallel aligned anthracene blades. Thereby, the long-range order attained in step (1) is transferred into the covalent state.Yet, the topochemical approach depends crucially on achieving the reactive monomer packing with the appropriate mutual alignment of the anthracene blades. For this initial self-assembly, the underlying surface plays a decisive role, which also extends to the photopolymerization.We show that the photoactive monolayer packing of fantrip monomers can be achieved on both alkane-passivated graphite and iodine-passivated Au(111) or Ag(111). Although the fantrip self-assembly appears essentially similar on these substrates, there are distinct differences in the subsequent photopolymerization. These can be rationalized by the photoexcitation of the substrate and the subsequent transfer of hot carriers to the molecular networks.Nat. Chem. 13, 730-736 (2021)Eur. J. Org. Chem. 2021, 5478–5490 (2021)Trends Chem. 4, 471-474 (2022)Angew. Chem. Int. Ed. 61, e202201044 (2022)