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Interface engineering is pivotal for enhancing the performance and stability of devices with layered structures, including solar cells, electronic devices, and electrochemical systems. Incorporating the interfacial dipole between the bulk layers effectively modulates the energy level difference at the interface and does not significantly influence adjacent layers overall. However, interfaces can drastically affect adjoining layers in ultrathin devices, which are essential for next-generation electronics with high integrity, excellent performance, and low power consumption. In particular, the interfacial effect is pronounced in ultrathin semiconductors, which have a weak electric field screening effect. Herein, the substantial interfacial impact on the ultrathin silicon is shown, the p- to n-type inversion of the semiconductor solely through the deposition of a self-assembled monolayer (SAM) without external bias. The effects of SAMs with different interfacial dipoles are investigated by using Hall measurement and surface analytic techniques, such as UPS, XPS, and KPFM. Furthermore, the lateral electronic junction of the ultrathin silicon is engineered by the regioselective deposition of SAMs with opposite dipoles, and the device exhibits rectification behavior. When the interfacial dipole of SAM is manipulated, the rectification ratio changes sensitively, and thus the fabricated diode shows potential to be developed as a sensing platform.

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Perovskite solar cells have been proven to enhance cell characteristics by introducing passivation materials that suppress defect formation. Defect states between the electron transport layer and the absorption layer reduce electron extraction and carrier transport capabilities, leading to a significant decline in device performance and stability, as well as an increased probability of non-radiative recombination. This study proposes the use of an amino acid (L-Histidine) self-assembled monolayer material between the transport layer and the perovskite absorption layer. Surface analysis revealed that the introduction of L-Histidine improved both the uniformity and roughness of the perovskite film surface. X-ray photoelectron spectroscopic analysis showed a reduction in oxygen vacancies in the lattice and an increase in Ti4+, indicating that L-Histidine successfully passivated trap states at the perovskite and TiO2 electron transport layer interface. In terms of device performance, the introduction of L-Histidine significantly improved the fill factor (FF) because the reduction in interface defects could suppress charge accumulation and reduce device hysteresis. The FF of large-area solar modules (25 cm2) with L-Histidine increased from 55% to 73%, and the power conversion efficiency (PCE) reached 16.5%. After 500 h of aging tests, the PCE still maintained 91% of its original efficiency. This study demonstrates the significant impact of L-Histidine on transport properties and showcases its potential for application in the development of large-area perovskite module processes.

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Hybrid strategies that combine conventional top-down lithography with bottom-up molecular assembly are of interest for a range of applications including nanolithography and sensors. Interest in these strategies stems from the ability to create complex architectures over large areas with molecular-scale control and precision. The molecular-ruler process typifies this approach where the sequential layer-by-layer assembly of mercaptoalkanoic acid molecules and metal ions are combined with conventional top-down lithography to create precise, registered nanogaps. However, the quality of the metal-ligated mercaptoalkanoic acid multilayer is a critical characteristic in generating reproducible and robust nanoscale structures via the molecular-ruler process. Therefore, we explore the assembly of alkanethiolate monolayers, mercaptohexadecanoic acid (MHDA) monolayers, and Cu-ligated MHDA multilayers on Au{111} substrates using atomic force microscopy and in situ dynamic spectroscopic ellipsometry. The chemical film thicknesses in situ dynamic spectroscopic ellipsometry agree with previous ex situ surface analytical methods. Moreover, in situ dynamic spectroscopic ellipsometry provides insight into the assembly process without interrupting the assembly process and potentially altering the characteristics of the resulting chemical film. By following the real-time dynamics of each deposition step, the assembly of the Cu-ligated MHDA multilayers can be optimized to minimize deposition time while having minimal impact to the quality of the chemical film.

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In this study, a thin poly (methyl methacrylate) coating was formed on a self-assembled monolayer formed on a gold plate after chemically binding estrone. Subsequently, the estrone molecules were hydrolyzed and extracted using a solvent to form a molecular-imprinted system. The estrone-imprinted gold plate was then used as a working electrode to measure the estrone recognition ability through electrochemical methods. The recognition ability of this working electrode was evaluated for similar compounds. The selectivity factors for the seven estrone analogs were measured, and these values ranged from 0.19 to 0.67. According to the experimental results, the estrone-imprinted system showed good differentiation of estrone from other estrone analogs. Comparing these selectivity factors with those of a previous study on a cholesterol-imprinted system, the relative molecular size difference between the target molecule and similar molecules had a significant impact on the selectivity factor.

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Perovskite photodetectors, devices that convert light to electricity, require good extraction and low noise levels to maximize the signal-to-noise ratio. Self-assembling monolayers (SAMs) have been shown to be effective hole transport materials thanks to their atomic layer thickness, transparency, and energetic alignment with the valence band of the perovskite. While efforts are being made to reduce noise levels via the active layer, little has been done to reduce noise via SAM interfacial engineering. Herein, we report hybrid perovskite photodetectors with high detectivity by blending two different SAMs (2-PACz and Me-4PACz). We find that with a 1:1 2-PACz:Me-4PACz ratio (by weight), the devices achieved a low noise of 1 × 10-13 A Hz-1/2, a high responsivity of 0.41 A W-1 at 710 nm, and a specific detectivity of 6.4 × 1011 Jones at 710 nm at -0.5 V, outperforming its two counterparts. In addition to the improved noise levels in these devices, impedance spectroscopy revealed that higher recombination lifetimes of 0.85 µs were achieved for the 1:1 2-PACz:Me-4PACz-based photodetectors, confirming their low defect density.

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Area selective deposition (ASD) is a promising IC fabrication technique to address misalignment issues arising in a top-down litho-etch patterning approach. ASD can enable resist tone inversion and bottom-up metallization, such as via prefill. It is achieved by promoting selective growth in the growth area (GA) while passivating the non-growth area (NGA). Nevertheless, preventing undesired particles and defect growth on the NGA is still a hurdle. This work shows the selectivity of Ru films by passivating the Si oxide NGA with self-assembled monolayers (SAMs) and small molecule inhibitors (SMIs). Ru films are deposited on the TiN GA using a metal-organic precursor tricarbonyl (trimethylenemethane) ruthenium (Ru TMM(CO)3) and O2 as a co-reactant by atomic layer deposition (ALD). This produces smooth Ru films (<0.1 nm RMS roughness) with a growth per cycle (GPC) of 1.6 Å/cycle. Minimizing the oxygen co-reactant dose is necessary to improve the ASD process selectivity due to the limited stability of the organic molecule and high reactivity of the ALD precursor, still allowing a Ru GPC of 0.95 Å/cycle. This work sheds light on Ru defect generation mechanisms on passivated areas from the detailed analysis of particle growth, coverage, and density as a function of ALD cycles. Finally, an optimized ASD of Ru is demonstrated on TiN/SiO2 3D patterned structures using dimethyl amino trimethyl silane (DMA-TMS) as SMI.

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Lately, carbazole-based self-assembled monolayers (SAMs) are widely employed as effective hole-selective layers (HSLs) in inverted perovskite solar cells (PSCs). Nevertheless, these SAMs tend to aggregate in solvents due to their amphiphilic nature, hindering the formation of a monolayer on the ITO substrate and impeding effective passivation of deep defects in the perovskites. In this study, a series of new SAMs including DPA-B-PY, CBZ-B-PY, POZ-B-PY, POZ-PY, POZ-T-PY, and POZ-BT-PY are synthesized, which are employed as interfacial repairers and coated atop CNph SAM to form a robust CNph SAM@pseudo-planar monolayer as HSL in efficient inverted PSCs. The CNph SAM@pseudo-planar monolayer strategy enables a well-aligned interface with perovskites, synergistically promoting perovskite crystal growth, improving charge extraction/transport, and minimizing nonradiative interfacial recombination loss. As a result, the POZ-BT-PY-modified PSC realizes an impressively enhanced solar efficiency of up to 24.45% together with a fill factor of 82.63%. Furthermore, a wide bandgap PSC achieving over 19% efficiency. Upon treatment with the CNph SAM@pseudo-planar monolayer, also demonstrates a non-fullerene organic photovoltaics (OPVs) based on the PM6:BTP-eC9 blend, which achieves an efficiency of 17.07%. Importantly, these modified PSCs and OPVs all show remarkably improved stability under various testing conditions compared to their control counterparts.

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Self-assembled monolayers (SAMs) as the hole-selective contact have achieved remarkable success in iodine-based perovskite solar cells (PSCs), while their impact on bromine-based PSCs is limited due to the poor perovskite crystallization behavior and mismatched energy level alignment. Here, a highly efficient SAM of (2-(3,6-diiodo-9H-carbazol-9-yl)ethyl)phosphonic acid (I-2PACz) is employed to address these challenges in FAPbBr3-based PSCs. The incorporation of I atoms into I-2PACz not only releases tensile stress within FAPbBr3 perovskite, promoting oriented crystallization and minimizing defects through halogen-halogen bond, but also optimizes the energy levels alignment at hole-selective interface for enhanced hole extraction. Ultimately, a power conversion efficiency (PCE) of 11.14% is achieved, which stands among the highest reported value for FAPbBr3 PSCs. Furthermore, the semitransparent devices/modules exhibit impressive PCEs of 8.19% and 6.23% with average visible transmittance of 41.98% and 38.99%. Remarkably, after operating at maximum power point for 1000 h, the encapsulated device maintains 93% of its initial PCE. These results demonstrate an effective strategy for achieving high-performance bromine-based PSCs toward further applications.

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Perfluorododecyl iodide (I-PFC12) is of interest for area-selective deposition (ASD) applications as it exhibits intriguing properties such as ultralow surface energy, the ability to modify silicon's band gap, low surface friction, and suitability for micro-contact patterning. Traditional photolithography is struggling to reach the required critical dimensions. This study investigates the potential of using I-PFC12 as a way to produce contrast between the growth area and non-growth areas of a surface subsequent to extreme ultraviolet (EUV) exposure. Once exposed to EUV, the I-PFC12 molecule should degrade with the help of the photocatalytic substrate, allowing for the subsequent selective deposition of the hard mask. The stability of a vapor-deposited I-PFC12 self-assembled monolayer (SAM) was examined when exposed to ambient light for extended periods of time by using X-ray photoelectron spectroscopy (XPS). Two substrates, SiO2 and TiO2, are investigated to ascertain the suitability of using TiO2 as a photocatalytic active substrate. Following one month of exposure to light, the atomic concentrations showed a more substantial fluorine loss of 10.2% on the TiO2 in comparison to a 6.2% loss on the SiO2 substrate. This more pronounced defluorination seen on the TiO2 is attributed to its photocatalytic nature. Interestingly, different routes to degradation were observed for each substrate. Reference samples preserved in dark conditions with no light exposure for up to three months show little degradation on the SiO2 substrate, while no change is observed on the TiO2 substrate. The results reveal that the I-PFC12 SAM is an ideal candidate for resistless EUV lithography.

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2D materials (2DMs), known for their atomically ultrathin structure, exhibit remarkable electrical and optical properties. Similarly, molecular self-assembled monolayers (SAMs) with comparable atomic thickness show an abundance of designable structures and properties. The strategy of constructing electronic devices through unique heterostructures formed by van der Waals assembly between 2DMs and molecular SAMs not only enables device miniaturization, but also allows for convenient adjustment of their structures and functions. In this review, the fundamental structures and fabrication methods of three different types of electronic devices dominated by 2DM-SAM heterojunctions with varying architectures are timely elaborated. Based on these heterojunctions, their fundamental functionalities and characteristics, as well as the regulation of their performance by external stimuli, are further discussed.

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Extracellular vesicles (EVs) are preeminent carriers of biomarkers and have become the subject of intense biomedical research for medical diagnostics using biosensors. To create effective EV-based immunoassays, it is imperative to develop surface chemistry approaches with optimal EV detection targeting transmembrane protein biomarkers that are not affected by cell-to-cell variability. Here, we developed a series of immunoassays for the detection of EVs derived from mouse monocyte cells using surface plasmon resonance (SPR) biosensors. We chemically immobilized antibodies onto mixed self-assembled monolayers of oligo ethylene glycol (OEG) alkanethiolates with carboxylic and hydroxylic terminal groups. The effects of antibody clonality (monoclonal vs polyclonal) and antibody surface coverage in targeting EVs via CD81 tetraspanins were investigated. We determined binding kinetic parameters, establishing trends from steric hindrance effects and epitope recognition properties of antibodies. Our results indicate that a 40% surface coverage of polyclonal antibodies covalently linked onto a mixed SAM with 10% of terminated -COOH groups yields a promising approach for EV detection with a linear range of 1.9 × 108-1.9 × 109 EVs/mL and a limit of detection of 5.9 × 106 EVs/mL. This optimal immunoassay exhibits a 1.92 nM equilibrium dissociation constant for bound EVs, suggesting a high binding affinity when CD81 is targeted. Our study provides important insights into surface chemistry development for EV detection targeted via transmembrane protein biomarkers using antibodies, which has promising applications for disease diagnostics.

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Two-dimensional materials hold great potentials for beyond-CMOS (complementary metal-oxide-semiconductor) electronical and optoelectrical applications, and the development of field effect transistors (FET) with excellent performance using such materials is of particular interest. How to improve the performance of devices thus becomes an urgent issue. The performance of FETs depends greatly on the intrinsic electrical properties of the channel materials, meanwhile the device interface quality, such as extrinsic scattering of charged impurities, charge traps, and substrate surface roughness have a great influence on the performance. In this paper, the impact of the interface quality on the carrier diffusion behaviors of monolayer (ML) MoSe2 has been investigated by using an in situ ultrafast laser technique to avoid the surface contamination during device fabrication process. Two types of self-assembled monolayers (SAMs) are introduced to modify the gate dielectric surface through an interface engineering approach to obtain chemical-stable interfaces. The results showed that the transport properties of ML MoSe2 were enhanced after interface engineering, for example, the carrier mobility of ML MoSe2 was improved from ∼59.4 to ∼166.5 cm2 V-1 s-1 after the SAM modification. Meanwhile, the photocarrier dynamics of ML MoSe2 before and after interfacial engineering were also carefully studied. Our studies provide a feasible method for improving the carrier diffusion behaviors of such materials, and making them suited for application in future integrated circuit.

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In the fabrication of inverted perovskite solar cells (PSCs), the wettability, adsorbability, and compactness of self-assembled monolayers (SAMs) on conductive substrates have critical impacts on the quality of the perovskite films and the defects at the buried perovskite-substrate interface, which control the efficiency and stability of the devices. Herein, three bisphosphonate-anchored indolocarbazole (IDCz)-derived SAMs, IDCz-1, IDCz-2, and IDCz-3, are designed and synthesized by modulating the position of the two nitrogen atoms of the IDCz unit to improve the molecular dipole moments and strengthen the π-π interactions. Regulating the work functions (WF) of FTO electrodes through molecular dipole moments and energy levels, the perovskite band bends upwards with a small offset for ITO/IDCz-3/perovskite, thereby promoting hole extraction and blocking electrons. As a result, the inverted PSC employing IDCz-3 as hole-collecting layer exhibits a champion PCE of 25.15%, which is a record efficiency for the multipodal SAMs-based PSCs. Moreover, the unencapsulated device with IDCz-3 can be stored for at least 1800 h with little degradation in performance.

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The formation of a stable solid electrolyte interphase (SEI) layer is crucial for enhancing the safety and lifespan of Li metal batteries. Fundamentally, a homogeneous Li+ behavior by controlling the chemical reaction at the anode/electrolyte interface is the key to establishing a stable SEI layer. However, due to the highly reactive nature of Li metal anodes (LMAs), controlling the movement of Li+ at the anode/electrolyte interface remains challenging. Here, an advanced approach is proposed for coating a sacrificial layer called fluorinated self-assembled monolayer (FSL) on a boehmite-coated polyethylene (BPE) separator to form a stable SEI layer. By leveraging the strong affinity between the fluorine functional group and Li+, the rapid formation of a LiF-rich SEI layer in the cell production and early cycling stage is facilitated. This initial stable SEI formation promotes the subsequent homogeneous Li+ flux, thereby improving the LMA stability and yielding an enhanced battery lifespan. Further, the mechanism behind the stable SEI layer generation by controlling the Li+ dynamics through the FSL-treated BPE separator is comprehensively verified. Overall, this research offers significant contributions to the energy storage field by addressing challenges associated with LMAs, thus highlighting the importance of interfacial control in achieving a stable SEI layer.

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Thermal energy storage using phase change materials (PCMs) has great potential to reduce the weather dependency of sustainable energy sources. However, the low thermal conductivity of most PCMs is a long-standing bottleneck for large-scale practical applications. In modifications to increase the thermal conductivity of PCMs, the interfacial thermal resistance (ITR) between PCMs and discrete additives or porous networks reduces the effective thermal energy transport. In this work, we investigated the ITR between a metal (gold) and a polyol solid-liquid PCM (erythritol) at various temperatures including temperatures below the melting point (300 and 350 K), near the melting point (390, 400, 410 K, etc) and above the melting point (450 and 500 K) adopting non-equilibrium molecular dynamics. Since the gold-erythritol interfacial thermal conductance (ITC) is low regardless of whether erythritol is melted or not (<40 MW m-2K-1), self-assembled monolayers (SAMs) were used to boost the interfacial thermal energy transport. The SAM with carboxyl groups was found to increase the ITC most (by a factor of 7-9). As the temperature increases, the ITC significantly increases (by ∼50 MW m-2K-1) below the melting point but decreases little above the melting point. Further analysis revealed that the most obvious influencing factor is the interfacial binding energy. This work could build on existing composite PCM solutions to further improve heat transfer efficiency of energy storage applications in both liquid and solid states.

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2-(((5-mercapto-1,3,4-thiadiazol-2-yl)imino)methyl)phenol (MTP) was synthesized, self-assembled on the surface of gold (Au) electrode (Au-MTP) followed by characterization using Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS). CV and EIS confirmed the formation of well-organized Au-MTP SAM free from defects and pinholes. Au-MTP was further utilized as a platform for sensing of Hg2+ using EIS. The results showed sensitive and selective response of Au-MTP towards Hg2+ in the linear concentration range from 1.0 × 10-10 M to 1.0 × 10-4 M with limit of detection (LoD) of 5.6 × 10-11 M. Furthermore, MTP was self-assembled on gold nanoparticles (AuNPs) and MTP bound gold nanoparticles (MTP-AuNPs) so obtained were used as modifier for construction of carbon paste electrode (CPE). Hg2+-CPE exhibited Nernstian response towards Hg2+ with slope of 28.3 mV/decade in the concentration range from 1.0 × 10-5 M to 1.0 × 10-1 M with LoD of 6.3 × 10-6 M. Both the Au-MTP EIS sensor and Hg2+-CPE were successfully applied for estimation of Hg2+ content in tap water samples.

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Aqueous Zn-ion batteries (ZIBs) are promising next-generation energy storage devices, yet suffer from the issues of hydrogen evolution reaction (HER) and intricate side reactions on the Zn anode surface. The hydrogen (H)-bond networks play a critical role in interfacial proton transport that may closely relate to HER but are rarely investigated. Herein, we report a self-assembled monolayer (SAM) strategy which is constructed by anchoring ionic liquid cations on Ti3C2Tx substrate for HER-free Zn anode. Molecule dynamics simulations reveal that the rationally designed SAM with a high coordination number of water molecules (25-27, 4-6 for Zn2+) largely reduces the interfacial densities of H2O molecules, therefore breaking the connectivity of H-bond networks and blocking proton transport on the interface, by which the HER is suppressed. Then, a series of in situ characterizations demonstrate that negligible amounts of H2 gas are collected from the Zn@SAM-MXene anode. Consequently, the symmetric cell enables a long-cycling life of 3000 h at 1 mA cm-2 and 1000 h at 5 mA cm-2. More significantly, the stable Zn@SAM-MXene films are successfully used for coin full cells showing high-capacity retention of over 94 % after 1000 cycles and large-area (10×5 cm2) pouch cells with desired performance.

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The effective management of infectious diseases and the growing concern of antibiotic resistance necessitates accurate and targeted therapies, highlighting the importance of antibiotic susceptibility testing. This study aimed to develop a real-time impedimetric biosensor for identifying and monitoring bacterial growth and antibiotic susceptibility. The biosensor employed a gold 8-channel disk-shaped microelectrode array with specific antibodies as bio-recognition elements. This setup was allowed for the analysis of bacterial samples, including Staphylococcus aureus, Bacillus cereus, and Micrococcus luteus. These microorganisms were successfully cultured and detected within 1 h of incubation even with a minimal bacterial concentration of 10 CFU/ml. Overall, the developed biosensor array exhibits promising capabilities for monitoring S. aureus, B. cereus and M. luteus, showcasing an excellent linear response ranging from 10 to 104 CFU/ml with a detection limit of 0.95, 1.22 and 1.04 CFU/mL respectively. Moreover, real-time monitoring of antibiotic susceptibility was facilitated by changes in capacitance, which dropped when bacteria were exposed to antibiotic doses higher than their minimum inhibitory concentration (MIC), indicating suppressed bacterial growth. The capacitance measurements enabled determination of half-maximal cytotoxic concentrations (CC50) values for each bacteria-antibiotic pair. As a proof-of-concept application, the developed sensor array was employed as a sensing platform for the real time detection of bacteria in milk samples, which ensured the reliability of the sensor for in-field detection of foodborne pathogens and rapid antimicrobial susceptibility tests (ASTs).

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Interfacial layers (ILs) are prerequisites to form the selective charge transport for high-performance organic photovoltaics (OPVs) but mostly result in considerable parasitic absorption loss. Trimming the ILs down to a mono-molecular level via the self-assembled monolayer is an effective strategy to mitigate parasitic absorption loss. However, such a strategy suffers from inferior electrical contact with low surface coverage on rough surfaces and poor producibility. To address these issues, here, the self-assembled interlayer (SAI) strategy is developed, which involves a thin layer of 2-6 nm to form a full coverage on the substrate via both covalent and van der Waals bonds by using a self-assembled molecule of 2-(9H-carbazol-9-yl) (2PACz). Via the facile spin coating without further rinsing and annealing process, it not only optimizes the electrical and optical properties of OPVs, which enables a world-record efficiency of 20.17% (19.79% certified) but also simplifies the tedious processing procedure. Moreover, the SAI strategy is especially useful in improving the absorbing selectivity for semi-transparent OPVs, which enables a record light utilization efficiency of 5.34%. This work provides an effective strategy of SAI to optimize the optical and electrical properties of OPVs for high-performance and solar window applications.

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Nanostructuring of gold surfaces to enhance electroactive surface area has proven to significantly enhance the performance of electrochemical aptamer-based (E-AB) sensors, particularly for electrodes on the microscale. Unlike for sensors fabricated on polished gold surfaces, predicting the behavior of E-AB sensors on surfaces with varied gold morphologies becomes more intricate due to the effects of surface roughness and the shapes and sizes of surface features on supporting a self-assembled monolayer. In this study, we explored the impact of gold morphology characteristics on sensor performance, evaluating parameters such as signal change in response to the addition of the target analyte, aptamer probe packing density, and continuous sensing ability. Our findings reveal that surface area enhancement can either enhance or diminish sensor performance for gold nanostructured E-AB sensors, contingent upon the surface morphology. In particular, our results indicate that the aptamer packing density and target analyte signal change results are heavily dependent on gold nanostructure size and features. Sensing surfaces with larger nanoparticle diameters, which were prepared using electrodeposition at a constant potential, had a reduced aptamer packing density and exhibited diminished sensor performance. However, the equivalent packing density of polished electrodes did not yield the equivalent signal change. Other surfaces that were prepared using pulsed waveform electrodeposition achieved optimal signal change with a deposition time, tdep, of 120 s, and increased deposition time with enhanced electroactive surface area resulted in minimized signal changes and more rapid sensor degradation. By investigating sensing surfaces with varied morphologies, we have demonstrated that enhancing the electroactive surface does not always enhance the signal change of the sensor, and aptamer packing density alone does not dictate observed signal change trends. We anticipate that understanding how electrodeposition techniques enhance or diminish sensor performance will pave the way for further exploration of nanostructure-aptamer relationships, contributing to the future development of optimized, miniaturized electrochemical aptamer-based sensors for continuous, in vivo sensing.

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