Multigaps Embedded Nanoassemblies Enhance In Situ Raman Spectroscopy for Intracellular Telomerase Activity Sensing

The highly sensitive and quantitative biodetection of intracellular telomerase is challenging. A DNA‐driven nanoparticle self‐assembling pyramid encoding a Raman reporter (Cy5) is reported that detects telomerase in live cells. In the presence of the target, the telomerase primer is extended and the inner DNA chain is replaced, leading to the reduction in the surface‐enhanced Raman scattering (SERS) signal and the simultaneous recovery of the fluorescent signal. The SERS signal has a linear range for the detection of telomerase in situ of 1 × 10^–14 to 5 × 10^–11 IU, with a limit of detection of 6.2 × 10^–15 IU. The fluorescent signal is used to confirm the intracellular telomerase activity, demonstrating the efficacy of the designed pyramid probe. This biosensing strategy provides a reliable and ultrasensitive protocol for the quantification of biomarkers in living cells.     

A Universal,Label‐Free,and Sensitive Optical Enzyme‐Sensing System for Nuclease and Methyltransferase Activity Based on Light Scattering of Carbon Nanotubes

A label‐free, enzyme‐responsive nanosystem that uses a DNA/single‐walled carbon nanotube (SWNT) assembly as the substrate is demonstrated for the sensitive, universal detection of restriction and nonrestriction endonucleases as well as methyltransferases in a homogeneous solution on the basis of light scattering (LS) of carbon nanotubes. This protocol is based on the different binding affinities of SWNTs to single‐ and double‐stranded DNA. This difference can lead to different LS signals that can be used for the detection of nuclease cleavage activity. The assay only requires a label‐free oligonucleotide probe, significantly reducing the typical cost. The LS technique and the use of a nuclease‐specific oligonucleotide probe impart extraordinarily high sensitivity and selectivity. This light scattering assay is universal and label‐free with a detection limit of 5 × 10^?6 U μL^?1 for S1 nuclease, 1 × 10^?4 U μL^?1 for EcoRI endonuclease, and 1 × 10^?2 U μL^?1 for EcoRI methylase. In principle, this assay can be used to detect any kind of nuclease by simply changing the DNA sequences of the specific probe.     

Selective Determination of Dopamine on a Boron‐Doped Diamond Electrode Modified with Gold Nanoparticle/Polyelectrolyte‐coated Polystyrene Colloids

Negatively charged gold nanoparticles (AuNPs) and a polyelectrolyte (PE) have been assembled alternately on a polystyrene (PS) colloid by a layer‐by‐layer (LBL) self‐assembly technique to form three‐dimensional (Au/PAH)₄/(PSS/PAH)₄ multilayer‐coated PS spheres (Au/PE/PS multilayer spheres). The Au/PE/PS multilayer spheres have been used to modify a boron‐doped diamond (BDD) electrode. Cyclic voltammetry is utilized to investigate the properties of the modified electrode in a 1.0 M KCl solution that contains 5.0 × 10^?3 M K₃Fe(CN)₆, and the result shows a dramatically decreased redox activity compared with the bare BDD electrode. The electrochemical behaviors of dopamine (DA) and ascorbic acid (AA) on the bare and modified BDD electrode are studied. The cyclic voltammetric studies indicate that the negatively charged, three‐dimensional Au/PE/PS multilayer sphere‐modified electrodes show high electrocatalytic activity and promote the oxidation of DA, whereas they inhibit the electrochemical reaction of AA, and can effectively be used to determine DA in the presence of AA with good selectivity. The detection limit of DA is 0.8 × 10^?6 M in a linear range from 5 × 10^?6 to 100 × 10^?6 M in the presence of 1 × 10^?3 M AA.     

Detection of Glioma‐Derived Exosomes with the Biotinylated Antibody‐Functionalized Titanium Nitride Plasmonic Biosensor

Titanium nitride (TiN), as an excellent alternative plasmonic supporting material compared to gold and silver, exhibits tunable plasmonic properties in the visible and near‐infrared spectra. However, label‐free surface plasmon resonance biosensing with TiN is seldom reported due to lack of proper surface functionalization protocols. Herein, this study reports biotinylated antibody‐functionalized TiN (BAF‐TiN) for high‐performance label‐free biosensing applications. The BAF‐TiN biosensor can quantitatively detect exosomes of 30–200 nm extracellular vesicles, isolated from a human glioma cell line. The limit of detection for an exosomal membrane protein with the BAF‐TiN biosensor is found to be 4.29 × 10^?3µg mL^?1 for CD63, an exosome marker, and 2.75 × 10^?3µg mL^?1 for epidermal growth factor receptor variant‐III, a glioma specific mutant protein, respectively. In conclusion, combining the biocompatibility, high stability, and excellent label‐free sensing performance of TiN, the BAF‐TiN biosensor could have great potential for the detection of cancer biomarkers, including exosomal surface proteins.     

Ultrasensitive Detection of a Variety of Analytical Targets Based on a Functionalized Low‐Resistance AuNPs/β‐Ni(OH)2 Nanosheets/Ni Foam Sensing Platform

Simple, low‐cost and yet accurate, sensitive, and quantitative detection of a broad range of analytical targets by means of small footprint sensing devices has the potential to revolutionize medical diagnostics, food safety, and environmental monitoring. This work demonstrates a functional nucleic acids (FNAs) tethered AuNPs/β‐Ni(OH)₂ nanosheets (NS)/Ni foam nanocomposite as a miniaturized electrode. Through the rational design of a low‐barrier ohmic contact of AuNPs to β‐Ni(OH)₂ NS and a target mediated nanochannel electron transfer effect, a variety of analytical targets, ranging from a disease marker (thrombin, 16.3 × 10^?12 m detection limit) to an important biological cofactor (adenosine, 3.2 × 10^?12 m detection limit), and to a toxic metal ion (Hg²⁺, 3.1 × 10^?12 m detection limit), are detected with ultrasensitivity. The presence of target triggers the conformational change of FNAs, introducing strong steric hindrance and electrostatic repulsion to the diffusion of electron indicators toward the electrode surface, ultimately leading to the changes in impedance. A novel equivalent circuit considering the capacitive reactance is proposed to describe the 2D NS‐based impedance DNA bioelectrode. This sensing platform is easily applicable to the detection of many other targets in diverse sample matrices through the use of other suitable FNAs materials.     

Spectral efficiency improvement with SISO and SIMO in M‐QAM over millimeter‐wave links

This paper proposes a spectral efficiency improvement technique for millimeter wave (mmWave) links. The proposed technique provides an efficient utilization of the mmWave link capacity. This technique is applied in three cases the single‐input single‐output (SISO), single‐input multiple‐output (SIMO) with the maximal ratio combining and with the equal gain combining. The M‐ary quadrature amplitude modulation scheme is used in our work. The power series expansion is used for deriving closed‐form expressions for bit error rate (BER) performances in all studied cases. The BER closed‐form expressions are confirmed by the numerical solution of the integral equations. The simulation results show that a high spectral efficiency can be accomplished by the proposed technique. As well as the derived expressions closely match with the numerical solution of integration expressions at different values of modulations order the Rician factor. For instance, the spectral efficiency gain achievement is 8 at signal‐to‐noise ratio (SNR) equals 34 dB in the case of SISO system whereas in the case of SIMO system, the same gain is achieved at SNR equals 24 dB. As well as the BER performance is enhanced from 1.188 × 10^?4, 7.112 × 10^?4, 4.164 × 10^?3, and 3.286 × 10^?2 to 8.717 × 10^?16, 1.119 × 10^?12, 1.308 × 10^?9, and 4.905 × 10^?6 for M = 4, 16, 64, and 256, respectively, at SNR equals 30 dB.     

A Ratiometric Near‐Infrared Fluorescent Probe for Quantification and Evaluation of Selenocysteine‐Protective Effects in Acute Inflammation

Selenocysteine (Sec) is a primary kind of reactive selenium species in cells whose antioxidant roles in a series of liver diseases have been featured. However, it is difficult to determine Sec in living cells and in vivo due to its high reactivity and instability. This work reports a ratiometric near‐infrared fluorescent probe (Cy‐SS) for qualitative and quantitative determination of Sec in living cells and in vivo. The probe is composed of heptamethine cyanine fluorophore, the response unit bis(2‐hydroxyethyl) disulfide, and the liver‐targeting moiety d ‐galactose. Based on a detection mechanism of selenium–sulfur exchange reaction, the concentrations of Sec in HepG2, HL‐7702 cells, and primary mouse hepatocytes is determined as 3.08 ± 0.11 × 10^?6m , 4.03 ± 0.16 × 10^?6m and 4.34 ± 0.30 × 10^?6m , respectively. The probe can selectively accumulate in liver. The ratio fluorescence signal of the probe can be employed to quantitatively analyze the fluctuation of Sec concentrations in cells and mice models of acute hepatitis. The experimental results demonstrate that Sec plays important antioxidant and anti‐inflammatory roles during inflammatory process. And the levels of intracellular Sec have a close relationship with the degree of liver inflammation. The above imaging detections make this new probe a potential candidate for the accurate diagnosis of inflammation.     

Nanogap‐Rich Au Nanowire SERS Sensor for Ultrasensitive Telomerase Activity Detection: Application to Gastric and Breast Cancer Tissues Diagnosis

Telomerase has attracted much attention as a universal cancer biomarker because telomerase is overexpressed in more than 85% of human cancer cells while suppressed in normal somatic cells. Since a strong association exists between telomerase activity and human cancers, the development of effective telomerase activity assay is critically important. Here, a nanogap‐rich Au nanowire (NW) surface‐enhanced Raman scattering (SERS) sensor is reported for detection of telomerase activity in various cancer cells and tissues. The nanogap‐rich Au NWs are constructed by deposition of nanoparticles on single‐crystalline Au NWs and provided highly reproducible SERS spectra. The telomeric substrate (TS) primer‐attached nanogap‐rich Au NWs can detect telomerase activity through SERS measurement after the elongation of TS primers, folding into G‐quadruplex structures, and intercalation of methylene blue. This sensor enables us to detect telomerase activity from various cancer cell lines with a detection limit of 0.2 cancer cells mL^?1. Importantly, the nanogap‐rich Au NW sensor can diagnose gastric and breast cancer tissues accurately. The nanogap‐rich Au NW sensors show strong SERS signals only in the presence of tumor tissues excised from 16 tumor‐bearing mice, while negligible signals in the presence of heated tumor tissues or normal tissues. It is anticipated that nanogap‐rich Au NW SERS sensors can be used for a universal cancer diagnosis and further biomedical applications including a diverse biomarker sensing.     

Ultrasensitive Detection of Mitochondrial DNA Mutation by Graphene Oxide/DNA Hydrogel Electrode

Ultrasensitive detection of nucleic acid has attracted considerable attention recently in academic research and clinic diagnostics. Current approaches for DNA analysis involve complicated or expensive processes for labeling and often yield a high detection limit. In this study, a hydrogel electrode prepared from graphene oxide and fish sperm DNA is used for label?free mitochondrial DNA detection by impedimetric approach. The hydrogel has a bionic structure containing rich water and natural biomolecule fish sperm DNA that would benefit the adsorption and hybridization of DNA. Graphene oxide is a semiconductor and its conductivity can be improved by doping negatively charged DNA molecules. The result shows that the conductivity and impedance change of hydrogel electrode could be tuned by its length and component. The linear range for DNA detection by the optimized hydrogel is from 1.0 × 10^?9 to 1.0 × 10^?20 M with a detection limit of 1.0 × 10^?20 M. The result is ascribed to the bionic structure and tunable conductivity of hydrogel electrode. The hydrogel electrode has been used to detect the real DNA samples from patients of ovarian cancer with satisfactory results.     

Highly Reproducible Surface‐Enhanced Raman Scattering on a Capillarity‐Assisted Gold Nanoparticle Assembly

A facile method based on capillarity‐assisted assembly is used to fabricate high‐performance surface‐enhanced Raman scattering (SERS) substrates employing clean Au nanoparticles (NPs). This method is better than micro‐channel way because the former may supply large‐area uniform assembly and overcome the uneven radial distribution. Such densely‐arranged assembly of Au NPs exhibits high reproducibility and large Raman enhancement factors of 3 × 10¹⁰, arising from strong electromagnetic field coupling induced by adjacent Au NPs. The spot‐to‐spot SERS signals show that the relative standard deviation (RSD) in the intensity of the main Raman vibration modes (1310, 1361, 1509, 1650 cm^?1) of Rhodamine 6G at a concentration of 1 × 10^?10 M are consistently less than 20%, demonstrating good spatial uniformity and reproducibility. The SERS signals of sudan dye at a 1 × 10^?8 M concentration also shows high reproducibility with a low RSD of <20%. Further, the assembly substrate is stable, retaining excellent uniformity and sensitivity after storage for months. This assembly strategy integrating the advantages of low‐cost production, high sensitivity, and reproducibility would significantly facilitate practical SERS detection.     

An Alternative Copolymer of Carbazole and Thieno[3,4b]‐Pyrazine: Synthesis and Mercury Detection

A donor‐π‐acceptor (D‐π‐A) alternative copolymer of carbazole and thieno[3,4b]‐pyrazine [P(CZ‐TPZ)] is synthesized through a Wittig–Horner reaction. In dilute THF solution, the absorption spectrum of P(CZ‐TPZ) shows two absorption peaks at 306 and 452 nm, respectively, and the PL spectrum of the polymer solution displays a PL peak maximum at 543 nm. The polymer possesses relatively high sensitivity and selectivity for Hg²⁺ detection. Upon addition of Hg²⁺ into its THF solution (containing 0.3% CH₃CN), P(CZ‐TPZ) exhibits a new absorption peak at 560～600 nm and its emission was quenched dramatically. The Hg²⁺ detection shows high selectivity in comparison with the other cations of Na⁺, K⁺, Mg²⁺, Ba²⁺, Al³⁺, Cu²⁺, Cd²⁺, Pb²⁺, Ni²⁺, Mn²⁺, and Co²⁺. The Hg²⁺ detection limit of the polymer solution by emission quenching is found to be 1 × 10^?7 mol L^?1. P(CZ‐TPZ) also shows a selective chromogenic behavior toward Hg²⁺ with color change of the solution from yellow to blue dark which can be detected with the naked eye, the detection limit reaches 1 × 10^?6 mol L^?1 with a 1 × 10^?4 mol L^?1 polymer solution. The absorption and PL spectral change can be resumed after adding thiourea, therefore the sensing ability of the polymer is re‐usable with the treatment of thiourea. The results indicate that P(CZ‐TPZ) is a promising chemosensor for the Hg²⁺ detection.     

Gadolinium‐Doped Iron Oxide Nanoprobe as Multifunctional Bioimaging Agent and Drug Delivery System

In this study, a high‐performance T₁–T₂ dual‐model contrast agent by gadolinium‐doped iron oxide nanoparticle (GION) is developed. Following its development, the application of this agent in vivo by combining doxorubicin (DOX) and folic acid (FA) (FA–GION–DOX) for targeted drug delivery to monitor cancer treatment is explored. GION showed transverse and longitudinal relaxivities up to 182.7 × 10^?3 and 7.87 × 10^?3m ^?1 s^?1, respectively, upon Gd/Fe ratio in GION at 1/4. DOX released from FA–GION–DOX is pH dependent and only kills cancer cell after FA receptor‐mediated internalization into the acidic environment of endosomes and lysosomes. Systemic delivery of FA–GION–DOX significantly inhibits the growth of tumors and shows good magnetic resonance enhancement in a human cervical cancer xenograft model. Thus, FA–GION–DOX has a potential application for the targeted and magnetic resonance imaging guided therapy of cervical cancer.     

Desalination by Electrodialysis Using a Stack of Patterned Ion‐Selective Hydrogels on a Microfluidic Device

This study reports a novel approach for separation of charged species using anion‐exchange hydrogel (AEH) and cation‐exchange hydrogel (CEH) in a microfluidic device. The capillary line pinning technique, which is applied in this study, enables in situ fabrication of alternating AEH and CEH that are placed in confined compartments. Adjacent enriched and depleted streams are obtained in continuous flow when a potential difference is applied over the hydrogel stack. The desalination performance of the microchip is demonstrated at different salt concentrations (0.01 × 10^?3–1× 10^?3m sodium chloride), potentials (10–100 V), current densities (12–28 A m^?2), and liquid flow rates (0–5 µL min^?1). It is shown that the microchip is able to remove ≈75% of the salt initially present in the depleted outlet streams at inlet stream concentrations of 1 × 10^?3m sodium chloride. Besides desalination, the microchip allows study of ion transport in the ion‐selective hydrogels to elucidate the interplay of transport phenomena at the electrolyte–hydrogel interface during the desalination process.     

Control of Crystal Growth toward Scalable Fabrication of Perovskite Solar Cells

With the impressive record power conversion efficiency (PCE) of perovskite solar cells exceeding 23%, research focus now shifts onto issues closely related to commercialization. One of the critical hurdles is to minimize the cell‐to‐module PCE loss while the device is being developed on a large scale. Since a solution‐based spin‐coating process is limited to scalability, establishment of a scalable deposition process of perovskite layers is a prerequisite for large‐area perovskite solar modules. Herein, this paper reports on the recent progress of large‐area perovskite solar cells. A deeper understanding of the crystallization of perovskite films is indeed essential for large‐area perovskite film formation. Various large‐area coating methods are proposed including blade, slot‐die, evaporation, and post‐treatment, where blade‐coating and gas post‐treatment have so far demonstrated better PCEs for an area larger than 10 cm². However, PCE loss rate is estimated to be 1.4 × 10^?2% cm^?2, which is 82 and 3.5 times higher than crystalline Si (1.7 × 10^?4% cm^?2) and thin film technologies (≈4 × 10^?3% cm^?2) respectively. Therefore, minimizing PCE loss upon scaling‐up is expected to lead to PCE over 20% in case of cell efficiency of >23%.     

Heat Dissipation of Transparent Graphene Defoggers

In spite of recent successful demonstrations of flexible and transparent graphene heaters, the underlying heat‐transfer mechanism is not understood due to the complexity of the heating system. Here, graphene/glass defoggers are fabricated and the dynamic response of the temperature as a function of input electrical power is measured. The graphene/glass defoggers reveal shorter response times than Cr/glass defoggers. Furthermore, the saturated temperature of the graphene/glass defoggers is higher than for Cr/glass defoggers at a given input electrical power. The observed dynamic response to temperature is well‐fitted to the power‐balance model. The response time of graphene/glass defogger is shorter by 44% than that of the Cr/glass defogger. The convective heat‐transfer coefficient of graphene is 12.4 × 10^?4 W cm^?2 °C^?1, similar to that of glass (11.1 × 10^?4 W cm^?2 °C^?1) but smaller than that of chromium (17.1 × 10^?4 W cm^?2 °C^?1). The graphene‐based system reveals the lowest convective heat‐transfer coefficient due to its ideal flat surface compared to its counterparts of carbon nanotubes (CNTs) and reduced graphene oxide (RGO)‐based systems.     

Ultrasensitive Room‐Temperature Terahertz Direct Detection Based on a Bismuth Selenide Topological Insulator

Despite their huge application capabilities, millimeter‐ and terahertz‐wave photodetectors still face challenges in the detection scheme. Topological insulators (TIs) are predicted to be promising candidates for long‐wavelength photodetection, due to the presence of Dirac fermions in their topologically protected surface states. However, photodetection based on TIs is usually hindered by the large dark current, originating from the mixing of bulk states with topological surface states (TSSs) in most realistic samples of TIs. Here millimeter and terahertz detectors based on a subwavelength metal–TI–metal (MTM) heterostructure are demonstrated. The achieved photoresponse stems from the asymmetric scattering of TSS, driven by the localized surface plasmon‐induced terahertz field, which ultimately produces direct photocarriers beyond the interband limit. The device enables high responsivity in both the self‐powered and bias modes even at room temperature. The achieved responsivity is over 75 A/W, with response time shorter than 60 ms in the self‐powered mode. Remarkably, the responsivity increases by several orders of magnitude in the biased configuration, with the noise‐equivalent power (NEP) of 3.6 × 10^?13 W Hz^?1/2 and a detectivity of 2.17 × 10¹¹ cm Hz^?1/2 W^?1 at room temperature. The detection performances open a way toward realistic exploitation of TIs for large‐area, real‐time imaging within long‐wavelength optoelectronics.     

Lithium Titanate Tailored by Cathodically Induced Graphene for an Ultrafast Lithium Ion Battery

Nonoxidative cathodically induced graphene (CIG) here incorporates conductive agents for Li₄Ti₅O₁₂ (LTO) anode materials. The tailored LTO/CIG composite is fabricated by controlled hydrolysis of tetrabutyl titanate in the presence of nonoxidative defect‐free cathodically induced graphene (CIG) and oxalic acid in a mixed solvent of ethanol and water, followed by hydrothermal reaction and a calcination treatment. Due to the introduction of defect‐free graphene, the resulting LTO/CIG composite shows an excellent electrical conductivity (1.2 × 10^?4 S cm^?1) and Li⁺ diffusion coefficient (1.61 × 10^?12 cm² s^?1). As a result, the tuned LTO/CIG composite exhibits outstanding electrochemical performance, including excellent cycling stability (the capacity retention ratios after 500 cycles at 0.5 C is 96.2%) and a remarkable rate capability (162 mAh g^?1 at 10C, 126 mAh g^?1 at 100 C). A specific energy of 272 Wh kg^?1 at power of 136 W kg^?1 is observed when cycling against Li‐foil. Even during 36 s of charge/discharge, the specific energy of LTO/CIG composite remains at 166 Wh kg^?1.     

Improved Interface and Electrical Properties by Inserting an Ultrathin SiO2 Buffer Layer in the Al2O3/Si Heterojunction

An ultrathin SiO₂ interfacial buffer layer is formed using the nitric acid oxidation of Si (NAOS) method to improve the interface and electrical properties of Al₂O₃/Si, and its effect on the leakage current and interfacial states is analyzed. The leakage current density of the Al₂O₃/Si sample (8.1 × 10^?9 A cm^?2) due to the formation of low‐density SiO_x layer during the atomic layer deposition (ALD) process, decreases by approximately two orders of magnitude when SiO₂ buffer layer is inserted using the NAOS method (1.1 × 10^?11 A cm^?2), and further decreases after post‐metallization annealing (PMA) (1.4 × 10^?12 A cm^?2). Based on these results, the influence of interfacial defect states is analyzed. The equilibrium density of defect sites (N_d) and fixed charge density (N_f) are both reduced after NAOS and then further decreased by PMA treatment. The interface state density (D_it) at 0.11 eV decreases about one order of magnitude from 2.5 × 10¹² to 7.3 × 10¹¹ atoms eV^?1 cm^?2 after NAOS, and to 3.0 × 10¹⁰ atoms eV^?1 cm^?2 after PMA. Consequently, it is demonstrated that the high defect density of the Al₂O₃/Si interface is drastically reduced by fabricating ultrathin high density SiO₂ buffer layer, and the insulating properties are improved.     

A Protein‐Nanocellulose Paper for Sensing Copper Ions at the Nano‐ to Micromolar Level

Tracing heavy metals is a crucial issue in both environmental and medical samples. In this work, a sensing biomolecule, the cyanobacterial C‐phycocyanin (CPC), is integrated into a nanocellulose matrix, and with this, a biosensor for copper ions is developed. The assembly of CPC‐functionalized nanocellulose into a red‐fluorescent, copper‐sensitive hybrid film “CySense”, enhances protein stability and facilitates the reuse and the regeneration of the sensor for several cycles over 7 days. CySense is suitable for the analysis of complex medical samples such as human serum filtrate. The reported biosensor reliably detects copper ion contents with a lower detection limit of 200 × 10^?9m and an IC50 of 4.9 × 10^?6m as changes in fluorescence emission intensity that can be measured with a fluorimeter or a microarray laser scanner.     

Vectorially Imprinted Hybrid Nanofilm for Acetylcholinesterase Recognition

Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) is accomplished by a hybrid nanofilm composed of a propidium‐terminated self‐assembled monolayer (Prop‐SAM) which binds AChE via its peripheral anionic site (PAS) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate‐modified derivative of 3,4‐propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop‐SAM nanofilm covered electrode is detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine is dependent on the AChE concentration from ≈0.04 × 10^?6 to 0.4 × 10^?6m . An imprinting factor of 9.9 is obtained for the hybrid MIP, which is among the best values reported for protein imprinting. The dissociation constant characterizing the strength of the MIP‐AChE binding is 4.2 × 10^?7m indicating the dominant role of the PAS‐Prop‐SAM interaction, while the benefit of the MIP nanofilm covering the Prop‐SAM layer is the effective suppression of the cross‐reactivity toward competing proteins as compared with the Prop‐SAM. The threefold selectivity gain provided by i) the “shape‐specific” MIP filter, ii) the propidium‐SAM, iii) signal generation only by the AChE bound to the nanofilm shows promise for assessing AChE activity levels in cerebrospinal fluid.