Microfluidic paper-based chemiluminescence sensing platform based on functionalized CaCO3 for time-resolved multiplex detection of avian influenza virus biomarkers

Multiplex detection can enhance diagnostic precision and improve diagnostic efficiency, providing important assistance for epidemiological investigation and epidemic prevention. There is a great need for multi-detection sensing platforms to accurately diagnose diseases. Herein, we reported a μPAD-based chemiluminescence (CL) assay for ultrasensitive multiplex detection of AIV biomarkers, based on three DNAzyme/Lum/PEI/CaCO3. Three time-resolved CL signals were sequentially generated with detection limits of 0.32, 0.34, and 0.29 pM for H1N1, H7N9, and H5N1, respectively, and with excellent selectivity against interfering DNA. The recovery test in human serum displayed satisfactory analysis capabilities for complex biological samples. The μPAD-based CL assay achieved multiplex detection within 70 s, with a high time resolution of 20 s. The proposed strategy has the advantages of low cost, high sensitivity, good selectivity, and wide time resolution, the μPAD-based CL assay has shown great potential in the early and accurate diagnosis of diseases.

G-quadruplex-hemin DNAzyme functionalized nanopipettes: Fabrication and sensing application

Solid-nanopores/nanopipettes have the exquisite ability to reveal the changes in molecular volume due to the advantages of adjustable size, good rigidity and low noise. Herein, a new platform for sensing application was established based on G-quadruplex-hemin DNAzyme (GQH) functionalized gold-coated nanopipettes. In this method, GQH was immobilized on gold-coated nanopipette, which could be used as a catalyst for the reaction of H₂O₂ with 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) to promote the conversion of ABTS to ABTS⁺ ions inside gold-coated nanopipette, and the change of transmembrane ion current could be monitored in real time. At the optimal conditions, there was a correlation between the ion current and the concentration of H₂O₂ in a certain range, which could be used for the hydrogen peroxide sensing. The GQH immobilized nanopipette provides a useful platform to investigate enzymatic catalysis in confined environment, which can be used in electrocatalysis, sensing and fundamental electrochemistry.

Single-Molecule Investigation of the Protein-Aptamer Interactions and Sensing Application Inside the Single Glass Nanopore

Solid-state nanopores offer a nanoconfined space for a single-molecule sensing strategy. Evaluating the behavior of proteins and protein-related interactions at the single-molecule level is becoming more and more important for a better understanding of biological processes and diseases. In this work, the aptamer-functionalized nanopore was prepared as the sensing platform for kinetic analysis of the carcinoembryonic antigen (CEA) with its aptamers, which is an important cancer biomarker. CEA molecules were captured by the aptamers immobilized on the inner surface of the nanopore, and there was a complicated interaction between the CEA molecules and the aptamer, which is the process of association and dissociation. This could be used to measure the dynamics of aptamer-protein interactions without labeling. The kinetic analysis could be evaluated at the single-molecule level to interpret the dissociation constants of the binding and dissociation processes. Results showed that the translocation of CEA molecules in a functionalized nanopore had a deep blockades degree and long duration compared with nanopore modified with bare gold, which could be used for CEA sensing. This protein and protein-related interaction we designed provides new insights for evaluating the binding affinity, which will be beneficial for protein sensing and immunoassays.

Electrokinetic behavior of conical nanopores functionalized with two polyelectrolyte layers: effect of pH gradient

The behavior of ionic current rectification of a conical nanopore functionalized with two polyelectrolyte (PE) layers via layer-by-layer deposition subject to an extra applied pH gradient is investigated theoretically. The applied pH, the electric potential, the half-cone angle of the conical nanopore, and the fixed charge densities of the PE layers are examined in detail for their influence on the ionic current rectification (ICR) behavior of the nanopore. We found that this behavior depends highly on the direction of the pH gradient, which arises because the associated electroosmotic flow plays a significant role. The mechanisms of ionic transport in the present pH asymmetric system are discussed. The results gathered reveal that the ICR behavior of a nanopore can be tuned effectively by applying an extra pH gradient. We also examine the case where two PE layers are uniformly merged into one layer. In this case, both the fixed charge density and the concentration profile are quite different from those when two PE layers are present.

Mechanisms of Enzymatic Transduction in Nanochannel Biosensors

The immobilization of enzymes in solid-state nanochannels is a new avenue for the design of biosensors with outstanding selectivity and sensitivity. This work reports the first theoretical model of an enzymatic nanochannel biosensor. The model is applied to the system previously experimentally studied by Lin, et al. (Anal. Chem. 2014, 86, 10546): a hourglass nanochannel modified by glucose oxidase for the detection of glucose. Our predictions are in good agreement with experimental observations as a function of the applied potential, pH and glucose concentration. The sensing mechanism results from the combination of three processes: i) the establishment of a steady-state proton concentration gradient due to a reaction-diffusion mechanism, ii) the effect of that gradient on the charge of the adsorbed enzymes and native surface groups, and iii) the effect of the resulting surface charge on the ionic current. Strategies to improve the sensor performance based on this mechanism are identified and discussed.

Solid-state and polymer nanopores for protein sensing: A review

In two decades, the solid state and polymer nanopores became attractive method for the protein sensing with high specificity and sensitivity. They also allow the characterization of conformational changes, unfolding, assembly and aggregation as well the following of enzymatic reaction. This review aims to provide an overview of the protein sensing regarding the technique of detection: the resistive pulse and ionic diodes. For each strategy, we report the most significant achievement regarding the detection of peptides and protein as well as the conformational change, protein-protein assembly and aggregation process. We discuss the limitations and the recent strategies to improve the nanopore resolution and accuracy. A focus is done about concomitant problematic such as protein adsorption and nanopore lifetime.

Regional and functional division of functional elements of solid-state nanochannels for enhanced sensitivity and specificity of biosensing in complex matrices

Solid-state nanochannels (SSNs) provide a promising approach for biosensing due to the confinement of molecules inside, their great mechanical strength and diversified surface chemical properties; however, until now, their sensitivity and specificity have not satisfied the practical requirements of sensing applications, especially in complex matrices, i.e., media of diverse constitutions. Here, we report a protocol to achieve explicit regional and functional division of functional elements at the outer surface (FE_OS) and inner wall (FE_IW) of SSNs, which offers a nanochannel-based sensing platform with enhanced specificity and sensitivity. The protocol starts with the fabrication and characterization of the distribution of FE_OS and FE_IW. Then, the evaluation of the contributions of FE_OS and FE_IW to ionic gating is described; the FE_IW mainly regulate ionic gating, and the FE_OS can produce a synergistic effect. Finally, hydrophobic or highly charged FE_OS are applied to ward off interference molecules, non-target molecules that may affect the ionic signal of nanochannels, which decreases false signals and helps to achieve the highly specific ionic output in complex matrices. Compared with other methods currently available, this method will contribute to the fundamental understanding of substance transport in SSNs and provide high specificity and sensitivity in SSN-based analyses. The procedure takes 3-6 d to complete.

Nanobubble-controlled nanofluidic transport

Nanofluidic platforms offering tunable material transport are applicable in biosensing, chemical detection, and filtration. Prior studies have achieved selective and controllable ion transport through electrical, optical, or chemical gating of complex nanostructures. Here, we mechanically control nanofluidic transport using nanobubbles. When plugging nanochannels, nanobubbles rectify and occasionally enhance ionic currents in a geometry-dependent manner. These conductance effects arise from nanobubbles inducing surface-governed ion transport through interfacial electrolyte films residing between nanobubble surfaces and nanopipette walls. The nanobubbles investigated here are mechanically generated, made metastable by surface pinning, and verified with cryogenic transmission electron microscopy. Our findings are relevant to nanofluidic device engineering, three-phase interface properties, and nanopipette-based applications.

Tunable Current Rectification and Selectivity Demonstrated in Nanofluidic Diodes through Kinetic Functionalization

The possibility of tuning the current rectification and selectivity in nanofluidic diodes is demonstrated both experimentally and theoretically through dynamically functionalizing a conical nanopore with poly-l-lysine. We identified an optimum functionalization time equivalent to optimum modification depth that assures the highest rectification degrees. Results showed that the functionalization time-dependent rectification behavior of nanofluidic diodes is dominated by the properties of current at positive voltages that in our electrode configuration indicate the "on" state of the diode and accumulation of ions in the nanopore. The functionalization time also tunes the ion selectivity of the diode. If the functionalization time is sufficiently short, an unusual depletion of counterions near the bipolar interface results in a cation-selective nanopore. However, a further increase in the duration of functionalization renders a nanopore that is an anion-selective nanopore. The dynamic functionalization presented in this Letter enables tuning ion selectivity of nanopores.

Surface coatings for solid-state nanopores

Since their introduction in 2001, solid-state nanopores have been increasingly exploited for the detection and characterization of biomolecules ranging from single DNA strands to protein complexes. A major factor that enables the application of nanopores to the analysis and characterization of a broad range of macromolecules is the preparation of coatings on the pore wall to either prevent non-specific adhesion of molecules or to facilitate specific interactions of molecules of interest within the pore. Surface coatings can therefore be useful to minimize clogging of nanopores or to increase the residence time of target analytes in the pore. This review article describes various coatings and their utility for changing pore diameters, increasing the stability of nanopores, reducing non-specific interactions, manipulating surface charges, enabling interactions with specific target molecules, and reducing the noise of current recordings through nanopores. We compare the coating methods with respect to the ease of preparing the coating, the stability of the coating and the requirement for specialized equipment to prepare the coating.

Electrical Field Regulation of Ion Transport in Polyethylene Terephthalate Nanochannels

Rectified ion transport in nanochannels is the basis of ion channels in biological cells and has inspired emerging nanochannel applications in ion separation, Coulter counters, and biomolecule detection and nanochannel energy harvesters. In this work we fabricated a polyethylene terephthalate (PET) conical nanochannel using latent ion track etching technique and then systematically studied the ion transport and influence of cation species on the nanochannel surface with cyclic I-V measurement. We discovered the electrical regulation of the reversible and irreversible modification of the nanochannel transportation by bivalent and trivalent cations, revealing the existence of the switching threshold voltage which can control the current rectification in bivalent solution. The proposed mechanism of the transport state transition in the PET nanochannel mimics behaviors of voltage-gated biological ion channels. These findings provide new insight into the understanding of the ion channel signaling and translocation control of charged particles in nanochannel applications.

One-step sensitive thrombin detection based on a nanofibrous sensing platform

Convenient and time-saving one-step strategies for detecting ultralow concentrations of protein biomarkers play key roles in rapid disease diagnosis. In this study, we report a one-step detection method based on a nanofibrous sensing platform via the combination of proximity-induced DNA strand displacement (PiDSD), catalytic hairpin assembly (CHA) amplification and thioflavin T (ThT) binding. The interface behaviors on the nanofibrous membrane were studied to promote interface reaction kinetics and thermodynamics. Thrombin was used as a model biomarker, and the nanofibrous sensing platform achieved a limit of detection as low as 1.0 pM, a wide linear range of 50 pM to 5 nM, excellent specificity and good long-term stability. Compared with previous one-step thrombin detection methods, our one-step detection method is label-free, convenient and much more sensitive; it has potential applications for protein detection in point-to-care testing (POCT) and early diagnosis.

Plasmonic nanoplatform for point-of-care testing trace HCV core protein

Early diagnosis of hepatitis C virus (HCV) infection is still urgently desired as there is a global healthy burden and no vaccine available. In this work, a plasmonic nanoplatform was engineered with catalytic hairpin assembly (CHA) amplification reaction specifically of HCV core protein (HCVcp), G-quadruplex/hemin DNAzyme and nanofibrous membrane together. HCVcp was detected in whole serum at the ultralow concentration of 1.0 × 10^-4 pg/mL with naked eye. By testing serum samples from 30 donors with different viral loads, detection sensitivity of the plasmonic nanoplatform turned out to be much better than that of the commercial ELISA kit. In addition, the plasmonic nanoplatform exhibited high specificity, excellent reusability and long-term stability. Naked-eye detection based on the plasmonic nanoplatform is expected to have potential applications in point-of-care testing (POCT) and early diagnosis of hepatitis C and other infectious diseases.

Selective Single Molecule Nanopore Sensing of microRNA Using PNA Functionalized Magnetic Core-Shell Fe3O4-Au Nanoparticles

Solid-state nanopores have been employed as useful tools for single molecule analysis due to their advantages of easy fabrication and controllable diameter, but selectivity is always a big concern for complicated samples. In this work, functionalized magnetic core-shell Fe₃O₄-Au nanoparticles, which acted as a molecular carrier, were introduced into nanopore electrochemical system for microRNA sensing in complicated samples with high sensitivity, selectivity and signal-to-noise ratio (SNR). This strategy is based on the specific affinity between neutral peptide nucleic acids (PNA)-modified Fe₃O₄-Au nanoparticles and negative miRNA, and the formation of negative Fe₃O₄-Au-PNA-miRNA complex, which can pass through the nanopore by application of a positive potential and eliminate neutral Fe₃O₄-Au-PNA complex. To detect miRNA in complicated samples, a magnet has been used to separate Fe₃O₄-Au-PNA-miRNA complex with good selectivity. We think this is a facile and effective method for the detection of different targets at single molecular level, including nucleic acids, proteins, and other small molecules, which will open up a new approach in the nanopore sensing field.

Single conical track-etched nanopore for a free-label detection of OSCS contaminants in heparin

The heparin contamination by oversulfated chondroitin (OSCS) was at the origin of one major sanitary problem of last decade. Here we propose a novel strategy to detect OSCS from heparin solution based on conical nanopore functionalized with poly-L-lysine deposition to ensure its re-usability. This sensor is an excellent to detect low heparin concentration (from 25 ng/ml to 3 μg/ml) using the modification of ionic current rectification. It also allows following the kinetic of heparin degradation by heparinase with a good correlation with results obtained by classical methods. The sensor is sensitive to the inhibition of heparinase by OSCS until a concentration of 200 pg/ml representing 0.01% in weight in a heparin. This resolution is one order of magnitude lower than the one obtained by chromatography. For the first time, it was reached without fluorescence labeling.

Nanopore Functionalized by Highly Charged Hydrogels for Osmotic Energy Harvesting

The salinity gradient between brine and fresh water is an abundant source of power which can be harvested by two major membrane methods: pressure-retarded osmosis and reversed electrodialysis. Nowadays, the latter technology is close to real application, but it still suffers from low power yield. Low membrane selectivity and complex membrane fabrication are the main limiting factors. To improve that, we design a couple of ion-selective membranes based on the track-etched polymer nanopore functionalized by highly charged hydrogels. Two nanopore geometries are compared (cylindrical and conical shape) to generate osmotic energy with gel functions and more importantly can be scaled up. Experiments from the single nanopore and multipore membrane to stacked membranes show complete characterization from ionic transportation to energy generation and a clear relationship from the single pore to stacked membranes. In the actual experiment conditions, a power density of 0.37 W m^-2 at pH 7 was achieved. By improving ionic tracks and reducing intermembrane distances, it can be a good candidate for industrial applications.

Metal alloy solid-state nanopores for single nanoparticle detection

Solid-state nanopore technology for nanoparticle sensing is considered for the development of analytical tools to characterise their size, shape or zeta potential. In this field, it is crucial to understand how the nanopore inner surface influences the dynamic of nanoparticle translocation. Here, three single nanopores directly drilled in metal alloys (titanium nitride, titanium-tantalum and tantalum) are considered. The translocation of polystyrene nanoparticles coated with ssDNA is investigated by the resistive pulse method at different concentrations and voltages. The results show that the nanoparticle energy barrier for entrance into the pore decreases for nanopores that exhibits a higher surface energy and hydrophilicity, while the dwell time is found to depend on the nanopore surface state. Overall, this study demonstrates that the control of nanopore surface state must be taken into account for the resistive pulse experiments for nanoparticle detection.

Impact of Polyelectrolyte Multilayers on the Ionic Current Rectification of Conical Nanopores

Single conical nanopores were functionalised layer by layer with weak polyelectrolytes. We studied their influence on the ionic diode properties We have considered different couples of polyelectrolytes: poly-l-lysine/poly(acrylic acid) and poly(ethyleneimine)/poly(acrylic acid) as well as the influence of cross-linking. The results show that the nanopores decorated with poly(ethyleneimine)/poly(acrylic acid) exhibit an interesting behavior. Indeed, at pH 3, the nanopore is open only at the low salt concentration, while at pH 7, it is already open. The nanopores functionalized with poly-l-lysine/poly(acrylic acid) do not show an inversion of ionic transport properties with the pH as expected. After cross-linked to prevent large conformational changes, the ionic diode properties are dependent on the pH.

Unexpected ionic transport behavior in hydrophobic and uncharged conical nanopores

We investigated ionic transport behavior in the case of uncharged conical nanopores. We observed unexpected ionic transport behaviour, which is attributed to a predominant effect of slippage due to water organization at the solid/liquid interface.

Mussel-inspired fabrication of porous anodic alumina nanochannels and a graphene oxide interfacial ionic rectification device

A mussel-inspired new interfacial ionic rectification device is fabricated using porous anodic alumina nanochannels and graphene oxide via dopamine polymerization.

Functionalization of single solid state nanopores to mimic biological ion channels: A review

In nature, ion channels are highly selective pores and act as gate to ensure selective ion transport, allowing ions to cross the membrane. By mimicking them, single solid state nanopore devices emerge as a new, powerful class of molecule sensors that allow for the label-free detection of biomolecules (DNA, RNA, and proteins), non-biological polymers, as well as small molecules. In this review, we exhaustively describe the fabrication and functionalization techniques to design highly robust and selective solid state nanopores. First we outline the different materials and methods to design nanopores, we explain the ionic conduction in nanopores, and finally we summarize some techniques to modify and functionalize the surface in order to obtain biomimetic nanopores, responding to different external stimuli.

Bioinspired Energy Conversion in Nanofluidics: A Paradigm of Material Evolution

Well-developed structure-function relationships in living systems have become inspirations for the design and application of innovative materials. Building artificial nanofluidic systems for energy conversion undergoes three essential steps of structural and functional development with the uptake of separate biological inspirations. This research field started from the mimicking of the bioelectric function of electric eels, wherein a transmembrane ion concentration gradient is converted into ultrastrong electrical impulses via membrane-protein-regulated ion transport. On a small scale, solid-state nanopores are transformed from cylindrical to cone-shaped to acquire asymmetric ion-transport properties; they also further gain versatile responsiveness via chemical modification. These features mimic the rectifying and gating functions of the biological ion channels. Toward large-scale integration and real-world applications, the structure of the nanofluidic system evolves from a one-dimensional straight-channel to a two-dimensional layered membrane, inspired by the layered microstructure of nacre. The research progress, current challenges, and future perspectives of this growing field are highlighted and discussed from the viewpoint of material evolution.

Cesium-Induced Ionic Conduction through a Single Nanofluidic Pore Modified with Calixcrown Moieties

We demonstrate experimentally and theoretically a nanofluidic device for the selective recognition of the cesium ion by exploiting host-guest interactions inside confined geometry. For this purpose, a host molecule, i.e., the amine-terminated p-tert-butylcalix[4]arene-crown (t-BuC[4]C-NH₂), is successfully synthesized and functionalized on the surface of a single conical nanopore fabricated in a poly(ethylene terephthalate) (PET) membrane through carbodiimide coupling chemistry. On exposure to the cesium cation, the t-BuC[4]C-Cs⁺ complex is formed through host-guest interaction, leading to the generation of positive fixed charges on the pore surface. The asymmetrical distribution of these groups along the conical nanopore leads to the electrical rectification observed in the current-voltage (I-V) curve. On the contrary, other alkali cations are not able to induce any significant change in the rectification characteristics of the nanopore. The success of the chemical modification is monitored from the changes in the electrical readout of the nanopore. Theoretical results based on the Nernst-Planck and Poisson equations further demonstrate the validity of the experimental approach to the cesium-induced ionic conduction of the nanopore.

Mimicking pH-Gated Ionic Channels by Polyelectrolyte Complex Confinement Inside a Single Nanopore

Biological channels have served as inspiration to design stimuli-response artificial nanopores. Here we propose an original approach to design a pH-gate nanopore based on polyethylenimine and chondroitin-4-sulfate (ChS) layer-by-layer self-assembly. This approach is interesting because it is rapid and permits monitoring in real time of functionalization. The study of ionic transport through these single nanopores reveals a selectivity on anions and pH-gate properties at low salt concentration. It is open at pH below 4 or 5 depending on salt concentration. These properties are explained by the modification of both charge and conformation of ChS as well as swelling of the polyelectrolyte complex.

Biomimetic solution against dewetting in a highly hydrophobic nanopore

A water molecule is the foundation of life and is the primary compound in every living system. While many of its properties are understood in a bulk solvent, its behavior in a small hydrophobic nanopore still raises fundamental questions. For instance, a wetting/dewetting transition in a hydrophobic solid-state or a polymer nanopore occurs stochastically and can only be prevented by external physical stimuli. Controlling these transitions would be a primary requirement to improve many applications. Some biological channels, such as gramicidin A (gA) proteins, show a high rate of water and ion diffusion in their central subnanochannel while their external surface is highly hydrophobic. The diameter of this channel is significantly smaller than the inner size of the lowest artificial nanopore in which water drying occurs (i.e. 1.4 nm). In this paper, we propose an innovative idea to generate nanopore wetting as a result of which the application of an external field is no longer required. In a nanopore, the drying or wetting of the inner walls occurs randomly (in experiments and in simulations). However, we have shown how the confinement of gA, in a dried hydrophobic nanopore, rapidly generates a stable wetting of the latter. We believe that this simple idea, based on biomimetism, could represent a real breakthrough that could help to improve and develop new nanoscale applications.

Sensitive Zn(2+) sensor based on biofunctionalized nanopores via combination of DNAzyme and DNA supersandwich structures

The sensitivity of detection based on biofunctionalized nanopores is limited since the target-to-signal ratio is 1 : 1. Isothermal amplification is a promising amplification strategy at constant temperature due to its easy operation, quick results, PCR-like sensitivity, low cost and energy efficiency. In the present work, the isothermally amplified detection of Zn(2+) is achieved by using a DNA supersandwich structure and Zn(2+)-requiring DNAzymes. The DNA supersandwich structures, due to the multiple amplification of nucleic acids, heavily plug the nanopore. Simultaneously, the DNA supersandwich structures bond with the sessile probe (SP) of the substrate in the nanopore which partially hybridizes with DNAzymes. In the presence of Zn(2+), the Zn(2+)-requiring DNAzyme cleaves the SP into two fragments, while the DNA supersandwich structures are peeled off and the ionic pathway is unimpeded. A steep drop and a sequential complete recovery of the current occur in the I-V plot when the DNA supersandwich structures are decorated and peeled off. In the present system, the reliable detection limit of Zn(2+) is as low as 1 nM. Discrimination between different types of ions (Cu(2+), Hg(2+), Pb(2+)) is achieved.

Fast and reversible functionalization of a single nanopore based on layer-by-layer polyelectrolyte self-assembly for tuning current rectification and designing sensors

We report a reversible functionalization of conical nanopores based on layer-by-layer self-assembly of poly-l-lysine and poly(styrene sulfonate).

Biotinylated Cyclophane: Synthesis, Cyclophane-Avidin Conjugates, and Their Enhanced Guest-Binding Affinity

Cationic and anionic cyclophanes bearing a biotin moiety were synthesized as a water-soluble host (1a and 1b, respectively). Both hosts 1a and 1b were found to strongly bind avidin with binding constants of 1.3 × 10(8) M(-1), as confirmed by surface plasmon resonance measurements. The present conjugate of 1a with avidin (1a-avidin) showed an enhanced guest binding affinity toward fluorescence guests such as TNS and 2,6-ANS. The K values of 1a-avidin conjugate with TNS and 2,6-ANS were ~19-fold larger than those of monocyclic cyclophane 1a with the identical guests. Favorable hydrophobic and electrostatic interactions between 1a-avidin and TNS were suggested by computer-aided molecular modeling calculations. Moreover, addition of excess biotin to the complexes of 1a-avidin with the guests resulted in dissociation of 1a-avidin to avidin and 1a having less guest-binding affinity. Conversely, such enhancements in the guest-binding affinity were not obviously observed for the conjugate of anionic 1b with avidin (1b-avidin) due to electrostatic repulsion between anionic 1b and anionic guests.

Atomic layer deposition of biobased nanostructured interfaces for energy, environmental and health applications

The most fundamental phenomena in the immobilising of biomolecules on the nanostructured materials for energy, environmental and health applications are the control of interfaces between the nanostructures/nanopores and the immobilized biomaterials. Thus, the throughput of all those biobased nanostructured materials and devices can be improved or controlled by the enhanced geometric area of the nanostructured interfaces if an efficient immobilization of the biomolecules is warranted. In this respect, an accurate control of the geometry (size, porosity, etc.) and interfaces is primordial to finding the delicate balance between large/control interface areas and good immobilization conditions. Here, we will show how the atomic layer deposition (ALD) can be used as a tool for the creation of controlled nanostructured interfaces in which the geometry can be tuned accurately and the dependence of the physical-chemical properties on the geometric parameters can be studied systematically in order to immobilize biomolecules. We will show mainly examples of how these methods can be used to create single nanopores for mass spectroscopy and DNA sequencing, and membrane for gas separation and water treatment in which the performance varies with the nanostructure morphologies/interfaces and the immobilization conditions.