Nanosensor Design Packages: A Smart and Compact Development for Metal Ions Sensing Responses

With recent advances in mesostructured materials and nanotechnologies, new methods are emerging to design optical sensors and biosensors, and to develop highly sensitive solid sensors. Here, highly sensitive, low cost, simple nanosensor designs for naked‐eye detection of toxic metal ions are successfully developed by the immobilization of commercially available α,β,γ,δ‐tetrakis(1‐methylpyridinium‐4‐yl)porphine p‐toluenesulfonate (TMPyP) and diphenylcarbazide (DPC), and chemically synthesized 4‐n‐dodecyl‐6‐(2‐thiazolylazo) resorcinol (DTAR) and 4‐n‐dodecyl‐6‐(2‐pyridylazo) phenol (DPAP) chromophore molecules into spherical nanosized cavities and surfaces. A rational strategy was crucial to develop optical nanosensors that can be used to control accurate recognition and signaling abilities of analyte species for ion‐sensing purposes. This is the first reported evidence of the significant key factors of the development of receptors as ‘indicator dyes' and surface‐confinement materials as ‘carriers' to broadening the applicability of optical chemical sensors for selective discrimination of trace levels of toxic analytes. In all the nanosensor design techniques presented here, a dense pattern of immobilized hydrophobic ‘neutral' and hydrophilic ‘charged' chromophores with intrinsic mobility, as a result of extremely robust constructed sequences on nanoscale structures, is a key to enhancing the sensing functionality of optical nanosensors. These nanosensor designs can be used as cage probe sinks with reliable control, for the first time, over the colorimetric recognition of cadmium ions to low levels of concentration in the range of 10^–9 to 10^–10 M . Optimization of control sensing conditions is established to achieve enhanced signal response and color intensities. These chemical nanosensors are reversible and have the potential to serve effectively in on‐site field analysis of environmental samples, which eliminates the necessity for instrument‐dependent analysis. Moreover, these new classes of optical cage sensors exhibit long‐term stability of signaling and recognition functionalities that in general provide extraordinary sensitivity, selectivity, reusability, and fast kinetic detection and quantification of various deleterious metal ions in our environment.     

Nanoscale Membrane Strips for Benign Sensing of HgII Ions: A Route to Commercial Waste Treatments

The integration of actively‐functional receptors into nanoscale networks outperformed competent detection devices and other ion‐sensing designs. Synthesis of azo chromophores with long hydrophobic tails showed an ecofriendly sensing and an extreme selectivity for divalent mercury analytes. In order to tailor the tip to Hg^II ion‐sensing functionality, we manipulated the chromophores into nanoscale membrane discs, which led to small, easy‐to‐use optical sensor strips. The design of these hydrophobic probes into ordered pore‐based membranes transformed the ion‐sensing systems into smart, stable assemblies and portable laboratory assays. The nanosensor membrane strips with chemical and mechanical stability allowed for reversible, stable and reusable detectors without any structural damage, even under rigorous chemical treatment for several numbers of repeated cycles. The optical membrane strips provided Hg^II ion‐sensing recognition for both cost‐ and energy‐saving systems. Indeed, the synthetic strips proved to have an efficient ability for various analytical applications, targeting especially for on‐site and in situ chemical analyses, and for continuous monitoring of toxic Hg^II ions. On the proximity‐sensing front, these miniaturized nanomembrane strips can revolutionize the consumer and industrial market with the introduction of the probe surface‐mount naked‐eye ion‐sensor strips.     

Single‐Crystal‐to‐Single‐Crystal Transformation of a Europium(III) Metal–Organic Framework Producing a Multi‐responsive Luminescent Sensor

A sensor with a red‐emission signal is successfully obtained by the solvothermal reaction of Eu³⁺ and heterofunctional ligand bpydbH₂ (4,4′‐(4,4′‐bipyridine‐2,6‐diyl) dibenzoic acid), followed by terminal‐ligand exchange in a single‐crystal‐to‐single‐crystal transformation. As a result of treatments both before and after the metal–organic framework formation, accessible Lewis‐base sites and coordinated water molecules are successfully anchored onto the host material, and they act as signal transmission media for the recognition of analytes at the molecular level. This is the first reported sensor based on a metal–organic framework (MOF) with multi‐responsive optical sensing properties. It is capable of sensing small organic molecules and inorganic ions, and unprecedentedly it can discriminate among the homologues and isomers of aliphatic alcohols as well as detect highly explosive 2,4,6‐trinitrophenol (TNP) in water or in the vapor phase. This work highlights the practical application of luminescent MOFs as sensors, and it paves the way toward other multi‐responsive sensors by demonstrating the incorporation of various functional groups into a single framework.     

Covalent Surface Modification Effects on Single‐Walled Carbon Nanotubes for Targeted Sensing and Optical Imaging

Optical nanoscale technologies often implement covalent or noncovalent strategies for the modification of nanoparticles, whereby both functionalizations are leveraged for multimodal applications but can affect the intrinsic fluorescence of nanoparticles. Specifically, single‐walled carbon nanotubes (SWCNTs) can enable real‐time imaging and cellular delivery; however, the introduction of covalent SWCNT sidewall functionalizations often attenuates SWCNT fluorescence. Recent advances in SWCNT covalent functionalization chemistries preserve the SWCNT's pristine graphitic lattice and intrinsic fluorescence, and here, such covalently functionalized SWCNTs maintain intrinsic fluorescence‐based molecular recognition of neurotransmitter and protein analytes. The covalently modified SWCNT nanosensor preserves its fluorescence response towards its analyte for certain nanosensors, presumably dependent on the intermolecular interactions between SWCNTs or the steric hindrance introduced by the covalent functionalization that hinders noncovalent interactions with the SWCNT surface. These SWCNT nanosensors are further functionalized via their covalent handles with a targeting ligand, biotin, to self‐assemble on passivated microscopy slides, and these dual‐functionalized SWCNT materials are explored for future use in multiplexed sensing and imaging applications.     

Optically Tunable Nonlinearities in Polymers Based on Photoisomerizable Metal‐Based Coordination Complexes

The bottom‐up design of polymer films exhibiting quadratic nonlinear optical properties that can be tuned optically and chemically is described. The polymer matrices are doped with metal‐containing chromophores built around a Zn^II core and photoisomerizable ligands with two different geometries. These molecules possess specifically designed photophysical and nonlinear optical properties to be used towards all‐optical poling, an interference process between one‐ and two‐photon excitations that locally induces macroscopic second‐order effects in polymer films. It is shown that grafting the molecules onto the polymer chains improves the stability of the macroscopic photoinduced nonlinearity in the films.     

3D Microfluidic Surface‐Enhanced Raman Spectroscopy (SERS) Chips Fabricated by All‐Femtosecond‐Laser‐Processing for Real‐Time Sensing of Toxic Substances

A novel all‐femtosecond‐laser‐processing technique is proposed for the fabrication of 2D periodic metal nanostructures inside 3D glass microfluidic channels, which have applications to real‐time surface‐enhanced Raman spectroscopy (SERS). In the present study, 3D glass microfluidic channels are fabricated by femtosecond‐laser‐assisted wet etching. This is followed by the space‐selective formation of Cu‐Ag layered thin films inside the microfluidic structure via femtosecond laser direct writing ablation and electroless metal plating. The Cu‐Ag films are subsequently nanostructured by irradiation with linearly polarized beams to form periodic surface structures. This work demonstrates that a double exposure to laser beams having orthogonal polarization directions can generate arrays of layered Cu‐Ag nanodots with dimensions as small as 25% of the laser wavelength. The resulting SERS microchip is able to detect Rhodamine 6G, exhibiting an enhancement factor of 7.3 × 10⁸ in conjunction with a relative standard deviation of 8.88%. This 3D microfluidic chip is also found to be capable of the real‐time SERS detection of Cd²⁺ ions at concentrations as low as 10 ppb in the presence of crystal violet. This technique shows significant promise for the fabrication of high performance microfluidic SERS platforms for the real‐time sensing of toxic substances with ultrahigh sensitivity.     

Bioinspired Controllable Electro‐Chemomechanical Coloration Films

Coloration materials and devices with broad manipulatable color spectra and precisely controllable capability are highly pursued in various applications, such as camouflage engineering, optical sensors, anticounterfeiting technology, real‐time monitoring, and so on. For achieving the goals, in the present work, a conceptually novel bioinspired coloration film is demonstrated using nanoscale amorphous silicon (a‐Si) layer deposited on a reflective metal substrate. With precisely manipulating the reversible lithiation/delithiation behaviors, such coloration films enable to present consecutively tunable chromogenic property in a broad visible band, since the simultaneous changes in both chemical components and film thickness upon electrochemical processes substantially vary the conditions of destructive interference. Accordingly, the corresponding model based on electro‐chemomechanical coupling effects confirms the coloration mechanism induced by thickness and intrinsic properties (refraction index and optical absorptivity). Additionally, such coloration films also suggest universal design ability, namely tailoring the coloration spectra via simply changing film thicknesses and metal substrates. Thus, the results promise a versatile strategy for fabricating advanced coloration materials and devices that are pursued in specular reflection, sensing, anticounterfeiting, labels, displaying, and sensors.     

Conjugated Polyelectrolyte and Aptamer Based Potassium Assay via Single‐ and Two‐Step Fluorescence Energy Transfer with a Tunable Dynamic Detection Range

A new potassium ion detection assay was developed using a dye‐labeled aptamer and conjugated polyelectrolyte (CPE) as a signaling platform via 1‐step and 2‐step fluorescence resonance energy transfer. Guanine‐rich K⁺‐specific aptamers were designed as K⁺ ion recognition species with 6‐carboxyfluorescein (6‐FAM) and 6‐carboxytetramethylrhodamine (6‐TAMRA) at both termini. In the presence of K⁺ ions, the aptamers undergo a conformational change from an unfolded to folded form by forming a G‐quadruplex with K⁺, bringing two dyes in proximity. FRET‐induced 6‐TAMRA emission was proportional to [K⁺] in a range of 22.5 μm –100 mm in water without interference by the presence of excess Na⁺ ions (100 mm ). Upon the addition of CPE, a two‐step FRET process from CPE to 6‐TAMRA via 6‐FAM was enabled, showing an intensified 6‐TAMRA signal with K⁺ ions. The dynamic detection range and limit of detection (LOD) was fine‐tuned from ～millimolar to ～nanomolar concentrations of K⁺ by modulating the signal amplification effect of CPE. The LOD was determined to be ≈3.0 nm . This detection assay also showed high selectivity against other metal ions. This sensing scheme can be extended to the detection of a wide range of target materials by simply modifying the recognition aptamer sequence.     

Catalytically Doped Semiconductors for Chemical Gas Sensing: Aerogel‐Like Aluminum‐Containing Zinc Oxide Materials Prepared in the Gas Phase

Atmospheric contamination with organic compounds is undesired in industry and in society because of odor nuisance or potential toxicity. Resistive gas sensors made of semiconducting metal oxides are effective in the detection of gases even at low concentration. Major drawbacks are low selectivity and missing sensitivity toward a targeted compound. Acetaldehyde is selected due to its high relevance in chemical industry and its toxic character. Considering the similarity between gas‐sensing and heterogeneous catalysis (surface reactions, activity, selectivity), it is tempting to transfer concepts. A question of importance is how doping and the resulting change in electronic properties of a metal‐oxide support with semiconducting properties alters reactivity of the surfaces and the functionality in gas‐sensing and in heterogeneous catalysis. A gas‐phase synthesis method is employed for aerogel‐like zinc oxide materials with a defined content of aluminum (n‐doping), which were then used for the assembly of gas sensors. It is shown that only Al‐doped ZnO represents an effective sensor material that is sensitive down to very low concentrations (<350 ppb). The advance in properties relates to a catalytic effect for the doped semiconductor nanomaterial.     

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.     

Electrophoretically‐Deposited Metal‐Decorated CNT Nanoforests with High Thermal/Electric Conductivity and Wettability Tunable from Hydrophilic to Superhydrophobic

A single‐step, room‐temperature, and scalable electrophoretic deposition process is reported to form nanocomposites on any electrically conductive surface with metal nanoparticle decorated carbon nanotubes (CNTs). The contact angles (CAs) can be easily tuned from ≈60° to 168° by varying the deposition voltage, while hydrophobicity and superhydrophobicity surprisingly arise from the hydrophilic CNTs being deposited. The relatively high voltage tends to vertically align CNTs during deposition, leading to architectural micro/nanoscale roughness on the surface. The combination of the multiscale roughness along with the low surface energy of hydrocarbon functional groups on the CNT surface has enabled facile wettability control, including the Petal and Lotus effects. Further, the relatively vertical orientation of the CNTs, without any coating, allows for current and heat transfer along their axis with superior conductivity. Similar behavior in terms of CA control is seen for all three divalent metal ions in the deposition solution (i.e., Cu²⁺, Ni²⁺, and Zn²⁺) that are used to charge the CNTs while eventually getting co‐deposited. This implies that this method could possibly be extended to other metals by selecting appropriate charging salt. A patterning technique is also demonstrated for facile fabrication of superhydrophobic CNT‐metal islands surrounded by hydrophilic CNT coating.     

Electrospun Fibers as a Solid‐State Real‐Time Zinc Ion Sensor with High Sensitivity and Cell Medium Compatibility

meso‐2,6‐Dichlorophenyltripyrrinone (TPN‐Cl₂), a probe molecule for zinc II ions, is dispersed in a polymer host. The red fluorescence peak at 620 nm appears when the molecule forms a complex with zinc at its center. TPN‐Cl₂ has a high selectivity for zinc II and tolerates many common metal ions present in the human body. The probe molecules are blended with a hydrogel polymer, poly(2‐hydroxyethyl methacrylate) (poly HEMA), with 30 wt% dimethylformamide (DMF). The fiber structure with 1 μm diameter is made by electrospinning in DMF solution of the probe and poly HEMA mixture. The fibrous film detects zinc ions with concentrations as low as 10^?6 M in real‐time both in water and in the commonly used cell culture liquid media Dulbecco's modified Eagle medium (DMEM) and fetal bovine serum (FBS), which contain many metal ions and proteins. The time‐resolution is 5 min for 10^?6 M and 1 min for 10^?5 M. This sensitivity and response speed satisfy the requirements for non‐invasive biomedical studies.     

Thermo‐Switchable Charge Transport and Electrocatalysis Using Metal‐Ion‐Modified pNIPAM‐Functionalized Electrodes

Metal ions (Ag⁺, Cu²⁺, Hg²⁺) are incorporated into an electropolymerized, poly(N‐isopropyl acrylamide), pNIPAM, thermosensitive polymer associated with an electrode using the “breathing‐in” method. The ion‐functionalized pNIPAM matrices reveal ion‐dependent gel‐to‐solid phase‐transition temperatures (28 ± 1 °C, 25 ± 1 °C, 40 ± 1 °C for the Ag⁺, Cu²⁺, and Hg²⁺‐modified pNIPAM, respectively). Furthermore, the ion‐functionalized polymers exhibit quasi‐reversible redox properties, and the ions are reduced to the respective Ag⁰, Cu⁰, and Hg⁰ nanocluster‐modified polymers. The metal‐nanocluster‐functionalized pNIPAM matrices enhance the electron transfer (they exhibit lower electron‐transfer resistances) in the compacted states. The electron‐transfer resistances of the metal‐nanocluster‐modified pNIPAM can be cycled between low and high values by temperature‐induced switching of the polymer between its contracted solid and expanded gel states, respectively. The enhanced electron‐transfer properties of the metal nanocluster‐functionalized polymer are attributed to the contacting of the metal nanoclusters in the contracted state of the polymers. This temperature‐switchable electron transfer across a Ag⁰‐modified pNIPAM was implemented to design a thermo‐switchable electrocatalytic process (the temperature‐switchable electrocatalyzed reduction of H₂O₂ by Ag⁰‐pNIPAM).     

Optimized Colorimetric Photonic‐Crystal Humidity Sensor Fabricated Using Glancing Angle Deposition

Colorimetric sensing, where environmental changes are transduced into visual color changes, provides an intuitively simple yet powerful detection mechanism that is well‐suited to the realization of low‐cost and low‐power sensors. A new approach in colorimetric sensing exploits the structural colour of photonic crystals (PCs) to create new color‐changing materials, however much work is still required to simultaneously achieve optimized sensor response and low‐cost, scalable nanofabrication. This work responds to these challenges by designing, fabricating and evaluating a mesoporous PC sensor optimized to exhibit as large as possible color‐shift in response to small changes in relative humidity (RH). A novel design optimization is achieved by employing a colorimetric framework that translates simulated/measured spectral quantities into numeric color values directly related to color perception. The sensor design is then realized using a mesoporous TiO₂ PC, fabricated using glancing angle deposition (GLAD). The GLAD technique is a bottom‐up, single‐step nanofabrication method providing the nanoscale precision required to successfully realize the optimized PC design. The PC sensor is shown to be highly sensitive and stable: the PC structural‐color changes visibly due to RH changes smaller than 1%, and the response is stable over hundreds of hours of sensor operation. Additionally, measurements and simulations are used to reveal the important link between the PC optical modes, pore geometry, and sensor response which will be useful in future PC sensor experiments. The combination of bottom‐up nanofabrication with visible color‐based sensing, coupled with the useful design methodology, will lead to further developments in low‐cost, widely deployable optical sensors.     

Layer‐Structured Photoconducting Polymers: A New Class of Photorefractive Materials

We study the photorefractive (PR) properties of a new kind of low glass‐transition temperature (T_g) polymer composite based on layered photoconductive polymers, poly(p‐phenylene terephthalate) carbazoles (PPT‐CZs). These photoconductors consist of the rigid backbone of PPT with pendant oxyalkyl CZ groups. The compounds are doped with the photosensitizer C₆₀ and nonlinear optical chromophores diethylaminodicyanostyrene (DDCST), and no plasticizers are added. When the host polymers are mixed with various PR ingredients, the layers are preserved and their layer distance increases, indicating that all the guest molecules are confined to the nanoscale interlayer space. These composites showed very low T_g values (< ? °C). Despite the absence of a plasticizer and the lower concentration of the carbazole photoconductive moieties as compared to poly(N‐vinylcarbazole) systems, these materials show excellent PR properties, i.e., a PR gain of Γ = 250 cm^–1 under an external electric field of 60 V μm^–1, and diffraction efficiency and PR sensitivity of 93 % and 24 ± 7 cm² kJ^–1 at E = 100 V μm^–1, respectively.     

Multiarray Nanopattern Electronic Nose (E‐Nose) by High‐Resolution Top‐Down Nanolithography

An electronic nose (E‐nose) is an artificial sensing device that mimics the human olfactory system using a multiarray sensor system. However, since the design and fabrication of multiarray sensing channels are significantly limited because of the requirement of time‐consuming and nonuniversal processes, the development of commercializable and high‐throughput fabrication approaches are critically required. Herein, high‐resolution top‐down lithography is developed for E‐nose fabrication for the first time. Five different metal oxide semiconductor (MOS) nanopattern channels (NiO, CuO, Cr₂O₃, SnO₂, and WO₃) are fabricated into multiarray sensors with high‐throughput using a unique lithographic approach that utilizes the sputtering of grains of the metals via low‐energy ion plasma bombardment. The nanopattern channels show i) high‐resolutions (15 nm scale), ii) high‐aspect‐ratios (11; 14 nm width and 150 nm height), and iii) ultrasmall grains (5.1 nm) with uniformity on a cm² scale, resulting in high sensitivity toward the target analytes. The E‐nose system, which is composed of five MOS nanopattern channels, can successfully distinguish seven different hazardous analytes, including volatile organic compounds and nitrogen‐containing compounds. It is expected that this unique lithography approach can provide a simple and reliable method for commercializable channel fabrication, and the E‐noses can have further applications in real‐life situations.     

Hydrogen Adsorption in Metal–Organic Frameworks: Cu‐MOFs and Zn‐MOFs Compared

Hydrogen adsorption in two different metal–organic frameworks (MOFs), MOF‐5 and Cu‐BTC (BTC: benzene‐1,3,5‐tricarboxylate), with Zn²⁺ and Cu²⁺ as central metal ions, respectively, is investigated at temperatures ranging from 77 K to room temperature. The process responsible for hydrogen storage in these MOFs is pure physical adsorption with a heat of adsorption of approximately –4 kJ mol^–1. With a saturation value of 5.1 wt.‐% for the hydrogen uptake at high pressures and 77 K, MOF‐5 shows the highest storage capacity ever reported for crystalline microporous materials. However, at low pressures Cu‐BTC shows a higher hydrogen uptake than MOF‐5, making Cu‐based MOFs more promising candidates for potential storage materials. Furthermore, the hydrogen uptake is correlated with the specific surface area for crystalline microporous materials, as shown for MOFs and zeolites.     

Toward Sensitive Room‐Temperature Broadband Detection from Infrared to Terahertz with Antenna‐Integrated Black Phosphorus Photoconductor

Graphene‐like two‐dimensional materials (graphene, transition‐metal dichalcogenides (TMDCs)) have received extraordinary attention owing to their rich physics and potential applications in building nanoelectronic and nanophotonic devices. Recent works have concentrated on increasing the responsivity and extending the operation range to longer wavelengths. However, the weak absorption of gapless graphene, and the large bandgap (>1 eV) and low mobility in TMDCs have limited their spectral usage to only a narrow range in the visible spectrum. In this work, we demonstrate for the first time a high‐performance, antenna‐integrated, black phosphorus (BP)‐based photoconductor with ultra‐broadband detection from the infrared to terahertz frequencies. The good trade‐off between the moderate bandgap and good mobility results in a broad spectral absorption that is superior to that of graphene. Different photoconductive mechanisms, such as photothermoelectric (PTE), bolometric, and electron–hole generation can be distinguished depending on the device geometry, incident wavelength, and power. Especially, the photoconductive response remains highly efficient, even when the photon energy is extended to the terahertz (THz) band at room temperature, which is driven by the thermoelectric‐induced well. The proposed photodetectors have a superior performance with an excellent sensitivity of over 300 V W^?1, low noise equivalent power (NEP) (smaller than 1 nW Hz^?0.5 (10 pW Hz^?0.5) with respect to the incident (absorbed) power), and fast response, all of which play key roles in multispectral biological imaging, remote sensing, and optical communications.     

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.     

Biocatalytic Nanoscale Coatings Through Biomimetic Layer‐by‐Layer Mineralization

Recent insight into the molecular mechanisms of biological mineral formation (biomineralization) has enabled biomimetic approaches for the synthesis of functional organic‐inorganic hybrid materials under mild reaction conditions. Here we describe a novel method for enzyme immobilization in thin (nanoscale) conformal mineral coatings using biomimetic layer‐by‐layer (LbL) mineralization. The method utilizes a multifunctional molecule comprised of a naturally‐occurring peptide, protamine (PA), covalently bound to the redox enzyme Glucose oxidase (GOx). PA mimics the mineralizing properties of biomolecules involved in silica biomineralization in diatoms, and its covalent attachment to GOx does not interfere with the catalytic activity. Highly efficient and stable incorporation of this modified enzyme (GOx‐PA) into nanoscale layers (～5–7 nm thickness) of Ti‐O and Si‐O is accomplished during protamine‐enabled LbL mineralization on silica spheres. Depending on the layer location of the enzyme and the type of mineral (silica or titania) within which the enzyme is incorporated, the resulting multilayer biocatalytic hybrid materials exhibit between 20–100% of the activity of the free enzyme in solution. Analyses of kinetic properties (V_max, K_M) of the immobilized enzyme, coupled with characterization of physical properties of the mineral‐bearing layers (thickness, porosity, pore size distribution), indicates that the catalytic activities of the synthesized hybrid nanoscale coatings are largely determined by substrate diffusion rather than enzyme functionality. The GOx‐PA immobilized in these nanoscale layers is substantially stabilized against heat‐induced denaturation and largely protected from proteolytic attack. The method for enzyme immobilization described here enables, for the first time, the high yield immobilization and stabilization of enzymes within continuous, conformal, and nanoscale coatings through biomimetic LbL mineralization. This approach will likely be applicable to a wide variety of surfaces and functional biomolecules. The ability to synthesize thin (nanoscale) conformal enzyme‐loaded layers is of interest for numerous applications, including enzyme‐based biofuel cells and biosensors.