Janus Au-mesoporous silica nanoparticles as electrochemical biorecognition-signaling system

Proteases immobilized on nanomaterials for biocatalytic, environmental and biomedical applications: Advantages and drawbacks

Proteases have gained significant scientific and industrial interest due to their unique biocatalytic characteristics and broad-spectrum applications in different industries. The development of robust nanobiocatalytic systems by attaching proteases onto various nanostructured materials as fascinating and novel nanocarriers has demonstrated exceptional biocatalytic performance, substantial stability, and ease of recyclability over multiple reaction cycles under different chemical and physical conditions. Proteases immobilized on nanocarriers may be much more resistant to denaturation caused by extreme temperatures or pH values, detergents, organic solvents, and other protein denaturants than free enzymes. Immobilized proteases may present a lower inhibition. The use of non-porous materials in the immobilization prevents diffusion and steric hindrances during the binding of the substrate to the active sites of enzymes compared to immobilization onto porous materials; when using very large or solid substrates, orientation of the enzyme must always be adequate. The advantages and problems of the immobilization of proteases on nanoparticles are discussed in this review. The continuous and batch reactor operations of nanocarrier-immobilized proteases have been successfully investigated for a variety of applications in the leather, detergent, biomedical, food, and pharmaceutical industries. Information about immobilized proteases on various nanocarriers and nanomaterials has been systematically compiled here. Furthermore, different industrial applications of immobilized proteases have also been highlighted in this review.

Electrochemical immunoassay for one-pot detection of thyroxin (T4) and thyroid-stimulating hormone (TSH) using magnetic and Janus nanoparticles

Concurrent measurement of thyroid-stimulating hormone (TSH) and thyroxine (T4) hormones profoundly help clinicians diagnose hyper- and hypothyroidism. This work demonstrates the development of a sandwich-type electrochemical immunoassay using Janus and magnetic nanoparticles for one-pot detection of thyroxine (T4) and thyroid-stimulating hormone (TSH). The signaling probe was developed by preparing Janus cadmium (CdO) and zinc oxide (ZnO) NPs decorated by T4/TSH-specific molecularly imprinted polymers (MIP_T4-CdO and MIP_TSH-ZnO). The capture probe was obtained by coating magnetic Fe₃O₄ NPs with 1,3-Bis(3-carboxy propyl) tetramethyl disiloxane and activating using N-hydroxy succinimide (NHS) and 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC), and finally conjugating with T4/TSH-specific antibodies. To analyze T4 and TSH in actual samples, MIP_T4-CdO and MIP_TSH-ZnO were added to the sample solutions, and after incubation, capture probes (Fe₃O₄-Ab_TSH and Fe₃O₄-Ab_T4) were added. An external magnetic field was used to separate the sandwiched nanosystem, followed by adding a dilute solution of nitric acid (HNO₃) to dissolve CdO and ZnO NPs and free Cd(II) and Zn(II) cations. The concentration of these cations was determined using constant-current potentiometric stripping analysis (cc-PSA) on screen-printed electrodes (SPE) modified with multi-walled carbon nanotubes (MWCNT). The obtained signals for Cd(II) and Zn(II) were proportional to T4 and TSH concentrations. Limits of detection (LOD) for T4 and TSH analyses were respectively 0.02 ng.dL^-1 and 0.0002 µU.mL^-1 with a linear range of 0.05-50 ng.dL^-1 and 0.001-100 µU.mL^-1. The proposed nanosystem's main advantage is the simultaneous detection of T4 and TSH in clinical samples with high sensitivity, selectivity, and stability.

Application of Janus Particles in Point-of-Care Testing

Janus particles (JPs), named after the two-faced Roman god, are asymmetric particles with different chemical properties or polarities. JPs have been widely used in the biomedical field in recent years, including as drug carriers for targeted controlled drug release and as biosensors for biological imaging and biomarker detection, which is crucial in the early detection and treatment of diseases. In this review, we highlight the most recent advancements made with regard to Janus particles in point-of-care testing (POCT). Firstly, we introduce several commonly used methods for preparing Janus particles. Secondly, we present biomarker detection using JPs based on various detection methods to achieve the goal of POCT. Finally, we discuss the challenges and opportunities for developing Janus particles in POCT. This review will facilitate the development of POCT biosensing devices based on the unique properties of Janus particles.

Electrochemical aptasensor based on anisotropically modified (Janus-type) gold nanoparticles for determination of C-reactive protein

Novel Janus nanoparticles based on Au colloids anisotropically modified with polyamidoamine dendrons were prepared though a masking/toposelective modification approach. These nanomaterials were further functionalized with horseradish peroxidase on the dendritic face and provided on the opposite metal surface with a ssDNA aptamer for C-reactive protein (CRP). The resulting nanoparticles were employed as biorecognition/signaling elements to construct an amperometric aptasensor with sandwich-type architecture for the specific detection of this cardiac biomarker. To do this, screen-printed carbon electrodes modified with electrodeposited Au nanoparticles and functionalized with anti-CRP aptamers were used as transduction interface. The aptasensor was employed for the amperometric detection of CRP (working potential: - 200 mV vs pseudo-Ag/AgCl) in the broad range from 10 pg·mL^-1 to 1.0 ng·mL^-1 with a detection limit of 3.1 pg·mL^-1. This electroanalytical device also showed good specificity, reproducibility (RSD = 9.8%, n = 10), and stability and was useful to quantify CRP in reconstituted human serum samples, with a RSD of 13.3%.

A glutathione disulfide-sensitive Janus nanomachine controlled by an enzymatic AND logic gate for smart delivery

This work describes the assembly of a novel enzyme-controlled nanomachine operated through an AND Boolean logic gate for on-command delivery. The nanodevice was constructed on Au-mesoporous silica Janus nanoparticles capped with a thiol-sensitive gate-like molecular ensemble on the mesoporous face and functionalized with glutathione reductase on the gold face. This autonomous nanomachine employed NADPH and glutathione disulfide as input chemical signals, leading to the enzymatic production of reduced glutathione that causes the disruption of the gating mechanism on the mesoporous face and the consequent payload release as an output signal. The nanodevice was successfully used for the autonomous release of doxorubicin in HeLa cancer cells and RAW 264.7 macrophage cells.

Janus particles and motors: unrivaled devices for mastering (bio)sensing

Janus particles are a unique type of materials combining two different functionalities in a single unit. This allows the combination of different analytical properties leading to new analytical capabilities, i.e., enhanced fluid mixing to increase sensitivity with targeting capturing abilities and unique advantages in terms of multi-functionality and versatility of modification, use, and operation both in static and dynamic modes. The aim of this conceptual review is to cover recent (over the last 5 years) advances in the use of Janus microparticles and micromotors in (bio)-sensing. First, the role of different materials and synthetic routes in the performance of Janus particles are described. In a second main section, electrochemical and optical biosensing based on Janus particles and motors are covered, including in vivo and in vitro methodologies as the next biosensing generation. Current challenges and future perspectives are provided in the conclusions section.

Janus Nanoparticles: From Fabrication to (Bio)Applications

Janus nanoparticles (JNPs) refer to the integration of two or more chemically discrepant composites into one structure system. Studies into JNPs have been of significant interest due to their interesting characteristics stemming from their asymmetric structures, which can integrate different functional properties and perform more synergetic functions simultaneously. Herein, we present recent progress of Janus particles, comprehensively detailing fabrication strategies and applications. First, the classification of JNPs is divided into three blocks, consisting of polymeric composites, inorganic composites, and hybrid polymeric/inorganic JNPs composites. Then, the fabrication strategies are alternately summarized, examining self-assembly strategy, phase separation strategy, seed-mediated polymerization, microfluidic preparation strategy, nucleation growth methods, and masking methods. Finally, various intriguing applications of JNPs are presented, including solid surfactants agents, micro/nanomotors, and biomedical applications such as biosensing, controlled drug delivery, bioimaging, cancer therapy, and combined theranostics. Furthermore, challenges and future works in this field are provided.

Multimodal/Multifunctional Nanomaterials in (Bio)electrochemistry: Now and in the Coming Decade

Multifunctional nanomaterials, defined as those able to achieve a combined effect or more than one function through their multiple functionalization or combination with other materials, are gaining increasing attention in the last years in many relevant fields, including cargo targeted delivery, tissue engineering, in vitro and/or in vivo diseases imaging and therapy, as well as in the development of electrochemical (bio)sensors and (bio)sensing strategies with improved performance. This review article aims to provide an updated overview of the important advances and future opportunities exhibited by electrochemical biosensing in connection to multifunctional nanomaterials. Accordingly, representative aspects of recent approaches involving metal, carbon, and silica-based multifunctional nanomaterials are selected and critically discussed, as they are the most widely used multifunctional nanomaterials imparting unique capabilities in (bio)electroanalysis. A brief overview of the main remaining challenges and future perspectives in the field is also provided.

Nanoarchitecting Hierarchical Mesoporous Siliceous Frameworks: A New Way Forward

Owing to their attractive physicochemical and morphological attributes, mesoporous silica nanoparticles (MSNs) have attracted increasing attention over the past two decades for their utilization in diversified fields. Despite the success, these highly stable siliceous frameworks often suffer from several shortcomings of compatibility issues, uncontrollable degradability leading to long-term retention in vivo, and substantial unpredictable toxicity risks, as well as deprived drug encapsulation efficiency, which could limit their applicability in medicine. Along this line, various advancements have been made in re-engineering the stable siliceous frameworks, such as the incorporation of diverse molecular organic, as well as inorganic (cationic and anionic) species and monitoring the processing, as well as formulation parameters, resulting in the hetero-nanostructures of irregular-shaped (Janus and multi-podal) and dynamically-modulated (deformable solids) architectures with high morphological complexity. Insightfully, this review gives a brief emphasis on re-engineering such stable siliceous frameworks through modifying their intrinsic structural and physicochemical attributes. In conclusion, we recapitulate the review with exciting perspectives.

Janus nanocarrier powered by bi-enzymatic cascade system for smart delivery

We report herein the assembly of an integrated nanodevice with bi-enzymatic cascade control for on-command cargo release. This nanocarrier is based on Au-mesoporous silica Janus nanoparticles capped at the mesoporous face with benzimidazole/β-cyclodextrin-glucose oxidase pH-sensitive gate-like ensembles and functionalized with invertase on the gold face. The rationale for this delivery mechanism is based on the invertase-mediated hydrolysis of sucrose yielding glucose, which is further transformed into gluconic acid by glucose oxidase causing the disruption of the pH-sensitive supramolecular gates at the Janus nanoparticles. This enzyme-powered device was successfully employed in the autonomous and on-demand delivery of doxorubicin in HeLa cancer cells.

An enzyme-controlled Janus nanomachine for on-command dual and sequential release

A novel multi-stimuli responsive Janus nanomachine with enzymatic control for dual and sequential release of two different payloads was developed.

Biosensing and Delivery of Nucleic Acids Involving Selected Well-Known and Rising Star Functional Nanomaterials

In the last fifteen years, the nucleic acid biosensors and delivery area has seen a breakthrough due to the interrelation between the recognition of nucleic acid's high specificity, the great sensitivity of electrochemical and optical transduction and the unprecedented opportunities imparted by nanotechnology. Advances in this area have demonstrated that the assembly of nanoscaled materials allows the performance enhancement, particularly in terms of sensitivity and response time, of functional nucleic acids' biosensing and delivery to a level suitable for the construction of point-of-care diagnostic tools. Consequently, this has propelled detection methods using nanomaterials to the vanguard of the biosensing and delivery research fields. This review overviews the striking advancement in functional nanomaterials' assisted biosensing and delivery of nucleic acids. We highlight the advantages demonstrated by selected well-known and rising star functional nanomaterials (metallic, magnetic and Janus nanomaterials) focusing on the literature produced in the past five years.

Amperometric aptasensor for carcinoembryonic antigen based on the use of bifunctionalized Janus nanoparticles as biorecognition-signaling element

We report herein the design of a novel biosensing strategy for the detection of carcinoembryonic antigen (CEA), based on the use of Janus-type nanoparticles having Au and silica opposite faces as integrated electrochemical biorecognition-signaling system. The Janus nanoparticles were properly functionalized with horseradish peroxidase on the silica surface to act as signaling element, and a biotin thiol-modified anti-CEA DNA hairpin aptamer the Au face to assemble the biorecognition element. The sensing approach relies on the first specific recognition of CEA by the bifunctionalized Janus nanoparticles, causing unfolding of the DNA hairpin structure and unmasking the biotin residues at the aptamer chain. This CEA-Janus nanoparticle complex was then captured by avidin-modified Fe₃O₄@SiO₂ NanoCaptors^®, allowing further magnetic deposition on carbon screen printed electrodes for the amperometric detection of the cancer biomarker. The Janus nanoparticles-based aptasensor was able to detect CEA in the range from 1 to 5000 ng mL^-1 (5.5 pM-28 nM) with a detection limit of 210 pg mL^-1 (1.2 pM). The aptasensor also showed high reproducibility and storage stability, and was successfully validated in human serum.

A Label-free aptasensor based on Aptamer/NH2 Janus particles for ultrasensitive electrochemical detection of Ochratoxin A

In this study, a novel aptasensor based on Aptamer/NH₂ Janus particles is developed for the detection of Ochratoxin A(OTA). By coating gold on the hemispherical surface of the aminated polystyrene particles, Ochratoxin A aptamer is immobilized on the surface of the gold layer for selective identification and the other hemispherical able to bind to Glassy carbon electrode via peptide bond. Under optimum conditions, the sensor exhibited a wide dynamic range of OTA concentration from 1 × 10^-5 nM to 10 nM, and the detection limit is 3.3 × 10^-3 pM on condition of acceptable stability and reproducibility. The sensors were showed excellent performance in the detection of OTA in red wine sample with recoveries between 95.7% and 100.18%, which studied by the standard addition spiking technique. This work provides a new idea and method for preparing immune electrochemical sensors and is expected to be used for the OTA detection in red wine sample analysis.

Interactive models of communication at the nanoscale using nanoparticles that talk to one another

‘Communication' between abiotic nanoscale chemical systems is an almost-unexplored field with enormous potential. Here we show the design and preparation of a chemical communication system based on enzyme-powered Janus nanoparticles, which mimics an interactive model of communication. Cargo delivery from one nanoparticle is governed by the biunivocal communication with another nanoparticle, which involves two enzymatic processes and the interchange of chemical messengers. The conceptual idea of establishing communication between nanodevices opens the opportunity to develop complex nanoscale systems capable of sharing information and cooperating.

In the interactive model of communication, information is exchanged bidirectionally between a sender and receiver. Here, the authors realise interactive communication between two artificial nanoparticles, which relay information between each other in the form of chemical messengers and enzymatic reactions.

Au–Mesoporous silica nanoparticles gated with disulfide-linked oligo(ethylene glycol) chains for tunable cargo delivery mediated by an integrated enzymatic control unit

Acetylcholinesterase-functionalized Au–mesoporous silica capped with a thiol-responsive gate is reported.

Introducing asymmetric functionality into MOFs via the generation of metallic Janus MOF particles

Herein we report a versatile methodology for engineering metallic Janus MOF particles based on desymmetrization at interfaces, whereby each MOF particle is partially coated with a desired metal. We demonstrate that it enables the fabrication of homogeneous Janus MOF particles according to the MOF (ZIF-8, UiO-66 or UiO-66-SH), the metal (Au, Co or Pt), the MOF particle size (from the micrometer to the submicrometer regime) and the metal-film thickness (from 5 nm to 50 nm) employed. We anticipate that our strategy could be applied to impart new functionalities to MOFs, including asymmetric functionalization, magnetic-guidance and motorization.

Toward the design of smart delivery systems controlled by integrated enzyme-based biocomputing ensembles

We report herein the design of a smart delivery system in which cargo delivery from capped mesoporous silica (MS) nanoparticles is controlled by an integrated enzyme-based "control unit". The system consists of Janus-type nanoparticles having opposing Au and MS faces, functionalized with a pH-responsive β-cyclodextrin-based supramolecular nanovalve on the MS surface and two effectors, glucose oxidase and esterase, immobilized on the Au face. The nanodevice behaves as an enzymatic logical OR operator which is selectively fueled by the presence of D-glucose and ethyl butyrate.

Label and indicator free electrochemical nanobiosensing of DNA hybridization based on MnO2 nanomaterial modified GCPE

A label and indicator free electrochemical DNA hybridization detection method based on MnO₂-Nps/GCPE was developed. Compared to plain GCPE, a very robust and sensitive genosensor was obtained.