Rapid determination of SARS-CoV-2 nucleocapsid proteins based on 2D/2D MXene/P–BiOCl/Ru(bpy)32+ heterojunction composites to enhance electrochemiluminescence performance

Emerging trends and recent advances in MXene/MXene-based nanocomposites toward electrochemiluminescence sensing and biosensing

Electrochemiluminescence (ECL) sensing systems have surged in popularity in recent years, making significant strides in sensing and biosensing applications. The realization of high-throughput ECL sensors hinges on the implementation of novel signal amplification strategies, propelling the field toward a new era of ultrasensitive analysis. A key strategy for developing advanced ECL sensors and biosensors involves utilizing novel structures with remarkable properties. The past few years have witnessed the emergence of MXenes as a captivating class of 2D materials, with their unique properties leading to exploitation in diverse applications. This review provides a comprehensive summary of the latest advancements in MXene-modified materials specifically engineered for ECL sensing and biosensing applications. We thoroughly analyze the structure, surface functionalization, and intrinsic properties of MXenes that render them exceptionally suitable candidates for the development of highly sensitive ECL sensors and biosensors. Furthermore, this study explores the broad spectrum of applications of MXenes in ECL sensing, detailing their multifaceted roles in enhancing the performance and sensitivity of ECL (bio)sensors. By providing a comprehensive overview, this review is expected to promote progress in related areas.

Nanomaterials revolutionize biosensing: 0D-3D designs for ultrasensitive detection of microorganisms and viruses

Various diseases caused by harmful microorganisms and viruses have caused serious harm and huge economic losses to society. Thus, rapid detection of harmful microorganisms and viruses is necessary for disease prevention and treatment. Nanomaterials have unique properties that other materials do not possess, such as a small size effect and quantum size effect. Introducing nanomaterials into biosensors improves the performance of biosensors for faster and more accurate detection of microorganisms and viruses. This review aims to introduce the different kinds of biosensors and the latest advances in the application of nanomaterials in biosensors. In particular, this review focuses on describing the physicochemical properties of zero-, one-, two-, and three-dimensional nanostructures as well as nanoenzymes. Finally, this review discusses the applications of nanobiosensors in the detection of microorganisms and viruses and the future directions of nanobiosensors.

Multiple signal-enhanced electrochemiluminescence aptamer sensors based on carboxylated ruthenium (II) complexes for acetamiprid detection

BACKGROUND

Rapid and sensitive detection for acetamiprid, a kind of widely used neonicotinoid insecticide, is very meaningful for the development of modern agriculture and the protection of human health. Highly stable electrochemiluminescence (ECL) materials are one of the key factors in ECL sensing technology. ECL materials prepared by porous materials (e.g., MOFs) coated with chromophores have been used for ECL sensing detection, but these materials have poor stability because the chromophores escape when they are in aqueous solution. Therefore, the development of highly stable ECL materials is of great significance to improve the sensitivity of ECL sensing technology.

RESULTS

In this work, by combining etched metal-organic frameworks (E-UIO-66-NH2) as carrier with Tris(4,4'-dicarboxylic acid-2,2'-bipyridine)Ru(II) chloride (Ru(dcbpy)32+) as signal probe via amide bonds, highly stable nanocomposites (E-UIO-66-NH2-Ru) with excellent ECL performance were firstly prepared. Then, using MoS2 loaded with AuNPs as substrate material and co-reactant promoter, a signal off-on-off ECL aptamer sensor was prepared for sensitive detection of acetamiprid. Due to the excellent catalytic activity of E-UIO-66-NH2-Ru and MoS2@Au towards K2S2O8, the ECL signals can be enhanced by multiple signal enhancement pathways, the prepared ECL aptamer sensor could achieve sensitive detection of acetamiprid in the linear range of 10-13 to10-7 mol L-1, with the limit of detection (LOD) of 2.78ⅹ10-15 mol L-1 (S/N = 3). After the evaluation of actual sample testing, this sensing platform was proven to be an effective method for the detection of acetamiprid in food and agricultural products.

SIGNIFICANCE AND NOVELTY

The E-UIO-66-NH2-Ru prepared by linking Ru(dcbpy)32+ to E-UIO-66-NH2 via amide bonding has very high stability. The synergistic catalytic effect of MoS2 and AuNPs enhanced the ECL signal. By exploring the sensing mechanism and evaluating the actual sample tests, the proposed signal "on-off" ECL sensing strategy was proved to be an effective and excellent ECL sensing method for sensitive and stable detection of acetamiprid.

Engineered two-dimensional nanomaterials based diagnostics integrated with internet of medical things (IoMT) for COVID-19

More than four years have passed since an inimitable coronavirus disease (COVID-19) pandemic hit the globe in 2019 after an uncontrolled transmission of the severe acute respiratory syndrome (SARS-CoV-2) infection. The occurrence of this highly contagious respiratory infectious disease led to chaos and mortality all over the world. The peak paradigm shift of the researchers was inclined towards the accurate and rapid detection of diseases. Since 2019, there has been a boost in the diagnostics of COVID-19 via numerous conventional diagnostic tools like RT-PCR, ELISA, etc., and advanced biosensing kits like LFIA, etc. For the same reason, the use of nanotechnology and two-dimensional nanomaterials (2DNMs) has aided in the fabrication of efficient diagnostic tools to combat COVID-19. This article discusses the engineering techniques utilized for fabricating chemically active E2DNMs that are exceptionally thin and irregular. The techniques encompass the introduction of heteroatoms, intercalation of ions, and the design of strain and defects. E2DNMs possess unique characteristics, including a substantial surface area and controllable electrical, optical, and bioactive properties. These characteristics enable the development of sophisticated diagnostic platforms for real-time biosensors with exceptional sensitivity in detecting SARS-CoV-2. Integrating the Internet of Medical Things (IoMT) with these E2DNMs-based advanced diagnostics has led to the development of portable, real-time, scalable, more accurate, and cost-effective SARS-CoV-2 diagnostic platforms. These diagnostic platforms have the potential to revolutionize SARS-CoV-2 diagnosis by making it faster, easier, and more accessible to people worldwide, thus making them ideal for resource-limited settings. These advanced IoMT diagnostic platforms may help with combating SARS-CoV-2 as well as tracking and predicting the spread of future pandemics, ultimately saving lives and mitigating their impact on global health systems.

Advances in MXene-based luminescence sensing strategies

MXenes have attracted the attention of many researchers as one of the latest two-dimensional (2D) materials over the last decade. Their great potential for biosensing has also been fully exploited after the discovery of their unique properties such as superior optical properties, excellent hydrophilicity, good thermal stability, excellent mechanical property, high electrical conductivity, biocompatibility, large surface area, and ease of surface functionalization. In the MXene-based luminescence sensing strategy, MXenes typically appear in the form of nanosheets, quantum dots and modified MXene nanocomposites, and they are utilized as different sensing platforms or as a luminescence source. In this review, we focused on the MXene-based luminescence sensing strategies, including fluorescence, electrochemiluminescence and chemiluminescence sensors and the comparison of their performance. Finally, the perspectives of the MXene-based luminescence sensors are discussed.

Promoting effect of TiVC MXene on cathodic electrogenerated chemiluminescence of Ru(bpy)32+ and its application in the sensitive detection of sulfite

The enhanced cathodic ECL of Ru(bpy)32+ at a bimetallic element MXenes (TiVC MXene) modified electrode in neutral aqueous condition is reported. TiVC MXene significantly catalyzed the oxygen reduction reaction (ORR) as well as the electrochemical reduction of Ru(bpy)32+ to produce reactive oxygen species and Ru(bpy)3+. The obtained hydroxyl radical (OH∙) not only oxidized Ru(bpy)3+ to generate Ru(bpy)32+* and emit light through coreactant pathway, but also oxidized Ru(bpy)32+ to Ru(bpy)33+, which caused an annihilation ECL reaction. As a result, two pathways occurred simultaneously to generate strong cathodic ECL signal. Sulfite removes the dissolved oxygen in water and reduces the occurrence of ORR, which prohibits the generation of OH∙ to decrease the ECL signal. The decrement of ECL intensity varied linearly with the concentration of sulfite in the range 2 nM to 50 μM with a detection limit of 0.14 nM (3σ). The proposed sensor exhibited good analytical performance, and could be used in the detection of sulfite in real samples. The results revealed that the electrocatalytic behavior of TiVC MXene is the key factor for strong cathodic Ru(bpy)32+ ECL, which provides new application in ECL sensing field.

Hierarchical Nanobiosensors at the End of the SARS-CoV-2 Pandemic

Nanostructures have played a key role in the development of different techniques to attack severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Some applications include masks, vaccines, and biosensors. The latter are of great interest for detecting diseases since some of their features allowed us to find specific markers in secretion samples such as saliva, blood, and even tears. Herein, we highlight how hierarchical nanoparticles integrated into two or more low-dimensional materials present outstanding advantages that are attractive for photonic biosensing using their nanoscale functions. The potential of nanohybrids with their superlative mechanical characteristics together with their optical and optoelectronic properties is discussed. The progress in the scientific research focused on using nanoparticles for biosensing a variety of viruses has become a medical milestone in recent years, and has laid the groundwork for future disease treatments. This perspective analyzes the crucial information about the use of hierarchical nanostructures in biosensing for the prevention, treatment, and mitigation of SARS-CoV-2 effects.

Development of a label-free impedimetric aptasensor based on Zr-MOF and titaniom carbide nanosheets for detection of L-tryptophan

This study primarily focuses on the L-Tryptophan (Trp) biomarker assay, with particular attention given to its objectives. The investigation centers on the potential implications of imbalanced Trp levels and its associated metabolites, which have been attributed to the spectrum of both psychological and physiological disorders, encompassing conditions such as cancer. Therefore, the swift and accurate detection of this amino acid is of paramount importance in cancer monitoring, as it plays a crucial role in preventing the metastasis and spread of cancer cells. Thus, an electrochemical aptasensor was designed based on nanocomposite of AgNPs@UiO-66/Ti3C2 (MXene) as immobilization strategy for the ultrasensitive detection of Trp. Zirconium metal-organic frameworks (Zr-MOFs) were employed as carriers for silver nanoparticles to facilitate subsequent binding with aptamers. Markedly, the obtained results show that the constructed aptasensor can specifically detect Trp in the two concentration range from 1fM to 1 nM and 1 nM to 200 nM and with a low detection limit of 0.35 fM. When applied to real samples, the experimental results demonstrated positive recovery rates. Consequently, a discerning and sensitive electrochemical aptasensor devoid of labeling agents was successfully fabricated for the explicit purpose of Trp detection.

MXene-based electrochemical devices applied for healthcare applications

The initial part of the review provides an extensive overview about MXenes as novel and exciting 2D nanomaterials describing their basic physico-chemical features, methods of their synthesis, and possible interfacial modifications and techniques, which could be applied to the characterization of MXenes. Unique physico-chemical parameters of MXenes make them attractive for many practical applications, which are shortly discussed. Use of MXenes for healthcare applications is a hot scientific discipline which is discussed in detail. The article focuses on determination of low molecular weight analytes (metabolites), high molecular weight analytes (DNA/RNA and proteins), or even cells, exosomes, and viruses detected using electrochemical sensors and biosensors. Separate chapters are provided to show the potential of MXene-based devices for determination of cancer biomarkers and as wearable sensors and biosensors for monitoring of a wide range of human activities.

Electrochemiluminescence resonance energy transfer between a Ru-ZnMOF self-enhanced luminophore and a double quencher ZnONF@PDA to detect NSE

The construction of advanced systems capable of accurately detecting neuron-specific enolase (NSE) is essential for rapidly diagnosing small-cell lung cancer. In this study, an electrochemiluminescence (ECL) resonance energy transfer immunosensor was proposed for the ultra-sensitive detection of NSE. The co-reactants C2O42- and Ru(bpy)32+ were integrated to form a self-enhanced ECL luminophore (Ru-ZnMOF) as the ECL donor. The abundant carboxyl functional groups of Ru-ZnMOF supported antibody 1 via an amidation reaction. Polydopamine-modified zinc dioxide nanoflowers, as ECL acceptors, inhibited Ru-ZnMOF ECL signaling. The linear range of NSE was 10 fg mL-1 to 100 ng mL-1 with a detection limit of 3.3 fg mL-1 (S/N = 3), which is suitably low for determining NSE in real samples.

Signal "On-Amplified-Off" Strategy Based on Hafnium Dioxide Nanomaterials as Electrochemiluminescence Emitters for Progesterone Detection

When consumed, excess progesterone (P4)─found in food and the environment─can lead to severe illnesses in humans. Therefore, quantitative analysis of P4 is critical for identifying its hazardous levels. In this study, a novel signal "on-amplified-off" P4 detection mode was proposed, which was based on the utilization of hafnium oxide (HfO2) as a unique electrochemiluminescence (ECL) emitter, produced by calcining UiO-66(Hf). This is the first time that HfO2 has been used as an ECL emitter. HfO2 displayed excellent conductivity and a high specific surface area, allowing it to connect with numerous aptamers and produce a "signal-on" effect. Ni-doped ZnO (Ni-ZnO) acted as a coreaction accelerator, enhancing the ECL strength of HfO2 by generating more tripropylamine radicals. cDNA was labeled with Ni-ZnO, and Ni-ZnO was linked to the aptamer via base complementary pairing, affording "signal-amplified". The presence of the target molecule P4 instigated a specific binding process with the aptamer, triggering the shedding of cDNA-Ni-ZnO and resulting in "signal-off". This novel "on-amplified-off" strategy effectively improved the sensitivity and specificity of P4 analysis, introducing a practical method for detecting biomolecules beyond the scope of this study, which holds immense potential for future applications.

A polyaniline functionalized NiFeP nanosheet array-based electrochemical immunosensor using Au/Cu2O nanocubes as a signal amplifier for the detection of SARS-CoV-2 nucleocapsid protein

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which emerged as a novel pathogen in 2019. The virus is responsible for a severe acute respiratory syndrome outbreak, affecting the respiratory system of infected individuals. COVID-19 is a super amplifier of basic diseases, and the disease with basic diseases is often more serious. Controlling the spread of the COVID-19 pandemic relies heavily on the timely and accurate detection of the virus. To resolve the problem, a polyaniline functionalized NiFeP nanosheet array-based electrochemical immunosensor using Au/Cu₂O nanocubes as a signal amplifier is fabricated for the detection of SARS-CoV-2 nucleocapsid protein (SARS-CoV-2 NP). Polyaniline (PANI) functionalized NiFeP nanosheet arrays are synthesized as an ideal sensing platform for the first time. PANI is coated on the surface of NiFeP by electropolymerization to enhance biocompatibility, beneficial for the efficient loading of the capture antibody (Ab₁). Significantly, Au/Cu₂O nanocubes possess excellent peroxidase-like activity and exhibit outstanding catalytic activity for the reduction of H₂O₂. Therefore, Au/Cu₂O nanocubes combine with a labeled antibody (Ab₂) through the Au-N bond to form labeled probes, which can effectively amplify current signals. Under optimal conditions, the immunosensor for the detection of SARS-CoV-2 NP shows a wide linear range of 10 fg mL^-1-20 ng mL^-1 and a low detection limit of 1.12 fg mL^-1 (S/N = 3). It also exhibits desirable selectivity, repeatability, and stability. Meanwhile, the excellent analytical performance in human serum samples confirms the practicality of the PANI functionalized NiFeP nanosheet array-based immunosensor. The electrochemical immunosensor based on the Au/Cu₂O nanocubes as a signal amplifier demonstrates great potential for application in the personalized point-of-care (POC) clinical diagnosis.