An adjustable amyloid-β oligomers aptasensor based on the synergistic effect of self-enhanced metal-organic gel luminophore and triple-helix DNA system

Bright luminescent Zn2GeO4:Mn NP/MXene hydrogel-based ECL biosensor for glioblastoma diagnosis

In this work, miRNA-10b in the glioblastoma (GBM) tumor tissues has been detected by a novel electrochemiluminescence (ECL) biosensor. Firstly, a new kind of bright luminescent Zn2GeO4:Mn NPs were prepared as ECL nanoprobe, which possessed high fluorescence quantum yield and ECL quantum efficiency. Secondly, Ti3C2 MXene hydrogel (MXG) have been developed as the sensing interface. The MXG retained the inherent biocompatibility and mechanical features of hydrogel. Furthermore, the uniform distribution of metallic Ti3C2 MXene in the hydrogel microstructure provided the good conductivity and multiple binding sites for biomolecules. MXene also can promote the separation of the electrons and holes to accelerate the electron-transfer rate and improve ECL efficiency. Due to these synergistic effects, the screen printed electrode was successfully modified with MXG as sensing platform to enhance the ECL intensity of Zn2GeO4:Mn NP, which greatly improved the detection efficiency and facilitated the high-throughput analysis. Finally, the toehold mediated strand displacement (TMSD) strategy was employed with then biosensor to detect miRNA-10b with the range of 10 fM to 1 nM. The limit of detection was 5 fM. This ECL biosensor has been used to analyze miRNA-10b expression in GBM tumor tissues, which possessed the great potential value for clinical diagnosis.

An Encyclopedic Compendium on Chemosensing Supramolecular Metal-Organic Gels

Chemosensing, an interdisciplinary scientific domain, plays a pivotal role ranging from environmental monitoring to healthcare diagnostics and (inter)national security. Metal-organic gels (MOGs) are recognized for their stability, selectivity, and responsiveness, making them valuable for chemosensing applications. Researchers have explored the development of MOGs based on different metal ions and ligands, allowing for tailored properties and sensitivities, and have even demonstrated their applications as portable sensors such as paper-based test strips for practical use. Herein, several studies related to MOGs development and their applications in the chemosensing field via UV-visible or luminance along with electrochemical approach are presented. These papers explored MOGs as versatile materials with their use in sensing bio or environmental analytes. This review provides a foundational understanding of key concepts, methodologies, and recent advancements in this field, fostering the scientific community.

Ultrasensitive Aptasensing Platform for the Detection of β-Amyloid-42 Peptide Based on MOF Containing Bimetallic Porphyrin Graphene Oxide and Gold Nanoparticles

The prompt detection of diseases hinges on the accessibility and the capability to identify relevant biomarkers. The integration of aptamers and the incorporation of nanomaterials into signal transducers have not only expedited but also enhanced the development of nanoaptasensors, enabling heightened sensitivity and selectivity. Here, the bimetallic nickel-cobalt-porphyrin metal-organic framework ((Ni + Cu)TPyP MOF) is regarded as an electron mediator, immobilization platform for an Alzheimer aptamer and to increase the electrochemical signal for the detection of the main biomarker of Alzheimer's disease (AD), amyloid β (Aβ-42). Furthermore, the ((Ni + Cu)TPyP MOF) was combined with reduced graphene oxide (rGO) and gold nanoparticles (AuNPs), on a gold electrode (GE) to provide an efficient interface for immobilizing aptamer strands. Concurrently, the incorporation of rGO and AuNPs imparts enhanced electrical conductivity and efficacious catalytic activity, establishing them as adept electrochemical indicators. Owing to the superior excellent electrical conductivity of rGO and AuNPs, coupled with the presence of ample mesoporous channels and numerous Ni and Cu metal sites within (Ni + Cu)TPyP MOF, this nanostructure with abundant functional groups is proficient in immobilizing a substantial quantity of aptamer. These interactions are achieved through robust π-π stacking and electrostatic interactions, alongside the high affinity between the thiol group of the aptamer and AuNPs concurrently. The as-prepared ternary (Au@(Ni + Cu)TPyP MOF/rGO) nanostructure electrode exhibited an enhancement in its electrochemically active surface area of about 7 times, compared with the bare electrode and the Aβ-42 redox process is highly accelerated, so the peak currents are significantly higher than those obtained with bare GE substrate. Under the optimized conditions, the designed aptasensor had the quantitative detection of Aβ-42 with a low detection limit of 48.6 fg mL-1 within the linear range of 0.05 pg mL-1 to 5 ng mL-1 by differential pulse voltammetry (DPV), accompanied by precise reproducibility, satisfactory stability (95.6% of the initial activity after 10 days), and minimal impact of interfering agents. Recorded results in human blood plasma demonstrated the high efficacy of porphyrin MOF system sensing even in the clinical matrix. The great performance of this aptasensor indicates that our new design of Au@(Ni + Cu)TPyP MOF/rGO nanostructure provides more opportunities for the detection of chemical signals in early diagnosis of Alzheimer's disease.

Novel immunosensor based on electrochemiluminescence inner filter effect and static quenching between fibrillary Ag-MOGs and SiO2@PANI@AuNPs for enabling the sensitive detection of neuron-specific enolase

Metal-organic gels (MOGs) are unique supramolecular gels that are convenient to synthesize. In this work, a cathodic electrochemiluminescence (ECL) system based on Ag-MOGs as a luminophore and K2S2O8 as a co-reactor was developed. The ECL spectrum of the Ag-MOGs overlapped significantly with the strong UV-Vis spectrum of the SiO2@PANI@AuNPs, which effectively quenched the ECL luminescence of the Ag-MOGs. Relying on the inner filter effect between Ag-MOGs and SiO2@PANI@AuNPs, a novel ECL-IFE immunosensor was developed for the detection of neuron-specific enolase (NSE). Under optimal conditions, the ECL signal of the immunosensor displayed excellent linearity over the NSE concentration range of 10 fg/mL-100 ng/mL. The limit of detection (LOD) was 2.6 fg/mL (S/N = 3) with a correlation coefficient R2 of 0.9975. The ECL immunosensor also exhibited excellent stability and reproducibility for the detection of NSE. The results reported provide a feasible concept for the development analytical methods for the detection of other clinically relevant biomarkers.

PdPtB Electrochemiluminescence Nanoenhancer and SiC@Au-PEDOT Nanowires-Based Detection of β-Amyloid Oligomers in Alzheimer's Disease

β-Amyloid oligomers (AβOs) are promising biomarkers for the diagnosis of Alzheimer's disease (AD). The present research introduces a novel electrochemiluminescence (ECL) immunosensor based on PdPtB nanoenhancer and SiC@Au-PEDOT nanowires (NWs) for the specific and ultrasensitive detection of AβOs. The PdPtB nanoenhancer exhibited excellent oxidase-like catalytic activity with in situ generation of reactive oxygen species (ROS) to enhance luminol ECL in neutral media. In addition, SiC@Au-PEDOT NWs were utilized as a biocompatible and conductive substrate for the modification of the glassy carbon electrode (GCE). With this design, the ECL immunosensor showed outstanding AβOs analytical performance without exogenous coreactant. The ECL immunosensor demonstrated a favorable linear range of 20 pM to 20 nM and a detection limit of 10 pM under optimized conditions with potential straightforward clinical application. In general, the developed ECL immunosensor provides a promising strategy for the early diagnosis of AD.

Design of an electrochemical aptasensor in the presence of an array of gold nanostructure and a GO-MWCNTs nanocomposite: application in diagnosis of Alzheimer's disease

Alzheimer's disease (AD) is considered one of the main progressive chronic diseases in elderly individuals. Early diagnosis using related biomarkers, specifically beta-amyloid peptide (Aβ), allows finding expected treatment routes. Here, we developed an electrochemical aptasensing platform for AD by employing a glassy carbon electrode (GCE) modified with a layer of jagged gold (JG) nanostructure (diameter: 60-185 nm) and graphene oxide-carboxylic acid functionalized multiwalled carbon nanotubes (GO-c-MWCNTs) nanocomposite. These surface modifications acted as the signal amplifier and provided an optimum nano-interface substrate for immobilizing aptamer strands. The measurements of Aβ were performed via differential pulse voltammetry (DPV), and the aptasensor detected the analyte in a linear range from 0.1 pg mL-1 to 1 ng mL-1, with an estimated limit of detection (LOD) of about 0.088 pg mL-1 (S/N = 3). The aptasensor showed sufficient stability (11 days), reversibility (three times), and reproducibility (five times re-fabrication with relative standard deviation (RSD): 1.27). The potential interfering agents showed negligible impact on the sensing performance. Finally, the application of the aptasensor was evaluated in the presence of 10 serum samples, and the recovery values were from 93 to 110.1%.

Recent advances in electrochemical nanomaterial-based aptasensors for the detection of cancer biomarkers

New technologies have provided suitable tools for rapid diagnosis of cancer which can reduce treatment costs and even increase patients' survival rates. Recently, the development of electrochemical aptamer-based nanobiosensors has raised great hopes for early, sensitive, selective, and low-cost cancer diagnosis. Here, we reviewed the flagged recent research (2021-2023) developed as a series of biosensors equipped with nanomaterials and aptamer sequences (nanoaptasensors) to diagnose/prognosis of various types of cancers. Equipping these aptasensors with nanomaterials and using advanced biomolecular technologies have provided specified biosensing interfaces for more optimal and reliable detection of cancer biomarkers. The primary intention of this review was to present and categorize the latest innovations used in the design of these diagnostic tools, including the hottest surface modifications and assembly of sensing bioplatforms considering diagnostic mechanisms. The main classification is based on applying various nanomaterials and sub-classifications considered based on the type of analyte and other vital features. This review may help design subsequent electrochemical aptasensors. Likewise, the up-to-date status, remaining limitations, and possible paths for translating aptasensors to clinical cancer assay tools can be clarified.