Versatile NiCo2O4 nanosheets hybrids-based label-free immunosensor for thyroglobulin using photothermal amplification

A homogeneous electrochemiluminescence immunoassay platform based on carbon quantum dots and magnetic beads enrichment for detection of thyroglobulin in serum

Considering the high probability of recurrence or metastasis after thyroidectomy, it is meaningful to develop a rapid, sensitive and specific method for monitoring thyrophyma-related biomarkers. In this study, a homogeneous electrochemiluminescence immunoassay (HO-ECLIA) coupled with magnetic beads (MBs)-based enrichment tactic was established for the determination of thyrophyma-related thyroglobulin (Tg). Importantly, owing to the abundant surface groups and good biocompatibility of carbon quantum dots (CQDs), the incorporation of CQDs onto the Tg antigen surface was achieved, resulting in the formation of Tg-encapsulated CQDs (CQDs-Tg), which served not only as an ECL probe but as a biorecognition element. Under optimal experimental conditions, the proposed platform demonstrated a wide linear range from 0.01 to 100 ng·mL-1 with a detection limit of 6.9 pg·mL-1 (S/N = 3), and performed well in real serum sample analysis against interference. Collectively, the proposed platform exhibited the rapid response, satisfactory sensitivity and specificity toward Tg in complex serum milieu, and held a considerable potential for clinical prognosis monitoring of thyrophyma.

Facile and portable multimodal sensing platform driven by photothermal-controlled release system for biomarker detection

Portable, maneuverable and reliable versatile-integrated analytical devices are urgently demanded but still extremely challenging to meet the requirements of point-of-care testing in resource-limited areas. Herein, a multifunctional sensing platform with excellent photothermal performance was implanted into the miniature zone of a paper-based electrochemiluminescent (ECL) biosensor for accurate detection of interleukin-6, which could flexibly interconnect the visualized distance and temperature readout with ultrasensitive ECL response. Concretely, the multipurpose MBene and TaSe₂ composites (MBene@TaSe₂) prepared via self-assembly approach as target-associated photothermal element was introduced in the paper-based analytical device (PAD) and served as multi-signals trigger. Under the laser irradiation, MBene@TaSe₂ probe not only generated heat for rapid temperature output, but also triggered the phase transition behavior of thermoresponsive poly (N-isopropylacrylamide) (pNIPAM) hydrogel to release loaded malachite green (MG) dye for distance-based visual readout. Simultaneously, the released MG was also utilized as effective quencher to decrease the ECL signal of luminol. Benefitting from this dexterous architecture, the speedy preliminary screening and precise quantitative analysis could be subsequently obtained in single-drop sample through one-step sandwich immunoreaction, which avoids additional separation operations and greatly simplifies the analysis procedure. Undeniably, this work provides ingenious insights for advancing the development of convenient and fast multifunction-integrated PAD in family surveillance and intelligent diagnosis.

Photoelectrochemical immunoassay for thyroglobulin on nanogold-functionalized BiVO4 photoanode coupling with enzymatic biocatalytic precipitation

Methods derived from photoelectrochemical (PEC) have been constructed for immunoassays, but most involve the split-type immunoreaction modes, and thus easily cause unpredictable intermediate precision. Herein, we innovatively designed an integrated PEC immunosensing platform for the quantitative monitoring of thyroglobulin (TG) on the gold nanoparticles (AuNPs)-functionalized BiVO₄ photoanode coupling with enzymatic biocatalytic precipitation (EBCP). This sensing system could simultaneously implement the immunoreaction and photocurrent measurement. Anti-TG capture antibodies were modified onto AuNPs-decorated BiVO₄ photoelectrode. A sandwich-type immunoreaction was carried out in the presence of target TG using horseradish peroxidase (HRP)-conjugated anti-TG detection antibody. The carried HRP molecules catalyzed 4-chloro-1-naphthol (4-CN) to generate an insoluble benzo-4-chlorohexadienone product on the photoanode in the presence of peroxide hydrogen, thereby decreasing the photocurrent. Under optimal conditions, the PEC immunosensors gave good photocurrent responses toward target TG within the dynamic range of 0.01-10 ng mL^-1 at a detection limit of 7.6 pg mL^-1. Good repeatability and precision, high specificity and acceptable storage stability were acquired during the measurement. No significant differences were encountered for screening 15 human serum specimens between the developed PEC immunoassay and commercially available enzyme-linked immunosorbent assay (ELISA) method for the detection of target TG. Significantly, PEC immunosensing system offers promise for simple and cost-effective analysis of disease-related biomarkers.

Nanotechnology-based approaches for effective detection of tumor markers: A comprehensive state-of-the-art review

As well-appreciated biomarkers, tumor markers have been spotlighted as reliable tools for predicting the behavior of different tumors and helping clinicians ascertain the type of molecular mechanism of tumorigenesis. The sensitivity and specificity of these markers have made them an object of even broader interest for sensitive detection and staging of various cancers. Enzyme-linked immunosorbent assay (ELISA), fluorescence-based, mass-based, and electrochemical-based detections are current techniques for sensing tumor markers. Although some of these techniques provide good selectivity, certain obstacles, including a low sample concentration or difficulty carrying out the measurement, limit their application. With the advent of nanotechnology, many studies have been carried out to synthesize and employ nanomaterials (NMs) in sensing techniques to determine these tumor markers at low concentrations. The fabrication, sensitivity, design, and multiplexing of sensing techniques have been uplifted due to the attractive features of NMs. Various NMs, such as magnetic and metal nanoparticles, up-conversion NPs, carbon nanotubes (CNTs), carbon-based NMs, quantum dots (QDs), and graphene-based nanosensors, hyperbranched polymers, optical nanosensors, piezoelectric biosensors, paper-based biosensors, microfluidic-based lab-on-chip sensors, and hybrid NMs have proven effective in detecting tumor markers with great sensitivity and selectivity. This review summarizes various categories of NMs for detecting these valuable markers, such as prostate-specific antigen (PSA), human carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), human epidermal growth factor receptor-2 (HER2), cancer antigen 125 (CA125), cancer antigen 15-3 (CA15-3, MUC1), and cancer antigen 19-9 (CA19-9), and highlights recent nanotechnology-based advancements in detection of these prognostic biomarkers.

Recent progress in water-splitting electrocatalysis mediated by 2D noble metal materials

Two-dimensional (2D) nanostructures have enabled noble-metal-based nanomaterials to be promising electrocatalysts toward overall water splitting due to their inherent structural advantages, including a high specific surface active area, numerous low-coordinated atoms, and a high density of defects and edges. Moreover, it is also disclosed that the electronic effect and strain effect within 2D nanostructures also benefit the further promotion of the electrocatalytic performance. In this review, we have focused on the recent progress in the fabrication of advanced electrocatalysts based on 2D noble-metal-based nanomaterials toward water splitting electrocatalysis. First, fundamental descriptions about water-splitting mechanisms, some promising engineering strategies, and major challenges in electrochemical water splitting are given. Then, the structural merits of 2D nanostructures for water splitting electrocatalysis are also highlighted, including abundant surface active sites, lattice distortion, abundant surface defects, electronic effects, and strain effects. Additionally, some representative water-splitting electrocatalysts have been discussed in detail to highlight the superiorities of 2D noble-metal-based nanomaterials for electrochemical water splitting. Finally, the underlying challenges and future opportunities for the fabrication of more advanced electrocatalysts for water splitting are also highlighted. We hope that this review article provides guidance for the fabrication of more efficient electrocatalysts for boosting industrial hydrogen production via water splitting.

Highly sensitive electrochemical immunosensor using a protein-polyvinylidene fluoride nanocomposite for human thyroglobulin

The highly sensitive detection of serum thyroglobulin (Tg) is essential in the post-treatment follow-up of patients with differentiated thyroid cancer undergoing total or partial thyroidectomy and radioactive iodine ablation and requires sensitive, accurate and stable methods. This work proposes an electrochemical immunosensor for the detection of serum Tg antigen, making use of innovative nanocomposites including polyvinylidene fluoride (PVDF) microparticles coated with streptavidin (MP) and gold nanoparticles (AuNPs). The functionalized polymer matrices were characterized by UV-Vis, FTIR, XPS, SEM, dynamic light scattering, and free surface energy. Immobilization of biotin-labeled anti-thyroglobulin monoclonal antibodies was achieved by binding these to the polymer nanocomposite via streptavidin proteins. The analytical response was measured in quintuplicate and had a linear profile from 2.0 to 10.0 ng/mL Tg, with r² of 0.985. The limits of detection and quantification were excellent, equal to 0.015 and 0.047 ng/mL, respectively. In addition, the recovery factor was equal to 95.4% (1.0 ng/mL Tg). Overall, the innovative polymer-based nanocomposite used herein enabled the production of an electrochemical-based immunosensor with excellent sensitivity, selectivity, and reproducibility. It evidenced the remarkable potential of determining low levels of Tg in in vitro assays, thereby suggesting that it may be considered for the analyzes of serum patients.

Simple and rapid nicotine analysis using a disposable silica nanochannel-assisted electrochemiluminescence sensor

Nicotine analysis is essential to medicine, toxicology and the tobacco industry. However, no simple, portable and disposable method was developed to meet their demands. Here, we report a simple, rapid and disposable silica nanochannel (SAN)-based electrochemiluminescence (ECL) sensor for nicotine analysis by simply assembling a SAN electrode with a paper cover. The sensing principle of the disposable sensor is based on the size exclusion effect and charge selectivity, which obviously prolong the sensor service time. We find that the sensor exhibits good specificity to nicotine, and most of the complex matrices are unlikely to impact the detection. The performance of the disposable sensor in cigarettes, e-cigarettes, nicotine gums, and lozenges is fully validated, showing satisfactory linearity, sensitivity (a limit of detection of 27.82 nM), and accuracy (a recovery between 96.00% and 106.51%). The disposable sensor can be potentially applied for on-site nicotine analysis.