Electrogenerated chemiluminescence biosensing for the detection of prostate PC-3 cancer cells incorporating antibody as capture probe and ruthenium complex-labelled wheat germ agglutinin as signal probe

A novel carboxyl polymer-modified upconversion luminescent nanoprobe for detection of prostate-specific antigen in the clinical gray zonebase by flow immunoassay strip

Prostate specific antigen (PSA) is a widely-used biomarker for the diagnosis, screening, and prognosis of prostate cancer (PCa). It is critical to develop a rapid and convenient method to accurately detect PSA levels, especially when the PSA levels are in the clinical gray area of 4-10 ng/mL. We developed a novel upconversion nanoparticle (UCNP)-based fluorescence lateral flow test strip for qualitatively and quantitatively detecting PSA. The carboxyl group-modified UCNPs (UCNP-COOH) were labeled with anti-PSA antibodies via 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as labeling probes to recognize PSA. The fluorescence intensity of the UCNP-probe was then measured with a laser fluorescence scanner. A total of 1397 serum and 20 fingertip blood samples were collected to validate the UCNP strip. A reliable correlation between the area ratio (TC), reflecting the fluorescence intensity of the test/control line, and the PSA concentration was observed (r = 0.9986). The dose-dependent luminescence enhancement showed good linearity in the PSA concentration range from 0.1 to 100.0 ng/mL with a detection limit of 0.1 ng/mL. Our UCNP POCT strip demonstrated excellent accuracy, anti-interference and stability in the gray zone (4-10 ng/mL) of PSA clinical application and outperformed other PSA test strips. The UCNP strip showed good consistency with the Roche chemiluminescence assay in 1397 serum samples. It also showed good performance for PSA detection using fingertip blood samples. This novel UCNP-based test strip could be a sensitive and reliable POCT assay to detect PSA, facilitating the diagnosis and surveillance of PCa.

Recent advances and challenges in developing electrochemiluminescence biosensors for health analysis

This Feature Article simply introduces principles and mechanisms of electrochemiluminescence (ECL) biosensors for the determination of biomarkers and highlights recent advances of ECL biosensors on key aspects including new ECL reagents and materials, new biological recognition elements, and emerging construction biointerfacial strategies with illustrative examples and a critical eye on pitfalls and discusses challenges and perspectives of ECL biosensors for health analysis.

Systematic review on lectin-based electrochemical biosensors for clinically relevant carbohydrates and glycoconjugates

Carbohydrates and glycoconjugates are involved in numerous natural and pathological metabolic processes, and the precise elucidation of their biochemical functions has been supported by smart technologies assembled with lectins, i.e., ubiquitous proteins of nonimmune origin with carbohydrate-specific domains. When lectins are anchored on suitable electrochemical transducers, sensitive and innovative bioanalytical tools (lectin-based biosensors) are produced, with the ability to screen target sugars at molecular levels. In addition to the remarkable electroanalytical sensitivity, these devices associate specificity, precision, stability, besides the possibility of miniaturization and portability, which are special features required for real-time and point-of-care measurements. The mentioned attributes can be improved by combining lectins with biocompatible 0-3D semiconductors derived from carbon, metal nanoparticles, polymers and their nanocomposites, or employing labeled biomolecules. This systematic review aims to substantiate and update information on the progress made with lectin-based biosensors designed for electroanalysis of clinically relevant carbohydrates and glycoconjugates (glycoproteins, pathogens and cancer biomarkers), highlighting their main detection principles and performance in highly complex biological milieus. Moreover, particular emphasis is given to the main advantages and limitations of the reported devices, as well as the new trends for the current demands. We believe that this review will support and encourage more cutting-edge research involving lectin-based electrochemical biosensors.

Graphitic C3N4 nanosheet and hemin/G-quadruplex DNAzyme-based label-free chemiluminescence aptasensing for biomarkers

Here we first reported that graphitic carbon nitride nanosheet (g-C₃N₄ NS) could effectively quench the chemiluminescence (CL) of luminol-hydrogen peroxide (H₂O₂) system. According to the new discovery, a label-free and homogeneous CL aptasensing platform was designed for sensitive detecting of biomarkers. In the absence of target, DNA probe containing hemin/G-quadruplex DNAzyme structure was adsorbed on the surface of g-C₃N₄ NS, causing the CL quenching of luminol through an electron transfer process. However, in the presence of the target, a DNA-DNA duplex was formed due to DNA hybridization reaction and target recognition effect, which could not be adsorbed onto the g-C₃N₄ NS surface because of its weak affinity. Thus, the electron transfer was blocked and the CL emission of luminol could be enhanced. The proposed CL aptasensor could detect carcinoembryonic antigen (CEA) with a detection limit of 63.0 pg/mL and it can also be used as a general detecting strategy for adenosinetriphosphate (ATP) detection. This aptasensing platform exhibited high sensitivity toward biomarkers and the probe need not be labeled, showing great promise for disease diagnosis.

Spatial-Resolved Photoelectrochemical Biosensing Array Based on a CdS@g-C3N4 Heterojunction: A Universal Immunosensing Platform for Accurate Detection

The detection of biomarkers with high sensitivity and accuracy in real biosamples remains challenging. Herein, a universal spatial-resolved photoelectrochemical (PEC) ratiometry for biodetection of prostate-specific antigen (PSA) as model biomarker was designed for the first time based on a dual-electrode array modified by CdS@g-C₃N₄ heterojunction coupled with CuS quantum dots (QDs) as signal amplification tags. Specifically, a new kind of photoactive material, the CdS@g-C₃N₄ p-n heterojunction with high photoelectric conversion efficiency and good chemical stability, was synthesized and immobilized on two spatial-resolved electrodes (WE1 and WE2). After immobilizing gold nanoparticles and capturing PSA antibodies on the electrodes, WE1 incubated with various concentrations of PSA was taken as a working electrode, whereas WE2 with a fixed concentration of PSA was used as an internal reference electrode. Next, signal antibodies of PSA-labeled CuS QDs as PEC signal quenchers were immobilized on the electrodes to form a sandwich-type immunocomplex. With the aid of a multiplexed disjunctor, the PEC responses of the dual electrodes were recorded, and the PSA was quantified via the ratio values of photocurrent intensities from WE1 and WE2. Combining the fine PEC performance of the CdS@g-C₃N₄ heterojunction with the superior quenching effect of CuS QDs in the spatial-resolved platform, the ratiometric system exhibits a linear range from 1.0 × 10^-11 to 5.0 × 10^-8 g mL^-1 with a limit of detection of 4.0 pg mL^-1. The results demonstrated herein may provide a new pattern for biomarker detection with high accuracy and good specificity as well as satisfactory applicability in real biosamples.

Nanotechnology in Glycomics: Applications in Diagnostics, Therapy, Imaging, and Separation Processes

This review comprehensively covers the most recent achievements (from 2013) in the successful integration of nanomaterials in the field of glycomics. The first part of the paper addresses the beneficial properties of nanomaterials for the construction of biosensors, bioanalytical devices, and protocols for the detection of various analytes, including viruses and whole cells, together with their key characteristics. The second part of the review focuses on the application of nanomaterials integrated with glycans for various biomedical applications, that is, vaccines against viral and bacterial infections and cancer cells, as therapeutic agents, for in vivo imaging and nuclear magnetic resonance imaging, and for selective drug delivery. The final part of the review describes various ways in which glycan enrichment can be effectively done using nanomaterials, molecularly imprinted polymers with polymer thickness controlled at the nanoscale, with a subsequent analysis of glycans by mass spectrometry. A short section describing an active glycoprofiling by microengines (microrockets) is covered as well.

Biosensing breast cancer cells based on a three-dimensional TIO2 nanomembrane transducer

The early diagnosis of breast cancer is crucial for the successful treatment and recovery phases of the patients suffering from the disease. Although mammography is considered the gold standard for diagnosis, it fails to detect some cancers in high-density breasts. In this work, we propose for the first time a tridimensional biosensor platform, to be used on an electrochemical point-of-care device. The bioconjugated platform is constructed on a series of covalent linkages between lectin molecules and a cysteine layer immobilized over gold-coated TiO₂ butterfly-like tridimensional nanomembranes. Through the use of vegetal lectins, we managed to take advantage of the markedly atypical glycomic profile of the cancerous mammalian cell membrane and successfully made a distinction between highly invasive (T47D) and less invasive (MCF7) cancer cell lines. The selectivity of the biosensor was tested by using normal human skin-fibroblast. The proposed cytosensor demonstrated limits of detection as low as 10 cells mL^-1 for every cell line and a linear range from 10 to 1.0×10⁶ cells mL^-1. Considering that electrochemical impedance values can be correlated with the number of breast cancer cells present in the sample, we suggest that the proposed platform could be useful in facilitating the diagnosis of cancer.

Development of a sandwiched microarray platform for studying the interactions of antibiotics with Staphylococcus aureus

It still confronts an outstanding challenge to screen efficient antibacterial drugs from millions of potential antibiotic candidates. In this regard, a sandwiched microarray platform has been developed to culture live bacteria and carry out high-throughput screening antibacterial drugs. The optimized lectin-hydrogel microarray can be used as an efficient bacterial capturing and culturing platform, which is beneficial to identify spots and collect data. At the same time, a matching drug-laden polyacrylamide microarray with Luria-Bertani (LB) culture medium can be generated automatically and accurately by using a standard non-contacting procedure. A large number of microscale culture chambers (more than 100 individual samples) between two microarrays can be formed by linking two aligned hydrogel spots using LB culture medium, where live bacteria can be co-cultured with drug candidates. Using Staphylococcus aureus (S. aureus) and four well-known antibiotics (amoxicillin, vancomycin, streptomycin and chloramphenicol) as model system, the MIC (minimum inhibitory concentration) values of the antibiotics can be determined by the drug induced change of bacterial growth, and the results demonstrate that the MIC values of amoxicillin, vancomycin and streptomycin are 1.7 μg mL(-1), 3.3 μg mL(-1) and 10.3 μg mL(-1), respectively.