Recent advances in microfluidic paper-based electrochemiluminescence analytical devices for point-of-care testing applications

Progress in miRNA Detection Using Graphene Material-Based Biosensors

MicroRNAs (miRNAs) are short, endogenous, noncoding RNAs that play critical roles in physiologic and pathologic processes and are vital biomarkers for several disease diagnostics and therapeutics. Therefore, rapid, low-cost, sensitive, and selective detection of miRNAs is of paramount importance and has aroused increasing attention in the field of medical research. Among the various reported miRNA sensors, devices based on graphene and its derivatives, which form functional supramolecular nanoassemblies of π-conjugated molecules, have been revealed to have great potential due to their extraordinary electrical, chemical, optical, mechanical, and structural properties. This Review critically and comprehensively summarizes the recent progress in miRNA detection based on graphene and its derivative materials, with an emphasis on i) the underlying working principles of these types of sensors, and the unique roles and advantages of graphene materials; ii) state-of-the-art protocols recently developed for high-performance miRNA sensing, including representative examples; and iii) perspectives and current challenges for graphene sensors. This Review intends to provide readers with a deep understanding of the design and future of miRNA detection devices.

Recent Advances in Electrochemiluminescence Sensors for Pathogenic Bacteria Detection

Pathogenic bacterial contamination greatly threats human health and safety. Rapidly biosensing pathogens in the early stage of infection would be helpful to choose the correct drug treatment, prevent transmission of pathogens, as well as decrease mortality and economic losses. Traditional techniques, such as polymerase chain reaction and enzyme-linked immunosorbent assay, are accurate and effective, but are greatly limited because they are complex and time-consuming. Electrochemiluminescence (ECL) biosensors combine the advantages of both electrochemical and photoluminescence analysis and are suitable for high sensitivity and simple pathogenic bacteria detection. In this review, we summarize recent advances in ECL sensors for pathogenic bacteria detection and highlight the development of paper-based ECL platforms in point of care diagnosis of pathogens.

Current Trends in the Biosensors for Biological Warfare Agents Assay

Biosensors are analytical devices combining a physical sensor with a part of biological origin providing sensitivity and selectivity toward analyte. Biological warfare agents are infectious microorganisms or toxins with the capability to harm or kill humans. They can be produced and spread by a military or misused by a terrorist group. For example, Bacillus anthracis, Francisella tularensis, Brucella sp., Yersinia pestis, staphylococcal enterotoxin B, botulinum toxin and orthopoxviruses are typical biological warfare agents. Biosensors for biological warfare agents serve as simple but reliable analytical tools for the both field and laboratory assay. There are examples of commercially available biosensors, but research and development of new types continue and their application in praxis can be expected in the future. This review summarizes the facts and role of biosensors in the biological warfare agents' assay, and shows current commercially available devices and trends in research of the news. Survey of actual literature is provided.

Electrochemiluminescence "turn-off" detection of curcumin via energy transfer using luminol-doped silica nanoparticles

A method is presented for electrochemiluminescent (ECL) detection of the food additive curcumin via an energy transfer strategy and by using luminol-doped silica nanoparticles (luminol-NPs). The ECL emission of the luminol-NPs (peaking at 425 nm) is reduced in the presence of curcumin due to spectral overlap. The assay can be performed within 1 min, response is linear in the 0.1 to 100 µM curcumin concentration range, and the limit of detection is 32 nM. The method is selective over many ions, adenosine triphosphate, ascorbic acid, cysteine and folic acid. It was successfully applied to the determination of curcumin in spiked human serum and urine. The average recoveries range from 99.0 to 102.6%. Graphical abstract Electrochemiluminescence (ECL) "turn-off" detection of curcumin at levels as low as 32 nM via energy transfer using luminol-doped silica nanoparticles. No hydrogen peroxide (H₂O₂) is used in ECL detection which makes the luminol-NPs ECL system more stable than the conventional luminol-H₂O₂ ECL system.

Enhanced electrochemiluminescent brightness and stability of porphyrins by supramolecular pinning and pinching for sensitive zinc detection

Ultrasensitive electrochemiluminescence (ECL) detection can benefit substantially from the rational configuration of emitter-enhancer stereochemistry. Here, using zinc(II) meso-5,10,15,20-tetra(4-sulfonatophenyl)porphyrin (ZnTSPP) as a model, we demonstrate that both the ECL intensity and the photostability of this emitter were significantly improved when it was trapped in pyridyl-bridged β-cyclodextrin dimer (Py(CD)₂); a synthetic enhancer that is ECL inactive. Through NMR characterization, we confirmed that ZnTSPP formed a clam-like inclusion complex involving pinning and pinching forces from the biocompatible container Py(CD)₂. Up to a threefold increase in the ECL brightness of ZnTSPP was witnessed when it was encapsulated in β-CD. Absorption and emission spectroscopic data revealed that both the extended excitation lifetime and the restricted mobility of the guest contributed to the observed improvement in signal transduction within the host molecule. This bioinspired entrapment also led to a marked boost in ECL stability. With the aid of the newly identified coreactant H₂O₂, the hollow TSPP@Py(CD)₂ system was employed to create a Zn²⁺-selective probe that was capable of sensitive and accurate zinc detection. The observed increase in ECL conversion and enhanced photophysical properties of this compact supramolecular assembly render it a novel template for enhancing ECL in analytical applications. Graphical abstract ᅟ.

Advanced impedimetric biosensor configuration and assay protocol for glycoprofiling of a prostate oncomarker using Au nanoshells with a magnetic core

In this paper several advances were implemented for glycoprofiling of prostate specific antigen (PSA), what can be applied for better prostate cancer (PCa) diagnostics in the future: 1) application of Au nanoshells with a magnetic core (MP@silica@Au); 2) use of surface plasmons of Au nanoshells with a magnetic core for spontaneous immobilization of zwitterionic molecules via diazonium salt grafting; 3) a double anti-fouling strategy with integration of zwitterionic molecules on Au surface and on MP@silica@Au particles was implemented to resist non-specific protein binding; 4) application of anti-PSA antibody modified Au nanoshells with a magnetic core for enrichment of PSA from a complex matrix of a human serum; 5) direct incubation of anti-PSA modified MP@silica@Au with affinity bound PSA to the lectin modified electrode surface. The electrochemical impedance spectroscopy (EIS) signal was enhanced 43 times integrating Au nanoshells with a magnetic core compared to the biosensor without them. This proof-of-concept study shows that the biosensor could detect PSA down to 1.2 fM and at the same time to glycoprofile such low PSA concentration using a lectin patterned biosensor device. The biosensor offers a recovery index of 108%, when serum sample was spiked with a physiological concentration of PSA (3.5 ng mL^-1).

Ultrasensitive detection of transcription factors with a highly-efficient diaminoterephthalate fluorophore via an electrogenerated chemiluminescence strategy

Herein, we apply electrogenerated chemiluminescence (ECL) based method employing diaminoterephthalate analogue as ECL emitter and hairpin DNA as amplification strategy, for sensitive assay of transcription factors.