Electrochemiluminescence of Semiconductor Quantum Dots and Its Biosensing Applications: A Comprehensive Review

Electrochemically Active Materials for Tissue-Interfaced Soft Biochemical Sensing

Tissue-interfaced soft biochemical sensing represents a crucial approach to personalized healthcare by employing electrochemically active materials to monitor biochemical signals at the tissue interface in real time, either noninvasively or through implantation. These soft biochemical sensors can be integrated with various biological tissues, such as neural, gastrointestinal, ocular, cardiac, skin, muscle, and bone, adapting to their unique mechanical and biochemical environments. Sensors employing materials like conductive polymers, composites, metals, metal oxides, and carbon-based nanomaterials have demonstrated capabilities in applications, such as continuous glucose monitoring, neural activity mapping, and real-time metabolite detection, enhancing diagnostics and treatment monitoring across a range of medical fields. Next-generation tissue-interfaced biosensors that enable multimodal and multiplexed measurement of biochemical markers and physiological parameters could be transformative for personalized medicine, allowing for high-resolution, time-resolved historical monitoring of an individual's health status. In this review, we summarize current trends in the field to provide insights into the challenges and future trajectory of tissue-interfaced soft biochemical sensors, highlighting their potential to revolutionize personalized medicine and improve patient outcomes.

Recent advances in the electrochemiluminescence detection of small molecule drugs

The detection of small molecule drugs is crucial in clinical treatment and environmental protection by facilitating the optimization of therapeutic regimens, preventing adverse drug reactions and monitoring environmental pollution. Electrochemiluminescence (ECL) is widely employed in the detection of small molecule drugs due to its high sensitivity and low background signal. This review highlights advancements from the last five years or so in ECL detection methods based on ECL reactions between luminophores and drugs as well as those based on affinity reactions between recognition molecules and drugs. Studies on affinity-based sensors including immunosensors, aptamer sensors, molecularly imprinted sensors, and composite material sensors are summarized. The review reveals that innovations in ECL luminophores, electrode materials and recognition materials are key areas of focus in this field. Nanomaterials play fundamentally important roles in enhancing the performance of ECL detection by acting as carriers of conventional luminophores, highly efficient luminescent materials, catalytically active electrode materials, and selective and stable recognition elements. With further advances in multiple drug detection, instrument miniaturization, on-site and point of care detection, and therapeutic monitoring, ECL is expected to play more significant roles in the detection of small molecule drugs.

Enhanced electrochemiluminescence of CdS QDs encapsulated in IRMOF-3 for sensitive detection of human epithelial protein 4

The advancement of pragmatic and highly-sensitive electrochemiluminescence (ECL) biosensors depends upon signal tags with high and stable signal intensity. Herein, enhanced ECL emission was obtained by encapsulating the dual-stabilizer-capped CdS QDs in a metal-organic framework (MOF), which served as a valid ECL signal tag for detecting biomarkers. Dual-stabilizer-capped CdS QDs reduce dangling bonds on the surface and improved the ECL emission. Furthermore, functionalized isoreticular metal-organic framework-3 (IRMOF-3) can not only load a large quantity of CdS QDs through the encapsulation capability but also serves as a co-reaction accelerator to promote the formation of more SO4•- from the S2O82-, further improving the ECL emission of QDs, while the integrated design of IRMOF-3 co-reaction accelerator and CdS QDs effectively shortens the electron transfer pathway and reduces the energy consumption in ECL system. Using human epithelial protein 4 (HE4) as the model of analysis, the biosensor demonstrated a broad linear range (50 fg mL-1∼50 ng mL-1) and a low detection limit (9.89 fg mL-1) under optimal operating conditions. The study provides an effective and alternative method to improve the ECL efficiency of QDs, significantly broadening their potential applications in sensing analysis, medical diagnostics, and bioimaging.

Recent Advances in Luminophores for Enhanced Electrochemiluminescence Analysis

Electrochemiluminescence (ECL) detection is widely applied in many fields, including chemical measurement, biological analysis, and clinic tests, due to its high sensitivity. Currently, the fast development of many new electrochemical luminophores is continuously improving the ECL-based detection ability. Besides the enhancement of luminescence emission for a high detection sensitivity, minimizing the effect of co-reactants on ECL detection and achieving multiple analysis in one sample are also the main directions in this field. This review focuses on a summary of recently prepared new luminophores to achieve the three aims mentioned above. Especially, the review is composed by three parts, focusing on the luminophores or materials with high ECL efficiency, self-enhancing properties, and multi-color ECL luminophores. The fabrication of biosensors using these molecules is also reviewed to exhibit the advances in biological applications.

Emergence of Quantum Dots as Innovative Tools for Early Diagnosis and Advanced Treatment of Breast Cancer

Quantum dots (QDs) semiconducting nanomaterials, have garnered attention due to their distinctive properties, including small size, high luminescence, and biocompatibility. In the context of triple-negative breast cancer (TNBC), notorious for its resistance to conventional treatments, QDs exhibit promising potential for enhancing diagnostic imaging and providing targeted therapies. This review underscores recent advancements in the utilization of QDs in imaging techniques, such as fluorescence tomography and magnetic resonance imaging, aiming at the early and precise detection of tumors. Emphasis is placed on the significance of QD design, synthesis and functionalization processes as well as their use in innovative strategies for targeted drug delivery, capitalizing on their ability to selectively deliver therapeutic agents to cancer cells. As the research in this field advances rapidly, this review covers a classification of QDs according to their composition, the characterization techniques than can be used to determine their properties and, subsequently, emphasizes recent findings in the field of TNBC-targeting, highlighting the imperative need to address challenges, like potential toxicity or methodologies standardization. Collectively, the findings explored thus far suggest that QDs could pave the way for early diagnosis and effective therapy of TNBC, representing a significant stride toward precise and personalized strategies in treating TNBC.

From theory to practice: understanding the challenges in the implementation of electrogenerated chemiluminescence for analytical applications

Electrogenerated chemiluminescence (ECL) stands out as a remarkable phenomenon of light emission at electrodes initiated by electrogenerated species in solution. Characterized by its exceptional sensitivity and minimal background optical signals, ECL finds applications across diverse domains, including biosensing, imaging, and various analytical applications. This review aims to serve as a comprehensive guide to the utilization of ECL in analytical applications. Beginning with a brief exposition on the theory at the basis of ECL generation, we elucidate the diverse systems employed to initiate ECL. Furthermore, we delineate the principal systems utilized for ECL generation in analytical contexts, elucidating both advantages and challenges inherent to their use. Additionally, we provide an overview of different electrode materials and novel ECL-based protocols tailored for analytical purposes, with a specific emphasis on biosensing applications.

Emerging Applications of Nanobiosensors in Pathogen Detection in Water and Food

Food and waterborne illnesses are still a major concern in health and food safety areas. Every year, almost 0.42 million and 2.2 million deaths related to food and waterborne illness are reported worldwide, respectively. In foodborne pathogens, bacteria such as Salmonella, Shiga-toxin producer Escherichia coli, Campylobacter, and Listeria monocytogenes are considered to be high-concern pathogens. High-concern waterborne pathogens are Vibrio cholerae, leptospirosis, Schistosoma mansoni, and Schistosima japonicum, among others. Despite the major efforts of food and water quality control to monitor the presence of these pathogens of concern in these kinds of sources, foodborne and waterborne illness occurrence is still high globally. For these reasons, the development of novel and faster pathogen-detection methods applicable to real-time surveillance strategies are required. Methods based on biosensor devices have emerged as novel tools for faster detection of food and water pathogens, in contrast to traditional methods that are usually time-consuming and are unsuitable for large-scale monitoring. Biosensor devices can be summarized as devices that use biochemical reactions with a biorecognition section (isolated enzymes, antibodies, tissues, genetic materials, or aptamers) to detect pathogens. In most cases, biosensors are based on the correlation of electrical, thermal, or optical signals in the presence of pathogen biomarkers. The application of nano and molecular technologies allows the identification of pathogens in a faster and high-sensibility manner, at extremely low-pathogen concentrations. In fact, the integration of gold, silver, iron, and magnetic nanoparticles (NP) in biosensors has demonstrated an improvement in their detection functionality. The present review summarizes the principal application of nanomaterials and biosensor-based devices for the detection of pathogens in food and water samples. Additionally, it highlights the improvement of biosensor devices through nanomaterials. Nanomaterials offer unique advantages for pathogen detection. The nanoscale and high specific surface area allows for more effective interaction with pathogenic agents, enhancing the sensitivity and selectivity of the biosensors. Finally, biosensors' capability to functionalize with specific molecules such as antibodies or nucleic acids facilitates the specific detection of the target pathogens.