Dual-Aptamer Recognition of DNA Logic Gate Sensor-Based Specific Exosomal Proteins for Ovarian Cancer Diagnosis

Biosensor-based methods for exosome detection with applications to disease diagnosis

Exosomes are nanoscale extracellular vesicles (EVs) secreted by most eukaryotic cells and can be found in nearly all human body fluids. Increasing evidence has revealed their pivotal roles in intercellular communication, and their active participation in myriad physiological and pathological activities. Exosomes' functions rely on their contents that are closely correlated with the biological characteristics of parental cells, which may provide a rich resource of molecular information for accurate and detailed diagnosis of a diverse array of diseases, such as differential diagnosis of Alzheimer's disease, early detection and subtyping of various tumors. As a category of sensitive detection devices, biosensors can fully reveal the molecular information and convert them into actionable clinical information. In this review, recent advances in biosensor-based methods for the detection of exosomes are summarized. We have described the fabrication of various biosensors based on the analysis of exosomal proteins, RNAs or glycans for accurate diagnosis, with respect to their elaborate recognition designs, signal amplification strategies, sensing properties, as well as their application potential. The challenges along with corresponding technologies in the future development and clinical translation of these biosensors are also discussed.

AND logic gate-based alternating PER-Cas12a signal amplification system for ultrasensitive detection of sEVs

Protein biomarkers on breast cancer-derived small extracellular vesicles (BC-sEVs) hold great promise in liquid biopsy. However, it remains challenging due to their inherent heterogeneity and low abundance. Herein, we developed an AND logic gate-based DNA cascade signal amplification strategy, termed Alternating Primer Exchange Reaction-activated Cas12a (Alt-PER-Cas12a), for the ultrasensitive detection of BC-sEVs in clinic samples. This dual-protein recognition system employs EpCAM/MUC1-specific capture probes to release two DNA hairpins (Hep and Hmu) as AND gate inputs in Alt-PER. The corresponding Hep and Hmu hairpins can initiate the Alt-PER with a large amount of primers to generate long single-stranded DNA products with alternating repeat units. Each repeating unit serves as a CRISPR activator, inducing the trans-cleavage activity of Cas12a and enabling cascade signal amplification. The as-constructed strategy exhibits excellent sensitivity with LOD of 2.6 × 103 particles/mL. It has been successfully used to discriminate breast cancer patients from healthy donors (AUC = 0.992) in clinical validation, and shows great potential for liquid biopsy.

Exosome biosensors for detection of prostate cancer

Prostate cancer (PCa) is a highly life-threatening disease in men, causing numerous deaths worldwide. As PCa is often diagnosed at a late stage, current diagnostic methods can be invasive and sometimes lead to unnecessary treatments. Therefore, new non-invasive approaches are needed to detect biomarkers for more rapid and accurate PCa diagnosis. Exosomes, extracellular vesicles, provide valuable insights into cellular health and disease progression. Recent studies have indicated the potential use of exosomes as biomarkers for diagnosing PCa. Developing fast, reliable, and sensitive methods for exosome detection is essential. Biosensors, powerful analytical tools for biological samples, have become increasingly crucial in exosome analysis. This review summarizes recent advancements in biosensor technology for exosome detection and provides insights into future perspectives. The goal is to encourage innovative biosensor-based approaches for exosome detection and contribute to the early diagnosis and clinical monitoring of various diseases.

A Patient-Centered Approach in Sensor Science: Embracing Patient Engagement for Translational Clinical Technologies

With the goal of impacting patient quality of life and outcomes, sensor science offers significant potential to revolutionize healthcare by providing advances in the detection of molecular biomarkers for personalized clinical technologies. The sensor community has achieved significant technical advancements that can impact diagnostics, health monitoring, and disease treatment; however, many sensor innovations remain confined to the laboratory, failing to bridge the translational gap between research and real-world clinical applications. This perspective presents a new direction for the sensor community, where sensor development centers on the needs and experiences of the primary beneficiaries: the patients. We provide guidelines and resources for researchers to engage with patients early and continuously throughout the research process to inform sensor specifications and better align sensor technologies with real-world clinical needs, improving their adoption and impact. We also present examples for implementing a patient-centered approach in sensor development and planning for patient engagement in sensor research. In the design of impactful sensors for patients, researchers must expand focus beyond technical specifications to embrace a patient-centered approach, which will likely lead to new opportunities for collaboration and evolution in the sensor science community.

Computation-Enabled Structure-Based Discovery of Potent Binders for Small-Molecule Aptamers

Aptamers, functional nucleic acids recognized for their high target-binding affinity and specificity, have been extensively employed in biosensors, diagnostics, and therapeutics. Conventional screening methods apply evolutionary pressure to optimize affinity, while counter-selections are used to minimize off-target binding and improve specificity. However, aptamer specificity characterization remains limited to target analogs and experimental controls. A systematic exploration of the chemical space for aptamer-binding chemicals (targets) is crucial for uncovering aptamer versatility and enhancing target specificity in practical applications, a task beyond the scope of experimental approaches. To address this, we employed a high-throughput three-stage structure-based computational framework to identify potent binders for two model aptamers. Our findings revealed that the l-argininamide (L-Arm)-binding aptamer has a 31-fold higher affinity for the retromer chaperone R55 than for L-Arm itself, while guanethidine and ZINC10314005 exhibited comparable affinities to L-Arm. In another case, norfloxacin and difloxacin demonstrated over 10-fold greater affinity for the ochratoxin A (OTA)-binding aptamer OBA3 than OTA, introducing a fresh paradigm in aptamer-target interactions. Furthermore, pocket mutation studies highlighted the potential to tune aptamer specificity, significantly impacting the bindings of L-Arm or norfloxacin. These findings demonstrate the effectiveness of our computational framework in discovering potent aptamer binders, thereby expanding the understanding of aptamer-binding versatility and advancing nucleic acid-targeted drug discovery.

Exosomal ncRNAs in reproductive cancers†

Extracellular vesicles, particularly exosomes, play a pivotal role in the cellular mechanisms underlying cancer. This review explores the various functions of exosomes in the progression, growth, and metastasis of cancers affecting the male and female reproductive systems. Exosomes are identified as key mediators in intercellular communication, capable of transferring bioactive molecules such as microRNAs, proteins, and other nucleic acids that influence cancer cell behavior and tumor microenvironment interactions. It has been shown that non-coding RNAs transported by exosomes play an important role in tumor growth processes. Significant molecules that may serve as biomarkers in the development and progression of male reproductive cancers include miR-125a-5p, miR-21, miR-375, the miR-371 ~ 373 cluster, and miR-145-5p. For female reproductive cancers, significant microRNAs include miR-26a-5p, miR-148b, miR-205, and miRNA-423-3p. This review highlights the potential of these noncoding RNAs as biomarkers and prognostics in tumor diagnostics. Understanding the diverse roles of exosomes may hold promise for developing new therapeutic strategies and improving treatment outcomes for cancer patients.

Exosomes in cancer diagnosis based on the Latest Evidence: Where are We?

Exosomes are small extracellular vesicles (EVs) derived from various cellular sources and have emerged as favorable biomarkers for cancer diagnosis and prognosis. These vesicles contain a variety of molecular components, including nucleic acids, proteins, and lipids, which can provide valuable information for cancer detection, classification, and monitoring. However, the clinical application of exosomes faces significant challenges, primarily related to the standardization and scalability of their use. In order to overcome these challenges, sophisticated methods such as liquid biopsy and imaging are being combined to augment the diagnostic capabilities of exosomes. Additionally, a deeper understanding of the interaction between exosomes and immune system components within the tumor microenvironment (TME) is essential. This review discusses the biogenesis and composition of exosomes, addresses the current challenges in their clinical translation, and highlights recent technological advancements and integrative approaches that support the role of exosomes in cancer diagnosis and prognosis.

Sensitive and Cost-Effective Tools in the Detection of Ovarian Cancer Biomarkers

Women diagnosed with late-stage ovarian cancer suffer a very high rate of mortality. Accordingly, it is imperative to detect and diagnose the disease as early as possible in its development. Achievement of this aim implies relatively large-scale screening of women at an age of clinical significance through assay of biomarkers for disease present in blood or serum. Biosensor detection offers an attractive technology for the automated detection of such species. Among several biomarkers that have been identified that are present in patients with ovarian cancer, the only one that is commonly tested for in clinical use is cancer antigen 125, which is considered to be a poor biomarker for the disease. Here, we describe several biosensors that developed in the past decade for the detection of ovarian cancer biomarkers such as CA125, human epididymis protein 4 (HE4) and apolipoprotein A1. The challenges presented by the fabrication of biosensor devices for detecting ovarian cancer and the limited number of biosensors developed for this purpose are discussed.

In Situ, Fusion-Free, Multiplexed Detection of Small Extracellular Vesicle miRNAs for Cancer Diagnostics

Tumor-derived small extracellular vesicle (sEV) microRNAs (miRNAs) are emerging biomarkers for cancer diagnostics. Conventional sEV miRNA detection methods necessitate the lysis of sEVs, rendering them laborious and time-consuming and potentially leading to damage or loss of miRNAs. Membrane fusion-based in situ detection of sEV miRNAs involves the preparation of probe-loaded vesicles (e.g., liposomes or cellular vesicles), which are typically sophisticated and require specialist equipment. Membrane perforation methods employ chemical treatments that can induce severe miRNA degradation or leaks. Inspired by previous studies that loaded nucleic acids into EVs or cells using hydrophobic tethers for therapeutic applications, herein, we repurposed this strategy by conjugating a hydrophobic tether onto molecular beacons to aid their transportation into sEVs, allowing for in situ detection of miRNAs in a fusion-free and multiplexing manner. This method enables simultaneous detection of multiple miRNA species within serum-derived sEVs for the diagnosis of prostate cancer, breast cancer, and gastric cancer with an accuracy of 83.3%, 81.8%, and 100%, respectively, in a cohort of 66 individuals, indicating that it holds a high application potential in clinical diagnostics.

Increasing the sensitivity and accuracy of detecting exosomes as biomarkers for cancer monitoring using optical nanobiosensors

The advancement of nanoscience and material design in recent times has facilitated the creation of point-of-care devices for cancer diagnosis and biomolecule sensing. Exosomes (EXOs) facilitate the transfer of bioactive molecules between cancer cells and diverse cells in the local and distant microenvironments, thereby contributing to cancer progression and metastasis. Specifically, EXOs derived from cancer are likely to function as biomarkers for early cancer detection due to the genetic or signaling alterations they transport as payload within the cancer cells of origin. It has been verified that EXOs circulate steadily in bodily secretions and contain a variety of information that indicates the progression of the tumor. However, acquiring molecular information and interactions regarding EXOs has presented significant technical challenges due to their nanoscale nature and high heterogeneity. Colorimetry, surface plasmon resonance (SPR), fluorescence, and Raman scattering are examples of optical techniques utilized to quantify cancer exosomal biomarkers, including lipids, proteins, RNA, and DNA. Many optically active nanoparticles (NPs), predominantly carbon-based, inorganic, organic, and composite-based nanomaterials, have been employed in biosensing technology. The exceptional physical properties exhibited by nanomaterials, including carbon NPs, noble metal NPs, and magnetic NPs, have facilitated significant progress in the development of optical nanobiosensors intended for the detection of EXOs originating from tumors. Following a summary of the biogenesis, biological functions, and biomarker value of known EXOs, this article provides an update on the detection methodologies currently under investigation. In conclusion, we propose some potential enhancements to optical biosensors utilized in detecting EXO, utilizing various NP materials such as silicon NPs, graphene oxide (GO), metal NPs, and quantum dots (QDs).

Exosomes in the Diagnosis of Neuropsychiatric Diseases: A Review

Exosomes are 30-150 nm small extracellular vesicles (sEVs) which are highly stable and encapsulated by a phospholipid bilayer. Exosomes contain proteins, lipids, RNAs (mRNAs, microRNAs/miRNAs, long non-coding RNAs/lncRNAs), and DNA of their parent cell. In pathological conditions, the composition of exosomes is altered, making exosomes a potential source of biomarkers for disease diagnosis. Exosomes can cross the blood-brain barrier (BBB), which is an advantage for using exosomes in the diagnosis of central nervous system (CNS) diseases. Neuropsychiatric diseases belong to the CNS diseases, and many potential diagnostic markers have been identified for neuropsychiatric diseases. Here, we review the potential diagnostic markers of exosomes in neuropsychiatric diseases and discuss the potential application of exosomal biomarkers in the early and accurate diagnosis of these diseases. Additionally, we outline the limitations and future directions of exosomes in the diagnosis of neuropsychiatric diseases.