PD-L1 exosomes electrochemical sensor based on coordination of AgNCs and Zr4+: Multivalent peptide enhancing target capture efficiency and antifouling performance

Lectin microarray based glycan profiling of exosomes for dynamic monitoring of colorectal cancer progression

BACKGROUND

Exosomes, as emerging biomarkers in liquid biopsies in recent years, offer profound insights into cancer diagnostics due to their unique molecular signatures. The glycosylation profiles of exosomes have emerged as potential biomarkers, offering a novel and less invasive method for cancer diagnosis and monitoring. Colorectal cancer (CRC) represents a substantial global health challenge and burden. Thus there is a great need for the aberrant glycosylation patterns on the surface of CRC cell-derived exosomes, proposing them as potential biomarkers for tumor characterization.

RESULTS

The interactions of 27 lectins with exosomes from three CRC cell lines (SW480, SW620, HCT116) and one normal colon epithelial cell line (NCM460) have been analyzed by the lectin microarray. The result indicates that Ulex Europaeus Agglutinin I (UEA-I) exhibits high affinity and specificity towards exosomes derived from SW480 cells. The expression of glycosylation related genes within cells has been analyzed by high-throughput quantitative polymerase chain reaction (HT-qPCR). The experimental result of HT-qPCR is consistent with that of lectin microarray. Moreover, the limit of detection (LOD) of UEA-I microarray is calculated to be as low as 2.7 × 105 extracellular vehicles (EVs) mL-1 (three times standard deviation (3σ) of blank sample). The UEA-I microarray has been successfully utilized to dynamically monitor the progression of tumors in mice-bearing SW480 CRC subtype, applicable in tumor sizes ranging from 2 mm to 20 mm in diameter.

SIGNIFICANCE

The results reveal that glycan expression pattern of exosome is linked to specific CRC subtypes, and regulated by glycosyltransferase and glycosidase genes of mother cells. Our findings illuminate the potential of glycosylation molecules on the surface of exosomes as reliable biomarkers for diagnosis of tumor at early stage and monitoring of cancer progression.

Single-atom Zr-doped CoOOH with enhanced electrical conductivity as a signal amplifier and detection probe for the indirect non-enzymatic electrochemical determination of malathion in foods

Herein, a novel electrochemical sensor based on zirconium-doped cobalt oxyhydroxide (ZrCoOOH) was proposed for highly sensitive non-enzymatic determination of malathion (MAL). The doping of Zr can improve the electrical conductivity of CoOOH, of which the transfer resistance was reduced from 241.1 Ω to 140.2 Ω. Furthermore, the X-ray photoelectron spectroscopy confirmed that part of Co2+ was converted to Co3+ due to the introduction of Zr. The Co3+ in ZrCoOOH could react with MAL to form Co2+, which enhanced the electrooxidation current of Co2+. Therefore, the peak current of Co2+ was served as detection probe for MAL. Under optimal conditions, the developed sensor established the linear relationship for MAL in the concentration range of 0.001-10.0 μM with a low limit of detection (0.64 nM). The constructed sensor was employed to detect MAL in food samples (peach, kiwi fruit, spinach and tomato), verifying the accuracy and practicability of the sensor.

Interface-Engineered 2D Heterojunction with Photoelectric Dual Gain: Mxene@MOF-Enhanced SPR Spectroscopy for Direct Sensing of Exosomes

MXene is widely used in the construction of optoelectronic interfaces due to its excellent properties. However, the hydrophilicity and metastable surface of MXene lead to its oxidation behavior, resulting in the degradation of its various properties, which seriously limits its practical application. In this work, a 2D metal-organic framework (2D MOF) with matching 2D morphology, excellent stability performance, and outstanding optoelectronic performance is grown in situ on the MXene surface through heterojunction engineering to suppress the direct contact between reactive molecules and the inner layer material without affecting the original advantages of MXene. The photoelectric dual gain MXene@MOF heterojunction is confirmed. As a photoelectric material, its properties are highly suitable for the demand of interface sensitization layer materials of surface plasmon resonance (SPR). Therefore, using SPR as a platform for the application of this interface material, the performance of MXene@MOF and its potential mechanism to enhance SPR are analyzed in depth using experiments combined with simulation calculations (FDTD/DFT). Finally, the MXene@MOF/peptides-SPR sensor is constructed for rapid and sensitive detection of the cancer marker exosomes to explore its potential in practical applications. This work offers a forward-looking strategy for the design of interface materials with excellent photoelectric performance.

Coaxial dual-path electrochemical biosensing and logic strategy-based detection of lung cancer-derived exosomal PD-L1

Exosomal programmed death ligand-1 (ExoPD-L1) is a vital marker of immune activation in the early stages of tumor therapy and it can inhibit anti-tumor immune responses. However, due to the low expression of ExoPD-L1 in cancer cells, it is difficult to perform highly sensitive assays and accurately differentiate cancer sources. Therefore, we constructed a coaxial dual-path electrochemical biosensor for highly accurate identification and detection of ExoPD-L1 from lung cancer based on chemical-biological coaxial nanomaterials and nucleic acid molecular signal amplification strategies. The measurements showed that the detected ExoPD-L1 concentrations ranged from 6 × 102 particles per mL to 6 × 108 particles per mL, and the detection limit was 310 particles per mL. Compared to other sensors, the electrochemical biosensor designed in this study has a lower detection limit and a wider detection range. Furthermore, we also successfully identified lung cancer-derived ExoPD-L1 by analyzing multiple protein biomarkers expressed on exosomes through the "AND" logic strategy. This sensor platform is expected to realize highly sensitive detection and accurate analysis of multiple sources of ExoPD-L1 and provide ideas for the clinical detection of ExoPD-L1.

Application of Aptamer-SERS Nanotags for Unveiling the PD-L1 Immunomarker Progression Correlated to the Cell Metabolic Bioprocess

In recent years, the expression and progression of programmed cell death ligand 1 (PD-L1) as an immunomarker in the context of a cell metabolic environment has gained significant attention in cancer research. However, intercellular bioprocesses that control the dynamics of PD-L1 have been largely unexplored. This study aimed to explore the cell metabolic states and conditions that govern dynamic variations of PD-L1 within the cell metabolic environment using an aptamer-based surface-enhanced Raman scattering (SERS) approach. The aptamer-SERS technique offers a sensitive, rapid, and powerful analytical tool for targeted and nondestructive detection of an immunomarker with high sensitivity and specificity. By combining aptamer-SERS with cell state profiling, we investigated the modulation in PD-L1 expression under different metabolic states, including glucose deprivation, metabolic coenzyme activity, and altered time/concentration-based cytokine availability. The most intriguing features in our findings include the cell-specific responses, cell differentiation by revealing distinct patterns, and dynamics of PD-L1 in different cell lines. Additionally, the time-dependent variations in PD-L1 expression, coupled with the dose-dependent relationship between glucose concentration and PD-L1 levels, underscore the complex interplay between immune checkpoint regulation and cellular metabolism. Therefore, this work demonstrates the advantages of using highly-sensitive and specific aptamer-SERS nanotags for investigating the immune checkpoint dynamics and related metabolic bioprocess.

DNA four-way junction-driven dual-rolling circle amplification sandwich-type aptasensor for ultra-sensitive and specific detection of tumor-derived exosomes

There is an urgent need to accurately quantify tumor-derived exosomes, which have emerged as promising non-invasive tumor diagnostic biomarkers. Herein, a bispecific-aptamer sandwich-type gold nanoparticle-modified electrochemical aptasensor was developed based on a four-way junction (4-WJ)-triggered dual rolling circle amplification (RCA)-assisted methylene blue (MB)/G-quadruplex strategy for extremely specific and sensitive exosome detection. This aptamer/exosome/aptamer sandwich-type design contained a CD63-specific aptamer and a cancerous mucin-1 (MUC1) protein-specific aptamer. The CD63 aptamer modified on a gold electrode captured exosomes, and then the sandwich-type aptasensor was formed with the addition of the MUC1 aptamer. The MUC1 aptamer's 3'-end sequence facilitated the formation of 4-WJ, assisted by a molecular beacon probe and a binary DNA probe. Subsequently, a dual-RCA reaction was triggered by binding to two cytosine-rich circle DNA templates at both ends of 4-WJ. Ultimately, dual-RCA products containing multiple G-quadruplex conformations were generated with the assistance of K+ to trap abundant MB indicators and amplify electrochemical signals. The aptasensor exhibited high specificity, sensitivity, repeatability, and stability toward MCF-7-derived exosomes, with a detection limit of 20 particles/mL and a linear range of 1 × 102 to 1 × 107 particles/mL. Moreover, it showed excellent applicability in clinical settings to recover exosomes in normal human serum. Our aptasensor is anticipated to serve as a versatile platform for detecting various specific aptamer-based targets in biomedical and bioanalytical applications.