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Extracellular vesicles (EVs) have shown great potential as biomarkers since they reflect the physio-pathological status of the producing cell. In the context of cytotoxicity, it has been found that exposing cells to toxicants leads to changes in protein expression and the cargo of the EVs they produce. Here, we studied large extracellular vesicles (lEVs) derived from human microvascular endothelial cells (HMEC-1) to detect the modifications induced by cell exposure to benzo[a]pyrene (B[a]P). We used a custom CaF2-based biochip which allowed hyphenated techniques of investigation: surface plasmon resonance imaging (SPRi) to monitor the adsorption of objects, atomic force microscopy (AFM) to characterise EVs' size and morphology, and Raman spectroscopy to detect molecular modifications. Results obtained on EVs by Raman microscopy and tip-enhanced Raman spectroscopy (TERS) showed significant differences induced by B[a]P in the high wavenumber region of Raman spectra (2800 to 3000 cm−1), corresponding mainly to lipid modifications. Two types of spectra were detected in the control sample. A support vector machine (SVM) model was trained on the pre-processed spectral data to differentiate between EVs from cells exposed or not to B[a]P at the spectrum level; this model could achieve a sensitivity of 88% and a specificity of 99.5%. Thus, this experimental setup facilitated the distinction between EVs originating from two cell culture conditions and enabled the discrimination of EV subsets within one cell culture condition. [ABSTRACT FROM AUTHOR]

Early detection of ovarian cancer (OC) is crucial for effective management and treatment, as well as reducing mortality rates. However, the current diagnostic methods for OC are time-consuming and have low accuracy. Surface plasmon resonance (SPR) biosensors offer a promising alternative to conventional techniques, as they enable rapid and less invasive screening of various circulating indicators. These biosensors are widely used for biomolecular interaction analysis and detecting tumor markers, and they are currently being investigated as a rapid diagnostic tool for early-stage cancer detection. Our main focus is on the fundamental concepts and performance characteristics of SPR biosensors. We also discuss the latest advancements in SPR biosensors that enhance their sensitivity and enable high-throughput quantification of OC biomarkers, including CA125, HE4, CEA, and CA19-9. Finally, we address the future challenges that need to be overcome to advance SPR biosensors from research to clinical applications. The ultimate goal is to facilitate the translation of SPR biosensors into routine clinical practice for the early detection and management of OC. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative viral pathogen in the coronavirus disease 2019 (COVID-19) pandemic, which prompted an immediate global response to the development of vaccines and antiviral therapeutics. Drug repurposing in antiviral therapeutics allows for the rapid advancement of existing clinical candidates and therapies into human clinical trials to be tested as COVID-19 therapies. Screening method for drug repurposing are required to prepare the next emerging infectious diseases. In the present study, surface plasmon resonance imaging (SPRi) technique was used to find drug repositioning candidates by taking SARS-CoV2 as an example. Preventing viral entry is an effective antiviral treatment strategy used early during symptom onset. SARS-CoV-2 enters angiotensin-converting enzyme 2 (ACE2)-expressing cells when the receptor-binding domain of the spike protein on the surface of SARS-CoV-2 binds to ACE2, followed by cleavage at two cut sites by transmembrane protease, serine 2 (TMPRSS2). Therefore, a molecule capable of inhibiting the protease activity of TMPRSS2 could be a valuable antiviral therapy. We evaluated whether it was possible to detect specific binding by measuring interactions of drugs and TMPRSS2. In a result, ulinastatin bound with recombinant TMPRSS2 immobilized on biochips pH-dependently. These results suggested that SPRi can be useful technique to discover drug repositioning candidates without in vitro assay, which contributes to the rapid screening. [ABSTRACT FROM AUTHOR]

The work reports the combination of basic digital image processing (DIP) techniques and statistical segmentation strategy (SDS) to improve surface plasmon resonance curve (SPRc) and SPR imaging (SPRi) sensors' performance. The SPR image is used for sensing and monitoring biological events in the so-called SPR imaging process. In the traditional SPR process based on the attenuated total reflection (ATR) method, the image is used to create the SPR curve, and the curve features tracking is employed on sensing applications. The SPR curve features are enhanced after the pixels of the SPR image have been processed with low-complexity filters in the spatial domain (brightness, contrast, threshold, and morphological). The bootstrap was used as a statistical processing approach, selecting lines and columns from the image that was less affected by imperfections and noises in the image detector, and consequently reducing the SPR sensor instrumentation disturbances. Experimental tests with reversible binding water-mixture were performed, and both image and statistical processing were reported. The combination of DIP and SDS approaches improves the extraction of the curve features, increasing the performance in terms of resonance position sensitivity to 81%. [ABSTRACT FROM AUTHOR]

Podoplanin (PDP) is a small transmembrane protein and widely present in various specialized cells throughout the human body. It is a specific marker for identification of lymphatic vessel and a candidate marker for cancer stem cells in squamous cell carcinoma of the lung. We report on method for the highly selective determination of PDP by using a surface plasmon resonance imaging (SPRI) that exploits the highly selective interaction between PDP and anti-human PDP monoclonal antibody (IgG). The sensor has a dynamic range between 0.25 and 1.0 ng mL, and a detection limit of 15 pg mL. It was applied to the determination of PDP in blood plasma and tissue homogenates from paired normal and lung tumor tissue. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The 20S proteasome is a multicatalytic enzyme complex responsible for intracellular protein degradation in mammalian cells. Its antigen level or enzymatic activity in blood plasma are potentially useful markers for various malignant and nonmalignant diseases. We have developed a method for highly selective determination of the 20S proteasome using a Surface Plasmon Resonance Imaging (SPRI) technique. It is based on the highly selective interaction between the proteasome's catalytic β5 subunit and immobilized inhibitors (the synthetic peptide PSI and epoxomicin). Inhibitor concentration and pH were optimized. Analytical responses, linear ranges, accuracy, precision and interferences were investigated. Biosensors based on either PSI and epoxomicin were found to be suitable for quantitative determination of the proteasome, with a precision of ±10% for each, and recoveries of 102% and 113%, respectively, and with little interference by albumin, trypsin, chymotrypsin, cathepsin B and papain. The proteasome also was determined in plasma of healthy subjects and of patients suffering from acute leukemia. Both biosensors gave comparable results (2860 ng·mL-1 on average for control, and 42300 ng·mL-1 on average for leukemia patients). [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Gold-silver bimetallic film configuration is brought forward to realize surface plasmon resonance imaging (SPRI) biosensor with the virtues of both high sensitivity and chemical stability. The theoretical calculation is adopted to optimize the thicknesses of the metal films, and bimetallic film configuration with high refractive index sensitivity and a good linearity between reflectivity and refractive index is presented. Then, the property of the detection system is discussed. The results show that in comparison to most commercial SPRI biosensors which use single gold films, the sensitivity and molecule detection ability of the gold-silver bimetallic film configuration can be improved to a great extent. For the substrate of BAK3 glass used in this paper, the sensitivity enhancement reaches as high as 80%, which makes it a much better choice for SPRI biosensing applications. [ABSTRACT FROM AUTHOR]

Sensors able to provide ‘yes’/‘no’ answers have become of interest in recent years, especially in the fields of environmental research and healthcare. We describe a procedure based on surface plasmon resonance imaging (SPRI) to investigate the interaction between mucin and anti-mucin antibody, and we outline the development of an alarm sensor for the protein mucin, whose high concentration in saliva, blood or tissue is related to illnesses such as gingivitis, peridontitis or even cancer. Anti-mucin gastric antibodies are immobilised onto a gold surface. The immobilisation is evaluated for neat gold chips and for polymer-modified gold surfaces. We found that two different pHs are required, one for the immobilisation of the antibodies on gold (pH 5.5) and a different one for optimal interaction between the sample and the antibody layer (pH 7.0). Finally, we briefly demonstrate the application of the sensor to real saliva samples, both mucin-less and mucin-containing, evaluating the potential of the sensor to discriminate between healthy and ill. [ABSTRACT FROM AUTHOR]