1,720,954 research outputs found
Fluorescence-doped silica nanoparticles for ultrasensitive detection of prostate specific antigen
Get PDFProstate cancer (PCa) is the topmost diagnosed cancer in males in South Africa according to the National Cancer Registry 2020, affecting both adolescent and young adult men. Currently, PCa is diagnosed using the dreaded digital rectal examination (DRE) followed by tissue biopsy, and prostate-specific antigen (PSA) test for confirmation. DRE is an invasive method and can detect PCa in late stages when the tumour has formed. Therefore, there is a need for early diagnosis technology, that can detect PCa during carcinogenesis. PSA test offers this opportunity even though it is non-specific. This test is a non-invasive, well-established, and conventional method used as a confirmatory test. However, the test suffers from shortfalls like the misdiagnosis of benign prostatic hyperplasia (BPH) or prostatitis as prostate cancer. In this work, we have developed an ultrasensitive fluorescence-based PSA test based on the oriented immobilization of anti-PSA monoclonal and polyclonal antibodies. Anti-PSA polyclonal antibodies (anti-PSA-pAb) were bioconjugated via boronate ester onto the fluorescein-5-isothiocyanate (FITC) doped silica nanoparticles for detection. Anti-PSA monoclonal antibodies were used as capture antibodies on dark fluorescence microplate or magnetic nanoparticles. A sandwich immunoassay was used for the detection of PSA. The anti-PSA-pAb was bioconjugated on the surface of the FITC-doped silica nanoparticles. In the design, the FITC-(3-aminopropyl)triethoxysilane (APTES) organosilane precursor was encapsulated into the silica nanoparticles to form fluorescent silica nanoparticles (FITC@SiO2NPs). The silica shell prevented dye leakage and promoted fluorescent signal amplification. Optimization of the as-prepared fluorescent silica nanoparticles was investigated at altered FITC-dye loadings of 3.0% and 6.0% (for high loading). The fluorescent silica nanobioconjugates exhibited a strong excitation-dependent emission property at 518 nm and was photostable over time. The fluorescent silica nanoparticles exhibited 65% dye loading for both 3.0% and 6.0% silica nanoparticles respectively for 30 ± 3 nm and 46 ± 2 nm. The fluorescent nanobioconjugates’ performance was evaluated using black 96-well microplates. A fluorescence sandwich-type immunoreaction was achieved via the antibody-antigen reaction of the FITC@SiO2-prAmPBA-anti-PSA-pAb/glucose nanobioconjugates binding to the captured PSA analyte. NaOH was used for alkali hydrolysis of the sensing nanobioconjugates to release the FITC-APTES molecules, leading to fluorescence signal amplification. The proposed fluorescence immunobiosensor exhibited a linear relationship between the fluorescent signals and the concentration of PSA obtained in the range of 2.0 pg.mL-1 to 50 ng.mL-1, with excellent limit of detection and limit of quantification both in the pg.mL-1 range in PBS buffer (pH 7.4) and PSA in spiked serum samples. The immunosensor was based on the immunometric sandwich protocol, using nanomagnetic-silica antibody bioconjugates for capture and fluorescent nanobioconjugates as sensing probes. The use of nanomagnetic-silica antibody bioconjugates allowed concentration of PSA as the analyte and ease of separation using a magnet. Alkali hydrolysis of the sensing fluorescent nanobioconjugates is achieved using NaOH, resulting in the release of FITC molecules and an amplified fluorescence detection signal. The analytical performance of the proposed fluorescence immunobiosensor exhibited a linear relationship between the fluorescent signals and the concentration of PSA obtained in the range of 2.0 pg.mL-1 to 100 ng.mL-1, with excellent limit of detection and limit of quantification both in the pg.mL-1 range in PBS buffer (pH 7.4) and PSA in spiked serum samples. The immunosensor also exhibited good specificity and selectivity for PSA with 94.8% - 102.5% recovery rates. The proposed fluorescence immunoassay exhibited high selectivity and specificity for the detection of PSA.Thesis (MSc) -- Faculty of Science, Chemistry, 202
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Antibody fluorescein-doped silica nanobioconjugates for the ultrasensitive detection of prostate-specific antigen
Get PDFHerein, we report the bioconjugation of anti-prostate-specific antigen polyclonal antibodies (pAb) onto the fluorescein-doped silica nanoparticles to detect prostate-specific antigen (PSA). Fluorescein-isothiocyanate (FITC), a fluorescent dye, was reacted with (3-aminopropyl)triethoxysilane (APTES) to form the FITC-APTES organosilane precursor. FITC-APTES was mixed with tetraethoxysilane (TEOS) to form fluorescent silica nanoparticles (FITC@SiO 2NPs) containing 3% and 6% of dye loading. The silica nanoparticles prevented the dye from leaching and promoted the fluorescent signal amplification for the detection of PSA. Phenylboronic acid (PBA) was coated onto the fluorescent silica nanoparticles for the oriented antibody immobilization via the boronate ester to form FITC@SiO 2-PBA-pAb. The fluorescent silica nanobioconjugates exhibited an emission peak at 518 nm, which was stable over time. A fluorescence sandwich-type immunoassay was used for the detection of PSA using FITC@SiO 2-PBA-pAb. Alkaline hydrolysis of the sensing nanobioconjugates afforded enhanced sensitivity by releasing FITC molecules. In buffer samples, the fluorescent immunosensor exhibited a linear correlation range from 2.0 pg mL −1 to 50 ng mL −1. The linear range was from 2.0 pg mL −1 to 100 ng mL −1 in newborn calf serum (representing real samples). The limit of detection (LOD) was 8.25 fg mL −1 with a limit of quantification (LOQ) of 27.2 fg mL −1 in PBS (pH 7.4) after NaOH dissolution. A fluorescence immunosensor was used to detect PSA in spiked newborn calf serum with NaOH dissolution. It exhibited an LOD value of 33.0 fg mL −1 and LOQ value of 0.109 pg mL −1. The developed fluorescence immunosensor showed high selectivity and specificity for PSA. The detection of prostate-specific antigen in newborn calf serum samples exhibited no matrix interferences.</p
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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