scholarly journals Biosensor Based Immunoassay: A New Approach for Serotyping of Toxoplasma gondii

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2065
Author(s):  
Susana Sousa ◽  
António Castro ◽  
José Manuel Correia da Costa ◽  
Eulália Pereira
Keyword(s):  
Gold Nanoparticles ◽  
Toxoplasma Gondii ◽  
Point Of Care ◽  
Colorimetric Method ◽  
Type Ii ◽  
Serum Samples ◽  
Experimental Conditions ◽  
New Approach ◽  
New Methodologies ◽  
Definition Of

Toxoplasmosis is the most reported parasitic zoonosis in Europe, with implications in human health and in the veterinary field. There is an increasing need to develop serotyping of Toxoplasma gondii (T. gondii) in view of greater sensitivity and efficiency, through the definition of new targets and new methodologies. Nanotechnology is a promising approach, with impact in the development of point-of-care devices. The aim of this work was to develop a simple but highly efficient method for Toxoplasma gondii serotyping based on gold nanoparticles. A simple colorimetric method was developed using gold nanoparticles modified with the synthetic polymorphic peptide derived from GRA6 antigen specific for type II T. gondii. The method of preparation of the gold nanoprobes and the experimental conditions for the detection were found to be critical for a sensitive discrimination between positive and negative sera. The optimized method was used to detect antibodies anti-GRA6II both in mice and human serum samples. These results clearly demonstrate that a biosensor-based immunoassay using AuNPs conjugated with polymorphic synthetic peptides can be developed and used as a serotyping device

scholarly journals Sonochemical synthesis of polyoxometalate-stabilized gold nanoparticles for point-of-care determination of acetaminophen levels: preclinical study in an animal model

RSC Advances ◽  
2020 ◽  
Vol 10 (28) ◽  
pp. 16805-16816
Author(s):  
Tahereh Rohani Bastami ◽  
Abolphazl Ghaedi ◽  
Scott G. Mitchell ◽  
Aida Javadian-Saraf ◽  
Mohammad Karimi
Keyword(s):  
Gold Nanoparticles ◽  
Animal Model ◽  
Clinical Diagnosis ◽  
Point Of Care ◽  
Preclinical Study ◽  
Sonochemical Synthesis ◽  
Serum Samples ◽  
Over The Counter ◽  
Pharmaceutical Tablets

The aim of this study is the accurate detection of acetaminophen (AP) for point-of-care (POC) clinical diagnosis. The concentration of acetaminophen was measured in over-the-counter pharmaceutical tablets and in serum samples taken from mice.

White-tailed deer (Odocoileus virginianus) are a reservoir of a diversity of Toxoplasma gondii strains in the USA and pose a risk to consumers of undercooked venison

Parasitology ◽  
2020 ◽  
Vol 147 (7) ◽  
pp. 775-781 ◽  
Author(s):  
J. P. Dubey ◽  
C. K. Cerqueira-Cézar ◽  
F. H. A. Murata ◽  
S. K. Verma ◽  
O. C. H. Kwok ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Cell Culture ◽  
Toxoplasma Gondii ◽  
Odocoileus Virginianus ◽  
Type Ii ◽  
Serum Samples ◽  
Modified Agglutination Test ◽  
Pcr Rflp ◽  
The Usa ◽  
Genotype 5

AbstractTo assess the role of white-tailed deer (Odocoileus virginianus, WTD) in the epidemiology of toxoplasmosis, we conducted a national survey of WTD across the USA for Toxoplasma gondii infection. To do this, we combined serology with parasite isolation to evaluate the prevalence and genetic diversity of T. gondii in this game species. From October 2012 to March 2019, serum and tissues were collected from 914 WTD across the USA. Serum samples were screened for antibodies to T. gondii, and then the tissues of seropositive WTD were bioassayed in mice. Antibodies were detected in 329 (36%) of 914 WTD tested by the modified agglutination test (positive reaction at 1:25 or higher). Viable T. gondii was isolated from the heart of 36 WTD from 11 states. Three of the 36 isolates were pathogenic but not highly virulent to outbred Swiss Webster mice and all 36 isolates could be propagated further in cell culture and were genotyped. For genotyping, DNA extracted from cell culture-derived tachyzoites was characterized by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using the genetic markers SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico. Genotyping revealed seven ToxoDB PCR-RFLP genotypes, including 24 isolates for genotype #5 (haplogroup 12), four isolates for #2 (type III, haplogroup 3), three isolates for genotypes #1 (type II, haplogroup 2), two isolates for genotypes #3 (type II, haplogroup 2) and one isolate each for #39, #221 and #224. Genotype #5 was the most frequently isolated, accounting for 66.6% (24 of 36) of the isolates. Combining the 36 isolates from this study with previously reported 69 isolates from WTD, 15 genotypes have been identified. Among these, 50.4% (53/105) isolates belong to genotype #5. Our results indicate moderate genetic diversity of T. gondii in WTD. The results also indicate that undercooked venison should not be consumed by humans or fed to cats.

DETERMINATION OF AMINOGLYCOSIDE ANTIBIOTICS BY A COLORIMETRIC METHOD BASED ON THE AGGREGATION OF GOLD NANOPARTICLES

NANO ◽  
2013 ◽  
Vol 08 (04) ◽  
pp. 1350037 ◽  
Author(s):  
RUIYONG WANG ◽  
SHUMIN FAN ◽  
RUIQIANG WANG ◽  
RUI WANG ◽  
HUANJING DOU ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Incubation Time ◽  
Color Change ◽  
Limit Of Detection ◽  
Colorimetric Method ◽  
Aminoglycoside Antibiotics ◽  
Sensing Element ◽  
Experimental Conditions ◽  
Experimental Parameters

A sensitive and selective colorimetric biosensor for determination of gentamicin, amikacin and tobramycin was proposed with the unmodified gold nanoparticles (GNPs) as the sensing element. Gentamicin, amikacin and tobramycin can rapidly induce the aggregation of gold nanoparticles and is accompanied by a color change from red to blue. The concentration of gentamicin, amikacin and tobramycin can be determined by using UV-Vis spectrometer. The experimental parameters were optimized with regard to pH, incubation time and the concentration of the GNPs. Under optimal experimental conditions, the linear range of the colorimetric sensor for gentamicin/amikacin/tobramycin were 2.67–33.93 ng mL-1, 13.33–66.67 ng mL-1 and 20–180 ng mL-1, respectively. The corresponding limit of detection (3σ) was 0.354 ng mL-1, 0.999 ng mL-1 and 0.579 ng mL-1, respectively. This assay was simple and used to detect aminoglycoside antibiotics in milk and medicine products.

scholarly journals Colorimetric Determination of Sildenafil Citrate (Viagra) Through Ion-Associate Complex Formation

2009 ◽  
Vol 92 (1) ◽  
pp. 125-130 ◽  
Author(s):  
Alaa S Amin ◽  
Moustafa E Moustafa ◽  
Reham M S El-Dosoky
Keyword(s):  
Gentian Violet ◽  
Colorimetric Method ◽  
Sildenafil Citrate ◽  
Colorimetric Determination ◽  
Stoichiometric Ratio ◽  
Serum Samples ◽  
Experimental Conditions ◽  
Complex Species ◽  
Ion Associate

Abstract A simple, quick, accurate, and sensitive colorimetric method is described for the determination of sildenafil citrate (SLD). The method is based on the reaction of SLD with Congo Red, Sudan II, and Gentian Violet in buffered aqueous solutions at pH 2.5, 6.5, and 11.0, respectively, to give highly colored soluble ion-associate complex species; the colored products are quantitated colorimetrically at 523, 554, and 569 nm, respectively. The various experimental conditions were optimized. The stoichiometric ratio was found to be 1:1 for all ion associates; the calculated logarithmic stability constants were 8.51, 7.79, and 5.58, respectively. Beer's law was obeyed over the concentration range of 0.27.0 g/mL, whereas the Ringbom optimum concentration range was 0.46.5 g/mL. Values for molar absorptivity, Sandell sensitivity, and detection and quantification limits were also calculated. The proposed method was successfully applied to the determination of SLD in Viagra tablets and in serum samples by using the technique of standard additions with mean accuracy values of 100.06 1.14, 99.87 0.70, and 99.86 0.97 for Viagra tablets and 99.88 0.60, 99.90 0.90, and 100.24 0.80 for serum samples, respectively.

Head Position Identification

1967 ◽  
Vol 10 (3) ◽  
pp. 438-448
Author(s):  
H. N. Wright
Keyword(s):  
Roc Curve ◽  
Head Position ◽  
Hearing Impaired ◽  
Type Ii ◽  
Experimental Conditions ◽  
Partial Explanation ◽  
Complex Sounds ◽  
Binaural Cues ◽  
Criterion Behavior ◽  
Stimulus Degradation

A binaural recording of traffic sounds that reached an artificial head oriented in five different positions was presented to five subjects, each of whom responded under four different criteria. The results showed that it is possible to examine the ability of listeners to localize sound while listening through earphones and that the criterion adopted by an individual listener is independent of his performance. For the experimental conditions used, the Type II ROC curve generated by manipulating criterion behavior was linear and consistent with a guessing model. Further experiments involving different degrees of stimulus degradation suggested a partial explanation for this finding and illustrated the various types of monaural and binaural cues used by normal and hearing-impaired listeners to localize complex sounds.

Seeing, imagined, and lived

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Anandi Silva Knuppel
Keyword(s):  
Sensory Experience ◽  
Religious Practices ◽  
Daily Lives ◽  
New Approach ◽  
Theories Of Practice ◽  
Sources Of Authority ◽  
Definition Of

Scholarship on Hindu traditions and practices proposes the practice of darshan as fundamental to Hindu traditions, particularly in temple worship, observing that devotees seek out images of deities primarily to see them and “receive” their darshan. These works typically gloss the definition of darshan with a sentence or two about seeing, exchanging glances, and/or receiving blessings. In this paper, I focus on the ways in which darshan is ideally imagined in conjunction with other bodily sensory practices through sources of authority, such as texts and senior devotees, to create a specific sensory experience and expectation in the transnational Gaudiya Vaishnava community. I then look to the lived realitiesof darshan in this tradition, specifically how devotees negotiate the structures created through sources of authority in their daily lives. Through this juxtaposition of idealized and lived darshan, I argue that we need a new approach towards theories of practice to take into account the complexities of darshanic moments in this and other religious practices.

Ferromagnetic Resonance Biosensor for Homogeneous and Volumetric Detection of DNA

2017 ◽  
Author(s):  
Bo Tian ◽  
Peter Svedlindh ◽  
Mattias Strömberg ◽  
Erik Wetterskog
Keyword(s):  
Magnetic Nanoparticles ◽  
Ferromagnetic Resonance ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Rolling Circle Amplification ◽  
Resonance Field ◽  
Isothermal Amplification ◽  
Detection Sensitivity ◽  
Serum Samples ◽  
Rolling Circle

In this work, we demonstrate for the first time, a ferromagnetic resonance (FMR) based homogeneous and volumetric biosensor for magnetic label detection. Two different isothermal amplification methods, <i>i.e.</i>, rolling circle amplification (RCA) and loop-mediated isothermal amplification (LAMP) are adopted and combined with a standard electron paramagnetic resonance (EPR) spectrometer for FMR biosensing. For RCA-based FMR biosensor, binding of RCA products of a synthetic Vibrio cholerae target DNA sequence gives rise to the formation of aggregates of magnetic nanoparticles. Immobilization of nanoparticles within the aggregates leads to a decrease of the net anisotropy of the system and a concomitant increase of the resonance field. A limit of detection of 1 pM is obtained with an average coefficient of variation of 0.16%, which is superior to the performance of other reported RCA-based magnetic biosensors. For LAMP-based sensing, a synthetic Zika virus target oligonucleotide is amplified and detected in 20% serum samples. Immobilization of magnetic nanoparticles is induced by their co-precipitation with Mg<sub>2</sub>P<sub>2</sub>O<sub>7</sub> (a by-product of LAMP) and provides a detection sensitivity of 100 aM. The fast measurement, high sensitivity and miniaturization potential of the proposed FMR biosensing technology makes it a promising candidate for designing future point-of-care devices.<br>

Molecularly Imprinted Sensor for Ascorbic Acid Based on Gold Nanoparticles and Multiwalled Carbon Nanotubes

2020 ◽  
Vol 16 (7) ◽  
pp. 905-913
Author(s):  
Youyuan Peng ◽  
Qingshan Miao
Keyword(s):  
Carbon Nanotubes ◽  
Gold Nanoparticles ◽  
Ascorbic Acid ◽  
Multiwalled Carbon Nanotubes ◽  
Ph Value ◽  
Biological Fluids ◽  
Water Soluble ◽  
Multiwalled Carbon ◽  
Experimental Conditions ◽  
Molecularly Imprinted

Background: L-Ascorbic acid (AA) is a kind of water soluble vitamin, which is mainly present in fruits, vegetables and biological fluids. As a low cost antioxidant and effective scavenger of free radicals, AA may help to prevent diseases such as cancer and Parkinson’s disease. Owing to its role in the biological metabolism, AA has also been utilized for the therapy of mental illness, common cold and for improving the immunity. Therefore, it is very necessary and urgent to develop a simple, rapid and selective strategy for the detection of AA in various samples. Methods: The molecularly imprinted poly(o-phenylenediamine) (PoPD) film was prepared for the analysis of L-ascorbic acid (AA) on gold nanoparticles (AuNPs) - multiwalled carbon nanotubes (MWCNTs) modified glass carbon electrode (GCE) by electropolymerization of o-phenylenediamine (oPD) and AA. Experimental parameters including pH value of running buffer and scan rates were optimized. Scanning electron microscope (SEM), fourier-transform infrared (FTIR) spectra, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were utilized for the characterization of the imprinted polymer film. Results: Under the selected experimental conditions, the DPV peak currents of AA exhibit two distinct linear responses ranging from 0.01 to 2 μmol L-1 and 2 to 100 μmol L-1 towards the concentrations of AA, and the detection limit was 2 nmol L-1 (S/N=3). Conclusion: The proposed electrochemical sensor possesses excellent selectivity for AA, along with good reproducibility and stability. The results obtained from the analysis of AA in real samples demonstrated the applicability of the proposed sensor to practical analysis.

scholarly journals A Label and Probe-Free Zika Virus Immunosensor Prussian Blue@carbon Nanotube-Based for Amperometric Detection of the NS2B Protein

Biosensors ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 157
Author(s):  
Bárbara V. M. Silva ◽  
Marli T. Cordeiro ◽  
Marco A. B. Rodrigues ◽  
Ernesto T. A. Marques ◽  
Rosa F. Dutra
Keyword(s):  
Carbon Nanotube ◽  
Prussian Blue ◽  
Zika Virus ◽  
Point Of Care ◽  
Amperometric Detection ◽  
Cross Reactivity ◽  
Structural Protein ◽  
Serum Samples ◽  
Polypyrrole Composite ◽  
Congenital Disabilities

Zika virus (ZIKV) is a mosquito-borne infection, predominant in tropical and subtropical regions causing international concern due to the ZIKV disease having been associated with congenital disabilities, especially microcephaly and other congenital abnormalities in the fetus and newborns. Development of strategies that minimize the devastating impact by monitoring and preventing ZIKV transmission through sexual intercourse, especially in pregnant women, since no vaccine is yet available for the prevention or treatment, is critically important. ZIKV infection is generally asymptomatic and cross-reactivity with dengue virus (DENV) is a global concern. An innovative screen-printed electrode (SPE) was developed for amperometric detection of the non-structural protein (NS2B) of ZIKV by exploring the intrinsic redox catalytic activity of Prussian blue (PB), incorporated into a carbon nanotube–polypyrrole composite. Thus, this immunosensor has the advantage of electrochemical detection without adding any redox-probe solution (probe-less detection), allowing a point-of-care diagnosis. It was responsive to serum samples of only ZIKV positive patients and non-responsive to negative ZIKV patients, even if the sample was DENV positive, indicating a possible differential diagnosis between them by NS2B. All samples used here were confirmed by CDC protocols, and immunosensor responses were also checked in the supernatant of C6/36 and in Vero cell cultures infected with ZIKV.

scholarly journals Ultrasensitive and label free electrochemical immunosensor for detection of ROR1 as an oncofetal biomarker using gold nanoparticles assisted LDH/rGO nanocomposite

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rozita Abolhasan ◽  
Balal Khalilzadeh ◽  
Hadi Yousefi ◽  
Sahar Samemaleki ◽  
Forough Chakari-Khiavi ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Flexible Structures ◽  
Modified Electrodes ◽  
Electrochemical Immunosensor ◽  
Lymphocytic Leukemia ◽  
Orphan Receptor ◽  
Detection Sensitivity ◽  
Label Free ◽  
Serum Samples ◽  
Limit Of Quantification

AbstractIn the present article, we developed a highly sensitive label-free electrochemical immunosensor based on NiFe-layered double hydroxides (LDH)/reduced graphene oxide (rGO)/gold nanoparticles modified glassy carbon electrode for the determination of receptor tyrosine kinase-like orphan receptor (ROR)-1. In this electrochemical immunoassay platform, NiFe-LDH/rGO was used due to great electron mobility, high specific surface area and flexible structures, while Au nanoparticles were prepared and coated on the modified electrodes to improve the detection sensitivity and ROR1 antibody immobilizing (ROR1Ab). The modification procedure was approved by using cyclic voltammetry and differential pulse voltammetry based on the response of peak current to the step by step modifications. Under optimum conditions, the experimental results showed that the immunosensor revealed a sensitive response to ROR1 in the range of 0.01–1 pg mL−1, and with a lower limit of quantification of 10 attogram/mL (10 ag mL−1). Furthermore, the designed immunosensor was applied for the analysis of ROR1 in several serum samples of chronic lymphocytic leukemia suffering patients with acceptable results, and it also exhibited good selectivity, reproducibility and stability.

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