scholarly journals Reagentless Biomolecular Analysis Using a Nanoscale Molecular Pendulum

2020 ◽  
Author(s):  
Jagotamoy Das ◽  
Surath Gomis ◽  
Jenise B. Chen ◽  
Hanie Yousefi ◽  
Sharif Ahmed ◽  
...  
Keyword(s):  
Cardiovascular Health ◽  
Biological Fluids ◽  
Unmet Need ◽  
Molecular Size ◽  
Electron Transfer Reaction ◽  
Time Resolved ◽  
Sensing Mechanism ◽  
Directional Diffusion ◽  
Diffusional Motion ◽  
Physiological Markers

AbstractThe ability to sense biological inputs using self-contained devices unreliant on external reagents or reporters would open countless opportunities to collect information about our health and environment. Currently, a very limited set of molecular inputs can be detected using this type of sensor format. The development of versatile reagentless sensors that could track molecular analytes in biological fluids remains an unmet need. Here, we describe a new universal sensing mechanism that is compatible with the analysis of proteins that are important physiological markers of stress, allergy, cardiovascular health, inflammation and cancer. The sensing mechanism we developed is based on the measurement of field-induced directional diffusion of a nanoscale molecular pendulum tethered to an electrode surface and the sensitivity of electron-transfer reaction kinetics to molecular size. Using time-resolved electrochemical measurements of diffusional motion, the presence of an analyte bound to a sensor complex can be continuously tracked in real time. We show that this sensing approach is compatible with making measurements in blood, saliva, urine, tears and sweat and that the sensors can collect data in situ in living animals. The sensor platform described enables a broad range of applications in personalized health monitoring.

Time-resolved immunofluorometric assay of complement C3: application to cerebrospinal fluid

1993 ◽  
Vol 39 (2) ◽  
pp. 309-312 ◽  
Author(s):  
O Gaillard ◽  
D Meillet ◽  
M C Diemert ◽  
L Musset ◽  
J Delattre ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Neurological Disorders ◽  
Biological Fluids ◽  
Clinical Applications ◽  
Complement C3 ◽  
Complement Components ◽  
Time Resolved ◽  
Sandwich Type ◽  
Analytical Range ◽  
Immunochemical Methods

Abstract Complement components have a role in various neurological disorders. Complement C3 can be measured by immunochemical methods, but only radioimmunoassays and electroimmunodiffusion assays (EIDs) are sufficiently sensitive to be applied to biological fluids in which the C3 concentration is low, especially cerebrospinal fluid (CSF). We report a sandwich-type time-resolved immunofluorometric assay (TR-IFMA) for C3 in CSF. The linearity (0.7-3650 micrograms/L) and intra- (CV < 4.8%) and inter-assay (CV < 10.9%) precision were satisfactory and the results agreed with those of EID. The assay is extremely sensitive (< 1 microgram/L) and its analytical range is large and well suited to clinical applications. This simple TR-IFMA is thus a nonisotopic alternative to radioimmunoassay for the quantification of complement C3 in CSF.

Electrochemistry of Alzheimer Disease Amyloid Beta Peptides

2018 ◽  
Vol 25 (33) ◽  
pp. 4066-4083 ◽  
Author(s):  
Ana-Maria Chiorcea-Paquim ◽  
Teodor Adrian Enache ◽  
Ana Maria Oliveira-Brett
Keyword(s):  
Amino Acid ◽  
Amyloid Beta ◽  
Biological Fluids ◽  
Electron Transfer Reaction ◽  
Random Coil ◽  
Sequence Length ◽  
Dependent Manner ◽  
Aβ Peptide ◽  
Aβ Peptides ◽  
Α Helix

Alzheimer’s disease (AD) is a widespread form of dementia that is estimated to affect 44.4 million people worldwide. AD pathology is closely related to the accumulation of amyloid beta (Aβ) peptides in fibrils and plagues, the small oligomeric intermediate species formed during the Aβ peptides aggregation presenting the highest neurotoxicity. This review discusses the recent advances on the Aβ peptides electrochemical characterization. The Aβ peptides oxidation at a glassy carbon electrode occurs in one or two steps, depending on the amino acid sequence, length and content. The first electron transfer reaction corresponds to the tyrosine Tyr10 amino acid residue oxidation, and the second to all three histidine (His6, His13 and His14) and one methionine (Met35) amino acid residues. The Aβ peptides aggregation and amyloid fibril formation are electrochemically detected via the electroactive amino acids oxidation peak currents decrease that occurs in a time dependent manner. The Aβ peptides redox behaviour is correlated with changes in the adsorption morphology from initially random coiled structures, corresponding to the Aβ peptide monomers in random coil or in α-helix conformations, to aggregates, protofibrils and two types of fibrils, corresponding to the Aβ peptides in a β-sheet configuration, observed by atomic force microscopy. Electrochemical studies of Aβ peptides aggregation, mediated by the interaction with metal ions, particularly zinc, copper and iron, and different methodologies concerning the detection of Aβ peptide biomarkers of AD in biological fluids, using electrochemical biosensors, are also discussed.

Molecular Size Distribution of Fibrinogen Derivatives Formed in Vitro and in Vivo: a Chromatographic Study

1976 ◽  
Vol 36 (01) ◽  
pp. 014-026 ◽  
Author(s):  
M. B Donati ◽  
R Verhaeghe ◽  
D. E Culasso ◽  
J Vermylen
Keyword(s):  
Biological Fluids ◽  
Gel Filtration ◽  
Molecular Size ◽  
Gel Chromatography ◽  
Chromatographic Study ◽  
Elution Volume ◽  
Human Fibrinogen ◽  
Elution Pattern

SummaryUsing gel chromatography, fibrinogen derivatives present in purified systems or in biological fluids were separated and partially characterized. Eight groups of fibrinogen derivatives could be separated by gel filtration through 6% agarose in large columns, four with an elution volume smaller and four groups with an elution volume larger than that of fibrinogen. Careful calibration of the column allowed estimation of the diffusion coefficients of some of the derivatives and, thus, comparison with derivatives previously identified. Three, rather than two, groups of intermediate derivatives were observed during the degradation of human fibrinogen by plasmin in vitro or in vivo. One of these had a marked tendency to polymerize.A rather distinct difference in elution pattern was found between plasma obtained during streptokinase administration and from patients with intravascular coagulation.

Development of Time-Resolved Immunofluorometric Assay of Vascular Permeability Factor

1992 ◽  
Vol 38 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Kiang-Teck Yeo ◽  
Tracy M Sioussat ◽  
James D Faix ◽  
Donald R Senger ◽  
Tet-Kin Yeo
Keyword(s):  
Vascular Permeability ◽  
Culture Medium ◽  
Biological Fluids ◽  
Analytical Sensitivity ◽  
Vascular Permeability Factor ◽  
Time Resolved ◽  
Permeability Factor ◽  
Pre Treatment ◽  
Highly Correlated ◽  
Permeability Assay

Abstract We describe a two-site time-resolved immunofluorometric assay for guinea pig vascular permeability factor (VPF) for quantifying VPF in different biological fluids. Antibody against the carboxy terminus (C-IgG) is immobilized on microtiter wells, and antibody against the amino terminus (N-IgG) is labeled with Eu(3+)-chelate. Line 10 tumor culture medium, known to be rich in VPF, is assayed in a two-step incubation. Bound Eu3+ is then quantified by dissociation into a fluorescent enhancement solution, with measurement of the time-resolved fluorescence. The analytical sensitivity is 0.35 VPF unit, and the intra-assay CV is about 20%. The assay is specific for VPF, because pre-treatment with the appropriate C- or N-peptide, or pre-extraction of VPF, greatly decreases fluorescence. The VPF immunoassay is highly correlated (r2 = 0.94) with the Miles permeability assay, the classical bioassay of VPF. In addition, the immunofluorometric assay is about 30-fold more sensitive than the Miles assay.

Development of Various Types and Forms of Messages for Smartphone-Based Cardiac Rehabilitation for Secondary Prevention in Patients with Coronary Artery Disease (Preprint)

2020 ◽  
Author(s):  
Eung Ju Kim ◽  
Jah Yeon Choi ◽  
Ji Bak Kim ◽  
Sunki Lee ◽  
Seo-Joon Lee ◽  
...  
Keyword(s):  
Smoking Cessation ◽  
Secondary Prevention ◽  
Cardiac Rehabilitation ◽  
Transtheoretical Model ◽  
Clinical Benefit ◽  
Cardiovascular Health ◽  
Unmet Need ◽  
Smartphone Application ◽  
General Information ◽  
Patient Specific

BACKGROUND Despite strong evidence of clinical benefit, cardiac rehabilitation (CR) programs are currently underutilized and smartphone-based CR strategies are thought to address this unmet need. However, the previous applications have several limitations and there are scarce data regarding its usefulness and clinical benefit. The application for self-improvement (AnSim) trial is a multicenter, prospective randomized trial to explore the feasibility and efficacy of smartphone-based messaging application for patients who underwent percutaneous coronary intervention (PCI). OBJECTIVE The current study will focus on the development of a smartphone-based, patient-specific messaging application and detailed design of the trial. METHODS The AnSim application is developed by multidisciplinary team collaboration including cardiologists, psychiatrists, nurses, pharmacists, nutritionists, and rehabilitation doctor and therapists. First, the focus group interview was conducted and narratives of the patients were analyzed to identify their needs and preferences. Based on the results, health care experts and clinicians drafted messages into 5 categories: (1) general information regarding cardiovascular health and medications, (2) nutrition, (3) physical activity, (4) destressing, and (5) smoking cessation. In each category, 30 messages were developed according to three simplified steps of the transtheoretical model of behavioral change: (1) pre-contemplation, (2) contemplation and preparation, and (3) action and maintenance. After internal review and feedback from potential users, a bank of 450 messages and application were finally developed. RESULTS The focus interview was performed with 8 patients with recent PCI within 1 month and development of 450 messages were done. Positive feedback obtained from the potential users (n = 200) that Likert scale score was 3.95±SD and 3.91±SD for readability and usefulness, respectively. Based on the results, the several messages were refined. Furthermore, messages using various forms of multimedia such as exercise videos and dietary regimens, and connection for smoking cessation center were also developed as needed. CONCLUSIONS A final bank of 450 smartphone-based, patient-specific messages were developed to support behavior change and decrease cardiovascular risk factors through 5 step iterative process. The detailed process of multidisciplinary collaboration in the course of the study provides a scientific basis for various medical professionals who are planning smartphone based clinical research and AnSim trial will demonstrate the feasibility and efficacy of a patient-specific messaging smartphone application in secondary prevention of coronary heart disease.

Roaming as the dominant mechanism for molecular products in the photodissociation of large aliphatic aldehydes

2015 ◽  
Vol 17 (35) ◽  
pp. 23112-23120 ◽  
Author(s):  
Po-Yu Tsai ◽  
Hou-Kuan Li ◽  
Toshio Kasai ◽  
King-Chuen Lin
Keyword(s):  
Fourier Transform ◽  
Emission Spectroscopy ◽  
Molecular Size ◽  
Fourier Transform Infrared ◽  
Infrared Emission ◽  
Aliphatic Aldehydes ◽  
Time Resolved ◽  
Dominant Mechanism ◽  
Infrared Emission Spectroscopy

Photodissociation of isobutyraldehyde (C3H7CHO) at 248 nm is investigated using time-resolved Fourier-transform infrared emission spectroscopy to demonstrate the growing importance of the roaming pathway with increasing molecular size of aliphatic aldehydes.

Direct homogeneous phosphoroimmunoassay for carbamazepine in serum.

1986 ◽  
Vol 32 (1) ◽  
pp. 53-56 ◽  
Author(s):  
A M Sidki ◽  
D S Smith ◽  
J Landon
Keyword(s):  
Room Temperature ◽  
Biological Fluids ◽  
Liquid Solution ◽  
Oxygen Quenching ◽  
Time Resolved ◽  
Excited Triplet ◽  
Complete Rejection ◽  
Pre Treatment ◽  
Development And Validation

Abstract In this "phosphoroimmunoassay," a phosphorescent label is used: erythrosin (tetraiodofluorescein). Its long-lived phosphorescence was detected after pulsed excitation in a time-resolved luminescence spectrometer. To achieve convenient open-atmosphere phosphorimetry in liquid solution at room temperature, we used sodium sulfite as an "in situ" chemical deoxygenator, to eliminate oxygen quenching of the excited triplet state. Time-resolved detection allows for complete rejection of short-lived background signals, including those from fluorescent or light-scattering components of biological fluids that can interfere in fluoroimmunoassays. We chose the antiepileptic drug carbamazepine (CBZ) and its active metabolite CBZ-10, 11-epoxide (CBZE) to demonstrate the development and validation of nonseparation assays based on quenching the phosphorescence of erythrosin-labeled drug upon binding to antibody. These two compounds cross reacted equally with the antiserum used; hence, we measured the activity of both in patients' sera. Alternatively, simple pre-treatment of the sample with acid destroys CBZE immunoreactivity and enables specific assay of CBZ.

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