In this work we developed an immunosensor for HIV-1 diagnostics that exploits the biorecognition between the antibody anti-p24 and the antigenic peptide p24-3 (AMATLRAEQASQEVKNWMTETL- LVQNA) derived ...from the HIV-1 p24 protein. p24-3 was encapsulated in phospholipid liposomes and immobilized in layer-by-layer (LbL) films produced with polyethyleneimine (PEI). The incorporation of p24-3 into liposomes was investigated using circular dichroism (CD) spectroscopy, from which an increase in the alpha helix conformation could be noted. The maximum fluorescence emission for p24-3 occurred at 340 nm in solution, compatible with the tryptophan residue being exposed to the solvent, and at 335 and 322 nm when in liposomes and PEI/p24-3-liposome LbL films, respectively. This blue shift is consistent with the tryptophan being in a partially buried environment. With the preserved structure in the LbL films, p24-3 could recognize the anti-p24 antibody in impedance spectroscopy measurements. Therefore, LbL films containing p24-3 may be suitable for detecting HIV-1 in a low-cost, easy-to-use immunosensing assay.
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High molecular weight Chi modulates the orientation of SF groups (Try and Try).Chi and SF LbL films were successfully used as template for phytase immobilization.The matrix ...improved the performance of phytic acid biosensing.
In this paper, we show that chitosan may induce conformation changes in silk fibroin (SF) in layer-by-layer (LbL) films, which were used as matrix for immobilization of the enzyme phytase to detect phytic acid. Three chitosan (CH) samples possessing distinct molecular weights were used to build CH/SF LbL films, and a larger change in conformation from random coils to β-sheets for SF was observed for high molecular weight chitosan (CHH). The CHH/SF LbL films deposited onto interdigitated gold electrodes were coated with a layer of phytase, with which phytic acid could be detected down to 10⿿9M using impedance spectroscopy as the principle of detection and treating the data with a multidimensional projection technique. This high sensitivity may be ascribed to the suitability of the CHH/SF matrix, thus indicating that the molecular-level interactions between chitosan and SF may be exploited in other biosensors and biodevices.
The development of simple detection methods aimed at widespread screening and testing is crucial for many infections and diseases, including prostate cancer where early diagnosis increases the ...chances of cure considerably. In this paper, we report on genosensors with different detection principles for a prostate cancer specific DNA sequence (PCA3). The genosensors were made with carbon printed electrodes or quartz coated with layer-by-layer (LbL) films containing gold nanoparticles and chondroitin sulfate and a layer of a complementary DNA sequence (PCA3 probe). The highest sensitivity was reached with electrochemical impedance spectroscopy with the detection limit of 83 pM in solutions of PCA3, while the limits of detection were 2000 pM and 900 pM for cyclic voltammetry and UV–vis spectroscopy, respectively. That detection could be performed with an optical method is encouraging, as one may envisage extending it to colorimetric tests. Since the morphology of sensing units is known to be affected in detection experiments, we applied machine learning algorithms to classify scanning electron microscopy images of the genosensors and managed to distinguish those exposed to PCA3-containing solutions from control measurements with an accuracy of 99.9%. The performance in distinguishing each individual PCA3 concentration in a multiclass task was lower, with an accuracy of 88.3%, which means that further developments in image analysis are required for this innovative approach.
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•Low-cost biosensors fabricated with gold nanoparticles and chondroitin sulfate used for detecting PCA3 biomarker.•PCA3 detection from machine learning with accuracy of 99.9%.•The highest sensitivity was reached with electrochemical impedance spectroscopy with the detection limit of 83 pM.
We report the fabrication of immunosensors based on nanostructured mats of electrospun nanofibers of polyamide 6 and poly(allylamine hydrochloride) coated either with multiwalled carbon nanotubes ...(MWCNTs) or gold nanoparticles (AuNPs), whose three-dimensional structure was suitable for the immobilization of anti-CA19-9 antibodies to detect the pancreatic cancer biomarker CA19-9. Using impedance spectroscopy, the sensing platform was able to detect CA19-9 with a detection limit of 1.84 and 1.57 U mL–1 for the nanostructured architectures containing MWCNTs and AuNPs, respectively. The high sensitivity achieved can be attributed to the irreversible adsorption between antibodies and antigens, as confirmed with polarization-modulated infrared reflection absorption spectroscopy. The adsorption mechanism was typical Langmuir–Freundlich processes. The high sensitivity and selectivity of the immunosensors were also explored in tests with blood serum from patients with distinct concentrations of CA19-9, for which the impedance spectra data were processed with a multidimensional projection technique. The robustness of the immunosensors in dealing with patient samples without suffering interference from analytes present in biological fluids is promising for a simple, effective diagnosis of pancreatic cancer at early stages.
Objective:
To evaluate the dependence of age and blood pressure (BP) on the estimated pulse wave velocity (PWV) by Mobil-o-Graph and an equation derived from the Reference Values for Arterial ...Stiffness Collaboration.
Design and method:
This study is a secondary analysis of a database from a cross-sectional study conducted in a specialized center in inner Brazil to diagnose and treat non-communicable diseases. We included individuals with hypertension and at least one risk factor, dyslipidemia, diabetes, smoking, body mass index (BMI) > = 30 kg/m
2
. Three accurate office BP measurements were made and calculated the average (OBP) using Microlife equipment BP3AC1-1PC (Onbo Electronic Co, Shenzhen, China). The average of four measures of office PWV (oPWV) was calculated using Mobil-O-Graph device (I.E.M., Stolberg, Germany). Also, estimated PWV (ePWV) was calculated by utilizing age and the mean arterial pressure of OBP (MBP) from an equation derived by the Reference Values for Arterial Stiffness Collaboration as follows:
ePWV = 9.58748315543126-0.402467539733184*age+4.56020798207263*10-3*age
2
-2.6207705511664*10-5*age
2
*MBP+3.1762450559276*10-3*age*MBP-1.8321025*MBP
Five multilevel regression models were used to determine how much ePWV and PWV depend on age, age
2
, systolic OBP, MBP, and all of them together. Forkman test was used to compare the coefficient of determination (R2).
Results:
Table 1 shows the main clinical characteristics of the sample. Table 2 demonstrates the results for comparing the coefficient of determination for ePWV and oPWV. Age determines 75% of ePWV variance and 85% of oPWV (p = 0.0001), age
2
78% of ePWV and 90% of oPWV (p = 0.0001), SBP 41% of ePWV and 18% of oPWV (p<0.0001), MBP 24% of ePWV and 5% of oPWV (p<0.0001). The model 5 shows that the variables studied together determine better the variance of ePWV (99%) than oPWV (94%).
Conclusions:
Age, age
2
, SBP, and MBP explain almost the overall variance of ePWV and oPWV. However, ePWV is significantly more dependent on BP than oPWV, which is considerably more dependent on age.
Resistant hypertension (RH) is characterized by the use of three or more antihypertensive drugs without reaching the goal of controlling blood pressure (BP). For a definitive diagnosis of RH, it is ...necessary to exclude causes of pseudoresistance, including the white-coat effect, errors in BP measurement, secondary hypertension, therapeutic inertia, and poor adherence to lifestyle changes and pharmacological treatment. Herein, we report the history of a patient with long-standing uncontrolled BP, even when using seven antihypertensive drugs. Causes of secondary hypertension that justified the high BP levels were investigated, in addition to the other causes of pseudo-RH. In view of the difficult-to-control BP situation, it was decided to hospitalize the patient for better investigation. After 5 days, he had BP control with practically the same medications previously used. Finally, all factors related to the presence of pseudo-RH are discussed, especially poor adherence to treatment. Poor adherence to antihypertensive treatment is common in daily medical practice, and its investigation is of fundamental importance for better management of BP.
Clinical and experimental data indicate that severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection is associated with significant changes in the composition and function of intestinal ...microbiota. However, the relevance of these effects for SARS-CoV-2 pathophysiology is unknown. In this study, we analyzed the impact of microbiota depletion after antibiotic treatment on the clinical and immunological responses of K18-hACE2 mice to SARS-CoV-2 infection. Mice were treated with a combination of antibiotics (kanamycin, gentamicin, metronidazole, vancomycin, and colistin, Abx) for 3 days, and 24 h later, they were infected with SARS-CoV-2 B lineage. Here, we show that more than 80% of mice succumbed to infection by day 11 post-infection. Treatment with Abx had no impact on mortality. However, Abx-treated mice presented better clinical symptoms, with similar weight loss between infected–treated and non-treated groups. We observed no differences in lung and colon histopathological scores or lung, colon, heart, brain and kidney viral load between groups on day 5 of infection. Despite some minor differences in the expression of antiviral and inflammatory markers in the lungs and colon, no robust change was observed in Abx-treated mice. Together, these findings indicate that microbiota depletion has no impact on SARS-CoV-2 infection in mice.
Detection of human papillomavirus 16 (HPV16) is essential for the diagnosis of cervix and head and neck cancer, which has prompted the development of biosensors to replace the sophisticated molecular ...techniques. In this paper, we employ a genosensor made with a HPV16 DNA probe (cpHPV16) immobilized on a layer-by-layer (LbL) film of chitosan and carbon nanotubes to detect a complementary sequence HPV16 oligo (ssHPV16). In addition to employing impedance spectroscopy, which has already been used in the literature, we detect ssHPV16 in buffer samples and in cancer cell line samples with UV-vis. spectroscopy. The limit of detection was 18.5 pmol L
−1
in impedance spectroscopy measurements and 10.9 pmol L
−1
in UV-vis measurements. Distinction of the various ssHPV16 concentrations and of the cancer cell line samples CasKi, SiHa, UMSCC-47, UM-SCC104 and 93-VU147T with both electrical and optical data could be made with the multidimensional projection technique referred to as interactive document mapping (IDMAP), with which we could confirm the absence of false positives by testing cell lines that did not contain ssHPV16 (JHU12, JHU13 and JHU28). The hybridization between cpHPV16 and ssHPV16 responsible for the biosensing was verified with polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), while the concentration dependence could be modeled with a double Freundlich function. The use of optical absorbance measurements to detect ssHPV16 is promising toward a simple colorimetric detection.
Electrode modified with chitosan, carbon nanotubes and a layer of cpHPV16 DNA probe to which ssHPV16 DNA binds.
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