The global pandemic caused by the severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2) virus has revealed the urgent need for accurate, rapid, and affordable
diagnostic tests for epidemic understanding and management by monitoring the population
worldwide. Though current diagnostic methods including real-time polymerase chain
reaction (RT-PCR) provide sensitive detection of SARS-CoV-2, they require relatively
long processing time, equipped laboratory facilities, and highly skilled personnel.
Laser-scribed graphene (LSG)-based biosensing platforms have gained enormous attention
as miniaturized electrochemical systems, holding an enormous potential as point-of-care
(POC) diagnostic tools. We describe here a miniaturized LSG-based electrochemical
sensing scheme for coronavirus disease 2019 (COVID-19) diagnosis combined with
three-dimensional (3D) gold nanostructures. This electrode was modified with the
SARS-CoV-2 spike protein antibody following the proper surface modifications proved by
X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM)
characterizations as well as electrochemical techniques. The system was integrated into
a handheld POC detection system operated using a custom smartphone application,
providing a user-friendly diagnostic platform due to its ease of operation,
accessibility, and systematic data management. The analytical features of the
electrochemical immunoassay were evaluated using the standard solution of S-protein in
the range of 5.0–500 ng/mL with a detection limit of 2.9 ng/mL. A clinical study
was carried out on 23 patient blood serum samples with successful COVID-19 diagnosis,
compared to the commercial RT-PCR, antibody blood test, and enzyme-linked immunosorbent
assay (ELISA) IgG and IgA test results. Our test provides faster results compared to
commercial diagnostic tools and offers a promising alternative solution for
next-generation POC applications.
Electrical wiring of different types of pyranose oxidase (P2O) (fungal wild type, recombinant wild type with a hexahistidine tag, mutant form E542K with a hexa-histidine tag) from Trametes multicolor, and recombinant P2O from Coriolus sp. overexpressed in Escherichia coli as well as of pyranose dehydrogenase (PDH) from Agaricus meleagris and Agaricus xanthoderma with an osmium redox polymer (poly(1-vinylimidazole) 12 -[Os(4,4'-dimethyl-2,2'-dipyridyl) 2 -Cl 2 ] 2þ/þ ) on graphite electrodes was carried out. After optimization studies using glucose as substrate, the biosensors, which showed the best characteristics in terms of linear range, detection limit and sensitivity were selected, viz. wild type P2O from T. multicolor and PDH from A. meleagris. These two enzymes were used and investigated for their selectivity for a number of different sugars.
Diabetes mellitus is one of the most prevalant diseases of adults. Agents with alpha-glucosidase inhibitory activity have been useful as oral hypoglycemic drugs for the control of hyperglycemia in patients with type 2; noninsulin-dependent, diabetes mellitus (NIDDM). Investigation of some medicinal herbs: Urtica dioica, Taraxacum officinale, Viscum album, and Myrtus communis with alpha-glucosidase inhibitor activity was conducted to identify a prophylactic effect for diabetes in vitro. All plants showed differing potent alpha-glucosidase inhibitory activity. However, Myrtus communis strongly inhibited the enzyme (IC50 = 38 microg/mL). The inhibitory effect of these plants and some common antidiabetic drugs against the enzyme source (baker's yeast, rabbit liver, and small intestine) were also searched. Approximately all inhibitors used in this study showed quite different inhibitory activities, according to alpha-glucosidase origins. Furthermore, subsequent separation of the active material from Myrtus communis by HPLC showed that only one fraction acted as an a-glucosidase inhibitor.
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