Direct Mapping of Heterogeneous Surface Coverage in DNA-Functionalized Gold Surfaces with Correlated Electron and Fluorescence Microscopy

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) -induced infection, the cause of coronavirus disease 2019 (COVID-19), is characterized by unprecedented clinical pathologies. One of the most important pathologies, is hypercoagulation and microclots in the lungs of patients. Here we study the effect of isolated SARS-CoV-2 spike protein S1 subunit as potential inflammagen sui generis. Using scanning electron and fluorescence microscopy as well as mass spectrometry, we investigate the potential of this inflammagen to interact with platelets and fibrin(ogen) directly to cause blood hypercoagulation. Using platelet poor plasma (PPP), we show that spike protein may interfere with blood flow. Mass spectrometry also showed that when spike protein S1 is added to healthy PPP, it results in structural changes to β and γ fibrin(ogen), complement 3, and prothrombin. These proteins were substantially resistant to trypsinization, in the presence of spike protein S1. Here we suggest that, in part, the presence of spike protein in circulation may contribute to the hypercoagulation in COVID-19 positive patients and may cause substantial impairment of fibrinolysis. Such lytic impairment may result in the persistent large microclots we have noted here and previously in plasma samples of COVID-19 patients. This observation may have important clinical relevance in the treatment of hypercoagulability in COVID-19 patients.

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Dyskinetoplasty in two species of trypanosomatids

Journal of Cell Science ◽

10.1242/jcs.35.1.185 ◽

1979 ◽

Vol 35 (1) ◽

pp. 185-202

Author(s):

S.L. Hajduk

Keyword(s):

Fluorescence Microscopy ◽

Kinetoplast Dna ◽

Feulgen Staining ◽

Crithidia Fasciculata ◽

Caesium Chloride ◽

Electron And Fluorescence Microscopy ◽

Staining Techniques ◽

Trypanosoma Equiperdum ◽

In Cells

Dyskinetoplastic cells from both Crithidia fasciculata and Trypanosoma equiperdum lack detectable kinetoplast DNA (kDNA) by conventional staining techniques. Two dyskinetoplastic strains of T. equiperdum, either acriflavine-induced or spontaneously occurring, show normal amounts of kDNA (p = 1.692 g/cm3) in analytical caesium chloride, ultracentrifugation. Electron and fluorescence microscopy of the dyskinetoplastic strains of T. equiperdum suggest that the kDNA network is fragmented and dispersed throughout the mitochondrion. The fragmentation and dispersion of the kDNA, rather than a reduction in the amount of kDNA, is the cause of the lack of kinetoplast staining in the dyskinetoplastic strains of T. equiperdum. Acriflavine-treated cultures of C. fasciculata show a decrease in the amount of kDNA (p = 1.703 g/cm3) corresponding to the percentage of dyskinetoplastic cells in the cultures. Electron and fluorescence microscopy of acriflavine-treated cultures of C. fasciculata show the loss of the kDNA network in cells which lack Giemsa and Feulgen staining, confirming the hypothesis that the kDNA is lost in dyskinetoplastic trypanosomatids from insects. Possible modes of acriflavine action are considered and a proposed mechanism for acriflavine action in trypanosomes from mammals is presented.

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Legumain Targeting Peptide Conjugated Fluorescent Porous Silicon Nanoparticles for Breast Cancer Imaging

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.102.45 ◽

2016 ◽

Vol 102 ◽

pp. 45-50 ◽

Cited By ~ 1

Author(s):

Jayasree S. Kanathasan ◽

Varghese Swamy ◽

Uma Devi Palanisamy ◽

Ammu Kutty G.K. Radhakrishnan

Keyword(s):

Porous Silicon ◽

Fluorescence Microscopy ◽

Surface Functionalization ◽

Silicon Nanoparticles ◽

Linear Chain ◽

Breast Cancer Imaging ◽

Microscopy Imaging ◽

Fluorescence Response ◽

Electron And Fluorescence Microscopy ◽

Targeting Peptide

Porous silicon (PSi) with a suite of most desirable biomaterial properties has attracted great attention as a multifunctional nanoplatform for bioimaging and drug delivery. Various surface functionalization treatments have been reported for PSi to use as an active tumor cell targeting nanovector. In this study, we investigated surface functionalization treatments using a peptide that is specific to the emerging biomarker legumain. The PSi nanoparticles were coated with dextran and subsequently two types of legumain targeting peptide, Y-shaped and linear chain, were conjugated to produce the functionalized PSi. The functionalized (ligand-conjugated) PSi materials were characterized for morphology, size, functional groups, and fluorescence response using electron and fluorescence microscopy and vibrational spectroscopy techniques. Fluorescence microscopy imaging with two excitation wavelengths (450 nm and 600 nm) suggests comparable fluorescence response of the conjugated PSi to “bare” PSi and the suitability of the PSi functionalized with peptide for bioimaging.

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