Rapid and low-cost diagnosis of COVID-19 is essential to identify the infected subjects, particularly the asymptomatic cases, primarily to arrest the spread of the disease through local transmission. Antibody-based chromatographic serological tests, as an alternative to RT-PCR, offer only limited help due to high false positives. We propose to exploit our field-deployable/ portable plasmonic fiber-optic absorbance biosensor (P-FAB) platform for one-step, wash-free detection of SARS-CoV-2 virus particles directly in saliva sample with minimal sample pre-processing.

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IntroductionThe human ␤-and ␣-globin gene loci are developmentally regulated and are arrayed spatially in the order in which they are expressed developmentally, respectively, 5Ј-⑀-G ␥-A ␥-␤-3Ј and 5Ј--␣-␣-3Ј. Fetal hemoglobin (HbF), an ␣ 2 ␥ 2 -tetramer, predominates from week 8 of gestation through birth, after which it is gradually superseded by adult hemoglobin (HbA), an ␣ 2 ␤ 2 -tetramer. HbF is detectable, at approximately 1%, during adult life. The molecular mechanisms underlying the ␥-to ␤-globin switch during development are not fully understood, but are of compelling interest because a persistence of HbF in adults, whether genetic or pharmacologic in origin, is ameliorative in adult ␤-globin gene disorders such as sickle cell anemia or ␤-thalassemia. 1,2 Intermediaries of mammalian metabolism, such as the shortchain fatty acids (SCFAs) butyrate and propionate, are important fuels during fetal life and, when elevated, are implicated in the delayed fetal-to-adult hemoglobin switch in infants of diabetic mothers (butyrate 3 ) and in the elevated HbF levels seen in children with inherited disorders of branched-chain amino acid metabolism (eg, propionic acidemia 4 or ␤-ketothiolase deficiency 5 ). Importantly, therapeutic trials of butyrate in patients with ␤-globin gene disorders have increased ␥-globin gene expression and HbF levels. [6][7][8] Studies of the molecular and cellular effects of SCFAs in erythroid cells have been constrained by the limited number of experimental models currently available. We were interested in finding additional models in which to study the effects of SCFAs on erythropoiesis and on erythroid gene expression. We evaluated the effects of SCFAs on murine erythropoeisis in primitive and definitive erythroid precursor cells from transgenic mice that had endogenous elevations of SCFAs, and in definitive erythroid precursor cells from wt mice and human ␤-globin gene locuscontaining transgenic mice. These studies were undertaken with the expectation that a biologically relevant, primary, definitive erythroid precursor cell model would be an excellent place in which to study the pleiotropic effects of SCFAs on erythropoiesis.The murine ␤-globin gene locus, like the human, is developmentally regulated. ␤ H1 expression is detectable early and persists through embryonic day (E) 12 to 13, while ⑀ y expression is detected later and is present through E13 through 16. 9,10 These embryonic ␤-type globin genes, and the embryonic ␣-like -globin gene, are expressed in large, slowly enucleating, primitive erythroid (EryP) cells from the murine yolk sac. Adult ␤-type globin genes, ␤ Adult , comprise the ␤ maj and ␤ min genes (from the ␤-diffuse haplotype found in most strains) or the ␤ S and ␤ T genes (from the ␤-single haplotype found in the C57/black 6 strain). ␤ Adult and ␣ are expressed primarily in small, rapidly enucleated, definitive erythroid (EryD) cells that arise from the erythroid fetal liver through late gestation and from the adult bone marrow and, in anemic animals, from the adult e...

SARS-CoV-2 nucleocapsid protein-based COVID-19 diagnosis is a promising alternative to the highpriced, time-consuming, and labor-intensive RT-PCR tests.Here, we developed a rapid, dip-type, wash-free plasmonic fiber optic absorbance biosensor (P-FAB) strategy for the point-of-care detection of SARS-CoV-2 N-protein, expressed abundantly during the infection. P-FAB involves a sandwich assay with plasmonic labels on the surface of a U-bent fiber optic sensor probe with a high evanescent wave absorbance (EWA) sensitivity. The SARS-CoV-2 N-protein is quantified in terms of the change in the intensity of the light propagating through the U-bent sensor probe coupled to a green LED and a photodetector. Firstly, the optical fiber material (silica vs. polymeric optical fiber), was evaluated to realize a sensitive sensor platform. The optimal size of AuNP labels (20, 40, and 60 nm) to achieve high sensitivity and a lower limit of detection (LoD) was investigated. Following the P-FAB strategy, fused silica/glass optical fiber (GOF) U-bent senor probe and citrate-capped AuNP labels (size ∼40 nm) gave rise to an LoD down to ∼2.5 ng/mL within 10 mins of read-out time. Further, studies on development and validation of a point of care (PoC) read-out device, and preclinical studies are in progress.

Pluripotent embryonic stem (ES) cells derived from mammalian blastocyst and the adult fibroblast derived induced pluripotent stem (iPS cells) exhibit complete potential to form cells representing all the primary germ layers such as mesoderm, endoderm and ectoderm. These cells are usually co-cultured with mouse embryonic fibroblast feeders to prevent spontaneous differentiation. Feeder free cultures can provide substantial advantage to improve the efficiency and consistency of the culture conditions. In these studies, we demonstrate that a small dietary compound retinol, the alcohol form of vitamin A has capacity to regulate the pluripotency of pluripotent stem cells and maintain highly enriched population of pluripotent ES and iPS cells in feeder free suspension cultures. Retinol maintains long-term cultures of undifferentiated cells via elevated expression of stem cell specific transcription factors Nanog and Oct4. The studies provide evidence that retinol regulates the self-renewal of pluripotent stem cells via the over expression of insulin like growth factor II (IGFII) that engages PI3 kinase signaling pathway via IGF1 receptor tyrosine kinase. The ES cells retain capacity to generate high degree germline competent chimeric animals after microinjection into blastocysts. The studies offer a convenient system for long term maintenance of pluripotent stem cells via the activation of intracellular machinery for self-renewal by a physiologically relevant compound for large-scale production of high quality pluripotent stem cells.