Elucidating the mechanism of dual-fluorescence in carbon dots

Carbon dots have garnered significant attention owing to their versatile and highly tunable optical properties; however, the origins and the underlying mechanism remains a subject of debate especially for dual fluorescent systems. Here, we have prepared carbon dots from glutathione and formamide precursors via a one-pot solvothermal synthesis. Steady state and dynamic techniques indicate that these dual fluorescent dots possess distinct emissive carbon-core and a molecular states, which are responsible for the blue and red optical signatures, respectively. To further glean information into the fluorescence mechanism, electrochemical analysis was used to measure the bandgaps of the two fluorescent states, while femtosecond transient absorption spectroscopy evidenced the two-state model based on the observed heterogeneity and bimodal spectral distribution. Our findings provide novel and fundamental insights on the optical properties of dual fluorescent dots, which can translate to more effective and targeted application development particularly in bioimaging, multiplexed sensing and photocatalysis

Time course of the development of cytopathic effects by Lone Star virus in human (HeLa) and monkey (Vero) cell cultures.

<p>CPE is shown at 24, 48, 72, 96, and 120 hours post-inoculation (hpi). Uninfected controls at 120 hpi are also shown.</p

Amino acid pairwise identity of LSV relative to other representative bunyaviruses.

<p>The amino acid identities are shown for the four LSV proteins (RdRp, G, N, and NSs). A sliding window of 50 bp was used. GenBank accession numbers are reported in the text.</p

Deep sequencing reads matching to viral sequences.

*<p>Viral reads were identified by comparison to viral nucleotide and amino acid databases using the SNAP <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062083#pone.0062083-Zaharia1" target="_blank">[29]</a> and RAPSearch <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062083#pone.0062083-Ye1" target="_blank">[30]</a> aligners, respectively. Viral hits were confirmed to be true by BLASTn alignment to LSV or the closest viral genus or species in GenBank using an E-value cutoff of 1×10⁻⁸. Out of 15,134,328 total reads, 40,489 reads (0.27%) were identified as viral by SNAP and/or RAPSearch. Out of these 40,489 viral hits, 37,322 (92.2%) corresponded to LSV. The actual number of LSV reads in the dataset is 142,941 (0.94% of the total reads); thus, only 26.1% (37,322 of 142,941) of the actual number of LSV reads was detected.</p

Amino acid phylogenetic analysis of the four LSV protein sequences relative to those from representative phleboviruses and Gouleako virus.

<p>For the RdRp, glycoprotein, and N protein, Gouleako virus is included as an outgroup to the phleboviruses (tan). Gouleako virus, the closest known bunyavirus relative to phleboviruses, is a member of a proposed new genus in the family <i>Bunyaviridae </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062083#pone.0062083-Marklewitz1" target="_blank">[36]</a>. Also shown color-coded are the Uukuniemi (blue), Bhanja (red), and SFTS (green) clades of known tick-borne phleboviruses. GenBank accession numbers are reported in the text.</p

Identification and assembly of the LSV genome by unbiased deep sequencing.

<p>(<b>A</b>) Using a rapid computational pipeline, reads identified as bunyaviruses by SNAP nucleotide alignment (orange) or RAPSearch amino acid alignment (dark red) were mapped to the assembled LSV genome. The coverage (y-axis) achieved at each position along the genome (x-axis) is plotted on a logarithmic scale. (<b>B</b>) <i>De novo</i> assembly of the LSV genome using the PRICE assembler (3 rounds of 15 cycles each) and LSV seed sequences (“S”) identified from (A). (<b>C</b>) The genome structure of LSV. Boxes represent open reading frames (ORFs) corresponding to the RdRp, G, N, and NSs proteins, flanked by noncoding regions, which are indicated by lines. Coding directions are indicated by arrows. (<b>D</b>) Mapping of the actual deep sequencing reads derived from LSV to the final assembled genome. The coverage (y-axis) achieved at each position along the genome (x-axis) is plotted on a logarithmic scale. GenBank accession numbers are reported in the text. Abbreviations: kb, kilobases; bp, base pairs.</p