We report the chemical synthesis and derivatization of an ortho‐functionalized tetrachlorinated azobenzene diol. A 4′,4‐dimethoxytrityl (DMT) phosphoramidite was synthesized for its site‐specific incorporation within the sense strand of an siRNA duplex to form ortho‐functionalized tetrachlorinated azobenzene‐containing siRNAs (Cl‐siRNAzos). Compared to a non‐halogenated azobenzene, ortho‐functionalized tetrachlorinated azobenzenes are capable of red‐shifting the π→π* transition from the ultraviolet (UV) portion of the electromagnetic spectrum into the visible range. Within this visible range, the azobenzene molecule can be reliably converted from trans to cis with red light (660 nm), and converted back to trans with violet wavelength light (410 nm) and/or thermal relaxation. We also report the gene‐silencing ability of these Cl‐siRNAzos in cell culture as well as their reversible control with visible light for up to 24 hours.
One of the major hurdles in RNAi research has been the development of safe and effective delivery systems for siRNAs. Although various chemical modifications have been proposed to improve their pharmacokinetic behaviour, their delivery to target cells and tissues presents many challenges. In this work, we implemented a receptor-targeting strategy to selectively deliver siRNAs to cancer cells using folic acid as a ligand. Folic acid is capable of binding to cell-surface folate receptors with high affinity. These receptors have become important molecular targets for cancer research as they are overexpressed in numerous cancers despite being expressed at low levels in normal tissues. Employing a post-column copper-catalyzed alkyne–azide cycloaddition (CuAAC), we report the synthesis of siRNAs bearing folic acid modifications at different positions within the sense strand. In the absence of a transfection carrier, these siRNAs were selectively taken up by cancer cells expressing folate receptors. We show that centrally modified folic acid–siRNAs display enhanced gene-silencing activity against an exogenous gene target (∼80% knockdown after 0.75 μM treatment) and low cytotoxicity. In addition, these siRNAs achieved potent dose-dependent knockdown of endogenous Bcl-2, an important anti-apoptotic gene.
The recent COVID-19 pandemic overwhelmed the health system worldwide, and there was a
need to track outbreaks and try to use this information as an early warning system.
Wastewater-based epidemiology (WBE) enabled detection of the SARS-CoV-2 virus in
wastewater treatment plant influents. Until now, the most used technique for this
detection has been the quantitative polymerase chain reaction (qPCR)-based
quantification of SARS-CoV-2 RNA. This study proposes a mass spectrometry (MS)-based
method that detected specific SARS-CoV-2 proteins in wastewater, 5 and 6 days ahead of
the case data for two municipalities. We identified unique peptides of eight proteins
related to the SARS-CoV-2 virus and COVID-19 infection. We detected the nonstructural
protein (NSP) pp1ab (transcribed after host cell infection) most frequently in all of
the samples. As a result, we suspect that in the active cases of COVID-19, the pp1ab
protein is present in high abundance in the urine and feces and that this protein could
be used as an alternative biomarker. These data were collected before mass vaccination
occurred in the population.
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