The lack of blood–brain
barrier (BBB) penetrating ability
has hindered the delivery of many therapeutic agents for tauopathy
treatment. In this study, we report the synthesis of a circular bifunctional
aptamer to enhance the in vivo BBB penetration for better tauopathy
therapy. The circular aptamer consists of one reported transferrin
receptor (TfR) aptamer to facilitate TfR-aptamer recognition-induced
transcytosis across BBB endothelial cells, and one Tau protein aptamer
that we recently selected to inhibit Tau phosphorylation and other
tauopathy-related pathological events in the brain. This novel circular
Tau–TfR bifunctional aptamer displays significantly improved
plasma stability and brain exposure, as well as the ability to disrupt
tauopathy and improve traumatic brain injury (TBI)-induced cognitive/memory
deficits in vivo, providing important proof-of-principle evidence
that circular Tau–TfR aptamer can be further developed into
diagnostic and therapeutic candidates for tauopathies.
A simple and rapid method for detection of potassium ion (K(+)) based on a guanine chemiluminescence (CL) system is presented. In this system, one guanine-rich DNA molecule is used as the recognition element. K(+) can cause the guanine-rich DNA to form a G-quadruplex conformation, resulting in remarkable quenching of the guanine CL intensity of guanine-rich DNA. The CL intensity of this CL system decreased with increasing K(+) concentration, revealing a linear relationship in K(+) concentration range from 3 × 10(-5) to 1 × 10(-3) M. A complete detection process can be accomplished in about 5 min. Other common cations (such as Na(+), NH4 (+), Mg(2+), Ca(2+), Zn(2+), and Pb(2+)) did not notably interfere with K(+) detection. The mechanism of this strategy is also discussed. The sensing strategy is low cost and simple without the requirement of complex labeling of probe DNA. The scheme is applicable to the detection of other guanine-rich aptamer-binding chemicals or biomolecules.
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