RESUMO
We present avidity sequencing, a sequencing chemistry that separately optimizes the processes of stepping along a DNA template and that of identifying each nucleotide within the template. Nucleotide identification uses multivalent nucleotide ligands on dye-labeled cores to form polymerase-polymer-nucleotide complexes bound to clonal copies of DNA targets. These polymer-nucleotide substrates, termed avidites, decrease the required concentration of reporting nucleotides from micromolar to nanomolar and yield negligible dissociation rates. Avidity sequencing achieves high accuracy, with 96.2% and 85.4% of base calls having an average of one error per 1,000 and 10,000 base pairs, respectively. We show that the average error rate of avidity sequencing remained stable following a long homopolymer.
Assuntos
DNA , Nucleotídeos , Nucleotídeos/genética , Nucleotídeos/química , DNA/genética , DNA/química , Replicação do DNA , Pareamento de Bases , PolímerosRESUMO
Drug delivery to the eye remains a key challenge, due to limitations inherent to prevailing delivery techniques. For example, while topical delivery offers simplicity and safety, its efficacy is often limited by poor bioavailability, due to natural transport barriers and clearance mechanisms. Similarly, while intravitreal injections performed across the ocular tunic provide means for circumventing such limitations, non-negligible potential for retinal detachment and other complications adversely affects safety. Herein, we discuss our initial efforts to address these limitations through development of titanium-based microneedles (MNs) which seek to provide a safer, simpler, and more efficacious means of ocular drug delivery. Devices with in-plane geometry and through-thickness fenestrations that serve as drug reservoirs for passive delivery via diffusive transport from fast-dissolving coatings are demonstrated. Details regarding device design, fabrication, and mechanical testing are presented, as are results from preliminary coating characterization and insertion testing in ex vivo rabbit cornea.
