An examination of the selective targeting of quantum dots via the folate receptor

Semiconductor nanocrystals known as quantum dots (QDs) are emerging as an important new class of fluorescent probes in cell biology due to their many advantageous optical properties. Various methods have devised that allow for the selective targeting of QDs to biological cells. Conjugation of QDs to small biomolecules has proven effective, allowing for their uptake into mammalian cell lines. We explored the use of folate conjugated QDs in the selective targeting of model cell lines known to have high expression of the folate receptor (FR). Characterization of QDs and QD conjugates is examined using techniques such as spectroscopy, transmission electron microscopy, dynamic light scattering, and zeta potential measurements. Uptake of QDs into cells is examined using both epifluorescence microscopy with multispectral imaging as well as confocal microscopy. Finally the implications for the selective targeting of QDs into cells via the FR are discussed, given their potential use in photodynamic therapy.À cause de leurs multiples et uniques propriétés optiques, les nanocristaux semi-conducteurs ou points quantiques (PQs) émergent comme une nouvelle classe de sondes fluorescentes en biologie moléculaire. Diverses méthodes ont été conçues pour optimiser l'interaction des PQs avec les cellules biologiques. La conjugaison de PQs à de petites biomolécules est efficacement maîtrisée, permettant ainsi leur entrée dans une variété de cellules. Nous avons exploré l'utilisation des conjugués foliques de PQs dans l'interaction sélective avec une variété de cellules modèles connues pour avoir des niveaux élevés de récepteurs foliques (FR). La caractérisation des PQs ou des conjugués de PQs est examinée en utilisant une variété des techniques. La prise de PQs par des cellules est examinée aussi bien avec la microscopie d'épifluorescence, qu'avec la microscopie confocale. Enfin, vu leur potentiel d'application en thérapie photo dynamique, les implications d'une meilleure interaction entre les PQ et les cellules ayant des FR sont discutées

Telomere-to-telomere genome assembly of Phaeodactylum tricornutum

Phaeodactylum tricornutum is a marine diatom with a growing genetic toolbox available and is being used in many synthetic biology applications. While most of the genome has been assembled, the currently available genome assembly is not a completed telomere-to-telomere assembly. Here, we used Oxford Nanopore long reads to build a telomere-to-telomere genome for Phaeodactylum tricornutum. We developed a graph-based approach to extract all unique telomeres, and used this information to manually correct assembly errors. In total, we found 25 nuclear chromosomes that comprise all previously assembled fragments, in addition to the chloroplast and mitochondrial genomes. We found that chromosome 19 has filtered long-read coverage and a quality estimate that suggests significantly less haplotype sequence variation than the other chromosomes. This work improves upon the previous genome assembly and provides new opportunities for genetic engineering of this species, including creating designer synthetic chromosomes